X-Ray apparatus for determining the absorption distribution in a flat examination zone

Claim 2

In apparatus for determining an X-ray absorption distribution in a planar examination zone which is situated in a body, the body being disposed within a positioning zone which encloses the examination zone, of the type comprising: X-ray source means which function to produce X-rays, diaphragm means which function to form X-rays produced by the source means into a flat fan-shaped beam which passes through the positioning zone in the plane of the examination zone, detector means situated adjacent the positioning zone which function to receive and measure X-rays in the beam which have passed through the positioning zone, positioning means which function to cause the source means to irradiate the positioning zone from a plurality of successive positions around an axis which extends through the examination zone transverse to the plane thereof, and means which function to attenuate X-rays in the beam so that the average flux of the X-rays which pass through the examination zone is greater than the average flux of the X-rays which pass through the positioning zone but which do not pass through the examination zone; the improvement wherein the means which function to attenuate comprise: one or more absorber pieces which intercept X-rays and which define edges which are oriented transverse to the axis and means which function to move the absorber pieces in synchronism with the operation of the positioning means so that at certain of the positions around the axis the absorber pieces completely shield X-rays which pass through the positioning zone but do not pass through the examination zone from reaching the detector means and the absorber pieces only partially shield said portion of the x-ray beam at others of said positions.

Claim 3

The apparatus of claim 1 wherein the absorber pieces are cylindrical and have a cross-section which is non-circular, the axis of each absorber piece being directed parallel to the plane of the examination zone, and wherein the means which function to move the absorbing pieces rotate one or more of them about its axis.

Claim 4

The apparatus of claim 2 wherein the positioning means rotates the X-ray source means and detector means about the axis which is transverse to the examination zone and wherein the means which function to attenuate comprise further absorption pieces which are rigidly attached to the X-ray source means and which partially shield a portion of the radiation beam which does not pass through the examination zone; the portion of radiation not thus shielded by the further absorption pieces being intermittently shielded by the rotating absorber pieces.

Claim 5

In apparatus for determining an X-ray absorption distribution in a planar examination zone which is situated in a body, the body being disposed within a positioning zone which encloses the examination zone, of the type comprising: X-ray source means which function to produce X-rays, diaphragm means which function to form X-rays produced by the source means into a flat fan-shaped beam which passes through the positioning zone in the plane of the examination zone, detector means situated adjacent the positioning zone which function to receive and measure X-rays in the beam which pass through the positioning zone, positioning means which function to cause the source means to irradiate the positioning zone from a plurality of successive positions around an axis which extends through the examination zone transverse to the plane thereof, and means which function to attenuate X-rays in the beam so that the average flux of the X-rays which pass through the examination zone is greater than the average flux of the X-rays which pass through the positioning zone but which do not pass through the examination zone; the improvement wherein the means which function to attenuate comprise one or more absorber pieces which intercept X-rays and which define edges which are oriented transverse to the axis; the X-ray source means comprises: an X-ray tube, including an anode and a cathode for generating an electron beam which is incident on the anode at a location which forms a focus of the X-ray beam and; means for deflecting the electron beam which function to move the focus parallel to the axis in an oscillating manner so that, at certain locations of the focus, the absorber pieces completely shield a portion of the X-ray beam which passes through the positioning zone without passing through the examination zone from the detector means while at other locations of the focus the absorber pieces only partially shield said portion of the X-ray beam from the detector.

Claim 6

In apparatus for determining an X-ray absorption distribution in a planar examination zone which is situated in a body, the body being disposed within a positioning zone which encloses the examination zone, of the type comprising: X-ray source means which function to produce X-rays, diaphragm means which function to form X-rays produced by the source means into a flat fan-shaped beam which passes through the positioning zone in the plane of the examination zone, detector means situated adjacent the positioning zone which function to receive and measure X-rays in the beam which pass through the positioning zone, positioning means which function to cause the source means to irradiate the positioning zone from a plurality of successive positions around an axis which extends through the examination zone transverse to the plane thereof, and means which function to attenuate X-rays in the beam so that the average flux of the X-rays which pass through the examination zone is greater than the average flux of the X-rays which pass through the positioning zone but which do not pass through the examination zone; the improvement wherein the means which function to attenuate comprise one or more absorber pieces which intercept X-rays and which define edges which are oriented transverse to the axis; the X-ray source means comprises: an X-ray tube, including an anode and a cathode for generating an electron beam which is incident on the anode at a location which forms a focus of the X-ray beam and; means for deflecting the electron beam which function to move the focus parallel to the axis in an oscillating manner so that, at certain locations of the focus, the absorber pieces completely shield a portion of the X-ray beam which passes through the positioning zone without passing through the examination zone from the detector means while at other locations of the focus the absorber pieces only partially shield said portion of the X-ray beam from the detector.