Clinical experience with long half-life and low-energy encapsulated radioactive sources in cancer radiation theapy.

Abstract

THE TREATMENT of localized cancer by-small radioactive sources permanently placed in the tissue is generally recognized as an effective modality of radiation therapy. In the past ten years, we had the opportunity at Memorial Hospital to use various radioisotopes for permanent interstitial implants in cancer patients. These radioisotopes may be divided into two groups: those with short half-lives, radon 222 (3.8 days) and gold 198 (2.7 days); and those with long half-lives, iridium 192 (74 days) and iodine 125 (60 days). The radioisotopes with long half-lives, iridium 192 and iodine 125, present a number of practical advantages for permanent implantation. The first advantage is the greater availability of the seeds. With radon-222 and gold-198 seeds, the activity decreases so rapidly that the seeds must be ordered for a specific day and usually have to be discarded if they cannot be used within a day or two. This fact limits permanent implants with radon-222 and gold-198 seeds in most hospitals to tumors w...