Imaging plates are exposured similar to radiographic films. Colour centres formed during X-ray exposure can be detected directly by a Laser Scanner without any development process. After read out the imaging plates could be erased and are reusable up to 1000 times. The image quality reached by the film is used as evaluation criterion for the imaging plates. Investigations are presented characterising the contrast sensitivity, dynamic range and linearity. considering the spectral response of the imaging plates combinations of screens (Pb, Fe) together with imaging plates are studied in regard of their amplification or filtering behaviour. Measuring the scatter ratio and the specific contrast for steel the screen thicknesses are determined, necessary for equivalent values reached by the application of films according to code.

Additionally the obtained geometric resolution was measured depending on the energy. These measurements were based on the double wire IQI CERL B, a SIEMENS star and MTF calculations from a Pt edge. Signal-to-noise ratios depending on the dose for different energies have been derived from the evaluation of step wedge images. These values are presented in relation to the exposure time and the contrast sensitivity. A discussion is given for the influence of the determined parameters on the image quality for weld inspection. The presented data are based on a system built for biomedical auto radiography (BAS 2000, Fuji-Film) working at 100 micron geometric resolution and a logarithmic detector system (10 Bit dynamic resolution). Our investigations show that several parameters are limited by the scanning system. Improvements are to be expected for higher resolving systems (i. e. 50 microns, 14 Bit).