基于螺旋断层治疗的全身皮肤照射体位固定新技术初步观察

Preliminary observation of new immobilization for total skin irradiation with helical tomotherapy

目的初步观察不同体位固定技术在螺旋断层治疗技术下进行全身皮肤照射(TSI)的可行性。方法对中山大学肿瘤防治中心接受TSI治疗的3例蕈样霉菌病患者分别采用低温热塑高分子材料俯卧位固定、潜水衣结合负压真空袋仰卧位固定、低温热塑高分子材料结合真空袋仰卧位固定方法,观察固定效果并计算平均摆位误差、靶区适形指数(CI)、靶区均匀性指数(HI)和靶区Dmean。结果3种体位固定方式均起到良好固定效果,设计的放疗计划各参数均能达到临床要求。3例患者平均摆位误差在左右、头脚、腹背方向分别为(0.26±3.40)、(-2.63±4.63)、(6.13±4.86)mm,靶区CI为0.56±0.09、HI为1.186±0.059、Dmean为(2586.56±63.28)cGy。结论低温热塑高分子材料或潜水衣都可以联合真空袋进行TSI治疗的体位固定。通过补偿膜剂量建成效应提高表皮剂量达临床要求,为螺旋断层治疗技术进行TSI提供了安全可靠的体位固定方法。

Objective To preliminarily observe the feasibility of different immobilization techniques for total skin irradiation(TSI)using helical tomotherapy.Methods Three eczema scrophuloderma patients treated with TSI in Sun Yat-sen University Cancer Center were immobilized with low-temperature thermoplastic in a prone position,diving suit combined with negative pressure vacuum bag in a supine position,low-temperature thermoplastic combined with vacuum bag in a supine position,respectively.Different immobilization effects were observed.The conformity index(CI)of the target area,heterogeneity index(HI)of the target area,and the mean dose(Dmean)of the target area were calculated.Results Three immobilization methods could achieve satisfactory immobilization effects,and all the dosimetric parameters of radiation treatment plans met the clinical requirements.The average set-up errors in the left and right,head and foot,and abdomen and back directions of three patients were(0.26±3.40)mm,(-2.63±4.63)mm and(6.13±4.86)mm,respectively.The CI,HI andDmean were0.56±0.09,1.186±0.059 and(2586.56±63.28)cGy.Conclusions Low-temperature thermoplastic or diving suits can be combined with vacuum bags for immobilization in TSI.The epidermal dose can be increased with bolus through the dose-building effect,which can provide a safe and reliable method for TSI in helical tomotherapy.