Patient cradle for computerized tomography apparatus

Claim 1

Computerized tomography apparatus including a scanner comprising a rotatable x-ray source for projecting a beam of x-radiation in a path transverse to a longitudinal axis on which an examination body may be disposed, x-ray detector means on a side opposite of the axis from the source for rotating coordinately with the source and for intercepting radiation that is attenuated by a body and emerges therefrom, a support and carriage means for supporting a table top on which a body may rest for being translated into and out of said x-ray beam path, and an improved composite table top characterized by permitting said top and any body thereon to be supported solely in cantilever fashion in said beam path, said top comprising: an elongated core comprised of rigid structural foam having low x-ray attenuating properties and having top and bottom surfaces which have different radii of curvature resulting in said core having a nominally crescent-shaped cross section and in said surfaces intersecting to produce relatively sharp and thin longitudinally extending laterally spaced apart edges, a skin bonded to said core and composed of high strength fibers entrained in heat curable resin and having low x-ray attenuating properties, said skin covering said core including said edges and having a thickness that results in minimal increase in the thickness of said edges, means for mounting said composite top to said carriage means to enable a substantial part of the length of said top to extend in cantilever fashion from said carriage means, said x-ray beam being nominally planar and said longitudinal axis being substantially perpendicular to the plane of the beam and said beam being divergent in said plane from said source to said detector means, predetermined angularly separated diverging rays in said beam being tangent to a circular x-ray image reconstruction zone to which said axis is also substantially perpendicular, said lower surface of said table top having a radius of curvature substantially equal to the radius of said circle and said curvature and circle being concentric so that when said table top is in said beam path and said beam is rotated for projecting laterally and from below said lower surface said predetermined rays will be substantially tangent to the circle of which said bottom surface is an arc portion and rays outside of the angle between said predetermined rays which could cause streaks in the image will be outside of the reconstruction circle.