Performance evaluation of computerized treatment planning systems for radiotherapy: external photon beams

A program for verifying the accuracy of any computerized treatment planning system for radiotherapy requires the use of suitable tests. A representative protocol for performing such an evaluation for external photon beams is given. Data are presented documenting the need for such a protocol. An important benefit of carrying out a verification protocol as outlined is that the user appreciates the limitations of the system as well as the most appropriate ways in which to operate the system to insure accurate data in unusual geometries.