ORCID Profile
0000-0001-8611-7258
Current Organisation
University of Sydney
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Publisher: American Roentgen Ray Society
Date: 10-2011
DOI: 10.2214/AJR.10.5238
Publisher: International Union of Crystallography (IUCr)
Date: 13-08-2018
DOI: 10.1107/S1600577518010172
Abstract: The aim of this study was to highlight the advantages that propagation-based phase-contrast computed tomography (PB-CT) with synchrotron radiation can provide in breast cancer diagnostics. For the first time, a fresh and intact mastectomy s le from a 60 year old patient was scanned on the IMBL beamline at the Australian Synchrotron in PB-CT mode and reconstructed. The clinical picture was described and characterized by an experienced breast radiologist, who underlined the advantages of providing diagnosis on a PB-CT volume rather than conventional two-dimensional modalities. Subsequently, the image quality was assessed by 11 breast radiologists and medical imaging experts using a radiological scoring system. The results indicate that, with the radiation dose delivered to the s le being equal, the accuracy of a diagnosis made on PB-CT images is significantly higher than one using conventional techniques.
Publisher: SPIE
Date: 11-03-2014
DOI: 10.1117/12.2044436
Publisher: SPIE
Date: 23-02-2012
DOI: 10.1117/12.911638
Publisher: SPIE
Date: 11-03-2014
DOI: 10.1117/12.2043345
Publisher: SPIE
Date: 20-02-2012
DOI: 10.1117/12.911639
Publisher: Elsevier BV
Date: 11-2014
DOI: 10.1016/J.ACRA.2014.06.013
Abstract: To determine the impact of mammographic breast density on the visual search process of radiologists when reading digital mammograms. Institutional review board approval was obtained. A set of 149 craniocaudal digital mammograms were read by seven radiologists, and observer search patterns were recorded. Total time examining each case, time to first hit the lesion, dwell time, and number of hits per area were calculated. The nonparametric Mann-Whitney U test was used for statistical evaluation. In both low- and high-mammographic density cases, significant increases were observed in the time to first hit lesions when they were located outside, compared to overlying fibroglandular dense tissue (P = .001). Significantly longer dwell time (P = .003) and greater number of fixations (P = .0003) were observed when the lesions were situated within--rather than outside--the dense fibroglandular tissue. Increased mammographic breast density changes radiologists' visual search patterns. Dense areas of the parenchyma attracted greater visual attention in both high- and low-mammographic density cases, resulting in faster detection of lesions overlying the fibroglandular dense tissue, along with longer dwell times and greater number of fixations, as compared to lesions located outside the dense fibroglandular regions.
Publisher: SPIE
Date: 06-07-2018
DOI: 10.1117/12.2318320
Publisher: SPIE
Date: 06-07-2018
DOI: 10.1117/12.2318321
Publisher: Elsevier BV
Date: 06-2019
Publisher: SPIE
Date: 28-03-2013
DOI: 10.1117/12.2008103
Publisher: Elsevier BV
Date: 10-2020
Publisher: Elsevier BV
Date: 05-2010
Publisher: British Institute of Radiology
Date: 07-2013
DOI: 10.1259/BJR.20120028
Publisher: Springer International Publishing
Date: 2014
Publisher: Elsevier BV
Date: 04-2014
DOI: 10.1016/J.ACRA.2013.12.002
Abstract: To measure the effect of explicit prevalence expectation on the performance of experienced radiologists during image interpretation of pulmonary lesions on chest radiographs. Each of 22 experienced radiologists was allocated to one of three groups to interpret a set of 30 (15 abnormal) posteroanterior chest images on two occasions to decide if pulmonary lesions were present. Before each viewing, the radiologists were told that the images contained a specific number of abnormal images: group 1, 9 versus 15 group 2, 22 versus 15 and group 3, not told versus 15, respectively. Eye position metrics and receiver operating characteristics confidence ratings were compared for normal and abnormal images. An analysis of false-positive and false-negative decisions was also performed. For normal images, at higher prevalence expectation, significant increases were noted for duration of image scrutiny (group 1: P = .0004 group 2: P = .007 and group 3: P = .003) and number of fixations per image (group 1: P = .0006 group 2: P = .0004 and group 3: P = .0001). Also for normal images, group 1 demonstrated a significant increase (P = .038) in average confidence ratings when prevalence expectation increased. For abnormal images, at higher prevalence expectation, significant increases were noted for duration of image scrutiny in group 1 (P = .005) and number of fixations per image in group 1 (P = .01) and group 2 (P = .003). Confidence ratings and visual search of the expert radiologists appear to be affected by changing prevalence expectations. The impact of prevalence expectation appears to be more apparent for normal images.
Publisher: Elsevier BV
Date: 02-2012
Publisher: Radiological Society of North America (RSNA)
Date: 10-2013
Abstract: To explore relationships between reader performance and reader characteristics in mammography for specific radiologist groupings on the basis of annual number of readings. The institutional review board approved the study and waived the need for patient consent to use all images. Readers gave informed consent. One hundred sixteen radiologists independently reviewed 60 mammographic cases: 20 cases with cancer and 40 cases with normal findings. Readers located any visualized cancer, and levels of confidence were scored from 1 to 5. A jackknifing free response operating characteristic (JAFROC) method was used, and figures of merit along with sensitivity and specificity were correlated with reader characteristics by using Spearman techniques and standard multiple regressions. Reader performance was positively correlated with number of years since qualification as a radiologist (P ≤ .01), number of years reading mammograms (P ≤ .03), and number of readings per year (P ≤ .0001). The number of years since qualification as a radiologist (P ≤ .004) and number of years of reading mammograms (P ≤ .002) were negatively related to JAFROC values for radiologists with annual volumes of less than 1000 mammographic readings. For in iduals with more than 5000 mammographic readings per year, JAFROC values were positively related to the number of years that the reader was qualified as a radiologist (P ≤ .01), number of years of reading mammograms (P ≤ .002), and number of hours per week of reading mammograms (P ≤ .003). Number of mammographic readings per year was positively related with JAFROC scores for readers with an annual volume between 1000 and 5000 readings (P ≤ .03). Differences in JAFROC scores appear to be more related to specificity than location sensitivity, with the former demonstrating significant relationships with four of the five characteristics analyzed, whereas no relationships were shown for the latter. Radiologists' determinants of performance are associated with annual reading volumes. Ability to recognize normal images is a discriminating factor in in iduals with a high volume of mammographic readings.
Publisher: Springer International Publishing
Date: 2014
Publisher: SPIE
Date: 11-03-2014
DOI: 10.1117/12.2043211
Publisher: Elsevier BV
Date: 11-2010
Publisher: Elsevier BV
Date: 09-2014
Publisher: Wiley
Date: 06-2009
DOI: 10.1118/1.3182497
Publisher: Elsevier BV
Date: 08-2016
Publisher: SPIE
Date: 28-03-2013
DOI: 10.1117/12.2006821
Publisher: SPIE
Date: 17-03-2015
DOI: 10.1117/12.2081749
Publisher: Elsevier BV
Date: 11-2014
DOI: 10.1016/J.ACRA.2014.06.004
Abstract: To investigate the impact of breast density on the performance of radiologists when mammograms are digitally acquired and displayed. A total of 150 craniocaudal digital mammograms including 75 cases with cancer were examined by 14 radiologists ided into two groups: those who read more (six) and less (eight) than 2000 mammograms per year. Cases were classified as low or high mammographic density. For both types of cases, detection of cancers within and outside the dense fibroglandular tissue was investigated. The performance of radiologist was measured using jack-knife free-response receiver operating characteristic (JAFROC) figure of merit (FOM). Radiologists with over 2000 annual reads had significantly higher JAFROC FOM (P = .03) for high (0.76) mammographic density compared to low (0.70) mammographic density cases. When lesions overlaid the fibroglandular tissue, cases with high mammographic density compared to low mammographic density displayed increased location sensitivity for all radiologists (P = .03) and for those radiologists reading more than 2000 mammograms annually (P = .04), whereas JAFROC FOMs increased for all radiologists (P = .05). No significant changes were observed when the lesion was outside the fibroglandular region. Increased mammographic density improves the performance of experienced radiologists when using digital mammograms. This finding, which does not align with those previously reported for film screen systems, may be because of windowing/leveling opportunities available with digital images.
Publisher: Elsevier BV
Date: 04-2008
DOI: 10.1016/J.ACRA.2007.11.005
Abstract: Radiologic image details are best discriminated at luminance levels to which the eye is adapted. Recommendations that ambient light conditions are matched to overall monitor luminance to encourage appropriate adaptation are based on an assumption that clinically significant regions within the image match average monitor luminance. The current work examines this assumption. Three image types were considered: posteroanterior (PA) chest PA wrist and computed tomography (CT) head. Luminance at clinically significant regions was measured at hilar region and peripheral lung (chest), distal radius (wrist), and supraventricular white matter (head). Average monitor luminances were calculated from measurements at 16 regions of the display face plate. Three ambient light levels-30, 100 and 400 lux-were employed. Thirty s les of each image type were used. Statistically significant differences were noted between average monitor luminances and clinically important regions of interest of up to a factor of 3.8, 2, and 6.3 for chest, wrist, and CT head images respectively (P < .0001). Values for the hilum of the chest and distal radius were higher than average monitor levels, whereas the reverse was observed for the peripheral lung and CT brain. Increasing ambient light had no impact on results. Clinically important radiologic information for common radiologic examinations is not being presented to observers in a way that facilitates optimized adaptation. This may have a significant impact on the ability of the observer to identify details with low contrast discriminability. The importance of image-processing algorithms focussing on clinically significant abnormalities rather than anatomic regions is highlighted.
Publisher: MedCrave Group, LLC
Date: 05-03-2020
Publisher: Bentham Science Publishers Ltd.
Date: 08-2010
Publisher: SPIE
Date: 26-02-2009
DOI: 10.1117/12.813510
Publisher: SPIE
Date: 15-04-2005
DOI: 10.1117/12.593954
Publisher: SPIE
Date: 26-02-2009
DOI: 10.1117/12.809132
Publisher: Hindawi Limited
Date: 27-12-2013
DOI: 10.1111/ECC.12169
Abstract: This study aims to explore Australian radiologists' experiences of participating in breast cancer multi-disciplinary team (MDT) meetings to identify enablers and barriers to participation as well their perception of confidence and patient care. Qualitative methods incorporating observation and interviews were used. Twenty-one breast cancer MDT meetings were observed across Sydney to study the dynamics of the meetings, the level of participation by radiologists and their most important interactions. Qualitative semi-structured interviews were conducted with 10 radiologists participating in these meetings regarding participation, educational opportunities and improvements to work practices. Radiologists' participation in breast cancer MDT meetings is influenced by the type of meeting they attend with higher levels of participation and a more dominant 'valued' role being evident in pre-interventional meetings. The key themes to emerge from the data include the importance of 'sharing experiences', the 'radiologist-pathologist relationship' and the value of 'continuing participation'. Radiologists believed their confidence in their clinical decision making increased when there was immediate feedback from pathologists. This study highlights the benefits of radiologists regularly participating in breast cancer MDT meetings in terms of continuing professional education resulting from collegial experiential learning. Radiologists' perceived patient care and workplace isolation were improved by sharing experiences with other cancer care colleagues.
Publisher: Public Library of Science (PLoS)
Date: 26-02-2016
Publisher: SPIE-Intl Soc Optical Eng
Date: 24-01-2017
Publisher: SPIE
Date: 28-03-2013
DOI: 10.1117/12.2007360
Publisher: SPIE
Date: 04-03-2019
DOI: 10.1117/12.2513106
Publisher: Elsevier BV
Date: 12-2011
DOI: 10.1016/J.JMIR.2011.05.003
Abstract: Increased speeds of computed tomography (CT) acquisition and concomitant increased intravenous (IV) bolus injection rates have placed patients at greater risk of contrast extravasation. To assess the efficacy of the MEDRAD XDS extravasation detector by recording the incidence of contrast extravasation in high-risk patients during CT angiography. We prospectively collected data on 25 adults ages 45 to 85 years (mean=65 years), all of whom were considered to be at high risk of having a contrast extravasation. All patients underwent CT angiography with power-injected IV contrast injection introduced via an antecubital venous line. Details recorded included patient age and weight, contrast volume, flow rate, maximum injector pressure, image quality, and extravasation incidence and volume. The size of the most commonly used cannula was 20 gauge and the flow rates ranged from 4.0 to 6 mL/second. The XDS device alerted the clinicians to five episodes of extravasation. These were identified at an early stage of the injection with no more than 8 mL of contrast material having been introduced. The utility of this device has been demonstrated and its employment should reduce extravasated contrast volumes with minimum discomfort to high-risk patients.
Publisher: Wiley
Date: 04-2015
Abstract: This study aims to evaluate the effectiveness of zooming in improving screen-reader performance in reporting digital mammograms. Two experiments were conducted. In the first experiment, 5 readers were asked to report 59 two-view bilateral mammograms retrospectively with zooming function turned off. The second session was similar to the first one except that zooming was enabled. The task of readers was to assess if the mammograms were normal or abnormal and rate the confidence levels for each of the lesion they detected. The reader performances were evaluated via case sensitivity, lesion sensitivity, specificity, receiver operating characteristics (ROC) area under the curve (AUC) and jackknife free-response receiver operating characteristics (JAFROC) figure of merit (FOM). There was no significant improvement in overall reader performance in detecting abnormalities in zooming condition compared with no zooming in terms of case sensitivity (96% and 87%, P = 0.285) or lesion sensitivity (88% and 81%, P = 0.224). However, differences in ROC AUC and JAFROC FOM (P ≤ 0.05) were found in two readers when they performed the test set with zooming function. The results suggested that the use of the zooming function did improve the performance of some readers in detecting abnormal cases.
Publisher: SPIE
Date: 11-03-2014
DOI: 10.1117/12.2043321
Publisher: Korean Cancer Association
Date: 15-10-2017
DOI: 10.4143/CRT.2016.488
Publisher: American Roentgen Ray Society
Date: 02-2007
DOI: 10.2214/AJR.05.2048
Publisher: Oxford University Press (OUP)
Date: 17-01-2018
DOI: 10.1093/RPD/NCX306
Abstract: Cardiac computed tomography angiography (CCTA) is a commonly used diagnostic imaging tool for cardiovascular disease. Despite constant improvements to imaging technologies, the radiation dose to patients remains a concern when using this procedure. Diagnostic reference levels (DRLs) are used as a trigger to identify and alert in idual facilities that are using high doses during CT. This study aims to assess patient radiation dose and establish new national DRLs (NDRL) associated with CCTA in Saudi clinical practices. A structured booklet survey was designed for recording patient and scanning protocols during CCTA procedures. The data were collected retrospectively from the participating centres. NDRLs for CCTA were defined as the 75th and 25th of volumetric CT dose index (CTDIvol) and dose length product (DLP). Specific DRLs based on two main ECG-gating modes were also proposed. Data sets related to 197 CCTAs with a mean weight of 77 kg were analysed in detail. The DRL values for CTDIvol and DLP for prospective gating mode and retrospective gating mode were 29 and 62 mGy and 393 and 1057 mGy cm, respectively. NDRLs for CCTA in Saudi Arabia are comparable or slightly lower than European DRLs due to the current use of dose-saving technology. There are major variations in patient doses during CCTA due to differences in CT scanners, scanning modes and departmental CCTA protocols.
Publisher: Hindawi Limited
Date: 31-01-2019
DOI: 10.1111/TBJ.13209
Abstract: A radiation dose survey has been undertaken involving 256 patients to investigate the dosimetric impact of breast tomosynthesis screening by employing different breast densities estimated by the Dance model, 50-50 breast model, and patient-specific density software: Volpara. Mean glandular dose (MGD) based on the Dance model provided the most realistic dose estimate with an average difference of -3.3 ± 4.8% from the patient-specific estimation. Average differences of -8.2 ± 6.5% and -7.3 ± 4.7% were observed for the 50-50 breast model and console MGD, respectively. We conclude that the Dance model should be used for dose calculations in radiation dose surveys and establishing diagnostic reference levels (DRL).
Publisher: Wiley
Date: 15-02-2019
Abstract: The aim of this work is to report diagnostic reference levels (DRLs) for hybrid positron emission tomography and x-ray computed tomography (PET/CT) exams in Australia (AU) for Queensland (QLD) and Western Australia (WA) (AU QLD/WA) and New Zealand (NZ). Two-structured booklets were designed to collect dose information, patient demographics, equipment details and acquisition protocols for fluoride-18 fluorodeoxyglucose ( The findings of this study show that the current DRL for The current DRLs were proposed for AU QLD/WA and NZ for
Publisher: Wiley
Date: 02-2019
Abstract: Differences in radiologists' experience can potentially introduce interobserver variability in reading mammograms. This work investigated the effect of radiologists' experience on agreement on mammographic final classification. This was a cross-sectional study. Seventeen radiologists were asked to provide their final impression on 60 mammogram cases. Experience parameters included breast subspecialty, years reading mammograms, cases read per year and career caseload. Career caseload was calculated by multiplying years reading mammograms by the average number of cases read per year. The interobserver agreement was calculated using Cohen kappa (κ). The difference in κ between radiologists' groups was compared using the independent-s le t-test and analysis of variance. The average interobserver agreement was 0.25 (fair). A small difference was found in favour of breast radiologists against general radiologists (κ = 0.21 and 0.29, respectively, P = 0.019). Years reading mammograms and cases read per year did not seem to significantly affect the interobserver agreement (P = 0.056 and 0.273 respectively). Radiologist who had career caseload of at least 2500 cases showed significantly higher consistency than those who read less. κ for radiologists who had career caseload of 2500-4000 cases and >4000 cases was 0.33 and 0.28, respectively, whereas for <2500 κ was 0.17 (P = 0.001). A fair level of interobserver agreement on the final classification of a mammogram was demonstrated. Career caseload was the most important experience parameter to associate with the interobserver agreement. Training strategies aiming to increase radiologists' career caseload may be beneficial.
Publisher: Elsevier BV
Date: 09-2011
DOI: 10.1016/J.JMIR.2011.05.002
Abstract: Contrast medium (CM) administration for multidetector computed tomography angiography (CTA) requires using a power injector. Power injectors deliver viscous CM at different flow rates up to a maximum pressure of 300 lb per square inch (psi), provide features that benefit patient safety, improve arterial and parenchymal opacification, and allow flexible and complex injection protocols to be administered. The use of power injectors not only includes contrast but also saline, which is primarily responsible for reducing the overall volume of contrast administration while maintaining peak vessel opacification over a longer duration during the CTA acquisition. CTA faces multiple challenges with advanced scanner hardware. There is an increased need to inject small volumes of CM at fast injection rates over a short duration. This technical overview is to increase the understanding of parameters that influence optimal contrast enhancement and bolus geometry, and to enable the user to modify and optimize scanner and contrast protocols.
Publisher: Elsevier BV
Date: 04-2017
DOI: 10.1016/J.ACRA.2016.11.020
Abstract: Visual search is an inhomogeneous yet efficient s ling process accomplished by the saccades and the central (foveal) vision. Areas that attract the central vision have been studied for errors in interpretation of medical imaging. In this study, we extend existing visual search studies to understand what characterizes areas that receive direct visual attention and elicit a mark by the radiologist (True and False Positive decisions) from those that elicit a mark but were captured by the peripheral vision. We also investigate if there are any differences between these areas and those that are never fixated by radiologists. Eight radiologists participated in this fully crossed multi-reader multi-case visual search study of digital mammography (DM) involving 120 two-view cases (59 cancers). From these DM images, 3 types of areas, namely Fixated Clusters (FC), Marked Peripherally Fixated Clusters (MPFC) and Never Fixated Clusters (NFC), were extracted and analysed using statistical information theory (in the form of third and fourth-order cumulants and polyspectrum [specifically bispectrum and trispectrum]) in addition to traditional second-order statistics (in the form of power spectrum) and other nonspectral features to characterize these types of areas. Our results suggest that energy profiles of FC, MPFC, and NFC areas are distinct. We found evidence that energy profiles and dwell time of these areas influence radiologists' decisions (and confidence in such decisions). We also noted that foveated areas are selected on the basis of being most informative. We show that properties of these areas influence radiologists' decisions and their confidence in the decisions made.
Publisher: SAGE Publications
Date: 29-04-2016
Abstract: Background. Lower breast density (BD) is associated with lower risk of breast cancer and may serve as a biomarker for the efficacy of chemopreventive strategies. This review explores parameters that are thought to be associated with lower BD. We conducted a systematic review of articles published to date using the PRISMA strategy. Articles that assessed change in BD with estrogen-receptor modulators (tamoxifene [TAM], raloxifene [RLX], and tibolone) and aromatase inhibitors (AIs), as well as cross-sectional and longitudinal studies (LSs) that assessed association between BD and physical activity (PA) or diet were reviewed. Results. Ten studies assessed change in BD with TAM all reported TAM-mediated BD decreases. Change in BD with RLX was assessed by 11 studies 3 reported a reduction in BD. Effect of tibolone was assessed by 5 RCTs only 1 reported change in BD. AI-mediated BD reduction was reported by 3 out of 10 studies. The association between PA and BD was assessed by 21 studies 4 reported an inverse association. The relationship between diet and BD was assessed in 34 studies. All studies on calcium and vitamin D as well as vegetable intake reported an inverse association with BD in premenopausal women. Two RCTs demonstrated BD reduction with a low-fat, high-carbohydrate intervention. Conclusion. TAM induces BD reduction however, the effect of RLX, tibolone, and AIs on BD is unclear. Although data on association between diet and BD in adulthood are contradictory, intake of vegetables, vitamin D, and calcium appear to be associated with lower BD in premenopausal women.
Publisher: Elsevier BV
Date: 02-2020
DOI: 10.1016/J.CRAD.2019.10.006
Abstract: Accurate interpretation of radiological images involves a complex visual search that relies on several cognitive processes, including selective attention, working memory, and decision-making. Patient outcomes often depend on the accuracy of image interpretations, and yet research has revealed that conclusions vary significantly from one radiologist to another. A myriad of factors has been shown to contribute to the likelihood of interpretative errors and discrepancies, including the radiologist's level of experience and fatigue, and these factors are well reported elsewhere however, a potentially important factor that has been given little previous consideration is how radiologists' interpretations might be impacted by the time of day at which the reading takes place, a factor that other disciplines have shown to be a determinant of competency. The available literature shows that while the time of day is known to significantly impact some cognitive functions that likely relate to reading competence, including selective visual attention and visual working memory, little is known about the impact of the time of day on radiology interpretation performance. This review explores the evidence regarding the relationship between time of day and performance, with a particular emphasis on radiological activities.
Publisher: SPIE
Date: 04-03-2010
DOI: 10.1117/12.845226
Publisher: SPIE
Date: 07-03-2018
DOI: 10.1117/12.2293511
Publisher: SPIE
Date: 03-03-2011
DOI: 10.1117/12.878740
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.CRAD.2015.10.009
Abstract: To compare readers' performance in detecting architectural distortion (AD) compared with other breast cancer types using digital mammography. Forty-one experienced breast screen readers (20 US and 21 Australian) were asked to read a single test set of 30 digitally acquired mammographic cases. Twenty cases had abnormal findings (10 with AD, 10 non-AD) and 10 cases were normal. Each reader was asked to locate and rate any abnormalities. Lesion and case-based performance was assessed. For each collection of readers (US Australian combined), jackknife free-response receiver operating characteristic (JAFROC), figure of merit (FOM), and inferred receiver operating characteristic (ROC), area under curve (Az) were calculated using JAFROC v.4.1 software. Readers' sensitivity, location sensitivity, JAFROC, FOM, ROC, Az scores were compared between cases groups using Wilcoxon's signed ranked test statistics. For lesion-based analysis, significantly lower location sensitivity (p=0.001) was shown on AD cases compared with non-AD cases for all reader collections. The case-based analysis demonstrated significantly lower ROC Az values (p=0.02) for the first collection of readers, and lower sensitivity for the second collection of readers (p=0.04) and all-readers collection (p=0.008), for AD compared with non-AD cases. The current work demonstrates that AD remains a challenging task for readers, even in the digital era.
Publisher: SPIE
Date: 24-03-2016
DOI: 10.1117/12.2217654
Publisher: SPIE
Date: 23-02-2012
DOI: 10.1117/12.911610
Publisher: Radiological Society of North America (RSNA)
Date: 02-2017
DOI: 10.1148/RADIOL.2017170306
Abstract: Purpose To compare three mammographic density measures defined by different pixel intensity thresholds as predictors of breast cancer risk for two different digital mammographic systems. Materials and Methods The Korean Breast Cancer Study included 398 women with invasive breast cancer and 737 control participants matched for age at mammography (±1 year), examination date, mammographic system, and menopausal status. Mammographic density was measured by using the automated Laboratory for In idualized Breast Radiodensity Assessment (LIBRA) software and the semiautomated Cumulus software at the conventional threshold (Cumulus) and at increasingly higher thresholds (Altocumulus and Cirrocumulus, respectively). Measures were Box-Cox-transformed and adjusted for age, body mass index, and menopausal status. Conditional logistic regression was used to estimate risk associations. For calculation of measures of predictive value, the change in odds per standard deviation (OPERA) and the area under the receiver operating characteristic curve (AUC) were used. Results For dense area, with use of the direct conversion system the OPERAs were 1.72 (95% confidence interval [CI]: 1.38, 2.15) for LIBRA, 1.58 (95% CI: 1.27, 1.97) for Cumulus, 2.04 (95% CI: 1.60, 2.59) for Altocumulus, and 3.48 (95% CI: 2.45, 4.47) for Cirrocumulus (P < .001). The corresponding AUCs were 0.70, 0.69, 0.76, and 0.89, respectively. With use of the indirect conversion system, the corresponding OPERAs were 1.50 (95% CI: 1.28, 1.76), 1.36 (95% CI: 1.16, 1.59), 1.40 (95% CI: 1.19, 1.64), and 1.47 (95% CI: 1.25, 1.73) (P < .001) and the AUCs were 0.64, 0.60, 0.61, and 0.63, respectively. Conclusion It is possible that mammographic density defined by higher pixel thresholds could capture more risk-predicting information with use of a direct conversion mammographic system the mammographically bright, rather than white, regions are etiologically important.
Publisher: Springer Science and Business Media LLC
Date: 06-03-2014
DOI: 10.1007/S00062-014-0295-5
Abstract: The purpose of this study was to investigate the diagnostic efficacy of a range of conventional magnetic resonance imaging (MRI) pulse sequences in the identification of internuclear ophthalmoplegia (INO) caused by medial longitudinal fasciculus (MLF) lesions in multiple sclerosis patients using a receiver-operating characteristic (ROC) methodology. A total of 15 clinically confirmed INO and 15 control subjects underwent conventional MRI at 1.5 T consisting of T2-weighted, proton density (PD)-weighted, and fluid-attenuated inversion recovery (FLAIR) sequences, following full institutional approval. A free-response, multiple-reader multiple-case design ROC study was used to evaluate the diagnostic efficacy of each sequence. All imaging sequences were evaluated by 10 board-certified neuroradiologists. Area under the curve (AUC), sensitivity, and specificity were analysed statistically for all three pulse sequences using repeated-measures analyses of variance and post-test analysis using Bonferroni's multiple comparison test of differences. No significant AUC differences were found between the three sequences (p = 0.0697), with T2 recording the highest AUC (0.8346). Sensitivity differences between PD (0.7927) and FLAIR (0.6329) were significant (p < 0.05). Non-significant differences were also evident between T2 and FLAIR (p = 0.0511). The specificity analysis revealed an overall difference (p = 0.0005), with specific inter-sequence differences shown between T2 and PD (p < 0.05) and PD and FLAIR (p < 0.001) with the PD values being lower than those provided with the other two sequences. T2-weighted axial imaging through the MLF region resulted in the greatest overall diagnostic efficacy when viewing a combination of mean AUC, sensitivity, and specificity, in terms of the identification of INO-causing lesions.
Publisher: SPIE
Date: 16-03-2020
DOI: 10.1117/12.2543503
Publisher: SPIE
Date: 06-07-2018
DOI: 10.1117/12.2316498
Publisher: Elsevier BV
Date: 11-2010
DOI: 10.1016/J.ACRA.2010.06.016
Abstract: To determine the relationship between heightened levels of reader performance and reader practice in terms of number of cases read and previous experience. A test set of mammograms was developed comprising 50 cases. These cases consisted of 15 abnormals (biopsy proven) and 35 normals (confirmed at subsequent rescreen). Sixty-nine breast image readers reviewed these cases independently and their performance was measured by recording their in idual receiver operating characteristic score (area under the curve), sensitivity, and specificity. These measures of performance were then compared to a range of factors relating to the reader such as years of certification and reporting, number of cases read per year, previous experiences, and satisfaction levels. Correlation analyses using Spearman methods were performed along with the Mann-Whitney test to detect differences in performance between specific reader groups. Improved reader performance was found for years certified (P = .004), years of experience (P = .0001), and hours reading per week (P = .003) shown by positive statistical significant relationships with Az values (area under receiver operating characteristic curve). Statistical comparisons of Az values scored for in iduals who read varying number of cases per year showed that those in iduals whose annual mammographic case load was 5000 or more (P = .03) or between 2000 and 4999 (P = .05), had statistically significantly higher scores than those who read less than 1000 cases per year. The results of this study have shown variations in reader performance relating to parameters of reader practice and experience. Levels of variance are shown and potential acceptance levels for diagnostic efficacy are proposed which may inform policy makers, judicial systems and public debate.
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.JMIR.2008.11.002
Abstract: Children are more vulnerable to the harmful effects of radiation than adults therefore, every effort should be made to keep radiation doses as low as reasonably achievable. One effective dose-reducing tool for pediatrics is additional filtration. This anthropomorphic phantom-based study explores use of additional filters for the radiographic anteroposterior pelvis examination. Image quality, entrance surface, and effective doses were monitored with the existing inherent level of filtration for 0-, 5-, and 15-year-old pediatric phantoms. A range of filter types and thicknesses were added, including aluminium, copper, and compound (aluminium and copper), and changes were noted. Compared with the current level of filtration, results showed a decrease in entrance surface dose by up to 62.9%, 56.4%, and 55.0%, and effective dose by up to 46.4%, 36.1%, and 28.7% for the 0-, 5-, and 15-year-olds, respectively. No significant degradation in image quality was noted. Despite compound filters offering marginal benefits over copper, 0.3 mm copper filtration is recommended for clinical trials because of reduced physical thickness. Results demonstrated that additional filtration in excess of current recommendations may offer important benefits for children undergoing this radiographic examination.
Publisher: Elsevier BV
Date: 12-2009
DOI: 10.1016/J.ACRA.2009.07.010
Abstract: American College of Radiology guidelines suggest that digital screening mammographic images should be viewed at the full resolution at which they were acquired. This slows interpretation speed. The aim of this study was to examine the effect of various levels of zooming on the detection and conspicuity of microcalcifications. Six radiologists viewed 40 mammographic images five times in different random orders using five different levels of zooming: full resolution (100%) and 30%, 61%, 88%, and 126% of that size. Thirty-three images contained microcalcifications varying in subtlety, all associated with breast cancer. The clusters were circled. Seven images contained no malignant calcifications but also had randomly placed circles. The radiologists graded the presence or absence and visual conspicuity of any calcifications compared to calcifications in a reference image. They also counted the microcalcifications. The radiologists saw the microcalcifications in 94% of the images at 30% size and in either 99% or 100% of the other tested levels of zooming. Conspicuity ratings were worst for the 30% size and fairly similar for the others. Using the 30% size, two radiologists failed to see the microcalcifications on either the craniocaudal or mediolateral oblique view taken from one patient. Interobserver agreement regarding the number of calcifications was lowest for the 30% images and second lowest for the 100% images. Images at 30% size should not be relied on alone for systematic scanning for microcalcifications. The other four levels of magnification all performed well enough to warrant further testing.
Publisher: SPIE
Date: 17-03-2015
DOI: 10.1117/12.2083149
Publisher: British Institute of Radiology
Date: 10-2020
DOI: 10.1259/BJR.20200363
Abstract: This study aims to explore the reading performances of radiologists in detecting cancers on mammograms using Tabar Breast Imaging Reporting and Data System (BIRADS) classification and identify factors related to breast imaging reporting scores. 117 readings of five different mammogram test sets with each set containing 20 cancer and 40 normal cases were performed by Australian radiologists. Each radiologist evaluated the mammograms using the BIRADS lexicon with category 1 - negative, category 2 - benign findings, category 3 - equivocal findings (Recall), category 4 - suspicious findings (Recall), and category 5 - highly suggestive of malignant findings (Recall). Performance metrics (true positive, false positive, true negative, and false negative) were calculated for each radiologist and the distribution of reporting categories was analyzed in reader-based and case-based groups. The association of reader characteristics and case features among categories was examined using Mann-Whitney U and Kruskal-Wallis tests. 38% of cancer-containing mammograms were reported with category 3 which decreased to 32.3% with category 4 and 16.2% with category 5 while 16.6 and 10.3% of cancer cases were marked with categories 1 and 2. Female readers had less false-negative rates when using categories 1 and 2 for cancer cases than male readers (p 0.01). A similar pattern as gender category was also found in Breast Screen readers and readers completed breast reading fellowships compared with non-Breast Screen and non-fellowship readers (p 0.05). Radiologists with low number of cases read per week were more likely to record the cancer cases with category 4 while the ones with high number of cases were with category 3 (p 0.01). Discrete mass and asymmetric density were the two types of abnormalities reported mostly as equivocal findings with category 3 (47–50% p = 0.005) while spiculated mass or stellate lesions were mostly selected as highly suggestive of malignancy with category 5 (26%, p = 0.001). Most radiologists used category 3 when reporting cancer mammograms. Gender, working for BreastScreen, fellowship completion, and number of cases read per week were factors associated with scoring selection. Radiologists reported higher Tabar BIRADS category for specific types of abnormalities on mammograms than others. The study identified factors associated with the decision of radiologists in assigning a BIRADS Tabar score for mammograms with abnormality. These findings will be useful for in idual training programs to improve the confidence of radiologists in recognizing abnormal lesions on screening mammograms.
Publisher: Elsevier BV
Date: 12-2016
DOI: 10.1016/J.BREAST.2016.10.003
Abstract: To assess the agreement between digital breast tomosynthesis (DBT) breast density (BD) assessment made using Quantra™ and fifth edition BI-RADS This board approved study involved BD assessment of 234 women undergoing DBT investigation. BD estimation was performed from the raw DBT images using Quantra™ 3 (v.2.1.1, Hologic, Bedford MA). BI-RADS Inter-reader agreement varied from fair [0.38 (95%CI: 0.30-0.46)] to substantial [0.68 (95%CI: 0.61-0.75)] on a four-category scale and substantial [0.70 (95%CI: 0.61-0.78)] to almost perfect [0.85 (95%CI: 0.78-0.92)] on a two-category scale. Using the majority report, the agreement between BI-RADS Data demonstrate moderate to substantial agreement in BD assessment between fifth edition BI-RADS
Publisher: SPIE
Date: 22-05-2020
DOI: 10.1117/12.2564275
Publisher: SPIE
Date: 22-05-2020
DOI: 10.1117/12.2564276
Publisher: Elsevier BV
Date: 2016
Publisher: SPIE
Date: 24-03-2016
DOI: 10.1117/12.2217886
Publisher: SPIE
Date: 24-03-2016
DOI: 10.1117/12.2217704
Publisher: Elsevier BV
Date: 05-2009
Publisher: SPIE
Date: 03-03-2011
DOI: 10.1117/12.877958
Publisher: Elsevier BV
Date: 2017
Publisher: Wiley
Date: 10-09-2018
Abstract: This narrative literature review aims to identify the various factors that have significant impact on radiologists' visual search patterns. Identifying the factors that influences readers' visual search behaviour helps to understand their perception and interpretation of medical images, which in turn could lead to the development and implementation of effective strategies that could aid in improving the ability to detect abnormalities. Databases including PubMed, MedLine, Web of Science and ScienceDirect were searched using terms 'visual search', 'eye-tracking', 'radiology OR radiography', 'mammogram OR mammography' published since the early 1960s until June 30, 2016. Some of the factors that have been identified to significantly influence radiologists' visual search patterns were (i) readers' expertise, (ii) Satisfaction of Search, (iii) readers' visual fatigue, (iv) readers' confidence in reporting abnormalities, (v) training received and (vi) readers' prior knowledge. Readers' level of expertise was the factor that has been identified to have the most significant impact on their visual search pattern. Eye-tracking studies have shown the differences in visual search patterns of readers with different levels of experience and not so surprisingly, more experienced readers have shown effective visual search strategies. Readers' expertise has also been found to have significant impact in their confidence in reporting abnormalities and their ability to discriminate lesions from background structures in medical images.
Publisher: The Optical Society
Date: 03-10-2014
Publisher: SPIE
Date: 02-03-2006
DOI: 10.1117/12.641623
Publisher: Elsevier BV
Date: 2021
Publisher: Wiley
Date: 06-2008
DOI: 10.1118/1.2962720
Publisher: Wiley
Date: 23-06-2020
DOI: 10.1002/JMRS.414
Publisher: SPIE
Date: 04-03-2010
DOI: 10.1117/12.844193
Publisher: SPIE
Date: 22-05-2020
DOI: 10.1117/12.2564280
Publisher: British Institute of Radiology
Date: 03-2013
DOI: 10.1259/BJR.20120500
Publisher: Elsevier BV
Date: 05-2008
Publisher: SPIE
Date: 11-03-2014
DOI: 10.1117/12.2044362
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.ACRA.2018.03.003
Abstract: Image reporting is a vital component of patient management depending on in idual radiologists' performance. Our objective was to explore mammographic diagnostic efficacy in a country where breast cancer screening does not exist. Two mammographic test sets were used: a typical screening (TS) and high-difficulty (HD) test set. Nonscreening (NS) radiologists (n = 11) read both test sets, while 52 and 49 screening radiologists read the TS and HD test sets, respectively. The screening radiologists were classified into two groups: a less experienced (LE) group with ≤5 years' experience and a more experienced (ME) group with ≥5 years' experience. A Kruskal-Wallis and Tukey-Kramer post hoc test were used to compare reading performance among reader groups, and the Wilcoxon matched pairs tests was used to compare TS and ND test sets for the NS radiologists. Across the three reader groups, there were significant differences in case sensitivity (χ Large variations in mammographic performance exist between radiologists from screening and nonscreening countries.
Publisher: SPIE
Date: 03-03-2011
DOI: 10.1117/12.877964
Publisher: MDPI AG
Date: 20-02-2023
Abstract: Background: This study aims to investigate the diagnostic efficacy of radiologists when reading screening mammograms in the absence of previous images, and with the presence of prior images from the same and different vendors. Methods: 612 radiologists’ readings across 9 test sets, consisting of 540 screening mammograms (361-normal and 179-cancer) with 245 cases having prior images obtained from same vendor as current images, 129 from a different vendor and 166 cases having no prior images, were retrospectively analysed. True positive (sensitivity), true negative (specificity) and area under ROC curve (AUC) values of radiologists were calculated for three groups of cases (without prior images (NP), with prior images from same vendor (SP), and with prior images from different vendor (DP)). Logistic regression was used to estimate the odds ratio (OR) of true positive, true negative and true cancer localization among case groups with different levels of breast density and lesion characteristics. Results: Radiologists obtained 12.8% and 10.3% higher sensitivity in NP and DP than SP (0.803-and-0.785 vs. 0.712 p 0.0001). Specificity in NP and DP cases were 4.8% and 2.0% lower than SP cases (0.749 and 0.771 vs. 0.787). The AUC values for NP and DP were significantly higher than SP cases across different levels of breast density (0.814-and-0.820 vs. 0.782 p 0.0001). The odds ratio (OR) of true positive for NP relative to SP was 1.6 (p 0.0001) and DP relative to SP was 1.5 (p 0.0001). Radiologists were more like to detect architectural distortion in DP than SP cases (OR = 3.2 p 0.0001), whilst the OR for abnormal calcifications was 2.85 (p 0.0001). Conclusions: Cases without previous mammograms or with prior mammograms obtained from different vendors were more likely to benefit radiologists in cancer detection, whilst prior mammograms undertaken from the same vendor were more useful for radiologists in evaluating normal cases.
Publisher: Wiley
Date: 06-10-2016
Abstract: This work aims to explore radiation doses delivered in screening mammography in Australia, with a focus on whether compressed breast thickness should be used as a guide when determining patient derived diagnostic reference levels (DRLs). Anonymized mammograms (52,405) were retrieved from a central database, and DICOM headers were extracted using third party software. Women with breast implants, breast thicknesses outside 20-110 mm and images with incomplete exposure or quality assurance (QA) data were excluded. Exposure and QA information were utilized to calculate the mean glandular dose (MGD) for 45,054 mammograms from 61 units representing four manufacturers using previously well-established methods. The 75th and 95th percentiles were calculated across median image MGDs obtained for all included data and according to specific compressed breast thickness ranges. The overall median image MGD, minimum, maximum were: 1.39, 0.19 and 10.00 mGy, respectively, the 75th and 95th percentiles across all units' median image MGD for 60 ± 5 mm compressed breast thickness were 2.06 and 2.69 mGy respectively. Median MGDs, minimum, maximum, 75th and 95th percentiles were presented for nine compressed breast thickness ranges, DRLs for NSW are suggested for the compressed breast thickness range of 60 ± 5 mm for the whole study and three detector technologies CR, DR, and photon counting to be 2.06, 2.22, 2.04 and 0.79 mGy respectively. MGD is dependent upon compressed breast thickness and it is recommended that DRL values should be specific to compressed breast thickness and image detector technology.
Publisher: British Institute of Radiology
Date: 2013
DOI: 10.1259/BJR/27961545
Publisher: Wiley
Date: 04-2015
Abstract: Test sets have been increasingly utilised to augment clinical audit in breast screening programmes however, their relationship has never been satisfactorily understood. This study examined the relationship between mammographic test set performance and clinical audit data. Clinical audit data over a 2-year period was generated for each of 20 radiologists. Sixty mammographic examinations, consisting of 40 normal and 20 cancer cases, formed the test set. Readers located any identifiable cancer, and levels of confidence were scored from 2 to 5, where a score of 3 and above is considered a recall rating. Jackknifing free response operating characteristic (JAFROC) figure-of-merit (FOM), location sensitivity and specificity were calculated for in idual readers and then compared with clinical audit values using Spearman's rho. JAFROC FOM showed significant correlations to: recall rate at a first round of screening (r = 0.51 P = 0.02) rate of small invasive cancers per 10 000 reads (r = 0.5 P = 0.02) percentage of all cancers read that were not recalled (r = -0.51 P = 0.02) and sensitivity (r = 0.51 P = 0.02). Location sensitivity demonstrated significant correlations with: rate of small invasive cancers per 10 000 reads (r = 0.46 P = 0.04) rate of DCIS (ductal carcinoma in situ) per 10 000 reads (r = 0.44 P = 0.05) detection rate of all invasive cancers and DCIS per 10 000 reads (r = 0.54 P = 0.01) percentage of all cancers read that were not recalled (r = -0.57 P = 0.009) and sensitivity (r = 0.57 P = 0.009). No other significant relationships were noted. Performance indicators from test set demonstrate significant correlations with specific aspects of clinical performance, although caution needs to be exercised when generalising test set specificity to the clinical situation.
Publisher: Radiological Society of North America (RSNA)
Date: 10-2011
Publisher: Springer International Publishing
Date: 2014
Publisher: Hindawi Limited
Date: 29-11-2018
DOI: 10.1111/TBJ.12967
Publisher: Oxford University Press (OUP)
Date: 18-02-2016
DOI: 10.1093/RPD/NCW005
Abstract: This phantom-based study aimed to examine radiation dose from digital breast tomosynthesis (DBT) and digital mammography (DM) and to assess the potential for dose reductions for each modality. Images were acquired at 10-60 mm thicknesses and four dose levels and mean glandular dose was determined using a solid-state dosemeter. Eleven readers assessed image quality and compared simulated lesions with those on a reference image, and the data produced was analysed with the Friedman and Wilcoxon signed-rank tests. For a phantom thickness of 50 mm (typical breast thickness), DBT dose was 13 % higher than DM, but this differential is highly dependent on thickness. Visibility of masses was equal to a reference image (produced at 100 % dose) when dose was reduced by 75 and 50 % for DBT and DM. For microcalcifications, visibility was comparable with the reference image for both modalities at 50 % dose. This study highlighted the potential for reducing dose with DBT.
Publisher: Hindawi Limited
Date: 27-11-2018
DOI: 10.1111/TBJ.12963
Publisher: Oxford University Press (OUP)
Date: 22-02-2016
DOI: 10.1093/RPD/NCW012
Abstract: This study examines radiation dose levels delivered to children from birth to 15 y of age in the investigation of congenital heart disease (CHD) at a major Sydney children's hospital. The aims are to compare values with those derived from similar studies, to provide a template for more consistent dose reporting, to establish local and national diagnostic reference levels and to contribute to the worldwide paediatric dosimetry database. A retrospective review of 1007 paediatric procedural records was undertaken. The cohort consisted of 795 patients over a period from January 2007 to December 2012 who have undergone cardiac catheterisation for the investigation of CHD. The age range included was from the day of birth to 15 y. Archived dose area product (DAP) and fluoroscopy time (FT) readings were retrieved and analysed. The mean, median, 25th and 75th percentile DAP levels were calculated for six specific age groupings. The 75th percentile DAP values for the specific age categories were as follows: 0-30 d-1.9 Gy cm2, 1-12 months-2.9 Gy cm2, 1-3 y-5.3 Gy cm2, 3-5 y-6.2 Gy cm2, 5-10 y-7.5 Gy cm2 and 10-15 y-17.3 Gy cm2. These levels were found to be lower than the values reported in comparable overseas studies. In idual year-specific levels were determined, and it is proposed that these are more useful than the common grouping method. The age-specific 75th percentile DAP levels outlined in this study can be used as baseline local diagnostic reference levels. The needs for the standardisation of DAP reporting and for a greater range of age-specific diagnostic reference levels have been highlighted. For the first time, Australian dose values for paediatric cardiac catheterisation are presented.
Publisher: SPIE
Date: 26-02-2009
DOI: 10.1117/12.813676
Publisher: Wiley
Date: 30-08-2019
DOI: 10.1002/ACM2.12711
Publisher: Radiological Society of North America (RSNA)
Date: 07-2013
Publisher: Elsevier BV
Date: 02-2013
DOI: 10.1016/J.EJRAD.2012.09.016
Abstract: To investigate enhancement of head and neck arteries during carotid computed tomography angiography using a reduced volume contrast regimen and craniocaudal scan acquisition. Two hundred and two patients underwent carotid angiography using a 64 channel computed tomography scanner. Patients were allocated to one of two acquisition/contrast regimens: regimen A, the department's standard protocol, consisting of a caudocranial scan direction with 100mL of contrast intravenously regimen B, involving a craniocaudal scan direction and approximately 50 mL of contrast using a timing dictated by patient hemodynamics. Attenuation profiles of cranial arteries and veins in 6 anatomical segments were assessed and arteriovenous contrast ratios (AVCR) calculated. Receiver operating characteristic (ROC) analysis was performed using DBM methodology. Arterial attenuation was up to 54% (p<0.01) higher following regimen B compared with A. Attenuation in the veins were significantly lower in regimen B than in regimen A with a maximum reduction of up to 93% (p<0.0001). With regimen B, there were significant (p<0.0001) improvements in AVCR at a variety of anatomical sites. The ROC analysis demonstrated a significantly higher Az score for the novel regimen compared with regimen A (p<0.002) with inter-neuroradiologist agreement increasing from poor to moderate. Significant improvements in visualisation of head and neck arterial vasculature can be achieved with a CT acquisition regimen using low contrast volume and injection timing based on patient specific contrast formula and craniocaudal scan direction.
Publisher: SPIE
Date: 22-05-2020
DOI: 10.1117/12.2564053
Publisher: Elsevier BV
Date: 05-2014
Publisher: American Roentgen Ray Society
Date: 04-2011
DOI: 10.2214/AJR.10.4681
Publisher: Springer Berlin Heidelberg
Date: 2012
Publisher: Springer Berlin Heidelberg
Date: 2012
Publisher: Elsevier BV
Date: 10-2020
Publisher: Springer Science and Business Media LLC
Date: 24-03-2005
DOI: 10.1007/S00330-004-2571-2
Abstract: The composition of protective aprons worn by X-ray personnel to shield against secondary radiation is changing. Lead is being replaced by either lead-free or composite (lead with other high atomic numbered elements) materials. These newer aprons are categorised by manufacturers in terms of lead equivalent values, but it is unclear how these stated values compare with actual lead equivalent values. In this work, the actual lead equivalence of 41 protective aprons from four manufacturers, all specified as having 0.25 mm lead equivalence, were investigated with transmission experiments at 70 and 100 kVp. All aprons were in current use. The aprons were screened for defects, and age, weight and design was recorded along with details of associated quality assurance (QA). Out of the 41 protective aprons examined for actual lead equivalence, 73% were outside tolerance levels, with actual levels in some aprons demonstrating less than half of the nominal values. The lack of compatibility between actual and nominal lead equivalent values was demonstrated by aprons from three of the four manufacturers investigated. The area of the defects found on screening of the protective aprons were within recommendations. The results highlight the need for acceptancy and ongoing checks of protective aprons to ensure that radiation exposure of imaging personnel is kept to a minimum.
Publisher: SPIE
Date: 17-03-2015
DOI: 10.1117/12.2081838
Publisher: Springer Science and Business Media LLC
Date: 16-03-2013
Publisher: Wiley
Date: 06-2010
DOI: 10.1118/1.3468104
Publisher: British Institute of Radiology
Date: 10-2015
DOI: 10.1259/BJR.20140340
Publisher: British Institute of Radiology
Date: 04-2019
DOI: 10.1259/BJR.20180793
Abstract: This study aimed to examine the associated factors for dose variation and influence cardiac CT angiography (CCTA) dose benchmarks in current CT imaging centres. A questionnaire was distributed to CT centres across Australia and Saudi Arabia. All participating centres collected data for adults who underwent a CCTA procedure. The questionnaire gathered information about the examination protocol, scanning parameters, patient parameters, and volume CT dose index (CTDI vol) and dose–length product (DLP). A stepwise regression analysis was performed to assess the contribution of tube voltage (kV), padding time technique, cross-sectional area (CSA) of chest and weight to DLP. A total of 17 CT centres provided data for 423 CCTA examinations. The median CTDI vol , DLP and effective dose were 18 mGy, 256 mGy.cm and 5.2 mSv respectively. There was a statistically significant difference in DLP between retrospective and prospective ECG-gating modes (p = 0.001). Median DLP from CCTA using padding technique was 61% higher than CCTA without padding (p = 0.001). The stepwise regression showed that kV was the most significant predictor of DLP followed by padding technique then CSA while patient weight did not statistically significantly predict DLP. Correlation analysis showed a strong positive correlation between weight and CSA (r = 0.78), and there was a moderate positive correlation between weight and DLP (r = 0.42), as well as CSA and DLP (r = 0.48). Findings show radiation dose variations for CCTA. The associated factors for dose variation found in this study are scanning mode, kV, padding time technique and CSA of the chest. This results support the need to include CSA measurements in future dose survey and for setting DRLs. The study provides baseline information that helps to understand the associated factors for dose variations and high doses within and between centres performing CCTA.
Publisher: SPIE
Date: 28-03-2013
DOI: 10.1117/12.2006781
Publisher: SPIE
Date: 26-02-2009
DOI: 10.1117/12.810993
Publisher: Elsevier BV
Date: 08-2009
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/J.CRAD.2012.02.007
Abstract: The purpose of this article is to review the limitations associated with current methods of assessing reader accuracy in mammography screening programmes. Clinical audit is commonly used as a quality-assurance tool to monitor the performance of screen readers however, a number of the metrics employed, such as recall rate as a surrogate for specificity, do not always accurately measure the intended clinical feature. Alternatively, standardized screening test sets, which benefit from ease of application, immediacy of results, and quicker assessment of quality improvement plans, suffer from experimental confounders, thus questioning the relevance of these laboratory-type screening test sets to clinical performance. Four key factors that impact on the external validity of screening test sets were identified: the nature and extent of scrutiny of one's action, the artificiality of the environment, the over-simplification of responses, and prevalence of abnormality. The impact of these factors on radiological and other contexts is discussed, and although it is important to acknowledge the benefit of standardized screening test sets, issues relating to the relevance of test sets to clinical activities remain. The degree of correlation between performance based on real-life clinical audit and performances at screen read test sets must be better understood and specific causal agents for any lack of correlation identified.
Publisher: Elsevier BV
Date: 09-2015
DOI: 10.1016/J.JMIR.2015.06.015
Abstract: Multifocal basal ganglia T2-weighted hypointensities are believed to arise mainly from mineralization in and around penetrating arteries and perivascular spaces within gray and white matter structures. Recently, it has been proposed that these hypointensities can serve as a biomarker for small-vessel disease and aging in magnetic resonance imaging when using T2-weighted sequences. With advances in digital coil technology and parameter applications, there has been an increase in image quality and faster examination times. However, artifacts related to higher-field strengths (3.0 T) are reducing image quality. This case report demonstrates reduced focal hypointensities in the basal ganglia by using concentric rectangular blades rotated around the k-space origin to reduce artifacts at 3.0 T.
Publisher: American Roentgen Ray Society
Date: 08-2011
DOI: 10.2214/AJR.10.4569
Abstract: The purpose of this study was to prospectively evaluate the effect of cranial breast displacement and lead shielding on in vivo breast surface radiation dose in women undergoing coronary CT angiography. Fifty-four women (mean age, 59.2 ± 9.8 years) prospectively underwent coronary 64-MDCT angiography for evaluation of chest pain. The patients were randomly assigned to a control group (n = 16), breast displacement group (n = 22), or breast displacement plus lead shielding group (n = 16). Thermoluminescent dosimeters (TLDs) were placed superficially on each breast quadrant and the areolar region of both breasts. Breast surface radiation doses, the degree of breast displacement, and coronary image quality were compared between groups. A phantom dose study was conducted to compare breast doses with z-axis positioning on the chest wall. A total of 1620 TLD dose measurements were recorded. Compared with control values, the mean breast surface dose was reduced 23% in the breast displacement group (24.3 vs 18.6 mGy, p = 0.015) and 36% in the displacement plus lead shielding group (24.3 vs 15.6 mGy, p = 0.0001). Surface dose reductions were greatest in the upper outer (displacement alone, 66% displacement plus shielding, 63%), upper inner (65%, 58%), and areolar quadrants (44%, 53%). The smallest surface dose reductions were recorded for A-cup breasts: 7% for the displacement group and 3% for the displacement plus lead group (p = 0.741). Larger reductions in surface dose were recorded for B-cup (25% and 56%, p = 0.273), C-cup (38% and 60%, p = 0.001), and D-cup (31% and 25%, p = 0.095) sizes. Most of the patients (79%) had either good (< 50% of breast above scan range) or excellent (< 75% of breast above the scan range) breast displacement. No significant difference in coronary image quality was detected between groups. The phantom dose study showed that surface TLD measurements were underestimates of absorbed tissue dose by a mean of 9% and that a strong negative correlation exists between the amount of cranial displacement and breast dose. Use of breast displacement during coronary CTA substantially reduces the radiation dose to the breast surface.
Publisher: SPIE
Date: 06-03-2008
DOI: 10.1117/12.769464
Publisher: Springer International Publishing
Date: 2014
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.ACRA.2018.07.008
Abstract: This study employs clinical/radiological evaluation in establishing the optimum imaging conditions for breast cancer imaging using the X-ray propagation-based phase-contrast tomography. Two series of experiments were conducted and in total 161 synchrotron-based computed tomography (CT) reconstructions of one breast mastectomy specimen were produced at different imaging conditions. Imaging factors include s le-to-detector distance, X-ray energy, CT reconstruction method, phase retrieval algorithm applied to the CT projection images and maximum intensity projection. Observers including breast radiologists and medical imaging experts compared the quality of the reconstructed images with reference images approximating the conventional (absorption) CT. Various radiological image quality attributes in a visual grading analysis design were used for the radiological assessments. The results show that the application of the longest achievable s le-to-detector distance (9.31 m), the lowest employed X-ray energy (32 keV), the full phase retrieval, and the maximum intensity projection can significantly improve the radiological quality of the image. Several combinations of imaging variables resulted in images with very high-quality scores. The results of the present study will support future experimental and clinical attempts to further optimize this innovative approach to breast cancer imaging.
Publisher: SPIE
Date: 24-03-2016
DOI: 10.1117/12.2216626
Publisher: Elsevier BV
Date: 11-2018
DOI: 10.1016/J.COMPBIOMED.2018.09.020
Abstract: To investigate the knowledge and practice of computed tomography (CT) radiographers working in Jordan. This Institutional Review Board (IRB) approved study disseminated a questionnaire via social media and recruited 54 Jordanian CT radiographers. The questionnaire comprised 36 questions ided into four sections: demographics an evaluation of knowledge regarding CT exposure modifications to CT exposure for paediatric patients dose units and diagnostic reference levels (DRLs). Descriptive and inferential statistics including Chi-square tests, Mann-Whitney U tests, independent s les t-tests and Kruskal-Wallis H tests were employed. Statistical significance was considered below p < 0.05. The 54 participants had various qualifications, with the majority holding a Bachelor's degree (n = 35, 64.8%) and the rest holding a Diploma (n = 19, 35.2%). In order to pass the questionnaire, participants needed to score 13 correct answers. The overall number of radiographers who correctly passed the questionnaire was 48 (88.9%). None of the participants correctly stated all the DRL values for chest, abdomen and brain CT. However, four out of 54 respondents (7.4%) knew the chest DRL value, three (5.6%) participants correctly estimated the abdominal DRL value but only two (3.7%) knew the DRL for the brain. Good general knowledge was found amongst radiographers regarding the relationship of each exposure parameter to the image quality and patient dose. However, there was poor knowledge of diagnostic reference levels and the order of the organ radiation sensitivity. The need for CT radiographers to undertake further education that focuses on radiation exposure in CT is highlighted.
Publisher: Wiley
Date: 16-05-2018
DOI: 10.1002/MP.12935
Abstract: The purpose of this study was to Propose a classifier based on recurrence quantification analysis (RQA) metrics for distinguishing experts' scanpaths from those of less-experienced readers and to explore the association of spatiotemporal dynamics of the mammographic scanpaths with the characteristics of cases and radiologists using RQA metrics. Eye movements were recorded from eight radiologists (two cohorts: four experienced and four less-experienced) while reading 120 mammograms (59 cancer, 61 normal). Ten RQA measures were extracted for each recorded scanpath. The measures described the temporal distribution of recurrent fixations as well as laminar and deterministic eye movements. Recurrent fixations are fixations that are located close to a previously fixated point in a scanpath. Deterministic eye movements represent looking back and forth between two locations, while laminar eye movements indicate detailed scanning of an area with consecutive fixations. The RQA metrics along with six conventional eye-tracking parameters were used to construct a classifier for distinguishing experts' scanpaths from those of less-experienced readers. Leave-one-out cross validation was used for evaluating the classifier. For each reader cohort, the ANOVA analysis was done to study the relationship of RQA measures with breast density, case pathology, readers' expertise, and readers' decisions on the case. The proportions of laminar and deterministic movements involved fixations in the location of lesions were also compared for two reader cohorts using two proportion z-tests. All RQA measures differed significantly between scanpaths of experienced readers and those of less-experienced readers. The classifier achieved an area under the receiver operating characteristic curve of 0.89 (0.87-0.91) for detecting experts' scanpaths. Proportionately more refixations and laminar and deterministic sequences were in the location of the lesion for the experienced cohort compared to the less-experienced cohort (all P-values < 0.001). Eight and four RQA measures differed between normal and cancer cases for the experienced and less experienced readers, respectively. None of metrics differed between fatty and dense breasts for the less experienced readers, while two measures resulted into a significant difference for the experienced readers. For experts, six measures differed significantly between true negatives and false positives and nine were significantly different between true positives and false negatives. For the less-experienced cohort, the corresponding figures were seven and one measures, respectively. The RQA measures can quantify the differences among experienced and less experienced radiologists. They also capture differences among experts' scanpaths related to case pathology and radiologists' decisions on the case.
Publisher: SPIE
Date: 04-03-2010
DOI: 10.1117/12.845254
Publisher: Elsevier BV
Date: 06-2017
DOI: 10.1016/J.CRAD.2017.01.002
Abstract: Lung cancer is the leading cause of cancer-related death worldwide however, early diagnosis of lung cancer leads to higher survival rates. The National Lung Screening Trial (NLST) demonstrated that scanning with low-dose computed tomography (LDCT) led to a 20% reduction in mortality rate in a high-risk population. This paper covers new developments in screening eligibility criteria and the possible benefits and the harm of screening with CT. To make the screening process more feasible and help reduce the rate of missed lung nodules, computer-aided detection (CAD) has been introduced to assist radiologists in lung nodule detection. The aim of this paper is to review how CAD works, its performance in lung nodule detection, and the factors that influence its performance. This paper also aims to investigate the effect of different types of CAD on CT in lung nodule detection and the effect of CAD on radiologists' decision outcomes.
Publisher: SPIE
Date: 17-03-2015
DOI: 10.1117/12.2081725
Publisher: Oxford University Press (OUP)
Date: 16-05-2005
DOI: 10.1093/RPD/NCH474
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.CLINIMAG.2019.01.002
Abstract: Improved mammographic sensitivity is associated with reduced mammographic density. This study aims to: provide a preliminary report on mammographic density among women in Riyadh identify risk factors associated with mammographic density and consider the potential implications for screening practices. Based on a cross-sectional design, we examined a total of 792 women using an area-based mammographic density method (LIBRA). Spearman's correlation, Mann-Whitney U, Kruskal-Wallis and binary logistic regression were used for analyses. The study population had a mean age of 49.6 years and a high proportion of participants were overweight or obese (90%). A large number of women had low mammographic density, with a mean dense breast area of 19.1 cm Given the high proportion of women with low mammographic density, our findings suggest that women living in Riyadh may not require additional imaging strategies beyond mammography to detect breast cancers. The high proportion of obese women reported here and across Saudi Arabia suggests that mammographic density is less likely to have an adverse impact on mammographic sensitivity. Thus and to improve clinical outcomes among Saudi women, annual mammography and commencing screening at a younger age are suggested. Additional studies are required to shed further light on our findings.
Publisher: American Roentgen Ray Society
Date: 02-2010
DOI: 10.2214/AJR.09.3418
Publisher: SPIE
Date: 26-02-2009
DOI: 10.1117/12.810748
Publisher: British Institute of Radiology
Date: 04-2009
DOI: 10.1259/BJR/14857366
Abstract: Collective dose for cardio-angiography studies is the highest of all non-CT radiological investigations. Deterministic effects such as erythema, epilation and ulceration being reported on patients who have undergone these procedures emphasise the importance of optimising radiation dose, whilst not compromising diagnostic efficacy. This study investigated radiation doses delivered to patients for four common types of cardiac radiological examinations: coronary angiography (CA), percutaneous coronary intervention (PCI), coronary angiograms (which were followed by an interventional procedure (CA-PCI)) and permanent pacemaker insertions (PPIs). 21 cardiac imaging suites participated in the study in 14 hospitals, representing 90% of relevant centres within Ireland. Radiation dose was monitored for 1804 adult patients using dose-area product meters. Operational and examination details, such as cardiologist grade, patient details, examination complexity and exposure factors, were recorded for each examination. Variation factors in dose between centres ranged from 2.7 to 11.1, but these factors were not higher than intrahospital variations previously recorded for other examinations within Ireland, such as chest X-ray. High-dose centres were often associated with long screening times, a high patient body mass index and complexity of the procedure. Preliminary dose reference levels (DRLs) were established using rounded third quartile values at 4200 cGy cm(2), 8400 cGy cm(2), 10,700 cGy cm(2) and 2100 cGy cm(2) for CA, PCI, CA-PCI and PPI, respectively. With these commonly performed relatively high-dose procedures, it is important that some guideline values are available to encourage optimised strategies. These proposed DRLs offer such guidance.
Publisher: SPIE
Date: 11-03-2014
DOI: 10.1117/12.2042828
Publisher: Elsevier BV
Date: 06-2009
Publisher: Elsevier BV
Date: 12-2013
DOI: 10.1016/J.JMIR.2013.07.002
Abstract: This investigation proposes that an increased source to the image-receptor distance (SID) technique can be used to optimize occipital frontal and lateral cranial radiographs acquired with direct digital radiography. Although cranial radiography is not performed on a routine basis, it should nonetheless be optimized to keep the dose to the patient as low as reasonably achievable, particularly because it can form part of the facial bone and sinus series. Dose measurements were acquired at various SIDs, and image quality was assessed using visual grading analysis. Statistically significant reductions in the effective dose between 19.2% and 23.9% were obtained when the SID was increased from the standard 100 to 150 cm (P ≤ .05), and visual grading analysis scores indicate that image quality remained diagnostically acceptable for both projections. This investigation concludes that increasing the SID effectively optimizes occipital frontal and lateral skull radiographs. Radiology departments must be advised of the benefits of this technique with the goal of introducing an updated reference SID of 150 cm into clinical practice.
Publisher: Elsevier BV
Date: 02-2010
Publisher: SPIE-Intl Soc Optical Eng
Date: 11-08-2018
Publisher: Elsevier BV
Date: 05-2018
DOI: 10.1016/J.COMPBIOMED.2018.04.005
Abstract: While there is much literature describing the radiologic detection of breast cancer, there are limited data available on the agreement between experts when delineating and classifying breast lesions. The aim of this work is to measure the level of agreement between expert radiologists when delineating and classifying breast lesions as demonstrated through Breast Imaging Reporting and Data System (BI-RADS) and quantitative shape metrics. Forty mammographic images, each containing a single lesion, were presented to nine expert breast radiologists using a high specification interactive digital drawing tablet with stylus. Each reader was asked to manually delineate the breast masses using the tablet and stylus and then visually classify the lesion according to the American College of Radiology (ACR) BI-RADS lexicon. The delineated lesion compactness and elongation were computed using Matlab software. Intraclass Correlation Coefficient (ICC) and Cohen's kappa were used to assess inter-observer agreement for delineation and classification outcomes, respectively. Inter-observer agreement was fair for BI-RADS shape (kappa = 0.37) and moderate for margin (kappa = 0.58) assessments. Agreement for quantitative shape metrics was good for lesion elongation (ICC = 0.82) and excellent for compactness (ICC = 0.93). Fair to moderate levels of agreement was shown by radiologists for shape and margin classifications of cancers using the BI-RADS lexicon. When quantitative shape metrics were used to evaluate radiologists' delineation of lesions, good to excellent inter-observer agreement was found. The results suggest that qualitative descriptors such as BI-RADS lesion shape and margin understate the actual level of expert radiologist agreement.
Publisher: SPIE
Date: 08-03-2007
DOI: 10.1117/12.708216
Publisher: British Institute of Radiology
Date: 2013
DOI: 10.1259/BJR/42313554
Publisher: SAGE Publications
Date: 07-2017
Abstract: The aim of this study was to investigate how breast density interacted with demographic, reproductive, and lifestyle features among Vietnamese women. Mammographic density and established risk factors for breast cancer were collected from 1651 women (345 cancer cases and 1306 normal cases) in Vietnam. The association of breast density categories with potential risk factors was investigated using Spearman's test for continuous variables and χ
Publisher: Elsevier BV
Date: 08-2007
Publisher: Elsevier BV
Date: 05-2013
DOI: 10.1016/J.ACRA.2012.12.010
Abstract: To identify specific mammographic appearances that reduce the mammographic detection of breast cancer. This study received institutional board review approval and all readers gave informed consent. A set of 60 mammograms each consisting of craniocaudal and mediolateral oblique projections were presented to 129 mammogram Breastscreen readers. The images consisted of 20 positive cases with single and multicentric masses in 16 and 4 cases, respectively (resulting in a total of 24 cancers), and readers were asked to identify and locate the lesions. Each lesion was then ranked according to a detectability rating (ie, the number of observers who correctly located the lesion ided by the total number of observers), and this was correlated with breast density, lesion size, and various descriptors of lesion shape and texture. Negative and positive correlations between lesion detection and density (r = -0.64, P = .007) and size (r = 0.65, P = .005), respectively, were demonstrated. In terms of lesion size and shape, there were significant correlations between the probability of detection and area (r = 0.43, P = .04), perimeter (r = 0.66, P = .0004), lesion elongation (r = 0.49, P = .02), and lesion nonspiculation (r = 0.78, P < .0001). The results of this study have identified specific lesion characteristics associated with shape that may contribute to reduced cancer detection. Mammographic sensitivity may be adversely affected without appropriate attention to spiculation.
Publisher: British Institute of Radiology
Date: 04-2016
DOI: 10.1259/BJR.20151057
Publisher: SPIE
Date: 03-03-2011
DOI: 10.1117/12.877918
Publisher: SPIE
Date: 03-03-2011
DOI: 10.1117/12.877917
Publisher: IOP Publishing
Date: 24-02-2017
Abstract: The aim of this study was to optimise the experimental protocol and data analysis for in-vivo breast cancer x-ray imaging. Results are presented of the experiment at the SYRMEP beamline of Elettra Synchrotron using the propagation-based phase-contrast mammographic tomography method, which incorporates not only absorption, but also x-ray phase information. In this study the images of breast tissue s les, of a size corresponding to a full human breast, with radiologically acceptable x-ray doses were obtained, and the degree of improvement of the image quality (from the diagnostic point of view) achievable using propagation-based phase-contrast image acquisition protocols with proper incorporation of x-ray phase retrieval into the reconstruction pipeline was investigated. Parameters such as the x-ray energy, s le-to-detector distance and data processing methods were tested, evaluated and optimized with respect to the estimated diagnostic value using a mastectomy s le with a malignant lesion. The results of quantitative evaluation of images were obtained by means of radiological assessment carried out by 13 experienced specialists. A comparative analysis was performed between the x-ray and the histological images of the specimen. The results of the analysis indicate that, within the investigated range of parameters, both the objective image quality characteristics and the subjective radiological scores of propagation-based phase-contrast images of breast tissues monotonically increase with the strength of phase contrast which in turn is directly proportional to the product of the radiation wavelength and the s le-to-detector distance. The outcomes of this study serve to define the practical imaging conditions and the CT reconstruction procedures appropriate for low-dose phase-contrast mammographic imaging of live patients at specially designed synchrotron beamlines.
Publisher: Oxford University Press (OUP)
Date: 23-01-2017
DOI: 10.1093/RPD/NCX003
Abstract: This study examines the cumulative radiation dose levels received by a group of children who underwent multiple cardiac catheterisation procedures during the investigation and management of congenital heart disease (CHD). The purpose is to calculate cumulative doses, identify higher dose in iduals, outline the inconsistencies with risk assessment and encourage the establishment of dose databases in order to facilitate the longitudinal research necessary to better understand health risks. A retrospective review of patient records for 117 paediatric patients who have undergone two or more cardiac catheterisations for the investigation of CHD was undertaken. This cohort consisted of patients who were catheterised over a period from September 2002 to August 2014. The age distribution was from newborn to 17 y. Archived kerma-area product (PKA) and fluoroscopy time (T) readings were retrieved and analysed. Cumulative effective and in idual organ doses were determined. The cumulative PKA levels ranged from 1.8 to 651.2 Gycm2, whilst cumulative effective dose levels varied from 2 to 259 mSv. The cumulative fluoroscopy time was shown to vary from 8.1 to 193.5 min. Median cumulative organ doses ranged from 3 to 94 mGy. Cumulative effective dose levels are highly variable but may exceed 250 mSv. In idual organ and effective dose measurements remain useful for comparison purposes between institutions although current methodologies used for determining lifetime risks are inadequate.
Publisher: SPIE
Date: 08-03-2007
DOI: 10.1117/12.714173
Publisher: Elsevier BV
Date: 06-2020
Publisher: SPIE
Date: 10-03-2017
DOI: 10.1117/12.2254527
Publisher: SPIE
Date: 16-03-2020
DOI: 10.1117/12.2549921
Publisher: SPIE
Date: 24-03-2016
DOI: 10.1117/12.2216020
Publisher: Springer Science and Business Media LLC
Date: 25-08-2016
DOI: 10.1007/S10549-016-3947-0
Abstract: Breast cancer is the most common neoplasm diagnosed amongst women worldwide and is the leading cause of female cancer death. However, breast cancer in China is not comprehensively understood compared with Westernised countries, although the 5-year prevalence statistics indicate that approximately 11 % of worldwide breast cancer occurs in China and that the incidence has increased rapidly in recent decades. This paper reviews the descriptive epidemiology of Chinese breast cancer in terms of incidence, mortality, survival and prevalence, and explores relevant factors such as age of manifestation and geographic locations. The statistics are compared with data from the Westernised world with particular emphasis on the United States and Australia. Potential causal agents responsible for differences in breast cancer epidemiology between Chinese and other populations are also explored. The need to minimise variability and discrepancies in methods of data acquisition, analysis and presentation is highlighted.
Publisher: EpiSmart Science Vector Ltd
Date: 09-2020
Publisher: SAGE Publications
Date: 11-2009
DOI: 10.3109/02841850903147053
Abstract: Background: Image quality and radiation dose to the patient are important factors in computed tomography (CT). To provide constant image quality, tube current modulation (TCM) performed by automatic exposure control (AEC) adjusts the tube current to the patient's size and shape. Purpose: To evaluate the effects of patient centering on tube current–time product (mAs) and image noise. Material and Methods: An oval-shaped acrylic phantom was scanned in various off-center positions, at 30-mm intervals within a 500-mm field of view, using three different CT scanners. Acquisition parameters were similar to routine abdomen examinations at each site. The mAs was recorded and noise measured in the images. The correlation of mAs and noise with position was calculated using Pearson correlation. Results: In all three scanners, the mAs delivered by the AEC changed with y-position of the phantom ( P .001), with correlation values of 0.98 for scanners A and B and −0.98 for scanner C. With x-position, mAs changes were 4.9% or less. As the phantom moved into the y-positions, compared with the iso-center, the mAs varied by up to +70%, −34%, and +56% in scanners A, B, and C, respectively. For scanners A and B, noise in two regions of interest in the lower part of the phantom decreased with elevation, with correlation factors from −0.95 to −0.86 ( P .02). In the x-direction, significant noise relationships ( P .005) were only seen in scanner A. Conclusion: This study demonstrates that patient centering markedly affects the efficacy of AEC function and that tube current changes vary between scanners. Tube position when acquiring the scout projection radiograph is decisive for the direction of the mAs change. Off-center patient positions cause errors in tube current modulation that can outweigh the dose reduction gained by AEC use, and image quality is affected.
Publisher: SPIE
Date: 24-03-2016
DOI: 10.1117/12.2217475
Publisher: Springer Science and Business Media LLC
Date: 15-01-2016
DOI: 10.1007/S00330-015-4194-1
Abstract: To determine the impact of specific reporting tasks on the performance of radiologists when reading chest radiographs. Ten experienced radiologists read a set of 40 postero-anterior (PA) chest radiographs: 21 nodule free and 19 with a proven solitary nodule. There were two reporting conditions: an unframed task (UFT) to report any abnormality and a framed task (FT) reporting only lung nodule/s. Jackknife free-response operating characteristic (JAFROC) figure of merit (FOM), specificity, location sensitivity and number of true positive (TP), false positive (FP), true negative (TN) and false negative (FN) decisions were used for analysis. JAFROC FOM for tasks showed a significant reduction in performance for framed tasks (P = 0.006) and an associated decrease in specificity (P = 0.011) but no alteration to the location sensitivity score. There was a significant increase in number of FP decisions made during framed versus unframed tasks for nodule-containing (P = 0.005) and nodule-free (P = 0.011) chest radiographs. No significant differences in TP were recorded. Radiologists report more FP decisions when given specific reporting instructions to search for nodules on chest radiographs. The relevance of clinical history supplied to radiologists is called into question and may induce a negative effect. • Framed reporting tasks increases false positive rates when searching for pulmonary nodules • False positive results were observed in both nodule-containing and nodule-free cases • Radiologist's decision-making may be influenced by clinical history in thoracic imaging.
Publisher: SPIE
Date: 06-03-2008
DOI: 10.1117/12.769685
Publisher: SPIE
Date: 17-03-2015
DOI: 10.1117/12.2082662
Publisher: Wiley
Date: 06-04-2016
Abstract: The detection of breast cancer is somewhat limited by human factors, and thus there is a need to improve reader performance. This study assesses whether radiologists who regularly undertake the education in the form of the Breast Reader Assessment Strategy (BREAST) demonstrate any changes in mammography interpretation performance over time. In 2011, 2012 and 2013, 14 radiologists independently assessed a year-specific BREAST mammographic test-set. Radiologists read a different single test-set once each year, with each comprising 60 digital mammogram cases. Radiologists marked the location of suspected lesions without computer-aided diagnosis (CAD) and assigned a confidence rating of 2 for benign and 3-5 for malignant lesions. The mean sensitivity, specificity, location sensitivity, JAFROC FOM and ROC AUC were calculated. A Kruskal-Wallis test was used to compare the readings for the 14 radiologists across the 3 years. Wilcoxon signed rank test was used to assess comparison between pairs of years. Relationships between changes in performance and radiologist characteristics were examined using a Spearman's test. Significant increases were noted in mean sensitivity (P = 0.01), specificity (P = 0.01), location sensitivity (P = 0.001) and JAFROC FOM (P = 0.001) between 2011 and 2012. Between 2012 and 2013, significant improvements were noted in mean sensitivity (P = 0.003), specificity (P = 0.002), location sensitivity (P = 0.02), JAFROC FOM (P = 0.005) and ROC AUC (P = 0.008). No statistically significant correlations were shown between the levels of improvement and radiologists' characteristics. Radiologists' who undertake the BREAST programme demonstrate significant improvements in test-set performance during a 3-year period, highlighting the value of ongoing education through the use of test-set.
Publisher: SPIE
Date: 23-02-2012
DOI: 10.1117/12.913646
Publisher: Wiley
Date: 15-08-2014
Abstract: The purpose of this work was to determine the exposure-optimised slice thickness for hepatic lesion detection with CT. A phantom containing spheres (diameter 9.5, 4.8 and 2.4 mm) with CT density 10 HU below the background (50 HU) was scanned at 125, 100, 75 and 50 mAs. Data were reconstructed at 5-, 3- and 1-mm slice thicknesses. Noise, contrast-to-noise ratio (CNR), area under the curve (AUC) as calculated using receiver operating characteristic analysis and sensitivity representing lesion detection were calculated and compared. Compared with the 125 mAs/5 mm slice thickness setting, significant reductions in AUC were found for 75 mAs (P < 0.01) and 50 mAs (P < 0.05) at 1- and 3-mm thicknesses, respectively sensitivity for the 9.5-mm sphere was significantly reduced for 75 (P < 0.05) and 50 mAs (P < 0.01) at 1-mm thickness sensitivity for the 4.8-mm sphere was significantly lower for 100, 75 and 50 mAs at all three slice thicknesses (P < 0.05). The 2.4-mm sphere was rarely detected. At each slice thickness, noise at 100, 75 and 50 mAs exposures was approximately 10, 30 and 50% higher, respectively, than that at 125 mAs exposure. CNRs decreased in an irregular manner with reductions in exposure and slice thickness. This study demonstrated no advantage to using slices below 5 mm thickness, and consequently thinner slices are not necessarily better.
Publisher: Elsevier BV
Date: 05-2013
DOI: 10.1016/J.CLINIMAG.2012.07.001
Abstract: Cirsoid aneurysms of the scalp are a rare abnormality with severe cosmetic deformity and possibly of severe hemorrhage. They present as a diagnostic and management challenge, but evaluation with multidetector computed tomography is useful in the diagnosis and treatment planning of these clinically complex disorders of the extracranial circulation. We present a case report of a 38-year-old New Caledonian male who had a large pulsatile mass in his scalp, which had progressively increased in size since the age of 17 years. The clinical and imaging features are outlined, in addition to treatment and prognosis.
Publisher: SPIE
Date: 04-03-2019
DOI: 10.1117/12.2513151
Publisher: Oxford University Press (OUP)
Date: 22-08-2018
DOI: 10.1093/RPD/NCY113
Abstract: The aim of this systematic review is to investigate the national diagnostic reference level (NDRL) methods for positron emission tomography/computed tomography (PET/CT) and single photon emission tomography/computed tomography (SPECT/CT) procedures. A search strategy was based on the preferred, reporting items for systematic review and meta-analysis (PRISMA). Relevant articles retrieved from Medline, Scopus, Web of Science, Embase, Cinahl, and Google Scholar published up to October 2017. The search yielded 1057 articles. Fourteen articles were included in the review after a screening process. Relevant information from the selected articles were summarised and analysed. Discrepancies were found between the methodologies utilised to establish and report both PET/CT and SPECT/CT NDRLs, e.g. patient s ling and administered activity. Further research should focus on reporting more NDRLs for hybrid PET/CT and SPECT/CT examinations, and establish a robust NDRL standard for the CT portion associated with PET/CT and SPECT/CT examinations. This review provides updated NDRL reommndations to deliver more comparable international radation doses for administered activity and CT dose across PET/CT and SPECT/CT clinics.
Publisher: Oxford University Press (OUP)
Date: 19-07-2018
DOI: 10.1093/RPD/NCY112
Abstract: This study aims to assess patient radiation dose from cardiac computed tomography angiography (CCTA) with the aim of proposing a national diagnostic reference levels (NDRLs) for CCTA procedures in Australia. A questionnaire was used to retrospectively gather baseline information related to CCTA scanning and patient parameters in CT centres across the country. The 75th percentile of both volumetric CT dose index (CTDIvol) and dose length-product (DLP) was used as DRL values for CCTA. A DRL for CT calcium scoring test was also determined. NDRLs were compared with international published data. Data sets of 338 patients from nine CT centres were used for analysis. The CCTA DRL for the CTDIvol and the DLP were 22 mGy and 268 mGy cm, respectively. The CT calcium scoring test DRL for DLP was 137 mGy cm. The DRL values for CCTA in Australia have been recommended for the first time. DRLs are lower than those in most published studies due to the implementation of dose-saving technologies such as prospective ECG-gated mode and iterative reconstruction algorithms. Considerable variations remain in patient doses between hospitals for the most frequently used CCTA protocols, indicating the potential for DRLs to prompt dose optimisation strategies in CT facilities.
Publisher: SPIE
Date: 28-03-2013
DOI: 10.1117/12.2007760
Publisher: SPIE
Date: 08-03-2007
DOI: 10.1117/12.706772
Publisher: Springer Science and Business Media LLC
Date: 14-05-2013
Publisher: British Institute of Radiology
Date: 07-2014
DOI: 10.1259/BJR.20140029
Publisher: SPIE
Date: 22-03-2016
DOI: 10.1117/12.2216492
Publisher: SAGE Publications
Date: 23-04-2020
Abstract: Authentic student-led inquiry and exposure to scientific research impact students’ science career choices. Given Australian students decline in STEM skills, knowledge of whether such programmes impact student learning is critical. This research examined the short-term impact of an authentic, hands-on research mentor programme on rural student’s science skills. Nine Year 10 students participated in a science academic research programme leading to scientific publications and students collecting of first-hand data from international experiments on a major world-wide health issue. The NSW Department of Education Year 10 VALID assessment scores of this intervention group were compared to a control group. Intervention students had significantly higher overall scores as well as significantly higher scores in 21st century skills. These results were supported by student’s self-assessment of their learning growth. Our study suggests authentic science research mentor programmes are pedagogically advantageous for Year 10 high achieving rural students. Educators’ willingness to embrace these innovative approaches has the potential to produce the next generation of scientists.
Publisher: Springer Science and Business Media LLC
Date: 24-09-2019
DOI: 10.1038/S41598-019-50075-6
Abstract: In this study we demonstrate the first direct comparison between synchrotron x-ray propagation-based CT (PB-CT) and cone-beam breast-CT (CB-CT) on human mastectomy specimens (N = 12) including different benign and malignant lesions. The image quality and diagnostic power of the obtained data sets were compared and judged by two independent expert radiologists. Two cases are presented in detail in this paper including a comparison with the corresponding histological evaluation. Results indicate that with PB-CT it is possible to increase the level of contrast-to-noise ratio (CNR) keeping the same level of dose used for the CB-CT or achieve the same level of CNR reached by CB-CT at a lower level of dose. In other words, PB-CT can achieve a higher diagnostic potential compared to the commercial breast-CT system while also delivering a considerably lower mean glandular dose. Therefore, we believe that PB-CT technique, if translated to a clinical setting, could have a significant impact in improving breast cancer diagnosis.
Publisher: SPIE
Date: 23-02-2012
DOI: 10.1117/12.911586
Publisher: Elsevier BV
Date: 09-2009
DOI: 10.1016/J.JMIR.2009.06.004
Abstract: This study examines the performance of a selection (n = 33) of cathode ray tube monitors used in radiology. Previously published quality assurance tests and standards are used and evaluated and the data provided were used to determine the utility of each test. Recommendations for a program of consistency analysis suitable for imaging departments using cathode ray tube devices are made. The tests included in this study are: examination of the ambient viewing environment calibration of the monitor to the Digital Imaging and Communications in Medicine Grayscale Standard Display Function and assessment of image quality using a selection of American Association of Physicists in Medicine Task Group 18 (TG18) test patterns. Cathode ray tube monitor performance was seen to vary across departments and nonadherence to international standards for specific parameters was noted. On the basis of the results, a program for consistency analysis was recommended. Ambient light levels should be assessed using a photometer. Calibration of workstation monitors should be completed on a quarterly basis. Comprehensive image quality analysis using the TG18-Quality Control test pattern that facilitates the investigation of a number of quality parameters must be assessed at parameter-specific intervals. This should be supplemented with the TG18-Glare Visual test pattern for an assessment of veiling glare. Implementation of the recommendations above should enhance diagnostic efficacy and subsequent patient management.
Publisher: Wiley
Date: 21-03-2016
Abstract: Diagnostic error in radiology is not uncommon, with rates of clinically significant error reported to be as high as 20%. Radiological errors are often multifactorial, however, perceptual factors are thought to be mainly responsible. One way of reducing perceptual error is that of double reporting, which refers to the interpretation of radiological investigations by two observers, with strategies of arbitration and consensus available to settle discordant reports. Independent double reporting, where observers have no knowledge of each other's reports, is generally considered to be the most effective form. The impact of double reporting on diagnostic efficacy has been primarily explored in screening mammography, where it has consistently been shown to improve sensitivity, cancer detection rate and depending on local policy, have a positive influence on recall rates. Subsequently, the adoption of double reporting is reported as standard practice in many national and regional breast cancer-screening programmes. To a lesser extent, the impact of double reporting has also been investigated for neuroradiology, thoracic and gastrointestinal imaging, with small-scale studies in these fields showing promising results. With the widespread implementation of digitisation and the ease of access to images, the efficacy and cost-effectiveness of double reporting for other common radiological investigations requires attention. The review will evaluate the evidence regarding the effect of double interpretation of diagnostic imaging studies on test accuracy.
Publisher: Elsevier BV
Date: 10-2016
DOI: 10.1016/J.JPAIN.2016.06.008
Abstract: Migraine is prevalent and disabling yet is poorly understood. One way to better understand migraine is to examine its clinical characteristics and potential biomarkers such as gamma-aminobutyric acid (GABA). The primary objective of this study was to explore whether relevant disease characteristics of migraine are associated with brain GABA levels. Twenty adults fulfilling the established diagnostic criteria for migraine and 20 age- and gender-matched controls completed this cross-sectional study. Pain, central sensitization, negative emotional state, and perceived disability were measured using Short-form McGill Pain Questionnaire-2, Central Sensitization Inventory, Depression Anxiety Stress Scales-21, and Headache Impact Test-6, respectively. Secondary analysis of brain GABA levels of the same cohort measured using proton magnetic resonance spectroscopy was conducted. The migraine group had significantly higher scores than the control group on pain, central sensitization, and disability. Correlation analyses showed fair positive association between GABA levels and pain and central sensitization scores. No association was found between GABA levels and emotional state and disability. These findings are preliminary evidence supporting the use of questionnaires and GABA levels in characterizing migraine better and broadening the diagnostic process. These findings also strengthen the rationale for the role of GABA in migraine pathophysiology and corroborate the potential of GABA as a migraine biomarker. Higher pain and central sensitization scores were associated with increased brain GABA levels in in iduals with migraine. These findings offer preliminary evidence for the usefulness of measuring pain and central sensitization in migraine and provide some support for the possible role of GABA in migraine pathophysiology and its potential as a diagnostic marker.
Publisher: British Institute of Radiology
Date: 04-2019
DOI: 10.1259/BJR.20180879
Abstract: The aim of this study is to report a local diagnostic reference level (DRL) for paediatric whole-body (WB) fludeoxyglucose ( 18 F-FDG) positron emission tomography (PET) CT examinations. The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) national DRL (NDRL) age category (0–4 years and 5–14 years), the International Commission on Radiological Protection age category (ICRP age) ( , –5, –10, and –15 years), and European guideline weight category ( EG weight) ( , 5– , 15– , 30– , and 50– kg) were used to determine a local DRL for WB 18 F FDG PET/CT studies. Two-structured questionnaires were designed to collect dose data, patient demographics, equipment details, and acquisition protocols for WB 18 F-FDG PET/CT procedures. The local DRL was based on the median 18 F-FDG administered activity (MBq), dose–length product (DLP), and the CT dose index volume (CTDI vol ), values. The effective dose (E) was also calculated and reported. The local DRLs for 18 F-FDG administered activity, CTDI vol and DLP values based on ARPANSA age and ICRP age were increased from lower to higher age categories. For the EG weight category, the local DRL for 18 F-FDG administered activity, CTDI vol and DLP values were increased from the low EG weight category to the high EG weight category. The mean administered activity in our study based on ICRP age category –5, –10, and –15 years is 79.97, 119.40, and 176.04 MBq, which is lower than the mean administered activity reported in the North American Consensus guideline published in 2010 (99, 166, and 286 MBq) and European Association of Nuclear Medicine and Dosage Card (version 1.5.2008) (120, 189, and 302 MBq). However, the mean administered activity in our study based on ICRP age category year was 55 MBq compared to the EANM Dosage card (version 1.5.2008) (70 MBq) and the NACG 2010 (51 MBq). Our study shows that the finding for ICRP age category year was similar to the NACG 2010 value. The determined local DRL values for the radiation doses associated with WB 18 F FDG PET/CT examinations are differed considerably between the ARPANSA and ICRP age category and EG weight category. Although, the determined 18 F-FDG value for ICRP 1 year is in good agreement with available publish data, it is preferable to optimise the 18 F-FDG administered activity while preserving the diagnostic image quality. The local DRL value determined from WB 18 F-FDG PET/CT examinations may help to establish the ARPANSA NDRL for WB FDG 18 F-PET/CT examinations.
Publisher: Wiley
Date: 03-01-2017
Abstract: To investigate how breast screen readers classify normal screening cases using descriptors of normal mammographic features and to assess test cases for suitability for a single reading strategy. Fifteen breast screen readers interpreted a test set of 29 normal screening cases and classified them by firstly rating their perceived difficulty to reach a 'normal' decision, secondly identifying the cases' salient normal mammographic features and thirdly assessing the cases' suitability for a single reading strategy. The relationship between the perceived difficulty in making 'normal' decisions and the normal mammographic features was investigated. Regular ductal pattern (T The findings suggest that perceived mammographic breast density has a major influence on the difficulty for readers to classify cases as normal and hence their suitability for single reading.
Publisher: Springer Science and Business Media LLC
Date: 07-06-2018
DOI: 10.1038/S41598-018-26100-5
Abstract: Radiologists can detect abnormality in mammograms at above-chance levels after a momentary glimpse of an image. The study investigated this instantaneous perception of an abnormality, known as a “gist” response, when 23 radiologists viewed prior mammograms of women that were reported as normal, but later diagnosed with breast cancer at subsequent screening. Five categories of cases were included: current cancer-containing mammograms, current mammograms of the normal breast contralateral to the cancer, prior mammograms of normal cases, prior mammograms with visible cancer signs in a breast from women who were initially reported as normal, but later diagnosed with breast cancer at subsequent screening in the same breast, and prior mammograms without any visible cancer signs from women labelled as initially normal but subsequently diagnosed with cancer. Our findings suggest that readers can distinguish patients who were diagnosed with cancer, from in iduals without breast cancer (normal category), at above-chance levels based on a half-second glimpse of the mammogram even before any lesion becomes visible on the mammogram. Although 20 of the 23 radiologists demonstrated this ability, radiologists’ abilities for perceiving the gist of the abnormal varied between the readers and appeared to be linked to expertise. These results could have implications for identifying women of higher than average risk of a future malignancy event, thus impacting upon tailored screening strategies.
Publisher: Wiley
Date: 04-04-2017
DOI: 10.1002/JMRS.230
Publisher: SPIE
Date: 04-03-2019
DOI: 10.1117/12.2513185
Publisher: British Institute of Radiology
Date: 06-2004
DOI: 10.1259/BJR/18928981
Abstract: Diagnostic efficacy is related to viewing conditions. An increasing number of radiology departments are using workstations for reporting and it was the aim of this study to assess monitor performance and ambient lighting in areas allocated to soft-copy reporting and review. The study was performed in 4 Dublin hospitals and 20 monitors were examined. Using a Society of Motion Pictures and Television Engineers' (SMPTE) test pattern, maximum luminance, spatial uniformity of luminance, temporal luminance stability, brightness and contrast resolution (gamma), geometry and ambient lighting was assessed. The results demonstrated that although temporal luminance stability and spatial uniformity appeared to be at acceptable levels, maximum luminance and gamma value variations were noted, with maximum luminance and geometry values often not complying with published guidelines. Cleaning the monitor face had no impact. 90% of viewing areas had acceptable ambient lighting levels. The data presented demonstrate that monitors examined were not operating at optimal levels for all performance parameters and inclusion of regular assessments of monitors should be part of an imaging department's ongoing quality assurance programme.
Publisher: Oxford University Press (OUP)
Date: 02-2004
DOI: 10.1093/RPD/NCH029
Publisher: Elsevier BV
Date: 2019
DOI: 10.1016/J.CRAD.2018.10.008
Abstract: To measure the level of radiologists' performance in lung cancer detection, and to explore radiologists' performance in cancer specialised and non-specialised centres. Thirty radiologists read 60 chest computed tomography (CT) examinations. Thirty cases had surgically or biopsy-proven lung cancer and 30 were cancer-free cases. The cancer cases were validated by four expert radiologists who located the malignant lung nodules. Reader performance was evaluated by calculating sensitivity, location sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve (AUC). In addition, sensitivity at fixed specificity (0.794) was computed from each reader's estimated ROC curve. The radiologists had a mean sensitivity of 0.749, sensitivity at fixed specificity of 0.744, location sensitivity of 0.666, specificity of 0.81 and AUC of 0.846. Radiologists in the specialised and non-specialised cancer centres had the following (specialised, non-specialised) pairs of values: sensitivity=(0.80, 0.719) sensitivity for fixed 0.794 specificity=(0.752, 0.740) location sensitivity=(0.712, 0.637) specificity=(0.794, 0.82) and AUC=(0.846, 0.846). The efficacy of radiologists was comparable to other studies. Furthermore, AUC outcomes were similar for specialised and non-specialised cancer centre radiologists, suggesting they have similar discriminatory ability and that the higher sensitivity and lower specificity for specialised-centre radiologists can be attributed to them being less conservative in interpreting case images.
Publisher: Elsevier BV
Date: 08-2009
Publisher: Elsevier BV
Date: 04-2008
DOI: 10.1016/J.ACRA.2007.12.005
Abstract: In recent years, there has been increasing interest in the impact of environmental factors such as ambient light on radiologist performance. One commonly encountered distractor found within all clinical departments that has received little or no attention is acoustic noise. The present work records the level of noises encountered within environments where radiologic images are viewed and establishes the impact of a clinically relevant level of noise on the ability of radiologists to perform a typical diagnostic task. Noise levels were recorded 10 times within each of 14 environments, 11 of which were locations where radiologic images are judged. Thirty chest images were then presented to 26 senior radiologists, who were asked to detect up to three nodular lesions within 30 posteroanterior chest x-ray images in the absence and presence of noise at an litude demonstrated in the clinical environment. Jackknife free-response receiver-operating characteristic analyses was performed on the free-response data. The results demonstrated that noise litudes rarely exceeded that encountered with normal conversation with the maximum mean value for an image-viewing environment being 56.1 dB. This level of noise had no impact on the ability of radiologists to identify chest lesions with figure of merits of 0.68, 0.69, and 0.68 with noise and 0.65, 0.68, and 0.67 without noise for chest radiologists, nonchest radiologists, and all radiologists, respectively. Equally, no differences were seen for false-positive and false-negative scores or on the time required to judge the images. These findings suggest that noise at levels encountered within areas where radiologic images are viewed is not a major distractor within the reporting environment, but the need for further work has been identified.
Publisher: American Roentgen Ray Society
Date: 12-2011
DOI: 10.2214/AJR.10.5859
Publisher: SPIE
Date: 22-05-2020
DOI: 10.1117/12.2563572
Publisher: Springer Science and Business Media LLC
Date: 30-05-2018
DOI: 10.1007/S00330-018-5473-4
Abstract: To compare the efficacy of use of digital breast tomosynthesis (DBT) with standard digital mammography (DM) workup views in the breast cancer assessment clinic. The Tomosynthesis Assessment Clinic trial (TACT), conducted between 16 October 2014 and 19 April 2016, is an ethics-approved, monocenter, multireader, multicase split-plot reading study. After written informed consent was obtained, 144 females (age > 40 years) who were recalled to the assessment clinic were recruited into TACT. These cases (48 cancers) were randomly allocated for blinded review of (1) DM workup and (2) DBT, both in conjunction with previous DM from the screening examination. Fifteen radiologists of varying experience levels in the Australia BreastScreen Program were included in this study, wherein each radiologist read 48 cases (16 cancers) in 3 non-overlapping blocks. Diagnostic accuracy was measured by means of sensitivity, specificity, and positive (PPV) and negative predictive values (NPV). The receiver-operating characteristic area under the curve (AUC) was calculated to determine radiologists' performances. Use of DBT (AUC = 0.927) led to improved performance of the radiologists (z = 2.62, p = 0.008) compared with mammography workup (AUC = 0.872). Similarly, the sensitivity, specificity, PPV, and NPV of DBT (0.93, 0.75, 0.64, 0.96) were higher than those of the workup (0.90, 0.56, 0.49, 0.92). Most radiologists (80%) performed better with DBT than standard workup. Cancerous lesions on DBT appeared more severe (U = 33,172, p = 0.02) and conspicuous (U = 24,207, p = 0.02). There was a significant reduction in the need for additional views (χ DBT has the potential to increase diagnostic accuracy and simplify the assessment process in the breast cancer assessment clinic. • Use of DBT in the assessment clinic results in increased diagnostic accuracy. • Use of DBT in the assessment clinic improves performance of radiologists and also increases the confidence in their decisions. • DBT may reduce the need for additional views, ultrasound imaging, and biopsy.
Publisher: SPIE
Date: 20-02-2012
DOI: 10.1117/12.913754
Publisher: Springer Science and Business Media LLC
Date: 06-09-2014
DOI: 10.1007/S00330-014-3409-1
Abstract: The objectives are To to compare the diagnostic performance of combined digital breast tomosynthesis (DBT) and digital mammography (DM) with that of DM alone, as a function of radiologists' experience with DBT. Ethical committee approval was obtained. Fifty cases (27 cancer, 23 normal), each containing both digital mammography (DM) and digital breast tomosynthesis (DBT) images, were reviewed by 26 radiologists, ided into three groups according to level of experience with DBT (none, workshop experience, and clinical experience). The radiologists' diagnostic performance using DM was compared with that using DM + DBT, and evaluated by area under receiver-operating characteristic curve (AUC), jackknife free-response receiver-operator characteristics figure of metric (JAFROC FOM), sensitivity, location sensitivity, and specificity. For all readers combined, performance using DM + DBT was significantly higher than for DM alone by both AUC (0.788 vs 0.681, p < 0.001) and JAFROC FOM (0.745 vs 0.621, p < 0.001). Similar results were obtained for readers with no DBT experience (AUC 0.775 vs 0.682, p = 0.004 JAFROC FOM 0.695 vs 0.603, p = 0.016) and with clinical DBT experience (AUC 0.789 vs 0.681, p = 0.042 and JAFROC FOM 0.764 vs 0.632, p = 0.031). Addition of DBT to DM significantly improves radiologists' diagnostic performance whether or not they have prior DBT experience. • Adding DBT to DM increased the number of detected cancers • DBT + DM led to more accurate localization of breast cancers than DM • Addition of DBT improved radiologists' performance regardless of prior DBT experience • High-volume radiologists with different DBT experience levels performed similarly on DM + DBT.
Publisher: SPIE
Date: 23-02-2012
DOI: 10.1117/12.911577
Publisher: SPIE
Date: 16-04-0004
DOI: 10.1117/12.2205391
Publisher: SPIE
Date: 02-03-2006
DOI: 10.1117/12.660137
Publisher: SPIE
Date: 06-03-2008
DOI: 10.1117/12.770305
Publisher: Oxford University Press (OUP)
Date: 17-06-2006
DOI: 10.1093/RPD/NCL076
Abstract: The current work investigates the most effective type osition of aprons for postero-anterior (PA) and lateral projections of the chest. Two apron-types were investigated: 'Mavig' half apron and Amray light plus' wrap-around apron. The half apron was positioned at the X-ray tube or image receptor side of an anthropomorphic phantom for PA and lateral projections. Radiation dose at positions corresponding to ovaries, uterus and testes was measured with thermoluminescent dosemeters. The wrap-around apron offers a higher level of protection for PA and lateral projections compared with the half apron, regardless of where the latter was positioned, with dose reductions of up to 88% compared with no apron. For the PA position, the half apron should be positioned in a gender-specific way, facing the X-ray tube for females and the image receptor for males. With all apron types ositions, gonadal dose is still clearly evident, from internal scatter, emphasising the importance of other protective practices such as collimation.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2013
Publisher: Springer Science and Business Media LLC
Date: 26-04-2012
Publisher: Elsevier BV
Date: 12-2019
DOI: 10.1016/J.ACRA.2018.12.017
Abstract: Breast Screen Reader Assessment Strategy (BREAST) is an innovative training and research program for radiologists in Australia and New Zealand. The aim of this study is to evaluate the efficacy of BREAST test sets in improving readers' performance in detecting cancers on mammograms. Between 2011 and 2018, 50 radiologists (40 fellows, 10 registrars) completed three BREAST test sets and 17 radiologists completed four test sets. Each test set contained 20 biopsy-proven cancer and 40 normal cases. Immediate image-based feedback was available to readers after they completed each test set which allowed the comparison of their selections with the truth. Case specificity, case sensitivity, lesion sensitivity, the Receiver Operating Characteristic (ROC) Area Under the Curve (AUC) and Jackknife Free-Response Receiver Operating Characteristic (JAFROC) Figure of Merit (FOM) were calculated for each reader. Kruskal-Wallis test was utilized to compare scores of the radiologist and registrars across all test-sets whilst Wilcoxon signed rank test was to compare the scores between pairs of test sets. Significant improvements in lesion sensitivity ranging from 21% to 31% were found in radiologists completing later test sets compared to first test set (p ≤ 0.01). Eighty three percent of radiologists achieved higher performance in lesion sensitivity after they completed the first read. Registrars had significantly better scores in the third test set compared to the first set with mean increases of 79% in lesion sensitivity (p = 0.005) and 37% in JAFROC (p = 0.02). Sixty percent and 100% of registrars increased their scores in lesion sensitivity in the second and third reads compared to the first read while the percentage of registrars with higher scores in JAFROC was 80%. Introduction of BREAST into national training programs appears to have an important impact in promoting diagnostic efficacy amongst radiologists and radiology registrars undergoing mammographic readings.
Publisher: Wiley
Date: 10-11-2019
DOI: 10.1002/JMRS.369
Publisher: Springer International Publishing
Date: 2016
Publisher: Elsevier BV
Date: 08-2005
Publisher: Springer International Publishing
Date: 2016
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.EJMP.2015.10.092
Abstract: In the course of performance acceptance testing, benchmarking or quality control of X-ray imaging systems, it is sometimes necessary to harden the X-ray beam spectrum. IEC 61267 specifies materials and methods to accomplish beam hardening and, unfortunately, requires the use of 99.9% pure aluminium (Alloy 1190) for the RQA beam quality, which is expensive and difficult to obtain. Less expensive and more readily available filters, such as Alloy 1100 (99.0% pure) aluminium and copper/aluminium combinations, have been used clinically to produce RQA series without rigorous scientific investigation to support their use. In this paper, simulation and experimental methods are developed to determine the differences in beam quality using Alloy 1190 and Alloy 1100. Additional simulation investigated copper/aluminium combinations to produce RQA5 and outputs from this simulation are verified with laboratory tests using different filter s les. The results of the study demonstrate that although Alloy 1100 produces a harder beam spectrum compared to Alloy 1190, it is a reasonable substitute. A combination filter of 0.5 mm copper and 2 mm aluminium produced a spectrum closer to that of Alloy 1190 than Alloy 1100 with the added benefits of lower exposures and lower batch variability.
Publisher: EpiSmart Science Vector Ltd
Date: 03-2019
Publisher: Wiley
Date: 21-09-2013
DOI: 10.1111/J.1754-9485.2012.02447.X
Abstract: Multidetector computed tomographic angiography is becoming the modality of choice for evaluation of the supra-aortic circulation in acute stroke imaging. Variations of the supra-aortic circulation, in particular of the extracranial arteries, are common. This article aims to provide a pictorial description of the variant anatomy of the aortic arch and extracranial arteries. Knowledge of the presence and clinical relevance of normal variants such as anomalies, duplications and embryological persistence plays a clinically relevant role in the diagnosis and management of neurological and surgical conditions, particularly as we enter an era of increasing extracranial intervention.
Publisher: Oxford University Press (OUP)
Date: 11-03-2010
DOI: 10.1093/RPD/NCQ094
Abstract: The advent of digital radiography poses the risk of unnoticed increases in patient dose. Manufacturers have responded to this by offering an exposure index (EI) value to the clinician. Whilst the EI value is a measure of the air kerma at the detector surface, it has been recommended by international agencies as a method of monitoring radiation dose to the patient. Recent studies by the group have shown that EI values are being used in clinical practice to monitor radiation dose and assess image quality. This study aims to compare the clinical consistency of the EI value in computed radiography (CR) and direct digital radiography (DR) systems. An anthropormorphic phantom was used to simulate four common radiographic examinations: skull, pelvis, chest and hand. These examinations were chosen as they provide contrasting exposure parameters, image detail and radiation dose measurements. Four manufacturers were used for comparison: Agfa Gaevert CR, Carestream CR, Philips Digital Diagnost DR and Siemens DR. For each examination, the phantom was placed in the optimal position and exposure parameters were chosen in accordance with European guidelines and clinical practice. Multiple exposures were taken and the EI recorded. All exposure parameters and clinical conditions remained constant throughout. For both DR systems, the EI values remained consistent throughout. No significant change was noted in any examination. In both CR systems, there were noteworthy fluctuations in the EI values for all examinations. The largest for the Agfa system was a variation of 1.88-2.21 for the skull examination. This represents to the clinician a doubling of detector dose, despite all exposure parameters remaining constant. In the Kodak system, the largest fluctuation was seen for the chest examination where the EI ranged from 2560 to 2660, representing approximately an increase of 30 % in radiation dose, despite consistent parameters. The fluctuations seen with the CR systems are most likely due to image processing delay, replacing of the imaging plate and calibration factors. Fluctuations in EI values may result in confusion to the clinician and unnecessary repeat examinations. The reliability of EI values as a feedback mechanism for CR is also questionable.
Publisher: British Institute of Radiology
Date: 11-2018
DOI: 10.1259/BJR.20180071
Publisher: SPIE
Date: 07-03-2018
DOI: 10.1117/12.2293364
Publisher: Elsevier BV
Date: 08-2019
Abstract: To compare breast screening attendances of Indigenous and non-Indigenous women. A total of 4,093 BreastScreen cases were used including 857 self-identified Indigenous women. Chi-squared analysis compared data between Indigenous and non-Indigenous women. Logistic regression was used for groupings based on visits-to-screening frequency. Odds ratios and 95% confidence intervals were calculated for associations with low attendance. Indigenous women were younger and had fewer visits to screening compared with non-Indigenous women. Non-English speaking was mainly associated with fewer visits for Indigenous women only (OR 1.9, 95%CI 1.3-2.9). Living remotely was associated with fewer visits for non-Indigenous women only (OR 1.3, 95%CI 1.1-1.5). Shared predictors were younger age (OR 12.3, 95%CI 8.1-18.8 and OR 11.5, 95%CI 9.6-13.7, respectively) and having no family history of breast cancer (OR 2.1, 95%CI 1.3-3.3 and OR 1.8, 95%CI 1.5-2.1, respectively). Factors associated with fewer visits to screening were similar for both groups of women, except for language which was significant only for Indigenous women, and remoteness which was significant only for non-Indigenous women. Implications for public health: Health communication in Indigenous languages may be key in encouraging participation and retaining Indigenous women in BreastScreen improving access for remote-living non-Indigenous women should also be addressed.
Publisher: Wiley
Date: 20-11-2013
DOI: 10.1002/JMRS.25
Publisher: SPIE
Date: 07-03-2018
DOI: 10.1117/12.2293366
Publisher: SPIE
Date: 11-03-2014
DOI: 10.1117/12.2044370
Publisher: Elsevier BV
Date: 04-2014
DOI: 10.1016/J.CRAD.2013.11.014
Abstract: Effective detection of breast cancer using mammography is an important public health issue worldwide. Breasts that contain higher levels of fibroglandular compared with fatty tissue increase breast radio-opacity making it more difficult to differentiate between normal and abnormal findings. The higher prevalence of breast cancer amongst women with denser breasts demands the origination of effective solutions to manage this common radiographic appearance. This brief review considers the impact of higher levels of density on cancer detection and the importance of digital technology in possibly reducing the negative effects of increased density.
Publisher: Springer Science and Business Media LLC
Date: 15-01-2013
Publisher: SPIE
Date: 04-03-2019
DOI: 10.1117/12.2512755
Publisher: Elsevier BV
Date: 04-2014
DOI: 10.1016/J.CRAD.2013.11.010
Abstract: To examine how the location where reading takes place and the availability of prior images can affect performance in breast test-set reading. Under optimized viewing conditions, 10 expert screen readers each interpreted a reader-specific set of images containing 200 mammographic cases. Readers, randomly ided into two groups read images under one of two pairs of conditions: clinical read with prior images and laboratory read with prior images laboratory read with prior images and laboratory read without prior images. Region-of-interest (ROI) figure-of-merit (FOM) was analysed using JAFROC software. Breast side-specific sensitivity and specificity were tested using Wilcoxon matched-pairs signed rank tests. Agreement between pairs of readings was measured using Kendall's coefficient of concordance. Group performances between test-set readings demonstrated similar ROI FOMs, sensitivity and specificity median values, and acceptable levels of agreement between pairs of readings were shown (W = 0.75-0.79, p < 0.001) for both pairs of reading conditions. On an in idual reader level, two readers demonstrated significant decreases (p < 0.05) in ROI FOMs when prior images were unavailable. Reading location had an inconsistent impact on in idual performance. Reading location and availability of prior images did not significantly alter group performance.
Publisher: Elsevier BV
Date: 06-2018
DOI: 10.1016/J.ARTMED.2018.04.005
Abstract: Identifying carcinoma subtype can help to select appropriate treatment options and determining the subtype of benign lesions can be beneficial to estimate the patients' risk of developing cancer in the future. Pathologists' assessment of lesion subtypes is considered as the gold standard, however, sometimes strong disagreements among pathologists for distinction among lesion subtypes have been previously reported in the literature. To propose a framework for classifying hematoxylin-eosin stained breast digital slides either as benign or cancer, and then categorizing cancer and benign cases into four different subtypes each. We used data from a publicly available database (BreakHis) of 81 patients where each patient had images at four magnification factors (×40, ×100, ×200, and ×400) available, for a total of 7786 images. The proposed framework, called MuDeRN (MUlti-category classification of breast histopathological image using DEep Residual Networks) consisted of two stages. In the first stage, for each magnification factor, a deep residual network (ResNet) with 152 layers has been trained for classifying patches from the images as benign or malignant. In the next stage, the images classified as malignant were sub ided into four cancer subcategories and those categorized as benign were classified into four subtypes. Finally, the diagnosis for each patient was made by combining outputs of ResNets' processed images in different magnification factors using a meta-decision tree. For the malignant/benign classification of images, MuDeRN's first stage achieved correct classification rates (CCR) of 98.52%, 97.90%, 98.33%, and 97.66% in ×40, ×100, ×200, and ×400 magnification factors respectively. For eight-class categorization of images based on the output of MuDeRN's both stages, CCRs in four magnification factors were 95.40%, 94.90%, 95.70%, and 94.60%. Finally, for making patient-level diagnosis, MuDeRN achieved a CCR of 96.25% for eight-class categorization. MuDeRN can be helpful in the categorization of breast lesions.
Publisher: Springer Science and Business Media LLC
Date: 04-02-2019
Publisher: American Roentgen Ray Society
Date: 07-2010
DOI: 10.2214/AJR.09.2851
Publisher: SPIE
Date: 10-03-2017
DOI: 10.1117/12.2254177
Publisher: Informa UK Limited
Date: 2017
DOI: 10.2147/BCTT.S125584
Publisher: Springer Science and Business Media LLC
Date: 02-04-2019
DOI: 10.1007/S00038-019-01237-W
Abstract: To compare the mammographic densities and other characteristics of Aboriginal and non-Aboriginal women screened in Australia. Population screening programme data of Aboriginal (n = 857) and non-Aboriginal women (n = 3236) were used. Mann-Whitney U test compared ages at screening and Chi-square tests compared personal and clinical information. Logistic regression analysis was used for density groupings. OR and 95% CI were calculated for multivariate association for density. Mammographic density was lower amongst Aboriginal women (P < 0.001). For non-Aboriginal women, higher density was associated with younger age (OR 2.4, 95% CI 2.1-2.8), recall to assessment (OR 2.2, 95% CI 1.6-3.0), family history of breast cancer (OR 1.4, 95% CI 1.2-1.6), English-speaking background (OR 1.4, 95% CI 1.2-1.6), and residence in remote areas (OR 1.2, 95% CI 1.1-1.4). For Aboriginal women, density was associated with younger age (OR 2.7, 95% CI 2.0-3.5 P < 0.001), and recall to assessment (OR 2.3, 95% CI 1.4-3.9 P < 0.05). Significant differences between Aboriginal and non-Aboriginal women were found. There were more significant associations for dense breasts for non-Aboriginal women than for Aboriginal women.
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.CRAD.2017.03.025
Abstract: To investigate the dose-length product (DLP) during intracranial computed tomography angiography (CTA) using a patient-specific contrast formula. Intracranial CTA was performed on 120 patients using 64-channel CT. Patients were subjected in equal numbers to one of two acquisitions/contrast medium protocols. Protocol A, consisted of 80 ml contrast medium and protocol B, involved a novel contrast medium formula. In each protocol, contrast medium and saline were injected at a flow rate of 4.5 ml/s. The DLP and contrast volume (CV) were measured between each protocol and the data obtained were compared using two-tailed independent t-test. Mean arterial vessel attenuation was up to 56% (p<0.01) higher using protocol B compared with A. In the venous system, the mean vessel attenuation was significantly lower in protocol B than A with a maximum reduction of 93% (p<0.001). The mean CV was significantly lower in protocol B (53±10 ml) compared to A (80±1 ml, p<0.001). The scan time was equal in each protocol (B, 4.22±1.2 seconds A, 4.01±1.3 seconds). A significant reduction in mean DLP was demonstrated in protocol B (3.99±0.22 mSv) compared to A (4.74±0.22 mSv p=0.02). A significant reduction in CV and DLP during intracranial CTA can be achieved when employing a patient-specific contrast medium formula.
Publisher: SPIE
Date: 03-2017
DOI: 10.1117/12.2254605
Publisher: SPIE
Date: 23-02-2012
DOI: 10.1117/12.912082
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2018
Publisher: SPIE
Date: 28-03-2013
DOI: 10.1117/12.2007451
Publisher: Wiley
Date: 10-2018
DOI: 10.1002/MP.13161
Abstract: To propose a framework for optimal pairing of radiologists when reading mammograms based on their search patterns. Four experienced and four less-experienced radiologists were asked to assess 120 cases (59 with cancers) while their eye positions were tracked. Fourteen eye-tracking metrics were extracted to quantify the differences among radiologists' visual search pattern. For each radiologist and metric, less-experienced radiologists and expert readers were ranked based on the level of similarities in gaze patterns (from the most different to the most similar). Less-experienced readers and experts were also ranked based on the values of area under the receiver operating characteristic curve (AUC) after pairing (the best possible way of ranking). Using the Kendall's tau distance, rankings based on different metrics were compared with the best possible ranking. Using paired Wilcoxon signed-rank test, the AUC values when pairing in the best way were compared with pairing based on different metrics. Finally, we investigated the robustness of pairing strategies against the small s le size. For ranking the experienced radiologists, results from eight metrics were as good as the best possible ranking. For the less-experienced ones, only one metric resulted in a ranking comparable to the best possible way of ranking. The AUC values of pairings based on these metrics did not differ significantly from the best pairing scenario. Compared to the pairings based on the cognitive metrics, the ranking based on AUC values varied more greatly with the s le size, suggesting that it is less robust against the small s le size compared to the cognitive metrics. Different pairings may have different effects on performance some are detrimental while some improve the performance of the pair. Using the suggested cognitive metrics, we can optimize the pairings even with a small dataset.
Publisher: The Sax Institute
Date: 2019
DOI: 10.17061/PHRP2921911
Abstract: There are currently no single disruptors to breast cancer screening akin to the impact of human papillomavirus testing and vaccination on cervical cancer screening. However, there is a groundswell of interest to review the BreastScreen Australia program to consider more risk-based screening protocols and to establish whether to routinely inform women about their breast density. We propose a framework for a considered, evidence-based review. Population-level effectiveness of breast cancer screening is ultimately measured through its impact on breast cancer mortality, and this has been realised in Australia. Effectiveness can also be measured through treatment intensity, estimated overdiagnosis, false-positive screens and health economics measures. Key levers to improve such population-level outcomes include screening participation, screening test sensitivity and specificity, risk assessment and screening protocols. We propose that the review of the program should fall under an evidence-based, consensus-guided framework comprising four complementary elements: improved evidence on current program performance for population risk subgroups regularly updated evidence on key levers for change clinical trials and population simulation modelling working in tandem and consensus-based decision making about the degree of improvement required to justify change. Informing women about their breast density is feasible and would be valued by some BreastScreen clients to help understand the accuracy of their screening test. However, without agreed protocols for screening women with dense breasts, increases in supplemental screening as observed in other settings would, in Australia, shift screening costs to clients and Medicare. This would reduce equity of access to population screening, and maintaining BreastScreen's usual standard of monitoring and quality management (such as screen-detected and interval cancer diagnoses, and imaging and biopsy rates) would require data linkage between BreastScreen and other services. The proposed framework assesses screening effectiveness in the era of personalised medicine, allows review of multiple factors that may together warrant change, and gives full, evidence-based consideration of the benefits, harms and costs of various approaches to breast cancer screening. To be effective, the framework requires a coordinated approach to generating the evidence required for policy makers, with time to prepare appropriate health services.
Publisher: Oxford University Press (OUP)
Date: 22-12-2017
DOI: 10.1093/RPD/NCX294
Abstract: This study examines the kerma-area product (PKA) levels from paediatric cardiac catheterisations at a major Children's Hospital over three different time periods in order to gain an understanding of the causation of dose variations over time and to present a model for dose reduction. A retrospective review of 1245 paediatric procedural records was undertaken. This cohort consisted of patients that were catheterised over a period from November 2007 to July 2009, October 2009 to November 2011 and January 2016 to December 2016. The age distribution was from newborn to 18 years. Archived (PKA) readings were retrieved and analysed. The 75th percentile PKA values for the specific age categories over time periods (1, 2, 3) were 0-30 days-(5.47, 1.37, 1.37) Gy cm2 1-12 months-(6.42, 2.03, 1.06) Gy cm2 1-3 years-(11.25, 3.20, 1.25) Gy cm2 3-5 years-(12.65, 3.72, 2.88) Gy cm2 5-10 years-(12.80, 8.53, 3.52) Gy cm2 10-15 years-(27.92, 10.85, 2.97) Gy cm2 >15 years-(29.09, 27.81, 11.65) Gy cm2. Using newer imaging technologies, optimising dose reduction strategies and regular dose auditing can transform radiation dose delivery for paediatric x-ray examinations. Our centre provides a template for dose reduction success worldwide.
Publisher: SPIE
Date: 28-03-2013
DOI: 10.1117/12.2007697
Publisher: SPIE
Date: 04-03-2010
DOI: 10.1117/12.844478
Publisher: SPIE
Date: 10-03-2017
DOI: 10.1117/12.2253993
Publisher: SPIE
Date: 17-03-2015
DOI: 10.1117/12.2083152
Publisher: Springer International Publishing
Date: 2016
Publisher: Radiological Society of North America (RSNA)
Date: 10-2011
Publisher: Radiological Society of North America (RSNA)
Date: 05-2016
DOI: 10.1148/RADIOL.2015150511
Abstract: To investigate opacification of head and neck vasculature during computed tomography (CT) of supraclavicular lymph nodes with a quadruple-phase contrast media and saline dual-injection protocol. This retrospective study was institutional review board approved. In 180 consecutive patients, routine head and neck CT was performed with one of two protocols: protocol A, craniocaudal scan direction with 100 mL of contrast material injected intravenously as a single bolus or protocol B, 100 mL of contrast material injected in four phases (phases 1-2, 60 mL of contrast material and saline injected at 2.5 mL/sec phases 3-4, 40 mL of contrast material and saline injected at 2.5 mL/sec) both protocols had a fixed scan delay of 70 seconds. Attenuation of supraclavicular arteries and veins was measured with arteriovenous contrast ratio (AVCR) and contrast-to-noise ratio (CNR). Effective dose was calculated. Data were compared with the two-s le t test. Receiver operating characteristic (ROC) and visual grading characteristic analyses were performed. Arterial attenuation was up to 20% higher (P < .05) after protocol B (mean ± standard deviation, 234.5 HU ± 33.2) than protocol A (160.0 HU ± 29.5). Venous system attenuation was significantly lower in protocol B (164.0 HU ± 17.0) than in protocol A (664.0 HU ± 12.0), with up to a 75% reduction (P < .0001). Protocol B generated significant (P < .0001) improvements in AVCR at multiple anatomic sites. At all anatomic levels, mean CNR with protocol B (34.4 HU ± 9.0) was significantly higher than that with protocol A (14.5 HU ± 14.0) (P < .0313). Effective dose was significantly reduced with protocol B (2.6 mSv ± 0.4 vs 3.2 mSv ± 0.8 with protocol A P < .0041). ROC analysis demonstrated significantly higher area under the ROC curve for protocol B (P < .0022), with interreader agreement increasing from poor to excellent in lymph node visualization. Significant improvement in lymph node visualization at the cervicothoracic junction is achieved with a quadruple-phase contrast media injection protocol.
Publisher: British Institute of Radiology
Date: 07-2009
DOI: 10.1259/BJR/42223683
Abstract: Rheumatoid arthritis (RA) is the most common form of inflammatory disease, affecting 1-2% of the population. Posteroanterior (PA) and Brewerton projections are well established in radiographic practice for scoring and monitoring RA, but there is little evidence to demonstrate the diagnostic efficacy of these techniques. This work, by varying the positioning of a cadaveric hand, investigates whether an alternative radiographic projection could yield greater diagnostic information than the traditional techniques. Phase I of the study evaluated moving the hand 15 degrees from the anteroposterior position and then in 5 degrees increments in four directions: medial rotation, lateral rotation, flexion of the wrist and extension of the wrist. Phase II of the study took the optimum projections from Phase I and further manipulated these positions in a direction at right angles to the original position. Images were scored based on joint space visualisation in 29 joints. Results demonstrated that significantly higher diagnostic efficacy was evident with 15 degrees lateral rotation of the hand or 15 degrees flexion at the wrist compared to the Brewerton projection. Either projection is recommended, but on the basis of patient comfort, the latter of these novel positions, now known as the UCD projection, was chosen as the optimum procedure to replace the Brewerton projection. The value of using cadavers for the establishment of optimum radiographic procedures is highlighted.
Publisher: Wiley
Date: 20-10-2019
DOI: 10.1002/MP.13842
Abstract: Propagation-based phase-contrast computed tomography (PB-CT) is a method for three-dimensional x-ray imaging that utilizes refraction, as well as absorption, of x rays in the tissues to increase the signal-to-noise ratio (SNR) in the resultant images, in comparison with equivalent conventional absorption-only x-ray tomography (CT). Importantly, the higher SNR is achieved without sacrificing spatial resolution or increasing the radiation dose delivered to the imaged tissues. The present work has been carried out in the context of the current development of a breast CT imaging facility at the Australian Synchrotron. Seven unfixed complete mastectomy s les with and without breast cancer lesions have been imaged using absorption-only CT and PB-CT techniques under controlled experimental conditions. The radiation doses delivered to the mastectomy s les during the scans were comparable to those approved for mammographic screening. Physical characteristics of the reconstructed images, such as spatial resolution and SNR, have been measured and compared with the results of the radiological quality assessment of the complete absorption CT and PB-CT image stacks. Despite the presence of some image artefacts, the PB-CT images have outperformed comparable absorption CT images collected at the same radiation dose, in terms of both the measured objective image characteristics and the radiological image scores. The outcomes of these experiments are shown to be consistent with predictions of the theory of PB-CT imaging and previous reported experimental studies of this imaging modality. The results presented in this paper demonstrate that PB-CT holds a high potential for improving on the quality and diagnostic value of images obtained using existing medical x-ray technologies, such as mammography and digital breast tomosynthesis (DBT). If implemented at suitable synchrotron imaging facilities, PB-CT can be used to complement existing imaging modalities, leading to more accurate breast cancer diagnosis.
Publisher: Elsevier BV
Date: 2016
DOI: 10.1016/J.ACRA.2015.09.011
Abstract: To investigate agreement on mammographic breast density (MD) assessment between automated volumetric software and Breast Imaging Reporting and Data System (BIRADS) categorization by expert radiologists. Forty cases of left craniocaudal and mediolateral oblique mammograms from 20 women were used. All images had their volumetric density classified using Volpara density grade (VDG) and average volumetric breast density percentage. The same images were then classified into BIRADS categories (I-IV) by 20 American Board of Radiology examiners. The results demonstrated a moderate agreement (κ = 0.537 95% CI = 0.234-0.699) between VDG classification and radiologists' BIRADS density assessment. Interreader agreement using BIRADS also demonstrated moderate agreement (κ = 0.565 95% CI = 0.519-0.610) ranging from 0.328 to 0.669. Radiologists' average BIRADS was lower than average VDG scores by 0.33, with their mean being 2.13, whereas the mean VDG was 2.48 (U = -3.742 P < 0.001). VDG and BIRADS showed a very strong positive correlation (ρ = 0.91 P < 0.001) as did BIRADS and average volumetric breast density percentage (ρ = 0.94 P < 0.001). Automated volumetric breast density assessment shows moderate agreement and very strong correlation with BIRADS interreader variations still exist within BIRADS. Because of the increasing importance of MD measurement in clinical management of patients, widely accepted, reproducible, and accurate measures of MD are required.
Publisher: Elsevier BV
Date: 10-2020
Publisher: Wiley
Date: 11-05-2014
DOI: 10.1002/JMRS.49
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2017
Publisher: Springer Science and Business Media LLC
Date: 23-01-2020
DOI: 10.1007/S00330-019-06567-0
Abstract: To evaluate and compare the image quality of propagation-based phase-contrast computed tomography (PB-CT) using synchrotron radiation and conventional cone-beam breast computed tomography (CBBCT) based on various radiological image quality criteria. Eight excised breast tissue s les of various sizes and containing different lesion types were scanned using PB-CT at a synchrotron facility and using CBBCT at a university-affiliated breast imaging centre. PB-CT scans were performed at two different mean glandular dose (MGD) levels: standard (5.8 mGy) and low (1.5 mGy), for comparison with CBBCT scans at the standard MGD (5.8 mGy). Image quality assessment was carried out using six quality criteria and six independent medical imaging experts in a reading room with mammography workstations. The interobserver agreement between readers was evaluated using intraclass correlation coefficient (ICC), and image quality was compared between the two breast imaging modalities using the area under the visual grading characteristic curve (AUC Interobserver agreement between the readers showed moderate reliability for five image criteria (ICC: ranging from 0.488 to 0.633) and low reliability for one criterion (image noise) (ICC 0.307). For five image quality criteria (overall quality, perceptible contrast, lesion sharpness, normal tissue interfaces, and calcification visibility), both standard-dose PB-CT images (AUC Synchrotron-based PB-CT can achieve a significantly higher radiological image quality at a substantially lower radiation dose compared with conventional CBBCT. • PB-CT using synchrotron radiation results in higher image quality than conventional CBBCT for breast imaging. • PB-CT using synchrotron radiation requires a lower radiation dose than conventional CBBCT for breast imaging. • PB-CT can help clinicians diagnose patients with breast cancer.
Publisher: Wiley
Date: 26-11-2009
DOI: 10.1111/J.1754-9485.2009.02119.X
Abstract: Reader variability is a problem in mammography image reporting and compromises the efficacy of screening programmes. The purpose of this exploratory study was to survey reader practice in reporting screening mammograms in Australia to identify aspects of practice that warrant further investigation. Mammography reporting practice and influences on concentration and attention were investigated by using an original questionnaire distributed to screen readers in Australia. A response rate of 71% (83 out of 117) was achieved. Demographic data indicated that the majority of readers were over 46 years of age (73%), have been reporting on screening mammograms for over 10 years (61%), take less than 1 min to report upon a screening mammogram examination (66%), report up to 200 examinations in a single session (83%) and take up to 2 h to report one session (61%). A majority report on more than 5000 examinations annually (66%) 93% of participants regard their search strategy as systematic, 87% agreed that their concentration can vary throughout a session, 64% agreed that the relatively low number of positives can lead to lapses in concentration and attention and almost all (94%) participants agreed that methods to maximise concentration should be explored. Participants identified a range of influences on concentration within their working environment including volume of images reported in one session, image types and aspects of the physical environment. This study has provided important evidence of the need to investigate adverse influences on concentration during mammography screen reporting.
Publisher: Elsevier BV
Date: 11-2008
Publisher: Informa UK Limited
Date: 2011
DOI: 10.3109/01443615.2010.522266
Abstract: Abnormal placental grading is associated with poor pregnancy outcome. The aim of this study was to measure intra- and interobserver variability in placental grading. Five expert sonographers independently graded 90 images on two occasions, each viewing separated by 1 week. A number of measures were employed to standardise assessment and minimise potential for variation: prior agreement was established between observers on the classifications for placental grading a controlled viewing laboratory was used for all viewings ambient lighting was optimal and monitors were calibrated to the GSDF standard. Kappa (κ) analysis was used to measure observer agreement. Substantial variations between in iduals' scores were observed. A mean κ-value of 0.34 (range from 0.19 to 0.50) indicated fair interobserver agreement over the two occasions and only nine of the 90 images were graded the same by all five observers. Intraobserver agreement had a moderate mean κ-value of 0.52, with in idual comparisons ranging from 0.45 to 0.66. This study demonstrates that, despite standardised viewing conditions, Grannum grading of the placenta is not a reliable technique even among expert observers. The need for new methods to assess placental health is required and work is ongoing to develop 2D and 3D software-based methods.
Publisher: Elsevier BV
Date: 05-2007
Publisher: Springer Science and Business Media LLC
Date: 11-08-2015
Publisher: Elsevier BV
Date: 06-2018
DOI: 10.1016/J.CLBC.2017.07.006
Abstract: Breast cancer is the most frequently diagnosed noncutaneous malignancy in women living in Gulf Cooperation Council countries. The present report aimed to highlight the similarities and variations in breast cancer incidence, age at diagnosis, clinicopathologic features, molecular characteristics, and lifestyle factors that contribute to an increasing incidence of breast cancer compared with neighboring Arab and westernized countries. The data presented, although having important implications for policy makers, also highlights the need for further research. Such research would ensure that effective prevention and detection strategies are tailored to the specific needs of the Gulf women such that the management of breast cancer is optimized.
Publisher: Springer Science and Business Media LLC
Date: 04-06-2013
DOI: 10.1007/S00330-013-2919-6
Abstract: To investigate pulmonary vasculature opacification during CTPA using an optimised patient-specific protocol for administering contrast agent. CTPA was performed on 200 patients with suspected PE. Patients were assigned to two protocol groups: protocol A, fixed 80 ml contrast agent protocol B used a patient-specific approach. The mean cross-sectional opacification profile of 8 central and 11 peripheral pulmonary arteries and veins was measured and the arteriovenous contrast ratio (AVCR) calculated. Protocols were compared using Mann-Whitney U non-parametric statistics. Jack-knife alternative free-response receiver-operating characteristic (JAFROC) analyses assessed diagnostic efficacy. Interobserver variations were investigated using kappa methods. A number of pulmonary arteries demonstrated increases in opacification (P < 0.03) for protocol B compared to A, whilst opacification in the heart and veins was reduced in protocol B (P = 0.05). Increased AVCR in protocol B compared with A was observed at all anatomic locations (P < 0.0002). Increased JAFROC (P < 0.0002) and kappa variation were observed with protocol B (κ = 0.78) compared to A (κ = 0.25). Mean contrast volume was reduced in protocol B (33 ± 9 ml) compared to A (80 ± 1 ml). Significant improvements in visualisation of the pulmonary vasculature can be achieved with a low volume of contrast agent using injection timing based on a patient-specific contrast formula. • Optimal opacification of the pulmonary arteries is essential for CT pulmonary angiography. • Matching timing with vessel dynamics significantly improves vessel opacification. • This leads to increased arterial opacification and reduced venous opacification. • This can also lead to a reduced volume of contrast agent.
Publisher: Public Library of Science (PLoS)
Date: 10-01-2019
Publisher: SPIE
Date: 23-02-2012
DOI: 10.1117/12.910452
Publisher: SPIE
Date: 22-03-2016
DOI: 10.1117/12.2216698
Publisher: Oxford University Press (OUP)
Date: 18-02-2008
DOI: 10.1093/RPD/NCN048
Abstract: This study has gathered data across Ireland to determine the range of radiation doses received during interventional cardiology (IC) investigations. Radiation doses for three common types of IC examinations where investigated: coronary angiography (CA), percutaneous coronary intervention (PCI) and pacemaker insertions (PPI). A total of 22 cardiac imaging suites participated in the study. Radiation dose was monitored for 1804 adult patients using dose area product (DAP) meters. In idual patient DAP values ranged from 136-23,101 cGy cm2, 475-41,038 cGy cm2 and 45-17,192 cGy cm2 for CA, PCI and PPI respectively, with third quartile values of 4654 cGy cm2, 10,650 cGy cm2 and 1686 cGy cm2. The importance of optimising radiation dose, while not compromising diagnostic efficacy is clear. Although setting reference levels for these complex procedures has some difficulties, it is important that some guideline values are available as a benchmark to guide the operators during these potentially high dose procedures. The third quartile values as described by this paper may offer such guidance.
Publisher: Elsevier BV
Date: 11-2013
Publisher: American Roentgen Ray Society
Date: 07-2018
DOI: 10.2214/AJR.17.19179
Publisher: Springer International Publishing
Date: 2016
Publisher: British Institute of Radiology
Date: 13-02-2018
DOI: 10.1259/BJR.20180032
Publisher: SPIE-Intl Soc Optical Eng
Date: 04-03-2015
Publisher: SPIE
Date: 26-02-2009
DOI: 10.1117/12.813505
Publisher: SAGE Publications
Date: 2020
Abstract: To document the mammographic breast density (MBD) distribution of Jordanian women and the relationship with MBD with age. Correlation between breast cancer diagnosis and density was also explored. A retrospective review of 660 screening mammograms from King Abdullah University Hospital was conducted. Mammograms were classified into 2 groups: normal (return to routine screening) and breast cancer and rated using the American College of Radiology (ACR) Breast Imaging-Reporting and Data System (BI-RADS) 5th edition for MBD. The association between MBD and age was assessed by descriptive analyses and Kruskal-Wallis test. To compare between normal and breast cancer groups, chi-square post hoc tests with Bonferroni adjustment was used. Groups consisted of 73.9% (n = 488) normal group and 26.1% (n = 172) breast cancer group. A significant inverse relationship was demonstrated between age and MBD among the normal ( r = −.319, P .01) and breast cancer group ( r = −.569, P .01). In total, 69% (n = 336) of women in the normal group and 71% (n = 122) in the breast cancer group and 79.1% (n = 159) of the normal group and 100% (n = 48) of the breast cancer group aged 40 to 49 years reported high MBD (ACR BI-RADS c or d). Most of women in both the normal and breast cancer groups evidenced increased MBD. Increased MBD was inversely proportional to age. As MBD has a known link to increased breast cancer risk and the decreased sensitivity of mammography and it is vital that future screening guidelines for Jordanian women consider the unique breast density distribution of this population.
Publisher: Elsevier BV
Date: 06-2013
DOI: 10.1016/J.ACRA.2013.01.018
Abstract: Lymphoscintigraphy may be used for diagnosing secondary lymphedema. Dermal backflow, the presence of radiotracer in dermal lymphatics, is a key clinical feature. Although often reported as present or absent, a scale that assesses the severity of dermal backflow has been previously developed. The aim of this study was to determine the reliability of these two methods of assessment. Sixteen experienced nuclear medicine physicians assessed the quantity of dermal backflow of 57 lymphoscintigraphy scans using a 4-point descriptive scale that was dichotomized for secondary analysis. Each scan included images from four time points for women previously diagnosed with secondary lymphedema (n = 47) and controls (n = 5) five scans were presented twice to examine intraobserver reliability. This was further investigated as 13 physicians viewed the scans again on an Apple iPad2. The physicians rated their confidence in their scoring. Readers were blinded to clinical history. Although both the 2- and 4-point scale had moderate interobserver reliability, the reliability of the 2-point scale was slightly higher (4-point: Fleiss κ = .418, standard error [SE] = .008) 2-point: Fleiss κ = .574, SE = .013). Low interobserver reliability was found when only control subjects were considered (Fleiss κ = 0.055, SE = 0.034). Intraobserver reliability of the five repeated images varied from poor to perfect (Cohen κ = .063 to 1.00), whereas moderate to substantial intraobserver reliability (Cohen's κ = .342 to .752) was found when comparing devices. The readers were highly confident of their scores. Overall, moderate intraobserver and interobserver reliability was found for quantifying dermal backflow with both the 2- and 4-point scale.
Publisher: British Institute of Radiology
Date: 08-2012
DOI: 10.1259/BJR/19989149
Publisher: Oxford University Press (OUP)
Date: 07-06-2017
DOI: 10.1093/RPD/NCX075
Abstract: Cardiac computed tomography angiography (CCTA) is a commonly used diagnostic tool for cardiovascular disease. Despite constant improvements to imaging technologies, the radiation dose to patients from CCTA remains a concern when using this procedure. There remains a need for optimisation of CCTA procedures and accurate dose monitoring to reduce the potential risk of cancer. Establishing diagnostic reference levels (DRLs) allows for the assessment of radiation dose variations, enabling strategies aimed at standardising doses across radiological centres. This systematic review explores the literature on CCTA methodologies that have been used to establish DRLs. A search was carried out using the Web of Science, SCOPUS, Medline, CINAHL and EMBASE databases. Reference lists of published articles were also assessed to identify further articles. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology was employed to evaluate articles for relevance. Articles were included if they assessed DRLs in CCTA. The search resulted in 448 articles, of which, six were included after a thorough screening process. The literature demonstrates a wide dose variation in reported CCTA DRLs ranging from 671 to 1510 mGy cm in DLP. Where reported, CTDIvol DRLs ranged from 26 to 70 mGy. Differences were found in the methodologies used for establishing CCTA DRLs, including the s ling methodology used for identifying suitable patients and scanning protocols. This current review emphasises the need for an international standardisation for DRLs establishment methods, to provide a more comparable global measurement of dose variations across CT sites.
Publisher: Springer Science and Business Media LLC
Date: 13-08-2019
Publisher: Elsevier BV
Date: 02-2008
Publisher: SPIE
Date: 04-03-2010
DOI: 10.1117/12.843233
Publisher: SPIE
Date: 11-03-2014
DOI: 10.1117/12.2035111
Publisher: Elsevier BV
Date: 05-2013
DOI: 10.1016/J.CRAD.2013.01.007
Abstract: The aim of this article is to review the major limitations in current mammography and to describe how these may be addressed by digital breast tomosynthesis (DBT). DBT is a novel imaging technology in which an x-ray fan beam sweeps in an arc across the breast, producing tomographic images and enabling the production of volumetric, three-dimensional (3D) data. It can reduce tissue overlap encountered in conventional two-dimensional (2D) mammography, and thus has the potential to improve detection of breast cancer, reduce the suspicious presentations of normal tissues, and facilitate accurate differentiation of lesion types. This paper reviews the latest studies of this new technology. Issues including diagnostic efficacy, reading time, radiation dose, and level of compression cost and new innovations are considered.
Publisher: British Institute of Radiology
Date: 03-2006
DOI: 10.1259/BJR/60546865
Publisher: SPIE
Date: 28-03-2013
DOI: 10.1117/12.2000705
Publisher: Oxford University Press (OUP)
Date: 27-12-2014
DOI: 10.1093/RPD/NCU365
Abstract: This study aims to review the literature on existing diagnostic reference levels (DRLs) in digital mammography and methodologies for establishing them. To this end, a systematic search through Medline, Cinahl, Web of Science, Scopus and Google scholar was conducted using search terms extracted from three terms: DRLs, digital mammography and breast screen. The search resulted in 1539 articles of which 22 were included after a screening process. Relevant data from the included studies were summarised and analysed. Differences were found in the methods utilised to establish DRLs including test subjects types, protocols followed, conversion factors employed, breast compressed thicknesses and percentile values adopted. These differences complicate comparison of DRLs among countries hence, an internationally accepted protocol would be valuable so that international comparisons can be made.
Publisher: SPIE
Date: 06-03-2008
DOI: 10.1117/12.779435
Publisher: British Institute of Radiology
Date: 09-2012
DOI: 10.1259/BJR/45866310
Publisher: Springer Science and Business Media LLC
Date: 05-05-2022
DOI: 10.1007/S13187-022-02156-W
Abstract: Provision of online and remote specialist education and general continued professional education in medicine is a growing field. For radiology specifically, the ability to access web-based platforms that house high resolution medical images, and the high fidelity of simulated activities is increasingly growing due to positive changes in technology. This study investigates the differences in providing a self-directed specialist radiology education system in two modes: at clinics and in-person workshops. 335 Australian radiologists completed 562 readings of mammogram test sets through the web-based interactive BREAST platform with 325 at conference workshops and 237 at their workplaces. They engaged with test sets with each comprising of 60 mammogram cases (20 cancer and 40 normal). Radiologists marked the location of any cancers and had their performance measured via 5 metrics of diagnostic accuracy. Results show that the location of engagement with BREAST did not yield any significant difference in the performances of all radiologists and the same radiologists between two reading modes ( P 0.05). Radiologists who read screening mammograms for BreastScreen Australia performed better when they completed the test sets at designated workshops ( P 0.05), as was also the case for radiologists who read 100 cases per week ( P 0.05). In contrast, radiologists who read less mammograms frequently recorded better performances in specificity and JAFROC at clinics ( P 0.05). Findings show that remotely accessed online education for specialised training and core skills building in radiology can provide a similar learning opportunity for breast radiologists when compared to on-site dedicated workshops at scientific meetings. For readers with high volumes of mammograms, a workshop setting may provide a superior experience while clinic setting is more helpful to less experienced readers.
Publisher: SAGE Publications
Date: 05-07-2020
Abstract: The low subject contrast between cancerous and fibroglandular tissue could obscure breast abnormalities. To investigate radiologists’ performance for detection of breast cancer in low and high mammographic density (MD) when cases are digitally acquired. A test set of 60 digital mammography cases, of which 20 were cancerous, were examined by 17 radiologists. Mammograms were categorized as low (≤50%) or high ( %) MD and rated for suspicion of malignancy using the Royal Australian and New Zealand College of Radiology (RANZCR) classification system. Radiologist demographics including cases read per year, age, subspecialty, and years of reporting were recorded. Radiologist performance was analyzed by the following metrics: sensitivity specificity area under the receiver operating characteristic (ROC) curve (AUC), location sensitivity, and jackknife free-response ROC (JAFROC) figure of merit (FOM). Comparing high to low MD cases, radiologists showed a significantly higher sensitivity ( P = 0.015), AUC ( P = 0.003), location sensitivity ( P = 0.002), and JAFROC FOM ( P = 0.001). In high compared to low MD cases, radiologists with annual reads and radiologists with no mammographic subspecialty had significantly higher AUC, location sensitivity, and JAFROC FOM. Radiologists with ≥1000 annual reads and radiologists with mammography subspecialty demonstrated a significant increase in location sensitivity in high compared to low MD cases. In this experimental situation, radiologists’ performance was higher when reading cases with high compared to low MD. Experienced radiologists were able to precisely localize lesions in breasts with higher MD. Further studies in unselected screening materials are needed to verify the results.
Publisher: Elsevier BV
Date: 06-2013
DOI: 10.1016/J.ACRA.2013.01.021
Abstract: To investigate the effect of the Joint Photographic Experts Group (JPEG2000) 30:1 and 60:1 lossy compression on the detection of cranial vault fractures when compared to JPEG2000 lossless compression. Fifty cranial computed tomography (CT) images were processed with three different level of JPEG2000 compression (lossless, 30:1 lossy, and 60:1 lossy) creating three sets of images. These were presented to five musculoskeletal specialists and five neuroradiologists. Each reader read at two of the three compression levels. Twenty-two cases contained a single fracture the remaining 28 cases contained no fractures. Observers were asked to identify the presence or absence of a fracture, to locate its site, and rate their degree of confidence. Receiver operating characteristic (ROC), jackknife free-response receiver operating characteristic (JAFROC) and the Dorfman-Berbaum-Metz multiple reader multiple case (DBM-MRMC) analyses were used to explore differences between the lossless and lossy compressed images. JPEG2000 lossless and 30:1 lossy compression demonstrated no significant difference in their performance with JAFROC and DBM-MRMC analysis (P < .416) however, JPEG2000 30:1 lossy compression demonstrated significantly better performance than 60:1 lossy compression (P < .016). A significant increase in misplaced confidence ratings was also seen with 60:1 (P < .037) over 30:1 lossy and lossless compression. JPEG2000 60:1 compression degrades the detection of skull fractures significantly while increasing the confidence with which readers rate fractures compared with 30:1 lossy and lossless compression. JPEG2000 30:1 lossy compression does not significantly change performance when compared to JPEG2000 lossless for the detection of skull fractures on CT.
Publisher: Radiological Society of North America (RSNA)
Date: 03-2011
Abstract: To measure the effect of abnormality-prevalence expectation on experienced radiologists' performance during pulmonary nodular lesion detection on a chest radiograph. A multiobserver receiver operating characteristic (ROC) and eye-position analysis study was performed to assess the effect of prevalence expectation on observer performance. Twenty-two experienced radiologists were ided into three groups and each was asked to interpret 30 (15 abnormal) identical posteroanterior chest images twice and decide if pulmonary lesions were present. Before each viewing, the radiologists were told that the images contained a specific number of abnormal images: group 1: 9 and 15 group 2: 15 and 22 and group 3: 15 and not told. ROC analysis demonstrated that no significant effect could be measured as a function of prevalence expectation (P > .05). However, eye-position analysis showed significant increases in eye movements at higher prevalence expectation rates in terms of the number of fixations per image (group 1: P = .0001 group 2: P = .0001 group 3: P = .001) and the total scrutiny time of each image (group 1: P = .0001 group 2: P = .0283 group 3: P = .028). Overall, findings of this study showed no evidence that the accuracy of expert radiologists is altered due to changing prevalence expectation rates. However, the time spent interpreting each image and the number of fixations increased at higher prevalence rates. Maintenance of diagnostic efficacy has been shown even when circumstances challenge normal observer behavior.
Publisher: Elsevier BV
Date: 08-2013
No related grants have been discovered for Patrick Brennan.