RADPLANET is a functioning LAN (Local Area Network) designed to integrate the many and varied facilities of a university medical center radiology department (Department of Radiation Sciences) into an efficient unified resource providing state-of-the-art diagnostic capabilities and delivering precision radiotherapy. RADPLANET links diagnostic work stations, radiation-therapy planning work stations, and therapy machine stations into an integrated whole. The RADPLANET project exploits technology currently evolving in the PACS (Picture Archiving and Communicating Systems) community but also addresses digital image networking requirements peculiar to radiation therapy. RADPLANET is designed as a modular, expandable, piecemeal updatable system in order to incorporate new, more cost-effective technology as it becomes available and to provide new resources to meet the needs of a growing department and an increasingly sophisticated medical profession. The paper discusses design criteria and rationale, current status of the network, and plans for continuing expansion and enhancement.