CT guided coplanar template assisted in the treatment of metastatic or recurrent chest wall malignant tumor with ¹²⁵I seed implantation

Objective: To evaluate the dosimetry accuracy and clinical efficacy of ¹²⁵I radioactive seed implantation using coplanar template (CPT) in the treatment of metastatic or recurrent chest wall tumor. Methods: Thirty-one patients with metastasis or recurrence of chest wall tumor, who had been diagnosed with pathology between July 2005 and July 2015, were retrospectively studied. All patients underwent CPT-assisted ¹²⁵I radioactive seed implantation. Brachytherapy radiation treatment planning system (BTPS) was used to make preoperative plans, and the prescribed dose (PD) was 110 Gy. CPT was used to assist CT guided ¹²⁵I radioactive seeds implantation. Dose evaluation was performed immediately after implantation. The difference of dose parameters was compared between preoperation and postoperation, including D₉₀, D₁₀₀, V₉₀, V₁₀₀ and the numbers of seeds. Postoperative chest CT was conducted regularly to assess the treatment efficacy based on the response evaluation criteria in solid tumors (RECIST Version 1.1). The patients were followed up till July 2016. Results: All patients went through implantation procedure successfully and there was no significant statistical difference between preoperative and postoperative dose parameters (P > 0.05). The conformal index(CI) was 0.951 ± 0.13, external index(EI) was 6.5% ± 0.9%. Six months after implantation, CR, PR, SD and PD were 25.8% (8/31), 51.6% (16/31), 6.5% (2/31) and 16.1% (5/31), respectively. The effective rate was 77.4%, and local control rate was 83.9% (26/31). Skin pigmentation occurred in 13 patients during the follow-up period, without any special treatment. Conclusions: The auxiliary of CPT in the treatment of metastatic or recurrent chest wall tumor under the guiding of CT could achieve quality control, safety and effectiveness. (authors)