The relationship between medical diagnostic requirements and limiting values of technical and physical parameters for image production

In order to make radiographs comparable, the following requirements should be met: (a) representation in determined projections (''standard projections''), (b) imaging as ''harmonic image'' in the whole contrast scale of parts important for the diagnosis of the radiograph (''dominants''), (c) adjustment of mean optical density to the optimal contrast sensitivity of the eye, (d) extensive elimination of disturbing influences (e.g. motion, scattered radiation, veiling glare), and (e) reduction of the radiation exposure to values at which image details and critical structures are still perceptible. The influence of these parameters on the quality of the radiograph by changes in the projection, mean optical density, object latitude, contrast of details, exposure time and contrast transfer will show what can be claimed for an ''optimal'' radiograph and what deviations from optimal value can be accepted. (author)