Apparatus for examining a body by means of penetrating radiation

Claim 1

Apparatus for examining a body by means of radiation, such as X- or gamma radiation comprising a. a main structural frame, b. a rotary member defining a central aperture positioned on said main structural frame and being arranged to rotate relative thereto, c. a body supporting structure for positioning a body to be examined in said central aperture, said body supporting structure being located and arranged to remain stationary relative to said rotary member, d. a known medium located in proximity with the body supporting structure, e. a source of penetrating radiation and a detector for receiving a beam of penetrating radiation from said source and producing output signals responsive thereto mounted on said rotary member and located on opposite sides of said body supporting structure, f. said source, said detector, and said body supporting structure being spatially arranged such that when a body to be examined is supported by said body supporting structure, it is interposed between the source and said detector, g. an interconnection for said source and said detector to interrelate their positions on opposite sides of said body supporting structure, and to enable them to execute common lateral scanning movements relative to said rotary member, h. motor means for driving said rotary member relative to said main structural frame to produce orbital scanning about the axis of said rotary member, and for driving said source and said detector to execute repetitive common lateral scanning movement such that for each lateral scan the beam of radiation is carried into a region beyond that region to be occupied by a body when supported by said supporting structure, i. said lateral and orbital scanning being correlated for providing alternate predetermined increments of orbital and lateral scanning, j. said known medium being positioned to intercept said beam in said first mentioned region to cause said detector to produce an output signal related to the attenuation of said known medium and independent of the attenuation of the body undergoing examination, and k. a circuit for combining the last mentioned detector output signals with detector output signals related to the attenuation of the body undergoing examination to reference the latter signals.