Imaging in Swivel Gaming Chair radiation therapy has become an important part of clinical routine.In order to evaluate and compare the image quality of verification images from different imaging modalities, one needs objective criteria like the modulation transfer function (MTF).The aim of our study was to compare the resolution properties of three generations of electronic portal imaging devices (EPIDs), namely one ORG COCONUT SMILES fluoroscopic-optical system and two different flat-panel imaging systems.