Abstract

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Title:: Application of statistical process control method in verification of air-kerma strength of 192Ir brachytherapy source

Author(s):: LUO Bin1; 2; LI Xianfu1; 2; CAO Lu2; YANG Huadong2; XU Peng2; GUO Fei2; XIE Li2; 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: statistical process control method brachytherapy 192Ir air-kerma strength process capability index

Abstract:: Abstract: Objective To analyze the accuracy and stability of statistical process control (SPC) method in the verification of the air-kerma strength (Sk) of 192Ir brachytherapy source. Methods After completing the quality control verification of 192Ir radioactive source Sk with PTW SOURCECHECK 4π well-type ionization chamber according to the requirements of national standard WS 262-2017, Minitab software was used to draw the mean value-range chart for the deviation between the measured value and the calculated value of the planning system. The corresponding upper and lower control lines and process capability indexes (Cp, Cpk) were calculated for evaluating and the accuracy and stability of SPC method. Results The distribution of the deviation values in the 25 groups ranged from -1.584% to 0.915%, reaching the limit requirements of less than ±5% in WS 262-2017 and less than ±3% in AAPM-TG43. The mean values of each group were within the range of upper and lower control lines (from -1.518% to 0.973%). Cp and Cpk were 1.66 and 1.51, respectively. The whole measurement process was at a relatively stable control level. Conclusion SPC method can better monitor and evaluate the quality control verification results (deviation values) of 192Ir brachytherapy source Sk, and find out the abnormal points, thereby ensuring the accuracy of dose delivery in brachytherapy.