The accuracy and dosimetric analysis of 3D-printing non-coplanar template-assisted iodine-125 seed implantation for recurrent chest wall cancer

Purpose: To investigate the accuracy and dosimetry of 3D-printing non-coplanar template (3D-PNCT)-assisted computed tomography (CT)-guided iodine-125 seed implantation (I-125-SI) for recurrent chest wall cancer (rCWC). Material and methods: This was a retrospective study of 19 patients with 22 rCWC treated with 3D-PNCT-assisted CT-guided I-125-SI, from Mar 2017 to Mar 2020 in our institute. Results: Mean needle entrance deviation was 4.50 +/- 2.70 mm, mean angular deviation was 3.40 +/- 3.10 degrees, and mean depth deviation was 5.20 +/- 5.20 mm. No significant difference was found for dosimetric parameters (except conformity index) between pre-plan and post-plan; D-90, D-100, V-100, V-150, and V-200 were 157.74 +/- 24.23 and 151.71 +/- 33.62 (p = 0.228), 85.36 +/- 34.09 and 70.46 +/- 23.48 (p = 0.067), 0.93 +/- 0.04 and 0.90 +/- 0.07 (p = 0.068), 0.64 +/- 0.16 and 0.64 +/- 0.16 (p = 0.984), and 0.35 +/- 0.17 and 0.37 +/- 0.18 (p = 0.382) for pre-plan and post-plan, respectively. Conformity index, external index, and homogeneity index were 0.57 +/- 0.16 and 0.52 +/- 0.15 (p = 0.007), 0.73 +/- 0.55 and 0.79 +/- 0.53 (p = 0.096), and 0.31 +/- 0.15 and 0.30 +/- 0.14 (p = 0.504) for pre-plan and post-plan, respectively. Median follow-up time was 8 months (range, 3-30 months). Complete response was observed in 4/22 (18.1%), partial response in 13/22 (59.1%), stable disease in 4/22 (18.1%), and progression disease in 1/22 (4.5%) of the cancers. Among patients with pain before I-125-SI, pain relief rate was 87.5% (7/8). No peri-operative complications of more than grade 2 were observed. Conclusions: 3D-PNCT-assisted CT-guided I-125-SI may be safe and feasible as palliative therapy for non-surgical candidates and painful patients with rCWC.