摘要
【目的】探讨容积旋转调强(VMAT)相比常规静态调强(s-IMRT)在鼻咽癌治疗中的剂量学特点及治疗效率。【方法】选取52名病理确诊且接受容积旋转调强放疗的初治鼻咽癌患者纳入本研究。所有患者均统一采用同步加量技术给予肿瘤靶区处方剂量70 Gy/33次,亚临床病灶区60 Gy/33次,预防照射区56 Gy/33次。每例患者采用相同剂量学限制条件分别进行容积旋转调强及常规调强计划设计(Monaco计划系统)。通过其剂量学对比分析评估:①靶区覆盖,均匀性及适形性;②危及器官剂量分布;③治疗时间及治疗跳数。【结果】两组计划均有较好靶区剂量覆盖,但PTV70常规调强组相比容积旋转的均匀性(VMAT vs.s-IMRT,1.09±0.02 vs.1.07±0.02;P<0.001)和适形性(VMAT vs.s-IMRT,0.48±0.15 vs.0.54±0.13;P<0.001)更优;同时VMAT组在正常组织上也未显示剂量学优势,VMAT组脑干剂量较s-IMRT组剂量略低(VMATvs.s-IMRT,57.99±6.43 vs.58.22±5.78;P<0.001),但脊髓,腮腺及喉的剂量较s-IMRT组高(P<0.05)。VMAT单次治疗时间(7.0 min)较IMRT(13 min)显著缩短,但平均治疗跳数(VMAT vs.s-IMRT,644±172 vs.654±180;P>0.05)无明显统计学差异。【结论】在鼻咽癌调强放疗中,容积旋转调强放射治疗可达到常规静态调强较相似的剂量分布,但治疗时间显著缩短。
[Objective] To compare volume modulated arc therapy （VMAT）with step-and-shoot intensity-modulated radiation therapy （IMRT） for nasopharyngeal carcinoma （NPC） patients with regard to the sparing effect on dosimetric quality and efficiency of delivery. [ Methods ] Fifty-two patients who were diagnosed with NPC and were treated with VMAT as their primary treatment, and had no distant metastasis were included in this study. The target area received three dose levels （70, 60, and 56 Gy） in 33 fractions using simultaneous integrated boosts technique. For a fair comparison, The Elekta Monaco Planning System was adopted to design both VMAT and IMRT plans. Dosimetric comparisons between VMAT and IMRT plans were analyzed to evaluate （1） coverage, homogeneity, and conformity of PTV, （2） sparing of OARs, （3） delivery time, and （4） monitor units （MUs）. [Results] The VMAT and IMRT plans had similar PTV coverage. IMRT plans provided a better conformity index （CI）（VMAT vs. s-IMRT, 1.09 ＋ 0.02 vs. 1.07 ± 0.02; P 〈 0.001）and homogeneity index （HI） （VMAT vs. s-IMRT, 0.48 ± 0.15 vs. 0.54 ± 0.13 ;P 〈 0.001 ） than VMAT. When compared with IMRT, VMAT a had a better sparing effect on brain stem （VMAT vs. s-IMRT,57.99 ± 6.43 vs. 58.22± 5.78; P 〈 0.001 ）, and worse on spinal cord, parotid and larynx（P 〈 0.05）. But the effect of other sparing was similar between VMAT and IMRT.The delivery time per fraction for VMAT （7.0 min） was much lower than for IMRT （13 min, P 〈 0.01）. [Conclusions] Our results indicate that VMAT provides similar dose coverage of PTVs and sparing of normal tissue to IMRT , and shorter delivery time than IMRT.
出处
《中山大学学报（医学科学版）》
CAS
CSCD
北大核心
2012年第6期835-840,855,共7页
Journal of Sun Yat-Sen University:Medical Sciences
基金
国家自然科学基金(81071836)
卫生部部属(管)医院临床学科重点项目(2010-178)
广东省高等院校珠江学者(2010)
广东省高等学校科技创新重点项目(cxzd1005)
关键词
鼻咽癌
容积旋转调强
常规静态调强
剂量学
治疗效率
nasopharyngeal carcinoma
volumetric modulated arc therapy
intensity-modulated radiation therapy
dosimetrics
e^ciency of delivery
