METHODS AND APPARATUS FOR DETERMINING INFORMATION REGARDING CHEMICAL COMPOSITION USING X-RAY RADIATION

1 . A method comprising:

generating first monochromatic x-ray radiation at a first energy;

directing at least some of the first monochromatic x-ray radiation to irradiate subject matter of interest;

detecting at least some of the first monochromatic x-ray radiation transmitted through the subject matter of interest; and

determining information about a chemical composition of the subject matter of interest based, at least in part, on the detected first monochromatic x-ray radiation and the first energy.

2 . The method of claim 1 , wherein determining information about the chemical composition of the subject matter of interest includes computing a first mass absorption coefficient value of the subject matter of interest based, at least in part, on the detected first monochromatic x-ray radiation.

3 . The method of claim 2 , wherein determining information about the chemical composition of the subject matter of interest includes using the computed first mass absorption coefficient value of the subject matter of interest and the first energy to determine that material is present in the subject matter of interest.

4 . The method of claim 3 , wherein determining information about the chemical composition of the subject matter of interest includes identifying one of a plurality of characteristic curves based, at least in part, on the computed first mass absorption coefficient value of the subject matter of interest and the first energy.

5 . The method of claim 4 , wherein each of the plurality of characteristic curves represents mass absorption coefficient values as a function of energy for a respective material, and wherein identifying one of the plurality of characteristic curves includes identifying which of the plurality of characteristic curves best matches the computed first mass absorption coefficient value at the first energy.

6 . The method of claim 1 , further comprising:

generating second monochromatic x-ray radiation at a second energy;

directing at least some of the second monochromatic x-ray radiation to irradiate the subject matter of interest;

detecting at least some of the second monochromatic x-ray radiation transmitted through the subject matter of interest; and

determining information about the chemical composition of the subject matter of interest based, at least in part, on the detected second monochromatic x-ray radiation and the second energy.

7 . The method of claim 6 , wherein determining information about the chemical composition of the subject matter of interest comprises:

computing a first mass absorption coefficient value of the subject matter of interest based, at least in part, on the detected first monochromatic x-ray radiation; and

computing a second mass absorption coefficient value of the subject matter of interest based, at least in part, on the detected second monochromatic x-ray radiation;

8 . The method of claim 7 , wherein determining information about the chemical composition of the subject matter of interest includes using the computed first mass absorption coefficient value and the first energy, and the computed second mass absorption coefficient value and the second energy to determine that material is present in the subject matter of interest.

9 . The method of claim 8 , wherein determining information about the chemical composition of the subject matter of interest includes identifying one of a plurality of characteristic curves based, at least in part, on the computed first mass absorption coefficient value and the first energy, and the computed second mass absorption coefficient value and the second energy.

10 . The method of claim 9 , wherein each of the plurality of characteristic curves represents mass absorption coefficient values as a function of energy for a respective material, and wherein identifying one of the plurality of characteristic curves includes identifying which of the plurality of characteristic curves best matches the computed first mass absorption coefficient value at the first energy and the computed second mass absorption coefficient value at the second energy.

11 . The method of claim 1 , wherein generating the first monochromatic x-ray radiation comprises:

generating broad spectrum x-ray radiation from an x-ray tube comprising a first target that, in response to being irradiated by electrons, emits the broad spectrum x-ray radiation; and

directing at least some of the broad spectrum x-ray radiation to irradiate a second target comprising material that, in response to the irradiation, emits the first monochromatic x-ray radiation.

12 . The method of claim 6 , wherein generating the first monochromatic x-ray radiation and the second monochromatic x-ray radiation comprises:

generating broad spectrum x-ray radiation from an x-ray tube comprising a first target that, in response to being irradiated by electrons, emits the broad spectrum x-ray radiation;

directing at least some of the broad spectrum x-ray radiation to irradiate a second target comprising material that, in response to the irradiation, emits the first monochromatic x-ray radiation; and

directing at least some of the broad spectrum x-ray radiation to irradiate a third target comprising material that, in response to the irradiation, emits the second monochromatic x-ray radiation.

13 . A system comprising:

a monochromatic x-ray radiation source configured to generate first monochromatic x-ray radiation at a first energy and to direct at least some of the first monochromatic x-ray radiation to irradiate subject matter of interest;

a detector array arranged to detect at least some of the first monochromatic x-ray radiation transmitted through the subject matter of interest; and

at least one processor programmed to determine information about a chemical composition of the subject matter of interest based, at least in part, on the detected first monochromatic x-ray radiation and the first energy.

14 . The system of claim 13 , wherein the at least one processor is programmed to compute a first mass absorption coefficient value of the subject matter of interest based, at least in part, on the detected first monochromatic x-ray radiation.

15 . The system of claim 14 , wherein the at least one processor is programmed to use the computed first mass absorption coefficient value of the subject matter of interest and the first energy to determine that material is present in the subject matter of interest.

16 . The system of claim 15 , wherein the at least one processor is programmed to identify one of a plurality of characteristic curves based, at least in part, on the computed first mass absorption coefficient value of the subject matter of interest and the first energy.

17 . The system of claim 16 , wherein each of the plurality of characteristic curves represents mass absorption coefficient values as a function of energy for a respective material, and wherein at least one processor is programmed to identify which of the plurality of characteristic curves best matches the computed first mass absorption coefficient value at the first energy.

18 . The system of claim 13 , wherein the monochromatic x-ray source is configured to generate second monochromatic x-ray radiation at a second energy and direct at least some of the second monochromatic x-ray radiation to irradiate the subject matter of interest, wherein the detector array is configured to detect at least some of the second monochromatic x-ray radiation transmitted through the subject matter of interest, and wherein the at least one processor is configured to determine information about the chemical composition of the subject matter of interest based, at least in part, on the detected second monochromatic x-ray radiation and the second energy.

19 . The system of claim 18 , wherein at least one processor is programmed to:

compute a first mass absorption coefficient value of the subject matter of interest based, at least in part, on the detected first monochromatic x-ray radiation; and

compute a second mass absorption coefficient value of the subject matter of interest based, at least in part, on the detected second monochromatic x-ray radiation.

20 . The system of claim 19 , wherein the at least one processor is programmed to use the computed first mass absorption coefficient value and the first energy, and the computed second mass absorption coefficient value and the second energy to determine that material is present in the subject matter of interest.

21 . The system of claim 20 , wherein the at least one processor is programmed to identify one of a plurality of characteristic curves based, at least in part, on the computed first mass absorption coefficient value and the first energy, and the computed second mass absorption coefficient value and the second energy.

22 . The system of claim 21 , wherein each of the plurality of characteristic curves represents mass absorption coefficient values as a function of energy for a respective material, and wherein the at least one processor is programmed to identify which of the plurality of characteristic curves best matches the computed first mass absorption coefficient value at the first energy and the computed second mass absorption coefficient value at the second energy.

23 . The system of claim 13 , wherein monochromatic x-ray radiation source is configured to:

generate broad spectrum x-ray radiation from an x-ray tube comprising a first target that, in response to being irradiated by electrons, emits the broad spectrum x-ray radiation; and

direct at least some of the broad spectrum x-ray radiation to irradiate a second target comprising material that, in response to the irradiation, emits the first monochromatic x-ray radiation.

24 . The system of claim 18 , wherein monochromatic x-ray radiation source is configured to:

generate broad spectrum x-ray radiation from an x-ray tube comprising a first target that, in response to being irradiated by electrons, emits the broad spectrum x-ray radiation;

direct at least some of the broad spectrum x-ray radiation to irradiate a second target comprising material that, in response to the irradiation, emits the first monochromatic x-ray radiation; and

direct at least some of the broad spectrum x-ray radiation to irradiate a third target comprising material that, in response to the irradiation, emits the second monochromatic x-ray radiation.