A digital x-ray imaging system was designed for small-animal studies. This system is a fiber-optics taper-coupled imaging system with two CCD arrays uniquely jointed. The x-ray source of the system has a small focal spot of 20 μm. This digital imaging system contains specially designed shelves to provide magnification levels, ranging from 1.5× to 5×. The system is characterized in terms of its properties of spatial resolution. An observer-based spatial resolution measurement was conducted with a line-pair target and a sector test pattern. The modulation transfer function of the system, with different magnifications, was studied by use of a 10-μm lead slit. The average resolutions at 50% and 5% modulations at 1× magnification were measured as 3.9 and 8.4 lp/mm, respectively, where lp indicates line pairs. With 5× magnification, the 50% and the 5% modulations provided 13.2- and 29.9-lp/mm, respectively, average spatial resolutions. The measurements showed consistency between the two individual CCD arrays; the difference in resolution between the two CCDs is less than 1%, even at high magnifications.
© 2002 Optical Society of America
(040.0040) Detectors : Detectors
(110.4100) Imaging systems : Modulation transfer function
(110.7440) Imaging systems : X-ray imaging
(330.6130) Vision, color, and visual optics : Spatial resolution
Fabrice Ouandji, Eric Potter, Wei R. Chen, Yuhua Li, David Tang, and Hong Liu, "Characterization of a CCD-Based Digital X-Ray Imaging System for Small-Animal Studies: Properties of Spatial Resolution," Appl. Opt. 41, 2420-2427 (2002)