乳腺托架加发泡胶提升乳腺癌放疗体位固定精度的研究

Breast bracket combined with polyurethane foam improves the accuracy of immobilization in breast cancer radiotherapy

目的比较乳腺托架联合发泡胶固定和单发泡胶固定在乳腺癌放疗体位固定精度上的差异,为临床选择更优固定方式提供参考。方法选取2021年3月至2021年7月在中山大学肿瘤防治中心进行放疗的乳腺癌患者50例,其中25例患者使用发泡胶固定(发泡胶组),另外25例患者使用发泡胶联合乳腺托架固定(联合组)。所有患者予每周1次CBCT扫描,获得左右(LR)、头脚(SI)、腹背(AP)方向误差并进行t检验,应用公式M_(PTV)=2.5Σ+0.7σ分别计算出对应的PTV外扩边界。结果发泡胶组LR、SI、AP方向的摆位误差分别是(0.88±2.76)、(2.0±3.26)、(1.22±3.55)mm,俯仰(Rtn)、翻滚(Pitch)、旋转(Roll)角度误差分别为-0.24°±0.85°、0.16°±1.11°、-0.32°±1.05°,对应的外扩边界分别是6.75、8.46、8.73 mm;联合组LR、SI、AP方向的摆位误差分别是(0.62±2.74)、(1.0±3.01)、(1.82±3.21)mm,Rtn、Pitch、Roll角度上的误差分别为0.64°±0.59°、0.71°±1.22°、0.29°±0.73°,对应的外扩边界分别是6.35、7.47、7.61 mm。两组的误差比较,LR、SI、AP方向和Rtn、Pitch、Roll角度的t值分别为-4.304、-2.681、1.384、-9.457、-3.683、-5.323,其中在LR、SI、Rtn、Pitch以及Roll方向上差异具有统计学意义(P<0.05)。结论使用发泡胶联合乳腺托架固定方式比单纯使用发泡胶固定效果更好,计划外扩边界也更小,因此推荐临床上乳腺癌放疗使用发泡胶联合乳腺托架固定技术。

Objective To compare the difference between breast bracket combined with polyurethane foam and single polyurethane foam in the accuracy of immobilization,providing a better immobilization for breast cancer radiotherapy.Methods Fifty breast cancer patients who received radiotherapy in Sun Yat-sen University Cancer Center from March 2021 to July 2021 were selected.Among them,25 patients were immobilized with polyurethane foam(foam group),and the other 25 patients were immobilized with polyurethane foam combined with breast bracket(combination group).All patients were scanned by CBCT once a week to obtain setup errors in the SI,LR and AP directions for t-test.The formula M_(PTV)=2.5Σ+0.7σwas used to calculate the margin of the planning target volume(M_(PTV)).Results The setup errors in the foam group were SI(2.0±3.26)mm,LR(0.88±2.76)mm,AP(1.22±3.55)mm,Rtn-0.24°±0.85°,Pitch 0.16°±1.11°,Roll-0.32°±1.05°,and the M_(PTV) were 6.75 mm,8.46 mm and 8.73 mm,respectively.The setup errors in the combination group were SI(1.0±3.01)mm,LR(0.62±2.74)mm,AP(1.82±3.21)mm,Rtn 0.64°±0.59°,Pitch 0.71°±1.22°,Roll 0.29°±0.73°,and the M_(PTV) were 6.35 mm,7.47 mm,and 7.61 mm,respectively.After comparing the setup errors in the three-dimensional directions between two groups,the t value of LR,SI,AP and Rtn,Pitch,Roll was-4.304,-2.681,1.384,and-9.457,-3.683,-5.323,respectively.And the differences in the LR,SI,Rtn,Pitch and Roll directions were statistically significant(all P<0.05).Conclusions The immobilization effect of polyurethane foam combined with breast bracket is better and the M_(PTV) is also smaller than those of polyurethane foam alone.Therefore,it is recommended to use polyurethane foam combined with breast bracket for immobilization in breast cancer radiotherapy.