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Title: Apparatus for examining bodies by means of penetrating radiation
Claims: What I claim is: 1. Medical radiographic apparatus for investigating a substantially planar region of the body of a patient for the purpose of evaluating the absorption coefficient, with respect to penetrating radiation, at a plurality of elemental locations distributed over said region, the apparatus comprising a rotatable support member having an aperture adapted to receive the part of said body in which said region is located, a motor for causing said support member to rotate about an axis which intersects said region and passes through said aperture, a source of said penetrating radiation, said source being supported by said member and being disposed to project said radiation through said aperture with said radiation fanning out from said source and in alignment with said region, a bank of radiation-sensitive detectors supported by said support member and disposed to intercept radiation which has traversed said aperture; said detectors being positioned to intercept radiation projected along respective beams of said radiation and arranged to provide output signals indicative of the amount of radiation transmitted along the paths, through the aperture, followed by said beams, the beams diverging as they proceed away from the source, lateral scanning means for moving said source laterally in alignment with said region so as to scan said radiation laterally across said region; the lateral movement of the source being emulated by the bank of detectors so that, during each lateral scanning motion, each detector provides a group of output signals indicative of the amount of radiation transmitted through said aperture along a respective set of substantially parallel beam paths; the sets being orientated with respect to each other in accordance with the angular separation of the beams, the motor and the lateral scanning means being operatively connected to produce a plurality of lateral scans in which said diverging beams are rotated as a whole by an angle corresponding to the number of beams and their angular separation. 2. Apparatus as claimed in claim 1 wherein said circuits for processing include a matrix store having a storage location for each of said elemental locations of said region, and means for distributing to each storage location signals representative of output signals relating to beam paths which intersect the corresponding elemental location and also contributions derived from output signals relating to beam paths which do not intersect said corresponding elemental location, said representative signals and said contributions being combined to evaluate the respective absorption coefficient for said corresponding elemental location with higher accuracy that would be possible if said contributions were not utilized. 3. Apparatus as claimed in claim 1 wherein said motor is adapted to rotate said rotatable support member in steps, each step being through said predetermined angle. 4. Apparatus according to claim 1 wherein said motor and said lateral scanning means include means for producing lateral scans interleaving said first-mentioned plurality of lateral scans, in which said detectors and diverging beams are displaced to cause said detectors to provide groups of output signals indicative of the amount of radiation transmitted through said aperture along respective further sets of substantially parallel beam paths interleaved in angle with the sets of substantially parallel beam paths corresponding to the first-mentioned lateral scans. 5. Radiographic apparatus including a source of a fan-shaped, substantially planar spread of penetrating radiation, means defining a patient position, supporting means supporting said source so that said radiation projects through a selected region of said patient position, detector means including a plurality of detector devices, supported by said supporting means, to respectively receive radiation projected through said region along different beams in said spread, said beams diverging from one another in travelling from said source to said detectors, lateral scanning means causing said source and said detecting means to execute a succession of lateral scanning movements relative to said patient position, rotational scanning means causing said source and said detector means to rotate around said patient position about an axis intersecting said region, and means causing said detector means to shift laterally relative to said source between successive lateral scanning movements. Other info: Inventors: Hounsfield, Godfrey Newbold (Winthorpe, GB) Application Number: 651813 Filing Date: 1976-01-23 Publication_date: 1978-07-25 Assignee: EMI Limited (Hayes, GB) Primary Class(es): 378/14 Other Classes: US Patent Ref:
Other Refs:
Primary Examiner: Willis, Davis L. Assistant Examiner: Attorney: Cooper, Dunham, Clark, Griffin & Moran |
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