Method and Apparatus for Correcting Excess Signals in an Imaging System

• US 20080315105A1
• Filed: 09/05/2008
• Published: 12/25/2008
• Est. Priority Date: 10/16/2002
• Status: Active Grant

• Current Assignee: Varex Imaging Corporation
• Original Assignee: Varian Medical Systems Incorporated (Siemens AG)
• Inventors: Partain, Larry D., Tognina, Carlo, Mollov, Ivan, Colbeth, Richard E.
• Granted Patent: US 7,638,752 B2
• Time in Patent Office: Days
• US Class Current: 250/370.08
• CPC Class Codes: H04N 25/63 applied to dark current
• CPC Class Codes: H04N 5/32 Transforming X-rays cameras or camera modules for generating image signals from X-rays H04N23/30; circuitry of SSIS for transforming X-rays into image signals H04N25/30

Abstract

A method and apparatus for excess signal compensation in an imaging system is described. In one particular embodiment, the invention provides for non-linear background, offset (due to time dependent dark current) and/or lag (including constant, linear and non-linear terms, due to image persistence) corrections of large area, flat panel imaging sensors.

Claims

1. A method, comprising:

estimating an excess signal based on a combination of a first and a second non-linear decay response model of a measured signal of an image frame of an imaging system; and

compensating for the excess signal in the image frame using the estimated excess signal.

2. The method of claim 1, wherein model comprises a non-linear time variant decay response model.

3. The method of claim 1, wherein the model comprises a representation of a measured signal of the image frame.

4. A method, comprising:

estimating an excess signal based on a combination of a non-linear decay response model and a linear decay response model of a measured signal of an image frame of an imaging system; and

compensating for the excess signal in the image frame using the estimated excess signal.

5. The method of claim 4, wherein model comprises a non-linear time variant decay response model.

6. The method of claim 4, wherein the model comprises a representation of a measured signal of the image frame.

7. A method, comprising:

estimating an excess signal based on a non-linear decay response model and a frame rate; and

compensating for the excess signal in the image frame of an imaging system;

wherein the frame rate is faster than one tenth of a frame per second.

8. The method of claim 7, wherein model comprises a non-linear time variant decay response model.

9. The method of claim 7, wherein the model comprises a representation of a measured signal of the image frame, and, wherein the frame rate comprises a frame rate of a measured signal of an image frame.

10. The method of claim 7, further comprising selecting the frame rate.

11. A method, comprising:

estimating an excess signal based on a non-linear decay response model of a combination of saturated and non-saturated frames of a measured signal of an image frame of an imaging system; and

compensating for the excess signal in the image frame using the estimated excess signal.

12. The method of claim 11, wherein model comprises a non-linear time variant decay response model.

13. The method of claim 11, wherein the model comprises a representation of a measured signal of the image frame.

14. A method, comprising:

estimating an excess signal based on a non-linear time variant decay response model of a measured signal of an image frame of an imaging system; and

subtracting the excess signal from the measured signal of the image frame.

15. A method, comprising:

estimating an excess signal based on a non-linear decay response model of a measured signal of an image frame of an imaging system; and

compensating for the excess signal in the image frame, wherein estimating the excess signal further comprises selecting a first reference image frame and selecting a second reference image frame.

16. The method of claim 15, wherein estimating further based on a timed difference between two lag frames, without knowing a frame rate of the imaging system.

17. The method of claim 15, wherein model comprises a non-linear time variant decay response model.

18. The method of claim 15, wherein the model comprises a representation of a measured signal of the image frame.