Multi-parameter X-ray computed tomography
View Patent ↗The present invention relates to the field of x-ray imaging. More particularly, embodiments of the invention relate to methods, systems, and apparatus for imaging, which can be used in a wide range of applications, including medical imaging, security screening, and industrial non-destructive testing to name a few. Specifically provided as embodiments of the invention are systems for x-ray imaging comprising: a) a first collimator-and-detector assembly having a first operable configuration to provide at least one first dataset comprising primary x-ray signals as a majority component of its data capable of being presented as a first image of an object subjected to x-ray imaging; b) a second collimator-and-detector assembly having a second operable configuration or wherein the first collimator-and-detector assembly is adjustable to a second configuration to provide at least one second dataset comprising primary and dark-field x-ray signals as a majority component of its data capable of being presented as a second image of the object; and c) a computer operably coupled with the collimator-and-detector assemblies comprising a computer readable medium embedded with processing means for combining the first dataset and the second dataset to extract the dark-field x-ray signals and produce a target image having higher contrast quality than the images based on the first or second dataset alone. Such systems can be configured to comprise at least two collimator-and-detector assemblies or configurations differing with respect to collimator height, collimator aperture, imaging geometry, or distance between an object subjected to the imaging and the collimator-and-detector assembly.
1. A method for producing an x-ray image comprising:
providing at least one first dataset of primary x-ray signals as a majority of its data capable of being presented as a first image of an object subjected to x-ray imaging;
providing at least one second dataset comprising dark-field x-ray signals and primary x-ray signals as a majority of its data capable of being presented as a second image of the object;
combining the first dataset and the second dataset using a computer comprising a computer readable medium embedded with processing means for obtaining a target dataset having more dark-field (small-angle scattering) x-ray signals than the first or second dataset alone for producing a target image of the object which has higher contrast quality than the images based on the first or second dataset alone.
2. The method of claim 1 comprising providing the first and second datasets using collimator-and-detector assemblies or configurations that differ with respect to collimator height, collimator aperture, imaging geometry, or distance between an object subjected to the imaging and the collimator-and-detector assembly.
3. The method of claim 1 , wherein the computer readable medium embedded with processing means is based on:
a) Radon transform data with respect to a small-angle scattering coefficient distribution derived from the principle of photon energy conservation:
ln
[
1
+
T
s
(
r
+
R
θ
)
T
a
(
r
+
R
θ
)
]
=
∫
0
R
μ
s
(
r
+
s
θ
)
ⅆ
s
(
9.1
)
where
T
a
(
r
+
R
θ
)
=
Φ
a
(
r
+
R
θ
)
Φ
0
and
T
s
(
r
+
R
θ
)
=
Φ
s
(
r
+
R
θ
)
Φ
0
are photon transmission and small-angle scattering transference relative to intensity of incident x-ray Φ 0 respectively; Φ a (r 0 +Rθ) is intensity of transmission photons, and Φ s (r 0 +Rθ) is intensity of small-angle scattering photons, each of which is measured on a detector at distance R along projection angle θ from x-ray source position r 0 ; μ s is the small-angle scattering coefficient; and r is a position after an object; or
b) another governing equation derived from the radiative transfer equation (RTE); or
c) another approximation to the radiative transfer equation (RTE).
4. The method of claim 3 further comprising a computer readable medium embedded with processing means for performing x-ray dark-field tomography (XDT) from the extracted dark-field x-ray data.
5. The method of claim 3 , wherein the target image based on the extracted dark-field x-ray data is produced in a radiographic/2D mode.
6. The method of claim 3 , wherein the target image based on the extracted dark-field x-ray data is produced in a tomographic or stereographical or tomosynthesis mode.
7. The method of claim 3 further comprising performing x-ray dark-field tomography (XDT) from the extracted dark-field data to characterize small-angle scattering properties in terms of one or more parameters, or to characterize small-angle scattering properties in terms of Rayleigh scattering coefficient, or to characterize Rayleigh scattering phase function.
8. A system for x-ray imaging comprising:
a first collimator-and-detector assembly having a first operable configuration to provide at least one first dataset comprising primary x-ray signals as a majority of its data capable of being presented as a first image of an object subjected to x-ray imaging;
a second collimator-and-detector assembly having a second operable configuration or wherein the first collimator-and-detector assembly is adjustable to a second configuration to provide at least one second dataset comprising primary and dark-field x-ray signals as a majority of its data capable of being presented as a second image of the object;
a computer operably coupled with the collimator-and-detector assemblies comprising a computer readable medium embedded with processing means for combining the first dataset and the second dataset to extract the dark-field x-ray signals and produce a target image having higher contrast quality than the images based on the first or second dataset alone.
9. The system of claim 8 , wherein at least two of the collimator-and-detector assemblies or configurations differ with respect to collimator height, collimator aperture, imaging geometry, or distance between an object subjected to the imaging and the collimator-and-detector assembly.
10. The system of claim 8 , wherein the computer readable medium embedded with processing means is based on:
a) Radon transform data with respect to a small-angle scattering coefficient distribution derived from the principle of photon energy conservation:
ln
[
1
+
T
s
(
r
+
R
θ
)
T
a
(
r
+
R
θ
)
]
=
∫
0
R
μ
s
(
r
+
s
θ
)
ⅆ
s
(
9.1
)
where
T
a
(
r
+
R
θ
)
=
Φ
a
(
r
+
R
θ
)
Φ
0
and
T
s
(
r
+
R
θ
)
=
Φ
s
(
r
+
R
θ
)
Φ
0
are photon transmission and small-angle scattering transference relative to intensity of incident x-ray Φ 0 , respectively; Φ a (r 0 +Rθ) is intensity of transmission photons, and Φ s (r 0 +Rθ) is intensity of small-angle scattering photons, each of which is measured on a detector located at distance R along projection angle e from x-ray source position r 0 ; μ s is the small-angle scattering coefficient; and r is a position after an object; or
b) another governing equation derived from the radiative transfer equation (RTE); or
c) another approximation to the radiative transfer equation (RTE).
11. The system of claim 10 further comprising a computer readable medium embedded with processing means for performing x-ray dark-field tomography (XDT) from the extracted dark-field x-ray data.
12. A method of x-ray imaging comprising:
collecting x-ray data with a collimator-and-detector assembly configured to provide at least one first dataset comprising primary x-ray signals as a majority of its data;
adjusting the collimator-and-detector assembly to a second configuration for collecting at least one second dataset comprising primary and dark-field x-ray signals as a majority of its data or collecting the second dataset with a second collimator-and-detector assembly configuration;
computing the first and second datasets with a computer operably coupled with the collimator-and-detector assembly and comprising a computer readable medium embedded with processing means for extracting the dark-field x-ray signals for producing a target image having a higher contrast quality than an image based on the first or second dataset alone.
13. The method of claim 12 further comprising collecting x-ray data with additional collimator-and-detector assemblies or additional collimator-and-detector adjustments and computing two or more of the datasets to extract the dark-field signals for producing an image.
14. The method of claim 12 , wherein at least two of the collimator-and-detector assemblies or adjustments differ with respect to collimator height, collimator aperture, imaging geometry, or distance between an object subjected to the imaging and the collimator-and-detector assembly.
15. The method of claim 12 , wherein the collecting data comprises detecting x-ray photons in a spectrally resolving fashion, or at least one collimator-and-detector assembly or adjustment is configured to detect Compton scattering photons in a spectrally resolving fashion.
16. The method according to claim 15 further comprising performing x-ray dark-field tomography (XDT) and Compton scattering imaging from the extracted spectral x-ray data.
17. The method of claim 12 , wherein at least one collimator-and-detector assembly or adjustment is configured to allow fan-beam or cone-beam scanning along a general trajectory.
18. The method of claim 17 , wherein the trajectory is circular or spiral loci.
19. The method of claim 12 , wherein the computer readable medium embedded with processing means is based on:
a) Radon transform data with respect to a small-angle scattering coefficient distribution derived from the principle of photon energy conservation:
ln
[
1
+
T
s
(
r
+
R
θ
)
T
a
(
r
+
R
θ
)
]
=
∫
0
R
μ
s
(
r
+
s
θ
)
ⅆ
s
(
9.1
)
where
T
a
(
r
+
R
θ
)
=
Φ
a
(
r
+
R
θ
)
Φ
0
and
T
s
(
r
+
R
θ
)
=
Φ
s
(
r
+
R
θ
)
Φ
0
are photon transmission and small-angle scattering transference relative to intensity of incident x-ray Φ 0 , respectively; Φ a (r 0 +Rθ) is intensity of transmission photons and Φ s (r 0 +Rθ) is intensity of small-angle scattering photons each of which is measured on a detector located at distance R along projection angle θ from x-ray source position r 0 ; μ s is the small-angle scattering coefficient; and r is a position after an object; or
b) another governing equation derived from the radiative transfer equation (RTE); or
c) another approximation to the radiative transfer equation (RTE).
20. The method of claim 12 , wherein the target image based on the extracted dark-field x-ray data is produced in a radiographic/2D mode.
21. The method of claim 12 , wherein the target image based on the extracted dark-field x-ray data is produced in a tomographic or stereographical or tomosynthesis mode.
22. The method of claim 12 further comprising performing x-ray dark-field tomography (XDT) from the extracted dark-field data to characterize small-angle scattering properties in terms of one or more parameters, or to characterize small-angle scattering properties in terms of Rayleigh scattering coefficient, or to characterize Rayleigh scattering phase function.