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目的比较分析鼻咽癌固定射野调强(IMRT)和容积旋转调强(VMAT)计划的靶区和危及器官(OAR)的剂量差异及分次治疗时间和机器跳数的差异。方法选择在我院接受放疗的15例鼻咽癌患者,对其进行IMRT和VMAT计划设计的比较。结果靶区:VMAT的大部分参数的HI和CI及D1%和Dmeans优于IMRT计划的结果。OAR:虽然脑干的Dmeans、左右视神经的D1%及右晶体的D1%的差异无统计学意义,但其余指标差异均有统计学意义,且VMAT的结果优于IMRT。分次治疗时间:VMAT(4.1 min)要少于IMRT(8.8 min)。分次治疗跳数:VMAT(597.7 MUs)要比IMRT(823.5 MUs)少约37.8%。结论鼻咽癌的IMRT和VMAT计划在靶区剂量和OAR保护上都可以达到临床要求,但VMAT的大部分指标要优于IMRT。不过,VMAT在对视神经及晶体等小体积OAR的保护上没有太大优势。VMAT的分次治疗时间和机器跳数都要小于IMRT。
Objective To compare the dose differences of target and organ at risk (OAR) between NPC and IMRT and the difference between treatment time and machine hops. Methods Fifteen patients with nasopharyngeal carcinoma who underwent radiotherapy in our hospital were selected and their IMRT and VMAT plans were compared. RESULTS TARGETS: HI and CI for most of the VMAT parameters and D1% and Dmeans were superior to those for the IMRT program. OAR: Although Dmeans of the brain stem, D1% of the left and right optic nerves and D1% of the right lens were not statistically different, the differences of the other indexes were statistically significant, and the results of VMAT were superior to IMRT. Treatment times: VMAT (4.1 min) less than IMRT (8.8 min). Hyphenated treatment hops: VMAT (597.7 MUs) was about 37.8% less than IMRT (823.5 MUs). Conclusions The IMRT and VMAT plans for nasopharyngeal carcinoma can meet the clinical requirements both for target dose and OAR protection, but most of VMAT indicators outperform IMRT. However, VMAT has little benefit in protecting small volumes of OAR such as the optic nerve and crystals. VMAT fractional treatment time and machine hops should be less than IMRT.