Stock R G, Lo Y C, Gaildon M, Stone N N
Department of Radiation Oncology, Mount Sinai School of Medicine, New York, NY 10029-6574, USA.
Int J Radiat Oncol Biol Phys. 1999 Sep 1;45(2):385-9. doi: 10.1016/s0360-3016(99)00209-6.
Combined brachytherapy of the prostate and external beam irradiation (EBRT) of the prostate and seminal vesicles (SV) is becoming a popular treatment for high-risk prostate cancer. Dose-volume histogram (DVH) analysis of the SV in patients undergoing this treatment was performed to determine the dose distribution to the SV and the adequacy of this treatment in patients with potential SV involvement.
Twenty-five consecutive patients were treated with a Pd-103 implant of the prostate alone and 45 Gy of EBRT to the prostate and SV. Attempts were not made to implant the SV but seeds were routinely placed at the junction of the prostate and SV. All patients underwent CT-based postimplant dosimetric analysis 1 month after implantation. As part of this analysis, DVH were generated for the prostate and total SV volume (SVT). In addition, the SV was divided into 6-mm-thick volumes identified as SV1, SV2, SV3, SV4, and SV5 starting from the junction of the prostate and SV and extending distally. DVH were also generated for these structures. Delivered dose was defined as the D90 (dose delivered to 90% of the organ on DVH).
The median volumes in cc of the prostate, SVT, SV1, SV2, SV3, SV4, and SV5 were 34.33, 9.75, 2.7, 3.48, 2.92, 3.18, and 1.96 respectively. The SVT contained from 0-9 seeds (median 2). There was little dose delivered to the SVT and SV volumes from the implanted prostate. The median D90 values for the prostate, SVT, SV1, SV2, SV3, SV4, and SV5 were 8615 cGy, 675 cGy, 3100 cGy, 1329 cGy, 553 cGy, 246 cGy, and 67 cGy, respectively. The dose delivered to the prostate covered small percentages of SV. The percents of SV volumes covered by the prostate D90 were 11, 35, 3.3, 0, 0, and 0 for SVT, SV1, SV2, SV3, SV4, and SV5, respectively.
DVH analysis of the SV reveals that dose generated from an implanted prostate contributes little to the SV. Those patients at high risk for SV involvement may be undertreated with combined EBRT to prophylactic doses and prostate implantation.
前列腺近距离放射治疗联合前列腺及精囊外照射放疗（EBRT）正成为高危前列腺癌的一种常用治疗方法。对接受该治疗的患者的精囊进行剂量体积直方图（DVH）分析，以确定精囊的剂量分布以及该治疗对可能累及精囊的患者的充分性。
连续25例患者接受了单独的前列腺钯 - 103植入，并对前列腺及精囊进行45 Gy的EBRT。未尝试对精囊进行植入，但种子通常放置在前列腺与精囊的交界处。所有患者在植入后1个月接受基于CT的植入后剂量学分析。作为该分析的一部分，生成了前列腺和总精囊体积（SVT）的DVH。此外，从前列腺与精囊的交界处开始并向远端延伸，将精囊分为厚度为6 mm的体积，分别标识为SV1、SV2、SV3、SV4和SV5。也为这些结构生成了DVH。给予的剂量定义为D90（DVH上给予器官90%的剂量）。
前列腺、SVT、SV1、SV2、SV3、SV4和SV5的中位体积（单位：cc）分别为34.33、9.75、2.7、3.48、2.92、3.18和1.96。SVT包含0 - 9颗种子（中位值为2）。植入的前列腺对SVT和精囊体积的剂量贡献很小。前列腺、SVT、SV1、SV2、SV3、SV4和SV5的中位D90值分别为8615 cGy、675 cGy、3100 cGy、1329 cGy、553 cGy、246 cGy和67 cGy。给予前列腺的剂量覆盖精囊的比例较小。前列腺D90覆盖的SVT、SV1、SV2、SV3、SV4和SV5的精囊体积百分比分别为11%、35%、3.3%、0%、0%和0%。
精囊的DVH分析表明，植入前列腺产生的剂量对精囊贡献很小。那些精囊受累高危患者可能因联合EBRT至预防性剂量及前列腺植入而治疗不足。
