Study of the readout of a storage phosphor screen with APDs

We have built a readout system using avalanche photodiodes as a photodetector in computed radiography systems based on storage phosphor screens. The advantages of APDs are the higher quantum-efficiency at 390 nm and their compactness allowing a better light collection efficiency. The APD shot noise and amplifier noise were determined and compared with the intrinsic image noise. The imaging performance of the complete readout system has been analyzed by measuring the light collection efficiency, signal-to-noise ratio, modulation transfer function and noise power spectrum.