The accuracy and safety of CT-guided iodine-125 seeds implantation assisted by 3D non-coplanar template for retroperitoneal recurrent carcinoma.

Abstract

Purpose To investigate the accuracy, dosimetric parameters and safety of 3D-printing non co-planar template (3D-PNCT) assisted CT-guidance for radioactive iodine-125 (125I) seed implantation brachytherapy (RSI-BT) for retroperitoneal recurrent carcinomas. Methods and materials: We enrolled 15 patients with 17 retroperitoneal recurrent carcinomas after external beam radiotherapy (EBRT). All patients received CT-guided 125I RSI-BT assisted by 3D-PNCT successfully. We compared the original needles insertion position, angular and the needle tips distance deviations of preoperative plan with that of intra-operative in brachytherapy treatment-planning system (B-TPS). The dosimetric parameters of RSI-BT were evaluated on preoperative plan, intra-operative real-time plan and postoperative plan, including D90, D100, V100, V150 and V200. The quality assurance of RSI-BT evaluated on conformal index (CI), external index (EI), homogeneity index (HI) of the targets were compared among preoperative plan, intra-operative real-time plan and postoperative plan. The peri-operation complications and re-radiation related toxicity were assessed. Results The median follow-up was 8.2 months (range 1-18.5months). One patient lost follow-up after RSI-BT. 14 patients were assessed for response rate and toxicity. The mean entrance point distance deviation for all 165 needles was 4.50 ± 4.10 mm (range, 0–30). The mean angular deviation was 2.70 ± 3.00 degrees (range, 0–20). The needles tip distances deviation was 6.90 ± 6.00 mm (range, -30-28). D90 for preoperative plan, intra-operative plan and postoperative plan were 140.55 ± 23.93, 124.25 ± 28.04,128.98 ± 22.75. There was significant difference between D90 of preoperative plan with that of intraoperative plan (p = 0.036). Four patients reached CR, three patients reached PR, three patients were SD and three patients was PD. Four patients with middle pain became moderate, two with moderate pain relived completely after RSI-BT. The others parameters showed no differences among preoperative plan, intraoperative plan and postoperative plan. The perioperative complications were observed in four patients, including three patients of grade 1 and one patient of grade 2. No ≥ grade 3 side-effects were observed. Conclusion CT-guided 125I RSI-BT assisted by 3D-PNCT was a safe, accurate and feasible strategy for recurrent carcinomas located in retroperitoneal regions.