Kamrava Mitchell, Chung Melody P, Kayode Oluwatosin, Wang Jason, Marks Leonard, Kupelian Patrick, Steinberg Michael, Park Sang-June, Demanes D Jeffrey
Department of Radiation Oncology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA; Jonsson Comprehensive Cancer Center, Los Angeles, CA.
Brachytherapy. 2013 Sep-Oct;12(5):434-41. doi: 10.1016/j.brachy.2012.09.002. Epub 2013 Feb 11.
To determine the utility of focal high-dose-rate brachytherapy for localized prostate cancer, we investigated the impact on target coverage and dose to organs at risk (OARs) with hemigland (HG) compared with whole-gland (WG) treatment.
A total of 10 WG implants were used to generate 10 WG and 20 HG (left and right) treatment plans optimized with the inverse planning simulation annealing algorithm using Oncentra MasterPlan (Nucletron B.V., Veenendaal, The Netherlands). The standard distribution of 17-18 catheters designed for WG was used to generate HG plans. The same OARs namely bladder, rectum, and urethra contours and dose constraints were applied for HG and WG plans. The HG contour was a modification of the WG contour whereby the urethra divided the prostate into HGs. The prescription dose was 7.25 Gy×6. Evaluated dose parameters were target dose D90, V100, and V150 and D0.1 cc, D1 cc, and D2 cc to OARs.
The HG plans had a D90, V100, and V150 to the HG target of 112%, 97.6%, and 33.8%, respectively. The WG plans had a D90, V100, and V150 to the WG target of 108%, 98.8%, and 26.5%, respectively. The OAR D2 cc doses were significantly lower in HG vs. WG plans: rectum (53.1% vs. 64.1%, p<0.0001), bladder (55.9% vs. 67.5%, p<0.0001), and urethra (69.3% vs. 95.2%, p<0.0001).
In the present model, HG plans yielded a statistically significant decreased radiation dose to OARs and provided complete target coverage with a catheter array designed for WG coverage. The good dosimetry results obtained in this study support the feasibility of HG brachytherapy by using a subset of the WG catheter array. Catheter distribution and dosimetry refinements tailored to subtotal prostate brachytherapy should be explored to see if further improvements in dosimetry can be achieved.
为了确定局部高剂量率近距离放射治疗对局限性前列腺癌的效用，我们研究了与全腺体（WG）治疗相比，半腺体（HG）治疗对靶区覆盖范围和危及器官（OARs）剂量的影响。
总共使用10个WG植入物来生成10个WG和20个HG（左和右）治疗计划，这些计划使用Oncentra MasterPlan（荷兰维嫩达尔的Nucletron B.V.公司）的逆向计划模拟退火算法进行优化。为WG设计的17 - 18根导管的标准分布用于生成HG计划。HG和WG计划应用相同的OARs，即膀胱、直肠和尿道轮廓以及剂量限制。HG轮廓是WG轮廓的一种修改，其中尿道将前列腺分为HG。处方剂量为7.25 Gy×6。评估的剂量参数为靶区剂量D90、V100和V150以及OARs的D0.1 cc、D1 cc和D2 cc。
HG计划对HG靶区的D90、V100和V150分别为112%、97.6%和33.8%。WG计划对WG靶区的D90、V100和V150分别为108%、98.8%和26.5%。与WG计划相比，HG计划中OAR的D2 cc剂量显著更低：直肠（53.1%对64.1%，p<0.0001）、膀胱（55.9%对67.5%，p<0.0001）和尿道（69.3%对95.2%，p<0.0001）。
在当前模型中，HG计划使OARs的辐射剂量在统计学上显著降低，并通过为WG覆盖设计的导管阵列实现了完全的靶区覆盖。本研究中获得的良好剂量学结果支持了使用WG导管阵列的一个子集进行HG近距离放射治疗的可行性。应探索针对前列腺部分近距离放射治疗量身定制的导管分布和剂量学优化，以查看是否能在剂量学上取得进一步改进。
