US5043890A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Compensation of computed tomography data for objects positioned outside the field of view of the reconstructed image
Assignee: General Electric Co
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Filing: 1989-06-12
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Granted: 1991-08-27
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Expires: 2009-06-12
Abstract
Abstract An x-ray CT system acquires attenuation data over a field of view which is larger than the field of view of the reconstructed image. The data used to reconstruct the image is compensated for the shading effects otherwise caused by objects outside the image, but within the x-ray path. This compensation is accomplished with minimal impact on computation time by using a first order estimation of the convolution of the acquired attenuation data outside the image field of view.
Inventors
- 👤 Kevin F. King
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:47
CPC Classifications
G; G06; G06T; G06T12/00; G06T12/10; G06T2211/00; G06T2211/40; G06T2211/432
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
153 words
A method for producing an image with a CT system, the steps comprising: acquiring a set of transmission profiles, each transmission profile containing a set of attenuation values in a central region which corresponds to the field of view of the image to be reconstructed, and sets of attenuation values located in peripheral regions to each side of the central region; convoluting the central region of each transmission profile in the acquired set of transmission profiles with a convolution kernel to produce processed data; estimating the convolution of the sets of attenuation values in the peripheral regions of the transmission profiles by multiplying the convolution kernel by a single attenuation value which is the sum of the attenuation values in each peripheral region; compensating the processed data by adding the peripheral region estimates to the processed data to produce compensated processed data; and reconstructing an image by back projecting the compensated processed data.
Claim 2
Independent Claim
153 words
A method for producing an image with a CT system, the steps comprising: acquiring a set of transmission profiles, each transmission profile containing a set of attenuation values in a central region which corresponds to the field of view of the image to be reconstructed, and sets of attenuation values located in peripheral regions to each side of the central region; convoluting the central region of each transmission profile in the acquired set of transmission profiles with a convolution kernel to produce processed data; estimating the convolution of the sets of attenuation values in the peripheral regions of the transmission profiles by multiplying the convolution kernel by a single attenuation value which is the sum of the attenuation values in each peripheral region; compensating the processed data by adding the peripheral region estimates to the processed data to produce compensated processed data; and reconstructing an image by back projecting the compensated processed data.
Claim 3
Dependent Claim
63 words
The method as recited in claim 1 in which the convolution of each set of attenuation values in a peripheral region is estimated by multiplying the convolution kernel by a single attenuation value which is located at the center of mass of the peripheral region and which has an amplitude equal to the sum of all the attenuation values in the peripheral region.
Claim 4
Dependent Claim
42 words
The method as recited in claim 2 in which the estimated convolution of attenuation values in each peripheral region is an array of estimated attenuation values and selected ones of these estimated attenuation values are added to elements of the processed data.
References Cited (Backward Citations)
GB2006566A
Cited
US4305127A
Cited
US4550371A
Cited
EP0107253A1
Cited
US4633398A
Cited
US4606004A
Cited
US4692624A
Cited
EP0242909A1
Cited
US4878169A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-08-26 | 1995-02-25 | 1995-08-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-08-26 | 1999-02-25 | 1999-08-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-08-26 | 2003-02-25 | 2003-08-27 | $7700.00 | Window Closed / Lapsed |