General condition of patients, and data on set-up errors and repeatability after grouping

All the enrolled patients signed the informed consent form and passed the approval of the hospital ethics committee (ethics approval number: Tongzhong Ethic 2021-089). The enrolled patients were randomly divided into three groups: hand support combined with modified head neck shoulder plate fixation group (experimental group), negative pressure vacuum pad fixation group (control group I), and breast bracket fixation group (control group II), with 36 cases in each group.

There was no statistically significant difference in general clinical data among the three groups of patients (P>0.05). The positioning error data of radiotherapy for the 4th to 6th sessions (4th to 6th) were collected from the enrolled patients, totaling 324 sessions. Calculate the mean (actual positioning error) and coefficient of variation (CV) of positioning errors for each patient from the 4th to the 6th, analyze the positioning errors of different positioning fixation techniques, and compare the CV values to analyze the repeatability of different positioning fixation techniques.