摘要目的 探讨乳腺癌调强放射治疗中使用0°托架支撑板的可行性.方法 选择2015年10月至2017年2月保乳术后行全乳腺+瘤床同步补量调强放射治疗病例60例,采用随机数表法将病例分成3组各20例,第一组支撑板角度选择12°,第二组选择7°,第三组选择0°;比较3组患者患侧肺V20、V5、Dmean,各组左乳患者心脏V10、V30、Dmean差异及准直器角度差别,分析各组摆位误差的分布并计算群体系统误差和随机误差.结果 3组病例患侧肺V20、V5、Dmean,左乳患者心脏V10、V30、Dmean之间差异无统计学意义(P>0.05);各组准直器角度与支撑板角度的和近似为固定值13.4°.3组病例的摆位误差,只有z(前后)方向的差异有统计学意义(χ2=78.32,P<0.001),此方向0°组中位数最接近0值且四分位间距最小;绝对误差y(头脚)、z方向的差异有统计学意义(χ2=7.63、22.61,P<0.05),z方向3组数据递进减小且0°组值最小,y方向12°组最小,但与0°组差别不大.3组病例的群体系统误差x(左右)、z方向0°组最小,y方向12°组最小.结论 乳腺托架支撑板0°是可行的,倾斜角可由准直器转角代替,且可显著减小z方向的摆位误差.

abstractsObjective To explore the feasibility to set the breast board support plate angle to 0° for breast cancer patient in the intensity modulated radiation therapy. Methods A total of 60 patients with breast cancer who received the simultaneous integrated boost intensity-modulated radiation therapy ( SIB-IMRT) after breast-conserving surgery were enrolled form Oct 2015 to Feb 2017. They were randomly divided into three groups that the angle of the breast board support plate was 12°, 7° and 0° respectively. The ipsilateral lung V20 , V5 , Dmean , the heart V10 , V30 , Dmean and the collimator angle were compared among three groups. In addition, the distribution of the setup error was analyzed and the group system error and random error were calculated. Results There were no statistically significant differences in the ipsilateral lung V20, V5, Dmean and the heart V10, V30, Dmean among the three groups(P >0. 05). The sum of the collimator angle and the angle of the support plate was about 13. 4° for each group. Only the setup error of z (vertical) direction was statistically different (χ2 =78. 32, P<0. 001) and the median of the 0° group was closest to the value 0 and the quartile spacing was the smallest. The absolute error of y ( longitudinal) , z directions was statistically different (χ2 =7. 63, 22. 61,P<0. 05). In the z direction, the absolute error was reduced as the angle of the support plate decreased and 0°group was the smallest. In the y direction, the absolute error at 12° was the smallest, but had little difference with that at 0°. Among three groups, the smallest system error of the x(lateral) direction and y direction was at 0°, while that of the z direction was at 12°. Conclusions To set the breast board support plate 0° is feasible. The angle of the support plate can be replaced by the collimator angle, while the setup error of z direction could be significantly reduced.