HIGH EFFICIENCY COMPUTER TOMOGRAPHY

• US 20090324047A1
• Filed: 06/29/2009
• Published: 12/31/2009
• Est. Priority Date: 06/27/2008
• Status: Active Grant

• Current Assignee: Wolfram R. Jarisch
• Original Assignee: Wolfram R. Jarisch
• Inventors: JARISCH, Wolfram R.
• Granted Patent: US 8,660,328 B2
• Time in Patent Office: Days
• US Class Current: 382/131
• CPC Class Codes: G01N 23/00 Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
• CPC Class Codes: G06T 11/006 Inverse problem, transformation from projection-space into object-space, e.g. transform methods, back-projection, algebraic methods
• CPC Class Codes: G06T 2211/424 Iterative

Abstract

A system comprising: one or more transmitters to transmit an excitation energy into an object under observation; one or more detectors to generate projection space data encoding an energy received by the one or more detectors in response to the transmitted excitation energy into the object under observation; a controller to control the one or more transmitters to transmit the excitation energy and the one or more detectors to generate the projection space data; and an image reconstructor to receive the projection space data and to process the projection space data by: computing a first quantity characterizing a difference between the projection space data and predicted projection data; computing a second quantity corresponding to at least one impulse response, each impulse response corresponding to a reference voxel of unit-intensity; computing an update value using the first quantity and an inverted function of the second quantity; and reconstructing an object space image representing the object under observation using the update value.

Claims

1. A system comprising:

one or more transmitters to transmit an excitation energy into an object under observation;

one or more detectors to generate projection space data encoding an energy received by the one or more detectors in response to the transmitted excitation energy into the object under observation;

a controller to control the one or more transmitters to transmit the excitation energy and the one or more detectors to generate the projection space data; and

an image reconstructor to receive the projection space data and to process the projection space data by;

computing a first quantity characterizing a difference between the projection space data and predicted projection data;

computing a second quantity corresponding to at least one impulse response, each impulse response corresponding to a reference voxel of unit-intensity;

computing an update value using the first quantity and an inverted function of the second quantity; and

reconstructing an object space image representing the object under observation using the update value.

2. The system according to claim 1, wherein the excitation energy is at least one of electromagnetic (EM) energy, X-Ray energy, particle beams, infra-red energy, optical energy, or vibration energy.

3. The system according to claim 1, wherein the predicted projection data is computed based on a set of object space voxels, wherein the set of object space voxels covers a plurality of predetermined resolution grids of varying sizes when the set of object space voxels are projected to projection space.

4. The system according to claim 3, wherein computing an update value using the first quantity and an inverse function of the second quantity comprises:

convolving the first quantity with the inverted function of the second quantity.

5. The system according to claim 1, wherein reconstructing the object space image representing the object under observation using the update value comprises:

revising the set of object space voxels with the update value.

6. The system according to claim 1, further comprising:

an output device to receive the object space image representing the object under observation, wherein the output device is at least one of a data storage device, a display device, or a printing device.

7. The system according to claim 1, further comprising:

an investigator computer to receive the object space image and programmed to perform extraction of diagnostic information from the object space image or to fine tune parameters for at least one of the one or more transmitters, the one or more detectors, or the image reconstructor.

8. A workstation comprising:

one or more processors; and

one or more data storage devices storing software to be executed by the one or more processors, the software comprising;

software code to receive input data representing an object projected from an object space to a projection space;

software code to compute a first quantity characterizing a difference between the input data and predicted projection data;

software code to compute a second quantity corresponding to at least one impulse response, each impulse response corresponding to a reference voxel of unit-intensity at a location in the object space;

software code to compute an update value using the first quantity and an inverted function of the second quantity; and

software code to reconstruct an object space image representing the object under observation using the update value.

9. The workstation according to claim 8, wherein the input data is received from at least one of a projection image acquisition system, the one or more data storage devices, another one or more data storage devices, a software simulation executed by the one or more processors, or a software simulation executed by another one or more processors.

10. The workstation according to claim 8, wherein the input data is received via a data bus, a cable, a wired network, or a wireless network.

11. The workstation according to claim 8, further comprising:

an output device to receive the image, wherein the output device is at least one of the one or more data storage devices, another one or more data storage devices, a display device, or a printing device.

12. The workstation according to claim 8, wherein the software further comprises software code to convolve the first quantity with the inverted function of the second quantity.

13. A method implemented by one or more processors executing software code stored on one or more data storage devices, the method comprising:

receiving input data representing an object projected from an object space to a projection space from at least one of a projection image acquisition system, the one or more data storage devices, another one or more data storage devices, a software simulation executed by the one or more processors, or a software simulation executed by another one or more processors;

computing a first quantity characterizing a difference between the input data on a resolution grid and predicted projection data on the resolution grid;

computing a second quantity corresponding to at least one impulse response, each impulse response corresponding to a reference voxel of unit-intensity at a location in the object space;

computing an update value using the first quantity and an inverted function of the second quantity;

reconstructing an image representing the object under observation using the update value, and

outputting the reconstructed image to an output device, wherein the output device is at least one of the one or more data storage devices, another one or more data storage devices, a display device, or a printing device;

wherein receiving the input data, computing the first quantity, computing the second quantity, computing the update value, reconstructing the image, and outputting the reconstructed image are performed by the one or more processors according to the software code stored on the one or more data storage devices.

14. The method according to claim 13, wherein the resolution grid is obtained from a plurality of predetermined resolution grids of varying sizes.

15. The method according to claim 14, wherein the predicted projection data is computed based on a set of object space voxels, the set of object space voxels covers the plurality of predetermined resolution grids of varying sizes when the set of object space voxels are projected to projection space.

16. The method according to claim 15, further comprising:

smoothing with a smoothing kernel at least one of the input data on the resolution grid or the set of object space voxels.

17. The method according to claim 15, wherein the set of object space voxels are constrained within a range of values.

18. The method according to claim 13, wherein the first quantity is characterized as a measure of error between the input data and the predicted projection data.

19. The method according to claim 13, wherein the second quantity includes contributions from a noise variance obtained from measurements of the input data.

20. The method according to claim 13, wherein the inverted function is computed for a surrounding area covering the location of the reference voxel of unit-intensity in the object space.

21. The method according to claim 13, wherein reconstructing the image comprises:

convolving the first quantity with the inverted function of the second quantity to obtain the update value.

22. The method according to claim 13, wherein the update value is further limited by a limiting function.

23. The method according to claim 13, further comprising:

revising the set of object space voxels using the update value.

24. The method according to claim 23, further comprising:

changing to a different resolution grid having a larger size than the resolution grid after the set of object space voxels is revised.

25. The one or more data storage devices of claim 13 to store the software for execution by the one or more processors to perform the method according to claim 13.