[Electronic portal imaging (EPI) on linear accelerator]

The EPI has become available recently in the Oncoradiological Centre of Budapest. The purpose of this paper is to review the construction and operation of the electronic portal imaging devices (EPIDs). The different EPID systems as well the EPID technique vs. portal films are compared. The advantages in patient set-up and the detection of the set-up errors are discussed. The use of the EPID technique in the clinical everyday practice is detailed. Recommendations of the set-up error correction for the most often occurring failures is given.