The Effect of Photon Transport on the Performance of Electronic Imaging Detectors

The use of electronic imaging detectors in radiography and fluoroscopy allows the spatial variation of transmitted radiation intensity to be measured directly and stored in electronic devices for subsequent analysis and display. By eliminating the conventional use of photographic film in conjunction with scintillation screens or image intensifiers, potential cost and performance benefits can be accrued. Most electronic imaging detectors considered to date have poor resolution characteristics. However, this is usually due to problems in fabrication and charge readout and not to fundamental limits in performance. Fundamental limitations in the performance of electronic detectors result from charge deposited away from the position where an X-ray photon is initially absorbed and are dictated by the material composition of the detector. The charge transport arises from either secondary photons or secondary electrons. In this paper, we present preliminary results on computer calculations of the effects of secondary radiation transport on the intrinsic imaging characteristics of electronic imaging detectors as a function of their elemental composition.