New miniaturized cesium-137 for needle implants

Slender cesium-137 sources have been derived for afterloading implants which simulate the radium implants employed in the past. The sources have active lengths of 3, 4 or 5 cm with 0.66 mg Ra equivalent of 137Cs/cm. The overall length of each source consists of an additional 6 cm of inactive platinum-iridium tubing which encapsulates the sources. When not in use, these sources can be kept safely in an appropriate lead shield in the Radiotherapy Department to be available on demand. The sources are thin enough, 0.7 mm in diameter, to fit in the lumen of an 18 gauge needle. The implant is done in the operating room with hollow tubes which are loaded with dummy wires simulating the sources so that appropriate X-ray studies can be made. There is no radiation hazard during these procedures, or during transportation of the patient, since afterloading with the 137Cs source is done in the patient's own room. (author)