Deng Xia, Han Ce, Chen Shan, Xie Congying, Yi Jinling, Zhou Yongqiang, Zheng Xiaomin, Deng Zhenxiang, Jin Xiance
Radiotherapy and Chemotherapy Department, the 1st Affiliated Hospital of Wenhzou Medical University, Wenzhou, China.
Department of Clinical Solutions Support, Elekta Instrument (Shanghai) Ltd., Shanghai, China.
J Appl Clin Med Phys. 2017 Jan;18(1):25-31. doi: 10.1002/acm2.12003. Epub 2016 Nov 21.
As the advantage of using complex volumetric-modulated arc therapy (VMAT) in the treatment of gynecologic cancer has not yet been fully determined, the purpose of this study was to investigate the dosimetric advantages of VMAT by comparing directly with whole pelvic conformal radiotherapy (CRT) and intensity-modulated radiotherapy (IMRT) in the treatment of 15 postoperative cervical cancer patients. Four-field CRT, seven-field IMRT, and two-arc VMAT plans were generated for each patient with identical objective functions to achieve clinically acceptable dose distribution. Target coverage and OAR sparing differences were investigated through dose-volume histogram (DVH) analysis. Nondosimtric differences between IMRT and VMAT were also compared. Target coverage presented by V95% were 88.9% ± 3.8%, 99.9% ± 0.07%, and 99.9% ± 0.1% for CRT, IMRT, and VMAT, respectively. Significant differences on conformal index (CI) and conformal number (CN) were observed with CIs of 0.37 ± 0.07, 0.55 ± 0.04, 0.61 ± 0.04, and CNs of 0.33 ± 0.06, 0.55 ± 0.04, 0.60 ± 0.04 for CRT, IMRT, and VMAT, respectively. IMRT and VMAT decreased the dose to bladder and rectum significantly compared with CRT. No significant differences on the Dmean, V45, and V30 of small bowel were observed among CRT, IMRT, and VMAT. However, VMAT (10.4 ± 4.8 vs. 19.8 ± 11.0, P = 0.004) and IMRT (12.3 ± 5.0 vs. 19.8 ± 11.0, P = 0.02) decreased V40, increased the Dmax of small bowel and the irradiation dose to femoral heads compared with CRT. VMAT irradiated less dose to bladder, rectum, small bowel and larger volume of health tissue with a lower dose (V5 and V10) compared with IMRT, although the differences were not statistical significant. In conclusion, VMAT and IMRT showed significant dosimetric advantages both on target coverage and OAR sparing compared with CRT in the treatment of postoperative cervical cancer. However, no significant difference between IMRT and VMAT was observed except for slightly better dose conformity, slightly less MU, and significant shorter delivery time achieved for VMAT.
由于在妇科癌症治疗中使用复杂容积调强弧形放疗（VMAT）的优势尚未完全确定，本研究的目的是通过将15例宫颈癌术后患者的VMAT与全盆腔适形放疗（CRT）和调强放疗（IMRT）直接比较，来研究VMAT的剂量学优势。为每位患者生成具有相同目标函数的四野CRT、七野IMRT和双弧VMAT计划，以实现临床上可接受的剂量分布。通过剂量体积直方图（DVH）分析研究靶区覆盖和危及器官（OAR）保护差异。还比较了IMRT和VMAT之间的非剂量学差异。CRT、IMRT和VMAT的V95%所呈现的靶区覆盖分别为88.9%±3.8%、99.9%±0.07%和99.9%±0.1%。观察到适形指数（CI）和适形数（CN）有显著差异，CRT、IMRT和VMAT的CI分别为0.37±0.07、0.55±0.04、0.61±0.04，CN分别为0.33±0.06、0.55±0.04、0.60±0.04。与CRT相比，IMRT和VMAT显著降低了膀胱和直肠的剂量。在CRT、IMRT和VMAT之间，小肠的平均剂量（Dmean）、V45和V30未观察到显著差异。然而，与CRT相比，VMAT（10.4±4.8 vs. 19.8±11.0，P = 0.004）和IMRT（12.3±5.0 vs. 19.8±11.0，P = 0.02）降低了V40，增加了小肠的最大剂量（Dmax）和股骨头的照射剂量。与IMRT相比，VMAT对膀胱、直肠、小肠的照射剂量更低，对健康组织的低剂量（V5和V10）照射体积更大，尽管差异无统计学意义。总之，在宫颈癌术后治疗中，与CRT相比，VMAT和IMRT在靶区覆盖和OAR保护方面均显示出显著的剂量学优势。然而，除了VMAT的剂量适形性稍好、机器跳数（MU）稍少以及治疗时间显著缩短外，未观察到IMRT和VMAT之间有显著差异。
