IMAGE QUALITY TESTS OF CONVENTIONAL AND DIGITAL RADIOGRAPHIC EQUIPMENT

The optimisation of image quality and at the same time the reduction of the absorbed dose to the patient is a main task for physicists and engineers involved in diagnostic radiology. A necessity for this is a good tool for evaluation of the image quality. A new test phantom, the Standard Test Phantom, for image quality optimisation and quality assurance is introduced. All test phantoms include a reference film obtained with an optimised system together with quantitative data. The Standard Test Phantom is designed for visual as well as quantitative evaluations of: spatial resolution, contrast, contrast detail, scatter to primary ratio, kV(p) estimation, test of coincidence between the light and the X ray fields, measuring of image intensifier size, pin-cushion distortion of image intensifier, determination of the contrast transfer function, simple test of automatic exposure control units (optical density as a function of object size), and the magnification ratio can be measured directly from the image. The results are shown by comparing mainly digital imaging techniques with conventional techniques. Suggestions for a quality assurance programme with the Standard Test Phantom are presented.