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Year : 2014  |  Volume : 10  |  Issue : 4  |  Page : 883-888

Is volumetric modulated arc therapy (RapidArc) better than intensity modulated radiotherapy for gynecological malignancies? A dosimetric comparison

1 Department of Radiation Oncology, Rajiv Gandhi Cancer Institute and Research Centre, New Delhi - 110 085, India
2 Department of Radiation Physics, Rajiv Gandhi Cancer Institute and Research Centre, New Delhi - 110 085, India

Correspondence Address:
Manoj Kumar Sharma
Flat No. 63, Meghdoot Apartment, Sector 10 A, Gurgaon - 122 001, Haryana
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0973-1482.138208

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Aims: Evaluation of the dosimetric advantage, if any, of RapidArc (double arc and triple arc [DA and TA]) over standard fixed field intensity-modulated radiation therapy (IMRT) in gynecologic malignancies. Materials and Methods: A total of 20 cases of gynecologic malignancies were included. Static IMRT sliding window, single arc (SA), DA and TA plans were generated with eclipse planning system. The prescribed dose was 50.4 Gy/28# to the planning target volumes. Results: IMRT provided target coverage equivalent to DA and inferior to TA (D95% [in Gy] - 49.94, 49.58, 49.96, 50.17 for IMRT, SA, DA and TA respectively-all observations in the same sequence). Conformity index 90 (CI 90 (0.964, 0.927, 0.918, 0.822) and homogeneity index (0.0683, 0.119, 0.098, 0.097) of IMRT were superior. TA was superior to other arcs in all parameters except CI 90 (P = 0.805) and bladder dose (lower in DA). Rectal, bladder and bowel sparing was best achieved with IMRT followed by TA; bilateral femur dose was lower in arcs. The total monitor units and treatment time of arcs were significantly lower than IMRT, reduced by a factor of 2.41-2.59 and 3.2-3.5 respectively (All P values significant). Conclusion: IMRT provided better overall plan for gynecologic malignancies with lower organs at risk dose and target coverage equivalent to DA and TA. Treatment delivery efficiency was higher with RapidArc. The TA plan is dosimetrically superior to DA, but the gain is small. The decision whether or not to add a third arc for a small gain should be individualized.

Abstract in Chinese

在治疗妇科恶性肿瘤上,体积调整的弧治疗(RapidArc)优于调强放射治疗吗?剂量学比较 摘要 目的:评价在妇科恶性肿瘤中,快速弧治疗RapidArc(双圆弧和三弧[ DA和TA ])较标准放疗固定野调强放疗(IMRT)可能存在的剂量学优势。 材料和方法:共20例妇科恶性肿瘤患者。静态调强放射治疗的滑动窗口,单弧(SA),双弧DA和三弧TA计划由Eclipse计划系统生成。处方剂量为50.4 Gy/28 F PTV。 结果:调强放射治疗提供靶区覆盖剂量等效于DA,但不如TA。(IMRT,SA,DA和TA各自以相同顺序观察的D95% [Gy为单位] 分别为49.94,49.58,49.96,50.17)。一致性指数90(CI90(0.964,0.927,0.918,0.822),均匀性指数(0.0683,0.119,0.098,0.097),IMRT较好。TA的所有参数优于其他弧,除了CI90(P = 0.805)和膀胱剂量(DA较低)。直肠,膀胱和小肠保护最好的是IMRT,其次是TA;双侧股骨剂量较低的为弧治疗。总监控单元和治疗时间上,弧明显低于IMRT,分别减少了2.41-2.59因子和3.2-3.5因子(P值显著)。 结论:在妇科恶性肿瘤放疗中,调强放射治疗在靶区覆盖剂量相当于DA和TA的前提下,提供了更好的整体计划,表现在低危险器官剂量。治疗传输效率较高的是快速弧治疗RapidArc。TA的计划在剂量测定上优于DA,但收益小。决定是否为一个小的增益而加上第三个弧应个体化分析。 关键词:双圆弧,妇科恶性肿瘤,单圆弧,三圆弧,容积调强弧形治疗

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