Non-invasive stationary system for three-dimensional imaging of density fields using periodic flux modulation of compton-scattered gammas

A measurement system comprising:

• a modulating unit configured to receive source gamma rays or Compton-scattered gamma rays from within an inspected object irradiated by mono-energetic gamma rays from an external gamma radiation source and to modulate gamma fluxes of said source gamma rays or Compton-scattered gamma rays with a periodic function of time;
• said modulation unit configured to implement an encoding process, wherein said encoding process tags a plurality of solid angle segments of said Compton-scattered or source gamma fluxes individually with different tags;
• and
• said modulation unit comprises nodal windows, wherein each nodal window is configured to impose a different time modulation to encode said gamma fluxes, wherein said encoded Compton-scattered or source gamma fluxes are used in combination with a scattering process defined by a Compton energy-angle relationship to determine a three-dimensional distribution of local Compton-scattered gamma fluxes within said inspected object.

A measurement system comprising:

• a measuring device configured to apply a Compton scattering process to an analysis of gamma rays scattered from an inspected object, wherein the gamma rays are irradiated from an external gamma radiation source;
• wherein scattering points or a plurality of voxels of said Compton-scattered gamma rays having identical energies form an isogonic surface;
• and
• a modulating unit comprising nodal windows, wherein each nodal window imposes a different time modulation for encoding a two-dimensional cross-section of source gamma fluxes or Compton-scattered gamma fluxes.

A three-dimensional density image generating system comprising:

• a modulating unit comprising nodal windows;
• said modulating unit configured to receive source gamma rays or Compton-scattered gamma rays from within an inspected object irradiated by gamma rays from an external gamma radiation source, such that each nodal window imposes a different time modulation to modulate gamma fluxes of said source gamma rays or Compton-scattered gamma rays and configured to encode cross-sectional portions of source gamma fluxes or Compton single-scattered gamma fluxes to locate a first coordinate and a second coordinate of scattering points or voxels within said inspected object;
• a measuring device configured to identify and separate said source gamma fluxes or said Compton single-scattered gamma fluxes originating from a plurality of voxels present in isogonic slices within the inspected object, and configured to provide a determination of a third coordinate of the scattering points within the inspected object;
• wherein said measuring device is configured to determine a spatial distribution of said Compton single-scattered gamma fluxes;
• and
• wherein said Compton single-scattered gamma flux determination includes a multitude of gamma fluxes of said gamma rays arriving from isogonic slices internal to said inspected object, wherein the isogonic slices comprise portions of isogonic shells within said inspected object.

A non-invasive three-dimensional density distribution measuring device comprising:

• an external isotopic source configured to irradiate an inspected object with gamma rays to generate Compton single-scattered gamma photons, wherein said Compton single-scattered gamma photons obey principles of Compton scattering law;
• a modulator comprising nodal windows, wherein each nodal window imposes a different time modulation to encode a periodic time-dependent oscillation distributed over a two-dimensional area of a source gamma flux or a Compton single-scattered gamma flux, whereas the source gamma flux comprises a plurality of source gamma photons and the Compton single-scattered gamma flux comprises a plurality of said Compton single-scattered gamma photons;
• a spectrometer configured to detect energies and intensities of said Compton single-scattered gamma photons;
• and
• a multi-channel pulse-height analyzer configured to sort detected gamma signals according to the energies of the detected gamma photons.

An inspection device comprising:

• an external mono-energetic gamma radiation source configured to irradiate an inspected object with gamma photons;
• a gamma photon detection unit configured to detect Compton-scattered gamma photons emanating from said inspected object;
• a modulation unit configured to encode source gammas, or Compton-scattered gammas emanating from the inspected object, enroute toward the gamma photon detection unit;
• a time-varying modulation unit comprising nodal windows, wherein each nodal window imposes a different time modulation to modulate said source gammas or Compton-scattered gammas with a time-variation character of flux attenuation;
• a gamma signal sorting unit configured to sort counts of said detected Compton-scattered gamma photons into various energy bins;
• a signal splitting unit configured to split detector output signals from each of said energy bins into multiple equal components;
• an electronic function generator unit configured to generate digital signals having time-dependent functions;
• a multiplication unit configured to multiply said digital signals with said detector output signals to form a combined product-function signal;
• an integration unit configured to integrate, over time, said combined product-function signal to yield a plurality of linear algebraic equations;
• an equation-solving unit configured to solve said plurality of linear algebraic equations to produce a determination of local Compton-scattered gamma fluxes at points of interest inside the inspected object;
• and
• a data processing unit configured to perform said determination of said local Compton-scattered gamma fluxes and reconstruct an image of a three-dimensional density distribution within said inspected object.

A method of generating a three-dimensional density image, comprising:

• irradiating an object with an external source of gamma photons;
• observing portions of source gamma fluxes or Compton single-scattered gamma fluxes that pass through corresponding nodal windows in a modulating unit and are encoded by each nodal window imposing a different time modulation on said source gamma fluxes or Compton single-scattered gamma fluxes;
• modulating each portion of said source gamma fluxes or Compton single-scattered gamma fluxes that pass through a nodal window with a different time-varying attenuation function, to generate a system of linear algebraic equations;
• solving said system of linear algebraic equations to generate a result;
• and
• storing said results on a computer readable medium.

A method for imaging comprising the steps of:

• irradiating an inspected object with gamma rays from an external gamma radiation source;
• applying a Compton scattering process to a plurality of gamma rays scattered from within the inspected object;
• defining isogonic surfaces and associated isogonic shells as loci of scattering points associated with Compton-scattered gammas scattered through identical scattering angles;
• using a portion of said isogonic shell within the inspected object to form a locus of said scattering points within the inspected object, from which fluxes of said Compton single-scattered gamma photons having the same energy originate, wherein only the portion of the isogonic shell within the inspected object defines an isogonic slice;
• detecting said gamma photons;
• sorting signals from the detected Compton-scattered gamma photons according to a plurality of energies;
• and
• storing said signals from the detected Compton-scattered gamma photons according to said plurality of energies on a computer readable medium.

A method for generating a three-dimensional image, the method comprising the steps of:

• detecting source gamma rays from an external gamma radiation source or Compton-scattered gamma rays from within an inspected object irradiated by said source gamma rays after modulating gamma fluxes of said source gamma rays or said Compton-scattered gamma rays by passing through nodal windows in a modulating unit, wherein each nodal window imposes a different time modulation on said gamma fluxes;
• identifying and separating said Compton-scattered gamma fluxes originating from a plurality of scattering locations from the inspected object;
• formulating a gamma flux calculation procedure, wherein said gamma flux calculation yields magnitudes of Compton single-scattered gamma fluxes arriving from a plurality of known scattering points or voxels within identified isogonic slices and substantially eliminates or reduces multiple-scattered gamma fluxes arriving from said inspected object and background fluxes;
• and
• storing said magnitudes of said Compton single-scattered gamma fluxes on a computer readable medium.

A method of generating a flux distribution image, comprising the steps of:

• irradiating an object with gamma rays from an external gamma source to generate Compton single-scattered gamma rays, wherein said Compton single-scattered gamma rays obey principles of Compton scattering law;
• encoding source gamma flux or Compton single-scattered gamma flux;
• determining energies and intensity levels of said flux of Compton single-scattered gamma rays;
• and
• sorting said energies and measuring flux intensities of portions of the Compton single-scattered gamma flux that pass through nodal windows of a modulator, wherein each nodal window imposes a different time modulation to produce a three-dimensional representation of the local Compton single-scattered gamma flux distribution.

A method of inspecting comprising the steps of:

• irradiating an object with gamma rays from an external gamma source;
• encoding source gamma fluxes or Compton-scattered gamma fluxes by modulating either said source gamma fluxes or said Compton-scattered gamma fluxes with a time variation character, wherein each nodal window of a modulator imposes a different time modulation on said source gamma fluxes or said Compton-scattered gamma fluxes;
• detecting the Compton single-scattered gamma fluxes of Compton-scattered gamma photons transmitted from said object;
• generating output voltage pulse height signals from a detector, based upon individual energies of said detected Compton-scattered gamma photons;
• sorting of registered counts of the detected Compton single-scattered gamma photons into energy bins of a multi-channel analyzer, according to energies of individual detected Compton single-scattered gamma photons;
• splitting the output voltage pulse height signals from the multi-channel analyzer into a plurality of equal sets;
• generating electronic digital signal functions;
• multiplying components of said output voltage pulse height signals from a detector with said digital signal functions to form combined product-function signals;
• time-integrating said combined product-function signals to generate a value representing a term in a plurality of linear algebraic equations;
• storing said plurality of linear algebraic equations for local Compton single-scattered gamma fluxes on a computer readable medium;
• solving said linear algebraic equations for local Compton single-scattered gamma fluxes;
• and
• reconstructing a mass density field of said object by converting numerical local Compton single-scattered gamma fluxes into local mass densities.

A method of determining density images inside an inspected object, the method comprising the steps of:

• utilizing at least two gamma source energies at the same location, each source energy having a different energy so that a number of gamma source energies is greater than a number of source locations;
• combining the number of source locations and the number of source energies to generate a total number of source configurations;
• multiplying the total number of source configurations by a number of detector locations to indicate a number of independent solvable equation systems and to indicate a maximum number of substances with unknown density distributions having solvable solutions;
• and
• storing said number of independent solvable equation systems on a computer readable medium.