Image quality improvements of electronic portal imaging devices by multi level gain calibration and temperature correction

Abstract

Stefan Huber a), c), Michaela Mooslechner a, b), Bernhard Mitterlechner b), Felix Sedlmayer a, b) and Heinz Deutschmann a, b)

a) Institute for Research and Development on Advanced Radiation Technology (radART), Paracelsus Medical University, Salzburg,
    Austria

b) University Clinic for Radiotherapy and Radio-Oncology, Salzburger Landeskliniken, Salzburg, Austria

High MV-imaging quality during the radiotherapy process with amorphous silicon flat panels is a major requirement for special applications as for example image guided radiotherapy as well as verification tasks. These detectors are exposed to high energetic radiation which damages especially the detector's electronics components and leads to a wide range of artifacts. According to former experiences, the non linearity dose response of pixels and the temperature have a major impact on the specific behaviour and characteristic of the panel, which has higher significance for older panels. Typically, amorphous silicon flat panels have to be replaced after 18 months due to increasing but unpredictable noise and subpanel-related artifacts that change during the day. With our approach we are correcting all these artifacts and increase the usage of the panel up to 4 years.