Isoray, Inc., through its subsidiary, IsoRay Medical, Inc., develops, manufactures, and sells isotope-based medical products and devices for the treatment of cancer and other malignant diseases in the United States and internationally. The company offers CS-1 Cesium-131 brachytherapy seeds for the treatment of prostate, brain, lung, head and neck, gynecological, pelvic/abdominal, and colorectal cancers. It sells its products to facilities or physician practices that utilize various surgical facilities. Isoray, Inc. was founded in 1998 and is based in Richland, Washington.