Optimization of a CR system comprising line-scanning and needle image plate technology with respect to examinations of extremities

摘要

A CR system based on line-scanning and needle image plate technologies (CsBr), was modified by means of an improved line light source for stimulation and a high aperture line optics for light collection. For comparison, two types of needle image plates were used, i.e. standard and high resolution plates. The image quality performance was investigated in terms of modulation transfer function, detective quantum efficiency and visual impression of both anthropomorphic and technical phantom images, with respect to application for X-ray examinations of extremities. MTF and DQE at beam quality RQA 3 were clearly improved by the modified scanning components. Further improvement especially with respect to MTF at spatial frequencies beyond 2 LP/mm was obtained via the high resolution image plate, but at reduced low frequency DQE values. The visual inspection of images of a high contrast resolution pattern and an anthropomorphic hand phantom revealed a clear preference for the modified system. The use of the high resolution image plate alone resulted in images with higher sharpness but increased noise. The best performance — at constant X-ray exposure dose - was delivered by the combination of improved optics components with the adapted needle image plate.