Efficacy and dosimetric analysis of CT-guided 125I seed implantation assisted by 3D-printed coplanar template in the treatment of metastatic tumors of chest wall / 中华放射医学与防护杂志

ABSTRACT

Objective:To investigate the technical method and clinical efficacy of CT-guided radioactive 125I seed implantation (RISI) assisted by 3D-printed coplanar template(3D-PCT) in the treatment of metastatic tumors of chest wall, and analyze the influence of dosimetric parameters on the treatment efficacy. Methods:A retrospective analysis was conducted for 55 patients with metastatic tumors of chest wall treated with 3D-PCT-assisted 125I radioactive seed implantation in Tengzhou Central People′s Hospital from January 2014 to March 2021.Preoperative plans were made using a brachytherapy treatment planning system, and dosimetric parameters were assessed at 3d after surgery. During regular CT reexaminations after surgery, the local control rate and overall survival (OS) rate were calculated and the pain relief degree and complications were assessed. The Logrank test and Cox regression were used for univariate and multivariate analyses of local control time (LCT). Meanwhile, receiver operating characteristic (ROC) curves were plotted to analyze the critical values of dosimetric parameters and to predict the LCT. Results:The 1-, 2-, and 3-year OS rates ofthe 55 patients were 72.7% (40/55), 21.8% (12/55), and 16.4% (9/55), respectively.The local control rates of 3, 6, 12, and 24 months were 96.4%(53/55), 86.5%(45/52), 85.0%(34/40), and 91.7%(11/12), respectively. There was no statistically significant difference between postoperative and postoperative dosimetric parameters of GTV, particle number, D90, D100, V100, V150, V200, CI, EI, and HI ( P> 0.05). Compared with postoperative V90, the postoperative V90 decreased with a statistically significant difference( P=0.006). As indicated by the univariate Cox regression analysis, the pathological grade, D90, D100, V90, and V200had significant effects on the LCT( P<0.05). Among them, the pathological grade and D90 were independent influencing factors of the LCT, while the other factors showed no statistically significant difference according to the multivariate Cox regression analysis.The LCT of patients with D90≥127 Gy was significantly longer than that of patients with D90<127 Gy (χ 2=16.61, P=0.000). The pain relief rate was 80.8%(21/26) after three months. Five cases suffered from grade Ⅰ-Ⅱ radioactive dermatitis and one case experienced grade Ⅲ radioactive dermatitis. Conclusions:The 3D-PCT-assisted CT-guided 125I radioactive seed implementation can achieve precise and controllable dose and definite efficacy in the treatment of metastatic tumors of chest wall, with few complications.The LCT was remarkably prolonged in the case of D90≥127 Gy, and D90 is an independent influencing factor of the LCT.