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Kwon NH, Jang YJ, Yu S, Lee H, Choi DH, Ahn SH, Kim KB, Kim JS, Kim DW, Choi SH. Assessment of radio-activation using spectroscopy in medical linear accelerators. PLoS One 2024; 19:e0301435. [PMID: 38635642 PMCID: PMC11025788 DOI: 10.1371/journal.pone.0301435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 03/16/2024] [Indexed: 04/20/2024] Open
Abstract
In radiotherapy, when photon energy exceeding 8 MV is utilized, photoneutrons can activate the components within the gantry of the linear accelerator (linac). At the end of the linac's lifecycle, radiation workers are tasked with its dismantling and disposal, potentially exposing them to unintentional radiation. This study aims to identify and measure the radioisotopes generated by this activation through spectroscopy, and to evaluate the effective dose rate. We selected nine medical linacs, considering various factors such as manufacturer (Siemens, Varian, and Elekta), model, energy, period of operation, and workload. We identified the radionuclides in the linac head by employing an in situ high-purity germanium (HPGe) detector. Spectroscopy and dose-rate measurements were conducted post-shutdown. We also measured the dose rates at the beam-exit window following irradiation with 10 MV and 15 MV photon beams. As a result of the spectroscopy, we identified approximately 20 nuclides including those with half-lives of 100 days or longer, such as 54Mn, 60Co, 65Zn, 122Sb, and 198Au. The dose rate measurements after 10 MV irradiation decreased to the background level in 10 min. By contrast, on 15 MV irradiation, the dose rate was 628 nSv/h after 10 min and decreased to 268 nSv/h after 1.5 hours. It was confirmed that the difference in the level of radiation and the type of nuclide depends on the period of use, energy, and workload. However, the type of nuclide does not differ significantly between the linacs. It is necessary to propose appropriate guidelines for the safety of workers, and disposal/move-install should be planned while taking into consideration the equipment's energy usage rate.
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Affiliation(s)
- Na Hye Kwon
- Department of Radiation Oncology, Yonsei Cancer Center, Heavy Ion Therapy Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Young Jae Jang
- Department of Accelerator Science, Korea University, Sejong, Republic of Korea
- Research Team of Radiological Physics and Engineering, Korea Institute of Radiological and Medical Sciences, Seoul, Republic of Korea
| | - Suah Yu
- Research Team of Radiological Physics and Engineering, Korea Institute of Radiological and Medical Sciences, Seoul, Republic of Korea
- Department of Radiological Science, Kangwon National University, Samcheock, Republic of Korea
| | - Hanjin Lee
- Department of Radiological Emergency Preparedness, Korea Institute of Nuclear Safety, Daejeon, Republic of Korea
| | - Dong Hyeok Choi
- Department of Radiation Oncology, Yonsei Cancer Center, Heavy Ion Therapy Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - So Hyun Ahn
- Ewha Medical Research Institute, School of Medicine, Ewha Womans University, Seoul, Republic of Korea
| | - Kum Bae Kim
- Research Team of Radiological Physics and Engineering, Korea Institute of Radiological and Medical Sciences, Seoul, Republic of Korea
| | - Jin Sung Kim
- Department of Radiation Oncology, Yonsei Cancer Center, Heavy Ion Therapy Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
- Oncosoft Inc., Seoul, Republic of Korea
| | - Dong Wook Kim
- Department of Radiation Oncology, Yonsei Cancer Center, Heavy Ion Therapy Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Sang Hyoun Choi
- Research Team of Radiological Physics and Engineering, Korea Institute of Radiological and Medical Sciences, Seoul, Republic of Korea
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Alghamdi AAA. MCNPX Estimation of Photoneutron Dose to Eye Voxel Anthropomorphic Phantom From 18 MV Linear Accelerator. Dose Response 2023; 21:15593258231169807. [PMID: 37077717 PMCID: PMC10107973 DOI: 10.1177/15593258231169807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 03/27/2023] [Indexed: 04/21/2023] Open
Abstract
The dose due to photoneutron contamination outside the field of irradiation can be significant when using high-energy linear accelerators. The eye is a radiation-sensitive organ, and this risk increases when high linear energy transfer neutron radiation is involved. This study aimed to provide a fast method to estimate photoneutron dose to the eye during radiotherapy. A typical high-energy linear accelerator operating at 18 MV was simulated using the Monte Carlo N-Particle Transport Code System extended version (MCNPX 2.5.0). The latest International Atomic Energy Agency photonuclear data library release was integrated into the code, accounting for the most known elements and isotopes used in typical linear accelerator construction. The photoneutron flux from a 5 × 5 cm2 field size was scored at the treatment table plane and used as a new source for estimating the absorbed dose in a high-resolution eye voxel anthropomorphic phantom. In addition, common shielding media were tested to reduce the photoneutron dose to the eye using common shielding materials. Introducing a 2 cm thickness of common neutron shielding medium reduced the total dose received in the eye voxel anthropomorphic phantom by 54%. In conclusion, individualized treatment based on photoneutron dose assessment is essential to better estimate the secondary dose inside or outside the field of irradiation.
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Affiliation(s)
- Ali AA Alghamdi
- Department of Radiological
Sciences, College of Applied Medical Science, Imam Abdulrahman Bin Faisal
University, Dammam, Saudi Arabia
- Ali AA Alghamdi, Department of Radiological
Sciences, College of Applied Medical Science, Imam Abdulrahman Bin Faisal
University, P.O. Box 2435, Dammam, Saudi Arabia 31441.
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3
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Kwon NH, Shin DO, Kim J, Yoo J, Park MS, Kim KB, Kim DW, Choi SH. Current status of disposal and measurement analysis of radioactive components in linear accelerators in Korea. NUCLEAR ENGINEERING AND TECHNOLOGY 2022. [DOI: 10.1016/j.net.2021.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Wang H, Chen K, Shi Y, Huang X, Sun W, Hou K, Jin Y, Jiang X, Yang D, Dong L. Technical Note: Induced radioactivity in stereotactic body radiation therapy with a flattening-filter-free 10 MV beam model. Med Phys 2021; 48:2010-2017. [PMID: 33524168 DOI: 10.1002/mp.14747] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 11/11/2020] [Accepted: 01/25/2021] [Indexed: 01/03/2023] Open
Abstract
PURPOSE The induced radioactivity in stereotactic body radiation therapy with a flattening-filter-free 10 MV beam model (10 FFF SBRT) was investigated for the risk to therapists. METHODS This study was performed on a Varian TrueBeam linac. The induced radioisotopes were identified by γ spectroscopy. The dose rate from the induced activity was measured for 12 treatment cycles in 4 h continuously. The impacts of the characteristic factors of 10 FFF SBRT on the dose rate were investigated, including monitor units (MU), beam rate, field size, and flattening filter. The dose rate was compared between the SBRT plans and conventional fractionation plans. A mathematical model was used to analyze the results and estimate the annual dose to therapists. RESULTS (a) The induced radioisotopes included 24 Na, 28 Al, 38 Cl, 56 Mn, 66 Cu, 187 W, and 196 Au. (b) In 4 h, the total dose contribution ratios were more than 70% for 28 Al, about 20% for 56 Mn, and 10% for all other long-lived radioisotopes, combining doses at the isocenter and end of the treatment couch. (c) The dose rate showed a nonlinear growth with increasing MU and beam rate. The variation of the dose rate was complicated with the jaw field and not sensitive to the MLC field. The removal of the flattening filter reduced the dose rate by about 40%. The dose level of SBRT was two to three times that of conventional fractionation. (d) The estimated annual dose to therapists was up to 0.20 mSv/y. CONCLUSIONS The induced radioactivity in 10 FFF SBRT was higher compared with that in 10 MV conventional fractionation. More MU and higher beam rate were the primary factors that caused the increase. The therapists should wait longer after beam-off to reduce the occupational dose. In addition, aluminum and manganese should be less used in the treatment room.
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Affiliation(s)
- Huidong Wang
- Department of Radiation Oncology & Therapy, The First Hospital of Jilin University, Changchun, China
| | - Kunzhi Chen
- Department of Radiation Oncology & Therapy, The First Hospital of Jilin University, Changchun, China
| | - Yinghua Shi
- Department of Radiation Oncology & Therapy, The First Hospital of Jilin University, Changchun, China
| | | | - Wuji Sun
- College of Physics, Jilin University, Changchun, China
| | - Kairan Hou
- College of Physics, Jilin University, Changchun, China
| | - Yongli Jin
- China Institute of Atomic Energy, Beijing, China
| | - Xin Jiang
- Department of Radiation Oncology & Therapy, The First Hospital of Jilin University, Changchun, China
| | - Dong Yang
- College of Physics, Jilin University, Changchun, China
| | - Lihua Dong
- Department of Radiation Oncology & Therapy, The First Hospital of Jilin University, Changchun, China.,Jilin Provincial Key Laboratory of Radiation Oncology & Therapy, The First Hospital of Jilin University, Changchun, China
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5
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Montgomery L, Evans M, Liang L, Maglieri R, Kildea J. The effect of the flattening filter on photoneutron production at 10 MV in the Varian TrueBeam linear accelerator. Med Phys 2018; 45:4711-4719. [PMID: 30141186 DOI: 10.1002/mp.13148] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 07/25/2018] [Accepted: 08/08/2018] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Neutrons are an unavoidable by-product of high-energy radiation therapy treatments that deliver unwanted nontarget dose to patients. Use of flattening-filter-free (FFF) photon beams has been shown to significantly reduce photoneutron production per monitor unit (MU) of dose delivered. The purpose of this investigation was to characterize the photoneutron production of the 10 MV and 10 MV FFF beams of the Varian TrueBeamTM linear accelerator. METHODS Neutron fluence spectra were measured using a Nested Neutron SpectrometerTM (NNS, Detec Inc., Gatineau, Canada). The ratios of neutron fluence and ambient dose equivalent for the 10 MV FFF beam relative to the 10 MV beam, dubbed FF-ratios (FFF/FF), were used to characterize the difference between the two beams. FF-ratios were compared under the following three conditions (a) per MU, at various locations in the treatment room, (b) per MU, with the linac jaws opened and closed, and (c) per electron striking the bremsstrahlung target, as opposed to per MU, at one location with the jaws closed. RESULTS On average, the neutron fluence for the 10 MV FFF beam was 37% lower per MU than the 10 MV beam (FF-ratio = 0.63). The FF-ratio in neutron fluence and ambient dose equivalent did not vary by much between different locations within the treatment room. However, the FF-ratio in neutron ambient dose equivalent was reduced significantly when the linac jaws were opened compared to closed, which implies that the jaws contribute more to the photoneutron spectrum of the 10 MV FFF beam than to the 10 MV beam. Finally, it was found that the 10 MV FFF beam produces more photoneutrons per electron striking the bremsstrahlung target than the 10 MV beam (FF-ratio = 2.56). CONCLUSIONS The photoneutron fluence per MU produced by the 10 MV FFF beam is 37% lower than the 10 MV beam of a Varian TrueBeam linac. Accordingly, a reduction in neutron dose received by patients is achieved through use of the unflattened beam, provided that treatment plans for each beam require approximately the same number of MU. It was found to be instructive to compare the photoneutron yield per source electron between the two beams as it helped provide an understanding of the physics underlying photoneutron production in both beams.
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Affiliation(s)
- Logan Montgomery
- Medical Physics Unit, McGill University, Montreal, QC, H4A3J1, Canada
| | - Michael Evans
- Medical Physics Unit, McGill University, Montreal, QC, H4A3J1, Canada
| | - Liheng Liang
- Medical Physics Unit, McGill University, Montreal, QC, H4A3J1, Canada.,Department of Radiation Oncology, Jewish General Hospital, Montreal, QC, H3T1E2, Canada
| | - Robert Maglieri
- Medical Physics Unit, McGill University, Montreal, QC, H4A3J1, Canada
| | - John Kildea
- Medical Physics Unit, McGill University, Montreal, QC, H4A3J1, Canada
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6
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Nourmohammadi B, Mesbahi A. A REVIEW ON THE RADIATION THERAPY TECHNOLOGIST RECEIVED DOSE FROM INDUCED ACTIVATION IN HIGH-ENERGY MEDICAL LINEAR ACCELERATORS. RADIATION PROTECTION DOSIMETRY 2018; 179:333-348. [PMID: 29309661 DOI: 10.1093/rpd/ncx292] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 12/02/2017] [Indexed: 06/07/2023]
Abstract
Despite all advantages for using high-energy photons for radiotherapy, high-energy photon beams (≥10 MV) induce photonuclear and neutron capture interactions, which result in producing radionuclide byproducts inside the Linac head and bunker, exposing radiation therapy technologists (RTTs) and patients to excessive dose. By the use of higher photon energy, greater number of monitor unit, greater field size and adding treatment accessories, induced dose rate become greater in the isocenter mainly due to activation of high-Z materials inside the Linac head. Activated radionuclides disintegrate with γ, β+ and β- rays with half-lives between 2 min up to more than 5 years. Several researches estimated additional exposure to an RTT depend on treatment strategies, beam energy, and delay time before entrance to the treatment room between 0.1 and 4.9 mSv/y and proposed at least 2 min delay before entrance to the treatment room after treatments with high-energy photon beams.
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Affiliation(s)
- Bahareh Nourmohammadi
- Medical Radiation Sciences Research Team, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Medical Physics, Medical School, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Asghar Mesbahi
- Medical Radiation Sciences Research Team, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Medical Physics, Medical School, Tabriz University of Medical Sciences, Tabriz, Iran
- Molecular Medicine Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
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7
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Waller E, Ram R, Steadman I. Preliminary Determination of Activation Products for a Varian Truebeam Linear Accelerator. HEALTH PHYSICS 2017; 113:227-233. [PMID: 28749813 DOI: 10.1097/hp.0000000000000693] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Medical linear accelerators used to treat various forms of cancers are operated at a number of different energies. A by-product of the high-energy photons produced by accelerators is activation of components within the machine itself and its surrounding bunker. The activation products pose radiological and regulatory challenges during the operation of the accelerator as well as when it is time for final decommissioning. The Varian TrueBeam is a new state-of-the-art linear accelerator now operating in the Canadian market. There is currently limited information on the production of its activation products and the resulting impacts on operation and decommissioning. In this paper, activation products in the Varian TrueBeam accelerator are experimentally determined by performing gamma spectroscopy using a portable high purity germanium detector. A total of 10 isotopes are identified for the conditions tested, which include Na, Al, Mn, Ni, Cu, Cu, Br, Sb, Sb, W. The half-lives of these isotopes range from 2.3 min to 60.2 d. These preliminary results indicate that a decommissioning case similar to other radiotherapy accelerators can be made.
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Affiliation(s)
- Edward Waller
- *University of Ontario Institute of Technology, Faculty of Energy Systems and Nuclear Science Oshawa, Ontario Canada
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8
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Han B, Bednarz B, Danon Y, Block R, Xu XG. Evaluation of Nuclear Activation of Tungsten Plates for Future Modeling of a Medical Accelerator. NUCL TECHNOL 2017. [DOI: 10.13182/nt09-a9246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Bin Han
- Rensselaer Polytechnic Institute Nuclear Engineering and Engineering Physics, Troy, New York 12180
| | - Bryan Bednarz
- Rensselaer Polytechnic Institute Nuclear Engineering and Engineering Physics, Troy, New York 12180
| | - Yaron Danon
- Rensselaer Polytechnic Institute Nuclear Engineering and Engineering Physics, Troy, New York 12180
| | - Robert Block
- Rensselaer Polytechnic Institute Nuclear Engineering and Engineering Physics, Troy, New York 12180
| | - X. George Xu
- Rensselaer Polytechnic Institute Nuclear Engineering and Engineering Physics, Troy, New York 12180
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9
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Keehan S, Taylor ML, Smith RL, Dunn L, Kron T, Franich RD. DOSE AND GAMMA-RAY SPECTRA FROM NEUTRON-INDUCED RADIOACTIVITY IN MEDICAL LINEAR ACCELERATORS FOLLOWING HIGH-ENERGY TOTAL BODY IRRADIATION. RADIATION PROTECTION DOSIMETRY 2016; 172:327-332. [PMID: 26598738 DOI: 10.1093/rpd/ncv480] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 10/15/2015] [Accepted: 10/17/2015] [Indexed: 06/05/2023]
Abstract
Production of radioisotopes in medical linear accelerators (linacs) is of concern when the beam energy exceeds the threshold for the photonuclear interaction. Staff and patients may receive a radiation dose as a result of the induced radioactivity in the linac. Gamma-ray spectroscopy was used to identify the isotopes produced following the delivery of 18 MV photon beams from a Varian 21EX and an Elekta Synergy. The prominent radioisotopes produced include 187W, 63Zn, 56Mn, 24Na and 28Al in both linac models. The dose rate was measured at the beam exit window (12.6 µSv in the first 10 min) following 18 MV total body irradiation (TBI) beams. For a throughput of 24 TBI patients per year, staff members are estimated to receive an annual dose of up to 750 μSv at the patient location. This can be further reduced to 65 μSv by closing the jaws before re-entering the treatment bunker.
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Affiliation(s)
- S Keehan
- School of Applied Sciences, RMIT University, Melbourne, Australia
| | - M L Taylor
- School of Applied Sciences, RMIT University, Melbourne, Australia
| | - R L Smith
- School of Applied Sciences, RMIT University, Melbourne, Australia
- William Buckland Radiotherapy Centre, Alfred Hospital, Melbourne, Australia
| | - L Dunn
- Australian Clinical Dosimetry Service, ARPANSA, Yallambie, Australia
| | - T Kron
- School of Applied Sciences, RMIT University, Melbourne, Australia
- Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne, Australia
| | - R D Franich
- School of Applied Sciences, RMIT University, Melbourne, Australia
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10
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Watanabe H, Maehara Y, Fujibuchi T, Koizumi M, Yamaguchi I, Kida T, Ooyama M, Horitsugi G, Hiraki H, Tsukamoto A, Itami J. Assessing the Effectiveness of Risk Communication for Maintenance Workers Who Deal With Induced Radioactivity Management of Medical Linear Accelerators. HEALTH PHYSICS 2015; 109:145-156. [PMID: 26107435 DOI: 10.1097/hp.0000000000000306] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In Japan, an amended law that mandates levels of unintended induced radioactivity has been in effect since 1 April 2012. According to the new regulation, if the concentration of induced radioactivity in affected parts is above the clearance level, the parts must be regarded as radioactive even if they weigh less than 1 kg. This regulation reform raises several new issues concerning medical linear accelerators, including how to determine the decay period for induced radioactivity before maintenance can be performed and how to identify what parts should be considered radioactive waste. The authors performed several risk communication (RC) activities aimed at improving the understanding of maintenance workers at medical accelerator manufacturers and establishing good guidelines by involving stakeholders. For this purpose, a working group was established and conducted RC activities, such as holding opinion exchange meetings between medical staff and maintenance workers and creating a booklet to answer questions from maintenance workers. To evaluate these activities, three questionnaire surveys were conducted between 2011 and 2014. According to the results of this study, the ratio of maintenance workers who accepted "The decay period is within one week" was approximately 60% at the third survey and significantly increased (P < 0.0001) during the survey period. Approximately 25% of the maintenance workers felt that not enough information was provided about the decay period, and approximately 63% thought that the information provided on the health effects of radiation was sufficient. These results suggest that the present RC was successful.
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Affiliation(s)
- Hiroshi Watanabe
- *Department of Radiological Technology, Japan Labour Health and Welfare Organization Yokohama Rosai Hospital, 3211, Kozukue-chou, Kohoku-ku, Yokohama-city, Kanagawa, Japan; †Graduate School of Health Science, Suzuka University of Medical Science, 1001-1, Kishioka-chou Suzuka, Mie 510-0293, Japan; ‡Imaging Center, ST. Marianna University School of Medicine Hospital, 2-16-1, Sugao, Miyamae, Kawasaki, Kanagawa 216-8511, Japan; §Medical Quantum Science, Department of Health Sciences, Faculty of Medical Sciences, Graduate School of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka, Japan; **Diagnostic Imaging, Kawasaki Municipal Tama Hospital, 1-30-37, Syukugawara, Tama-ku, Kawasak-cityi, Kanagawa 214-8525, Japan; ††Department of Environmental Health, National Institute of Public Health, 2-3-6, Minami, Wako-city, Saitama 351-0197, Japan; ‡‡Department of Radiology Service, Shiga University of medical Science Hospital, Setatsukinowa-chou, Ootsu-city, Shiga 520-2192, Japan; §§Department of Radiology, National Hospital Organization Chiba East Hospital, 673, Nitona-cyo, Cyuou-ku, Chiba-city, Chiba 260-8712, Japan; ***Department of Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka, Japan; †††Department of Radiological Technology, Teikyo University School of Medicine, University Hospital, Mizonokuchi, 3-8-3, Mizonokuchi, Takatsu-ku, Kawasaki City, Kanagawa 213-8507, Japan; ‡‡‡Department of Radiology, NTT Medical Center Tokyo, 5-9-22, Higashi-Gotannda, Shinagawa-ku, Tokyo 141-8625, Japan; §§§Department of Radiation Oncology, National Cancer Center Hospital, Tsukiji 5-1-1, Chuo-ku, Tokyo, Japan
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11
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Induced radioisotopes in a linac treatment hall. Appl Radiat Isot 2015; 102:103-108. [DOI: 10.1016/j.apradiso.2015.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Revised: 05/10/2015] [Accepted: 05/10/2015] [Indexed: 11/19/2022]
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12
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Saeed MK, Poppe B, Fischer HW. Direct air activation measurements at a 15-MV medical linear accelerator. RADIATION PROTECTION DOSIMETRY 2015; 163:233-237. [PMID: 24795383 DOI: 10.1093/rpd/ncu149] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Direct radiometric determination of (14)N (γ, n) (13)N air activation was achieved at a 15-MV medical linear accelerator operating in a high-energy photon mode. (13)N was identified by irradiating a gas-tight Marinelli beaker filled with nitrogen gas and later observing the 10-min half-life of the 511-keV positron-electron annihilation line using high-resolution gamma spectroscopy. Quantitative evaluation of the spectral signal yielded a (13)N production rate of 836.8 ± 32 Bq Gy(-1) in air per 40 × 40 cm(2) field cross section at 100 cm source-surface distance.
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Affiliation(s)
- M K Saeed
- Physics Department, University of Bremen, Bremen 28359, Germany
| | - B Poppe
- Physics Department, University of Oldenburg, Oldenburg 26111, Germany
| | - H W Fischer
- Physics Department, University of Bremen, Bremen 28359, Germany
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13
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Yonekura Y, Tsujii H, Hopewell JW, López PO, Cosset JM, Paganetti H, Montelius A, Schardt D, Jones B, Nakamura T. ICRP Publication 127: Radiological Protection in Ion Beam Radiotherapy. Ann ICRP 2014; 43:5-113. [PMID: 25915952 DOI: 10.1177/0146645314559144] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The goal of external-beam radiotherapy is to provide precise dose localisation in the treatment volume of the target with minimal damage to the surrounding normal tissue. Ion beams, such as protons and carbon ions, provide excellent dose distributions due primarily to their finite range, allowing a significant reduction of undesired exposure of normal tissue. Careful treatment planning is required for the given type and localisation of the tumour to be treated in order to maximise treatment efficiency and minimise the dose to normal tissue. Radiation exposure in out-of-field volumes arises from secondary neutrons and photons, particle fragments, and photons from activated materials. These unavoidable doses should be considered from the standpoint of radiological protection of the patient. Radiological protection of medical staff at ion beam radiotherapy facilities requires special attention. Appropriate management and control are required for the therapeutic equipment and the air in the treatment room that can be activated by the particle beam and its secondaries. Radiological protection and safety management should always conform with regulatory requirements. The current regulations for occupational exposures in photon radiotherapy are applicable to ion beam radiotherapy with protons or carbon ions. However, ion beam radiotherapy requires a more complex treatment system than conventional radiotherapy, and appropriate training of staff and suitable quality assurance programmes are recommended to avoid possible accidental exposure of patients, to minimise unnecessary doses to normal tissue, and to minimise radiation exposure of staff.
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14
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Watanabe H, Yamaguchi I, Maehara Y, Koizumi M, Fujibuchi T, Kida T, Tsukamoto A, Horitsugi G, Hiraki H, Kimura Y, Oyama M. [Evaluation of a risk communication approach for maintenance staff working with induced radioactivity in medical linear accelerators]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2013; 69:1353-62. [PMID: 24366555 DOI: 10.6009/jjrt.2013_jsrt_69.12.1353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In order to promote consensus building on decommissioning operation rules for medical linear accelerators in Japan, we carried out a risk communication (RC) approach mainly providing knowledge for maintenance staff regarding induced radioactivity. In February 2012, we created a booklet (26 pages) to present an overview of the amended law, the mechanism and the distribution of induced radioactivity showing the actual radiation dose rate around a linear accelerator and actual exposure doses to staff. In addition, we co-sponsored a seminar for workers in this field organized by the Japan Medical Imaging and Radiological Systems Industries Association to explain the contents of this booklet, and answer questions regarding induced radioactivity of linear accelerators as an RC program. As a result, the understanding of staff regarding the regulations on maximum X-ray energy on linear accelerators (P<0.05), and the outline of clearance systems (P<0.01), were facilitated by RC. In addition, we found that about 70% of maintenance staff considered that the cooling time for decommissioning operation depended on the situation. Our RC approach suggests that consensus building should be used to make rules on decommissioning operations for linear medical accelerators.
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15
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Ho L, White P, Chan E, Chan K, Ng J, Tam T. Evaluation of Optimum Room Entry Times for Radiation Therapists after High Energy Whole Pelvic Photon Treatments. J Occup Health 2012; 54:131-40. [DOI: 10.1539/joh.11-0161-fs] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Lavine Ho
- Department of Health Technology and InformaticsThe Hong Kong Polytechnic UniversityHong Kong
| | - Peter White
- Department of Health Technology and InformaticsThe Hong Kong Polytechnic UniversityHong Kong
| | - Edward Chan
- Department of Health Technology and InformaticsThe Hong Kong Polytechnic UniversityHong Kong
| | - Kim Chan
- Department of Health Technology and InformaticsThe Hong Kong Polytechnic UniversityHong Kong
| | - Janet Ng
- Department of Health Technology and InformaticsThe Hong Kong Polytechnic UniversityHong Kong
| | - Timothy Tam
- Department of Health Technology and InformaticsThe Hong Kong Polytechnic UniversityHong Kong
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Fujibuchi T, Obara S, Yamaguchi I, Oyama M, Watanabe H, Sakae T, Katoh K. Induced radioactive nuclides of 10-MeV radiotherapy accelerators detected by using a portable HP-Ge survey meter. RADIATION PROTECTION DOSIMETRY 2012; 148:168-173. [PMID: 21317145 DOI: 10.1093/rpd/ncr005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The radioactivation of linear accelerator components for radiation therapy is interest for radiation protection in general, and particularly, when decommissioning these structures. The energy spectra of gamma rays emitted from the heads of two accelerator models, EXL-15SP and Clinac iX, after 10-MeV X-ray irradiation, were measured using a high-purity germanium semiconductor survey meter. After spectrum analyses, activities of (24)Na, (28)Al, (54)Mn, (56)Mn, (57)Ni, (58)Co, (60)Co, (64)Cu, (65)Zn, (122)Sb, (124)Sb, (181)W, (187)W, (196)Au, and (198)Au were detected. One centimetre deep dose-equivalent rate of the heads of the linear accelerator was measured using the survey meter. The dose rate decreased to ∼10 % of its initial rate after 1 week. Long-term activations were few, the radioactivity level was low, and a cooling time of several days was effective for reducing dose rate to an acceptable level for decommissioning.
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Affiliation(s)
- Toshioh Fujibuchi
- Department of Radiological Sciences, School of Health Sciences, Ibaraki Prefectural University of Health Science, 4669-2 Ami, Ami-machi, Inashiki-gun, Ibaraki 300-0394, Japan
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Kalef-Ezra JA. Health physics aspects in treatment rooms after 18-MV X-ray irradiations. RADIATION PROTECTION DOSIMETRY 2011; 147:281-286. [PMID: 21979431 DOI: 10.1093/rpd/ncr361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Delayed activation products contribute to the exposure of the staff operating high-energy accelerators. Induced activity was studied in a treatment room following 18-MV X-ray irradiations using a hand-held system that allows both dose rate measurements and spectroscopic analysis. The major activation products and the corresponding nuclear reactions were identified. At the majority of the studied locations, β(+) emitters were the main short-term dose contributors. The time variation of the absorbed dose rate in a treatment room during the first 20-min post-irradiation was represented by the sum of two exponential components with half-lives of 1-2 min and either 4 or 10 min, depending on the location in the room. Components with a half-life of hours or days contribute <1 % to the initial dose rate. The activation of some accessories, such as iron filters and portal imagers, deserve special attention. The collection of such data with the proposed method allows the development of optimised working protocols at each treatment room.
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Affiliation(s)
- John A Kalef-Ezra
- Medical Physics Department, University of Ioannina and Ioannina University Hospital, 45510 Ioannina, Greece.
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Watanabe H, Fujibuch T, Yamaguchi I. [Role of academic societies in standardization activities of waste management of induced radioactivity in therapeutic accelerators]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2011; 67:581-586. [PMID: 21666383 DOI: 10.6009/jjrt.67.581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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Petrović N, Krestić-Vesović J, Stojanović D, Ciraj-Bjelac O, Lazarević D, Kovacević M. Contribution of activation products to occupational exposure following treatment using high-energy photons in radiotherapy. RADIATION PROTECTION DOSIMETRY 2011; 143:109-112. [PMID: 20947589 DOI: 10.1093/rpd/ncq290] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
When high-energy photon beams are used for irradiation in radiotherapy, neutrons that are the result of photonuclear reactions create activation products that affect the occupational dose of radiotherapy staff. For the assessment of activation products in situ gamma spectroscopy was performed parallel to dose-rate measurements following irradiation, by using a high-energy photon beam from a linear accelerator Elekta Precise (Elekta, Stockholm, Sweden) used in radiotherapy. The major identified activation products were the following radioisotopes: (28)Al, (24)Na, (56)Mn, (54)Mn, (187)W, (64)Cu and (62)Cu. Based on the typical workload and dose-rate measurement, the assessed additional annual occupational dose ranged from 1.7 to 0.25 mSv. As the measured dose rate arising from the activation products rapidly decreases as a function of time, the assessed additional dose is negligible after 10 min following irradiation. To keep the occupational dose as low as reasonably achievable, it is recommended to delay entrance to the therapy room at least 2-4 min, when high-energy photons are used. This would reduce the effective dose by 30%.
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Fukuma H, Eguchi Y, Isoyama S, Kawano M, Suzuki Y, Aoyama T, Kato H. [Analysis of photonuclear activation effect of high-energy medical linear accelerators--measurement of spatial dose distribution and temporal decay curve, and assessment of personnel dosimetry]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2010; 66:495-501. [PMID: 20628217 DOI: 10.6009/jjrt.66.495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The characteristics of activation after high-energy X-rays have been generated by medical linear accelerators were measured using an ionization chamber. Radiation doses increased with rising X-ray energy, based on 10 MV, 15 MV, and 18 MVX-ray measurements. When the total irradiation dose was changed, radiation dose increased with total irradiation dose. When the collimator opened, the radiation dose at a position 15 cm from the isocenter reached about the maximum, which was 2.2 times the dose at the isocenter. The radiation dose became about 0.3 times its level at a position 40 cm from the isocenter, in the outer irradiation field. The dose distribution in the treatment room became almost the same dose extending from the isocenter to 200 cm. Radiation dose decreased gradually while moving away from the target on the treatment beam axis. But it increased again as it approached the floor face. The occupational exposure dose, which was presumed from measurements of the radiation dose 50 cm from the isocenter, was about 0.9 mSv during a year, assuming 600 MU for 1 person, 8 people a day, and 245 days a year. Radiation dose changed with X-ray energy in the machine used, and it was a geometrical constituent in the treatment room. It is important to understand the characteristics of radiation generated by medical linear accelerators.
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Affiliation(s)
- Hiroshi Fukuma
- Central Department of Radiology, Nagoya City University Hospital
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Vega-Carrillo HR, Hernández-Almaraz B, Hernández-Dávila VM, Ortíz-Hernández A. Neutron spectrum and doses in a 18 MV LINAC. J Radioanal Nucl Chem 2009. [DOI: 10.1007/s10967-009-0337-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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