Pelagade Satish, Maddirala Harshavardhan Reddy, Misra Rahul, Suryanarayan U, Neema J P
Department of Medical Physics.
Department of Medical Physics.
Med Dosim. 2015 Autumn;40(3):235-9. doi: 10.1016/j.meddos.2015.01.003. Epub 2015 Mar 17.
The aim of this study was to compare the clinical benefits of inverse planning simulated annealing (IPSA)-based optimization over volume-based optimization for high-dose rate (HDR) cervix interstitial implants. Overall, 10 patients of cervical carcinoma were considered for treatment with HDR interstitial brachytherapy. Oncentra Master Plan brachytherapy planning system was used for generating 3-dimensional HDR treatment planning for all patients. All patient treatments were planned using volume-based optimization and inverse planning optimization (IPSA). The parameters V100, V150, and V200 for the target; D(2 cm³) of bladder, rectum, and sigmoid colon; and V80 and V100 for bladder, rectum, and sigmoid colon were compared using dose-volume histograms (DVHs). The conformity index (CI), relative dose homogeneity index, overdose volume index (ODI), and dose nonuniformity index (DNR) were computed from cumulative DVHs. Good target coverage for prescription dose was achieved with volume-based optimization as compared with IPSA-based dose optimization. Homogeneity was good with the IPSA-based technique as compared with the volume-based dose optimization technique. Volume-based optimization resulted in a higher CI (with a mean value of 0.87) compared with the IPSA-based optimization (with a mean value of 0.76). ODI and DNR are better for the IPSA-based plan as compared with the volume-based plan. Mean doses to the bladder, rectum, and sigmoid colon were least with IPSA. IPSA also spared the critical organs but with considerable target conformity as compared with the volume-based plan. IPSA significantly reduces overall treatment planning time with improved reduced doses to the organs at risk compared with the volume-based optimization treatment planning method.
本研究的目的是比较基于逆向计划模拟退火（IPSA）的优化与基于体积的优化在高剂量率（HDR）宫颈间质植入治疗中的临床益处。总体而言，10例宫颈癌患者被纳入高剂量率间质近距离放射治疗。使用Oncentra Master Plan近距离放射治疗计划系统为所有患者生成三维高剂量率治疗计划。所有患者的治疗均采用基于体积的优化和逆向计划优化（IPSA）。使用剂量体积直方图（DVH）比较靶区的V100、V150和V200参数；膀胱、直肠和乙状结肠的D(2 cm³)；以及膀胱、直肠和乙状结肠的V80和V100。从累积DVH计算适形指数（CI）、相对剂量均匀性指数、过量体积指数（ODI）和剂量不均匀性指数（DNR）。与基于IPSA的剂量优化相比，基于体积的优化实现了对处方剂量的良好靶区覆盖。与基于体积的剂量优化技术相比，基于IPSA的技术具有良好的均匀性。基于体积的优化产生的CI较高（平均值为0.87），而基于IPSA的优化产生的CI较低（平均值为0.76）。与基于体积的计划相比，基于IPSA的计划的ODI和DNR更好。基于IPSA的计划中，膀胱、直肠和乙状结肠的平均剂量最低。与基于体积的计划相比，IPSA也能保护关键器官，但靶区适形性较好。与基于体积的优化治疗计划方法相比，IPSA显著减少了总体治疗计划时间，同时降低了对危及器官的剂量。
