Compton scattering tomography
First Claim
1. A method for imaging the density of material in the interior of an object to be inspected, comprising the steps of:
- (a) providing a monoenergetic source of gamma rays;
(b) providing a position- and energy-sensitive detector;
(c) disposing said source at a first source location exterior to one side of said object, and employing said source to irradiate said object with gamma rays;
(d) employing said detector to detect gamma rays having been Compton scattered at one or more detector location(s) disposed exterior to said one side of said object;
(e) measuring the energy of the detected gamma rays, and recording the locations at which the gamma rays were detected;
(f) determining a locus of possible scattering locations of the detected rays responsive to the measured energy of the detected rays and the locations at which the rays were detected;
(g) determining variation in the density of material in the object responsive to summation of the loci of scattering locations determined in said step (f) by filtered back-projection of the data recorded in step (c) as a function of energy and location of detection of the detected gamma rays; and
(h) imaging the variation in density thus determined.
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Abstract
Apparatus and methods for Compton scattering tomography employ a source of monoenergetic gamma rays and a detector capable of detecting the energy of scattered photons and determining the detector location both disposed on one side of an object to be imaged. Based on analysis of the measurement of the energy of the detected photons and the detector locations, a circle of possible scattering locations is determined as to each scattering event. By performance of a number of experiments as a function of detector location and energy, the density of the object can be reconstructed by filtering and back-projecting the data to yield an image responsive to variation in the density of the material of the object to be imaged.
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Citations
10 Claims
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1. A method for imaging the density of material in the interior of an object to be inspected, comprising the steps of:
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(a) providing a monoenergetic source of gamma rays; (b) providing a position- and energy-sensitive detector; (c) disposing said source at a first source location exterior to one side of said object, and employing said source to irradiate said object with gamma rays; (d) employing said detector to detect gamma rays having been Compton scattered at one or more detector location(s) disposed exterior to said one side of said object; (e) measuring the energy of the detected gamma rays, and recording the locations at which the gamma rays were detected; (f) determining a locus of possible scattering locations of the detected rays responsive to the measured energy of the detected rays and the locations at which the rays were detected; (g) determining variation in the density of material in the object responsive to summation of the loci of scattering locations determined in said step (f) by filtered back-projection of the data recorded in step (c) as a function of energy and location of detection of the detected gamma rays; and (h) imaging the variation in density thus determined. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for imaging the density of material in the interior of an object to be inspected, comprising:
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a monoenergetic source of gamma rays disposed at a first source location exterior to one side of said object, to irradiate said object with gamma rays; detector means for detecting gamma rays having been Compton scattered at known detector locations disposed exterior to one side of said object, means for measuring the energy of the detected gamma rays; means for determining a locus of possible scattering locations of each detected ray responsive to its measured energy; means for determining variation in the density of the material of the object responsive to effective summation of the loci of possible scattering locations, wherein said loci of possible scattering locations lie along circular paths of constant energy; and means for imaging the variation in density thus determined, comprising means for filtering and back-projecting the loci of possible scattering locations at image locations corresponding to the circular paths, thus providing visible indication of variation in the density of material in the object. - View Dependent Claims (10)
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Specification