塑形垫结合热塑膜在头颈部肿瘤螺旋断层放疗体位固定中的应用研究

Application of individual head-rest combined with thermoplastic fixation mask in position fixation for irradiation with helical tomotherapy for head and neck tumors

目的比较头颈部肿瘤患者使用塑形垫结合热塑膜固定与单纯使用热塑膜固定方式的摆位误差。方法选取中国科学院大学附属肿瘤医院(浙江省肿瘤医院)2019年10月至2020年4月行螺旋断层放疗的患者28例,采用随机数字表法分为两组,使用塑形垫结合热塑膜固定的患者14例(N1组),单纯使用热塑膜固定的患者14例(N2组)。利用兆伏级螺旋CT(MVCT)扫描配准获得每个患者治疗前左右(X)、头足(Y)、腹背(Z)方向的平移和横断面(ROLL)旋转的摆位误差,N1和N2组分别扫描425、416次,共计841次,比较数据误差。结果N1组在X、Y、Z和ROLL四个方向上的摆位误差分别为(1.37±1.04)mm、(1.38±1.12)mm、(1.47±1.62)mm、(1.47±1.62)°,N2组分别为(1.57±1.21)mm、(2.10±1.51)mm、(1.61±1.50)mm、(1.40±1.30)°,N1与N2组在Y方向上的摆位误差差异有统计学意义(P=0.013)。N1组在X、Y、Z方向的外扩边界分别为4.15 mm、4.23 mm和4.81 mm,N2组外扩边界分别为4.77 mm、6.31 mm和5.08 mm。在X方向,N1和N2组以3 mm为分界点计数差异有统计学意义(χ^(2)=10.516,P<0.001)。在Y方向,以1 mm、2 mm和3 mm为分界点计数差异均有统计学意义(χ^(2)=24.889,P<0.001;χ^(2)=42.202,P<0.001;χ^(2)=46.204,P<0.001),在Z方向以2 mm为分界点计数差异有统计学意义(χ^(2)=7.335,P=0.007)。N1组在X、Y、Z方向小于3 mm的摆位误差计数分别为92%、90%、92%。结论塑形垫结合热塑膜与单纯使用热塑膜固定技术相比,能有效改善头颈部肿瘤患者摆位稳定性,减小摆位误差,有一定的创新性。

Objective To compare the positioning errors of individual head-rest combined with thermoplastic fixation mask versus thermoplastic fixation mask alone in patients with head and neck tumors.Methods Twenty-eight patients who received irradiation with helical tomotherapy in Cancer Hospital of the University of Chinese Academy of Sciences(Zhejiang Cancer Hospital)between October 2019 and April 2020 were included in this study.They were randomly assigned to receive position fixation with either individual head-rest combined with thermoplastic fixation mask(N1 group,n=14)or thermoplastic fixation mask alone(N2 group,n=14).Megavoltage computed tomography(MVCT)scanning registration was used to obtain the positioning errors in translation and rotation(ROLL)in the left-right(X),head-food(Y),and belly-back(Z)directions.There were a total of 841 CT scans,consisting of 425 scans in group N1 and 416 scans in group N2.Results The positioning errors in X,Y,Z and ROLL directions in the N1 group were(1.37±1.04)mm,(1.38±1.12)mm,(1.47±1.62)mm and(1.47±1.62)°respectively,and they were(1.57±1.21)mm,(2.10±1.51)mm,(1.61±1.50)mm and(1.40±1.30)°respectively in the N2 group.There was significant difference in positioning errors in the Y direction between N1 and N2 groups(P=0.013).In the N1 group,the outward expansion boundaries in X,Y and Z directions was 4.15 mm,4.23 mm and 4.81 mm respectively,and it was 4.77,6.31 and 5.08 mm,respectively in the N2 group.In the X direction,there was significant difference in positioning errors taking 3 mm as the dividing point between N1 and N2 groups(χ^(2)=10.516,P<0.001).In the Y direction,there was significant difference in positioning errors taking 1,2 and 3 mm as the dividing points between N1 and N2 groups(χ^(2)=24.889,P<0.001;χ^(2)=42.202,P<0.001;χ^(2)=46.204,P<0.001).In the Z direction,there was significant difference in positioning errors taking 2 mm as the dividing point between N1 and N2 groups(χ^(2)=7.335,P=0.007).In the N1 group,the percentage of positioning errors<3 mm in the X,Y and Z directions was 92%,90%and 92%,respectively.Conclusion Compared with thermoplastic fixation mask alone,individual head-rest combined with thermoplastic fixation mask can better effectively improve the positioning stability and reduce positioning errors in patients receiving irradiation with helical tomotherapy for head and neck tumors.The combined method is of certain innovation.