Abstract

Info

Title:: Statistical process control method in evaluating the stability of daily output dose of linear accelerator

Author(s):: LIU Lidong1; LI Junfeng1; LI Shuzhou2; ZHONG Meizuo1; QIN Qin1; ZHENG Le1; TANG Du2; ZHANG Xiaoming1; 1. Department of Oncology, Xiangya Changde Hospital, Changde 415000, China 2. Department of Oncology, Xiangya Hospital, Central South University, Changsha 410008, China

Keywords:: Keywords: linear accelerator statistical process control method quality control output dose stability

Abstract:: Abstract: Objective To study the stability of the 6 MV X-ray output dose of linear accelerator using statistical process control (SPC) method. Methods PTW QUICKCHECK webline was used to collect the 6 MV X-ray central-axis dose of the Varian Trilogy accelerator in Xiangya Changde Hospital within 257 working days during January to December 2019. SPC method was used to draw the mean-range control chart ([X]-R chart). The distribution of 129 sample points was obtained with the sample size of 2, and the process capability indexes (Cp and CPK) to determine the stability of output dose of the accelerator were calculated. Results Three out of 129 sample points exceeded the upper control line (points 119, 121 and 122), which remaindered the physicists to adjust the output dose during these periods. The calculated Cp=1.48 and CPK=1.35 indicated that the 6 MV X-ray central-axis dose of the accelerator was stable and was at a controllable level during the measurement. Conclusion SPC method can be used to monitor and evaluate the stability of daily output dose of linear accelerator, thereby providing critical information for quality management and ensuring the safe and stable operation of linear accelerator.