Abstract: In a computed tomography X-ray system, the number of A/D converters required to digitize detector output signals is reduced without degrading the resultant tomographic image. This hardware reduction results from combining certain detector output signals into a pseudo detector having a single output. The detector output signals thus combined represent data corresponding to X-ray beams having substantially the same Radon radius. Preferably such X-ray beams also traverse substantially the same region of the CT system's reconstruction circle. Where the pseudo detector includes the output signals read from N sequentially scanned detectors D.sub.i, where i=1 denotes the first read detector and i=N the last read detector, the output of each detector D.sub.i is delayed a time (N-i).tau., and the thus delayed outputs are summed together to provide the pseudo detector output. In the above relationship, .tau. is the interval between reading adjacent detectors D.sub.i and D.sub.i+1.

Abstract: A scanning electron beam computed tomography scanner is disclosed herein and includes means defining a vacuum chamber, means for producing an electron beam at one location in the chamber and for directing it to a second location therein, a target located at a third position therein of the type which produces X-rays as a result of the impingement thereon by the electron beam, means for focusing the beam onto the target in the form of a beam spot and for scanning the beam spot across the target along a particular scan path in order to produce X-rays, and means for monitoring the profile, position, and orientation of the beam spot at a plurality of locations along the scan path. The specific scanner disclosed also includes an arrangement for determining from the signals produced by the monitoring devices if the beam spot conforms to as desired profile, position, and orientation and automatically adjusting the electron beam such that its profile, position, and orientation conform to desired values.

Abstract: An imaging system generates images of the interior of an object using radiation which is attenuated and scattered by the interior of the object. The object is radiated at a number of points near the exterior of the object, and the radiation emerging from the object is measured at an array of exit points near the exterior of the object. The interior of the object is modelled as an array of volume elements called voxels. Each voxel is modelled as having scattering and attenuation properties, represented by numerical coefficients. The system computes the intensity of radiation that would emerge from the object at the exit points if the interior of the object were characterized by a currently assigned set of values for the scattering and attenuation coefficients. Then, the differences between the measured intensities and the computer intensities are used to compute an error function relates to the magnitude of the errors in the reconstruction.

Abstract: A scanning beam computed tomography scanner is disclosed herein and includes means defining a vacuum chamber, means for producing an electron beam at one location in the chamber and for directing it to a second location therein, a target of the type which produces X-rays as a result of the impingement thereon by the electron beam, and means for focusing the beam onto the target in the form of a beam spot and for scanning the beam spot across the target along a particular scan path in order to produce X-rays. The specific scanner disclosed also includes an arrangement for monitoring the profile, position and orientation of the beam spot at a plurality of different points along the scan path.

Abstract: A scanning electron beam computed tomography scanner is disclosed herein and includes means defining a vacuum chamber, means for producing an electron beam at a first location in the chamber and for directing the beam to a second location therein along a particular desired path. A target of a type which produces X-rays as a result of the impingement thereon by the electron beam is positioned at a third location and means at the second location are provided to cause the beam to impinge on the target in a scanning fashion for producing X-rays. The scanner also includes a system for maintaining the electron beam on the desired path between the first and second locations. To this end, the system includes first means acting on the beam between these locations so as to detect for deviations, if any, between the actual path taken by the beam and the desired path and means responsive to these deviations, again if any, for adjusting the position of the electron beam in order to eliminate the deviations.