Zelefsky M J, Yamada Y, Cohen G, Venkatraman E S, Fung A Y, Furhang E, Silvern D, Zaider M
Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.
Int J Radiat Oncol Biol Phys. 2000 Sep 1;48(2):601-8. doi: 10.1016/s0360-3016(00)00655-6.
To compare the target coverage and dose to normal tissues after I-125 transperineal permanent implantation (TPI) of the prostate in 90 patients treated with one of three different transperineal techniques.
Detailed postimplant dosimetric evaluations of permanent I-125 implantation procedures were performed on 30 consecutive patients treated between 1995-1996 who underwent TPI using a preplanning CT-based technique, on 30 consecutive patients treated in 1997-1998 who underwent an ultrasound-guided approach with intraoperative determination of seed distribution based on an I-125 nomogram, and on 30 consecutive patients in 1998-1999 who underwent TPI with intraoperative computer-based 3-dimensional conformal optimization. For all three techniques, postimplant CT scans were obtained 4-6 hours after TPI. Dosimetric parameters included V(100), V(90), V(150), D(100), D(90), D(80), as well as maximal and average doses to the urethra and rectal wall. These parameter outcomes are reported as a percentage of the prescription dose.
The intraoperative 3D-optimized technique (I-3D) provided superior target coverage with the prescription dose for all dosimetric variables evaluated compared to the other treatment techniques. The median V(100), V(90), and D(90) values for the I-3D technique were 96%, 98%, and 116%, respectively. In contrast, the V(100), V(90), and D(90) values for the CT preplan and ultrasound manual optimization approaches were 86%, 89%, and 88%, respectively and 88%, 92%, and 94%, respectively (I-3D versus other techniques: p < 0.001). The superior target coverage with the I-3D technique was also associated with a higher cumulative implant activity required by the optimization program. A multivariate analysis determined that the treatment technique (I-3D versus other approaches) was an independent predictor of improved target coverage for each parameter analyzed (p < 0.001). In addition, higher cumulative implant activities and smaller prostate target volumes were independent predictors of improved target coverage. The maximum and average urethral doses were significantly lower with the I-3D technique compared to the other techniques; a modest increase in the average rectal dose was also observed with this approach.
Three-dimensional intraoperative computer optimized TPI consistently provided superior target coverage with the prescription dose and significantly lower urethral doses compared to two other techniques used. These data provide proof-of-principle that improved therapeutic ratios can be achieved with the integration of more sophisticated intraoperative planning for TPI and may potentially have a profound impact on the outcome of patients treated with this modality.
比较90例接受三种不同经会阴技术之一治疗的患者在前列腺碘-125经会阴永久植入（TPI）后靶区覆盖情况及正常组织剂量。
对1995 - 1996年连续治疗的30例采用基于CT预规划技术进行TPI的患者、1997 - 1998年连续治疗的30例采用超声引导并根据碘-125剂量图术中确定粒子分布的患者以及1998 - 1999年连续治疗的30例采用术中基于计算机的三维适形优化进行TPI的患者，进行永久性碘-125植入术后详细的剂量学评估。对于所有三种技术，在TPI后4 - 6小时进行植入后CT扫描。剂量学参数包括V(100)、V(90)、V(150)、D(100)、D(90)、D(80)，以及尿道和直肠壁的最大剂量和平均剂量。这些参数结果以处方剂量的百分比报告。
与其他治疗技术相比，术中三维优化技术（I - 3D）在所有评估的剂量学变量方面，对处方剂量的靶区覆盖情况更佳。I - 3D技术的V(100)、V(90)和D(90)的中位数分别为96%、98%和116%。相比之下，CT预规划和超声手动优化方法的V(100)、V(90)和D(90)值分别为86%、89%和88%以及88%、92%和94%（I - 3D与其他技术相比：p < 0.001）。I - 3D技术更好的靶区覆盖也与优化程序所需的更高累积植入活度相关。多因素分析确定，治疗技术（I - 3D与其他方法相比）是每个分析参数靶区覆盖改善的独立预测因素（p < 0.001）。此外，更高的累积植入活度和更小的前列腺靶体积是靶区覆盖改善的独立预测因素。与其他技术相比，I - 3D技术的尿道最大剂量和平均剂量显著更低；采用该方法还观察到直肠平均剂量有适度增加。
与另外两种使用的技术相比，术中三维计算机优化TPI始终能提供更好的处方剂量靶区覆盖，且尿道剂量显著更低。这些数据提供了原理证明，即通过整合更复杂的术中TPI规划可实现更高的治疗比，并且可能对采用这种方式治疗的患者的治疗结果产生深远影响。
