基于光学表面监视系统的乳腺癌放射治疗定位质控

Breast cancer radiotherapy positioning quality control based on optical surface monitoring system

目的将光学表面监视系统(OSMS)用于乳腺癌的放射治疗(简称放疗)定位环节的质量控制,探索其可行性和有效性。方法选择海南省肿瘤医院2017年9月至2020年3月女性乳腺癌患者60例,年龄27~71岁,平均年龄46.1岁(标准差9.91岁);手术治疗方式,保乳术后放疗26例,乳腺全切术后放疗34例;肿瘤部位,左乳43例,右乳17例。根据是否行OSMS质控,分为试验组29例(定位过程中加入OSMS质控)和对照组31例(未加入OSMS质控)。试验组定位完成后,增加OSMS重复性监测环节,通过OSMS测量患者重复摆位的平移误差和旋转误差,并依据测量结果对固定装置进行调整;对照组不加入OSMS辅助,按照科室定位流程,常规定位。在后续的放射治疗过程中,采集摆位影像,记录两组患者的位置偏差数据。分析两组的摆位偏差。结果试验组摆位偏差总体偏小。在Z方式(腹背方向)及总偏差上差异有显著统计学意义[(0.056±0.286)cm vs(0.192±0.406)cm、(0.474±0.237)cm vs(0.661±0.299)cm。P<0.01]。试验组系统误差和随机误差均偏小,在X方向(左右方向)和Z方向上差异有统计学意义(P<0.05),且计算得到的计划靶区(PTV)外放边界也更小。试验组摆位误差在X、Y、Z方向上分布区间更加集中在小误差(≤0.3 cm)范围,差异有显著统计学意义(P<0.01)。结论基于OSMS的乳腺癌放疗定位安全有效,可以识别出重复性差的治疗体位和标记点,帮助提高放疗定位质量。

Objective To explore the feasibility and effectiveness of optical surface monitoring system(OSMS) in quality control of radiotherapy for breast cancer. Methods From September 2017 to March 2020, a total of 60 female patients with breast cancer were enrolled, which aged 27-71 years old with mean age of 46.1 years old(standard deviation 9.91 years old). The surgical treatment was radiotherapy after breast conserving surgery in 26 cases and radiotherapy after total mastectomy in 34cases. There were 43 cases of tumor located in left breast and 17 cases in right breast. According to OSMS quality control,all of them were divided into experimental group(n = 29, added OSMS quality control during positioning process) and control group(n = 31, without OSMS quality control during positioning process). In experimental group, the OSMS repeatability monitoring was added after positioning, the translation error and rotation error of repeatability positioning were measured by OSMS, and fixation device was adjusted according to measurement results. Without the OSMS assistance, the control group was routinely positioned according to department positioning process. In subsequent radiotherapy, the set-up images were collected and position deviation data of 2 groups were recorded, and set-up deviation of 2 groups was analyzed. Results The set-up deviation of experimental group was generally small, there were significant differences in Z(abdominal-dorsal direction) and total deviation[(0.056 ± 0.286) cm vs(0.192 ± 0.406) cm,(0.474 ± 0.237) cm vs(0.661 ± 0.299) cm. P < 0.01].The systematic error and random error of experimental group were small, the differences in X(left-right direction) and Z were statistically significant(P < 0.05), the calculated planning target volume(PTV) margin was smaller than that of control group.In experimental group, distribution range of positioning error in X, Y and Z was more concentrated in small error(≤ 0.3 cm), and the difference was statistically significant( P < 0.01). Conclusion It is demonstrated that radiotherapy positioning of breast cancer based on OSMS is safe and effective, which can identify the treatment position and marker points with poor repeatability,and help to improve quality of radiotherapy positioning.