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Muir B, Davis S, Dhanesar S, Hillman Y, Iakovenko V, Kim GGY, Alves VGL, Lei Y, Lowenstein J, Renaud J, Sarfehnia A, Siebers J, Tantôt L. AAPM WGTG51 Report 385: Addendum to the AAPM's TG-51 protocol for clinical reference dosimetry of high-energy electron beams. Med Phys 2024. [PMID: 38980220 DOI: 10.1002/mp.17277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 03/29/2024] [Accepted: 06/14/2024] [Indexed: 07/10/2024] Open
Abstract
An Addendum to the AAPM's TG-51 protocol for the determination of absorbed dose to water is presented for electron beams with energies between 4 MeV and 22 MeV (1.70 cm ≤ R 50 ≤ 8.70 cm $1.70\nobreakspace {\rm cm} \le R_{\text{50}} \le 8.70\nobreakspace {\rm cm}$ ). This updated formalism allows simplified calibration procedures, including the use of calibrated cylindrical ionization chambers in all electron beams without the use of a gradient correction. Newk Q $k_{Q}$ data are provided for electron beams based on Monte Carlo simulations. Implementation guidance is provided. Components of the uncertainty budget in determining absorbed dose to water at the reference depth are discussed. Specifications for a reference-class chamber in electron beams include chamber stability, settling, ion recombination behavior, and polarity dependence. Progress in electron beam reference dosimetry is reviewed. Although this report introduces some major changes (e.g., gradient corrections are implicitly included in the electron beam quality conversion factors), they serve to simplify the calibration procedure. Results for absorbed dose per linac monitor unit are expected to be up to approximately 2 % higher using this Addendum compared to using the original TG-51 protocol.
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Affiliation(s)
- Bryan Muir
- Metrology Research Centre, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Stephen Davis
- Department of Radiation Oncology, Miami Cancer Institute, Miami, Florida, USA
| | - Sandeep Dhanesar
- Department of Radiation Oncology, Houston Methodist Hospital, Houston, Texa, USA
| | - Yair Hillman
- Department of Radiation Oncology, Sharett Institute of Oncology, Hadassah Medical Center, Hebrew University of Jerusalem, Jerusalem, Israel
| | | | - Grace Gwe-Ya Kim
- Department of Radiation Medicine and Applied Sciences, UC San Diego School of Medicine, San Diego, California, USA
| | | | - Yu Lei
- Department of Radiation Oncology, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Jessica Lowenstein
- Department of Radiation Physics, UT M.D. Anderson Cancer Center, Houston, Texa, USA
| | - James Renaud
- Metrology Research Centre, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Arman Sarfehnia
- Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada
- Department of Medical Physics, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
| | - Jeffrey Siebers
- Department of Radiation Oncology, University of Virginia, Charlottesville, Virginia, USA
| | - Laurent Tantôt
- Département de radio-oncologie, CIUSSS de l'Est-de-l'Île-de-Montréal - Hôpital Maisonneuve-Rosemont, Montreal, Quebec, Canada
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McDermott PN. Monte Carlo evaluation of uncertainties in photon and electron TG-51 absorbed dose calibration. J Appl Clin Med Phys 2024; 25:e14339. [PMID: 38608655 PMCID: PMC11244687 DOI: 10.1002/acm2.14339] [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: 06/21/2023] [Revised: 02/09/2024] [Accepted: 03/03/2024] [Indexed: 04/14/2024] Open
Abstract
PURPOSE The accuracy of dose delivery to all patients treated with medical linacs depends on the accuracy of beam calibration. Dose delivery cannot be any more accurate than this. Given the importance of this, it seems worthwhile taking another look at the expected uncertainty in TG-51 photon dose calibration and a first look at electron calibration. This work builds on the 2014 addendum to TG-51 for photons and adds to it by also considering electrons. In that publication, estimates were made of the uncertainty in the dose calibration. In this paper, we take a deeper look at this important issue. METHODS The methodology used here is more rigorous than previous determinations as it is based on Monte Carlo simulation of uncertainties. It is assumed that mechanical QA has been performed following TG-142 prior to beam calibration and that there are no uncertainties that exceed the tolerances specified by TG-142. RESULTS/CONCLUSIONS Despite the different methodology and assumptions, the estimated uncertainty in photon beam calibration is close to that in the addendum. The careful user should be able to easily reach a 95% confidence interval (CI) of ± 2.3% for photon beam calibration with standard instrumentation. For electron beams calibrated with a Farmer chamber, the estimated uncertainties are slightly larger, and the 95% CI is ±2.6% for 6 MeV and slightly smaller than this for 18 MeV. There is no clear energy dependence in these results. It is unlikely that the user will be able to improve on these uncertainties as the dominant factor in the uncertainty resides in the ion chamber dose calibration factorN D , w 60 Co $N_{D,w}^{{}^{60}{\mathrm{Co}}}$ . For both photons and electrons, reduction in the ion chamber depth uncertainty below about 0.5 mm and SSD uncertainty below 1 mm have almost no effect on the total dose uncertainty, as uncertainties beyond the user's control totally dominate under these circumstances.
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Affiliation(s)
- Patrick N McDermott
- Department of Radiation Oncology, William Beaumont University Hospital, Corewell Health, Royal Oak, Michigan, USA
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Mizuno H, Nakaji T, Fukuda S, Kato S. End-to-end dosimetry audit for three-dimensional image-guided brachytherapy for cervical cancer. Phys Med 2024; 119:103321. [PMID: 38394979 DOI: 10.1016/j.ejmp.2024.103321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 02/08/2024] [Accepted: 02/12/2024] [Indexed: 02/25/2024] Open
Abstract
BACKGROUND End-to-end dosimetry audit for brachytherapy is challenging due to the steep dose gradient. However, it is an efficient method to detect unintended errors in actual clinical practice. PURPOSE We aimed to develop an on-site end-to-end test phantom for three-dimensional image-guided brachytherapy (IGBT) for cervical cancer. METHODS The test phantom we developed consisted of a water tank with an applicator/detector holder. The holder was designed to accommodate the applicator and insert an ionization chamber (PinPoint; PTW, Freiburg, Germany) to measure the dose at point A. Imaging and reconstruction were performed in the same way as performed for a patient. The feasibility of our test phantom was assessed in two different hospitals using tandem and ovoid (made of either metal or carbon) applicators that the hospitals provided. RESULTS The measured and calculated doses at point A were compared for each applicator. We observed that the values obtained using metal applicators were consistently lower, on an average by -2.3%, than the calculated values, while those obtained using carbon applicators were comparable to the calculated values. This difference can be attributed to the attenuation of the dose by the metal applicators, resulting in a lower dose at point A. The majority of treatment planning system, including the one used in this study, do not account for the material of applicator. CONCLUSIONS An end-to-end test phantom for IGBT was developed, tested, and applied in a dosimetry audit in hospitals and showed favorable results for evaluating the point A dose.
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Affiliation(s)
- Hideyuki Mizuno
- Radiation quality control section, QST Hospital, National Institutes for Quantum Science and Technology, Chiba, Japan.
| | - Taku Nakaji
- Radiation quality control section, QST Hospital, National Institutes for Quantum Science and Technology, Chiba, Japan
| | - Shigekazu Fukuda
- Radiation quality control section, QST Hospital, National Institutes for Quantum Science and Technology, Chiba, Japan
| | - Shingo Kato
- Saitama Medical University International Medical Centre, Hidaka, Saitama, Japan
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Dimitriadis A, Kazantsev P, Chelminski K, Titovich E, Naida E, Magnus T, Meghzifene A, Azangwe G, Carrara M, Swamidas J. IAEA/WHO postal dosimetry audit methodology for electron beams using radio photoluminescent dosimeters. Med Phys 2023; 50:7214-7221. [PMID: 37793099 DOI: 10.1002/mp.16776] [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: 03/29/2023] [Revised: 06/02/2023] [Accepted: 09/23/2023] [Indexed: 10/06/2023] Open
Abstract
BACKGROUND Independent dosimetry audits are an important intervention in radiotherapy for quality assurance. Electron beams, used for superficial radiotherapy treatments, must also be tested in dosimetry audits as part of a good quality assurance program to help prevent clinical errors. PURPOSE To establish a new service for IAEA/WHO postal dosimetry audits in electron beams using RPL dosimeters. METHODS A novel postal audit methodology employing a PMMA holder system for RPLDs was developed. The associated correction factors including holder dependence, energy dependence, dose response non-linearity, and fading were obtained and tested in a multi-center (n = 12) pilot study. A measurement uncertainty budget was estimated and employed in analyzing the irradiated dosimeters. RESULTS Holder and energy correction factors ranged from 1.004 to 1.010 and 1.019 to 1.059 respectively across the energy range. The non-linearity and fading correction models used for photon beams were tested in electron beams and did not significantly increase measurement uncertainty. The mean dose ratio ± SD of the multi-center study was 1.001 ± 0.011. The overall uncertainty budget was estimated as ± 1.42% (k = 1). CONCLUSIONS A methodology for IAEA/WHO postal dosimetry audits in electron beams was developed and validated in a multi-center study and is now made available to radiotherapy centers as a routine service.
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Affiliation(s)
- Alexis Dimitriadis
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Pavel Kazantsev
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Krzysztof Chelminski
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Egor Titovich
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Ekaterina Naida
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Talent Magnus
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Ahmed Meghzifene
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Godfrey Azangwe
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Mauro Carrara
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
| | - Jamema Swamidas
- Dosimetry and Medical Radiation Physics Section, Division of Human Health, Department of Nuclear Sciences and Applications, International Atomic Energy Agency, Vienna, Austria
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Nakamura M, Zhou D, Minemura T, Kito S, Okamoto H, Tohyama N, Kurooka M, Kumazaki Y, Ishikawa M, Clark CH, Miles E, Lehmann J, Andratschke N, Kry S, Ishikura S, Mizowaki T, Nishio T. A virtual audit system for intensity-modulated radiation therapy credentialing in Japan Clinical Oncology Group clinical trials: A pilot study. J Appl Clin Med Phys 2023:e14040. [PMID: 37191875 DOI: 10.1002/acm2.14040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 04/20/2023] [Accepted: 04/24/2023] [Indexed: 05/17/2023] Open
Abstract
PURPOSE The Medical Physics Working Group of the Radiation Therapy Study Group at the Japan Clinical Oncology Group is currently developing a virtual audit system for intensity-modulated radiation therapy dosimetry credentialing. The target dosimeters include films and array detectors, such as ArcCHECK (Sun Nuclear Corporation, Melbourne, Florida, USA) and Delta4 (ScandiDos, Uppsala, Sweden). This pilot study investigated the feasibility of our virtual audit system using previously acquired data. METHODS We analyzed 46 films (32 and 14 in the axial and coronal planes, respectively) from 29 institutions. Global gamma analysis between measured and planned dose distributions used the following settings: 3%/3 mm criteria (the dose denominator was 2 Gy), 30% threshold dose, no scaling of the datasets, and 90% tolerance level. In addition, 21 datasets from nine institutions were obtained for array evaluation. Five institutions used ArcCHECK, while the others used Delta4. Global gamma analysis was performed with 3%/2 mm criteria (the dose denominator was the maximum calculated dose), 10% threshold dose, and 95% tolerance level. The film calibration and gamma analysis were conducted with in-house software developed using Python (version 3.9.2). RESULTS The means ± standard deviations of the gamma passing rates were 99.4 ± 1.5% (range, 92.8%-100%) and 99.2 ± 1.0% (range, 97.0%-100%) in the film and array evaluations, respectively. CONCLUSION This pilot study demonstrated the feasibility of virtual audits. The proposed virtual audit system will contribute to more efficient, cheaper, and more rapid trial credentialing than on-site and postal audits; however, the limitations should be considered when operating our virtual audit system.
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Affiliation(s)
- Mitsuhiro Nakamura
- Department of Advanced Medical Physics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Dejun Zhou
- Department of Advanced Medical Physics, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | | | - Satoshi Kito
- Department of Radiation Oncology, Tokyo Metropolitan Cancer and Infectious Disease Center Komagome Hospital, Tokyo, Japan
| | - Hiroyuki Okamoto
- Radiation Safety and Quality Assurance Division, National Cancer Center Hospital, Tokyo, Japan
| | - Naoki Tohyama
- Division of Medical Physics, Tokyo Bay Makuhari Clinic for Advanced Imaging, Cancer Screening, and High-Precision Radiotherapy, Chiba, Japan
| | - Masahiko Kurooka
- Department of Radiation Therapy, Tokyo Medical University Hospital, Tokyo, Japan
| | - Yu Kumazaki
- Department of Radiation Oncology, International Medical Center, Saitama Medical University, Saitama, Japan
| | | | - Catharine H Clark
- National Radiotherapy Trials Quality Assurance (RTTQA) Group, Royal Surrey NHS Foundation Trust, London, UK
- Department of Radiotherapy Physics, University College London Hospital, London, UK
- Department of Medical Physics and Bioengineering, University College London, London, UK
- Medical Physics department, National Physical Laboratory (NPL), Teddington, UK
| | - Elizabeth Miles
- National Radiotherapy Trials Quality Assurance (RTTQA) Group, Mount Vernon Cancer Centre, Northwood, UK
| | - Joerg Lehmann
- Trans Tasman Radiation Oncology Group (TROG), Newcastle, Australia
- Department of Radiation Oncology, Calvary Mater Hospital, Newcastle, Australia
- School of Information and Physical Sciences, University of Newcastle, Newcastle, Australia
- Institute of Medical Physics, University of Sydney, Sydney, Australia
| | - Nicolaus Andratschke
- Department of Radiation Oncology, University Hospital of Zurich, University of Zurich, Zurich, Switzerland
| | - Stephen Kry
- Imaging and Radiation Oncology Core (IROC), The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Satoshi Ishikura
- Division of Radiation Oncology, Tokyo Bay Makuhari Clinic for Advanced Imaging, Cancer Screening, and High-Precision Radiotherapy, Chiba, Japan
| | - Takashi Mizowaki
- Department of Radiation Oncology and Image-Applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Teiji Nishio
- Medical Physics Laboratory, Division of Health Science, Graduate School of Medicine, Osaka University, Osaka, Japan
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Muir B, Culberson W, Davis S, Kim GGY, Lee SW, Lowenstein J, Renaud J, Sarfehnia A, Siebers J, Tantôt L, Tolani N. AAPM WGTG51 Report 374: Guidance for TG-51 reference dosimetry. Med Phys 2022; 49:6739-6764. [PMID: 36000424 DOI: 10.1002/mp.15949] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 07/21/2022] [Accepted: 07/27/2022] [Indexed: 12/13/2022] Open
Abstract
Practical guidelines that are not explicit in the TG-51 protocol and its Addendum for photon beam dosimetry are presented for the implementation of the TG-51 protocol for reference dosimetry of external high-energy photon and electron beams. These guidelines pertain to: (i) measurement of depth-ionization curves required to obtain beam quality specifiers for the selection of beam quality conversion factors, (ii) considerations for the dosimetry system and specifications of a reference-class ionization chamber, (iii) commissioning a dosimetry system and frequency of measurements, (iv) positioning/aligning the water tank and ionization chamber for depth ionization and reference dose measurements, (v) requirements for ancillary equipment needed to measure charge (triaxial cables and electrometers) and to correct for environmental conditions, and (vi) translation from dose at the reference depth to that at the depth required by the treatment planning system. Procedures are identified to achieve the most accurate results (errors up to 8% have been observed) and, where applicable, a commonly used simplified procedure is described and the impact on reference dosimetry measurements is discussed so that the medical physicist can be informed on where to allocate resources.
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Affiliation(s)
- Bryan Muir
- Metrology Research Centre, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Wesley Culberson
- Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin, United States
| | - Stephen Davis
- Radiation Oncology, Miami Cancer Institute, Miami, Florida, United States
| | - Grace Gwe-Ya Kim
- Department of Radiation Medicine and Applied Sciences, UC San Diego School of Medicine, La Jolla, California, United States
| | - Sung-Woo Lee
- Department of Radiation Oncology, University of Maryland School of Medicine, Columbia, Maryland, United States
| | - Jessica Lowenstein
- Department of Radiation Physics, UT M.D. Anderson Cancer Center, Houston, Texas, United States
| | - James Renaud
- Metrology Research Centre, National Research Council of Canada, Ottawa, Ontario, Canada
| | - Arman Sarfehnia
- Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
| | - Jeffrey Siebers
- Department of Radiation Oncology, University of Virginia Health System, Charlottesville, Virginia, United States
| | - Laurent Tantôt
- Département de radio-oncologie, CIUSSS de l'Est-de-l'Île-de-Montréal - Hôpital Maisonneuve-Rosemont, Montreal, Quebec, Canada
| | - Naresh Tolani
- Department of Radiation Therapy, Michael E. DeBakey VA Medical Center, Houston, Texas, United States
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Safwan Ahmad Fadzil M, Mohd Noor N, Ngie Min U, Abdullah N, Taufik Dolah M, Pawanchek M, Andrew Bradley D. Dosimetry audit for megavoltage photon beams applied in non-reference conditions. Phys Med 2022; 100:99-104. [PMID: 35779357 DOI: 10.1016/j.ejmp.2022.06.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 06/12/2022] [Accepted: 06/13/2022] [Indexed: 11/19/2022] Open
Abstract
PURPOSE We have conducted for the first time a Malaysian postal dosimetry audit of external beam under non-reference conditions by evaluating the output performance while screening for systematic errors within the dosimetry chain. The potential use from the choice of detector were investigated along with the search for other sources of discrepancies. METHODS Ten radiotherapy centres were audited, encompassing 16 megavoltage photon beam arrangements, adopting the IAEA postal dosimetry protocol for non-reference conditions, with a holder modified to accommodate three TLD types: Ge-doped cylindrical silica fibres (CF), Ge-doped flat silica fibres (FF), and TLD-100 powder. RESULTS Eight of the centres operated within ± 5% of stated dose, one other exceeding tolerance for all measured points, and one did not return any dosimeters for analysis after failing the initial irradiations. Post remedial measures, the mean relative response for CF, FF, and TLD-100 was 1.00, 0.99, and 0.98 respectively, with associated coefficients of variation 6.87%, 6.45%, and 5.06%. CONCLUSION High quality radiotherapy clinical practice postal dosimetry audits that are based on sensitive TLDs are seen to be particularly effective in identifying and resolving dose delivery discrepancies.
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Affiliation(s)
- Muhammad Safwan Ahmad Fadzil
- Department of Radiology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia; Diagnostic Imaging and Radiotherapy Program, Centre for Diagnostic, Therapeutic and Investigative Studies, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, 50300 Kuala Lumpur, Malaysia
| | - Noramaliza Mohd Noor
- Department of Radiology, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia.
| | - Ung Ngie Min
- Clinical Oncology Unit, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia
| | - Norhayati Abdullah
- Radiation Safety and Health Division, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor, Malaysia
| | - Mohd Taufik Dolah
- Radiation Safety and Health Division, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor, Malaysia
| | - Mahzom Pawanchek
- Department of Radiotherapy and Oncology, National Cancer Institute, 62250 W.P. Putrajaya, Malaysia
| | - David Andrew Bradley
- Centre for Applied Physics and Radiation Technologies, School of Engineering and Technology, Sunway University, 47500 Petaling Jaya, Selangor, Malaysia; Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH, United Kingdom
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Abdullah N, Bradley D, Nisbet A, Kamarul Zaman Z, Deraman S, Mohd Noor N. Dosimetric characteristics of fabricated germanium doped optical fibres for a postal audit of therapy electron beams. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Lehmann J, Hussein M, Barry M, Siva S, Moore A, Chu M, Díez P, Eaton DJ, Harwood J, Lonski P, Claridge Mackonis E, Meehan C, Patel R, Ray X, Shaw M, Shepherd J, Smyth G, Standen TS, Subramanian B, Greer P, Clark CH. SEAFARER – A new concept for validating radiotherapy patient specific QA for clinical trials and clinical practice. Radiother Oncol 2022; 171:121-128. [DOI: 10.1016/j.radonc.2022.04.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 03/22/2022] [Accepted: 04/14/2022] [Indexed: 01/12/2023]
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Mizuno H, Yamashita W, Okuyama H, Takase N, Nakaji T, Fukuda S. Analysis of the uncertainties in the dose audit system using radiophotoluminescent glass dosimeters in Japanese radiotherapy units. RADIAT MEAS 2022. [DOI: 10.1016/j.radmeas.2022.106753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Mizuno H, Yamashita W, Okuyama H, Takase N, Tohyama N, Shimizu H, Fujita Y, Kito S, Nakaji T, Fukuda S. Dose response of a radiophotoluminescent glass dosimeter for TomoTherapy, CyberKnife, and flattening-filter-free linear accelerator output measurements in dosimetry audit. Phys Med 2021; 88:91-97. [PMID: 34214838 DOI: 10.1016/j.ejmp.2021.06.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 05/11/2021] [Accepted: 06/04/2021] [Indexed: 11/19/2022] Open
Abstract
PURPOSE We experimentally determined the radiophotoluminescent glass dosimeter (RPLD) dose responses for TomoTherapy, CyberKnife, and flattening-filter-free (FFF) linear accelerator (linac) outputs for dosimetry audits in Japan. METHODS A custom-made solid phantom with a narrow central-axis spacing of three RPLD elements was used for output measurement to minimise the dose-gradient effect of the non-flattening filter beams. For RPLD dose estimation, we used the ISO 22127 formalism. Additional unit-specific correction factors were introduced and determined via the measured data. For TomoTherapy (7 units) and CyberKnife (4 units), the doses were measured under machine-specific reference fields. For FFF linac (5 units), in addition to the reference condition, we obtained the field-size effects for the range from 5×5 cm to 25×25 cm. RESULTS The correction factors were estimated as 1.008 and 0.999 for TomoTherapy and CyberKnife, respectively. For FFF linac, they ranged from 1.011 to 0.988 for 6 MV and from 1.011 to 0.997 for 10 MV as a function of the side length of the square field from 5 to 25 cm. The estimated uncertainties of the absorbed dose to water measured by RPLD for the units were 1.32%, 1.35%, and 1.30% for TomoTherapy, CyberKnife, and FFF linac, respectively. A summary of the dosimetry audits of these treatment units using the obtained correction factors is also presented. The average percentage differences between the measured and hospital-stated doses were <1% under all conditions. CONCLUSION RPLD can be successfully used as a dosimetry audit tool for modern treatment units.
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Affiliation(s)
- Hideyuki Mizuno
- QST Hospital, National Institutes for Quantum and Radiological Science and Technology, Japan.
| | | | | | | | - Naoki Tohyama
- Tokyo Bay Advanced Imaging & Radiation Oncology Makuhari Clinic, Japan
| | | | | | - Satoshi Kito
- Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Japan; Graduate School of Medicine, Kyoto University, Japan
| | - Taku Nakaji
- QST Hospital, National Institutes for Quantum and Radiological Science and Technology, Japan
| | - Shigekazu Fukuda
- QST Hospital, National Institutes for Quantum and Radiological Science and Technology, Japan
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12
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Sempau J, Kazantsev P, Izewska J, Brualla L. Monte Carlo verification of the holder correction factors for the radiophotoluminescent glass dosimeter used by the IAEA in international dosimetry audits. Phys Med 2021; 86:1-5. [PMID: 34044284 DOI: 10.1016/j.ejmp.2021.04.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 04/08/2021] [Accepted: 04/14/2021] [Indexed: 11/29/2022] Open
Abstract
The International Atomic Energy Agency (IAEA), jointly with the World Health Organization (WHO), has operated a postal dosimetry audit program for radiotherapy centers worldwide since 1969. In 2017 the IAEA introduced a new methodology based on radiophotoluminescent dosimetry (RPLD) for these audits. The detection system consists of a phosphate glass dosimeter inserted in a plastic capsule that is kept in measuring position with a PMMA holder during irradiation. Correction factors for this holder were obtained using experimental methods. In this work these methods are described and the resulting factors are verified by means of Monte Carlo simulation with the general-purpose code PENELOPE for a range of photon beam qualities relevant in radiotherapy. The study relies on a detailed geometrical representation of the experimental setup. Various photon beams were obtained from faithful modeling of the corresponding linacs. Monte Carlo simulation transport parameters are selected to ensure subpercent accuracy. The simulated correction factors fall in the interval 1.005-1.008 (±0.2%), with deviations with respect to experimental values not larger than 0.2(2)%. This study corroborates the validity of the holder correction factors currently used for the IAEA audits.
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Affiliation(s)
- J Sempau
- Universitat Politècnica de Catalunya, E-08028 Barcelona, Spain; Centros de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), E-28029 Madrid, Spain
| | - P Kazantsev
- International Atomic Energy Agency, A-1400 Vienna, Austria
| | - J Izewska
- International Atomic Energy Agency, A-1400 Vienna, Austria
| | - L Brualla
- West German Proton Therapy Centre WPE, D-45147 Essen, Germany; University of Duisburg-Essen, Faculty of Medicine, D-45147 Essen, Germany; University Hospital Essen, West German Cancer Center WTZ, D-45147 Essen, Germany.
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Mittauer KE, Hill PM, Bassetti MF, Bayouth JE. Validation of an MR-guided online adaptive radiotherapy (MRgoART) program: Deformation accuracy in a heterogeneous, deformable, anthropomorphic phantom. Radiother Oncol 2020; 146:97-109. [DOI: 10.1016/j.radonc.2020.02.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 02/12/2020] [Accepted: 02/15/2020] [Indexed: 01/11/2023]
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Izewska J, Bokulic T, Kazantsev P, Wesolowska P, van der Merwe D. 50 Years of the IAEA/WHO postal dose audit programme for radiotherapy: what can we learn from 13756 results? Acta Oncol 2020; 59:495-502. [PMID: 32036736 DOI: 10.1080/0284186x.2020.1723162] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Background: The IAEA/WHO postal dose audit programme has been operating since 1969 with the aim of improving the accuracy and consistency of dosimetry in radiotherapy in low-income and middle-income countries world-wide. This study summarises the 50 years' experience of audits and explores the quality of reference dosimetry in participating radiotherapy centres throughout the years.Material and methods: During the IAEA/WHO postal audits the dose determined from the mailed dosimeter is compared with that stated by the participant. Agreement to within ±5% is regarded acceptable whilst deviations outside ±5% limits trigger follow-up actions. Of particular interest in this study was the dependence of clinical dosimetry quality on factors related to the centre infrastructure and expertise in dosimetry of its staff.Results: The IAEA/WHO dose audit programme noted great increase in the overall percentage of acceptable results from about 50% in its early years to 99% at present, although there is some variability of results amongst participating countries. Whereas results for younger radiotherapy machines show the agreement rate between the measured and the stated doses well above 90%, for those over 20 years old the rate dropped to <80%. Linac dosimetry was always better than 60Co dosimetry and multi-machine centres generally performed better than single machine centres equipped with cobalt alone. Second and subsequent participation in audits showed higher quality dosimetry than the first participation. The implementation of modern dosimetry protocols resulted in more accurate dosimetry than the use of the older protocols.Conclusions: Over the 50 years that the IAEA has accumulated dosimetry audit data, practices in radiotherapy centres have significantly improved. Higher quality dosimetry confirmed in audits is generally associated with better infrastructure and adequate dosimetry expertise of medical physicists in participating centres.
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Affiliation(s)
- Joanna Izewska
- Dosimetry and Medical Radiation Physics Section, International Atomic Energy Agency, Vienna, Austria
| | - Tomislav Bokulic
- Dosimetry and Medical Radiation Physics Section, International Atomic Energy Agency, Vienna, Austria
| | - Pavel Kazantsev
- Dosimetry and Medical Radiation Physics Section, International Atomic Energy Agency, Vienna, Austria
| | - Paulina Wesolowska
- Dosimetry and Medical Radiation Physics Section, International Atomic Energy Agency, Vienna, Austria
| | - Debbie van der Merwe
- Dosimetry and Medical Radiation Physics Section, International Atomic Energy Agency, Vienna, Austria
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Kazantsev P, Lechner W, Gershkevitsh E, Clark CH, Venencia D, Van Dyk J, Wesolowska P, Hernandez V, Jornet N, Tomsej M, Bokulic T, Izewska J. IAEA methodology for on-site end-to-end IMRT/VMAT audits: an international pilot study. Acta Oncol 2020; 59:141-148. [PMID: 31746249 DOI: 10.1080/0284186x.2019.1685128] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Background: The IAEA has developed and tested an on-site, end-to-end IMRT/VMAT dosimetry audit methodology for head and neck cases using an anthropomorphic phantom. The audit methodology is described, and the results of the international pilot testing are presented.Material and methods: The audit utilizes a specially designed, commercially available anthropomorphic phantom capable of accommodating a small volume ion chamber (IC) in four locations (three in planning target volumes (PTVs) and one in an organ at risk (OAR)) and a Gafchromic film in a coronal plane for the absorbed dose to water and two-dimensional dose distribution measurements, respectively. The audit consists of a pre-visit and on-site phases. The pre-visit phase is carried out remotely and includes a treatment planning task and a set of computational exercises. The on-site phase aims at comparing the treatment planning system (TPS) calculations with measurements in the anthropomorphic phantom following an end-to-end approach. Two main aspects were tested in the pilot study: feasibility of the planning constraints and the accuracy of IC and film results in comparison with TPS calculations. Treatment plan quality was scored from 0 to 100.Results: Forty-two treatment plans were submitted by 14 institutions from 10 countries, with 79% of them having a plan quality score over 90. Seventeen sets of IC measurement results were collected, and the average measured to calculated dose ratio was 0.988 ± 0.016 for PTVs and 1.020 ± 0.029 for OAR. For 13 film measurement results, the average gamma passing rate was 94.1% using criteria of 3%/3 mm, 20% threshold and global gamma.Conclusions: The audit methodology was proved to be feasible and ready to be adopted by national dosimetry audit networks for local implementation.
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Affiliation(s)
| | - Wolfgang Lechner
- Department of Radiation Oncology, Division of Medical Physics, Medical University of Vienna, Vienna, Austria
- Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Vienna, Austria
| | | | - Catharine H. Clark
- Department of Medical Physics, Royal Surrey County Hospital, Guildford, UK
- Metrology for Medical Physics (MEMPHYS), National Physical Laboratory, Teddington, UK
| | | | - Jacob Van Dyk
- Department of Oncology and Medical Biophysics, Western University, London, Canada
| | | | - Victor Hernandez
- Department of Medical Physics, Hospital Sant Joan de Reus, IISPV, Tarragona, Spain
| | - Nuria Jornet
- Servei de Radiofisica i Radioproteccio, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Milan Tomsej
- CHU Charleroi, Hopital Andre Vesale, Montigny-le-Tilleul, Belgium
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Lye J, Kry S, Shaw M, Gibbons F, Keehan S, Lehmann J, Kron T, Followill D, Williams I. A comparison of IROC and ACDS on-site audits of reference and non-reference dosimetry. Med Phys 2019; 46:5878-5887. [PMID: 31494941 PMCID: PMC6916618 DOI: 10.1002/mp.13800] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 07/19/2019] [Accepted: 08/05/2019] [Indexed: 11/18/2022] Open
Abstract
PURPOSE Consistency between different international quality assurance groups is important in the progress toward similar standards and expectations in radiotherapy dosimetry around the world, and in the context of consistent clinical trial data from international trial participants. This study compares the dosimetry audit methodology and results of two international quality assurance groups performing a side-by-side comparison at the same radiotherapy department, and interrogates the ability of the audits to detect deliberately introduced errors. METHODS A comparison of the core dosimetry components of reference and non-reference audits was conducted by the Imaging and Radiation Oncology Core (IROC, Houston, USA) and the Australian Clinical Dosimetry Service (ACDS, Melbourne, Australia). A set of measurements were conducted over 2 days at an Australian radiation therapy facility in Melbourne. Each group evaluated the reference dosimetry, output factors, small field output factors, percentage depth dose (PDD), wedge, and off-axis factors according to their standard protocols. IROC additionally investigated the Electron PDD and the ACDS investigated the effect of heterogeneities. In order to evaluate and compare the performance of these audits under suboptimal conditions, artificial errors in percentage depth dose (PDD), EDW, and small field output factors were introduced into the 6 MV beam model to simulate potential commissioning/modeling errors and both audits were tested for their sensitivity in detecting these errors. RESULTS With the plans from the clinical beam model, almost all results were within tolerance and at an optimal pass level. Good consistency was found between the two audits as almost all findings were consistent between them. Only two results were different between the results of IROC and the ACDS. The measurements of reference FFF photons showed a discrepancy of 0.7% between ACDS and IROC due to the inclusion of a 0.5% nonuniformity correction by the ACDS. The second difference between IROC and the ACDS was seen with the lung phantom. The asymmetric field behind lung measured by the ACDS was slightly (0.3%) above the ACDS's pass (optimal) level of 3.3%. IROC did not detect this issue because their measurements were all assessed in a homogeneous phantom. When errors were deliberately introduced neither audit was sensitive enough to pick up a 2% change to the small field output factors. The introduced PDD change was flagged by both audits. Similarly, the introduced error of using 25° wedge instead of 30° wedge was detectible in both audits as out of tolerance. CONCLUSIONS Despite different equipment, approach, and scope of measurements in on-site audits, there were clear similarities between the results from the two groups. This finding is encouraging in the context of a global harmonized approach to radiotherapy quality assurance and dosimetry audit.
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Affiliation(s)
- Jessica Lye
- Australian Clinical Dosimetry ServiceARPANSAMelbourneAustralia
| | - Stephen Kry
- Imaging and Radiation Oncology Core Houston QA CenterMD Anderson Cancer CenterHoustonTXUSA
| | - Maddison Shaw
- Australian Clinical Dosimetry ServiceARPANSAMelbourneAustralia
| | - Francis Gibbons
- Australian Clinical Dosimetry ServiceARPANSAMelbourneAustralia
- Sunshine Coast Hospital and Health ServiceBirtinyaQldAustralia
| | | | - Joerg Lehmann
- Australian Clinical Dosimetry ServiceARPANSAMelbourneAustralia
- Department of Radiation OncologyCalvary Mater NewcastleNewcastleAustralia
| | - Tomas Kron
- Peter MacCallum Cancer CentreMelbourneAustralia
| | - David Followill
- Imaging and Radiation Oncology Core Houston QA CenterMD Anderson Cancer CenterHoustonTXUSA
| | - Ivan Williams
- Australian Clinical Dosimetry ServiceARPANSAMelbourneAustralia
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