Morganti A G, Valentini V, Mantello G, Mattiucci G C, Luzi S, Leone M, Cellini N
Department of Radiotherapy, Universita' Cattolica del Sacro Cuore, Rome, Italy.
Int J Radiat Oncol Biol Phys. 1998 Aug 1;42(1):65-71. doi: 10.1016/s0360-3016(98)00205-3.
It was hypothesized that using a simplified technique of volumes profiles determination (STVPD) based on CT data sets (correlate and projection) would increase the target dose without increasing the bladder and rectal dose obtained by conventional simulation techniques. To test this hypothesis, patients referred for radical radiation treatment for prostate carcinoma were prospectively evaluated by performing treatment planning using standard simulation, with (SSB) and without corner blocks (SSWB), STVPD, and 3D beam's eye view.
Twenty-one patients with prostate carcinoma (stage B: 7; stage C: 14) underwent four treatment planning procedures where the field arrangement was defined by standard simulation (SSB and SSWB), STVPD, and 3D beam's eye view (BEV) with a four field (10 MV photons) box technique. Dose-volume histograms (DVHs) for the planning target volume (PTV), bladder, and rectum (relatives to the four techniques) were generated for all patients and compared; average percentage dose to the bladder and rectum were also calculated.
STVPD and 3D BEV treated an increased percentage of PTV at 95% isodose level, in comparison to standard simulation (with and without blocks). No statistically significant differences were found between the two techniques. A significant reduction of irradiated bladder volume was found between 3D BEV and STVPD versus simulation with and without blocks (mean percentage dose: 77.3%, 81.8%, 93.5%, and 92.6% respectively). No marked differences were recorded in rectal irradiation (mean percentage dose: 53.1%, 53.7%, 51.9%, and 50.2% respectively). Time required for treatment planning (excluding CT scan and definitive simulation) was less than 15 minutes for STVPD and more than 120 minutes for 3D BEV.
Our results confirm the inadequacy of standard simulation. It is possible, with conformal therapy, to increase the dose to the PTV, decreasing the irradiated volume of the bladder. The absence of sparing effect in the rectum is discussed. Using a box technique, STVPD can be used routinely to define the PTV in patients with prostate cancer, reducing the time required for treatment planning, with dosimetric results similar to those of 3D BEV.
据推测，基于CT数据集（关联和投影）使用一种简化的体积轮廓确定技术（STVPD），在不增加传统模拟技术所获得的膀胱和直肠剂量的情况下，会增加靶区剂量。为验证这一假设，对因前列腺癌前来接受根治性放射治疗的患者进行前瞻性评估，分别采用标准模拟（有角挡铅，SSB；无角挡铅，SSWB）、STVPD和三维射野方向观（3D BEV）进行治疗计划制定。
21例前列腺癌患者（B期：7例；C期：14例）接受了四种治疗计划制定程序，射野布置分别通过标准模拟（SSB和SSWB）、STVPD以及采用四野（10MV光子）盒式技术的三维射野方向观（BEV）来定义。为所有患者生成计划靶区（PTV）、膀胱和直肠（相对于四种技术）的剂量体积直方图（DVH）并进行比较；还计算了膀胱和直肠的平均百分比剂量。
与标准模拟（有挡铅和无挡铅）相比，STVPD和3D BEV在95%等剂量水平下治疗的PTV百分比增加。两种技术之间未发现统计学显著差异。与有挡铅和无挡铅的模拟相比，3D BEV和STVPD照射的膀胱体积显著减少（平均百分比剂量分别为：77.3%、81.8%、93.5%和92.6%）。直肠照射方面未记录到明显差异（平均百分比剂量分别为：53.1%、53.7%、51.9%和50.2%）。治疗计划制定所需时间（不包括CT扫描和最终模拟），STVPD少于15分钟，3D BEV超过120分钟。
我们的结果证实了标准模拟的不足。采用适形治疗，有可能增加PTV的剂量，减少膀胱的受照体积。讨论了直肠中不存在剂量 sparing效应的情况。采用盒式技术，STVPD可常规用于确定前列腺癌患者的PTV，减少治疗计划制定所需时间，剂量学结果与3D BEV相似。
