Prostate seed implantation using 3D-computer assisted intraoperative planning vs. a standard look-up nomogram: Improved target conformality with reduction in urethral and rectal wall dose
Prostate seed implantation using 3D-computer assisted intraoperative planning vs. a standard look-up nomogram: Improved target conformality with reduction in urethral and rectal wall dose
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DOI：
10.1016/j.ijrobp.2004.08.003
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发表时间：
2004-12-01
影响因子：
7
通讯作者：
Yang, J
中科院分区：
文献类型：
--
作者：
Raben, A;Chen, H;Yang, J
目的：为了比较两种实时前列腺粒子植入（PSI）技术之间的剂量测定结果，以评估三维（3D）术中计算机计划对目标覆盖范围，适形性，和预设尿道和直肠剂量constrains.Methods和材料的影响：114例临床局限性前列腺癌患者进行超声引导下经会阴PSI的前列腺与I-125源作为单一疗法。从1999年到2001年，69名患者使用标准查找列线图进行了实时植入（第1组：NG-PSI）。所有患者均采用改良的外周加载技术植入，其中将计算的总放射性的75-80%输送至腺体外周，剩余的20-25%放射性置于腺体内部，以达到144戈伊的处方剂量（PD），从而以可接受的均匀性覆盖腺体。未进行术前或术中计划以设定尿道或直肠前壁的剂量限制。将该组的剂量结果与2001年后使用术中3D计算机计划系统植入的45例患者（第2组：3D-PSI）进行比较。在计划系统中使用了类似的改良外周加载技术作为选项。术前对尿道（V150 < 35%）、前列腺（V100 > PD的95%; D90：140-180戈伊）和直肠壁（V110 < 1.5 cc）进行剂量限制，并在外周负荷后进行实时剂量反馈。进行手动剂量优化以确定内部针头位置以及I-125源的剩余数量和放置，以遵守尿道和直肠限制以及目标覆盖目标。两组均接受了植入后CT分析，以确定V100（前列腺）、D90（前列腺）、V150（尿道）和V110（直肠）的剂量测定结果。进行单变量和多变量分析以确定影响剂量测定结果的变量。结果：对植入前和植入后变量的分析表明，植入前腺体体积的中位数没有差异（33 cc vs. 35 cc; p = 0.31），中位mCi/种子强度（0.4 vs. 0.45 mCi; p = 0.23）、中位V100（94% vs. 94%）或植入后第30天的中位D90（165戈伊vs. 160戈伊; p = 0.26）。然而，对于第2组（3D-PSI），植入的中位总mCi（26 vs. 33 mCi; p < 0.0001）和植入的粒子的中位数量（67 vs. 83; p < 0.0001）显著减少。超过D90 > 180戈伊的患者百分比从第1组的29%降至第2组的16%（p = 0.08）。观察到接受D90 < 140戈伊的患者百分比降低（第1组14% vs第2组9%，p = 0.56）。与NG-PSI相比，第2组的V150中位数（尿道）在3D-PSI下显着降低（63%与17%; p < 0.0001）。在第1组中观察到88%的V150（尿道）> 30%，而在第2组中观察到29%，p < 0.0001。同样，第1组的中位V110（直肠）显著高于第2组（1.93 vs. 0.26 cc; p < 0.0001）。组1和组2中V110（直肠）> 1.5 cc的患者百分比分别为57%和13（p < 0.0001）。结论：采用3D计算机术中剂量计划和优化前列腺粒子植入导致尿道和直肠壁剂量显著降低，同时与使用标准查找列线图相比，在180戈伊以上和140戈伊以下具有降低的剂量变化性的情况下，始终产生优异的靶覆盖。此外，总mCi和实现改善的适形性所需的种子数量的减少是显著的，并且可能对成本节约有影响。(C)2004年爱思唯尔公司
Purpose: To compare dosimetric outcomes between two real-time prostate seed implantation (PSI) techniques to evaluate the impact of three-dimensional (3D) intraoperative computer planning on target coverage, conformality, and preset urethral and rectal dose constraints.Methods and Materials: One hundred and fourteen patients with clinically localized prostate cancer underwent ultrasound-guided transperineal PSI of the prostate with I-125 sources as monotherapy. From 1999 to 2001, 69 patients were implanted in real-time using a standard look-up nomogram (Group 1: NG-PSI). All patients were implanted with a modified peripheral loading technique in which 75-80% of the calculated total activity was delivered to the gland periphery, with the remaining 20-25% activity placed in the gland interior, to achieve a prescribed dose (PD) of 144 Gy to cover the gland with acceptable homogeneity. No preoperative or intraoperative planning was performed to set dose constraints to the urethra or anterior rectal wall. Dosimetric outcome from this group was compared with 45 patients subsequently implanted after 2001 using an intraoperative 3D computer planning system (Group 2: 3D-PSI). A similar modified peripheral loading technique was used as an option in the planning system. Preoperative dose constraints were placed on the urethra (V150 < 35%), prostate (V100 > 95% of PD; D90: 140-180 Gy), and rectal wall (V110 < 1.5 cc) with real-time dosimetric feedback performed after peripheral loading. Manual dose optimization was performed to determine interior needle position and remaining number and placement of I-125 sources to adhere to urethral and rectal constraints and target coverage goals. Both groups underwent postimplant CT analysis to determine dosimetric outcome with regard to V100(prostate), D90(prostate), V150(urethra), and V110(rectum). Univariate and multivariate analysis was performed to determine variables impacting on dosimetric outcome.Results: Analysis of preimplant and postimplant variables demonstrated no difference in the median preimplant gland volume (33 cc vs. 35 cc; p = 0.31), median mCi/seed strengths (0.4 vs. 0.45 mCi; p = 0.23), median V100 (94% vs. 94%), or median D90 at postimplant Day 30 (165 Gy vs. 160 Gy; p = 0.26) between Groups 1 and 2. However, for Group 2 (3D-PSI) the median total mCi implanted (26 vs. 33 mCi; p < 0.0001) and the median number of seeds implanted (67 vs. 83; p < 0.0001) were reduced substantially. The percent of patients exceeding a D90 > 180 Gy was reduced from 29% in Group 1 to 16% in Group 2 (p = 0.08). A reduction was observed in the percent of patients receiving a D90 < 140 Gy (14% Group 1 vs. 9% Group 2, p = 0.56). The median V150(urethra) for Group 2 was reduced dramatically with 3D-PSI compared with NG-PSI (63% vs. 17%; p < 0.0001). A V150(urethra) > 30% was observed in 88% in Group 1 compared with 29% in Group 2, p < 0.0001. Similarly, the median V110(rectum) for Group 1 was significantly higher than that in Group 2 (1.93 vs. 0.26 cc; p < 0.0001). The percent of patients with V110(rectum) > 1.5 cc in Group 1 and Group 2 was 57% and 13%, respectively (p < 0.0001).Conclusions: The adoption of 3D computer intraoperative dose planning and optimization for prostate seed implantation resulted in dramatic reductions in urethral and rectal wall doses, while consistently producing excellent target coverage with reduced dose variability above 180 Gy and below 140 Gy, compared with the use of a standard look-up nomogram. Additionally, the reduction in total mCi and number of seeds needed to achieve improved conformality was substantial and may have implications for cost savings. (C) 2004 Elsevier Inc.