Dosimetry verification of 3D-printed individual template based on CT-MRI fusion for radioactive (125)I seed implantation in recurrent high-grade gliomas

PURPOSE: To verify the accuracy and efficacy of three-dimensional printing individual template (3D-PIT) with computed tomography-magnetic resonance imaging (CT-MRI) fusion for radioactive iodine-125 ((125)I) seed implantation in high-grade brain gliomas. MATERIAL AND METHODS: Between June 2017 and June 2018, 16 patients with recurrent high-grade gliomas (rHGG) underwent radioactive seed implantation with 3D-PIT. The prescribed dose was 120-140 Gy. We compared the dose distribution of the postoperative plan with the preoperative plan. Dose parameters included D(90), V(100), V(200), conformity index (CI), and external index of the target volume (EI). Local control and early complications were also analyzed. RESULTS: Sixteen treatment areas were reported in our study. Median gross tumor volume (preoperative) of patients was 64.2 cm(3), median needle number was 8, and median number of implanted (125)I seeds was 60. For postoperative plans, the median D(90), V(100), and V(200) was 152.1 Gy, 96.8%, and 49.1%, respectively, and 151.7 Gy, 97.0%, and 48.9%, respectively, in preoperative plans. Comparing with the preplanned cases, the dose of the target volume was slightly higher; the high-dose area of the target volume was larger in postoperative cases, but the difference was not statistically significant (p > 0.05). Actual dose conformity of the target volume was greater than preplanned, and the difference was not statistically significant (p > 0.05). Local control was 81.25% and 75% at 3 and 6 months after implantation, respectively. No serious early toxicities were observed. CONCLUSIONS: 3D-PIT based on the CT-MRI fusion images can result in good accuracy for positioning and dose distribution in radioactive seed implantation for treatment of rHGG.