X-ray scatter image reconstruction by balancing of discrepancies between detector responses, and apparatus therefor

A method for imaging object using radiation selected from x-rays, gamma rays and fast neutrons;

• a source of said radiation, a radiation detector having a sight axis extending through said object and a forward-inverse numerical analysis algorithm;
• comprising the steps of;
• irradiating said object with a first beam of radiation extending along a first angle relative to said sight axis, and intersecting said sight axis along a first scattering segment;
• using said radiation detector, obtaining a first detector measurement of scattering radiation caused by said first beam;
• irradiating said object with a second beam of radiation extending along a second angle relative to said sight axis and intersecting said sight axis along said first scattering segment, said second angle being different from said first angle;
• using said radiation detector, obtaining a second detector measurement of scattering radiation caused by said second beam;
• formulating a first ratio with said first and second detector measurements;
• calculating first and second calculated detector responses;
• making a second ratio with said calculated detector responses;
• iteratively balancing relative errors between said first and second ratios and calculating corrected radiation attenuation coefficients of said object alone said first and second beams and said segment;
• and
• relating said corrected radiation attenuation coefficients to visual indicators and constructing an attenuation-coefficient image of said object along said first and second beams and said segment.

A method for imaging an object using radiation selected from x-rays or gamma rays, comprising the steps of:

• a) providing a collimated radiation detector pointing at said object;
• said collimated detector having a sight axis extending through said object;
• b) providing means for irradiating said object with one or more radiation beams having a shape selected from a pencil beam, a fan beam or a cone beam;
• c) irradiating said object with a first radiation beam having a first beam path intersecting said sight axis of said detector along a first segment of said sight axis;
• said first segment being selected so that said detector detects a non-zero measurement;
• d) using said detector, obtaining a first actual detector measurement of radiation scattered by said object from said first radiation beam;
• e) irradiating said object with a second radiation beam having a second beam path different from said first beam path;
• said second beam path intersecting said sight axis of said detector along said first segment of said sight axis;
• f) using said detector, obtaining a second actual detector measurement of radiation scattered by said object from said second radiation beam;
• g) associating said first and second actual detector measurements with said first and second beam paths respectively;
• h) moving said object relative to said detector, or moving said beam paths relative to said sight axis of said detector or relative to each other such that an intersection thereof with said sight axis is a second common segment different from said first segment;
• i) repeating said steps of irradiating, obtaining, associating and moving, and obtaining first and second actual detector measurements for each of a second and subsequent pairs of actual detector measurements of radiation scattered by said object corresponding respectively to first and second beam paths in each of a second and subsequent pairs of beam paths, until all voxels in said object have been intersected at least twice by said beam paths;
• while obtaining each of said pairs of actual detector measurements;
• defining first and second guessed radiation attenuation coefficients through said object along a corresponding pair of beam paths;
• using said first and second guessed radiation attenuation coefficients, calculating first and second estimated detector measurements corresponding to said guessed radiation attenuation coefficients along said corresponding pair of beam paths;
• comparing a first ratio of said first and second estimated detector measurements with a second ratio of said pair of actual detector measurements for said corresponding pair of beam paths or, comparing a first ratio of said first estimated detector measurement and said first actual detector measurement for said first beam path in said corresponding pair of beam paths with a second ratio of said second estimated detector measurement and said second actual detector measurement for said second beam path in said corresponding pair of beam paths, and obtaining a difference between said first and second ratios;
• using said difference, correcting said first and second guessed radiation attenuation coefficients,
• repeating said steps of calculating, comparing and correcting, and obtaining first and second corrected radiation attenuation coefficients along said first and second beam paths in said corresponding pair of beam paths respectively;
• and
• j) using matrix manipulation and image reconstruction algorithms, relating said corrected radiation attenuation coefficients to density values and constructing a density image of said object, or relating said corrected radiation attenuation coefficients to visual indicators and constructing an attenuation-coefficient image of said object.

An apparatus for measuring radiation attenuation coefficients of material inside an object, comprising:

• a first collimated detector having a first sight axis;
• a first radiation source having a first beam axis, said first beam axis and said first sight axis extending along a same plane;
• a second radiation source having a second beam axis, said second beam axis also extending along said same plane and said first and second radiation sources and said first collimated detector being on a same side of said object;
• said beam axes being non-parallel with each other and being aligned to intersect said first sight axis along a same segment of said first sight axis.