METHOD AND APPARATUS FOR REDUCING ARTEFACTS IN COMPUTED TOMOGRAPHY IMAGES

• US 20170150937A1
• Filed: 05/12/2015
• Published: 06/01/2017
• Est. Priority Date: 05/14/2014
• Status: Active Grant

• Current Assignee: Universitaet Zu Luebeck Institut Fuer Medizintechnik
• Original Assignee: Universitaet Zu Luebeck Institut Fuer Medizintechnik
• Inventors: STILLE, Maik, BUZUG, Thorsten M.
• Granted Patent: US 9,980,695 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/12 Arrangements for detecting or locating foreign bodies
• CPC Class Codes: A61B 6/5205 involving processing of raw data to produce diagnostic data
• 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 11/006 Inverse problem, transformation from projection-space into object-space, e.g. transform methods, back-projection, algebraic methods
• CPC Class Codes: G06T 2207/10081 Computed x-ray tomography [CT]
• CPC Class Codes: G06T 2211/424 Iterative
• CPC Class Codes: G06T 2211/448 involving metal artefacts, streaking artefacts, beam hardening or photon starvation

Abstract

The invention relates to a method and an apparatus for reducing artefacts that are caused particularly by disturbance bodies and/or metal bodies in computed tomography (CT) images by means of a regulated iteration process that can be integrated particularly into a process for processing measurement data and preferably into a superordinate process for data alignment.

Claims

1. A method for reducing artefacts in computed tomography (CT) images which are caused particularly by obstructive bodies and/or metal bodies, wherein the following sequence of steps is performed in at least one iteration process:

(a) reconstructing or generating CT image data from first projection data,

(b) querying one or more limiting values and/or terminating conditions of the iteration process and, in the case of the limiting values being reached and/or the terminating conditions being met, aborting the iteration process and outputting the CT image data, otherwise continuing the iteration process with step (c),

(c) reducing artefacts in the reconstructed/generated CT image data by filtering the CT image data,

(d) generating second projection data from the filtered CT image data,

(e) combining the first and second projection data, in particular replacing the first projection data by the second projection data in due consideration of the obstructive body data and transferring the projection data thereby obtained to step (a) as the first projection data.

2. The method for reducing artefacts according to claim 1, wherein the at least one iteration process is integrated into a further process having the following steps:

(f) generating the obstructive body data, particularly obstructive body projection data, on the basis of the obstructive body-characterizing parameters stored in particular in a database,

(g) collecting/acquiring first projection data and parameterizing said first projection data,

(h) verifying whether an obstructive body is present in the object based on the first projection data,

(i) processing, in particular masking and/or filtering and/or interpolating the first projection data and transferring the processed first projection data to step (a) and (f).

3. The method for reducing artefacts according to claim 1,

wherein the at least one iteration process is integrated, in particular together with the further process, into a superordinate process having the following steps:

(j) starting the method,

(k) inputting of data, particularly patient-related data,

(l) retrieving parameters characterizing an obstructive body and/or data identifying an obstructive body from a database, in particular an electronic patient record, on the basis of the entered data,

(m) transferring the retrieved parameters/data to step (f) and/or step (g), in particular subsequent verification and, if applicable, supplementation and/or correction of the parameters/data.

5. The method for reducing artefacts according to claim 2, wherein the at least one iteration process is integrated, in particular together with the further process, into a superordinate process having the following steps:

(n) starting the method,

(o) inputting of data, particularly patient-related data,

(p) retrieving parameters characterizing an obstructive body and/or data identifying an obstructive body from a database, in particular an electronic patient record, on the basis of the entered data,

(q) transferring the retrieved parameters/data to step (f) and/or step (g), in particular subsequent verification and, if applicable, supplementation and/or correction of the parameters/data.

4. An apparatus for reducing artefacts in computed tomography (CT) images which are caused particularly by obstructive bodies and/or metal bodies, wherein at least one iterative control loop configured to perform the following sequence of steps:

(a) reconstructing or generating CT image data from first projection data,

(b) querying one or more limiting values and/or terminating conditions of the iteration process and, in the case of the limiting values being reached and/or the terminating conditions being met, aborting the iteration process and outputting the CT image data, otherwise continuing the iteration process with step (c),

(c) reducing artefacts in the reconstructed/generated CT image data by filtering the CT image data,

(d) generating second projection data from the filtered CT image data,

(e) combining the first and second projection data, in particular replacing the first projection data by the second projection data in due consideration of the obstructive body data and transferring the projection data thereby obtained to step (a) as the first projection data.