METHODS AND APPARATUS FOR OBTAINING LOW-DOSE IMAGING

• US 20090274272A1
• Filed: 07/02/2009
• Published: 11/05/2009
• Est. Priority Date: 11/09/2005
• Status: Active Grant

• Current Assignee: Dexela Limited (Varex Imaging Corporation)
• Original Assignee: Dexela Limited (Varex Imaging Corporation)
• Inventors: Bullard, Edward, Stewart, Alexander, Stanton, Martin
• Granted Patent: US 7,940,885 B2
• Time in Patent Office: Days
• US Class Current: 378/62
• CPC Class Codes: A61B 6/02 Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
• CPC Class Codes: A61B 6/405 Source units specially adapted to modify characteristics of the beam during the data acquisition process A61B6/4021, A61B6/4035 take precedence
• CPC Class Codes: A61B 6/4233 using matrix detectors
• CPC Class Codes: A61B 6/4291 the detector being combined with a grid or grating
• CPC Class Codes: A61B 6/466 adapted to display 3D data
• CPC Class Codes: A61B 6/482 involving multiple energy imaging
• CPC Class Codes: A61B 6/502 for diagnosis of breast, i.e. mammography
• CPC Class Codes: A61B 6/5258 involving detection or reduction of artifacts or noise
• CPC Class Codes: A61B 6/542 involving control of exposure
• CPC Class Codes: G01N 2223/423 multispectral imaging-multiple energy imaging
• CPC Class Codes: G01N 23/04 and forming images of the material

Abstract

In one aspect, A method of imaging an object of interest positioned in an exposure area is provided. The method comprises obtaining projection data of the object by providing radiation to the exposure area and detecting at least some of the radiation exiting the object to form the projection data, performing a first reconstruction of the projection data to form at least one bootstrap image, obtaining first data based on information provided by the at least one bootstrap image, and performing a second reconstruction of the projection data based, at least in part, on the first data to form at least one second image.

Claims

1. A method of imaging an object of interest positioned in an exposure area, the method comprising:

obtaining projection data by providing radiation to the exposure area and detecting at least some of the radiation exiting the object to form the projection data;

arranging at least one density fiducial in the exposure area, prior to obtaining projection data, such that at least some of the radiation provided encounters the at least one density fiducial;

obtaining first data based on information provided by the at least one density fiducial;

modifying the projection data based, at least in part, on the first data; and

reconstructing the modified projection data to form at least one image.

2. The method of claim 1, wherein arranging the at least one fiducial includes arranging at least one proximal density fiducial between the radiation source and the object and at least one distal density fiducial between the object and the detector, wherein the at least one proximal density fiducial and the at least one distal density fiducial are partially transmissive.

3. The method of claim 2, wherein obtaining the first data includes obtaining an estimate of scattered radiation from information provided by the at least one proximal density fiducial and the at least one distal density fiducial.

4. The method of claim 3, wherein the estimate of scattered radiation is obtained by comparing a first radiation intensity detected in a shadow of the at least one proximal density fiducial with a second radiation intensity detected in a shadow of the at least one distal density fiducial.

5. The method of claim 2, wherein the estimate of the scattered radiation is used to modify the projection data to remove at least some of the information resulting from scattered radiation.

6. The method of claim 2, wherein the at least one proximal density fiducial and the at least one distal density fiducial each have a density in a range of 75-150% of a characteristic density of the object.

7. The method of claim 6, wherein the object is a human female breast and the at least one proximal density fiducial and the at least one distal density fiducial each have a density in a range of 75-150% of a healthy breast tissue.

8. The method of claim 1, wherein arranging the at least one fiducial includes arranging at least one proximal density fiducial, between the object and a radiation source, that is substantially opaque to the radiation, and wherein obtaining the first data includes obtaining an estimate of scattered radiation from a radiation intensity detected in a shadow of the at least one proximal density fiducial.

9. A method of imaging an object of interest positioned in an exposure area, the method comprising:

arranging an anti-scatter grid within the exposure area to block a substantial portion of scattered radiation;

obtaining anti-scatter projection data of the object by providing radiation to the exposure area at a first view angle in the presence of an anti-scatter grid, and detecting at least some radiation exiting the exposure area;

obtaining first reconstruction projection data of the object by providing radiation to the exposure area at the first view angle without the anti-scatter grid, and detecting at least some radiation exiting the exposure area;

comparing the anti-scatter projection data with the reconstruction projection data to obtain an estimate of scattered radiation;

modifying the first reconstruction projection data based, at least in part, on the estimate of the scattered radiation;

obtaining second reconstruction projection data of the object by providing radiation to the exposure area at least one second view angle without the anti-scatter grid, and detecting at least some radiation exiting the exposure area;

modifying the second reconstruction projection data based, at least in part, on the estimate of the scattered radiation; and

reconstructing the first reconstruction projection data and the second reconstruction projection data to form at least one image.

10. The method of claim 9, wherein comparing includes subtracting the anti-scatter projection data from the reconstruction projection data to obtain the estimate of the scattered radiation.

11. The method of claim 10, wherein obtaining the second reconstruction projection data includes obtaining second reconstruction projection data from a plurality of different view angles, and wherein modifying the second reconstruction projection data includes modifying the second reconstruction projection data from each of the plurality of different view angles based, at least in part, on the estimate of the scattered radiation.

12. A method of detecting motion of an object of interest positioned in an exposure area during an imaging procedure that includes exposing the object to radiation at a plurality of view angles, the method comprising:

obtaining first projection data of the object by exposing the object to radiation at a first view angle and detecting at least some of the radiation exiting the object from the first view angle;

obtaining second projection data by exposing the object to radiation from at least one second view angle and detecting at least some of the radiation exiting the object from the at least one second view angle;

obtaining third projection data by again exposing the object to radiation at the first view angle and detecting at least some of the radiation exiting the object form the first view angle; and

automatically comparing the first projection data and the third projection data to determine if the object has moved appreciably between obtaining the first projection data and obtaining the third projection data.

13. The method of claim 12, wherein the first projection data is obtained at a beginning of the imaging procedure, and the third projection data is obtained at an end of the imaging procedure.

14. The method of claim 12, wherein automatically comparing the first projection data and the third projection data includes subtracting the third projection data from the first projection data.

15. The method of claim 12, wherein automatically comparing the first projection data and the third projection data includes correlating the third projection data with the first projection data.

16. The method of claim 12, further comprising generating an alert if automatically comparing the first projection data and the second projection data indicates that the object has moved appreciably.

17. The method of claim 16, further comprising reconstructing the first projection is data and the second projection data to form at least one image if automatically comparing the first projection data and the second projection data indicates that the object remained substantially motionless.