Method and apparatus for generating an improved image of natural tissue in reconstructing body images from 3D-measurements

• US 7,103,135 B2
• Filed: 07/24/2003
• Issued: 09/05/2006
• Est. Priority Date: 08/14/2002
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Op De Beek, Johannes Catharina Antonius, Koppe, Reiner, Klotz, Erhard Paul Artur
• Primary Examiner(s): Glick, Edward J.
• Assistant Examiner(s): KAO, CHIH CHENG G
• Application Number:
  US10/524,422
• Publication Number:
  US 20050238133A1
• Time in Patent Office: 1,139 Days
• Field of Search: 378/4, 378/8, 378/15, 378/22, 378/901
• US Class Current: 378/4
• CPC Class Codes: A61B 6/5258 involving detection or reduction of artifacts or noise
• CPC Class Codes: G06T 11/005 Specific pre-processing for tomographic reconstruction, e.g. calibration, source positioning, rebinning, scatter correction, retrospective gating
• CPC Class Codes: G06T 2200/04 involving 3D image data
• CPC Class Codes: G06T 2207/10081 Computed x-ray tomography [CT]
• CPC Class Codes: G06T 2207/30004 Biomedical image processing
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/77 Retouching; Inpainting; Scratch removal
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06T 7/136 involving thresholding
• CPC Class Codes: Y10S 378/901 Computer tomography program or processor

Abstract

A method is disclosed for generating images of a human or animal body on the basis of 3D-reconstructions from 3D-XRAY or 3D-Computer Tomography measurements, which bodies comprise both natural tissue and one or more high-density objects. The method comprises the steps of executing the measurements, distinguishing the one or more high-density objects and executing a separating procedure thereon for generating an improved image of regions of the natural tissue. In particular, the method comprises the following steps: applying a ramp filter on the various projection measurements to single out the one or more high-density objects; segmenting the singled-out one or more high-density objects into a separate 3D reconstruction; suppressing the reconstructed one or more high-density objects from the original projection measurements; and segmenting said projection measurements without the suppressed one or more high-density objects.

Claims

1. An apparatus for generating images of a subject on the basis of 3D-reconstructions from 3D-XRAY or 3D-Computer Tomography measurements, which subject comprises both natural tissue and one or more high-density objects, said apparatus comprising a measuring facility for executing said measurements, a distinguishing facility for distinguishing said one or more high-density objects and executing a separating procedure thereon for generating an image of regions of said natural tissue,

said apparatus being characterized by comprising:

a ramp-filtering facility for applying a ramp filter in the direction of rotation to various projection measurements and a back-projecting facility fed by said ramp-filtering facility for back-projecting the various filtered projections into a 3D-volume reconstruction;

a segmenting facility fed by said back-projecting facility for segmenting in said 3D-volume reconstruction said one or more high-density objects by a thresholding procedure and a forward projecting facility fed by said segmenting facility for executing a forward projection of a shadow(s) of the segmented one or more high-density objects onto the ramp-filtered projection, whilst marking borders of said one or more high-density objects in the ramp-filtered projections;

a suppressing facility fed by said forward projecting facility for suppressing the reconstructed one or more high-density objects from the original projection measurements and said suppressing facility is operative for executing an appropriate substitution of gray values derived from a physical neighbourhood of said one or more high-density objects instead of said one or more high-density objects in question;

and a retro-coupling facility fed by said suppressing facility for executing a back-projection of the various filtered projections with corrected profiles through exclusion of the suppressed one or more high-density objects and outputting a reconstruction result.

2. An apparatus as claimed in claim 1, and furthermore comprising a superimposing facility fed by said forward projecting facility for receiving said one or more high-density objects for superimposing thereof onto said reconstruction result.

3. An apparatus as claimed in claim 1, and furthermore comprising adapting means for relatively adapting the gray values of said one or more high-density objects and said natural tissue in a predetermined gray value range to show both of said one or more highdensity objects and said natural tissue at same time.

4. A method of generating images of a human or animal body on the basis of 3D-reconstructions from 3D-XRAY or 3D-Computer Tomography measurements, which body comprises both natural tissue and one or more high-density objects, said method comprising the steps of executing said measurements, distinguishing said one or more high-density objects and executing a separating procedure thereon for generating an improved image of regions of said natural tissue,

said method being characterized by comprising the steps of:

applying a ramp filter in the direction of rotation to various projection measurements and back-projecting the various filtered projections into a 3D-volume reconstruction;

in said 3D-volume reconstruction, segmenting said one or more high-density objects by a thresholding procedure and executing a forward projection of a shadow(s) of the segmented one or more high-density objects onto the ramp-filtered projection, whilst marking borders of said one or more high density objects in the ramp-filtered projections;

suppressing the reconstructed one or more high-density objects from the original projection measurements whilst executing an appropriate substitution of gray values derived from a physical neighbourhood of said one or more high-density objects instead of said one or more high-density objects in question;

and secondarily executing a back-projection of the various filtered projections with corrected profiles and thereby without the suppressed one or more high-density objects.

5. A computer readable medium containing instructions for controlling a computer system to perform the steps of a method of generating images of a subject on the basis of 3D-reconstructions from 3D-XRAY or 3D-Computer Tomography measurements, which subject comprises both natural tissue and one or more high-density objects, said method comprising the steps of executing said measurements, distinguishing said one or more high-density objects and executing a separating procedure thereon for generating an improved image of regions of said natural tissue,

said method furher comprising the steps of:

applying a ramp filter in the direction of rotation to various projection measurements and back-projecting the various filtered projections into a 3D-volume reconstruction,

in said 3D-volume reconstruction, segmenting said one or more high-density objects by a thresholding procedure and executing a forward projection of a shadow(s) of the segmented one or more high-density objects onto the ramp-filtered projection, whilst marking borders of said one or more high density objects in the ramp-filtered projections;

suppressing the reconstructed one or more high-density objects from the original projection measurements whilst executing an appropriate substitution of gray values derived from a physical neighbourhood of said one or more high-density objects instead of said one or more high-density objects in question;

and secondarily executing a back-projection of the various filtered projections with corrected profiles and thereby without the suppressed one or more high density objects.