Measurement of beam quality correction factor based on absorbed dose to water in high-energy photon beams(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2017年第12期
- Page:
- 1196-1199
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Measurement of beam quality correction factor based on absorbed dose to water in high-energy photon beams
- Author(s):
- CHANG Xue; WANG Kun; ZHANG Jian; JIN Sunjun; WANG Zhipeng
- National Institute of Metrology, Beijing 100027, China
- Keywords:
- ; high-energy photon beam; absorbed dose to water; international comparison; beam quality correction factor
- PACS:
- R312
- DOI:
- DOI:10.3969/j.issn.1005-202X.2017.12.002
- Abstract:
- Abstract: Objective To briefly introduce the results of the international comparison of absorbed dose to water at National Institute of Metrology (NIM), and based on the results, to provide the beam quality correction factors for 9 common types of cylindrical ionization chambers. Methods In the [60Co γ] primary standard dosimetry laboratory at NIM, the calibration factors of 9 types of cylindrical ionization chambers at the reference quality [60Co γ] were measured. In the high-energy photon beams primary standard dosimetry laboratory at NIM, the calibration factors of the corresponding cylindrical ionization chambers at the reference quality 6, 10 MV photon were also measured. Based on the obtained calibration factors, we calculated the beam quality correction factors of cylindrical ionization chambers which were then compared with the data given in IAEA TRS-398 protocol. Results The primary standard dosimetry laboratory of absorbed dose to water at NIM had the ability for the transmission and traceability of absorbed dose to water. Based on this result, the experiment values of the beam quality correction factors for tested cylindrical ionization chambers had a good agreement with the values given in IAEA TRS-398 protocol, with a relative deviation less than 0.9%. Generally, the measured beam quality correction factors were slightly smaller than the values in IAEA TRS-398 protocol, because the calibration factors in [60Co γ] primary standard dosimetry laboratory at NIM are larger than the values given by International Atomic Energy Agency (IAEA) and the calibration factors in high-energy photon beams primary standard dosimetry laboratory at NIM are smaller than the values given by the International Bureau of Weights and Measures. Conclusion The primary standard dosimetry laboratory of absorbed dose to water at NIM could accurately measure the beam quality correction factors of users’ cylindrical ionization chambers.
Last Update: 2017-12-20