A digital radiographic imaging system, based on a time-delay integration (TDI) charge coupled device (CCD), has been developed. The TDI-CCD optical camera has been coupled to a conventional x-ray image intensifier (XRII) to provide improved image quality and quantitative information in clinical applications and in basic research programs.

The TDI-CCD camera consists of a 512 X 96 element detector, mounted on a computer-controlled translation stage. The detector scans over the optical output of the XRII, in synchrony with a lead collimator which scans an x-ray fan beam across the object of interest. In this manner a 512 X 512 digital radiograph is obtained, in about 4 seconds. Furthermore, if the object is rotated through 360° and many projection images are obtained, a three-dimensional computed-tomographic reconstruction can be obtained. Finally, if the TDI-CCD camera is held stationary and the object is rotated quickly, a transaxial reconstruction of a single slice can be obtained in about 4 seconds.

Results of performance evaluations show that the TDI-CCD optical camera has higher resolution (50 mm'1) and greater dynamic range (2100) than existing video cameras. When used to produce projection radiographs of excised arterial tissue (submersed in iodinated contrast agent) the TDI-CCD system provides quantitative thickness measurements with precision as high as ±0.3%. In computed tomography applications the TDI-CCD system can produce volume reconstructions with (0.025 mm)³ volume elements and provide quantitative measurements of attenuation coefficients to within ±0.02 cm"1. The geometric precision in perimeter measurements from transaxial reconstructions is ±0.1 mm. We conclude that the TDI-CCD radiographic system is useful in a variety of research projects, including in vitro analysis of arterial properties and quantitative investigations using small animals, such as rabbits and rats.