Radiation safety considerations in GliaSite 125I brain implant procedures

The traditional approach to treatment of certain malignant brain tumors involves permanent implantation of I seeds sequential to tumor's resection. This approach has recently been changed for patients with unifocal recurrent gliomas. What began during the 1990's as a large clinical trial utilizing GliaSite Radiotherapy System, is currently becoming standard of care. This radiotherapy system consists of an inflatable balloon catheter, 2, 3, or 4 cm diameter, which is surgically placed in the tumor resection cavity; its positioning and the level of conformity within the cavity are verified via MRI imaging with contrast. The balloon is then filled with appropriate volume of I in the liquid form. Radiation treatment prescription dose ranges from 40 to 60 Gy (4,000 to 6,000 rads). This is accomplished by allowing 2.77 to 16.6 GBq (75 to 450 mCi) of I to remain in the balloon for 3-5 d. Numerous technical, dosimetric, and logistical considerations arise when handling large quantities of iodine necessary to perform GliaSite procedures. They require coordination of efforts of several hospital departments and the institution's RSO-in our case, two RSOs, at the University of Colorado Hospital and University of Colorado Health Sciences Center hold separate radioactive materials licenses. Based on our experiences and those of others, we conclude that, with appropriate guidance and care, these procedures can be performed safely without excessive restrictions.