Methods for characterization of digital, imageproducing detectors within medical X-ray diagnostics

Abstract: Since the end of the 1900th century ionized radiation, foremost X-ray radiation, have been used, with great success, within the medical field as a method for diagnostics as well as for therapeutically treatments. When it comes to X- ray diagnostics, the analogue film, detector and display medium have, in principle, been used the whole time. This is now rapidly changing, in a way that makes digital detectors dominate instead. Within the area of medical treatment, this means that methods must progress and be developed to measure and secure the quality of the imaging systems in a quick, easy and accurate way. The ability of the imaging system to reproduce the measured objects in a natural manner can be characterized by a number of different parameters such as; ESF (Edge spread function), LSF (Line spread function), MTF (Modulation transfer function), NPS (Noise power spectrum), and DQE (Detective quantum efficiency). These parameters can be received for each detector through experimental measurements of a sharp edge. The starting point of the project is the suggestions that are stated in the standard form IEC (622 20-1) determination of detective quantum efficiency, which was published by the end of 2003. Purpose of the project: • Construct a test object (phantom) that can generate a sharp edge in the X- ray image. • Develop a program code in the high-level language MATLAB for determination of earlier mentioned parameters, MTF and DQE in particular. • Work out radiation geometry, suitable for the purpose. • Verify the usability through practical measurements on already existing clinical equipment at the hospital in Blekinge. • Study the effect of radiation energy, dose of radiation, detector direction, spatial frequency, variation of sampling of the edge spread function (ESF), etc. • Compare gained results with relevant literature. The practical meaning of the present case project is to: • Make a clinically usable method for the quality safety of digital, medical X- ray equipment available at the hospital in Blekinge. • Transfer, from the hospital in Blekinge to the Blekinge Institute of Technology, competence within medical radiation physics and medical technology, which could be interesting since the University is considering increasing their commitment within this area. • The method can be spread within the informal co-operation, concerning medical radiation physics that is present within the hospitals outside the University districts in the southern region.