Analysis of positioning error of vacuum pad and breast bracket in base note radiotherapy for breast conserving surgery for breast cancer based on cone beam CT
Objective To analyze the positioning error of vacuum pad and breast bracket in base note radiotherapy for breast cancer with breast conserving surgery based on cone beam CT(CBCT).Methods A total of 120 patients who received IMRT after breast conserving surgery for breast cancer in the radiotherapy department of Nantong Cancer Hospital from April 2020 to April 2022 were retrospectively selected.According to the fixation method,the patients were divided into two groups:group A(n=60)was fixed with a vacuum pad,and group B(n=60)was fixed with a breast bracket.CBCT was used to evaluate the placement,and the placement errors and the occurrence of radiation dermatitis in each group were analyzed.Results The translation errors of group A and group B in the left and right directions were(0.33±0.12)cm and(0.34±0.15)cm,respectively,and there was no statistically significant difference between the groups(P＞0.05).The errors in the direction of the abdomen and back were 0.32(0.11,0.42)cm and 0.15(0.09,0.21)cm,respectively,while the errors in the direction of the head and foot were 0.34(0.16,0.34)cm and 0.23(0.15,0.37)cm,respectively.The translation errors of the head,foot,and abdomen and back in group B were smaller than those in group A(all P＜0.05).Patients in group B had significantly smaller translation errors in the left and right directions[group A:(0.31±0.13)cm,group B:(0.18±0.05)cm,P＜0.05],and after rotation in the ventral and dorsal directions[group A:(0.31±0.11)cm,group B:(0.23±0.08)cm,P＜0.05].There was no statistically significant difference in translation errors after rotation in the head and foot directions(P＞0.05).The rotation error in the left and right directions of group B was smaller than that of group A[A:(0.98 0.12)°,group B:(0.67±0.31)°,P＜0.05].There was no statistically significant difference in the comparison of head foot and abdominal back rotation errors(all P＞0.05).The planned center point(MIDM)of group B patients was located 10 cm to the left and right horizontally(MIDL,MIDR),with MIDM moving 8 cm to the head side(SM),MIDL moving 8 cm to the head side(SL),MIDR moving 8 cm to the head side(SR),MIDM moving 8 cm to the foot side(IM),MIDL moving 8 cm to the foot side(IL),and MIDR moving 8 cm to the foot side(IR).The thickness of the phantom was lower than that of group A(all P＜0.05).At the completion of treatment,the total incidence of high-grade radiation dermatitis in group A was 61.67％(37/60),while the total incidence of high-grade radiation dermatitis in group B was 41.67％(25/60).The incidence of high-grade radiation dermatitis in group B was lower than that in group A(P＜0.05).Conclusions Using breast bracket for breast fixation after breast conserving surgery for breast cancer can reduce the positioning error,the phantom thickness and the incidence of high-grade radiation dermatitis during intensity modulated radiotherapy,which is of high clinical value.
维普
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