| Popis: |
An experimental set-up of a selenium-based detector with a scanning fan-beam exposure and improved spatial resolution has been realized. The imaging performance in terms of MTF, image noise and signal-to-noise (S/N) ratios (NEQ,DQE) is measured as a function of dose and spatial frequency for 40 kVp and 50 kVp tungsten X-ray spectra. The measured S/N-performance is interpreted in terms of a simple model which is used to study the effect of geometric magnification techniques and the behaviour of the system for various beam qualities. The object detectability for weak and high contrast objects has been calculated for different beam qualities. The results are compared with the data of high-resolution screen-film systems. |
