RESUMO
Objective To evaluate the application of improved belly board in postoperative patients of rectal cancer radiotherapy and explore the influence of its set-up repeatability.Methods CBCT was used to measure the intra fractional and inter fractional setup errors using normal or improved belly board respectively.The data was analyzed with statistic method.Results There was no significance of intra fractional setup errors on x-axis (P ＞ 0.05).There was significance on y and z-axis (P ＜ 0.05).There was no significance of interfrational setup errors on x-axis (P ＞ 0.05) and there was significance on y and z-axis (P ＜ 0.05) using normal belly board.There was no significance of intrafractional setup errors on x,y and z-axis (P ＞ 0.05).There was also no significance of interfractional setup errors on x,y and z-axis (P ＞ 0.05) with using improved belly board.Conclusion The method of improved belly board has more advantage than nomal belly board in controlling set-up repeatability,and it is conductive to improve accuracy of patients treatment.