X-ray CT apparatus and image reconstruction method

Patent metadata

Field	Value
Publication number	US-10433803-B2
Application number	US-201515313707-A
Country	US
Kind code	B2
Filing date	Jun 16, 2015
Priority date	Jun 19, 2014
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

Abstract

An X-ray CT apparatus and an image reconstruction method are configured (i) to determine a movement phase to be used for generating diagnostic images with a small number of operations and (ii) to acquire diagnostic images in a short time while reducing a burden on an operator, such as when the target in scanning is a moving site. For example, an image processing device of an X-ray CT apparatus obtains movement information of a diagnostic site (such as the heart), determines phase selection positions, permits the operator to select an arbitrary movement phase based on the acquired movement information, and reconstructs selection images in a plurality of movement phases for each of the determined phase selection positions using scan data before presentation.

First claim

The invention claimed is:

1. An X-ray CT apparatus comprising:
an X-ray source that generates X-rays;
an X-ray detector that is placed opposite to the X-ray source and detects X-rays transmitted through an object;
a data acquisition device that acquires scan data corresponding to the transmission X-rays detected by the X-ray detector;
a movement information measuring device that measures movement information of a diagnostic site in or on the object;
a selection image generation unit that obtains the scan data and the movement information of the diagnostic site during scanning, determines phase selection positions based on the obtained scan data or the movement information, and generates, based on the scan data and for each of the phase selection positions, plural selection images corresponding to a plurality of respective movement phases;
a presentation unit that presents the selection images generated by the selection image generation unit;
a phase selection unit that receives, for each of the phase selection positions, selection of an arbitrary movement phase associated with a corresponding selection image selected by an operator from the selection images, presented by the presentation unit and corresponding to the respective movement phases;
a calculating unit that calculates, based on the selected movement phase for said each of the phase selection positions which correspond to respective body-axis direction positions, a movement phase distribution which shows an optimal movement phase of the entire diagnostic site; and
a diagnostic image generating unit that determines, based on the movement phase distribution and for reconstructing diagnostic images corresponding to the respective body-axis direction positions, diagnostic phases corresponding to the respective diagnostic images to be reconstructed, and reconstructs the diagnostic images corresponding to the diagnostic phases.

2. The X-ray CT apparatus according to claim 1 ,
wherein the phase selection positions are provided using a period of the movement information as a reference.

3. The X-ray CT apparatus according to claim 1 , further comprising:
an extraction unit that generates evaluation images of the diagnostic site based on the scan data and extracts a site presenting anatomical features or at least a portion of the diagnostic site, from the evaluation images,
wherein the selection image generation unit determines, based on the site extracted by the extraction unit, the phase selection positions which correspond to the respective body-axis direction positions of the diagnostic images to be generated by the diagnostic image generating unit.

4. The X-ray CT apparatus according to claim 1 ,
wherein the phase selection positions are set as the body-axis direction positions scanned at a time when the movement information has an abnormality.

5. The X-ray CT apparatus according to claim 1 ,
wherein the phase selection positions are set as the body-axis direction positions excluding scanning positions at a time when the movement information has an abnormality.

6. The X-ray CT apparatus according to claim 1 ,
wherein the calculating unit sets the movement phase distribution as a curve or a straight line to be evaluated based on a relationship between the phase selection positions and the movement phases selected in each phase selection position.

7. The X-ray CT apparatus according to claim 1 ,
wherein each of the movement phases is represented by a percentage of an interval between R-waves, and the calculating unit sets the movement phase distribution as an average value of movement phases selected in a plurality of the phase selection positions.

8. The X-ray CT apparatus according to claim 1 ,
wherein the calculating unit further receives correction of the calculated movement phase distribution.

9. The X-ray CT apparatus according to claim 1 , further comprising:
a selection priority setting unit that sets and stores, for each phase selection position amongst the phase selection positions, a selection priority associated with the phase selection position,
wherein the presentation unit presents the selection images of the plurality of movement phases in priority order in which each selection image corresponding to a phase selection position associated with a selection priority that is higher than those of remaining selection images is presented prior to said remaining selection images.

10. The X-ray CT apparatus according to claim 1 , further comprising:
a controller that controls X-ray exposure based on movement information during scanning,
wherein the selection image generation unit evaluates differences between planned movement phases which were previously planned before scanning and actually exposed movement phases and determines the phase selection positions using the evaluated differences as references.

11. The X-ray CT apparatus according to claim 1 ,
wherein the presentation unit displays an entire image illustrating an entire diagnostic site with the selection images and provides guide displays on the entire image corresponding to body-axis direction positions of the selection images.

12. The X-ray CT apparatus according to claim 11 , further comprising:
a phase selection position addition unit that adds an additional phase selection position,
wherein the selection image generation unit further generates selection images of a plurality of movement phases for the additional phase selection position.

13. An image reconstruction method performed by an image processing device, the method including the steps of:
(a) obtaining scan data that were measured by an X-ray CT apparatus and movement information of a diagnostic site during scanning, determining phase selection positions based on the obtained scan data or the acquired movement information, and generating, based on the scan data and for each of the phase selection positions, plural selection images corresponding to a plurality of respective movement phases;
(b) presenting the selection images generated by (a);
(c) determining, for each of the phase selection positions, an arbitrary movement phase associated with a corresponding selection image selected by an operator from the selection images, presented by (b) and corresponding to the respective movement phases;
(d) calculating, based on the arbitrary movement phase for said each of the phase selection positions which correspond to respective body-axis direction positions, a movement phase distribution which shows an optimal movement phase of the entire diagnostic site; and
(e) determining, based on the movement phase distribution and for reconstructing diagnostic images corresponding to the respective body-axis direction positions, diagnostic phases corresponding to the respective diagnostic images to be reconstructed, and reconstructing the diagnostic images corresponding to the diagnostic phases.

Assignees

• Hitachi Ltd

Inventors

• Kokubun Hiroto

Classifications

• A61B6/5217 Primary

  extracting a diagnostic or physiological parameter from medical diagnostic data · CPC title

• G06T2207/30048

  Heart; Cardiac · CPC title

• G06T7/38

  Registration of image sequences · CPC title

• A61B5/0205

  Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition · CPC title

• A61B6/032 Primary

  Transmission computed tomography [CT] · CPC title