Banerjee Robyn, Park Sang-June, Anderson Erik, Demanes D Jeffrey, Wang Jason, Kamrava Mitchell
Department of Oncology, University of Calgary, Calgary, Alberta T2N 4N2, Canada.
Department of Radiation Oncology, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA.
Brachytherapy. 2015 May-Jun;14(3):366-72. doi: 10.1016/j.brachy.2014.12.007. Epub 2015 Feb 10.
To assess the magnitude of dosimetric reductions of a focal and ultra-focal high-dose-rate (HDR) prostate brachytherapy treatment strategy relative to standard whole gland (WG) treatment.
HDR brachytherapy plans for five patients treated with WG HDR monotherapy were optimized to assess different treatment strategies. Plans were generated to treat the hemigland (HG), one-third gland (1/3G), and one-sixth gland (1/6G), as well as to assess treating the WG with a boost to one of those sub-volumes (WG + HG, WG + 1/3G, WG + 1/6G). Dosimetric parameters analyzed included Target D90%, V100%, V150%, Bladder (B), Rectal (R), Urethral (U) D0.1, 1 and 2cc, Urethral V75%, and the V50% to the contralateral HG. Two-tailed t tests were used for comparison of means, and p-values less than 0.05 were considered statistically significant.
Target objectives (D90 > 100% and V100 > 97%) were met in all cases. Significant organs at risk dose reductions were achieved for all approaches compared with WG plans. 1/6G vs WG plans resulted in the greatest reduction in dose with a mean bladder D2cc 24.7 vs 64.8%, rectal D2cc 32.8 vs 65.3%, urethral D1cc 52.1 vs 103.8%, and V75 14.5 vs 75% (p < 0.05 for all comparisons).
Significant dose reductions to organs at risk can be achieved using HDR focal brachytherapy. The magnitude of the reductions achievable with treating progressively smaller sub-volumes suggests the potential to reduce morbidity, but the clinical impact on morbidity and tumor control remain to be investigated.
评估聚焦和超聚焦高剂量率（HDR）前列腺近距离放射治疗策略相对于标准全腺（WG）治疗的剂量学降低幅度。
对5例接受WG HDR单一疗法治疗的患者的HDR近距离放射治疗计划进行优化，以评估不同的治疗策略。生成了治疗半腺（HG）、三分之一腺（1/3G）和六分之一腺（1/6G）的计划，以及评估对这些子体积之一进行加量治疗WG（WG + HG、WG + 1/3G、WG + 1/6G）的计划。分析的剂量学参数包括靶区D90%、V100%、V150%、膀胱（B）、直肠（R）、尿道（U）的D0.1、1和2cc、尿道V75%以及对侧HG的V50%。采用双尾t检验比较均值，p值小于0.05被认为具有统计学意义。
所有病例均达到靶区目标（D90 > 100%且V100 > 97%）。与WG计划相比，所有方法均实现了显著的危及器官剂量降低。1/6G与WG计划相比，剂量降低幅度最大，平均膀胱D2cc为24.7%对64.8%，直肠D2cc为32.8%对65.3%，尿道D1cc为52.1%对103.8%，V75为14.5%对75%（所有比较p < 0.05）。
使用HDR聚焦近距离放射治疗可显著降低危及器官的剂量。治疗逐渐缩小的子体积可实现的剂量降低幅度表明有可能降低发病率，但对发病率和肿瘤控制的临床影响仍有待研究。
