Selenium-75: a potential source for use in high-activity brachytherapy irradiators

A study was made to find a high-specific-activity radioisotope having a longer half-life and lower gamma-ray energies than 192Ir in order to replace 192Ir in high-activity afterloading brachytherapy devices. Based upon a number of considerations, 75Se was selected. The present paper describes the physical properties of 75Se, its method of production, and the properties of an encapsulated source that was fabricated to prove the accuracy of our initial calculations.