Image processing device, radiation imaging device, and image processing method

Patent metadata

Field	Value
Publication number	US-2016015351-A1
Application number	US-201414771906-A
Country	US
Kind code	A1
Filing date	Mar 11, 2014
Priority date	Mar 27, 2013
Publication date	Jan 21, 2016
Grant date	—

Abstract

An image processing device or radiation imaging device for generating an image using output data from a detector for detecting a radiation transmitted through an object to be examined, wherein artifacts caused by a gap between an estimated output value and the true output value are reduced when estimating an output value of a defective element of the detector. Correction is performed not only for the output of the defective element but for the output of the surrounding normal elements used for the defective element correction by a blurring process. Additionally, whether or not to perform the blurring process for the surrounding normal elements and the degree of the blurring process are adjusted according to the device conditions, scanning conditions, and the like.

First claim

1 . An image processing device comprising:
an image generation unit that generates an image using projection data composed of output values of the respective detection elements of a detector composed by arranging a plurality of detection elements; and a data correction unit that corrects the incompleteness of the projection data due to a defective element included in the detector, wherein the data correction unit comprises an estimating part that estimates an output value of the defective element and a blurring processing part that performs a blurring process for output values of the detection elements located around the said defective element using an estimated output value estimated for the defective element and sets the estimated output value as an output value for the defective element to perform correction for the detection elements using output values after the blurring process, and the image generation unit generates the image using the projection data corrected by the data correction unit.

2 . The image processing device according to claim 1 , further comprising:
a correction controller that controls a blurring amount or a blurring rate with the blurring processing part.

3 . The image processing device according to claim 2 ,
wherein the correction controller controls a blurring amount or a blurring rate using at least either one of output values of the first adjacent elements located around the defective element, output values of the second adjacent elements located around the first adjacent elements, and an estimated output value of the defective element to be calculated using the output values of the first adjacent elements.

4 . The image processing device according to claim 3 ,
wherein the detector includes a plurality of detection elements arranged in a first direction and a second direction crossing the said first direction, and the blurring processing part estimates a gap amount of an estimated output value estimated by the estimation part from a true value using output values of detection elements in rows and/or columns adjacent to a row and/or column including a defective element for which the estimated output value is estimated from among the plurality of detection element arrays in order to adjust the blurring amount or blurring rate according to the said gap amount.

5 . The image processing device according to claim 2 ,
wherein the correction controller controls the blurring amount or the blurring rate according to the conditions including any of a position of the defective element in the detector, a size of a radiation focus for irradiating a radiation to the detector, and an output noise ratio of the detector.

6 . The image processing device according to claim 5 ,
wherein the correction controller is provided with an input unit that inputs the blurring amount or the blurring rate as well as the conditions to determine the blurring amount or the blurring rate.

7 . The image processing device according to claim 1 ,
wherein the estimating part calculates an estimated output value of the said defective element using output values of the first adjacent elements located around the defective element, and the blurring processing part calculates a blurring amount using at least either one of an estimated output value estimated for the defective element or output values of the second adjacent elements other than the defective element that are located around the first adjacent elements and performs a blurring process by adding the blurring amount to the output values of the first adjacent elements.

8 . The image processing device according to claim 1 ,
wherein the estimating part calculates an estimated output value of the said defective element using output values of the first adjacent elements located around the defective element, and the blurring processing part performs a blurring process using a value for which a first blurring rate is multiplied by an estimated output value estimated for the defective element, output values of the first adjacent elements, and a value for which a second blurring rate is multiplied by output values of the second adjacent elements other than the defective element that are located around the first adjacent elements.

9 . The image processing device according to claim 1 ,
wherein the detector includes a plurality of detection elements arranged in a first direction and a second direction crossing the said first direction, the estimating part estimates an estimated output value of the defective element using output values of detection elements adjacent to the defective element in the first direction and/or output values of detection elements adjacent to the defective element in the second direction, and the blurring processing part performs a blurring process for output values of detection elements used for estimating the estimated output value by the estimating part.

10 . The image processing device according to claim 9 ,
wherein the blurring processing part estimates a gap amount from a true value of an estimated output value estimated by the estimation part using output values of detection elements in rows and/or columns adjacent to a row and/or column including a defective element for which the estimated output value is estimated from among the plurality of detection element arrays in order to adjust a blurring amount or a blurring rate according to the said gap amount.

11 . A radiation imaging device comprising:
the processing device according to claim 1 , wherein a radiation source, a detector that is disposed opposite to the said radiation source and composed by arranging a plurality of detection elements, and an image generation unit that generates an image to be examined based on output values of the respective detection elements of the detector are provided.

12 . The radiation imaging device according to claim 11 ,
wherein the radiation imaging device is an X-ray CT apparatus.

13 . The radiation imaging device according to claim 12 ,
wherein the data correction unit performs estimation of an estimated output value by the estimating part and a blurring process by blurring processing part for a part of projection data from among a plurality of the projection data with different positions in the rotation direction of the detector and corrects all the rest of the projection data with different positions in the rotation direction by using the estimated output value estimated for the part of the projection data and a blurring amount used for the blurring process.

14 . An image processing method for generating an image using output values of the respective detection elements of a detector composed by arranging a plurality of the detection elements, including:
a step of estimating an output value of a defective element included in the detector using output values of the respective detection elements other than the defective element around the said defective element; a step of performing a blurring process for output values of the detection elements around the said defective element using an estimated output value estimated for the defective element; a step of setting a blurring amount or a blurring rate used for the said blurring process; and a step of generating the image using the estimated output value and the output values after the blurring process respectively for the defective element and the detection elements for which the blurring process is performed.

15 . The image processing method according to claim 14 , further including:
a step of determining whether or not to perform the blurring process before the step of

Assignees

• Hitachi Medical Corp

Inventors

• Konno Yasutaka

Classifications

• G06T12/10

  Image preprocessing, e.g. calibration, positioning of sources or scatter correction · CPC title

• G06T7/0012

  Biomedical image inspection · CPC title

• G06T5/002

  Physics · mapped topic

• A61B6/035

  Mechanical aspects of CT · CPC title

• A61B6/5258 Primary

  involving detection or reduction of artifacts or noise · CPC title