Portable systems for x-ray imaging of objects up to 20-cm in diameter have been developed for field inspection of industrial objects. These systems can be configured with either a linear diode array (45-cm long, 1024-elements, 12- bits/element) or a large-area amorphous-silicon (a-Si) detector (30 X 40-cm2, 2304 X 3200-elements, 12- bits/element). Each detector utilizes gadolinium oxysulfide as the scintillation element. X-rays are emitted from an 80 to 300-kVp constant-potential source with a spot size of approximately 1.6-mm. The object can be rotated and the source and detector translated vertically for collection of 'spiral' fanbeam or 'helical' conebeam computed-tomography (CT) data. For low-density objects, the reconstructed spatial resolution of CT data collected with either detector is about the same and the choice of detector is determined by detector parameters such as dynamic range and integration/readout time. For higher-density objects, which need to be imaged at higher energies and for which there is a higher probability of Compton scatter, the linear diode array produces better contrast images of small voids in a scattering medium. A series of experiments designed to test the performance of each detector with and without a scattering medium will be presented.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.