|
|
Measurements of Absorbed Dose to Water in Medical Electron Beams and Discussion of Its Uncertainty |
WANG Zhi-peng,WANG Kun,JIN Sun-jun,YANG Xiao-yuan,QI Ya-ping,HUANG Ji,LIU Fu-bin |
National Institute of Metrology, Beijing 100029, China |
|
|
Abstract The measurement uncertainty of absorbed dose to water, Dw, in medical electron beams exceeds 3%, which is difficult to meet the requirements of clinical treatment and verification regulation of medical electron accelerator radiation source. The research on measuring electron beam radiation dosimetry using water calorimetry was carried out by the National Institute of Metrology (NIM), which realized the direct measurement of the Dw, with a relative standard uncertainty of 0.35%. At the same time, the research on the homogenous traceability of medical electron beams have also been carried out. Five schemes for measuring the absorbed dose to water in electron beams have been summarized. The relative standard uncertainty includes the highest 3.7% and the lowest 1.4%. In order to facilitate the measurement of the Dw in clinical electron beams, some suggestions on the selection and calibration methods of ionization chambers were provided, and precautions for different calibration coefficients were emphasized.
|
Received: 29 December 2022
Published: 27 December 2023
|
|
Fund:The National Key Technologies R&D Program of China |
|
|
|
[1] |
Picard S, Kessler C, Roger P, et al. Key comparison 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) S1-26.
|
[2] |
王坤, 张健, 王志鹏, 等. 水量热法加速器光子水吸收剂量绝对测量与国际比对 [J]. 计量学报,2020,41(12):1552-1558.
|
[3] |
王坤, 金孙均, 王志鹏, 等. 医用加速器光子水吸收剂量量值体系的研究与应用 [J]. 中国计量,2019(7):77-80.
|
[4] |
Wang Z P, Xing S M, Wang K, et al. Direct measurement of ionization chamber absorbed dose kQ factors in clinical electron beams [J]. Radiation Measurements, 2020, 139(1):1-7.
|
[6] |
Smilowitz J B, Das I J, Feygelman V, et al. AAPM Medical Physics Practice Guideline 5.a.: Commissioning and QA of Treatment Planning Dose Calculations-Megavoltage Photon and Electron Beams [J]. Journal of Applied Clinical Medical Physics, 2015, 16(5):14-34.
|
[9] |
International Atomic Energy Agency. The use of plant parallel ionization chambers in high energy electron and photon beams:An International Code of Practice Technical Report Series No. 277[R].1997.
|
[10] |
Seltzer S M, Fernandez-Varea J M, Andreo P, et al. Key data for ionizing-radiation dosimetry: measurement standards and applications: ICRU Report 90 [R]. 2016.
|
[12] |
JJF 1743—2019 放射治疗用电离室剂量计水吸收剂量校准规范[S].
|
[20] |
Kawrakow I. On the effective point of measurement in megavoltage photon beams [J]. Medical Physics, 2006, 33(6):1829-1839.
|
[8] |
郭洪涛, 王小韵, 刘丰, 等. JJG 589—2008医用电子加速器辐射源检定规程[S]. 北京: 中国标准出版社, 2008.
|
[14] |
Renaud J, Sarfehnia A, Marchant K, et al. Direct measurement of electron beam quality conversion factors using water calorimetry [J]. Medical Physics, 2015, 42(11): 6357-6368.
|
[16] |
Krauss A, Kapsch R P. Direct determination of kQ factors for cylindrical and plane-parallel ionization chambers in high-energy electron beams from 6 MeV to 20 MeV [J]. Physics in Medicine and Biology, 2018, 63(3):03504.
|
[18] |
Zink K, Wulff J. Beam quality corrections for parallel-plate ion chambers in electron reference dosimetry [J]. Physics in Medicine and Biology, 2012, 57(7):1831-1854.
|
[22] |
Muir B R, McEwen M R, Rogers D W O. Beam quality conversion factors for parallel-plate ionization chambers in MV photon beams [J]. Medical Physics, 2012, 39(3):1618-1631.
|
|
Wang K, Jin S J, Wang Z P, et al. Establishment and clinical application of absorbed dose tracebility system for radiotherapy of medical accelerator [J]. China Metrology, 2019(7):77-80.
|
[5] |
IAEA. Accuracy requirements and uncertainties in radiotherapy:International Atomic Energy Agency Human Health Series Report No 31[R]. 2016.
|
[7] |
Andreo P, Burns D T, Hohlfeld K, et al. Absorbed Dose Determination in External Beam Radiotherapy: An International Code of Practice for Dosimetry Based on Standards of Absorbed Dose to Water: IAEA TRS-398[R]. 2004.
|
[13] |
Almond P R, Biggs P J, Coursey B M, et al. AAPMs TG-51 protocol for clinical reference dosimetry of high-energy photon and electron beams [J]. Medical Physics, 1999, 26(9):1847-1870.
|
[15] |
Muir B R, Cojocaru C D, McEwen M R, et al. Electron beam water calorimetry measurements to obtain beam quality conversion factors [J]. Medical Physics, 2017, 44(10):5433-5444.
|
[17] |
Muir B R, McEwen M R, Rogers D W O. Determination of relative ion chamber calibration coefficients from depth-ionization measurements in clinical electron beams [J]. Physics in Medicine and Biology, 2014, 59(19):5953-5969.
|
|
Wang K, Zhang J, Wang Z P, et al. Absolute Measurement and International Comparison of Absorbed Dose to Water for Accelerator Photon Beams by Water Calorimeter [J]. Acta Metrologica Sinica, 2020, 41(12): 1552-1558.
|
[11] |
ICRU. Recommendations of the International Commission of Radiological Units (ICRU)[J]. The British journal of radiology,1954,27:243-245.
|
[21] |
Mcewen M R, Kawrakow I, Ross C K. The effective point of measurement of ionization chambers and the build-up anomaly in MV x-ray beams [J]. Medical Physics, 2008, 35(3):950-958.
|
[19] |
Burns D T, Ding G X, Rogers D W O. R50 as a beam quality specifier for selecting stopping-power ratios and reference depths for electron dosimetry. Medical Physics [J]. 1996, 23(3):383-388.
|
|
|
|