Potters Louis, Calugaru Emel, Jassal Anup, Presser Joseph
New York Prostate Institute, South Nassau Communities Hospital, Oceanside, NY 11572, USA.
Int J Radiat Oncol Biol Phys. 2006 Jul 15;65(4):1014-9. doi: 10.1016/j.ijrobp.2006.02.003. Epub 2006 May 6.
To evaluate the correlation of real-time dynamic prostate brachytherapy (RTDPB) dosimetry and traditional postimplant dosimetry for permanent prostate brachytherapy.
A total of 164 patients underwent RTDPB for clinically confined prostate cancer. Of these 164 patients, 45 were implanted with 103Pd and 119 with 125I. Additionally, 44 patients underwent combined external beam radiotherapy and brachytherapy and 120 patients underwent brachytherapy alone. The postimplant dosimetry with computed tomography was performed at 4 weeks and compared with the RTDPB dose plan using the intraclass correlation coefficient. The millicurie/gram of the prostate volume and the percentage of the minimal dose to 90% of the prostate relative to the prescribed implant dose (D90%) of the RTDPB patients was compared with 400 patients treated with a free-seed technique.
The mean D90% achieved in the operating room and on the 3-week dose plan was 109% (range, 93-139%) and 105% (range, 88-140), respectively. The mean percentage of prostate volume receiving 100% of the prescribed minimal peripheral dose (V100) achieved in the operating room and on the 3-week dose plan was 93% (range, 78-98%) and 91% (range, 64-98%), respectively. The intraclass correlation coefficient for each calculated relationship was 0.586 for D90 (p<0.001), 1.19 for V100 (p=0.135), 0.692 for the urethral D90 (p<0.001), 0.602 for the maximal rectal dose (p<0.001), 0.546 for D90 with 125I (p<0.001), and 0.565 for D90 with 103Pd (p<0.001). A 12% decrease was noted in the millicurie/gram of the isotope, with a 2.5% increase in the D90 comparing RTDPB and the free-seed technique.
The results of this study demonstrated a correlation between the dose assessment obtained intraoperatively and postoperatively at 3 weeks. With reliable dose data available in the operating room, our results question the need for routine postimplant dose studies. Furthermore, patients treated with RTDPB received less radioactivity per gram of the prostate with a corresponding small increase in the D90. Future analyses will assess variations in the inverse dose planning rules and the clinical correlation of patients undergoing RTDPB vs. older techniques for toxicity and biochemical outcomes.
评估永久性前列腺近距离放射治疗中实时动态前列腺近距离放射治疗（RTDPB）剂量测定与传统植入后剂量测定之间的相关性。
共有164例临床局限性前列腺癌患者接受了RTDPB治疗。在这164例患者中，45例植入了103Pd，119例植入了125I。此外，44例患者接受了外照射放疗与近距离放射治疗联合治疗，120例患者仅接受了近距离放射治疗。在4周时进行了基于计算机断层扫描的植入后剂量测定，并使用组内相关系数与RTDPB剂量计划进行比较。将RTDPB患者的每克前列腺体积的毫居里数以及前列腺最小剂量相对于规定植入剂量（D90%）的90%的百分比与400例采用自由籽源技术治疗的患者进行了比较。
手术室和三周剂量计划时实现的平均D90%分别为109%（范围93 - 139%）和105%（范围88 - 140）。手术室和三周剂量计划时接受规定最小周边剂量100%（V100）的前列腺体积的平均百分比分别为93%（范围78 - 98%）和91%（范围64 - 98%）。每个计算关系的组内相关系数，D90为0.586（p<0.001），V100为1.19（p = 0.135），尿道D90为0.692（p<0.001），最大直肠剂量为0.602（p<0.001），125I的D90为0.546（p<0.001），103Pd的D90为0.565（p<0.001）。与自由籽源技术相比，RTDPB时每克同位素的毫居里数下降了12%，D90增加了2.5%。
本研究结果表明术中与术后3周获得的剂量评估之间存在相关性。由于手术室可获得可靠的剂量数据，我们的结果对常规植入后剂量研究的必要性提出了质疑。此外，接受RTDPB治疗的患者每克前列腺接受的放射性较少，而D90相应有小幅增加。未来的分析将评估逆向剂量规划规则的变化以及接受RTDPB治疗的患者与旧技术在毒性和生化结果方面的临床相关性。
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