Jacob Dayee, Raben Adam, Sarkar Abhirup, Grimm Jimm, Simpson Larry
Department of Radiation Oncology, Helen F. Graham Cancer Center, Christiana Care Health System, Newark, DE, USA.
Int J Radiat Oncol Biol Phys. 2008 Nov 1;72(3):820-7. doi: 10.1016/j.ijrobp.2008.02.009. Epub 2008 May 1.
To perform an independent validation of an anatomy-based inverse planning simulated annealing (IPSA) algorithm in obtaining superior target coverage and reducing the dose to the organs at risk.
In a recent prostate high-dose-rate brachytherapy protocol study by the Radiation Therapy Oncology Group (0321), our institution treated 20 patients between June 1, 2005 and November 30, 2006. These patients had received a high-dose-rate boost dose of 19 Gy to the prostate, in addition to an external beam radiotherapy dose of 45 Gy with intensity-modulated radiotherapy. Three-dimensional dosimetry was obtained for the following optimization schemes in the Plato Brachytherapy Planning System, version 14.3.2, using the same dose constraints for all the patients treated during this period: anatomy-based IPSA optimization, geometric optimization, and dose point optimization. Dose-volume histograms were generated for the planning target volume and organs at risk for each optimization method, from which the volume receiving at least 75% of the dose (V(75%)) for the rectum and bladder, volume receiving at least 125% of the dose (V(125%)) for the urethra, and total volume receiving the reference dose (V(100%)) and volume receiving 150% of the dose (V(150%)) for the planning target volume were determined. The dose homogeneity index and conformal index for the planning target volume for each optimization technique were compared.
Despite suboptimal needle position in some implants, the IPSA algorithm was able to comply with the tight Radiation Therapy Oncology Group dose constraints for 90% of the patients in this study. In contrast, the compliance was only 30% for dose point optimization and only 5% for geometric optimization.
Anatomy-based IPSA optimization proved to be the superior technique and also the fastest for reducing the dose to the organs at risk without compromising the target coverage.
对基于解剖结构的逆向计划模拟退火(IPSA)算法进行独立验证,以获得更好的靶区覆盖并降低危及器官的剂量。
在放射治疗肿瘤学组(0321)近期的一项前列腺高剂量率近距离放射治疗方案研究中,我们机构在2005年6月1日至2006年11月30日期间治疗了20例患者。这些患者除接受了45 Gy调强放疗外照射剂量外,还接受了19 Gy的前列腺高剂量率增敏剂量。在Plato近距离放射治疗计划系统14.3.2版本中,针对以下优化方案进行三维剂量测定,对该期间治疗的所有患者使用相同的剂量约束:基于解剖结构的IPSA优化、几何优化和剂量点优化。为每种优化方法生成计划靶区体积和危及器官的剂量体积直方图,从中确定直肠和膀胱接受至少75%剂量的体积(V(75%))、尿道接受至少125%剂量的体积(V(125%))、计划靶区体积接受参考剂量的总体积(V(100%))以及接受150%剂量的体积(V(150%))。比较了每种优化技术的计划靶区体积的剂量均匀性指数和适形指数。
尽管在一些植入物中针位欠佳,但IPSA算法能够使本研究中90%的患者符合放射治疗肿瘤学组严格的剂量约束。相比之下,剂量点优化的符合率仅为30%,几何优化的符合率仅为5%。
基于解剖结构的IPSA优化被证明是一种更优的技术,并能在不影响靶区覆盖的情况下最快地降低危及器官的剂量。