  In this work, we have studied the MTF optimisation relative to the detector
aperture of four digital dental X-ray image systems: 1) Digora and Denoptix
systems, based on PSPL detectors; 2) CDR and Sens-A-Ray 2000, based on CCD
detectors. The MTF was evaluated by ERF method and linearized as a Gaussian
process. The CCD based systems presented Gaussian characteristics. The PSPL
based systems presented a composition of two Gaussian processes. We conclude
that one process is due to the laser and stimulated light scattering inside the
PSPL plate and the other is due to the laser beam focal aperture. Matching
focal aperture to laser scattering allows the optimization of the PSPL systems
resolution. An optimal pixel width found to be 62 um.
