Methods and apparatus for noise compensation in an imaging system

• US 6,061,419 A
• Filed: 08/25/1998
• Issued: 05/09/2000
• Est. Priority Date: 08/25/1998
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Hsieh, Jiang, Toth, Thomas L.
• Primary Examiner(s): BRUCE, DAVID VERNON
• Application Number:
  US09/139,833
• Time in Patent Office: 623 Days
• Field of Search: 378/4, 378/15, 378/901
• US Class Current: 378/4
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/4085 Cone-beams
• CPC Class Codes: Y10S 378/901 Computer tomography program or processor

Abstract

Methods and apparatus for performing channel dependent and gain dependent smoothing filter (across channels) to compensate for noise in a multislice imaging system are described. The smoothing mainly affects the radial resolution. The filter can be combined with the matrix deconvolution filter typically used in multi-slice scanners. The filter is channel and DAS gain dependent and provides that an image generated from data collected in a multi-slice scan has about the same image quality, e.g., noise reduction, as images generated by other types of scanners.

Claims

1. A method for reconstructing an image in an imaging system, said method comprising the steps of:

performing a scan to obtain data; and

performing channel dependent filtering of data.

2. A method in accordance with claim 1 wherein performing filtering of the data is executed in accordance with:

##EQU3## where H is a resulting composite filter, D is a deconvolution filter, f is a channel and gain dependent smoothing filter, γ

is a channel, g is a gain dependent smoothing filter, and k is a detector row number.

3. A method in accordance with claim 1 wherein performing filtering on the data comprises the step of applying an enhancing filter to the data.

4. A method in accordance with claim 1 wherein performing filtering on the data comprises the step of applying a smoothing filter to the data.

5. A method in accordance with claim 1 wherein filtering the data is performed in accordance with (d, 1-2d, d) where:

space="preserve" listing-type="equation">d=m(1-sin (γ

)/γ

).

6. A method in accordance with claim 1 wherein the imaging system is a single slice system.

7. A method in accordance with claim 1 wherein the imaging system is a multislice system.

8. A method in accordance with claim 1 wherein the imaging system includes a data acquisition system, and the filtering also is data acquisition system gain dependent.

9. An imaging system comprising an x-ray source and at least one detector module, said system further comprising a data acquisition system coupled to said detector, said system configured to:

perform a scan to obtain data; and

perform channel dependent filtering of data.

10. A system in accordance with claim 9 wherein to perform filtering of the data, said system is configured to filter the data in accordance with:

##EQU4## where H is a resulting composite filter, D is a deconvolution filter, f is a channel and gain dependent smoothing filter, γ

is a channel, g is a gain dependent smoothing filter, and k is a detector row number.

11. A system in accordance with claim 9 wherein to perform filtering on the data, said system is configured to apply an enhancing filter to the data.

12. A system in accordance with claim 9 wherein to perform filtering on the data, said system is configured to apply a smoothing filter to the data.

13. A system in accordance with claim 9 wherein to filter the data, said system is configured to filter the data in accordance with (d, 1-2d, d) where:

space="preserve" listing-type="equation">d=m(1-sin (γ

)/γ

).

14.

14. A system in accordance with claim 9 wherein said detector is a single slice detector.

15. A system in accordance with claim 9 wherein said detector is a multislice detector.

16. A system in accordance with claim 9 wherein said filtering also is data acquisition system gain dependent.