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: An improved ion clearing electrode assembly for use in an electron beam production and control assembly which is especially suitable for use in a scanning electron beam computed tomography X-ray scanning system. The assembly uses a vacuum sealed housing chamber which is evacuated of internal gases and in which the electron beam is generated and propagated. Normally residual gas within the chamber interacts with the electrons of the beam to produce positive ions which have the affect of neutralizing the space charge of the electron beam and thereby causing focusing difficulties and destabilization of the beam. The ion collecting electrodes herein are an improvement of those disclosed in the co-pending Rand U.S. patent application Ser. No. 434,252, now U.S. Pat. No. 4,521,900. The electrodes are designed to extract the ions and reduce their neutralizing effect while maintaining a precisely uniform electric field and therefore beam optical aberrations are minimized.

Abstract: An electron gun which can be easily disassembled to replace a defective cathode assembly and which can be easily and quickly reassembled and realigned.

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.

Abstract: A variable width fan beam of radiation is provided in a high speed X-ray transmission system by a plurality of ring collimators with the ring collimators being mounted whereby spacing between ring collimators can be varied. In preferred embodiment an arcuate array of radiation detectors are mounted in an annular housing which functions as one of the ring collimators.

Abstract: A two dimensional radiograph or a continuously rotating two dimensional radiograph of a patient is obtained using a high speed CT scanning system in which fan beams of radiation are generated by sweeping an electron beam along a target. Collimated X-rays emitted by the target are received by an array of detectors after passing through a patient area between the target and the array of detectors. A single detector position, comprising one or more detectors, can be employed to obtain a single two dimensional projection radiograph. Alternatively, a plurality of detector positions can be employed in measuring radiation and obtaining a continuously rotating two dimensional projection radiograph.