Three-dimensional contents determination method using transmitted x-ray

Abstract

An X-ray that has passed through a target objectis detected by a two-dimensional X-ray detectorcapable of energy discrimination, to determine an actual X-ray strength at a specific energy level. The target objectis rotationally scanned in predetermined angular steps around an axis perpendicular to the X-ray. The target objectis imaginarily divided into a large number of micro-sized unitary cubic cells, and each detection elementis considered to be receiving an X-ray that has passed through a plurality of unitary cubic cells. A data processorcreates a system of equations including a measured intensity ratio between the transmitted and direct X-rays and a theoretical X-ray intensity ratio calculated from the mass absorption coefficients, unknown weight ratios and density of the elements contained in each unitary cubic cell. The number of equations is equal to or larger than the total number of the elements having unknown weight ratios and the density. In this manner, one can measure the three-dimensional distribution of the weight ratio of each element and/or compound and the density in the target object containing a plurality of known kinds of elements and/or compounds.