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| Absolute Measurement and International Comparison of Absorbed Dose to Water for Accelerator Photon Beams by Water Calorimeter |
| WANG Kun,ZHANG Jian,WANG Zhi-peng,JIN Sun-jun,YANG Xiao-yuan,LIU Fu-bin |
| National Institute of Metrology, Beijing 100029, China |
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Abstract A water calorimeter was developed for conducting the absolute measurement of the absorbed dose to water of the photon beams from accelerator, followed by obtaining the international mutual recognition and establishing the primary standard for absorbed dose to water of the photo beams from accelerator and improving the dissemination for radiotherapy in China. The temperature drift of water phantom of the calorimeter was maintained at 0.5μ℃/s by the bath and Peltier cooling system. The resistance of thermistors caused by radiation was measured by Wheatstone AC bridge. After calibrating thermistors and the bridge separately,the absorbed dose to water of photon beams from accelerator was reproduced with the uncertainty of 0.30%. The key comparison on the absorbed dose to water of the photon beams from accelerator was performed between NIM and BIPM. By considering the result of NIM as against the reference quantity of BIPM, the ratio for the 6MV and 10MV photon beams is 0.9917 and 0.9949 respectively, which is within the acceptance of uncertainty.
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Received: 31 March 2020
Published: 08 December 2020
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［1］Picard S, Burns D T, Roger P, et al. Comparison of the standards for absorbed dose to water of the NRC and the BIPM for accelerator photon beams ［J］. Metrologia, 2010, 47(Technical Supplement): 06025.
［2］Key comparison BIPM. RI (I)-K6. BIPM key Compa-rison Database, BIPM［EB/OL］. https://www. bipm. org/kcdb/.
［3］郞锦义, 王培, 吴大可, 等. 2015年中国大陆放疗基本情况调查研究 ［J］. 中华放射肿瘤学杂志, 2016, 25(6): 541-545.
Lang J Y, Wang P, Wu D K, et al. An investigation of the basic situation of radiotherapy in mainland China in 2015 ［J］. Chin J Radiat Oneol, 2016, 25(6): 541-545.
［4］王坤, 李涛, 杨小元. 60Co水吸收剂量的量值复现和国际比对验证 ［J］. 中国医学物理学杂志, 2013, 30(6): 4476-4479.
Wang K, Li T, Yang X Y. Reproduction and international comparison of absorbed dose to water in 60Co Radiation［J］. Chin J Med Phys, 2013, 30(6): 4476-4479.
［5］Muir B R, Cojocaru C D, Mcewen M R, et al. Electron beam water calorimetry measurements to obtain beam quality conversion factors ［J］. Med Phys, 2017, 44(10): 5433-5444.
［6］Krauss A, Kapsch R P. Experimental determination of kQ factors for cylindrical ionization chambers in 10cm×10cm and 3cm×3cm photon beams from 4MV to 25MV ［J］. Phys Med Biol, 2014, 59(15):4227-4246.
［7］De Prez L, De Pooter J, Jansen B, et al. A water calorimeter for on-site absorbed dose to water calibrations in 60Co and MV-photon beams including MRI incorporated treatment equipment ［J］. Phys Med Biol, 2016, 61(13): 5051-5076.
［8］Renaud J, Rossomme S, Sarfehnia A, et al. Development and application of a water calorimeter for the absolute dosimetry of short-range particle beams ［J］. Phys Med Biol, 2016, 61(18):6602-6619.
［9］Merwe D V D, Dyk J V, Healy B, et al. Accuracy requirements and uncertainties in radiotherapy: a report of the International Atomic Energy Agency ［J］. Acta Oncologica, 2016(1), 56: 1-6.
［10］Rogers D, Cygler J. Clinical Dosimetry Measure-ments in Radiotherapy ［C］//Proceedings of the Ameri-can Association of Physicists in Medicine. Colorado, USA, 2009.
［11］Seuntjens J P, Ross C K, Klassen N V, et al. A Status Report on the NRC Sealed Water Calorimeter PIR-S0584［R］. NRC, 1999.
［12］Medin J, Ross C K, Stucki G, et al. Commissi-oning of an NRC-type sealed water calorimeter at MET-AS using 60 Co-rays ［J］. Phys Med Biol, 2004, 49(17): 4073-4086.
［13］Krauss A. The PTB water calorimeter for the absolute determination of absorbed dose to water in 60Co radiation ［J］. Metrologia, 2006, 43(3): 259-272.
［14］Rapp B, Perichon N, Denoziere M, et al. The LNE-LNHB water calorimeter for primary measurement of absorbed dose at low depth in water: application to medium-energy x-rays ［J］. Phys Med Biol, 2013, 58(9): 2769-2786.
［15］De Prez L A, De Pooter J A, Jansen B J, et al. Commissioning of a water calorimeter as a primary stan-dard for absorbed dose to water in magnetic fields ［J］. Phys Med Biol, 2019, 64(3): 105025.
［16］Jin S, Wang K, Fan Y, et al. The reproduction for the absorbed-dose to water of the clinical accelerator photon beams ［J］. Phys Medica, 2016, 32(53):265-266.
［17］Picard S, Kessler C, Roger P, et al. Key comp-arison BIPM.RI (I)-K6 of the standards for absorbed dose to water at 10g·cm-2 of the NIM, China and the BIPM in accelerator photon beams ［J］. Metrologia, 2017, 54(1A): 06009.
［18］Muir B R, Cojocaru C D, Mcewen M R, et al. Electron beam water calorimetry measurements to obtain beam quality conversion factors ［J］. Med Phys, 2017, 44(10): 5433-5444.
［19］Seuntjens J, Palmans H. Correction factors and performance of a 4 degrees C sealed water calorimeter ［J］. Phys Med Biol, 1999, 44(3): 627-646.
［20］Harvey A, Peskin A, Klein S. NIST/ASME Steam Properties:NIST Standard Reference Database 10［R］. Gaithersburg, National Institute of Standards and Technology,1997.
［21］Kessler C, Burns D T, Picard S, et al. Comparison BIPM RI (I)-K6 of the standards for absorbed dose to water of the KRISS, Korea and the BIPM in accelerator photon beams ［J］. Metrologia, 2020, 57(1A): 06001.
［22］Shinizu M, Morishita Y, Kato M, et al. Comparison of the NMIJ and the ARPANSA standards for absorbed dose to water in high-energy photon beams ［J］. Radiat Prot Dosim, 2015, 164(3): 181-186.
［23］金孙均, 王志鹏, 王坤, 等. 60Co γ辐射的空气比释动能及水吸收剂量的NIM-IAEA双边比对 ［J］. 计量学报, 2016, 37 (4): 441-443.
Jin S J, Wang Z P, Wang K, et al. The NIM-IAEA Bilateral Comparison on the Air Kerma and Absorbed Dose to Water of 60Co γ Radiation ［J］. Acta Metrologica Sinica, 2016, 37 (4): 441-443.
［24］王志鹏, 王坤, 金孙均, 等. 医用加速器高能光子束水吸收剂量测量及不确定度分析 ［J］. 计量学报, 2019, 40 (6): 1124-1128.
Wang Z P, Wang K, Jin S J, et al. Measurement and Uncertainty Analysis of Absorbed Dose to Water of High-energy Photons in Medical Accelerator ［J］. Acta Metrologica Sinica, 2019, 40 (6): 1124-1128. |
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2020, Vol. 41 
