关键词: 宫颈癌, 容积旋转调强, 准直器, 放射治疗

Abstract: Objective To explore the application effect of personalized volumetric modulated arc therapy collimator angle optimization in cervical cancer radiotherapy. Methods Ten patients with cervical cancer were selected and VMATapt and VMAT20 plans were designed. The VMATapt was randomly divided into three section arcs. According to the projection of the PTV at different gantry angles and based on the minimum field sizes，the optimal segmentation mode and the optimal collimator angle for each section of the arc were calculated in the VMATapt plan. The VMAT20 was planned for a conventional design with a collimator angle of 20°. Compared the averaged Jaw size，the dosimetric parameters of the target area and endangered organs，the machine units（MUs），and the average dose of 2 cm outside the target area（PTV+2 cm） between the two plans. Results Compared with the VMAT20 plan，the averaged Jaw size of VMATapt plan was smaller［（20.2±0.9） cm² vs （18.5±0.7） cm²，P<0.001］，homogeneity index was better［（0.06±0.01） vs （0.05±0.02），P=0.001］，MUs and PTV^{+2 cm} were lower（P<0.05）. However，there were no significant differences in PTV parameters，organ parameters，and conformal index value between the two plans（P>0.05）. Conclusion VMATapt plan can meet the prescription dose requirements of patients with cervical cancer by using the personalized volumetric modulated arc therapy collimator angle optimization method，and improve the target uniformity and reduce the machine units and PTV_{+2 cm} outside the target area compared to the VMAT20 plan，which can be used for cervical cancer VMAT design.

Key words: Cervical cancer, Volumetric modulated arc therapy, Collimator angle, Radiotherapy