乳腺癌保乳术后俯卧位适形调强放射治疗摆位误差分析

Prone Position Set-up Error Analysis of Conformal Modulating Radiotherapy for Patients Accepted Breast Cancer Conserving Surgery

目的:探讨乳腺癌保乳术后俯卧位适形调强放射治疗采用BionixRT-6025胸部俯卧位系统的摆位误差。方法:20例乳腺癌保乳术后行适形调强放射治疗,采用BionixRT-6025胸部俯卧位系统固定,使用电子射野影像系统(EPID)对首次放疗、第十次放疗摄取适形调强放疗的正、侧位共80幅射野图像,与计划系统的正、侧位标准射野数字重建图像(DRR)进行比较,测得摆位误差。结果:20例患者左右方向(X)、头脚方向(Y)、前后方向(Z)在加速器下的首次放疗和第十次放疗的摆位误差X±s(mm)分别为x1(2.7±0.7)mm、y1(2.9±0.8)mm、z1(1.8±0.5)mm和x2(3.0±0.6)mm、y2(3.4±0.7)mm、z2(1.9±0.5)mm。x1较z1、y1较z1、x2较z2、y2较z2,差异均有统计学意义(P<0.05)。结论:采用BionixRT-6025胸部俯卧位系统行保乳术后患者放疗的摆位误差在放疗可接受误差范围之内,值得推广应用。

Objective： To investigate the prone position set-up errors of three-dimensional conformal modulating radiotherapy for breast cancer patients who had accepted breast conserving surgery. Methods： Twenty patients who accepted breast-conserving surgery received three-dimensional conformal modulating radiotherapy fixed by chest prone position system （BionixRT-6025 ）. A total of 80 images of the front and lateral radiation area of the intensity modulated radiotherapy were taken at the first and the 10th radiotherapy using electronic portal imaging system （EPID）. Through comparing with the front and lateral images in planning system generated by digitally reconstructed radiographs （DRR） , the prone position set-up errors were obtained. Results： For the first time and the 10th ra- diotherapy, the mean set-up errors on X, Y, Z direction were xl （ 2. 7 ± 0. 7 ） ram, yl （ 2. 9 ± 0. 8 ） mm, zl （ 1.8 ± 0. 5 ）mm and x2 （ 3.0 ± 0. 6） mm, y2 （3.4 ±0. 7） ram, z2 （ 1.9 ± 0. 5 ） ram, respectively. Comparing xl with zl, yl with zl, x2 with z2, y2 with z2, the errors were all significantly difference（ P 〈 0. 05 ）. Conclusion ： Positioning errors of the post breast-conserving surgery radiotherapy using BionixRT-6025 chest prone position system is limited in the acceptable error range and the BionixRT-6025 chest prone position system is worthy of extensive application.