Radnostix (formerly International Isotopes) is a small specialty manufacturer of radioisotope-based products for medical, industrial, and research applications, operating out of Idaho with about 45 employees. The company's core product is a generic sodium iodide I-131 drug — the only FDA-approved domestic U.S. version — which Radnostix sells to radiopharmacies that compound and dispense it to clinicians treating hyperthyroidism and thyroid cancer. Radnostix also manufactures cobalt-60 sealed sources for radiation therapy and industrial sterilization, and calibration and reference sources used to calibrate SPECT and PET imaging equipment in nuclear medicine clinics. These calibration products generate recurring revenue because radioactive isotopes decay predictably, requiring customers to replace sources roughly every 18 months to two years. The company operates five segments: Theranostics Products (I-131 and radiopharmaceuticals), Cobalt Products, Calibration & Reference Products, Medical Devices, and a dormant Fluorine Products segment tied to a suspended uranium de-conversion facility. The Medical Devices segment is early-stage, currently distributing third-party equipment while developing the EasyFill Automated Capsule System — a robotic I-131 encapsulation device for radiopharmacies — targeting a 2026-2027 launch. Radnostix intends EasyFill to function alongside its I-131 supply in a razor-and-blade model, deepening radiopharmacy relationships and accelerating I-131 market share gains. Barriers to entry across all segments are high, given the NRC and FDA licenses, specialized facilities, and regulatory expertise required to handle radioactive materials.