Single High-dose Brachytherapy for Giant Osteosarcoma Masses

This study is a prospective, single-arm, phase II, single-center study. Patients with locally unresectable giant osteosarcoma masses who meet the criteria are enrolled in the experimental group, and all patients receive a single dose of 10Gy of implantable brachytherapy. Record treatment-related acute events during and after treatment. Follow up on survival and local control after treatment ends, marking the end of the trial treatment.