Accuracy and dosimetric parameters comparison of 3D-printed non-coplanar template-assisted computed tomography-guided iodine-125 seed ablative brachytherapy in pelvic lateral recurrence of gynecological carcinomas

PURPOSE: To investigate the accuracy of needle distribution and dosimetric parameter differences of 3D-printing non-coplanar template (3D-PNCT)-assisted computed tomography (CT)-guided iodine-125 seed ablative brachytherapy ((125)I-SAB) in gynecological cancer patients with non-central pelvic recurrence between pre-operative plan and post-operative plan. MATERIAL AND METHODS: Thirty-eight patients with forty-one non-central pelvic recurrent gynecological carcinomas after radiotherapy were enrolled in this study. All patients received 3D-PNCT-assisted CT-guided (125)I-SAB from January 2016 to January 2019. The position, angle, and depth of seed needles were measured in both pre-operative plan and intra-operative real-time plan in brachytherapy treatment planning system (B-TPS). Dosimetric parameters of D(90), D(100), V(100), V(150), and V(200) as well as quality parameters of conformal index (CI), external index (EI), and homogeneity index (HI) were compared between pre-operative plan and post-operative plan. Peri-operation complications and radiation-related toxicity were assessed. RESULTS: Median follow-up time was 12 months (range, 5-34 months). Prescribed dose was 100-170 Gy (median, 120 Gy). Radioactivity of (125)I seed was 0.4-0.7 mCi (median, 0.55 mCi). Mean depth deviation for 499 needles was 0.8 ±1.0 cm. Mean angular deviation was 2.2 ±2.1 degrees. Mean tip distance deviation of needles was 0.4 ±0.3 cm. There were significant differences between pre-operative and post-operative plans in CI (p = 0.001) and EI (p = 0.005). No significant differences were shown in D(90), D(100), V(100), V(150), V(200), and HI between pre-operative and post-operative plans. Only few patients suffered from ≤ grade 2 toxicities. CONCLUSIONS: 3D-PNCT-assisted CT-guided (125)I-SAB is safe and feasible for non-central pelvic recurrence of gynecological cancer. All complications are tolerable and mild.