Taylor Peter K, Riegel Adam C
Northwell Health System, Department of Radiation Medicine, Center for Advanced Medicine, Lake Success, NY, USA.
Hofstra Northwell School of Medicine, Hempstead, NY, USA.
J Appl Clin Med Phys. 2018 Sep;19(5):383-388. doi: 10.1002/acm2.12404. Epub 2018 Jul 13.
Several nomograms exist for ordering palladium-103 seeds for permanent prostate seed implants (PSI). Excess seeds from PSIs pose additional radiation safety risks and increase the cost of care. This study compared five nomograms to clinical data from dynamic modified-peripheral intraoperative PSI to determine (a) the cause of excess seeds and (b) the optimal nomogram for our institution. Pre- and intraoperative patient data were collected for monotherapy PSIs and compiled into a clinical database. All patients were prescribed 125 Gy with dose coverage of D90% = 100% to the planning target volume (PTV) using Pd seeds with mean air-kerma strength ( ) of 2 U. Seeds were ordered based upon an in-house nomogram as a function of preoperative prostate volume and prescription dose. Preoperative prostate volume was assessed with transrectal ultrasound. If any of the following four conditions were not met: (a) preoperative volume = intraoperative volume, (b) D90% = 100%, (c) , and (d) seed ordering matched the in-house nomogram, then a normalization factor was applied to the number of seeds used intraoperatively to meet all four conditions. Four published nomograms, an in-house nomogram, and the normalized number of implanted seeds for each patient were plotted against intraoperative prostate volume. Of the 226 patients, 223 had excess seeds at the completion of their PSI. On average, 25.7 ± 9.9% of ordered seeds were not implanted. Excess seeds were separated into two categories, accounted-for excess, determined by the four normalization factors, and residual excess, assumed to be due to overordering. The upper 99.9% CI linear fit of the normalized clinical data plus a 5% "cushion" may provide a more reasonable nomogram for Pd seed ordering for our institution. Nomograms customized for individual institutions may reduce seed waste, thereby reducing radiation safety risks and increasing the value of prostate brachytherapy.
目前存在几种用于为永久性前列腺籽源植入（PSI）订购钯 - 103籽源的列线图。PSI中多余的籽源会带来额外的辐射安全风险并增加护理成本。本研究将五种列线图与动态改良周边术中PSI的临床数据进行比较，以确定（a）多余籽源的原因，以及（b）适合我们机构的最佳列线图。收集了单疗法PSI的术前和术中患者数据，并汇编成临床数据库。所有患者使用平均空气比释动能强度（ ）为2 U的钯籽源，规定给予125 Gy的剂量，计划靶体积（PTV）的D90% = 100%。根据内部列线图，将籽源作为术前前列腺体积和处方剂量的函数进行订购。术前前列腺体积通过经直肠超声评估。如果未满足以下四个条件中的任何一个：（a）术前体积 = 术中体积，（b）D90% = 100%，（c） ，以及（d）籽源订购与内部列线图匹配，则对术中使用的籽源数量应用归一化因子以满足所有四个条件。将四个已发表的列线图、一个内部列线图以及每个患者植入籽源的归一化数量与术中前列腺体积进行绘制。在226例患者中，223例在PSI完成时存在多余籽源。平均而言，订购的籽源中有25.7 ± 9.9%未被植入。多余籽源分为两类，即由四个归一化因子确定的已解释多余部分和假定由于订购过多导致的残余多余部分。归一化临床数据的99.9%上限置信区间线性拟合加上5%的“缓冲”可为我们机构的钯籽源订购提供更合理的列线图。为个别机构定制的列线图可能会减少籽源浪费，从而降低辐射安全风险并提高前列腺近距离治疗的价值。
