宫颈癌VMAT计划中OAR的DVH预测价值

Predictive value of dose-volume histograms of organs at risk in volumetric modulated arc therapy plans for cervical cancer

目的：探讨宫颈癌 VMAT放疗计划中膀胱、直肠和小肠等 OAR的 DVH预测价值。方法选取100例宫颈癌VMAT计划为学习组，分析该组患者解剖信息与膀胱、直肠和小肠V30、V40和V50指数的相关性。采用SVR算法建立解剖信息与OAR的DVH间对应关系。利用解剖信息对验证组20例VMAT计划的OAR的DVH进行预测。结果膀胱、直肠和小肠的DVH可能主要受其与靶区空间位置关系影响。 SVR 算法对验证组中膀胱V30、V40、V50预测误差分别为（－2．4±3.5）％、（－2．5±3.8）％、（－1．5±4.9）％，对直肠的预测误差分别为（0．5±2.6）％、（－1．5±5.1）％、（－2．0±7.4）％，对小肠的预测误差分别为（－2．9±5.3）％、（2．7±7.7）％、（5．3±11.1）％。结论对先验宫颈癌VMAT计划中解剖信息与OAR的DVH的相关性学习后，SVR算法可利用解剖信息准确地预测出膀胱、直肠和小肠的DVH。

Objective To investigate the predictive value of dose-volume histograms （ DVHs ） of organs at risk （ OARs ） including the bladder, rectum, and small intestine in volumetric modulated arc therapy （ VMAT） plans for cervical cancer. Methods A total of 100 VMAT plans for cervical cancer were assigned into the learning group. The correlation of the anatomical information with the V30 , V40 , and V50 values of the bladder, rectum, and small intestine was evaluated in the group. The support vector regression （ SVR） algorithm was used to establish the correspondence between the anatomical information and the DVHs of OARs. The DVHs of OARs in the verification group containing 20 VMAT plans were predicted based on the anatomical information. Results The DVHs of the bladder, rectum, and small intestine were likely to be influenced mainly by the spatial relationship between these OARs and target volume. In the verification group, the prediction errors of V30,V40 and V50 by SVR algorithm were-2.4%±3. 5%,-2.5%±3. 8%, and-1.5%±4. 9% for the bladder, 0.5%±2. 6%,-1.5%±5. 1%, and-2.0%±7. 4% for the rectum, and-2.9%± 5. 3%, 2.7%±7. 7%, and 5.3%±11. 1% for the small intestine, respectively. Conclusions After learning the correlation between the anatomical information and the DVHs of OARs from prior VMAT plans for cervical cancer, SVR algorithm can precisely predict the DVHs of the bladder, rectum, and small intestine based on the anatomical information.