# US 2014/0192951 A1 · X-ray ct apparatus and optimal cardiac phase determining method

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- Number: US 2014/0192951 A1
- Document ID: US20140192951A1
- Status: Published application
- Kind: A1
- Application number: 14/122,376
- Filed: 2012-06-19
- Published: 2014-07-10
- Earliest claimed: 2011-06-20
- Assignees: Hitachi Medical Corporation
- Applicants: Hitachi Medical Corporation
- Inventors: Ryota Kohara
- Web page: https://patentgrep.com/patent/US20140192951A1

## CPC

- G06T 12/10: Image preprocessing, e.g. calibration, positioning of sources or scatter correction
- A61B 5/352: Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
- A61B 6/032: {Transmission computed tomography [CT]}
- A61B 6/4078: {Fan-beams}
- A61B 6/4233: {using matrix detectors}
- A61B 6/503: {for diagnosis of the heart}
- A61B 6/5205: {involving processing of raw data to produce diagnostic data}
- A61B 6/5288: {involving retrospective matching to a physiological signal}
- G06T 2211/412: Dynamic
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

In order to provide an X-ray CT apparatus and the like that can specify an optimal cardiac phase in a wide variety of cases, an X-ray CT apparatus collects X-ray information and electrocardiographic waveform data 5 by performing cardiac scanning using an scanning unit 1 (step S11). Then, reconstructed images of a plurality of cardiac phases are created (step S12), and a region-of-interest image is generated by extracting a region of interest for each of the reconstructed images of the plurality of cardiac phases (step S13). Then, a variation distribution image is generated by calculating a variation for each region-of-interest image (step S14). Then, the degree of harmony of each cardiac phase is calculated using the variation distribution image (step S15). Then, an optimal cardiac phase is determined on the basis of at least the degree of harmony (step S16).

## Claims

### Claim 1

An X-ray CT apparatus, comprising:
an X-ray irradiation unit that irradiates X-rays from periphery of an object;
an X-ray detection unit that detects information of X-rays transmitted through the object;
an electrocardiographic information acquisition unit that acquires electrocardiographic information of the object;
an image creation unit that creates an image of the object from the X-ray information and the electrocardiographic information;
a display unit that displays the image;
a tomographic data creation unit that creates a plurality of pieces of tomographic data with different cardiac phases from the X-ray information and the electrocardiographic information;
a region data generation unit that generates region data by extracting a predetermined region for each piece of the tomographic data;
a variation distribution calculation unit that calculates a variation distribution within the tomographic data by calculating a variation between cardiac phases regarding the region data; and
a degree-of-harmony calculation unit that calculates a degree of harmony, which is an index indicating whether or not rhythms at respective locations of a target portion of the object are in harmony with each other, on the basis of the variation distribution.

### Claim 2 (depends on 1)

The X-ray CT apparatus according to claim 1,
wherein the degree-of-harmony calculation unit divides the region data into a plurality of blocks on the basis of the variation distribution, and calculates the degree of harmony on the basis of an area of each of the blocks and the variation of each of the blocks.

### Claim 3 (depends on 1)

The X-ray CT apparatus according to claim 1,
wherein the variation distribution calculation unit calculates an amount of difference for the region data of adjacent cardiac phases, specifies a target region from a region having the amount of difference equal to or greater than a predetermined value, sets a region located around the target region, in the region having the amount of difference equal to or greater than the predetermined value, as a peripheral region, and calculates the variation by giving a weighting to the amount of difference of the target region on the basis of a difference between the amount of difference of the target region and the amount of difference of the peripheral region and an inter-region distance between the target region and the peripheral region.

### Claim 4 (depends on 1)

The X-ray CT apparatus according to claim 1, further comprising:
an optimal cardiac phase determination unit that determines an optimal cardiac phase from a plurality of cardiac phases using at least the degree of harmony.

### Claim 5 (depends on 2)

The X-ray CT apparatus according to claim 2,
wherein the degree-of-harmony calculation unit arranges the blocks, which are divided first, according to a degree of association between the blocks divided first.

### Claim 6 (depends on 2)

The X-ray CT apparatus according to claim 2,
wherein the degree-of-harmony calculation unit displays the blocks on the display unit according to a degree of association between the blocks divided first.

### Claim 7 (depends on 6)

The X-ray CT apparatus according to claim 6,
wherein the degree-of-harmony calculation unit displays blocks, which are highly associated with each other compared with a degree of association with other blocks, on the display unit by the same pattern.

### Claim 8 (depends on 6)

The X-ray CT apparatus according to claim 6,
wherein the degree-of-harmony calculation unit connects blocks, which are highly associated with each other compared with a degree of association with other blocks, to each other and displays a result on the display unit.

### Claim 9 (depends on 6)

The X-ray CT apparatus according to claim 6,
wherein the degree-of-harmony calculation unit displays the blocks on the display unit in a tree structure according to the degree of association.

### Claim 10

An optimal cardiac phase determining method in an X-ray CT apparatus comprising an X-ray irradiation unit that irradiates X-rays from periphery of an object, an X-ray detection unit that detects information of X-rays transmitted through the object, an electrocardiographic information acquisition unit that acquires electrocardiographic information of the object, an image creation unit that creates an image of the object from the X-ray information and the electrocardiographic information, and a display unit that displays the image, the method including:
creating a plurality of pieces of tomographic data with different cardiac phases from the X-ray information and the electrocardiographic information;
generating region data by extracting a predetermined region for each piece of the tomographic data;
calculating a variation distribution within the tomographic data by calculating a variation between cardiac phases regarding the region data; and
calculating a degree of harmony, which is an index indicating whether or not rhythms at respective locations of a target portion of the object are in harmony with each other, on the basis of the variation distribution.