Dual energy radiation scanning of objects
AssigneeVarian Medical Systems, Inc.
InventorPaul Bjorkholm
Life of this patent
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Abstract
In one embodiment, a method of examining an object is disclosed comprising scanning an object at first and second radiation energies, detecting radiation at the first and second energies, and calculating a function of the radiation detected at the first and second energies. The function may be calculated for corresponding portions of the object. It is determined whether the object at least potentially comprises high atomic number material having an atomic number greater than a predetermined atomic number based, at least in part, on the function. The function may be a ratio. The function may be compared to a second function, which may be a threshold having a value based, at least in part, on material of the predetermined atomic number. The second function may be the same as the first function.
Claims31
A method of examining an object, comprising:
- scanning at least a portion of an object at first and second radiation energies, wherein the first and second radiation energies are different and the first and second radiation energies are each greater than 1 MeV;
- detecting radiation at the first and second radiation energies, after interaction with the at least a portion of the object;
- calculating a function of the radiation detected at the first and second energies;
- and
- determining whether the object at least potentially comprises any one of all high atomic number materials having an atomic number greater than a predetermined atomic number, based, at least in part, on the function.
A method of examining an object, the method comprising:
- scanning a first plurality of portions of an object with a first radiation beam at a first energy;
- detecting first radiation after interaction of the first radiation beam with the first plurality of portions;
- scanning a second plurality of portions of the object with a second radiation beam at a second energy different than the first energy;
- detecting second radiation after interaction of the second radiation beam with the second plurality of portions;
- calculating ratios between functions of the first radiation and the second radiation, for corresponding first and second portions;
- comparing calculated ratios to a least one threshold based, at least in part, on a predetermined atomic number;
- and
- determining whether the contents of the object at least potentially comprises high atomic number material having an atomic number greater than a predetermined atomic number based, at least in part, on the comparison.
A system for examining an object, comprising:
- means for scanning at least a portion of an object at first and second radiation energies, wherein the first and second radiation energies are different and the first and second radiation energies are each greater than 1 MeV;
- means for detecting radiation at the first and second radiation energies, after interaction with the object;
- means for calculating a function of the radiation detected at the first and second energies;
- and
- means for determining whether the object at least potentially comprises any one of all high atomic number materials having an atomic number greater than a predetermined atomic number, based, at least in part, on the function.
A system for examining an object, the system comprising:
- at least one radiation source to scan at least a portion of an object at first and second radiation energies, wherein the first radiation energy is different than the second radiation energy and the first and second radiation energies are each greater than 1 MeV;
- at least one detector positioned to detect radiation at the first and second radiation energies, after interaction with the object;
- at least one processor coupled to the detector, the at least one processor being programmed to:
- calculate a function of the radiation detected at the first and second energies;
- and
- determine whether the object at least potentially comprises any one of all high atomic number materials having an atomic number greater than a predetermined atomic number based, at least in part, on the function.
A method of examining an object, comprising:
- defining a class of at least potentially unacceptable materials as all materials having atomic numbers greater than a predetermined atomic number;
- scanning at least a portion of an object at first and second radiation energies, wherein the first and second radiation energies are different;
- detecting radiation at the first and second radiation energies, after interaction with the at least a portion of the object;
- calculating at least one function of the radiation detected at the first and second energies;
- comparing the at least one function to a threshold value between at least certain acceptable materials and the class of at least potentially unacceptable materials, the threshold being based, at least in part, on the predetermined atomic number;
- and
- determining whether the object at least potentially comprises unacceptable material, based, at least in part, on the comparison.
A method of examining an object, comprising:
- scanning at least a portion of an object by a first radiation beam having a first energy;
- scanning the at least a portion of the object by a second radiation beam having a second energy different than the first energy;
- detecting radiation at the first and second radiation energies, after interaction with the at least a portion of the object;
- calculating at least one function of the radiation detected at the first and second energies;
- comparing the at least one function to a threshold based, at least in part, on a non-Special Nuclear Material;
- and
- determining whether the object at least potentially comprises Special Nuclear Material based, at least in part, on the comparison.
Dependencies are inferred from the claim text.