# US 2014/0153803 A1 · Image processing apparatus and image processing method

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- Number: US 2014/0153803 A1
- Document ID: US20140153803A1
- Status: Published application
- Kind: A1
- Application number: 14/077,328
- Filed: 2013-11-12
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: Canon Kabushiki Kaisha
- Applicants: Canon Kabushiki Kaisha
- Inventors: Takeshi Noda
- Web page: https://patentgrep.com/patent/US20140153803A1

## CPC

- G06T 7/0012: {Biomedical image inspection}
- G06T 12/20: Inverse problem, i.e. transformations from projection space into object space
- G06T 2211/424: Iterative
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL

## Abstract

An image processing apparatus for reconstructing a tomographic image from a plurality of projection images acquires noise data for a plurality of projection images, respectively, acquires noise reconstruction data by executing reconstruction processing based on the acquired noise data, and reconstructs the tomographic image by executing the reconstruction processing based on the projection images and the noise reconstruction data.

## Claims

### Claim 1

An image processing apparatus for reconstructing a tomographic image from a plurality of projection images, comprising:
an acquisition unit configured to acquire noise data for the plurality of projection images, respectively;
a reconstruction processing unit; and
a control unit configured to execute first control for obtaining noise reconstruction data based on the noise data acquired by said acquisition unit, and second control for reconstructing the tomographic image based on the projection images and the noise reconstruction data by said reconstruction processing unit.

### Claim 2 (depends on 1)

The apparatus according to claim 1, wherein said control unit is configured to reconstruct the tomographic image using an iterative reconstruction method in the second control.

### Claim 3 (depends on 2)

The apparatus according to claim 2, wherein said control unit is configured to determine a regulation term used in reconstruction of the tomographic image by the iterative reconstruction method based on the noise reconstruction data.

### Claim 4 (depends on 3)

The apparatus according to claim 3, wherein said control unit is configured to determine the regulation term so that a degree of regulation undergone by an area increases as noise represented by the noise reconstruction data in the tomographic image increases.

### Claim 5 (depends on 1)

The apparatus according to claim 1, wherein said control unit is configured to determine the regulation term so that a degree of regulation undergone by an area increases as contrast in the tomographic image increases.

### Claim 6 (depends on 1)

The apparatus according to claim 1, wherein said control unit is configured to reconstruct the tomographic image by filtered back projection using a reconstruction filter in the second control, and to process the noise data to obtain the noise reconstruction data using the reconstruction filter in the first control.

### Claim 7 (depends on 6)

The apparatus according to claim 6, wherein said control unit is configured, in the first control, to calculate noise power using a standard deviation of noise of the projection images and a filter coefficient of the reconstruction filter, and to obtain the noise reconstruction data by back projecting the noise power.

### Claim 8 (depends on 1)

The apparatus according to claim 1, wherein said acquisition unit is configured to obtain a noise amount of each pixel in accordance with a pixel value of the projection images to acquire the noise data.

### Claim 9 (depends on 1)

The apparatus according to claim 1, further comprising a transmission unit configured to transmit a control signal to an X-ray detector for acquiring the projection images.

### Claim 10

An image processing method of reconstructing a tomographic image from a plurality of projection images, the method comprising:
acquiring noise data for the plurality of projection images, respectively;
acquiring noise reconstruction data by executing reconstruction processing based on the acquired noise data; and
reconstructing the tomographic image by executing the reconstruction processing based on the projection images and the noise reconstruction data.

### Claim 11 (depends on 10)

A non-transitory computer-readable storage medium storing a program which, when run on a computer, causes the computer to execute an image processing method according to claim 10.