Image Quality In Selenium-Based Digital Radiography

Capacitive sensing of x-ray generated charge images on amorphous selenium layers represents an attractive technique for the electronic recording of projection radiographs. In order to evaluate the practical limits of image quality with such a selenium detector we have set up a laboratory system that allows the recording of small size (70 x 70 mm2) radiographic images. We have measured MTF and noise power spectra and have calculated from these data noise equivalent quanta (NEQ) and detective quantum efficiency (DQE) as a function of dose and spatial frequency. On the basis of these quantities the imaging performance of the system is discussed.