Waterman F M, Yue N, Corn B W, Dicker A P
Department of Radiation Oncology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA.
Int J Radiat Oncol Biol Phys. 1998 Jul 15;41(5):1069-77. doi: 10.1016/s0360-3016(98)00152-7.
To characterize the magnitude and duration of post-implant edema following the implantation of I-125 or Pd-103 seeds into the prostate and to investigate its effect on the CT-based calculation of the total dose delivered by the implant.
A pre-implant CT scan and 3 to 5 serial post-implant CT scans were obtained on 10 patients who received either I-125 or Pd-103 seed implants. None of the patients received hormone therapy. The magnitude and duration of edema were determined from the change in the spatial distribution of the implanted seeds as the edema resolves. Dose volume histograms were compiled to determine the percentage of the prostate volume that received a dose equal to, or greater than, the prescribed dose.
The magnitude of the edema, expressed as the ratio of the post- to pre-implant volume on the day of the procedure, ranged from 1.33 to 1.96 (mean 1.52). The edema decreased exponentially with time; however, the edema half-life (time for the edema to decrease by 1/2) varied from 4 to 25 days (mean 9.3 days). As the edema resolved, the percentage of the prostate that received a dose equal to or greater than the prescribed dose increased by at least 7% in 7 of the 10 patients and increased by more than 15% in 2. In those patients in whom dose coverage was unaffected by the resolution of edema, more than 90% of the prostate was covered by the prescribed dose in the initial CT scan.
Post-implant edema increased the prostate volume by factors which ranged from 1.33 to 1.96 (mean: 1.52). The edema resolved exponentially with an edema half-life which varied from 4 to 25 days (mean: 9.3 days). Edema had a significant effect on the post-implant dosimetry in 7 of 10 cases. Factors that affect the impact of edema on the dosimetry are the magnitude of the edema and the planned margin between the prescribed isodose line and the periphery of the prostate.
描述将I-125或Pd-103种子植入前列腺后植入后水肿的程度和持续时间，并研究其对基于CT计算植入物所输送的总剂量的影响。
对10例接受I-125或Pd-103种子植入的患者进行植入前CT扫描及3至5次植入后连续CT扫描。所有患者均未接受激素治疗。随着水肿消退，根据植入种子空间分布的变化确定水肿的程度和持续时间。编制剂量体积直方图以确定接受等于或大于处方剂量的前列腺体积百分比。
水肿程度以术后当天与植入前体积之比表示，范围为1.33至1.96（平均1.52）。水肿随时间呈指数下降；然而，水肿半衰期（水肿减少一半的时间）从4天到25天不等（平均9.3天）。随着水肿消退，10例患者中有7例接受等于或大于处方剂量的前列腺百分比至少增加了7%，2例增加超过15%。在那些剂量覆盖不受水肿消退影响的患者中，初始CT扫描中超过90%的前列腺被处方剂量覆盖。
植入后水肿使前列腺体积增加了1.33至1.96倍（平均：1.52）。水肿呈指数消退，水肿半衰期从4天到25天不等（平均：9.3天）。10例中有7例水肿对植入后剂量测定有显著影响。影响水肿对剂量测定影响的因素是水肿程度以及处方等剂量线与前列腺周边之间的计划边界。
