Method of reducing artifacts in object images

• US 20020150200A1
• Filed: 03/26/2002
• Published: 10/17/2002
• Est. Priority Date: 03/29/2001
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Zonneveld, Frans Wessel
• Granted Patent: US 6,542,571 B2
• Time in Patent Office: Days
• US Class Current: 378/4
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: Y10S 378/901 Computer tomography program or processor

Abstract

The invention concerns a method of reducing artifacts in object images acquired by means of measurement signals sent by a source through the object onto a detector, which method comprises the steps of: a) adaptively filtering the data signals received by the detector in dependence of the data value; b) processing the data signals to indicate the attenuation of the measurement signals passing through the object; and c) reconstructing an image of the object based on the filtered and processed data signals. The method according to the invention is characterized in that step b) is performed on the adaptively filtered data signals resulting from step a).

The invention also refers to a computed tomography device that comprises a processing unit for carrying out the method according the invention and to a computer program for carrying out said method.

Claims

1. A method of reducing artifacts in object images acquired by means of measurement signals sent by a source through the object onto a detector, which method comprises the steps of:

a) adaptively filtering the data signals received by the detector in dependence of the data value;

b) processing the data signals to indicate the attenuation of the measurement signals passing through the object; and

c) reconstructing an image of the object based on the filtered and processed data signals, characterized in that step b) is performed on the adaptively filtered data signals resulting from step a).

2. A method according to claim 1, wherein step a) comprises the steps of filtering essentially all data signals having a value below a predetermined ceiling value.

3. A method according to claim 2, wherein the ceiling value is related to the noise present on the data signals.

4. A method according to claim 2 or 3, wherein the ceiling value essentially equals three times the standard deviation of the noise.

5. A method according to one or more of the preceding claims, wherein step a) further comprises the step of filtering each of the data signals with neighboring data signals.

6. A method according to claim 5, wherein the filtering is performed with neighboring data signals located in lateral direction of the detector.

7. A method according to claim 5 or 6, wherein the filtering is performed with neighboring data signals located in longitudinal direction of the object.

8. A computed tomography device comprising

an X-ray source for irradiating an object by means of X-rays from different axial directions;

and

an X-ray detector;

wherein the X-ray source and X-ray detector are displaceable relative to the object in longitudinal direction thereof and the X-ray detector is arranged to measure a plurality of density profiles for respective axial directions and longitudinal positions, which density profiles form an object data set of data signal values,

which computed tomography device comprises a processing unit for carrying out the method according to one or more of the preceding claims.

9. A computed tomography device according to claim 8, wherein the X-ray detector is a two-dimensional detector.

10. Computer program for carrying out the method according to one or more of the preceding claims 1 through 7.