High resolution X-ray collimator/detector system having reduced sensitivity to leakage radiation

Claim 1

A high resolution X-ray collimator/detector system having reduced sensitivity to leakage radiation, said system comprising: a collimator having a plurality of narrow tapered slits to limit and define the widths of X-ray beams passing through said slits, thus defining system resolution; and a multi-element ionization chamber X-ray detector immediately adjacent said collimator such that X-ray beam are incident on corresponding detector elements, the detector elements being wider than the X-ray beams, and said detector comprising: a sealed housing with an X-ray permeable window and containing a medium to convert incident X-rays into charged particles; an array of spaced coplanar collector electrodes within said sealed housing which are held at an electric potential; a plurality of voltage electrode portions within said sealed housing parallel to and spaced from said collector electrodes such that electric fields can be established between said collector electrodes and said voltage electrode portions, an active collection volume of a corresponding detector element being defined generally between each collector electrode and a corresponding voltage electrode portion, with the area of each collector electrode determining the extent of the corresponding active collection volume; and guard electrode portions positioned between and substantially coplanar with said collector electrodes, said guard electrode portions being electrically insulated from and at least as wide as said collector electrodes and held at substantially the same electrical potential as said collector electrodes so as to reduce sensitivity to leakage X-ray radiation not passing through the slits and to minimize electric field distortion.