Quality Control of Portal Imaging with PTW EPID QC PHANTOM

Purpose: Quality assurance (QA) and quality control (QC) of different electronic portal imaging devices (EPID) and portal images with the PTW EPID QC PHANTOM ® . Material and Methods: Characteristic properties of images of different file formats were measured on Siemens OptiVue500aSi ® , Siemens BeamView Plus ® , Elekta iView ® , and Varian PortalVision™ and analyzed with the epidSoft ® 2.0 program in four radiation therapy centers. The portal images were taken with Kodak X-OMAT V ® and the Kodak Portal Localisation ReadyPack ® films and evaluated with the same program. Results: The optimal exposition both for EPIDs and portal films of different kind was determined. For double exposition, the 2+1 MU values can be recommended in the case of Siemens OptiVue500aSi ® , Elekta iView ® and Kodak Portal Localisation ReadyPack ® films, while for Siemens BeamView Plus ® , Varian PortalVision™ and Kodak X-OMAT V ® film 7+7 MU is recommended. Conclusion: The PTW EPID QC PHANTOM ® can be used not only for amorphous silicon EPIDs but also for images taken with a video-based system or by using an ionization chamber matrix or for portal film. For analysis of QC tests, a standardized format (used at the acceptance test) should be applied, as the results are dependent on the file format used.