摘要
目的比较TrueBeam直线加速器6MVX射线均整模式（FF）和非均整模式（FFF）下容积旋转调强放疗（VMAT）在直肠癌术前放疗中的剂量学差异。方法选取15例直肠癌术前患者，在Eclipse10．0计划系统上分别进行FF．VMAT和FFF—VMAT计划设计。计划靶体积（PTV）处方剂量为50Gy／25次，2Gy／次。在95％的PTV达到处方剂量前提下，比较两种计划的剂量体积直方图（DVH）、靶区和危及器官剂量、适形度指数（CI）、均匀性指数（HI）、正常组织低剂量体积（B—P）、机器跳数及治疗时间。结果FF—VMAT计划PTv的平均剂量（Dmean）、接受105％处方剂量的体积（V105）、HI低于FFF—VMAT计划，且CI覆盖得更好（P〈0．05）。FF—VMAT计划的小肠（D5）、膀胱（D5、Dmean、V40、V50）、左侧股骨头（V40）、右侧股骨头（Dmean）低于FFF—VMAT计划（P〈0．05），B—P的V，高于FFF—VMAT计划（P〈0．05）。FF—VMAT计划的机器跳数（382±53）较FFF—VMAT计划（483±26）减少了21％（P〈0．05）；FF—VMAT计划的治疗时间[（148±4）S]与FFF—VMAT计划[（146±3）S]相似，差异无统计学意义（P〉0．05）。结论两种计划均能满足临床治疗需求，FF—VMAT计划较FFF—VMAT计划提供了更好的靶区剂量分布，且对危及器官的保护有一定优势，FFF模式下高剂量率的优势并没有得到发挥。
Objective To compare the dosimetric differences of volumetric modulated arc therapy （VMAT） for preoperative radiotherapy of rectal cancer using 6MV X-ray flattening filter-free （FFF） and flattening filter （FF） modes. Methods FF-VMAT and FFF-VMAT plans were designed for 15 rectal cancer patients with preoperative radiotherapy by planning treatment system （Eclipse 10.0）, respectively. Prescription dose of PTV was 50 Gy in 25 fractions. When the plans were normalized to 50 Gy to 95 % of PTV, the dose volume histogram （DVH）, target and risk organ doses, conformity indexes （CI）, homogeneity indexes （HI）, low dose volume of normal tissue （B-P）, monitor units （MU） and treatment time （TT） were compared between the two kinds of plans. Results FF-VMAT provided the lower Dmean V105, HI （P 〈 0.05）, and higher CI （P 〈 0.05） compared with FFF-VMAT. Small intestine （D5）, Bladder （D4, Dmean, V40, V50）, L-femoral head （V4o）, R-femoral head （Dmean） were lower in FF-VMAT than those in FFF-VMAT （P 〈 0.05）. FF-VMAT had higher B-P （V5） compared with FFF-VMAT （P 〈 0.05）. FF-VMAT reduced the monitor units （MU） by 21% （382±53 vs 483± 26, P 〈 0.05）, as well as the treatment time （TI＇） in FF-VMAT was no significant difference compared with that in FFF-VMAT [ （148±4） s vs （146±3） s, P 〉 0.05）]. Conclusions The qualities of FF-VMAT and FFF-VMAT plans were comparable and both clinically acceptable. When comparing two plans, FF-VMAT showed better target coverage and some of OARs sparing. The MUs of FFF-VMAT were higher than those of FF-VMAT, yet were not delivered within the same time.
出处
《肿瘤研究与临床》
CAS
2015年第11期732-735,共4页
Cancer Research and Clinic
基金
广东省医学科研基金（A2014455）
关键词
直肠肿瘤
术前放疗
容积旋转调强
剂量学
非均整模式
Rectal neoplasms
Preoperative radiotherapy
Volumetric modulated arc therapy
Dosimetry
Flattening filter-free
