SYSTEM AND METHOD FOR OCT DEPTH CALIBRATION

• US 20140270445A1
• Filed: 03/12/2014
• Published: 09/18/2014
• Est. Priority Date: 03/13/2013
• Status: Active Grant

• Current Assignee: Volcano Corporation (Koninklijke Philips N.V.)
• Original Assignee: Volcano Corporation (Koninklijke Philips N.V.)
• Inventors: Kemp, Nathaniel J.
• Granted Patent: US 9,301,687 B2
• Time in Patent Office: Days
• US Class Current: 382/131
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 5/0066 Optical coherence imaging
• CPC Class Codes: A61B 5/0073 by tomography, i.e. reconstruction of 3D images from 2D projections A61B5/0066 takes precedence
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/6852 Catheters

Abstract

The invention generally relates to methods for calibrating an OCT image by comparing a detected location of a feature within the image to an expected location of the feature, calculating a calibration value, and transforming the location of pixels within the image to provide a calibrated image.

Claims

1. A method of calibrating an imaging system, the method comprising:

obtaining an image that includes a target and a reference item;

detecting a location of the reference item within the image;

determining a y-value of the location;

comparing the determined y-value to a stored reference y-value;

calculating a calibration value based on the comparison; and

providing a calibrated image by shifting pixels in a y-direction according to the calibration value.

2. The method of claim 1, wherein the imaging system is an optical coherence tomography system.

3. The method of claim 1, wherein the reference item comprises an image of a catheter sheath.

4. The method of claim 1, wherein the detecting step comprises a morphological image processing operation.

5. The method of claim 1, further comprising digitally transforming image data to provide the calibrated image.

6. The method of claim 1, wherein detecting the location comprises one selected from the list consisting of peak searching, correlation, thresholding, and performing a pattern recognition algorithm.

7. The method of claim 1, further comprising obtaining an a priori range over which a path length displacement may occur.

8. The method of claim 1, wherein determining the y-value comprises averaging across the image.

9. The method of claim 1, wherein calculating the calibration value comprises taking a difference between the determined y-value and the stored reference y-value.

10. The method of claim 9, wherein the pixels are shifted by the difference.

11. The method of claim 1, further comprising removing a feature from the image.

12. The method of claim 1, further comprising removing the reference item from the image.

13. The method of claim 11, wherein removing comprises cropping out the feature across its extent in the y direction at all x positions.

14. The method of claim 13, wherein removing comprises calculating an average value of pixels proximal to the cropped region and inserting the average values to replace the cropped pixels.

15. The method claim 1, wherein the method is performed using a computer system comprising a tangible, non-transitory memory coupled to a processor.

16. An imaging system, the system comprising:

a processor coupled to a non-transitory memory, wherein the system is operable to;

obtain an image that includes a target and a reference item;

detect a location of the reference item within the image;

determine a y-value of the location;

compare the determined y-value to a stored reference y-value;

calculate a calibration value based on the comparison; and

provide a calibrated image by shifting pixels in a y-direction per the calibration value.