Method and apparatus for tomographic examination of an object by penetrating radiation

Apparatus for examining at least part of an object using penetrating radiation, such as X-rays or gamma rays, comprising:

• (a) transmitting means for transmitting a pluarlity of photons of penetrating radiation through the object along a path;
• (b) scintillator means for detecting the penetrating ray photons and converting energy from the penetrating ray photons into light photons, said scintillator means comprising:
• (1) scintillating plastic of a particular geometric configuration having an entry surface through which penetrating ray photons enter said scintillating plastic and lateral surfaces about said entry surface which collimates both the penetrating ray photons and the light photons and which guides the light photons;
• (2) lining means disposed along said lateral walls for absorbing penetrating ray photons entering said scintillating plastic whose paths are at a substantial angular deviation from a path perpendicular to said entry surface and which are not detected prior to the time such photons reach one of said lateral surfaces;
• (3) reflector means disposed between said lining means and said lateral surfaces for increasing the collimating efficiency and guiding efficiency of said scintillator means for light photons;
• and
• (c) photomultiplier means optically coupled to said scintillator means for detecting the light photons and generating a signal representative of the penetrating ray photons detected, wherein a substantial portion of the light photons generated by the detection of penetrating ray photons are collimated and efficiently guided a substantial distance to said photomultiplier means.