Method of measuring the activity of 192Ir radioactive source for afterloading brachytherapy using well-type ionization chamber and quality assurance of the activity of radioactive source(PDF)
《中国医学物理学杂志》[ISSN:1005-202X/CN:44-1351/R]
- Issue:
- 2021年第4期
- Page:
- 416-421
- Research Field:
- 医学放射物理
- Publishing date:
Info
- Title:
- Method of measuring the activity of 192Ir radioactive source for afterloading brachytherapy using well-type ionization chamber and quality assurance of the activity of radioactive source
- Author(s):
- LUO Bin1; 2; LI Xianfu1; 2; GUO Fei2; CAO Lu2; XU Peng2; XIE Li2; YANG Huadong2
- 1. Sichuan Key Laboratory of Medical Imaging, Key Disciplines of Oncology in Sichuan Province, Nanchong 637000, China 2. Department of Oncology, Affiliated Hospital of North Sichuan Medical College, Nanchong 637000, China
- Keywords:
- Keywords: well-type ionization chamber 192Ir radioactive source activity verification
- PACS:
- R312；R811.1
- DOI:
- DOI:10.3969/j.issn.1005-202X.2021.04.004
- Abstract:
- Abstract: Objective To describe the theoretical basis and specific method of measuring the activity of radioactive source for afterloading brachytherapy using well-type ionization chamber, and to conduct a verification for the activity of 192Ir radioactive source. Methods The conversion coefficient between ionization chamber current and 192Ir source activity was firstly calculated by the calibration factor of well-type ionization chamber system, and then a plan was made to find the effective residence point for the measurement of 192Ir source activity. The current generated by 192Ir source on the effective residence point irradiated on the ionization chamber was measured by PTW Unidos E dosimeter and PTW SOURCECHECK 4 π well-type ionization chamber, and the obtained current was converted into source activity. After 7 months of continuous measurement, paired sample t-test was conducted on the measured data and the calculated data for analyzing the differences between two groups of data. Results The relative deviations between the measured data and the calculated data of newly-purchased 192Ir source in Affiliated Hospital of North Sichuan Medical College were all within ±1% in 14 measurements, with a maximum deviation of 0.946%, which met the requirements of the source activity stability test (within ±5%) of WS 262-2017 specification for testing of quality control in gamma-ray sources afterloading brachytherapy and reached the standard of 192Ir source activity calibration (within±3%) of AAPM clinical application. Moreover, the results of paired sample t-test showed that there was no significant difference between the measured data and the calculated data (P=0.665>0.05). Conclusion Well-type ionization chamber can be used to accurately measure 192Ir source activity. The radioactive source used in Affiliated Hospital of North Sichuan Medical College decays according to the ideal half-life, with less impurities and high purity.
Last Update: 2021-04-29