Dosimetric analysis of 3D-printing template assisted and CT-guided ¹²⁵I seed implantation for treatment of soft tissue sarcoma

Objective: To compare the dose distribution of postoperative plans with preoperative plans of 3D-printing template (coplanar and non-coplanar) assisted and CT-guided ¹²⁵I seed implantation for the treatment of soft tissue sarcoma, and to explore the accuracy of treatment at dosimetry level. Methods: From December 2015 to July 2017, 19 patients with soft tissue sarcoma (a total of 25 lesions) were treated with 3D printing template assisted and CT-guided ¹²⁵I seed implantation in Peking University Third Hospital. All patients underwent preoperative assessment, CT simulation orientation, preoperative planning, 3D-template printing, 3D-template reduction, needle and seed implantation, postoperative dosimetry assessment, postoperative care and follow-up. The preoperative and postoperative dosimetric parameters were conpared. Ten cases of soft tissue sarcoma in superficial trunk or limbs were screened. Preoperative planning of coplanar template and non-coplanar template were designed respectively. The dosimetric parameters of preoperative planning guided of two templates were compared. Results: Twenty-five 3D-printing templates were designed and constructed, and 25 lesions were totalled. There was no statistical difference between preoperative and postoperative dosimetric parameters. There was no statistical difference of the preoperative plan's dosimetric parameters between coplanar and non-coplanar in soft tissue sarcoma of superficial trunk/limbs. Conclusions: The validation of actual dose distribution in postoperative plans assisted by 3D-printing template in ¹²⁵I seed implantation showed that most of parameters could meet the expectation of preoperative plans, which indicated the improvement in accuracy for this new modality. For soft tissue sarcoma located in the superficial trunk/limbs, it was recommended to select the 3D-printing coplanar template firstly. (authors)