MODULATION TRANSFER-FUNCTION OF A DIGITAL DENTAL-X-RAY SYSTEM

An impulse train method to control aliasing was used to measure the mo dulation transfer function of a digital dental x-ray system (RVG 32000 ZHR, Trophy Radiologie, Vincennes, France). The detector of this syst em is composed of an intensifying screen, a fiber optics taper, and a charged couple device chip. The modulation transfer function could not be measured by impulse method such as the line spread function or edg e response function because of aliasing from undersampling of the digi tal system. The system modulation transfer function was difficult to r ecover at the spatial frequencies smaller than the Nyquist frequency. The modulation transfer function beyond the Nyquist frequencies was im possible to recover in this study.