控制点与弧数目对宫颈癌放疗计划剂量学的影响  

Effects of control points and number of arcs on dosimetry of cervical cancer radiotherapy planning

作　　者：冯永富 谭军文 贺先桃 李钢 梁卫学[1] 韦婷[1] 龙雨松[1] FENG Yong-fu;TAN Jun-wen;HE Xian-tao;LI Gang;LIANG Wei-xue;WEI Ting;LONG Yu-song(Room of Radiotherapy,Department of Oncology, the Fourth Affiliated Hospital of Guangxi Medical University,Liuzhou 545005,Guangxi Zhuang Autonomous Region,China)

机构地区：[1]广西医科大学第四附属医院肿瘤科放疗室

出　　处：《医疗卫生装备》2019年第7期39-43,48,共6页Chinese Medical Equipment Journal

基　　金：广西卫计委自筹经费科研课题(Z20180502)

摘　　要：目的:研究不同弧数目及控制点间距对宫颈癌放疗计划剂量学的影响,为容积旋转调强放射治疗(volumetric modulated arc therapy,VMAT)计划弧数目及控制点的选择提供参考。方法:选取广西医科大学第四附属医院接受放疗的10例宫颈癌患者,分别设计控制点间距为2、3和4°时的单、双弧VMAT计划,通过比较研究,分析放疗计划在不同弧数目及控制点间距时的剂量变化。结果:双弧计划靶区近似最大剂量D2%(覆盖2%计划靶区的最小吸收剂量,以此类推)和中位剂量D50%均比单弧计划小,近似最小剂量D98%略高于单弧计划;控制点间距越小,靶区D2%和D50%越小。双弧计划靶区均匀性、适形度优于单弧计划,且控制点间距越小,靶区均匀性及单弧计划适形度越好。大多数危及器官V45(接受45 Gy剂量照射的体积,以此类推)、V50和平均剂量Dmean随控制点和弧数目的增加而降低,但对弧数目的影响更大。1 mm/1%、2 mm/2%和3 mm/3%通过标准下,各控制点间距下的γ通过率有少许波动,双弧计划γ通过率比单弧计划稍高,但均无统计学意义。结论:控制点及弧数目的增加可适度降低危及器官受照剂量,提升靶区均匀性及适形度,相较于控制点的增加,弧数目的增加对剂量影响更具优势。γ通过率随弧数目的增加稍有提高,控制点的变化对其影响不大。Objective To study the effects of different arc numbers and control point spacing on the dosimetry of cervical cancer radiotherapy planning, and to provide references for the selection of arc numbers and control points of volumetric modulated arc therapy(VMAT) planning. Methods A total of ten patients with cervical cancer were selected who received radiotherapy in the Fourth Affiliated Hospital of Guangxi Medical University. Each case was designed with single arc and two arc VMAT plans in 2, 3 and 4 degrees spacing of control points respectively. The dose changes of radiotherapy planning were analyzed in different number of arcs and control point spacing through comparative study. Results The planning target volume near-maximum absorbed dose(D2%, minimum absorbed dose that covered 2% of the volume of the planning target volume(PTV) and so on) and median absorbed dose(D50%) of two-arc planning were lower than the single-arc planning, while the near-minimum absorbed dose(D98%) was slightly higher. The smaller control point spacing, the lower PTV D2% and D50%.Target region homogeneity and conformity of two-arc planning were better than that of single-arc planning, and the smaller spacing between control points, the better homogeneity of target area and the conformity of single-arc planning. The V45(volumes exposed to 45 Gy and so on), V50 and mean absorbed dose(Dmean) of most organs at risk(OAR) decreased with the increase of control points and the number of arcs, while the impact of arc was greater. The gamma passing rate varied insignificantly between each control point spacing under the standard of 1 mm/1%, 2 mm/2% and 3 mm/3%, and the passing rate of two arc plan was slightly higher than that of single arc plan, while the differences were not statistically. Conclusion The increase of control points and number of arcs can reduce the dose of radiation to the OAR, and improve the homogeneity and conformity of the target area. The increase of arc number has more advantages on the effect of dose compared with the inc

关 键 词：宫颈癌 控制点 弧数目 剂量学 容积旋转调强放射治疗 

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