Breast cancer radiotherapy positioning quality control based on optical surface monitoring system
Objective To explore the feasibility and effectiveness of optical surface monitoring system(OSMS)in quality control of radiotherapy for breast cancer.Methods From September 2017 to March 2020,a total of 60 female patients with breast cancer were enrolled,which aged 27-71 years old with mean age of 46.1 years old(standard deviation 9.91 years old).The surgical treatment was radiotherapy after breast conserving surgery in 26 cases and radiotherapy after total mastectomy in 34 cases.There were 43 cases of tumor located in left breast and 17 cases in right breast.According to OSMS quality control,all of them were divided into experimental group(n=29,added OSMS quality control during positioning process)and control group(n=31,without OSMS quality control during positioning process).In experimental group,the OSMS repeatability mon-itoring was added after positioning,the translation error and rotation error of repeatability positioning were measured by OSMS,and fixation device was adjusted according to measurement results.Without the OSMS assistance,the control group was routinely positioned according to department positioning process.In subsequent radiotherapy,the set-up images were collected and position deviation data of 2 groups were recorded,and set-up deviation of 2 groups was analyzed.Results The set-up deviation of experimental group was generally small,there were significant differences in Z(abdominal-dorsal direc-tion)and total deviation[(0.056±0.286)cm vs(0.192±0.406)cm,(0.474±0.237)cm vs(0.661±0.299)cm.P＜0.01].The systematic error and random error of experimental group were small,the differences in X(left-right direction)and Z were statistically significant(P＜0.05),the calculated planning target volume(PTV)margin was smaller than that of control group.In experimental group,distribution range of positioning error in X,Y and Z was more concentrated in small error(≤0.3 cm),and the difference was statistically significant(P＜0.01).Conclusion It is demonstrated that radiotherapy positioning of breast cancer based on OSMS is safe and effective,which can identify the treatment position and marker points with poor repeatability,and help to improve quality of radiotherapy positioning.
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