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Hayes C, King RB, Hounsell AR, Agnew CE. Impact of target degradation on the 6FFF output of a Varian TrueBeam Linac. Phys Med 2024; 124:103424. [PMID: 39002424 DOI: 10.1016/j.ejmp.2024.103424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 06/07/2024] [Accepted: 06/29/2024] [Indexed: 07/15/2024] Open
Abstract
The dosimetric output of a 6FFF beam, produced from a Varian TrueBeam linac exhibited an unexpected downward trend over time that was contrary to well-established expectations. To elucidate the cause of this uncharacteristic trend, a review of the linac's quality control results over its lifetime was performed, including, constancy checks of the dosimetric output, beam energy, flatness and symmetry, and percentage depth dose characteristics. These results were supplemented with a comprehensive series of measurements including flatness and symmetry measurements with a 1D-diode array, high-resolution measurements of the photon beam's build-up region with a parallel-plate chamber and measurement of the beam's output as a function of the x-ray target position. The review of the linac's QC results and supplemental tests identified no deviations in the linac's performance from its commissioning and baseline measurements. However, the 6FFF beam output exhibited a significant dependence on the target location relative to its default position, increasing by 5.43 % with a 0.5 mm target translation, indicating that target degradation was the cause of the atypical output trend. The change in output behaviour was believed to be the result of primary electrons escaping the degraded target and interacting with the linac's monitor chamber. Replacement of the x-ray target caused the 6FFF output to realign with expected trends. Target degradation was uncovered due to a robust quality control trending database and awareness of typical output behaviour. These results demonstrate the importance of data trending to identify component failure and provide centres with knowledge to recognise this potential fault.
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Affiliation(s)
- Chris Hayes
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, Northern Ireland, United Kingdom.
| | - Raymond B King
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, Northern Ireland, United Kingdom
| | - Alan R Hounsell
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, Northern Ireland, United Kingdom; Patrick G Johnston Centre for Cancer Research, Queen's University Belfast, Jubilee Road, Belfast, Northern Ireland, United Kingdom
| | - Christina E Agnew
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, Northern Ireland, United Kingdom
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Ocampo J, Heyes G, Dehghani H, Scanlon T, Jolly S, Gibson A. Determination of output factor for CyberKnife using scintillation dosimetry and deep learning. Phys Med Biol 2024; 69:025024. [PMID: 38181420 DOI: 10.1088/1361-6560/ad1b69] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 01/05/2024] [Indexed: 01/07/2024]
Abstract
Objective. Small-field dosimetry is an ongoing challenge in radiotherapy quality assurance (QA) especially for radiosurgery systems such as CyberKnifeTM. The objective of this work is to demonstrate the use of a plastic scintillator imaged with a commercial camera to measure the output factor of a CyberKnife system. The output factor describes the dose on the central axis as a function of collimator size, and is a fundamental part of CyberKnife QA and integral to the data used in the treatment planning system.Approach. A self-contained device consisting of a solid plastic scintillator and a camera was build in a portable Pelicase. Photographs were analysed using classical methods and with convolutional neural networks (CNN) to predict beam parameters which were then compared to measurements.Main results. Initial results using classical image processing to determine standard QA parameters such as percentage depth dose (PDD) were unsuccessful, with 34% of points failing to meet the Gamma criterion (which measures the distance between corresponding points and the relative difference in dose) of 2 mm/2%. However, when images were processed using a CNN trained on simulated data and a green scintillator sheet, 92% of PDD curves agreed with measurements with a microdiamond detector to within 2 mm/2% and 78% to 1%/1 mm. The mean difference between the output factors measured using this system and a microdiamond detector was 1.1%. Confidence in the results was enhanced by using the algorithm to predict the known collimator sizes from the photographs which it was able to do with an accuracy of less than 1 mm.Significance. With refinement, a full output factor curve could be measured in less than an hour, offering a new approach for rapid, convenient small-field dosimetry.
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Affiliation(s)
- Jeremy Ocampo
- UCL Physics and Astronomy, London, WC1E 6BT, United Kingdom
| | - Geoff Heyes
- Radiotherapy Physics, University Hospitals Birmingham NHS Foundation Trust, Birmingham B15 2TH, United Kingdom
| | - Hamid Dehghani
- School of Computer Science, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Tim Scanlon
- UCL Physics and Astronomy, London, WC1E 6BT, United Kingdom
| | - Simon Jolly
- UCL Physics and Astronomy, London, WC1E 6BT, United Kingdom
| | - Adam Gibson
- UCL Medical Physics & Biomedical Engineering, London, WC1E 6BT, United Kingdom
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Richmond N, Chester K, Manley S. Evaluation of the RadCalc collapsed cone dose calculation algorithm against measured data. Med Dosim 2023; 48:216-224. [PMID: 37164787 DOI: 10.1016/j.meddos.2023.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 03/31/2023] [Accepted: 04/11/2023] [Indexed: 05/12/2023]
Abstract
This work describes the experimental validation of the RadCalc (Lifeline software Inc, Tyler) collapsed cone dose calculation algorithm against measured data for a range of scenarios. 6 MV photon beam data were measured in a large water tank on a Varian TrueBeam linear accelerator. These were input into the RadCalc software, in conjunction with head geometry and output calibration information, then used to create a collapsed cone beam model. The model performance was assessed by comparison against measurement, using a selection of homogeneous and inhomogeneous geometries not incorporated into the original beam model. Dose calculations generated using the collapsed cone algorithm are generally in good agreement with measurement. However, the primary collimating of the linac is not accounted for in the RadCalc model and hence dose in the corners of large fields is significantly overestimated. Percentage depth doses were within 0.5% beyond a depth of 2 cm. The dose in the build-up region was underestimated by RadCalc Version 7.1.4.1, with (Distance To Agreement) discrepancies of up to 3 mm which were corrected in Version 7.2.2.0. Beam profiles for homogeneous phantom comparisons were within 2% in the central 80% of the field with out of field dose underestimated by no more than 3%. Dose comparisons in heterogeneous geometries were acceptable and generally within 3.5%. The largest observed differences were found at density interfaces and a result of the RadCalc dose resolution of 2 mm against 1 mm measured. Absolute dose comparisons demonstrated that RadCalc agreed with measurement to within 1.2% under homogeneous media irradiation geometries. For static beam IMRT deliveries agreement was within 2% or 2 mm of measured data, and for complex VMAT deliveries within 3% or 2 mm. The implementation of the (model-based) photon collapsed cone algorithm in RadCalc shows generally good agreement with measured data over a range of simple and complex scenarios considered.
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Affiliation(s)
- Neil Richmond
- Department of Radiotherapy Physics, Northern Centre for Cancer Care, Freeman Hospital, Newcastle upon Tyne, NE7 7DN, UK.
| | - Katherine Chester
- Department of Radiotherapy Physics, Northern Centre for Cancer Care, Freeman Hospital, Newcastle upon Tyne, NE7 7DN, UK
| | - Steven Manley
- Department of Medical Physics, The James Cook University Hospital, Middlesbrough, TS4 3BW, UK
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Wishart G, Gupta P, Nisbet A, Velliou E, Schettino G. Enhanced effect of X-rays in the presence of a static magnetic field within a 3D pancreatic cancer model. Br J Radiol 2023; 96:20220832. [PMID: 36475863 PMCID: PMC9975369 DOI: 10.1259/bjr.20220832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 11/23/2022] [Accepted: 12/02/2022] [Indexed: 12/12/2022] Open
Abstract
OBJECTIVE To evaluate the impact of static magnetic field (SMF) presence on the radiation response of pancreatic cancer cells in polyurethane-based highly macro-porous scaffolds in hypoxic (1% O2) and normoxic (21% O2) conditions, towards understanding MR-guided radiotherapy, shedding light on the potential interaction phenomenon between SMF and radiation in a three-dimensional (3D) microenvironment. METHODS Pancreatic cancer cells (PANC-1, ASPC-1) were seeded into fibronectin-coated highly porous polyethene scaffolds for biomimicry and cultured for 4 weeks in in vitro normoxia (21% O2) followed by a 2-day exposure to either in vitro hypoxia (1% O2) or maintenance in in vitro normoxia (21% O2). The samples were then irradiated with 6 MV photons in the presence or absence of a 1.5 T field. Thereafter, in situ post-radiation monitoring (1 and 7 days post-irradiation treatment) took place via quantification of (i) live dead and (ii) apoptotic profiles. RESULTS We report: (i) pancreatic ductal adenocarcinoma hypoxia-associated radioprotection, in line with our previous findings, (ii) an enhanced effect of radiation in the presence of SMFin in vitro hypoxia (1% O2) for both short- (1 day) and long-term (7 days) post -radiation analysis and (iii) an enhanced effect of radiation in the presence of SMF in in vitro normoxia (21% O2) for long-term (7 days) post-radiation analysis within a 3D pancreatic cancer model. CONCLUSION With limited understanding of the potential interaction phenomenon between SMF and radiation, this 3D system allows combination evaluation for a cancer in which the role of radiotherapy is still evolving. ADVANCES IN KNOWLEDGE This study examined the use of a 3D model to investigate MR-guided radiotherapy in a hypoxic microenvironment, indicating that this could be a useful platform to further understanding of SMF influence on radiation.
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Affiliation(s)
| | | | - Andrew Nisbet
- Department of Medical Physics and Biomedical Engineering, University College London (UCL), London, UK
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Giacometti V, King RB, McCreery C, Buchanan F, Jeevanandam P, Jain S, Hounsell AR, McGarry CK. 3D-printed patient-specific pelvis phantom for dosimetry measurements for prostate stereotactic radiotherapy with dominant intraprostatic lesion boost. Phys Med 2021; 92:8-14. [PMID: 34823110 DOI: 10.1016/j.ejmp.2021.10.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 09/29/2021] [Accepted: 10/30/2021] [Indexed: 10/19/2022] Open
Abstract
AIM Developing and assessing the feasibility of using a three-dimensional (3D) printed patient-specific anthropomorphic pelvis phantom for dose calculation and verification for stereotactic ablative radiation therapy (SABR) with dose escalation to the dominant intraprostatic lesions. MATERIAL AND METHODS A 3D-printed pelvis phantom, including bone-mimicking material, was fabricated based on the computed tomography (CT) images of a prostate cancer patient. To compare the extent to which patient and phantom body and bones overlapped, the similarity Dice coefficient was calculated. Modular cylindrical inserts were created to encapsulate radiochromic films and ionization chamber for absolute dosimetry measurements at the location of prostate and at the boost region. Gamma analysis evaluation with 2%/2mm criteria was performed to compare treatment planning system calculations and measured dose when delivering a 10 flattening filter free (FFF) SABR plan and a 10FFF boost SABR plan. RESULTS Dice coefficients of 0.98 and 0.91 were measured for body and bones, respectively, demonstrating agreement between patient and phantom outlines. For the boost plans the gamma analysis yielded 97.0% of pixels passing 2%/2mm criteria and these results were supported by the chamber average dose difference of 0.47 ± 0.03%. These results were further improved when overriding the bone relative electron density: 97.3% for the 2%/2mm gamma analysis, and 0.05 ± 0.03% for the ionization chamber average dose difference. CONCLUSIONS The modular patient-specific 3D-printed pelvis phantom has proven to be a highly attractive and versatile tool to validate prostate SABR boost plans using multiple detectors.
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Affiliation(s)
- Valentina Giacometti
- Patrick G. Johnston Centre for Cancer Research, Queen's University, Belfast, United Kingdom.
| | - Raymond B King
- Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, United Kingdom
| | - Craig McCreery
- School of Mechanical & Aerospace Engineering, Queen's University, Belfast, United Kingdom
| | - Fraser Buchanan
- School of Mechanical & Aerospace Engineering, Queen's University, Belfast, United Kingdom
| | - Prakash Jeevanandam
- Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, United Kingdom
| | - Suneil Jain
- Patrick G. Johnston Centre for Cancer Research, Queen's University, Belfast, United Kingdom; Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, United Kingdom
| | - Alan R Hounsell
- Patrick G. Johnston Centre for Cancer Research, Queen's University, Belfast, United Kingdom; Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, United Kingdom
| | - Conor K McGarry
- Patrick G. Johnston Centre for Cancer Research, Queen's University, Belfast, United Kingdom; Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, United Kingdom
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Silvestre Patallo I, Carter R, Maughan D, Nisbet A, Schettino G, Subiel A. Evaluation of a micro ionization chamber for dosimetric measurements in image-guided preclinical irradiation platforms. Phys Med Biol 2021; 66. [PMID: 34794132 DOI: 10.1088/1361-6560/ac3b35] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 11/18/2021] [Indexed: 11/12/2022]
Abstract
Image-guided small animal irradiation platforms deliver small radiation fields in the medium energy x-ray range. Commissioning of such platforms, followed by dosimetric verification of treatment planning, are mostly performed with radiochromic film. There is a need for independent measurement methods, traceable to primary standards, with the added advantage of immediacy in obtaining results. This investigation characterizes a small volume ionization chamber in medium energy x-rays for reference dosimetry in preclinical irradiation research platforms. The detector was exposed to a set of reference x-ray beams (0.5 to 4 mm Cu HVL). Leakage, reproducibility, linearity, response to detector's orientation, dose rate, and energy dependence were determined for a 3D PinPoint ionization chamber (PTW 31022). Polarity and ion recombination were also studied. Absorbed doses at 2 cm depth were compared, derived either by applying the experimentally determined cross-calibration coefficient at a typical small animal radiation platform "user's" quality (0.84 mm Cu HVL) or by interpolation from air kerma calibration coefficients in a set of reference beam qualities. In the range of reference x-ray beams, correction for ion recombination was less than 0.1%. The largest polarity correction was 1.4% (for 4 mm Cu HVL). Calibration and correction factors were experimentally determined. Measurements of absorbed dose with the PTW 31022, in conditions different from reference were successfully compared to measurements with a secondary standard ionization chamber. The implementation of an End-to-End test for delivery of image-targeted small field plans resulted in differences smaller than 3% between measured and treatment planning calculated doses. The investigation of the properties and response of a PTW 31022 small volume ionization chamber in medium energy x-rays and small fields can contribute to improve measurement uncertainties evaluation for reference and relative dosimetry of small fields delivered by preclinical irradiators while maintaining the traceability chain to primary standards.
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Affiliation(s)
- Ileana Silvestre Patallo
- Medical, Marine & Nuclear: Medical Radiation Physics&Sciences, National Physical Laboratory, Teddington, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Rebecca Carter
- Cancer Institute, University College London, London, London, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - David Maughan
- Medical, Marine & Nuclear: Medical Radiation Physics&Sciences, National Physical Laboratory, Teddington, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Andrew Nisbet
- Department of Medical Physics & Biomedical Engineering, University College London, London, London, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Giuseppe Schettino
- Medical, Marine & Nuclear: Medical Radiation Physics&Sciences, National Physical Laboratory, Teddington, Middlesex, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Anna Subiel
- Medical, Marine & Nuclear: Medical Radiation Physics&Sciences, National Physical Laboratory, Teddington, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
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Billas I, Bouchard H, Oelfke U, Duane S. Traceable reference dosimetry in MRI guided radiotherapy using alanine: calibration and magnetic field correction factors of ionisation chambers. Phys Med Biol 2021; 66. [PMID: 34049290 DOI: 10.1088/1361-6560/ac0680] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 05/28/2021] [Indexed: 12/27/2022]
Abstract
Magnetic resonance imaging (MRI)-guided radiotherapy (RT) (MRIgRT) falls outside the scope of existing high energy photon therapy dosimetry protocols, because those protocols do not consider the effects of the magnetic field on detector response and on absorbed dose to water. The aim of this study is to evaluate and demonstrate the traceable measurement of absorbed dose in MRIgRT systems using alanine, made possible by the characterisation of alanine sensitivity to magnetic fields reported previously by Billaset al(2020Phys. Med. Biol.65115001), in a way which is compatible with existing standards and calibrations available for conventional RT. In this study, alanine is used to transfer absorbed dose to water to MRIgRT systems from a conventional linac. This offers an alternative route for the traceable measurement of absorbed dose to water, one which is independent of the transfer using ionisation chambers. The alanine dosimetry is analysed in combination with measurements with several Farmer-type chambers, PTW 30013 and IBA FC65-G, at six different centres and two different MRIgRT systems (Elekta Unity™ and ViewRay MRIdian™). The results are analysed in terms of the magnetic field correction factors, and in terms of the absorbed dose calibration coefficients for the chambers, determined at each centre. This approach to reference dosimetry in MRIgRT produces good consistency in the results, across the centres visited, at the level of 0.4% (standard deviation). Farmer-type ionisation chamber magnetic field correction factors were determined directly, by comparing calibrations in some MRIgRT systems with and without the magnetic field ramped up, and indirectly, by comparing calibrations in all the MRIgRT systems with calibrations in a conventional linac. Calibration coefficients in the MRIgRT systems were obtained with a standard uncertainty of 1.1% (Elekta Unity™) and 0.9% (ViewRay MRIdian™), for three different chamber orientations with respect to the magnetic field. The values obtained for the magnetic field correction factor in this investigation are consistent with those presented in the summary by de Pooteret al(2021Phys. Med. Biol.6605TR02), and would tend to support the adoption of a magnetic field correction factor which depends on the chamber type, PTW 30013 or IBA FC65-G.
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Affiliation(s)
- Ilias Billas
- National Physical Laboratory, Teddington, United Kingdom.,Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, United Kingdom
| | - Hugo Bouchard
- Université de Montréal, Département de Physique, Montréal, Canada and Centre Hospitalier de l'Université de Montréal, Montréal, Canada and Centre de recherche du CHUM, Montréal, Canada
| | - Uwe Oelfke
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, United Kingdom
| | - Simon Duane
- National Physical Laboratory, Teddington, United Kingdom
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Bolt M, Clark CH, Nisbet A, Chen T. Quantification of the uncertainties within the radiotherapy dosimetry chain and their impact on tumour control. Phys Imaging Radiat Oncol 2021; 19:33-38. [PMID: 34307916 PMCID: PMC8295844 DOI: 10.1016/j.phro.2021.06.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 06/17/2021] [Accepted: 06/21/2021] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND AND PURPOSE Dose delivered during radiotherapy has uncertainty arising from a number of sources including machine calibration, treatment planning and delivery and can impact outcomes. Any systematic uncertainties will impact all patients and can continue for extended periods. The impact on tumour control probability (TCP) of the uncertainties within the radiotherapy calibration process has been assessed. MATERIALS AND METHODS The linear-quadratic model was used to simulate the TCP from two prostate cancer and a head and neck (H&N) clinical trial. The uncertainty was separated into four components; 1) initial calibration, 2) systematic shift due to output drift, 3) drift during treatment and 4) daily fluctuations. Simulations were performed for each clinical case to model the variation in TCP present at the end of treatment arising from the different components. RESULTS Overall uncertainty in delivered dose was +/-2.1% (95% confidence interval (CI)), consisting of uncertainty standard deviations of 0.7% in initial calibration, 0.8% due to subsequent calibration shift due to output drift, 0.1% due to drift during treatment, and 0.2% from daily variations. The overall uncertainty of TCP (95% CI) for a population of patients treated on different machines was +/-3%, +/-5%, and +/-3% for simulations based on the two prostate trials and H&N trial respectively. CONCLUSION The greatest variation in delivered target volume dose arose from calibration shift due to output drift. Careful monitoring of beam output following initial calibration remains vital and may have a significant impact on clinical outcomes.
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Affiliation(s)
- Matthew Bolt
- Department of Medical Physics, St Luke’s Cancer Centre, Royal Surrey County Hospital NHS Foundation Trust, Guildford, UK
- National Physical Laboratory, Teddington, UK
- Department of Chemical and Process Engineering, University of Surrey, Guildford, UK
| | - Catharine H. Clark
- National Physical Laboratory, Teddington, UK
- Radiotherapy Physics, University College London Hospital NHS Foundation Trust, London, UK
| | - Andrew Nisbet
- Department of Medical Physics and Biomedical Engineering, University College London, London, UK
| | - Tao Chen
- Department of Chemical and Process Engineering, University of Surrey, Guildford, UK
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Report dose-to-medium in clinical trials where available; a consensus from the Global Harmonisation Group to maximize consistency. Radiother Oncol 2021; 159:106-111. [PMID: 33741471 DOI: 10.1016/j.radonc.2021.03.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 03/05/2021] [Accepted: 03/06/2021] [Indexed: 11/22/2022]
Abstract
PURPOSE To promote consistency in clinical trials by recommending a uniform framework as it relates to radiation transport and dose calculation in water versus in medium. METHODS The Global Quality Assurance of Radiation Therapy Clinical Trials Harmonisation Group (GHG; www.rtqaharmonization.org) compared the differences between dose to water in water (Dw,w), dose to water in medium (Dw,m), and dose to medium in medium (Dm,m). This was done based on a review of historical frameworks, existing literature and standards, clinical issues in the context of clinical trials, and the trajectory of radiation dose calculations. Based on these factors, recommendations were developed. RESULTS No framework was found to be ideal or perfect given the history, complexity, and current status of radiation therapy. Nevertheless, based on the evidence available, the GHG established a recommendation preferring dose to medium in medium (Dm,m). CONCLUSIONS Dose to medium in medium (Dm,m) is the preferred dose calculation and reporting framework. If an institution's planning system can only calculate dose to water in water (Dw,w), this is acceptable.
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Affiliation(s)
- Catharine H. Clark
- Medical Physics Department, Royal Surrey County Hospital, Guildford Surrey, UK
- Metrology for Medical Physics, National Physical Laboratory, Teddington, Middx, UK
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