Abstract: Disclosed is a collimator for a tomographic scanner which performs the collimator function of dividing a fan of radiation into a multiplicity of finger beams and the attenuator function of causing a generally bell-shaped radiation energy distribution across a scan circle. The collimator has larger effective apertures for forming radiation into finger beams to traverse the center of the scan circle than for forming finger beams to traverse the edges of the scan circle. The width of the collimator apertures are defined by radially oriented vanes arranged along a circular arc. By offsetting the radiation source from the geometric center of the circular arc, the vanes defining the width of some apertures are more skewed than others relative to the radiation paths.

Abstract: The method of determining collimator aperture efficiency for a computerized tomographic scanner having a plurality of radiation detectors positioned along a detector arc, a source of radiation having a focal spot having radiation flux distribution positioned across a scan circle from at least part of the detector arc, and a collimator having a plurality of apertures arranged in a collimator arc around said source.Also disclosed is a tomographic scanner having a circular detector arc, a radiation source moveable along a circular arc and an arcuate collimator having apertures in which the width of the collimator aperture in the geometry of the system has high efficiency. The ratio of the detector radius to the source radius, to the collimator radius, to the aperture width is 36:24.3;9.4:0.024.

Abstract: In a CT scanner having a rotating source of radiation and a series of stationary radiation detectors spaced about the axis of rotation of the source, an eclipsing shutter mechanism restricts the width of the diverging fan pattern of radiation to that portion of the patient scan circle which is intermediate the array of stationary detectors and the orbiting source. The eclipsing shutter may include a single elongated slit aperture for flooding the scan circle with radiation or a plurality of smaller apertures defining a collimator for continuously training each one of a plurality of discrete diverging beams in the fan pattern on a single stationary detector during rotation of the source for as long as the separate beam intersects the scan circle. An epicyclic gear train powered by the rotation of the source drives the shutter mechanism in a counter-rotation and causes the collimator to keep each beam aimed at a respective detector.