Abstract
The demand for adequate image quality with low radiation doses for patients has greatly increased. This is especially true in the case of position verification in radiotherapy which requires a high number of images per patient. This study presents a physical characterisation of a new clinical detector based on a thick layer of structured Thallium activated Cesium Iodide. We made a critical appraisal of its performance for the first time and determined its detective quantum efficiency (DQE) by acquiring the pre-sampling modulation transfer function and normalised noise power spectrum (NNPS). The investigation was conducted with the application of three x-ray beam qualities in compliance with the International Electrotechnical Commission (IEC 62220-1:2003) standard. The spatial resolution and NNPS results led to relatively high DQE values at all energies: DQEs (0.5) were 0.46 for 54kV, 0.52-0.56 for 74kV and 0.55-0.59 for 92kV.