乳腺癌改良根治术后放疗体位固定技术探讨

目的 探讨2种不同体位固定技术对乳腺癌患者改良根治术后放疗重复摆位精度的影响.方法 50例乳腺癌改良根治术后需行辅助放疗的患者按随机数字法分为翼形板+真空垫组(25例)和头颈肩热塑体膜组(25例)采取相应固定体位.在治疗过程中每例通过锥形束CT(cone beam computer tomography,CBCT)测量5次摆位误差,共获取250组CT数据,利用X线容积成像(X-ray volume image,XVI)软件将CBCT扫描图像与计划CT图像进行自动骨性配准,比较两组三维平移方向(X轴、Y轴、Z轴)和旋转方向(ROLL、PITCH、YAW)的摆位误差值.结果 翼形板+真空垫组射野中心点在X轴(左右)、Y轴(头足)和Z轴(前后)方向上摆位误差分别为(2.20±1.65)mm、(2.95±2.10) mm和(2.37±2.14) mm;在ROLL、PITCH和YAW方向上摆位误差值分别为(1.25±0.96)°、(0.45 ±0.53)°和(0.61±0.52)°.头颈肩热塑体膜组射野中心点在X轴(左右)、Y轴(头足)和Z轴(前后)方向上摆位误差分别为(2.29±1.89)mm、(2.49±1.79)mm和(1.67±0.95) mm;在ROLL、PITCH和YAW方向上摆位误差值分别为(0.81±0.92)°、(0.43±0.51)°和(0.53±0.64)°.两组在Z轴及ROLL方向的摆位误差比较差异均具有统计学意义(均P＜0.05).结论 乳腺癌改良根治术后患者放疗时采用热塑头颈肩体膜固定技术可以改善摆位的重复性,有助于体位的固定,减少摆位误差,提高患者治疗定摆位的精度.

Immobilization techniques in radiotherapy of breast cancer after modified radical mastectomy

Objective To compare the influence of two different position fixation techniques on the setup error of radiotherapy towards breast cancer patients after modified radical mastectomy.Methods Fifty breast cancer patients,who had taken modified radical mastectomy and were receiving adjuvant radiotherapy,were included in the study.Patients were randomly divided into two groups:25 cases in the wing plate and vacuum cushion fixed position group,and 25 cases in the head and neck shoulder thermoplastic membrane fixed position group.In the course of treatment,5 setup errors were measured by cone beam CT (CBCT) for each patient and 250 sets of CT data were obtained.CBCT scan images and planning CT images were automatically bone marked by X-ray volume image (XVI) software,and the setup error values in the threedimensional translation direction (X,Y,Z) and rotational direction (ROLL,PITCH,YAW) were compared.Results For the wing plate and vacuum cushion fixed position group,the setup errors in the center of the X-axis (left-right),Y-axis (cranial-caudal) and Z-axis (anterior-posterior) directions were (2.20 ± 1.65) mm,(2.95 ± 2.10) mm and (2.37 ± 2.14)mm,respectively.The set up errors in ROLL,PITCH and YAW directions were(1.25 ± 0.96)°,(0.45 ± 0.53) ° and(0.61 ± 0.52) °,respectively.For the head and neck shoulder thermoplastic membrane fixed position group,the setup error in the center of the X-axis (left-right),Y-axis (cranial-caudal) and Z-axis (anterior-posterior) directions were (2.29±1.89)mm,(2.49±l.79)mm and (1.67 + 0.95)mm,respectively.The set up errors in ROLL,PITCH and YAW directions were (0.81 ± 0.92) °,(0.43 ± 0.51) ° and (0.53 ± 0.64) °,respectively.Statistically significant differences were found for the setup errors of the two groups in both the Z-axis and ROLL direction (P ＜ 0.05).Conclusion For breast cancer patients after modified radical mastectomy,position fixation with head and neck shoulder thermoplastic membrane can improve the setup repeatability,reduce the setup error,and enhance the setup accuracy during radiotherapy.