This document describes how to transfer treatment beam setup information from the Prism treatment planning system to Elekta accelerators over a computer network. The transfer over the network is accomplished using an industry-standard protocol called DICOM-RT. The Prism DICOM-RT facility can assemble several (or many) individual Prism beams into a group that the Elekta accelerators handle as a single multisegment ``step-and-shoot'' beam. In this way, it can support IMRT (intensity modulated radiation therapy) treatment techniques. The Prism DICOM-RT facility prints a chart that describes the data that was sent, so users can relate the original data on the Prism side to the data as it appears on the Elekta side. The Prism DICOM-RT facility writes log files that record each transfer attempt and indicate which data was transferred. These may be useful for quality assurance and troubleshooting.