锥形束CT图像引导下对乳腺癌放疗不同体位固定方式的摆位误差分析

Analysis on positioning error of different body position fixation methods guidedby cone beam CT images in breast cancer radiotherapy

目的 探讨基于锥形束CT(CBCT)图像的颈胸一体热塑膜和体部热塑膜两种体位固定方式对乳腺癌改良根治术后放疗定位的平移误差和旋转误差的差异。方法 选取2022年1月至2023年9月该院收治的82例乳腺癌改良根治术后放疗患者为研究对象,根据放疗固定方式分为颈胸膜组(使用颈胸一体热塑膜,52例)和体膜组(使用体部热塑膜,30例)。所有患者在首次放疗和放疗过程中每周进行CBCT扫描,并将验证图像与计划图像进行配准,记录两种固定方式下左右方向(X)、头脚方向(Y)和腹背方向(Z)的平移误差,以及X轴旋转方向(Rx)、Y轴旋转方向(Ry)、Z轴旋转方向(Rz)的绕轴旋转误差,比较两组摆位误差的差异。结果 首次治疗、治疗1周后和治疗2周后,两组X、Y、Z、Rx、Ry、Rx摆位误差比较,差异无统计学意义(P>0.05)。治疗3周后,与体膜组比较,颈胸膜组X[0.21(0.12,0.27)mm vs. 0.22(0.20,0.35)mm]、Y[0.20(0.11,0.24)mm vs. 0.25(0.16,0.37)mm]、Z[0.15(0.08,0.25)mm vs. 0.20(0.15,0.29)mm]、Rx[0.57(0.22,1.10)°vs. 1.00(0.70,1.50)°]、Ry[0.50(0.30,1.20)°vs. 1.10(0.60,1.40)°]、Rz[0.30(0.20,0.80)°vs. 0.90(0.40,1.50)°]的摆位误差更小(P<0.05)。治疗4周后,与体膜组比较,颈胸膜组X[0.19(0.12,0.27)mm vs. 0.25(0.21,0.31)mm]、Y[0.21(0.11,0.27)mm vs. 0.26(0.22,0.32)mm]、Z[0.12(0.05,0.28)mm vs. 0.22(0.13,0.35)mm]、Rx[0.80(0.49,1.10)°vs. 1.20(0.80,1.80)°]、Ry[0.55(0.20,1.12)°vs. 1.10(0.80,1.30)°]、Rz[0.61(0.29,1.10)°vs. 1.10(0.80,1.40)°]的摆位误差也更小(P<0.05)。结论 颈胸一体热塑膜较体部热塑膜可以减小乳腺癌放疗摆位误差。

Objective To investigate the difference of translational error and rotational error in the radiotherapeutic positioning after breast cancer modified radical surgery by using the two fixation methods of the cervicothoracic thermoplastic membrane and body thermoplastic membrane based on conical beam CT(CBCT)images.Methods A total of 82 patients with radiotherapy after breast cancer modified radical surgery admitted and treated in this hospital from January 2022 to September 2023 were selected as the study subjects and divided into the cervicothoracic membrane group(using the cervicothoracic thermoplastic membrane,n=52)and body membrane group(using the body thermoplastic membrane,n=30)according to the radiotherapeutic fixation methods.All patients weekly conducted the CGCT scanning in the first time radiotherapy and radiotherapeutic period.The verification image conducted the retification with the planned image.The translational errors in the left and right direction(X),head and foot direction(Y)and abdominal and dorsal direction(Z)were recorded,as well as the rotation errors around the axis under the two fixing methods,including the rotation error of the X-axis rotation direction(Rx),Y-axis rotation direction(Ry),and Z-axis rotation direction(Rz).The differences in positioning errors were compared between the two groups.Results There was no significant difference in X,Y,Z,Rx,Ry and Rx positioning error between the two groups after the first treatment,1-week treatment and 2-week treatment(P>0.05).After 3-week treatment,the positioning errors in X[0.21(0.12,0.27)mm vs.0.22(0.20,0.35)mm],Y[0.20(0.11,0.24)mm vs.0.25(0.16,0.37)mm],Z[0.15(0.08,0.25)mm vs.0.20(0.15,0.29)mm],Rx[0.57(0.22,1.10)°vs.1.00(0.70,1.50)°],Ry[0.50(0.30,1.20)°vs.1.10(0.60,1.40)°]and Rz[0.30(0.20,0.80)°vs.0.90(0.40,1.50)°]in the cervicothoracic membrane group were smaller compared with the body membrane group(P<0.05).After 4-week treatment,the positioning errors in X[0.19(0.12,0.27)mm vs.0.25(0.21,0.31)mm],Y[0.21(0.11,0.27)mm vs.0.26(0.22,0.32)mm],Z[0.12(0.05,0.28)mm vs.0.22(0.13,0.35)mm],Rx[0.80(0.49,1.10)°vs.1.20(0.80,1.80)°],Ry[0.55(0.20,1.12)°vs.1.10(0.80,1.30)°]and Rz[0.61(0.29,1.10)°vs.1.10(0.80,1.40)°]in the cervicothoracic membrane group were also smaller compared with the body membrane group(P<0.05).Conclusion The thecervicothoracic thermoplastic membrane could reduce the positioning error in the breast cancer radiotherapy compared with the body thermoplastic membrane.