IMAGE QUALITY TESTS OF CONVENTIONAL AND DIGITAL RADIOGRAPHIC EQUIPMENT

The optimisation of image quality and at the same time the reduction o f the absorbed dose to the patient is a main task for physicists and e ngineers involved in diagnostic radiology. A necessity for this is a g ood tool for evaluation of the image quality. A new test phantom, the Standard Test Phantom, for image quality optimisation and quality assu rance is introduced. All test phantoms include a reference film obtain ed with an optimised system together with quantitative data. The Stand ard Test Phantom is designed for visual as well as quantitative evalua tions of: spatial resolution, contrast, contrast detail, scatter to pr imary ratio, kV(p) estimation, test of coincidence between the light a nd the X ray fields, measuring of image intensifier size, pin-cushion distortion of image intensifier, determination of the contrast transfe r function, simple test of automatic exposure control units (optical d ensity as a function of object size), and the magnification ratio can be measured directly from the image. The results are shown by comparin g mainly digital imaging techniques with conventional techniques. Sugg estions for a quality assurance programme with the Standard Test Phant om are presented.