ORCID Profile
0000-0001-7559-3769
Current Organisation
Western Sydney University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Radiation Therapy | Medical Physics | Image Processing | Medical Devices | Engineering And Technology Not Elsewhere Classified | Biomedical Engineering | Medical Physics | Artificial Intelligence and Image Processing
ANZSRC Socio-Economic Objective (SEO)
Cancer and Related Disorders | Medical instrumentation | Diagnostic methods | Physical sciences |
Related Links
Publications
Initial investigation of a novel phantom for simulating optical scattering of dosimetric gels
Publisher: IOP Publishing
Date: 12-2006
Water equivalence of NIPAM based polymer gel dosimeters with enhanced sensitivity for x-ray CT
Publisher: Elsevier BV
Date: 10-2013
The effect of time domain pose filtering on accuracy of small marker based motion correction in awake animal PET
Publisher: IEEE
Date: 10-2012
In the future all accredited radiotherapy physicists should have a PhD
Publisher: Springer Science and Business Media LLC
Date: 21-09-2020
Trends in gel dosimetry: Preliminary bibliometric overview of active growth areas, research trends and hot topics from Gore’s 1984 paper onwards
Publisher: IOP Publishing
Date: 05-2017
Variation of concentration of tetrakis and hydroquinone with post-irradiation times in PAGAT polymer gel dosimeter
Publisher: IOP Publishing
Date: 12-2006
Modelling optical scattering artefacts for varying pathlength in a gel dosimeter phantom
Publisher: IOP Publishing
Date: 16-12-2008
DOI: 10.1088/0031-9155/54/2/007
Abstract: A gelatin phantom containing an optically scattering funnel-shaped region of elevated optical density (OD) was used to examine light-scattering-induced artefacts in a cone-beam optical CT scanner used for gel dosimetry. To simulate polymer gel dosimeters, the opacity was introduced by adding a colloidal scatterer to the gelatin. Scatter results in an underestimate of OD (hence dose). In line profiles of OD taken from 3D reconstructions of the funnel, those profiles with a long pathlength through high OD regions exhibited a 'dishing' (or 'cupping') artefact, while those of short pathlength exhibited the opposite effect-'doming'. These phenomena are accounted for by a model that includes the effect of stray, scattered light.
Investigation of the MAGAS normoxic polymer gel dosimeter with Pyrex glass walls for clinical radiotherapy dosimetry
Publisher: Elsevier BV
Date: 12-2005
Radiation protection in radiotherapy is too conservative
Publisher: Springer Science and Business Media LLC
Date: 03-08-2021
Direct dose to water dosimetry for pretreatment IMRT verification using a modified EPID
Publisher: Wiley
Date: 27-10-2011
DOI: 10.1118/1.3656946
Polymer gel dosimetry using x-ray computed tomography: investigation of the effect of reconstruction technique
Publisher: IOP Publishing
Date: 11-2010
Development of activity standard for 90Y microspheres
Publisher: Elsevier BV
Date: 08-2005
DOI: 10.1016/J.APRADISO.2005.02.002
Abstract: (90)Y microspheres are important therapeutic radiopharmaceuticals used in the treatment of liver cancer through a process known as selective internal radiation therapy. SIR-spheres is a radiopharmaceutical product that is comprised of (90)Y microspheres suspended in sterile, pyrogen-free water for injection into patients. It is necessary to establish for the SIR-spheres production the capability of accurately measuring the activity of this product to a traceable national measurement standard. An activity standard for SIR-spheres was developed from a standard for (90)Y solution, employing a highly quantifiable chemical digestion process. Calibration factors for the manufacturer's ionisation chambers were determined for 1 and 5 ml of the SIR-spheres product placed in Wheaton vials, for both 34% and 44% of (90)Y microsphere concentration.
Assessing space utilisation relative to key performance indicators – how well, not how much, space is used
Publisher: Informa UK Limited
Date: 10-2012
An investigation of motion tracking for freely moving animals in PET
Publisher: IEEE
Date: 10-2010
“Hybrid gold” is the most appropriate open‐access modality for journals like Medical Physics
Publisher: Wiley
Date: 2015
DOI: 10.1118/1.4895979
Polymer gel dosimetry on a multislice computed tomography scanner: Effect of changing parameters on CTDI
Publisher: Elsevier BV
Date: 09-2008
DOI: 10.1016/J.EJMP.2007.11.005
Abstract: Polymer gel dosimetry undertaken on a multislice CT scanner provides an alternative method to conventional dosimetry measurements. Polymer gel dosimeters were used to measure CT radiation doses and compared to TLD and ionization chamber measurements in different diameter phantoms. CTDI was investigated for each of these phantoms for a range of mAs (100-400 mAs), tube voltage (100-135 kV) and nominal slice width (2-32 mm). Linear fits of the CTDI values for mAs show for the smallest phantom diameter an increase in CTDI of 60% for both TLD and polymer gel dosimeters. A similar increase in CTDI of 50% at 100 kVp and 100% for 135 kVp was also noted. It was also shown that slice width variation measured with either polymer gel or TLD was greatest with the smallest slice widths. In summary, it was found that polymer gels can be used as an alternative dosimeter to TLD for the determination of SWDP and subsequent CTDI calculations.
Monte Carlo water-equivalence study of two PRESAGE® formulations for proton beam dosimetry
Publisher: IOP Publishing
Date: 26-06-2013
Light-scattering-induced artifacts in a complex polymer gel dosimetry phantom
Publisher: Optica Publishing Group
Date: 22-04-2009
DOI: 10.1364/AO.48.002427
Abstract: Certain polymer gels become turbid on exposure to ionizing radiation, a property exploited in medical dosimetry to produce three-dimensional dose maps for radiotherapy. These maps can be read using optical computed tomography (CT). A test phantom of complex shape ("layered tube") was developed to investigate the optical properties of polymer gel dosimeters when read using optical CT. Extinction coefficient profiles from tomographically reconstructed slices of the phantom exhibited several artifacts. A simple model invoking scattered light in the gel was able to account for all artifacts, which in a real dosimeter may have been mistaken for other phenomena, resulting in incorrect readings of dose.
Predicting the clonogenic survival of A549 cells after modulated x-ray irradiation using the linear quadratic model
Publisher: IOP Publishing
Date: 16-12-2008
DOI: 10.1088/0031-9155/54/2/002
Abstract: In this study we present two prediction methods, mean dose and summed dose, for predicting the number of A549 cells that will survive after modulated x-ray irradiation. The prediction methods incorporate the dose profile from the modulated x-ray fluence map applied across the cell s le and the linear quadratic (LQ) model. We investigated the clonogenic survival of A549 cells when irradiated using two different modulated x-ray fluence maps. Differences between the measured and predicted surviving fraction were observed for modulated x-ray irradiation. When the x-ray fluence map produced a steep dose gradient across the s le, fewer cells survived in the unirradiated region than expected. When the x-ray fluence map produced a less steep dose gradient across the s le, more cells survived in the unirradiated region than expected. Regardless of the steepness of the dose gradient, more cells survived in the irradiated region than expected for the reference dose range of 1-10 Gy. The change in the cell survival for the unirradiated regions of the two different dose gradients may be an important factor to consider when predicting the number of cells that will survive at the edge of modulated x-ray fields. This investigation provides an improved method of predicting cell survival for modulated x-ray radiation treatment. It highlights the limitations of the LQ model, particularly in its ability to describe the biological response of cells irradiated under these conditions.
Dose resolution in radiotherapy polymer gel dosimetry: effect of echo spacing in MRI pulse sequence
Publisher: IOP Publishing
Date: 22-01-2001
DOI: 10.1088/0031-9155/46/2/312
Abstract: In polymer gel dosimetry using magnetic resonance imaging, the uncertainty in absorbed dose is dependent on the experimental determination of T2. The concept of dose resolution (Dpdelta) of polymer gel dosimeters is developed and applied to the uncertainty in dose related to the uncertainty in T2 from a range of T4 encountered in polymer gel dosimetry. Dpdelta is defined as the minimal separation between two absorbed doses such that they may be distinguished with a given level of confidence, p. The minimum detectable dose (MDD) is Dpdelta as the dose approaches zero. Dpdelta and the minimum detectable dose both give a quantifiable indication of the likely practical limitations and usefulness of the dosimeter. Dpdelta of a polyacrylamide polymer gel dosimeter is presented for customized 32-echo and standard multiple-spin-echo sequences on a clinical MRI scanner. In evaluating uncertainties in T2, a parameter of particular significance in the pulse sequence is the echo spacing (ES). For optimal results, ES should be selected to minimize Dpdelta over a range of doses of interest in polymer gel dosimetry.
A survey of radioactive waste disposal arrangements in UK hospitals and medical research institutions
Publisher: IOP Publishing
Date: 12-1991
Nanoscience and nanotechnology research publications: a comparison between Australia and the rest of the world
Publisher: Springer Science and Business Media LLC
Date: 20-04-2014
The energy response of a T.P.A. Mk-II ionization chamber using GEANT4 Monte Carlo simulation
Publisher: IOP Publishing
Date: 31-05-2007
DOI: 10.1088/0031-9155/52/13/012
Abstract: The low energy model of the GEANT4 Monte Carlo toolkit was used to simulate the energy response of a T.P.A. Mk-II ionization chamber under a variety of different conditions. The s le position resulting in the maximum response along the axial direction of the chamber was obtained. The parameters of the simulation were chosen to account for the maximum effect of the particle backscattering and the setting of most suitable values for the production thresholds and the energy cuts in the GEANT4 Monte Carlo code. The chamber response for different compositions of detector elements was also studied. The simulated radioactive source was a glass oule containing 3.6 ml of the radionuclide in an aqueous solution. The energy response of the chamber at the maximum response was obtained for simulations for (60)Co, (22)Na and (59)Fe nuclides. Verification of the simulated response was obtained using experimental measurements with radioactive sources. The simulated results were in good agreement with the experimentally measured data to within 0.04-2.0%. In the energy range below 200 keV the response curve was complex due to the increase of photoelectric cross sections of the chamber materials. Effects due to backscattering occur at boundaries between chamber elements and also become significant at sites of lead shielding at photon energies above 700 keV. The chamber response for different compositions of detector elements was also studied. The response of the chamber depended highly on the energies of emitting particles, source position and materials used in electrodes and thimble wall.
The influence of rejection of a fraction of the single photoelectron peak in liquid scintillation counting
Publisher: Elsevier BV
Date: 03-2006
A Type VI secretion system encoding locus is required for Bordetella bronchiseptica immunomodulation and persistence in vivo.
Publisher: Public Library of Science (PLoS)
Date: 12-10-2012
Understanding and Compensating for Refraction Errors in Stereo-Optical Tracking During Small Animal PET/SPECT
Publisher: IEEE
Date: 10-2009
A basic study of some normoxic polymer gel dosimeters
Publisher: IOP Publishing
Date: 16-09-2002
DOI: 10.1088/0031-9155/47/19/301
Abstract: Polymer gel dosimeters offer a wide range of potential applications in the three-dimensional verification of complex dose distribution such as in intensity-modulated radiotherapy (IMRT). Until now, however, polymer gel dosimeters have not been widely used in the clinic. One of the reasons is that they are difficult to manufacture. As the polymerization in polymer gels is inhibited by oxygen, all free oxygen has to be removed from the gels. For several years this was achieved by bubbling nitrogen through the gel solutions and by filling the phantoms in a glove box that is perfused with nitrogen. Recently another gel formulation was proposed in which oxygen is bound in a metallo-organic complex thus removing the problem of oxygen inhibition. The proposed gel consists of methacrylic acid, gelatin, ascorbic acid, hydroquinone and copper(II)sulphate and is given the acronym MAGIC gel dosimeter. These gels are fabricated under normal atmospheric conditions and are therefore called 'normoxic' gel dosimeters. In this study, a chemical analysis on the MAGIC gel was performed. The composition of the gel was varied and its radiation response was evaluated. The role of different chemicals and the reaction kinetics are discussed. It was found that ascorbic acid alone was able to bind the oxygen and can thus be used as an anti-oxidant in a polymer gel dosimeter. It was also found that the anti-oxidants N-acetyl-cysteine and tetrakis(hydroxymethyl)phosphonium were effective in scavenging the oxygen. However, the rate of oxygen scavenging is dependent on the anti-oxidant and its concentration with tetrakis(hydroxymethyl)phosphonium being the most reactive anti-oxidants. Potentiometric oxygen measurements in solution provide an easy way to get a first impression on the rate of oxygen scavenging. It is shown that cupper(II)sulphate operates as a catalyst in the oxidation of ascorbic acid. We, therefore, propose some new normoxic gel formulations that have a less complicated chemical formulation than the MAGIC gel.
A decision support model and tool to assist financial decision-making in universities
Publisher: Informa UK Limited
Date: 02-01-2015
Refraction-compensated motion tracking of unrestrained small animals in positron emission tomography
Publisher: Elsevier BV
Date: 08-2012
DOI: 10.1016/J.MEDIA.2012.04.005
Abstract: Motion-compensated radiotracer imaging of fully conscious rodents represents an important paradigm shift for preclinical investigations. In such studies, if motion tracking is performed through a transparent enclosure containing the awake animal, light refraction at the interface will introduce errors in stereo pose estimation. We have performed a thorough investigation of how this impacts the accuracy of pose estimates and the resulting motion correction, and developed an efficient method to predict and correct for refraction-based error. The refraction model underlying this study was validated using a state-of-the-art motion tracking system. Refraction-based error was shown to be dependent on tracking marker size, working distance, and interface thickness and tilt. Correcting for refraction error improved the spatial resolution and quantitative accuracy of motion-corrected positron emission tomography images. Since the methods are general, they may also be useful in other contexts where data are corrupted by refraction effects.
Artificial intelligence (AI) will enable improved diagnosis and treatment outcomes
Publisher: Springer Science and Business Media LLC
Date: 09-08-2021
Investigation of kinetic friction using an iPhone
Publisher: IOP Publishing
Date: 22-09-2016
Comments on the measurement of activity in vials and syringes using a radionuclide assay calibrator
Publisher: IOP Publishing
Date: 12-1993
The impact of MLC transmitted radiation on EPID dosimetry for dynamic MLC beams
Publisher: Wiley
Date: 10-03-2008
DOI: 10.1118/1.2885368
Abstract: The purpose of this study was to experimentally quantify the change in response of an amorphous silicon (a-Si) electronic portal imaging device (EPID) to dynamic multileaf collimator (dMLC) beams with varying MLC-transmitted dose components and incorporate the response into a commercial treatment planning system (TPS) EPID prediction model. A combination of uniform intensity dMLC beams and static beams were designed to quantify the effect of MLC transmission on EPID response at the central axis of 10 x 10 cm2 beams, at off-axis positions using wide dMLC beam profiles, and at different field sizes. The EPID response to MLC transmitted radiation was 0.79 +/- 0.02 of the response to open beam radiation at the central axis of a 10 x 10 cm2 field. The EPID response to MLC transmitted radiation was further reduced relative to the open beam response with off-axis distance. The EPID response was more sensitive to field size changes for MLC transmitted radiation compared to open beam radiation by a factor of up to 1.17 at large field sizes. The results were used to create EPID response correction factors as a function of the fraction of MLC transmitted radiation, off-axis distance, and field size. Software was developed to apply the correction factors to each pixel in the TPS predicted EPID image. The corrected images agreed more closely with the measured EPID images in areas of intensity modulated fields with a large fraction of MLC transmission and, as a result the accuracy of portal dosimetry with a-Si EPIDs can be improved. Further investigation into the detector response function and the radiation source model are required to achieve improvements in accuracy for the general case.
Light scattering artefacts in a funnel phantom using optical CT
Publisher: IOP Publishing
Date: 05-2009
Investigation of radiological properties and water equivalency of PRESAGE® dosimeters
Publisher: Wiley
Date: 31-03-2011
DOI: 10.1118/1.3561509
Abstract: PRESAGE is a dosimeter made of polyurethane, which is suitable for 3D dosimetry in modern radiation treatment techniques. Since an ideal dosimeter is radiologically water equivalent, the authors investigated water equivalency and the radiological properties of three different PRESAGE formulations that differ primarily in their elemental compositions. Two of the formulations are new and have lower halogen content than the original formulation. The radiological water equivalence was assessed by comparing the densities, interaction probabilities, and radiation dosimetry properties of the three different PRESAGE formulations to the corresponding values for water. The relative depth doses were calculated using Monte Carlo methods for 50, 100, 200, and 350 kVp and 6 MV x-ray beams. The mass densities of the three PRESAGE formulations varied from 5.3% higher than that of water to as much as 10% higher than that of water for the original formulation. The probability of photoelectric absorption in the three different PRESAGE formulations varied from 2.2 times greater than that of water for the new formulations to 3.5 times greater than that of water for the original formulation. The mass attenuation coefficient for the three formulations is 12%-50% higher than the value for water. These differences occur over an energy range (10-100 keV) in which the photoelectric effect is the dominant interaction. The collision mass stopping powers of the relatively lower halogen-containing PRESAGE formulations also exhibit marginally better water equivalency than the original higher halogen-containing PRESAGE formulation. Furthermore, the depth dose curves for the lower halogen-containing PRESAGE formulations are slightly closer to that of water for a 6 MV beam. In the kilovoltage energy range, the depth dose curves for the lower halogen-containing PRESAGE formulations are in better agreement with water than the original PRESAGE formulation. Based on the results of this study, the new PRESAGE formulations with lower halogen content are more radiologically water equivalent overall than the original formulation. This indicates that the new PRESAGE formulations are better suited to clinical applications and are more accurate dosimeters and phantoms than the original PRESAGE formulation. While correction factors are still needed to convert the dose measured by the dosimeter to an absorbed dose in water in the kilovoltage energy range, these correction factors are considerably smaller for the new PRESAGE formulations compared to the original PRESAGE and the existing polymer gel dosimeters.
P-values should not be used for decision making in the practice of clinical medical physics
Publisher: Springer Science and Business Media LLC
Date: 26-10-2021
The Bland–Altman analysis: Does it have a role in assessing radiation dosimeter performance relative to an established standard?
Publisher: Elsevier BV
Date: 08-2010
SU-GG-I-148: Novel Use of Polymer Gels for Internal Radionulide Dosimetry of Tc-99m
Publisher: Wiley
Date: 06-2008
DOI: 10.1118/1.2961546
Dosimetry aspects of a non-diffusing genipin–gelatin gel
Publisher: Elsevier BV
Date: 02-2013
Tracking and characterizing the head motion of unanaesthetized rats in positron emission tomography
Publisher: The Royal Society
Date: 20-06-2012
Abstract: Positron emission tomography (PET) is an important in vivo molecular imaging technique for translational research. Imaging unanaesthetized rats using motion-compensated PET avoids the confounding impact of anaesthetic drugs and enables animals to be imaged during normal or evoked behaviour. However, there is little published data on the nature of rat head motion to inform the design of suitable marker-based motion-tracking set-ups for brain imaging—specifically, set-ups that afford close to uninterrupted tracking. We performed a systematic study of rat head motion parameters for unanaesthetized tube-bound and freely moving rats with a view to designing suitable motion-tracking set-ups in each case. For tube-bound rats, using a single appropriately placed binocular tracker, uninterrupted tracking was possible greater than 95 per cent of the time. For freely moving rats, simulations and measurements of a live subject indicated that two opposed binocular trackers are sufficient (less than 10% interruption to tracking) for a wide variety of behaviour types. We conclude that reliable tracking of head pose can be achieved with marker-based optical-motion-tracking systems for both tube-bound and freely moving rats undergoing PET studies without sedation.
The relationship between radiation-induced chemical processes and transverse relaxation times in polymer gel dosimeters
Publisher: IOP Publishing
Date: 14-03-2001
DOI: 10.1088/0031-9155/46/4/311
Abstract: The effects of ionizing radiation in different compositions of polymer gel dosimeters are investigated using FT-Raman spectroscopy and NMR T2 relaxation times. The dosimeters are manufactured from different concentrations of comonomers (acrylamide and N,N'-methylene-bis-acrylamide) dispersed in different concentrations of an aqueous gelatin matrix. Results are analysed using a model of fast exchange of magnetization between three proton pools. The fraction of protons in each pool is determined using the known chemical composition of the dosimeter and FT-Raman spectroscopy. Based on these results, the physical and chemical processes in interplay in the dosimeters are examined in view of their effect on the changes in T2. The precipitation of growing macroradicals and the scavenging of free radicals by gelatin are used to explain the rate of polymerization. The model describes the changes in T2 as a function of the absorbed dose up to 50 Gy for the different compositions. This is expected to aid the theoretical design of new, more efficient dosimeters, since it was demonstrated that the optimum dosimeter (i.e, with the lowest dose resolution) must have a range of relaxation times which match the range of T2 values which can be determined with the lowest uncertainty using an MRI scanner.
Calibration of the Capintec CRC-712M dose calibrator for 18F
Publisher: Elsevier BV
Date: 04-2006
DOI: 10.1016/J.APRADISO.2005.09.006
Abstract: Primary standardisation was performed on a solution of (18)F using the 4pibeta-gamma coincidence counting efficiency-tracing extrapolation method with (60)Co used as a tracer nuclide. The result was used to calibrate the ANSTO secondary standard ionisation chamber which is used to disseminate Australian activity standards for gamma emitters. Using the secondary activity standard for (18)F, the Capintec CRC-712M dose calibrator at the Australian National Medical Cyclotron (NMC) Positron Emission Tomography (PET) Quality Control (QC) Section was calibrated. The dial setting number recommended by the manufacturer for the measurement of the activity of (18)F is 439. In this work, the dial setting numbers for the activity measurement of the solution of (18)F in Wheaton vials were experimentally determined to be 443+/-12, 446+/-12, 459+/-11, 473+/-15 for 0.1, 1, 4.5 and 9ml solution volumes, respectively. The uncertainties given above are expanded uncertainties (k=2) giving an estimated level of confidence of 95%. The activities determined using the manufacturer recommended setting number 439 are 0.8%, 1.4%, 4.0% and 6.5% higher than the standardised activities, respectively. It is recommended that a single dial setting number of 459 determined for 4.5ml is used for 0.1-9ml solution in Wheaton vials in order to simplify the operation procedure. With this setting the expended uncertainty (k=2) in the activity readout from the Capintec dose calibrator would be less than 6.2%.
Experimental study of attenuation properties of normoxic polymer gel dosimeters
Publisher: IOP Publishing
Date: 10-2004
DOI: 10.1088/0031-9155/49/20/N01
Abstract: The change in linear attenuation coefficient with absorbed dose has been investigated for aqueous polyacrylamide, gelatine and tetrakis (PAGAT) and aqueous methacrylic acid, gelatine and tetrakis (MAGAT) normoxic polymer gel dosimeters using tetrakis (hydroxy methyl) phosphonium chloride as the antioxidant. The measured linear attenuation coefficient increased linearly with absorbed dose up to 15 Gy for PAGAT gels and 10 Gy for MAGAT gels. Computerized tomography (CT) numbers or Hounsfield units (H) were calculated from the linear attenuation coefficients and compared with values obtained using a CT scanner. Both calculated and measured CT numbers followed a similar pattern when fitted with a biexponential curve. The CT numbers obtained from linear attenuation measurements were found to be greater than that obtained with the CT scanner for both PAGAT and MAGAT polymer gels. The H-dose sensitivities of the MAGAT and PAGAT polymer gel dosimeters measured on a CT scanner were calculated to be (0.85 +/- 0.08) H Gy(-1) and (0.31 +/- 0.03) H Gy(-1), respectively. The H-dose sensitivities of the MAGAT and PAGAT polymer gel dosimeters from attenuation measurements were found to be (1.10 +/- 0.66) H Gy(-1) and (0.34 +/- 0.01) H Gy(-1), respectively.
The characterisation of a genipin-gelatin gel dosimeter
Publisher: IOP Publishing
Date: 11-2010
A preliminary investigation of cell growth after irradiation using a modulated x-ray intensity pattern
Publisher: IOP Publishing
Date: 12-07-2006
DOI: 10.1088/0031-9155/51/15/003
Abstract: In this study we have investigated a spatial distribution of cell growth after their irradiation using a modulated x-ray intensity pattern. An A549 human non-small cell lung cancer cell line was grown in a 6-well culture. Two of the wells were the unirradiated control wells, whilst another two wells were irradiated with a modulated x-ray intensity pattern and the third two wells were uniformly irradiated. A number of plates were incubated for various times after irradiation and stained with crystal violet. The spatial distribution of the stained cells within each well was determined by measurement of the crystal violet optical density at multiple positions in the plate using a microplate photospectrometer. The crystal violet optical density for a range of cell densities was measured for the unirradiated well and this correlated with cell viability as determined by the MTT cell viability assay. An exponential dose response curve was measured for A549 cells from the average crystal violet optical density in the uniformly irradiated well up to a dose of 30 Gy. By measuring the crystal violet optical density distribution within a well the spatial distribution of cell growth after irradiation with a modulated x-ray intensity pattern can be plotted. This method can be used for in vitro investigation into the changes in radiation response associated with treatment using intensity modulated radiation therapy (IMRT).
Preliminary investigation of PAGAT polymer gel radionuclide dosimetry of Tc-99m
Publisher: IOP Publishing
Date: 05-2009
Study of dosimetric water equivalency of PRESAGE® for megavoltage and kilovoltage x-ray beams
Publisher: IOP Publishing
Date: 11-2010
SU‐FF‐T‐52: A Test for Water Equivalence of Solid Phantoms in the Kilovoltage Photon Energy Range
Publisher: Wiley
Date: 06-2007
DOI: 10.1118/1.2760700
Measurement of ultrasonic attenuation coefficient in polymer gel dosimeters
Publisher: IOP Publishing
Date: 02-10-2003
DOI: 10.1088/0031-9155/48/20/N01
Abstract: A technique is described for investigation of the ultrasonic attenuation coefficient for evaluation of absorbed dose in polymer gel dosimeters. Using this technique the attenuation coefficient as a function of absorbed dose in PAG and MAGIC polymer gel dosimeters was measured. The ultrasonic attenuation coefficient dose sensitivity for PAG was found to be 2.9 +/- 0.3 dB m(-1) Gy(-1) and for MAGIC gel 4.2 +/- 0.3 dB m(-1) Gy(-1). Unlike previous studies of ultrasonic attenuation in polymer gel dosimeters this technique enables a direct measure of the attenuation coefficient.
Effects of glass and backscatter on measurement of absorbed dose in polyacrylamide gel (PAG) dosimeters
Publisher: IOP Publishing
Date: 21-09-2000
DOI: 10.1088/0031-9155/45/10/402
Abstract: Different methodologies are used for calibrating polyacrylamide gel (PAG) dosimeters. One methodology involves injecting nitrogen-filled glass vials with polymer gel. Due to the vials being pre-filled with nitrogen, a nitrogen-filled space remains in the glass vial above the gel. The glass vial is then irradiated using ionizing radiation to polymerize the PAG. Monte Carlo simulations were performed to examine the effects on the radiation field due to the glass vial and the lack of backscatter material due to the nitrogen-filled space. Results for two different formulations of PAG indicated that the influence of the glass and the nitrogen-filled space are negligible.
SU‐GG‐T‐383: Investigation of Water Equivalency of PRESAGE Dosimeters for Electron Beam Radiotherapy
Publisher: Wiley
Date: 06-2010
DOI: 10.1118/1.3468780
Radiological properties of the PRESAGE and PAGAT polymer dosimeters
Publisher: Elsevier BV
Date: 12-2008
DOI: 10.1016/J.APRADISO.2008.06.005
Abstract: The radiological properties of the PRESAGE and PAGAT polymer dosimeters have been investigated and their water equivalence determined for use in radiotherapy dosimetry. The radiological water equivalence of each of the polymer dosimeters was determined by comparing the photon and electron interaction cross-sections over the 10 keV-20 MeV energy range and by Monte Carlo modelling the depth dose from a linear accelerator using the BEAMnrc software package. PRESAGE was found to have an effective Z-value and mass density (kgm(-3)) approximately 17% and 10% higher than water, respectively. A maximum difference of 85% was discovered in the photoelectric interaction probability curve of PRESAGE when compared to water over the energy range 10-100 keV, partially due to the Z(3) dependence of the photoelectric effect. The mass radiative stopping power ratios and mass scattering power ratios were both found to have less than 9% difference from water. The depth dose for PRESAGE from a 6MV photon beam had an absolute percentage difference to water of less than 2% and a relative percentage difference of less than 8%. The mass density of PAGAT was found to be 2.6% higher than water due to its high gelatine and monomer concentration. The cross-sectional attenuation and absorption coefficient ratios were found to be within 5% for energies between 10 and 100 keV and within 1% for energies between 100 keV and 20 MeV. The mass collisional stopping power, mass radiative stopping power and mass scattering power ratios were all less than 1% over the energy range studied. The depth dose had an absolute percentage difference to water of less than 1% and a relative percentage difference of less than 2.5%. These results indicate that the PAGAT polymer gel formulation is more radiological water equivalent than the PRESAGE formulation. However, the PRESAGE dosimeter offers some advantages in terms of ease of use and its lack of water equivalence may be overcome with dosimetric correction factors.
EPID dosimetry: Effect of different layers of materials on absorbed dose response
Publisher: Wiley
Date: 23-11-2009
DOI: 10.1118/1.3245886
Abstract: Commercial EPIDs are normally used in indirect detection mode (iEPID) where incident x-ray photons are converted to optical photons in a phosphor scintillator, which are then detected by a photodiode array. The EPIDs are constructed from a number of nonwater equivalent materials which affect the dose response of the detector. The so-called direct detection EPIDs (dEPIDs), operating without the phosphor layer, have been reported to display dose response close to in-water data. In this study, the effect that different layers of materials in the EPID have on the dose response was experimentally investigated and evaluated with respect to changes in field size response and beam profiles. An iEPID was disassembled and the different layers of materials were removed or replaced with other materials. Data were also obtained on and off the support arm and with a sheet of opaque paper blocking the optical photons from the gadolinium oxysulfide (Gd2S2O:Tb) phosphor layer. Field size response was measured for field sizes ranging from 2 x 2 to 25 x 25 cm2, and profiles for the 25 x 25 cm2 beams were extracted from the data. The iEPID configuration was found to be very sensitive to backscatter. The increases in output with solid water backscatter compared to the no backscatter case were 14.7% and 6.6% at the largest field size investigated for the 6 and 18 MV beams, respectively. The Gd2S2O:Tb phosphor layer had a large influence on field size response as well as beam profiles for 6 MV photons, while no major effects were observed for the 18 MV beam. For 18 MV large differences in dose response were found when the standard 1 mm Cu buildup was changed for dmax equivalent Cu or solid water buildup, indicating that head scatter largely influences dose response for this energy. When the optical photons originating in the Gd2S2O:Tb layer were blocked from reaching the photodiodes, both field size output data and beam profiles corresponded well with data obtained in the dEPID configuration as well as reference ion chamber data for both energies. As expected, changing the layers of material in the EPID had a dramatic effect on dose response, which was often quite complex. For 6 MV, the complex dose response is mainly caused by the optical photons from the Gd2S2O:Tb layer, while insufficient filtering of scattered radiation largely affects the dose response for the 18 MV beam. The iEPID was also found to be very sensitive to backscatter for both energies. Blocking the optical photons created in the Gd2S2O:Tb layer essentially changed the iEPID configuration into the dEPID configuration, thus demonstrating great potential for a system that can be optimized for both imaging and dosimetry.
The water equivalence of solid phantoms for low energy photon beams
Publisher: Wiley
Date: 28-07-2010
DOI: 10.1118/1.3462558
Abstract: To compare and evaluate the dosimetric water equivalence of several commonly used solid phantoms for low energy photon beams. A total of ten different solid phantom materials was used in the study. The PENELOPE Monte Carlo code was used to calculate depth doses and beam profiles in all the phantom materials as well as the dose to a small water voxel at the surface of the solid phantom. These doses were compared to the corresponding doses calculated in a water phantom. The primary photon beams used ranged in energy from 50 to 280 kVp. A number of phantom materials had excellent agreement in dose compared to water for all the x-ray beam energies studied. RMI457 Solid Water, Virtual Water, PAGAT, A150, and Plastic Water DT all had depth doses that agreed with those in water to within 2%. For these same phantom materials, the dose changes in the water voxel at the surface of the solid phantom were within 2%, except for A150, which agreed to within 2.7%. By comparison, the largest differences in depth doses occurred for Plastic Water (-21.7%) and polystyrene (17.6%) for the 50 kVp energy photon beam and 8 cm diameter field size. Plastic Water gave the largest difference in the normalized beam profiles with differences of up to 3.5% as compared to water. Surface dose changes, due to the presence of the solid phantom acting as the backscatter material, were found to be up to 9.1% for polystyrene with significant differences also found for Plastic Water, PMMA, and RW3 phantoms. The following solid phantoms can be considered water equivalent and are recommended for relative dosimetry of low energy photon beams: A150, PAGAT, Plastic Water DT, RMI457 Solid Water, and Virtual Water. However, the following solid phantoms give significant differences, compared to water, in depth doses, profiles, and/or in surface doses due to backscatter changes: Plastic Water, PMMA, polystyrene, PRESAGE, and RW3.
Refraction-compensated motion tracking of unrestrained animals in PET
Publisher: IEEE
Date: 10-2010
High-resolution gel dosimetry of a HDR brachytherapy source using normoxic polymer gel dosimeters: Preliminary study
Publisher: Elsevier BV
Date: 09-2006
Investigation of ultrasonic properties of PAG and MAGIC polymer gel dosimeters
Publisher: IOP Publishing
Date: 03-12-2002
DOI: 10.1088/0031-9155/47/24/307
Abstract: Ultrasonic speed of propagation and attenuation were investigated as a function of absorbed radiation dose in PAG and MAGIC polymer gel dosimeters. Both PAG and MAGIC gel dosimeters displayed a dependence of ultrasonic parameters on absorbed dose with attenuation displaying significant changes in the dose range investigated. The ultrasonic attenuation dose sensitivity at 4 MHz in MAGIC gels was determined to be 4.7 +/- 0.3 dB m(-1) Gy(-1) and for PAG 3.9 +/- 0.3 dB m(-1) Gy(-1). Ultrasonic speed dose sensitivities were 0.178 +/- 0.006 m s(-1) Gy(-1) for MAGIC gel and -0.44 +/- 0.02 m s(-1) Gy(-1) for PAG. Density and compressional elastic modulus were investigated to explain the different sensitivities of ultrasonic speed to radiation for PAG and MAGIC gels. The different sensitivities were found to be due to differences in the compressional elastic modulus as a function of dose for the two formulations. To understand the physical phenomena underlying the increase in ultrasonic attenuation with dose, the viscoelastic properties of the gels were studied. Results suggest that at ultrasonic frequencies, attenuation in polymer gel dosimeters is primarily due to volume viscosity. It is concluded that ultrasonic attenuation significantly increases with absorbed dose. Also, the ultrasonic speed in polymer gel dosimeters is affected by changes in dosimeter elastic modulus that are likely to be a result of polymerization. It is suggested that ultrasound is a sufficiently sensitive technique for polymer gel dosimetry.
SU‐GG‐T‐299: An Evaluation of Solid Phantoms for the Dosimetry of Low Energy Photon Beams
Publisher: Wiley
Date: 06-2008
DOI: 10.1118/1.2963117
Correction to: P‑values should not be used for decision making in the practice of clinical medical physics
Publisher: Springer Science and Business Media LLC
Date: 22-11-2021
SU‐GG‐T‐382: Evaluation of Genipin Gel Dosimeter for Depth Dose Measurement of X‐Ray Beams
Publisher: Wiley
Date: 06-2010
DOI: 10.1118/1.3468779
Issues involved in the quantitative 3D imaging of proton doses using optical CT and chemical dosimeters
Publisher: IOP Publishing
Date: 02-01-2015
Dose$ndash$response stability and integrity of the dose distribution of various polymer gel dosimeters
Publisher: IOP Publishing
Date: 03-07-2002
DOI: 10.1088/0031-9155/47/14/307
Abstract: In this study the stability of different polymer gel dosimeters is investigated. Further to a previous chemical stability study on a (6%T, 50%C) PAG gel, the change in slope and intercept of the linear part of the R2-dose plot is recorded with time for different gel formulations. In addition to this R2-dose-response stability study, the dose edge of a half-blocked field was recorded with time. Three different PAG type polymer gels, a hydroxyethyl acrylate (HEA) gel and two different normoxic polymer gels were investigated. In the PAG type polymer gels, the relative concentration of gelatin and comonomers was varied in order to study the influence of the different components, that constitute the dosimeter, on the stability. It is shown that the R2-dose-response stability is largely determined by the chemical composition of the gel dosimeters. All the PAG gel dosimeters and the normoxic gel dosimeters are found to preserve the integrity of the dose distribution up to 22 days after irradiation. The half-life of the change in dose sensitivity of a MAGIC gel is found to be 18 h compared to 5.7 h for a (6%T, 50%C) PAG gel. A maximum relative decrease in dose sensitivity of 21% was noted for the MAGIC gel compared to an increase of 50% for a (6%T, 50%C) PAG gel. A loss of integrity of the dose distribution was found in the HEA gel.
Water and tissue equivalence of a new PRESAGE® formulation for 3D proton beam dosimetry: A Monte Carlo study
Publisher: Wiley
Date: 11-2012
DOI: 10.1118/1.4757922
Abstract: To evaluate the water and tissue equivalence of a new PRESAGE(®) 3D dosimeter for proton therapy. The GEANT4 software toolkit was used to calculate and compare total dose delivered by a proton beam with mean energy 62 MeV in a PRESAGE(®) dosimeter, water, and soft tissue. The dose delivered by primary protons and secondary particles was calculated. Depth-dose profiles and isodose contours of deposited energy were compared for the materials of interest. The proton beam range was found to be ≈27 mm for PRESAGE(®), 29.9 mm for soft tissue, and 30.5 mm for water. This can be attributed to the lower collisional stopping power of water compared to soft tissue and PRESAGE(®). The difference between total dose delivered in PRESAGE(®) and total dose delivered in water or tissue is less than 2% across the entire water∕tissue equivalent range of the proton beam. The largest difference between total dose in PRESAGE(®) and total dose in water is 1.4%, while for soft tissue it is 1.8%. In both cases, this occurs at the distal end of the beam. Nevertheless, the authors find that PRESAGE(®) dosimeter is overall more tissue-equivalent than water-equivalent before the Bragg peak. After the Bragg peak, the differences in the depth doses are found to be due to differences in primary proton energy deposition PRESAGE(®) and soft tissue stop protons more rapidly than water. The dose delivered by secondary electrons in the PRESAGE(®) differs by less than 1% from that in soft tissue and water. The contribution of secondary particles to the total dose is less than 4% for electrons and ≈1% for protons in all the materials of interest. These results demonstrate that the new PRESAGE(®) formula may be considered both a tissue- and water-equivalent 3D dosimeter for a 62 MeV proton beam. The results further suggest that tissue-equivalent thickness may provide better dosimetric and geometric accuracy than water-equivalent thickness for 3D dosimetry of this proton beam.
An investigation of dose changes for therapeutic kilovoltage x‐ray beams with underlying lead shielding
Publisher: Wiley
Date: 26-06-2007
DOI: 10.1118/1.2748103
Abstract: Kilovoltage x-ray beams are used to treat cancer on or close to the skin surface. Many clinical cases use high atomic number materials as shielding to reduce dose to underlying healthy tissues. In this work, we have investigated the effect on both the surface dose and depth doses in a water phantom with lead shielding at depth in the phantom. The EGSnrc Monte Carlo code was used to simulate the water phantom and to calculate the surface doses and depth doses using primary x-ray beam spectra derived from an analytical model. The x-ray beams were in the energy range of 75-135 kVp with field sizes of 2, 5 and 8 cm diameter. The lead sheet was located beneath the water surface at depths ranging from 0.5-7.5 cm. The surface dose decreased as the lead was positioned closer to the water surface and as the field size was increased. The variation in surface dose as a function of x-ray beam energy was only small but the maximum reduction occurred for the 100 kVp x-ray beam. For the 8 cm diameter field with the lead at 1 cm depth and using the 100 kVp x-ray beam, the surface dose was reduced to 0.898 of the surface dose in the water phantom only. Measured surface dose changes, using a Farmer-type ionization chamber, agreed with the Monte Carlo calculated doses. Calculated depth doses in water with a lead sheet positioned below the surface showed that the dose fall-off increased as the lead was positioned closer to the water surface as compared to the depth dose in the water phantom only. Monte Carlo calculations of the total x-ray beam spectrum at the water surface showed that the total fluence decreased due to a reduction in backscatter from within the water and very little backscatter from the lead. The mean energy of the x-ray spectrum varied less than 1 keV, with the lead at 1 cm beneath the water phantom surface. As the Monte Carlo calculations showed good agreement with the measured results, this method can be used to verify surface dose changes in clinical situations where measurements are difficult. The clinical impact of the use of lead must be considered in the dose prescription for patients being treated with kilovoltage x-ray beams.
Effect of saccharide additives on response of ferrous–agarose–xylenol orange radiotherapy gel dosimeters
Publisher: Wiley
Date: 15-08-2003
DOI: 10.1118/1.1597771
Abstract: Glucose, sucrose, starch, and locust bean gum have been used as additives to the ferrous-agarose-xylenol orange (FAX) gel dosimeter. The saccharide enhanced dosimeters were found to have a higher dose sensitivity over a standard FAX gel as measured by both optical density change and magnetic resonance imaging (MRI). With optical density measurement, OD-dose sensitivity increases were up to 55% for glucose, 122% for sucrose and 43% for starch, while locust bean gum did not give a consistent response. With MRI, R1-dose sensitivity increases were up to 178% with sucrose addition. The FAX gel with sucrose was studied in greatest detail. The OD-dose sensitivity dependence on cooling rate was reduced for the sucrose FAX gel over the standard FAX gel, which has significant implications for uniform dose sensitivity in large gel phantoms. The thermal oxidation rate in the sucrose FAX gel was up to 2.3 times higher than in the standard gel. The OD-dose sensitivity of oxygenated sucrose FAX gels was 4.3 times greater than standard FAX gels, while continued enhancement in OD-dose sensitivity with increased sucrose concentrations beyond 2.0 g/l was found only for the oxygenated sucrose FAX gels. Both the molar absorption coefficient of the ferric ion-xylenol orange complex at 543 nm and gel pH were not affected by the presence of sucrose, with the implication that the higher OD-dose sensitivity of gels with saccharides is due to increased chain reaction production of ferric ions.
Polymer gel dosimetry
Publisher: IOP Publishing
Date: 11-02-2010
Initial investigation of a novel light-scattering gel phantom for evaluation of optical CT scanners for radiotherapy gel dosimetry
Publisher: IOP Publishing
Date: 05-2007
DOI: 10.1088/0031-9155/52/10/017
Abstract: There is a need for stable gel materials for phantoms used to validate optical computerized tomography (CT) scanners used in conjunction with radiation-induced polymerizing gel dosimeters. Phantoms based on addition of light-absorbing dyes to gelatine to simulate gel dosimeters have been employed. However, to more accurately simulate polymerizing gels one requires phantoms that employ light-scattering colloidal suspensions added to the gel. In this paper, we present the initial results of using an optical CT scanner to evaluate a novel phantom in which radiation-exposed polymer gels are simulated by the addition of colloidal suspensions of varying turbidity. The phantom may be useful as a calibration transfer standard for polymer gel dosimeters. The tests reveal some phenomena peculiar to light-scattering gels that need to be taken into account when calibrating polymer gel dosimeters.
Chondrichthyan research in South America: Endocrinology overview and research trends over 50 years (1967–2016) compared to the rest of the world
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.YGCEN.2018.06.005
Abstract: The endocrine system plays a crucial role in regulating the activity of cells and organs among vertebrates, including the class Chondrichthyes. Accordingly, Chondrichthyan endocrinology publications have been steadily increasing in the global literature. However, while interest in South American Chondrichthyan research has been growing over the last 50 years, the field of endocrinology related to Chondrichthyans has been limited. Understanding the trajectory of a scientific discipline assists researchers and stakeholders in making decisions regarding which research areas require further attention. Further, visualisation techniques based on bibliometric analysis of scientific publications assist in understanding fluctuations in the trends of specific research fields over time. In this study, Chondrichthyan research publications over time were analysed by creating visualisation maps using VOSviewer bibliometric software. Trends in South America Chondrichthyan research with an emphasis on endocrinology were explored over a 50-year period (1967-2016). These trends were compared with Chondrichthyans research worldwide for the more recent 15-year period (2002-2016). The number of South America Chondrichthyan scientific publications increased from six during the 1967-1981 period to 112 in 2016. However, only eight papers were found published in the area of Chondrichthyan endocrinology research. Fisheries, reproduction and taxonomy were the dominate research areas in South America over the 50 years. For the more recent 15 years, South American publications comprised 11% of the total literature published globally. While South America research outputs fluctuated closely with global research trends, differences appeared when comparing areas of growth. This study describes the trends in Chondrichthyan research literature globally and more specifically in South America. Although South American countries may never contribute to the same scale as the wider international scientific community, the future of Chondrichthyans would strongly benefit from the contributions of the many erse research groups around the world.
A preliminary study of the measurement of slice-width dose profiles (SWDP) on diagnostic x-ray CT scanners using PAGAT polymer gel dosimeters with optical CT read-out
Publisher: IOP Publishing
Date: 12-2006
Computer tomography dose index measurements on a multislice CT scanner using polymer gels
Publisher: IOP Publishing
Date: 12-2006
Gel dosimetry provides the optimal end‐to‐end quality assurance dosimetry for MR‐linacs
Publisher: Wiley
Date: 04-06-2020
DOI: 10.1002/MP.14239
The index is the best measure of a scientist's research productivity
Publisher: Wiley
Date: 05-03-2009
DOI: 10.1118/1.3089421
SU‐E‐T‐149: 3D Proton Gel Dosimetry
Publisher: Wiley
Date: 06-2011
DOI: 10.1118/1.3612100
The future of radiotherapy is molecular
Publisher: Springer Science and Business Media LLC
Date: 17-08-2020
Ultrasonic absorption in polymer gel dosimeters
Publisher: Elsevier BV
Date: 09-2003
DOI: 10.1016/S0041-624X(03)00153-7
Abstract: Ultrasonic absorption in polymer gel dosimeters was investigated. An ultrasonic interferometer was used to study the frequency (f) dependence of the absorption coefficient (alpha) in a polyacrylamide gel dosimeter (PAG) in the frequency range 5-20 MHz. The frequency dependence of ultrasonic absorption deviated from that of an ideal viscous fluid. The presence of relaxation mechanisms was evidenced by the frequency dependence of alpha/f(2) and the dispersion in ultrasonic velocity. It was concluded that absorption in polymer gel dosimeters is due to a number of relaxation processes which may include polymer-solvent interactions as well as relaxation due to motion of polymer side groups. The dependence of ultrasonic absorption on absorbed dose and formulation was also investigated in polymer gel dosimeters as a function of pH and chemical composition. Changes in dosimeter pH and chemical composition resulted in a variation in ultrasonic dose response curves. The observed dependence on pH was considered to be due to pH induced modifications in the radiation yield while changes in chemical composition resulted in differences in polymerisation kinetics.
7th International Conference on 3D Radiation Dosimetry (IC3DDose)
Publisher: IOP Publishing
Date: 26-06-2013
Preliminary characterization of PRESAGE® for 3D dosimetry of 62 MeV proton beam
Publisher: IOP Publishing
Date: 26-06-2013
Review of gel dosimetry: a personal reflection
Publisher: IOP Publishing
Date: 2017
Dose resolution optimization of polymer gel dosimeters using different monomers
Publisher: IOP Publishing
Date: 18-09-2001
DOI: 10.1088/0031-9155/46/10/310
Abstract: Polymer gel dosimeters of different formulations were manufactured from different monomers of acrylamide, acrylic acid, methacrylic acid, 1-vinyl-2-pyrrolidinone, 2-hydroxyethyl methacrylate and 2-hydroxyethyl acrylate. Gelatin and agarose were used as the gelling agents and N,N'-methylene-bis-acrylamide was used as a co-monomer in each polymer gel dosimeter. The T2 dependence of each dosimeter was analysed using a model of fast exchange of magnetization. The influence of the half-dose and the apparent T2 of the polymer-proton pool on the dose resolution (Dpdelta) were examined. Comparisons are made with the commonly employed R2-dose sensitivity. Differences exist suggesting that experiments reported in the literature using what were thought to be more optimal dosimeters may not actually be so. Based on Dpdelta of each formulation, conclusions are drawn on the optimal formulation required for a specific range of absorbed doses. In addition, information about the extent of polymerization of the monomers used along with some characteristics of the polymer network formed are reported. The influence of the concentration of monomers and gelling agent was subsequently evaluated using a model of fast exchange of magnetization. Based on these calculations, further improvement in Dpdelta can be expected.
Is the PhD a qualification that is more or less standardised and accepted all over the world?
Publisher: Springer Science and Business Media LLC
Date: 26-10-2021
SU‐FF‐T‐181: An Investigation of Surface Dose Changes for Therapeutic Kilovoltage X‐Ray Beams with Underlying Lead Shielding
Publisher: Wiley
Date: 26-05-2005
DOI: 10.1118/1.1997862
Trends in Radiation Dosimetry: preliminary overview of active growth areas, research trends and hot topics from 2011-2015
Publisher: IOP Publishing
Date: 2017
Kilovoltage therapy is well and truly alive and needed in a modern radiotherapy centre
Publisher: Springer Science and Business Media LLC
Date: 25-04-2021
Optimised Motion Tracking for Positron Emission Tomography Studies of Brain Function in Awake Rats
Publisher: Public Library of Science (PLoS)
Date: 07-2011
Investigation of the relationship between linear attenuation coefficients and CT Hounsfield units using radionuclides for SPECT
Publisher: Elsevier BV
Date: 09-2008
DOI: 10.1016/J.APRADISO.2008.01.002
Abstract: This study has investigated the relationship between linear attenuation coefficients (mu) and Hounsfield units (HUs) for six materials covering the range of values found clinically. Narrow-beam mu values were measured by performing radionuclide transmission scans using (99m)Tc, (123)I, (131)I, (201)Tl and (111)In. The mu values were compared to published data. The relationships between mu and HU were determined. These relationships can be used to convert computed tomography (CT) images to mu-maps for single photon emission computed tomography (SPECT) attenuation correction.
Initial evaluation of a commercial EPID modified to a novel direct‐detection configuration for radiotherapy dosimetry
Publisher: Wiley
Date: 10-09-2008
DOI: 10.1118/1.2975156
Abstract: Electronic portal imaging devices (EPIDs) integrated with medical linear accelerators utilize an indirect-detection EPID configuration (ID-EPID). Amorphous silicon ID-EPIDs provide high quality low dose images for verification of radiotherapy treatments but they have limitations as dosimeters. The standard ID-EPID configuration includes a high atomic number phosphor scintillator screen, a 1 mm copper layer, and other nonwater equivalent materials covering the detector. This configuration leads to marked differences in the response of an ID-EPID compared to standard radiotherapy dosimeters such as ion chambers in water. In this study the phosphor and copper were removed from a standard commercial EPID to modify the configuration to a direct-detection EPID (DD-EPID). Using solid water as the buildup and backscatter for the detector, dosimetric measurements were performed on the DD-EPID and compared to standard dose-in-water data for 6 and 18 MV photons. The sensitivity of the DD-EPID was approximately eight times less than the ID-EPID but the signal was sufficient to produce accurate and reproducible beam profile measurements for open beams and an intensity-modulated beam. Due to the lower signal levels it was found necessary to ensure that the dark field correction (no radiation) DD-EPID signal was stable or updated frequently. The linearity of dose response was comparable to the ID-EPID but with a greater under-response at low doses. DD-EPID measurements of field size output factors and beam profiles at the depth of maximum dose (dmax), and tissue-maximum ratios between the depths of 0.5 and 10 cm, were in close agreement with dose in water measurements. At depths beyond dmax the DD-EPID showed a greater change in response to field size than ionisation chamber measurements and the beam penumbrae were broader compared to diode scans. The modified DD-EPID configuration studied here has the potential to improve the performance of EPIDs for dose verification of radiotherapy treatments.
Experimental investigation of the response of an amorphous silicon EPID to intensity modulated radiotherapy beams
Publisher: Wiley
Date: 24-10-2007
DOI: 10.1118/1.2789406
Abstract: The aim of this work was to experimentally determine the difference in response of an amorphous silicon (a-Si) electronic portal imaging device (EPID) to the open and multileaf collimator (MLC) transmitted beam components of intensity modulated radiation therapy (IMRT) beams. EPID dose response curves were measured for open and MLC transmitted (MLCtr) 10 x 10 cm2 beams at central axis and with off axis distance using a shifting field technique. The EPID signal was obtained by replacing the flood-field correction with a pixel sensitivity variation matrix correction. This signal, which includes energy-dependent response, was then compared to ion-chamber measurements. An EPID calibration method to remove the effect of beam energy variations on EPID response was developed for IMRT beams. This method uses the component of open and MLCtr fluence to an EPID pixel calculated from the MLC delivery file and applies separate radially dependent calibration factors for each component. The calibration procedure does not correct for scatter differences between ion chamber in water measurements and EPID response these must be accounted for separately with a kernel-based approach or similar method. The EPID response at central axis for the open beam was found to be 1.28 +/- 0.03 of the response for the MLCtr beam, with the ratio increasing to 1.39 at 12.5 cm off axis. The EPID response to MLCtr radiation did not change with off-axis distance. Filtering the beam with copper plates to reduce the beam energy difference between open and MLCtr beams was investigated however, these were not effective at reducing EPID response differences. The change in EPID response for uniform sliding window IMRT beams with MLCtr dose components from 0.3% to 69% was predicted to within 2.3% using the separate EPID response calibration factors for each dose component. A clinical IMRT image calibrated with this method differed by nearly 30% in high MLCtr regions from an image calibrated with an open beam calibration factor only. Accounting for the difference in EPID response to open and MLCtr radiation should improve IMRT dosimetry with a-Si EPIDs.
Evaluation of the water equivalence of solid phantoms using gamma ray transmission measurements
Publisher: Elsevier BV
Date: 08-2008
Simple methods for the correction of T2 maps of phantoms
Publisher: Wiley
Date: 15-11-2001
DOI: 10.1002/MRM.1308
Abstract: Two simple methodologies for correcting the errors in T2 maps for phantom measurements are presented they both give accurate MRI maps with a low coefficient of variation (CV). The rate correction method is based on an equation relating the true T2 (T2,t) and that determined experimentally (T2,exp) for homogenous phantoms. The response matrix method is a phenomenological analysis of the difference between T2,exp and T2,t, from which correction factors are computed for a range of T2 values and for every pixel of an image. The factors were obtained from phantoms filled with a homogeneous gelatin gel and having different T2,t values. The CV in homogeneous phantom measurements were reduced from 2.5-4.0% to approximately 0.6-2.0% for T2,t values ranging from 180-600 ms. Ex les are shown for the correction of T2 maps of phantoms filled with polymer dosimeter gel irradiated with photon beams from a linear accelerator. The methodologies presented can easily be implemented on a clinical MRI scanner.
An experimental investigation into the radiation field offset of a dynamic multileaf collimator
Publisher: IOP Publishing
Date: 09-10-2006
DOI: 10.1088/0031-9155/51/21/009
Abstract: In this study we investigate the characteristics of a rounded leaf end multileaf collimator (MLC) that is used for delivering intensity-modulated radiotherapy (IMRT) with a Varian linear accelerator. The rounded leaf end MLC design results in an offset between the radiation field edge (the physical leaf position) and the light field (the geometric leaf position). We call this the radiation field offset (RFO). The leaf position is calibrated to the leaf tip at the mid-leaf plane. There is an additional offset between the geometric leaf position and the projected leaf tip position that varies as a function of distance from the collimator central axis due to the MLC geometry. We call this the leaf position offset (LPO). There is a lack of consistency in the interpretation and implementation of the RFO and the LPO in the literature. We investigated the RFO and the LPO on Varian's 600 C/D and 21 EX linear accelerators. We used a combination of film and ion chamber measurements of static, segmental MLC (SMLC) and dynamic MLC (DMLC) fields to quantify the leaf offsets across the range of leaf positions. We were able to improve the dosimetry at large off-axis positions with minor adjustments to the vendor's LPO file. The RFO was determined to within 0.1 mm accuracy at the collimator central axis. The measured RFO value depends on whether the method is based on the radiation field edge position or on an integral dose measurement. The integral dose method results in an RFO that is approximately 0.2 mm greater than the radiation field edge method. The difference is due to the MLC penumbra shape. We propose a methodology for measuring and implementing MLC leaf offsets that is suitable for both SMLC and DMLC IMRT. In addition, we propose some definitions that more clearly describe the MLC leaf position for accurate IMRT dosimetry.
A dosimetric evaluation of water equivalent phantoms for kilovoltage x-ray beams
Publisher: IOP Publishing
Date: 19-10-2005
Ultrasound tomography imaging of radiation dose distributions in polymer gel dosimeters: Preliminary study
Publisher: Wiley
Date: 24-07-2003
DOI: 10.1118/1.1590751
Abstract: A novel imaging system for investigation of absorbed dose distributions in radiotherapy polymer gel dosimeters using ultrasound is introduced. A prototype transmission ultrasound computed tomography (UCT) imaging system is developed and evaluated. The imaging capabilities of the system are assessed through investigation of an irradiated polyacrylamide gel test phantom. Images based on transmitted signal litude and time of flight (TOF) of the ultrasonic signal through the phantom are reconstructed using a filtered backprojection technique. In general, the reconstruction of the square field in the TOF image was superior to the transmission image, however, transmission images displayed superior contrast to TOF images. The image quality achieved with this prototype system is promising and could be significantly enhanced through improvements, in particular through the development of more sophisticated experimental equipment. It is concluded that UCT is a viable technique for imaging absorbed dose distributions in polymer gel dosimeters and investigations are continuing to further improve the system.
A study of a normoxic polymer gel dosimeter comprising methacrylic acid, gelatin and tetrakis (hydroxymethyl) phosphonium chloride (MAGAT)
Publisher: Elsevier BV
Date: 10-2005
DOI: 10.1016/J.APRADISO.2005.03.014
Abstract: In this study, the response to ionsing radiation of the normoxic polymer gel dosimeter comprising tetrakis (hydroxymethyl) phosphonium chloride (THPC) with methacrylic acid (MAA) and gelatin, named MAGAT, has been investigated. Using magnetic resonance imaging (MRI), the R2-dose response or change in R2 (DeltaR2) is evaluated for different concentrations of the component chemicals: THPC, MAA, gelatin and hydroquinone (HQ). The formulation for which the MAGAT polymer gel dosimeter had a maximum response was determined, and the spatial and temporal stability for this formulation analyzed. It was found that the formulation that provided the greatest change in R2 was 10 mM THPC, 0-0.05 mM HQ, 6-7% gelatin and 4-6% MAA (evaluated one day post-irradiation). MAGAT polymer gel dosimeters comprising 10mM THPC, 0.05 mM HQ, 6-9% MAA and 4-6% gelatin have shown potential for use in radiation therapy dosimetry.
An evaluation of Genipin gel as a water equivalent dosimeter for megavoltage electron beams and kilovoltage x-ray beams
Publisher: IOP Publishing
Date: 11-2010
SU‐DD‐A2‐03: Can the Linear Quadratic (LQ) Model Predict the Biological Response of Cells to Simple Dose Heterogeneity for Single and Multiple Fraction Irradiation?
Publisher: Wiley
Date: 06-2010
DOI: 10.1118/1.3467990
Novel SLAM-based markerless motion tracking of conscious unrestrained rodents in PET
Publisher: IEEE
Date: 10-2012
Benchmarking of a motion sensing system for medical imaging and radiotherapy.
Publisher: IOP Publishing
Date: 30-09-2008
DOI: 10.1088/0031-9155/53/20/019
Abstract: We have tested the performance of an Optotrak Certus system, which optically tracks multiple markers, in both position and time. To do this, we have developed custom code which enables a range of testing protocols, and make this code available to the community. We find that the Certus' positional accuracy is very high, around 20 microm at a distance of 2.8 m. In contrast, we find that its timing accuracy is typically no better than around 5-10% for typical data rates, whether one is using an ethernet connection or a dedicated SCSI link from the system to a host computer. However, with our code we are able to attach very accurate timest s to the data frames, and in cases where regularly-spaced data are not an absolute requirement, this will be more than adequate.
A genipin-gelatin gel dosimeter for radiation processing
Publisher: Elsevier BV
Date: 08-2012
Radiological properties of normoxic polymer gel dosimeters
Publisher: Wiley
Date: 23-03-2005
DOI: 10.1118/1.1881812
Abstract: The radiological properties of the normoxic polymer gel dosimeters MAGIC, MAGAS, and MAGAT [methacrylic and ascorbic acid in gelatin initiated by copper methacrylic acid gelatine gel with ascorbic acid and methacrylic acid gelatine and tetrakis (hydroxymethyl) phosphonium chloride, respectively] have been investigated. The radiological water equivalence was determined by comparing the polymer gel macroscopic photon and electron interaction cross sections over the energy range from 10 keV to 20 MeV and by Monte Carlo modeling of depth doses. Normoxic polymer gel dosimeters have a high gelatine and monomer concentration and therefore mass density (kg m(-3)) up to 3.8% higher than water. This results in differences between the cross-section ratios of the normoxic polymer gels and water of up to 3% for the attenuation, energy absorption, and collision stopping power coefficient ratios through the Compton dominant energy range. The mass cross-section ratios were within 2% of water except for the mass attenuation and energy absorption coefficients ratios, which showed differences with water of up to 6% for energies less than 100 keV. Monte Carlo modeling was undertaken for the polymer gel dosimeters to model the electron and photon transport resulting from a 6 MV photon beam. The absolute percentage differences between gel and water were within 1% and the relative percentage differences were within 3.5%. The results show that the MAGAT gel formulation is the most radiological water equivalent of the normoxic polymer gel dosimeters investigated due to its lower mass density measurement compared with MAGAS and MAGIC gels.
The dose response of normoxic polymer gel dosimeters measured using X-ray CT
Publisher: British Institute of Radiology
Date: 07-2005
DOI: 10.1259/BJR/46029447
Abstract: X-ray CT was used to determine the dose response of normoxic polymer gel dosimeters. Normoxic polymer gel dosimeters were manufactured and irradiated up to 150 Gy. Up to 50 CT images were acquired on a Toshiba Aquilion Multislice CT scanner using protocols for 80 kV and 135 kV to determine dose response. HU-dose sensitivity, the linear regression of data for the HU versus dose for the linear part of the curve up to 60 Gy was 0.38+/-0.07 HU Gy(-1) for 135 kV and 0.37+/-0.01 HU Gy(-1) for 80 kV. Dose resolution was found to be < 1.3 Gy for an absorbed dose range up to 70 Gy for 135 kV, similar to that measured previously for polyacrylamide gel (PAG). Although the HU-dose sensitivity was lower than that previously measured for PAG gel dosimeters it had a greater range of absorbed dose indicating that normoxic polymer gel dosimeters have potential in CT gel dosimetry.
Comment on `A systematic review of the precision and accuracy of dose measurements in photon radiotherapy using polymer and Fricke MRI gel dosimetry'
Publisher: IOP Publishing
Date: 21-01-2003
Modelling of post-irradiation events in polymer gel dosimeters
Publisher: IOP Publishing
Date: 05-10-2001
DOI: 10.1088/0031-9155/46/11/305
Abstract: The nuclear magnetic resonance (NMR) spin-spin relaxation time (T2) is related to the radiation-dependent concentration of polymer formed in polymer gel dosimeters manufactured from monomers in an aqueous gelatin matrix. Changes in T2 with time post-irradiation have been reported in the literature but their nature is not fully understood. We investigated those changes with time after irradiation using FT-Raman spectroscopy and the precise determination of T2 at high magnetic field in a polymer gel dosimeter. A model of fast exchange of magnetization taking into account ongoing gelation and strengthening of the gelatin matrix as well as the polymerization of the monomers with time is presented. Published data on the changes of T2 in gelatin gels as a function of post-manufacture time are used and fitted closely by the model presented. The same set of parameters characterizing the variations of T2 in gelatin gels and the increasing concentration of polymer determined from FT-Raman spectroscopy are used successfully in the modelling of irradiated polymer gel dosimeters. Minimal variations in T2 in an irradiated PAG dosimeter are observed after 13 h.
Magnetization transfer imaging for polymer gel dosimetry
Publisher: IOP Publishing
Date: 21-05-2002
DOI: 10.1088/0031-9155/47/11/304
Abstract: Off-resonance RF pre-saturation was used to obtain contrast in MRI images of polymer gel dosimeters irradiated to doses up to 50 Gy. Two different polymer gel dosimeters composed of 2-hydroxyethyl-acrylate or methacrylic acid monomers mixed with N, N'-methylene-bisacrylamide (BIS), dispersed in an aqueous gelatin matrix were evaluated. Radiation-induced polymerization of the co-monomers generates a fast-relaxing insoluble polymer. Saturation of the polymer using off-resonance Gaussian RF pulses prior to a spin-echo readout with a short echo time leads to contrast that is dependent on the absorbed dose. This contrast is attributed to magnetization transfer (MT) between free water and the polymer, and direct saturation of water was found to be negligible under the prevailing experimental conditions. The usefulness of MT imaging was assessed by computing the dose resolution obtained with this technique. We found a low value of dose resolution over a wide range of doses could be obtained with a single experiment. This is an advantage over multiple spin echo (MSE) experiments using a single echo spacing where an optimal dose resolution is achieved over only very limited ranges of doses. The results suggest MT imaging protocols may be developed into a useful tool for polymer gel dosimetry.
Analysis of sample volume dependence of 125I in a radionuclide calibrator
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-1991
DOI: 10.1097/00006231-199105000-00009
Abstract: Results are presented showing the volume dependence of the measured activity of 125I in Capintec radionuclide calibrators. Errors of up to 76% were encountered for commonly used syringes and vials when the manufacturer's calibration factor was used. Calibration factors have been determined for syringes and vials which reduce errors to less than 2%.
Quantifying lung shunting during planning for radio-embolization
Publisher: IOP Publishing
Date: 31-05-2011
Head and neck field matching verification using three dimensional PAGAT polymer gel dosimetry
Publisher: IOP Publishing
Date: 12-2006
Citations are a good way to determine the quality of research
Publisher: Springer Science and Business Media LLC
Date: 09-11-2020
SU-EE-A2-02: Evaluation of Radiation Dosimeters for Kilovoltage X-Ray Beam Dosimetry
Publisher: Wiley
Date: 06-2007
DOI: 10.1118/1.2760371
Monte Carlo Simulation Dose Calculation for Intensity Modulated Radiosurgery
Publisher: KARGER
Date: 2010
DOI: 10.1159/000288721
Measuring facial swelling using three-dimensional imaging
Publisher: Informa UK Limited
Date: 1997
DOI: 10.3109/14639239709010888
Abstract: Requirements exist clinically for quantitative analysis of facial swelling. A quick and non-invasive measurement of facial volume is desirable. The acquisition of three-dimensional images, corresponding to spatial models of patients' facial surfaces, has been facilitated using a Spatial Vision System (SVS) developed by Thorn EMI Central Research Laboratories (UK). The SVS acquires four video images (two step pairs) and constructs a three-dimensional surface representation using stereo matching of spatial features acquired using 'speckled' illumination. Pre- and post-operative binary volumetric images are then spatially aligned using surface matching algorithms. Accuracy of registration is optimized using Match Volume Excavation. Segmentation of post-operative swelling is achieved by volume differencing in combination with morphological erosion. Volumetric quantification is achieved using a method of three-dimensional region growing, giving the number of connected voxels in the image volume from a user selected seed point. Accuracy of image acquisition has ben quantified by imaging a range of hemispherical phantoms of known volumes. The mean error in repeated measurement of volume was found to be within 3.5%. The perception of temporal changes in facial swelling is highly subjective. Further work is being undertaken to develop and Enhanced Reality visualization tool in which graphical swelling annotations are combined with real-time patient images.
Quantitative SPECT reconstruction using CT-derived corrections
Publisher: IOP Publishing
Date: 21-05-2008
DOI: 10.1088/0031-9155/53/12/002
Abstract: A method for achieving quantitative single-photon emission computed tomography (SPECT) based upon corrections derived from x-ray computed tomography (CT) data is presented. A CT-derived attenuation map is used to perform transmission-dependent scatter correction (TDSC) in conjunction with non-uniform attenuation correction. The original CT data are also utilized to correct for partial volume effects in small volumes of interest. The accuracy of the quantitative technique has been evaluated with phantom experiments and clinical lung ventilation erfusion SPECT/CT studies. A comparison of calculated values with the known total activities and concentrations in a mixed-material cylindrical phantom, and in liver and cardiac inserts within an anthropomorphic torso phantom, produced accurate results. The total activity in corrected ventilation-subtracted perfusion images was compared to the calibrated injected dose of [(99m)Tc]-MAA (macro-aggregated albumin). The average difference over 12 studies between the known and calculated activities was found to be -1%, with a range of +/-7%.
University rankings and medical physics
Publisher: Springer Science and Business Media LLC
Date: 12-2013
Attenuation of Diagnostic Energy Photons by Polymer Gel Dosimeters
Publisher: IOP Publishing
Date: 12-11-2002
DOI: 10.1088/0031-9155/47/23/310
Abstract: Post-irradiation changes in the linear attenuation coefficient, mu, of polymer gel dosimeters give rise to a change which can be measured with x-ray computed tomography. Polymer gel dosimeters were manufactured consisting of 3% (by weight) acrylamide and 3% N,N'-methylene-bis-acrylamide comonomers dissolved in aqueous gelatin (5% gelatin by total weight and 89% de-ionized distilled water). Mu was measured in a collimated radiation beam of photons from an 241Am source. Density, rho, of polymer gel dosimeters was measured using volumetric flasks with capillary stoppers. The measured post-irradiation data of mu was plotted against the data of rho for different batches, and linear least squares fits gave r2 values of 0.99605 and 0.99953, with P values of less than 0.001. This confirms that the post-irradiation change in mu is proportional to that of rho. The change in rho implies a change in volume regardless of the evaluation modality of the polymer gel dosimeter.
Photometric calibration of a radiochromic gel dosimeter
Publisher: IOP Publishing
Date: 26-06-2013
SU‐GG‐T‐282: Investigation of Optical Artifacts in a Complex Light‐Scattering Gel Phantom for Optical CT Polymer Gel Dosimetry
Publisher: Wiley
Date: 06-2008
DOI: 10.1118/1.2962034
Investigation of the PAGAT polymer gel dosimeter using magnetic resonance imaging
Publisher: IOP Publishing
Date: 02-08-2005
DOI: 10.1088/0031-9155/50/16/015
Abstract: Investigation of the normoxic PAGAT polymer gel dosimeter has been undertaken. The concentrations of the chemical components of the gel were varied and its response to ionizing radiation evaluated. Using MRI, the formulation to give the maximum change in the transverse relaxation rate R2 was determined to be 4.5% N, N'-methylene-bis-acrylamide (bis), 4.5% acrylamide (AA), 5% gelatine, 5 mM tetrakis (hydroxymethyl) phosphonium chloride (THPC), 0.01 mM hydroquinone (HQ) and 86% H2O. The optimal post-manufacture irradiation and post-irradiation imaging times were both determined to be 12 h. The R2-dose response was linear up to 7 Gy with R2-dose sensitivities of (0.183 +/- 0.005) s(-1) Gy(-1), (0.182 +/- 0.005) s(-1) Gy(-1) and (0.192 +/- 0.005) s(-1) Gy(-1) when imaged at 12 h, 7 days and 24 days post-irradiation, respectively. The R2-dose sensitivities were within the range of previously published values for the hypoxic PAG formulations. For the imaging parameters used in this study the optimum dose resolution was achieved for low doses. The normalized R2 edge response showed a high degree of spatial stability over a 24 day period. This study has shown that the normoxic PAGAT polymer gel has the properties of a dosimetric tool, which can be used in clinical radiotherapy. The PAGAT polymer gel has been shown to have similar qualities to the PAG polymer gel, while offering the significant advantage of simplification of the manufacturing procedure.
An evaluation of ionization chambers for the relative dosimetry of kilovoltage x‐ray beams
Publisher: Wiley
Date: 12-08-2009
DOI: 10.1118/1.3183820
Abstract: In this work, the authors have evaluated ten different ionization chambers for the relative dosimetry of kilovoltage x-ray beams in the energy range of 50-280 kVp. Percentage depth doses in water and relative detector response (in Solid Water and in air) were measured for each of the x-ray beams studied using a number of chambers. Measured depth dose data were compared with Monte Carlo calculated depth doses using the EGSnrc Monte Carlo package and the BEAMnrc user code. The accuracy of the phase space files generated by BEAMnrc was verified by calculating the half-value layer and comparing with the measured half-value layer of each x-ray beam. The results indicate that the Advanced Markus, Markus, NACP, and Roos parallel plate ionization chambers were suitable for the measurement of depth dose data in this beam quality range with an uncertainty of less than 3%, including in the regions close to the water surface. While the relative detector response of the Farmer and scanning thimble chambers exhibited a better energy response, they were not suitable for depth dose measurements in the first 5 mm below the water surface with differences of up to 12% in the surface dose measurement for the 50 kVp x-ray beam. These differences were due to dose artifacts generated by the chamber size and the dose gradient. However, at depths greater than 5 mm, the Farmer and thimble scanning chambers gave uncertainties of less than 3% for the depth dose measurements for all beam energies. The PTW PinPoint 31006 chamber was found to give varying dose differences of up to 8% depending on the x-ray beam energy this was attributed to the steel central electrode. The authors recommend that one of the parallel plate ionization chambers investigated be used to determine depth dose data for kilovoltage x-ray beams in the energy range studied and give correct dose information close to the surface and at depth in the water phantom.
SU-GG-T-284: Modelling the Effect of Optical Pathlength On Light Scattering Artefacts in Optical CT for Polymer Gel Dosimetry
Publisher: Wiley
Date: 06-2008
DOI: 10.1118/1.2962036
CT-based quantitative SPECT for the radionuclide 201Tl: experimental validation and a standardized uptake value for brain tumour patients
Publisher: E-MED LTD
Date: 2012
Verification of a non-diffusing gel dosimeter
Publisher: IOP Publishing
Date: 26-06-2013
Citations, Open Access and University Rankings
Publisher: IGI Global
Date: 2017
DOI: 10.4018/978-1-5225-0819-9.CH007
Abstract: The citation impact of research articles contributes to the assessment of the research performance of universities in some international university ranking systems either as the number of citations per paper, number of citations per faculty, total number of citations, number of highly cited papers or percentage of highly cited papers. Publishing research articles in Open Access (OA) journals has the potential for increasing the citation impact of research articles and in so doing improve an institutions position in university rankings. This chapter reviews the evidence for an increase in citations through publishing in Open Access publications.
Computer simulations can replace in-vivo experiments for implantable medical devices
Publisher: Springer Science and Business Media LLC
Date: 08-02-2021
The push-pull dosimeter: When two pigments are better than one
Publisher: IOP Publishing
Date: 11-2010
Absolute Activity Determination of <formula formulatype=inline><tex>$^{198}$</tex> </formula>Au Solid Source Using <formula formulatype=inline><tex>$4\pi\beta$&
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2007
Famous medical physicists often get more credit for discoveries due to their fame than less prominent scientists who may have contributed as much or earlier to these developments
Publisher: Wiley
Date: 15-02-2017
DOI: 10.1002/MP.12089
Dose resolution in radiotherapy polymer gel dosimetry: effect of echo spacing in MRI pulse sequence
Publisher: IOP Publishing
Date: 19-04-2001
SU-GG-T-21: Evaluation of HDR Brachytherapy Dose Distributions Using PRESAGE Three-Dimensional Polymer Dosimeter and Optical CT Readout
Publisher: Wiley
Date: 06-2008
DOI: 10.1118/1.2961771
Water equivalence of micelle gels for x-ray beams
Publisher: IOP Publishing
Date: 26-06-2013
Water equivalency evaluation of PRESAGE® dosimeters for dosimetry of Cs-137 and Ir-192 brachytherapy sources
Publisher: IOP Publishing
Date: 11-2010
In the future, ultrasound guidance in radiotherapy will become a clinical standard
Publisher: Springer Science and Business Media LLC
Date: 17-05-2021
Development and optimization of a 2-hydroxyethylacrylate MRI polymer gel dosimeter
Publisher: IOP Publishing
Date: 05-01-2004
DOI: 10.1088/0031-9155/49/2/004
Abstract: In this study, radiation induced changes in a polymer gel dosimeter manufactured using 2-hydroxyethylacrylate (HEA) and N,N'-methylene-bisacrylamide (BIS) were investigated using magnetic resonance imaging (MRI) and FT-Raman spectroscopy. The variation in magnetic resonance relaxation time (T2) with absorbed dose was modelled assuming fast exchange of magnetization. Overall good agreement between the model and experimental data was obtained. However, comparison with FT-Raman data suggests that not all the protons attached to the polymer contribute to the relaxation process. Furthermore, for certain compositions improved agreement with experimental data was achieved when a lower fraction of polymer protons available for exchange with water was assumed in the low dose region. This indicates that the T2 value is influenced by the composition and topology of the formed polymer, which may vary with absorbed dose. The concept of percentage dose resolution (Dp delta, %) was introduced to enable optimization of gel compositions for use in relative dosimetry applications. This concept was applied to demonstrate the effects of varying the gelatine concentration, the total fraction of monomer/crosslinker (%T) and the relative fraction of crosslinker (%C) on gel performance in HEA gels as well as compare the performance of HEA and a standard polyacrylamide gel (PAG). The percentage dose resolution was improved for all HEA gels compared to the PAG dosimeter containing 3% acrylamide and 3% BIS. Increasing the total concentration of monomer was shown to have the largest single effect. In the range of doses of interest for clinical radiation therapy, Dp delta, % for the optimal HEA gel (4% HEA, 4% BIS) was lower than 2.3%, compared to 3.8% for the PAG dosimeter.
Sensitivity and stability of the Fricke–gelatin–xylenol orange gel dosimeter
Publisher: Elsevier BV
Date: 06-2008
Uncertainty analysis in polymer gel dosimetry
Publisher: IOP Publishing
Date: 20-10-1999
DOI: 10.1088/0031-9155/44/11/402
Abstract: Verification of advanced radiotherapy treatment modalities requires measurement of three-dimensional absorbed dose distributions with high spatial resolution and precision. Polymer gel dosimeters combined with magnetic resonance imaging may be able to fulfil this requirement. However, verification requires that the uncertainty in the dosimeter is well known. One method of estimating the overall uncertainty in polymer gel dosimeters involves the propagation of the uncertainty in the R2 (nuclear magnetic resonance relaxation rate) map and the uncertainties in the calibration data. This work shows that using this method with current data suggests that the lowest uncertainty currently obtainable is about 3% at 8 Gy and 7% at 2 Gy. Furthermore, the most significant reductions in overall uncertainty will be achieved by reducing the noise in the R2 map.
Radiological characterization and water equivalency of genipin gel for x-ray and electron beam dosimetry
Publisher: IOP Publishing
Date: 06-07-2011
DOI: 10.1088/0031-9155/56/15/004
Abstract: The genipin radiochromic gel offers enormous potential as a three-dimensional dosimeter in advanced radiotherapy techniques. We have used several methods (including Monte Carlo simulation), to investigate the water equivalency of genipin gel by characterizing its radiological properties, including mass and electron densities, photon interaction cross sections, mass energy absorption coefficient, effective atomic number, collisional, radiative and total mass stopping powers and electron mass scattering power. Depth doses were also calculated for clinical kilovoltage and megavoltage x-ray beams as well as megavoltage electron beams. The mass density, electron density and effective atomic number of genipin were found to differ from water by less than 2%. For energies below 150 keV, photoelectric absorption cross sections are more than 3% higher than water due to the strong dependence on atomic number. Compton scattering and pair production interaction cross sections for genipin gel differ from water by less than 1%. The mass energy absorption coefficient is approximately 3% higher than water for energies <60 keV due to the dominance of photoelectric absorption in this energy range. The electron mass stopping power and mass scattering power differ from water by approximately 0.3%. X-ray depth dose curves for genipin gel agree to within 1% with those for water. Our results demonstrate that genipin gel can be considered water equivalent for kilovoltage and megavoltage x-ray beam dosimetry. For megavoltage electron beam dosimetry, however, our results suggest that a correction factor may be needed to convert measured dose in genipin gel to that of water, since differences in some radiological properties of up to 3% compared to water are observed. Our results indicate that genipin gel exhibits greater water equivalency than polymer gels and PRESAGE formulations.
Experimental determination of the diffusion coefficient in two-dimensions in ferrous sulphate gels using the finite element method
Publisher: Springer Science and Business Media LLC
Date: 03-2001
DOI: 10.1007/BF03178282
A preliminary study of the novel application of normoxic polymer gel dosimeters for the measurement of CTDI on diagnostic x‐ray CT scanners
Publisher: Wiley
Date: 17-05-2005
DOI: 10.1118/1.1925181
Abstract: Computer tomography dose index (CTDI) is a measurement undertaken during acceptance testing and subsequent quality assurance measurements of diagnostic x-ray CT scanners for the determination of patient dose. Normoxic polymer gel dosimeters have been used for the first time to measure dose and subsequently CTDI during acceptance testing of a CT scanner and compared with the conventional ionization chamber measurement for a range of imaging protocols. The normoxic polymer gel dosimeter was additionally used to simultaneously determine slice-width dose profiles and CTDI in the transaxial plane, the measurements of which are usually determined with thermoluminescent dosimetry or film. The resulting CTDI for all slice widths calculated from the normoxic polymer gel dosimeter were within corresponding ionization chamber CTDI values. Slice-width dose-profiles full-width half-maximum values from the normoxic polymer gel dosimeter were compared to the slice sensitivity profiles and were within the tolerances of the manufacturer. Normoxic polymer gel dosimeters have been shown to be a useful device for determining CTDI and dose distributions for CT equipment, and provide additional information not possible with just the use of an ionization chamber.
An Australian secondary standard dosimetry laboratory participation in IAEA postal dose audits
Publisher: Springer Science and Business Media LLC
Date: 12-02-2013
DOI: 10.1007/S13246-013-0184-2
Abstract: For over 30 years, the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO) have jointly monitored activities of secondary standard dosimetry laboratories (SSDLs) through postal dose audits with the aim of achieving consistency in dosimetry throughout the world. The Australian Nuclear Science and Technology Organisation (ANSTO) maintains an SSDL and is a member of the IAEA/WHO SSDL Network. Postal dose audit results at this Australian SSDL from 2001 to 2011 demonstrate the consistency of absorbed dose to water measurements, underpinned by the primary standard maintained at the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA).
Should ACPSEM develop its own position papers or just adopt those of the AAPM?
Publisher: Springer Science and Business Media LLC
Date: 21-07-2020
Direct-detection EPID dosimetry: investigation of a potential clinical configuration for IMRT verification
Publisher: IOP Publishing
Date: 11-11-2009
DOI: 10.1088/0031-9155/54/23/008
Abstract: The routine use of electronic portal imaging devices (EPIDs) as dosimeters for radiotherapy quality assurance is complicated by the non-water equivalence of the EPID's dose response. A commercial EPID modified to a direct-detection configuration was previously demonstrated to provide water-equivalent dose response with d(max) solid water build-up and 10 cm solid water backscatter. Clinical implementation of the direct EPID (dEPID) requires a design that maintains the water-equivalent dose response, can be incorporated onto existing EPID support arms and maintains sufficient image quality for clinical imaging. This study investigated the dEPID dose response with different configurations of build-up and backscatter using varying thickness of solid water and copper. Field size output factors and beam profiles measured with the dEPID were compared with ionization chamber measurements of dose in water for both 6 MV and 18 MV. The dEPID configured with d(max) solid water build-up and no backscatter (except for the support arm) was within 1.5% of dose in water data for both energies. The dEPID was maintained in this configuration for clinical dosimetry and image quality studies. Close agreement between the dEPID and treatment planning system was obtained for an IMRT field with 98.4% of pixels within the field meeting a gamma criterion of 3% and 3 mm. The reduced sensitivity of the dEPID resulted in a poorer image quality based on quantitative (contrast-to-noise ratio) and qualitative (anthropomorphic phantom) studies. However, clinically useful images were obtained with the dEPID using typical treatment field doses. The dEPID is a water-equivalent dosimeter that can be implemented with minimal modifications to the standard commercial EPID design. The proposed dEPID design greatly simplifies the verification of IMRT dose delivery.
Investigation and analysis of ferrous sulfate polyvinyl alcohol (PVA) gel dosimeter
Publisher: IOP Publishing
Date: 12-11-2002
DOI: 10.1088/0031-9155/47/23/309
Abstract: Ferrous sulfate (Fe(SO4)2) PVA gels were investigated for a range of absorbed doses up to 20 Gy using both magnetic resonance imaging (MRI) and spectrophotometry to determine R1 and optical density (OD) dose responses and G values. It was found that R1- and OD-dose sensitivities increased with O2 saturation or by the introduction of a freeze-thaw cycle during preparation of the PVA gel. The storage temperature of the Fe(SO4)2 PVA gel at -18 degrees C increased R1-dose sensitivity above that of gels stored at 5 degrees C. The addition of sucrose to the formulation was found to result in the largest increase in both R1- and OD-dose sensitivities. Fe(SO4)2 PVA gel with and without the addition of xylenol orange was demonstrated to have a G value of approximately 20 ions/100 eV and with sucrose approximately 24 ions/100 eV.
The quenching effect in PRESAGE® dosimetry of proton beams: Is an empirical correction feasible?
Publisher: IOP Publishing
Date: 12-01-2015
Optimization of multiple spin$ndash$echo sequences for 3D polymer gel dosimetry
Publisher: IOP Publishing
Date: 06-08-2002
DOI: 10.1088/0031-9155/47/17/306
Abstract: The overall performance of polymer gel dosimeters for three-dimensional radiation dosimetry is determined by the temporal and spatial stability of the gels, dose sensitivity and image quality with respect to both systematic and stochastic deviations. The dose resolution (D(p)delta) is determined by the dose sensitivity and the signal-to-noise ratio (SNR) in the dose images. The dose sensitivity can be altered by changing the chemical composition of the polymer gel. The SNR is determined by the scanner and the imaging sequence. In the dose verification of conformal radiotherapy treatments the chosen number of slices may reach a number of 10-20. For these experiments, to obtain a sufficient SNR within a reasonable measurement time using a certain MR scanner, the imaging sequence should be optimized. A few other studies have emphasized the importance of optimizing the imaging sequence with respect to dose resolution (D(p)delta) or SNR but do not give quantitative values for the optimal sequence parameters for scanning a polymer gel dosimeter in three dimensions. In this paper, it is proved that a multiple spin-echo sequence is preferable to a single spin-echo sequence. It is also shown that when using a multiple spin-echo sequence it is not the inter-echo time that should be optimized but the number of echoes. An algebraical expression is derived for the dose resolution in terms of sequence parameters. A mathematical formalism and look-up tables are provided that can be used to optimize both a single and a slice-selective multiple spin-echo sequence to acquire a set of dose images at various locations. The use of the optimization protocol is illustrated by some ex les. The optimization protocol enables the user to derive the optimal sequence parameters to acquire a set of dose maps obtained by quantitative T2 imaging for each polymer gel dosimeter within the shortest time possible.
In the future simulations will replace clinical trials
Publisher: Springer Science and Business Media LLC
Date: 12-2021
Historical overview of the development of gel dosimetry: a personal perspective
Publisher: IOP Publishing
Date: 12-2006
Intercomparison of ionisation chamber measurements from 125I seeds
Publisher: Elsevier BV
Date: 05-2007
DOI: 10.1016/J.APRADISO.2006.12.002
Abstract: The reference air kerma rates of a set of in idual (125)I seeds were calculated from current measurements of a calibrated re-entrant ionisation chamber. Single seeds were distributed to seven Australian brachytherapy centres for the same measurement with the user's instrumentation. Results are expressed as the ratio of the reference air kerma rate measured by the Australian Nuclear Science & Technology Organisation (ANSTO) to the reference air kerma rate measured at the centre. The intercomparison ratios of all participants were within +/-5% of unity.
Historical overview of the development of gel dosimetry: Another personal perspective
Publisher: IOP Publishing
Date: 05-2009
SU‐GG‐T‐130: A Software Tool for IMRT and EPI Dosimetry Research
Publisher: Wiley
Date: 06-2008
DOI: 10.1118/1.2961882
An increase in retractions of research publications is an issue for Medical Physics
Publisher: Wiley
Date: 20-11-2020
DOI: 10.1002/MP.14550
Temperature dependence on the dose response of the Fricke–gelatin–xylenol orange gel dosimeter
Publisher: Elsevier BV
Date: 05-2010
Dose resolution in gel dosimetry: Effect of uncertainty in the calibration function
Publisher: IOP Publishing
Date: 05-05-2004
DOI: 10.1088/0031-9155/49/10/N02
Abstract: Dose resolution, DdeltaP, is becoming a common method for characterizing the performance of a gel dosimeter. In this note we examine how the goodness of fit of the calibration function affects DdeltaP and show that its inclusion in the calculation of DdeltaP is essential to avoid overestimating the performance of the gel.
Radiation Dose Distribution in Polymer Gels by Raman Spectroscopy
Publisher: SAGE Publications
Date: 2003
DOI: 10.1366/000370203321165205
Abstract: The Raman spectroscopy of polymer gel dosimeters has been investigated with a view to developing a novel dosimetry technique that is capable of determining radiation dose within a micrometer of spatial resolution. The polymer gel dosimeter, known as the PAG dosimeter, is typically made up of acrylamide, N,N′-methylene-bis-acrylamide, gelatin, and water. A polyacrylamide network within the gelatin matrix forms in response to an absorbed dose. The loss of monomers may be monitored by corresponding changes to the Raman spectrum. Principal component analysis offers a simple method of quantifying the absorbed radiation dose from the Raman spectrum of the polymer gel. The background luminescence in the spectrum increased significantly with dose and is shown to originate in the glass of the s le vial. The competing effects of elastic scatter, which increases with dose due to the formation of polymer, and s le absorption were quantified and found to introduce errors of up to 5% under certain conditions. Raman spectra as a function of distance from the air–surface interface have been measured for s les that were subjected to doses delivered by a clinical linear accelerator. The depth dose profile thus obtained compared favorably with “gold standard” ion-chamber measurements.
Water equivalence evaluation of PRESAGE® formulations for megavoltage electron beams: A Monte Carlo study
Publisher: Springer Science and Business Media LLC
Date: 12-2012
DOI: 10.1007/S13246-012-0174-9
Abstract: To investigate the radiological water equivalency of three different formulations of the radiochromic, polyurethane based dosimeter PRESAGE(®) for three dimensional (3D) dosimetry of electron beams. The EGSnrc/BEAMnrc Monte Carlo package was used to model 6-20 MeV electron beams and calculate the corresponding doses delivered in the three different PRESAGE(®) formulations and water. The depth of 50 % dose and practical range of electron beams were determined from the depth dose calculations and scaling factors were calculated for these electron beams. In the buildup region, a 1.0 % difference in dose was found for all PRESAGE(®) formulations relative to water for 6 and 9 MeV electron beams while the difference was negligible for the higher energy electron beams. Beyond the buildup region (at a depth range of 22-26 mm for the 6 MeV beam and 38 mm for the 9 MeV beam), the discrepancy from water was found to be 5.0 % for the PRESAGE(®) formulations with lower halogen content than the original formulation, which was found to have a discrepancy of up to 14 % relative to water. For a 16 MeV electron beam, the dose discrepancy from water increases and reaches about 7.0 % at 70 mm depth for the lower halogen content PRESAGE(®) formulations and 20 % at 66 mm depth for the original formulation. For the 20 MeV electron beam, the discrepancy drops to 6.0 % at 90 mm depth for the lower halogen content formulations and 18 % at 85 mm depth for the original formulation. For the lower halogen content PRESAGE(®), the depth of 50 % dose and practical range of electrons differ from water by up to 3.0 %, while the range of differences from water is between 6.5 and 8.0 % for the original PRESAGE(®) formulation. The water equivalent depth scaling factor required for the original formulation of PRESAGE(®) was determined to be 1.07-1.08, which is larger than that determined for the lower halogen content formulations (1.03) over the entire beam energy range of electrons. All three of the PRESAGE(®) formulations studied require a depth scaling factor to convert depth in PRESAGE(®) to water equivalent depth for megavoltage electron beam dosimetry. Compared to the original PRESAGE(®) formulation, the lower halogen content formulations require a significantly smaller scaling factor and are thus recommended over the original PRESAGE(®) formulation for electron beam dosimetry.
An experimental study of the dose response of polymer gel dosimeters imaged with x-ray computed tomography
Publisher: IOP Publishing
Date: 19-10-2001
DOI: 10.1088/0031-9155/46/11/312
Abstract: Changes in the linear attenuation coefficient of polymer gel dosimeters post-irradiation enable the imaging of dose distributions by x-ray computed tomography (CT). Various compositions of polymer gel dosimeters manufactured from acrylamide (AA), and N,N'-methylene-bis-acrylamide (BIS) comonomers and gelatin or agarose gelling agents were investigated. This work shows that increasing the comonomer concentration increases the CT-dose sensitivity of the polymer gel dosimeter. This can be further increased by replacing gelatin with agarose. Varying the gelatin concentration however does not significantly change the CT-dose sensitivity. Among the compositions studied, dose resolution (D(delta)95%) was found to be optimal for polymer gel dosimeters comprising 5% gelatin, 3% AA, 3% BIS and 89% water.
Ultrasound evaluation of polymer gel dosimeters
Publisher: IOP Publishing
Date: 19-04-2002
DOI: 10.1088/0031-9155/47/9/302
Abstract: A new method for the evaluation of radiotherapy 3D polymer gel dosimeters has been developed using ultrasound to assess the significant structural changes that occur following irradiation of the dosimeters. The ultrasonic parameters of acoustic speed of propagation, attenuation and transmitted signal intensity were measured as a function of absorbed radiation dose. The dose sensitivities for each parameter were determined as 1.8 x 10(-4) s m(-1) Gy(-1), 3.9 dB m(-1) Gy(-1) and 3.2 V(-1) Gy(-1) respectively. All parameters displayed a strong variation with absorbed dose that continued beyond absorbed doses of 15 Gy. The ultrasonic measurements demonstrated a significantly larger dynamic range in dose response curves than that achieved with previously published magnetic resonance imaging (MRI) dose response data. It is concluded that ultrasound shows great potential as a technique for the evaluation of polymer gel dosimeters.
Benchmarking of a motion sensing system for medical imaging and radiotherapy
Publisher: IEEE
Date: 2007
Radiation treatment dose optimisation using Poisson tumour control probability parameters
Publisher: IOP Publishing
Date: 24-03-2014
13C-NMR,1H-NMR, and FT-Raman study of radiation-induced modifications in radiation dosimetry polymer gels
Publisher: Wiley
Date: 2000
DOI: 10.1002/1097-4628(20010228)79:9<1572::AID-APP50>3.0.CO;2-B
Experimental procedure for the manufacture and calibration of polyacrylamide gel (PAG) for magnetic resonance imaging (MRI) radiation dosimetry
Publisher: IOP Publishing
Date: 03-1998
DOI: 10.1088/0031-9155/43/3/019
Abstract: A simple methodology for the manufacture and calibration of polyacrylamide gel (PAG) for magnetic resonance imaging (MRI) radiation dosimetry is presented to enable in iduals to undertake such work in a routine clinical environment. S les of PAG were irradiated using a linear accelerator and imaged using a 0.5 T (22 MHz) Philips Gyroscan MRI scanner. The mean spin-lattice relaxation rate was measured using a 'turbo-mixed' sequence, consisting of a series of 90 degrees pulses, each followed by acquisition of a train of spin echoes. The mean sensitivity for five different batches of PAG in the range up to 10 Gy was calculated to be 0.0285 s-1 Gy-1 for the mean spin-lattice relaxation rate with a percentage standard deviation of 1.25%. The overall reproducibility between batches was calculated to be 2.69%. This methodology, which introduces the novel use of pre-filled nitrogen vials for calibration, has been used to develop techniques for filling anatomically shaped anthropomorphic phantoms.
A method for determining the diffusion coefficient in Fe(II/III) radiation dosimetry gels using finite elements
Publisher: IOP Publishing
Date: 09-1996
DOI: 10.1088/0031-9155/41/9/013
Abstract: Magnetic resonance imaging (MRI) may be used to image three-dimensional dose distributions of ionizing radiation in tissue equivalent gels infused with ferrous sulphate solutions, commonly known as Fricke gels. In this technique, ferrous (Fe2+) ions are oxidized to ferric (Fe3+) ions by free radicals produced by ionizing radiation. A limitation on this technique is the diffusion of ferric (Fe3+) ions in the gel. A method is presented for evaluating the diffusion coefficient in Fricke gels. Finite elements are used to model variations of the concentration in space, coupled with an analytical scheme to integrate the resulting system of equations through time. This method may be used for problems with one, two or three space dimensions and with arbitrary initial and boundary conditions. Results are presented for one- and two-dimensional data.
Investigation of the NMR relaxation rate dose-response of a ceric sulphate dosimeter
Publisher: Elsevier BV
Date: 06-2002
DOI: 10.1016/S0969-8043(01)00252-4
Abstract: The relationship between the radiation absorbed dose and the NMR longitudinal and transversal relaxation rates, R1 and R2, respectively, of a ceric sulphate dosimeter was examined. By adding copper sulphate, the R1 and R2 dose-responses were found to be linear up to 60 kGy with dose sensitivities of 13 x 10(-6) and 15 x 10(-6) s(-1) Gy(-1) , respectively. There is thus the potential for a three-dimensional ceric dosimeter for high dose applications, provided a suitable gelling substance is used.
Related Organisations
Related Funding Activities
Linkage Infrastructure, Equipment And Facilities - Grant ID: LE120100006
Start Date: 2012
End Date: 12-2017
Amount: $600,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP1094173
Start Date: 02-2010
End Date: 12-2013
Amount: $180,000.00
Funder: Australian Research Council
View Funded Activity