[Environmental radiation dose monitor after 125I radioactive seed implantation].

BACKGROUND & OBJECTIVE: Medical imaging-guided 125I radioactive seed implantation is a new method of mini-invasive therapy. As a component of combined therapy for malignant tumors, 125I implantation has benefits of minimal invasion, accurate position fixing, and certain clinical effects, and has been widely applied to treat tumors at present. Also the environmental phototoxis and radiation protection have been highly regarded. This study was to investigate the environmental radiation dose monitor after 125I radioactive seed implantation. METHODS: From Oct. 2004 to Dec. 2005, 20 patients with malignant tumors were randomly selected in this study after 125I radioactive seed implantation. Environmental radiation dose was detected right after operation and 2, 4 and 6 months later with gamma-ray equipment. RESULTS: With the increase of the distance from radioactive source, the radiation dose decreased quickly. The detected dose was close to a natural background radiation dose at a distance of 50 cm from radioactive source. With time passing, the environmental radiation dose was attenuated and the detected dose was close to natural background after 6 months. CONCLUSIONS: Addition to the isolation and shielding protection before and after 125I radioactive seed implantation, distance protection and time protection should be considered. With necessary strict protection, 125I implantation is safe to patients and environment.