宫颈癌容积旋转调强放疗中不同弧数目计划间的剂量学差异  

Dosimetric differences between volumetric modulated arc therapy plans with different arc numbers for cervical cancer

作　　者：龙雨松[1] 谭军文 王占宇[1] 贺先桃 梁卫学[1] LONG Yusong, TAN Junwen, WANG Zhanyu, HE Xiantao, LIANG Weixue(Radiotherapy Section of Oncology Department, the Fourth Affiliated Hospital of Guangxi Medical University, Liuzhou 545005, Guangxi Zhuang Autonomous Region, Chin)

机构地区：[1]广西医科大学第四附属医院肿瘤科放疗室,广西柳州545005

出　　处：《医疗卫生装备》2018年第6期58-62,71,共6页Chinese Medical Equipment Journal

摘　　要：目的:研究宫颈癌容积旋转调强放疗计划中弧数目对治疗计划的影响,为临床应用中容积旋转调强放疗弧数目的选取提供参考。方法:取10例宫颈癌术后患者的定位CT图像,由放疗医师勾画靶区以及危及器官,给予靶区5 040 cGy/28次的处方剂量,用RayStation计划系统针对同一患者分别设计单弧、双弧和三弧计划,比较其靶区和危及器官的剂量学特性,记录计划设计优化所需时间,分析机器跳数和治疗时间的差异,并对完成后的计划进行剂量验证,分析弧数目对通过率的影响。结果:10例宫颈癌患者的单弧、双弧和三弧计划均能满足临床要求,随着弧数目的增加,靶区分布更优,危及器官直肠、膀胱、股骨头受到40、45 Gy剂量照射的体积V_(40)、V_(45)及平均剂量D_(mean)逐渐降低,正常组织在接近处方剂量部分的35、40、45 Gy剂量照射的体积V_(35)、V_(40)、V_(45)随弧数目的增加而减少;随着弧数目的增加,计划单次优化时间和出束时间随之增加,但三者的机器跳数相差较小;3种计划的剂量验证通过率均达99.5%以上,且差异较小。结论:宫颈癌容积旋转调强放疗计划随着弧数目的增加,其靶区剂量分布以及对危及器官的保护更具优势,但是治疗时间也随之延长,相应的费用也随之增加。因此,需综合考虑选取容积旋转调强放疗计划的弧数目。Objective To study the effects of the number of arcs in the treatment of cervical cancer with volumetric modulated arc therapy （VMAT） on the treatment plan, and to provide reference for the selection of the number of arcs in the clinical application. Methods CT images of 10 patients with cervical cancer were selected, it＇s the radiation therapist that delineated the target area and organs, the prescribed dose was 5 040 cGy per 28 times to the target area, and single arc（Arc1）, double arc （Arc2） and three （Arc3） plan were designed by RayStation planning system to compare the differences with the dosimetry characteristics of target and organs. The time required for planning optimization was recorded, and the difference between the monitor unit and the delivery time in the three plans was analyzed.A dose validation tool for PTW was used to verify the dose to analyze the influence of the number of arc on the passing rate of gamma verification. Results Single arc plan （Arc1）, double arc plan （Arc2） and three arc plan （Arc3） for 10 cases of cervical cancer all proved to meet the clinical requirements. With the increase of arc number, the target area distribution got improved, V40, V45 and Dmean in the organs at risk of rectum, bladder, and femoral head gradually decreased in case of doses of 40 and 45 Gy, and V35, V40 and V45 in the normal tissue were lowered in case of the doses of 35, 40 and 45 Gy. With the increase of the arc number, the optimization time and the delivery time of the plan increased, while the difference between the monitor unit of the three plans was smaller. The passing rate of the three plans was more than 99.5%, and the difference was small. Conclusion Cervical cancer VMAT plan has the target dose distribution and the protection of organs at risk enhanced with the increase of the number of arcs, while the treatment time and cost increased. Therefore, it is necessary to take comprehensive considerations on the number of VMAT plan arcs.

关 键 词：宫颈癌 容积旋转调强放疗 弧数目 剂量学 危及器官 靶区 

分 类 号：R318[医药卫生—生物医学工程] R815.6[医药卫生—基础医学]