X-ray CT apparatus and X-ray CT image-generating method

• US 9,508,142 B2
• Filed: 08/07/2013
• Issued: 11/29/2016
• Est. Priority Date: 08/22/2012
• Status: Active Grant

• Current Assignee: FUJIFILM Healthcare Corp. (Fujifilm Holdings Corporation)
• Original Assignee: Hitachi Medical Corporation (Hitachi, Ltd.)
• Inventors: Kojima, Shinichi, Yamakawa, Keisuke, Takahashi, Hisashi, Ueki, Hironori
• Primary Examiner(s): Alavi, Amir
• Application Number:
  US14/422,788
• Publication Number:
  US 20150221085A1
• Time in Patent Office: 1,210 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 6/03 Computed tomography [CT] echo-tomography A61B8/14
• CPC Class Codes: A61B 6/4233 using matrix detectors
• CPC Class Codes: A61B 6/5258 involving detection or reduction of artifacts or noise
• CPC Class Codes: G01N 23/046 using tomography, e.g. computed tomography [CT]
• CPC Class Codes: G06T 2207/10081 Computed x-ray tomography [CT]
• CPC Class Codes: G06T 2207/30004 Biomedical image processing
• CPC Class Codes: G06T 5/77 Retouching; Inpainting; Scratch removal
• CPC Class Codes: G06T 7/0012 Biomedical image inspection

Abstract

An X-ray detector (320), configured to have X-ray detecting elements (322) arranged in array, detects the intensity of X-rays that are radiated from the X-ray tube (311) and have passed through a subject (500). A data processing device (420) executes steps of: arranging scan data, which is based on the intensity of X-rays, in an array sequence of the X-ray detecting elements (322) or in a time sequence, to detect an anomalous scan data; associating a weight greater than “1” with scan data adjacent to the anomalous scan data, and associating a weight of “1” with other imaging data; calculating an update amount of a pixel vector that reflects these weights; and performing an iterative operation using the update amount to generate an X-ray CT image of the subject (500).

Claims

1. An X-ray CT apparatus comprising:

an X-ray generator that generates X-rays;

an X-ray detector that is configured to have multiple X-ray detecting elements arranged in array for detecting intensity of the X-rays;

a scanning control unit that transmits detection data detected by the X-ray detecting elements as scan data of a subject; and

a data processing device that obtains the scan data transmitted from the scanning control unit, and processes the obtained scan data to generate an X-ray CT image of the subject,

wherein the data processing device executes steps of;

storing the scan data obtained by the X-ray detecting elements into a storage unit in accordance with an arrangement of the X-ray detection elements in the X-ray detector, and detecting anomalous scan data among the stored scan data;

associating a weight with scan data adjacent to the anomalous scan data detected, the weight being greater than a weight associated with other scan data; and

calculating pixel data of the X-ray CT image of the subject, through iteration of an iterative operation using a projection matrix defined by data including a layout position of the X-ray generator and arrangement positions of the respective multiple X-ray detection elements, pixel data that has been set at that time, and the scan data,

wherein in the iterative operation, when calculating an update amount for the pixel data based on difference data between projection data obtained from the projection matrix and the pixel data at that time, and the scan data, the difference data is weighted with the weight associated with the scan data corresponding to the difference data.

2. The X-ray CT apparatus according to claim 1, wherein

if the anomalous scan data is caused by a failure of an X-ray detecting element of multiple X-ray detecting elements that constitute the X-ray detector,

the data processing device performs:

a step of associating a weight with scan data obtained from X-ray detecting elements adjacent to the fault X-ray detecting element, the weight being greater than a weight associated with other scan data.

3. The X-ray CT apparatus according to claim 2, wherein

the data processing device performs:

a step, when associating a weight with the scan data obtained from the X-ray detecting elements adjacent to the fault X-ray detecting element, of associating a weight, which is greater than a weight associated with the other scan data, with scan data obtained from X-ray detecting elements adjacent in the channel direction to the fault X-ray detecting element.

4. The X-ray CT apparatus according to claim 1, wherein

if the anomalous scan data is caused by an anomalous fluctuation of X-rays generated by the X-ray generator,

the data processing device performs:

a step of associating a weight with scan data obtained at a time one unit of time before and after the time when the anomalous fluctuation of X-rays has been detected, respectively, the weight being greater than a weight associated with other scan data.

5. The X-ray CT apparatus according to claim 1, wherein

the data processing device further performs:

a step of associating a weight with scan data further adjacent to the scan data adjacent to the anomalous scan data, the weight being smaller than a weight associated with scan data adjacent to the anomalous scan data but greater than a weight associated with the other scan data.

6. The X-ray CT apparatus according to claim 1, wherein

the data processing device performs:

a step of gradually decreasing a weight to be associated with scan data adjacent to the anomalous scan data, every time the iterative operation is iterated, so as to eventually equal to a weight associated with the other scan data.

7. The X-ray CT apparatus according to claim 1, wherein

the data processing device further performs:

a step of associating a weight with the anomalous scan data, the weight being greater than or equal to “

0”

but smaller than or equal to a weight associated with the other scan data.

8. A method for generating an X-ray CT image, for use in an X-ray CT apparatus including:

an X-ray generator that generates X-rays;

an X-ray detector that is configured to have multiple X-ray detecting elements arranged in array for detecting intensity of the X-rays;

a scanning control unit that transmits detection data detected by the X-ray detecting elements as scan data of a subject; and

a data processing device that obtains the scan data transmitted from the scanning control unit, and processes the obtained scan data to generate an X-ray CT image of the subject,

the method comprising steps, performed by the data processing device, of;

storing the scan data obtained by the X-ray detecting elements into a storage unit in accordance with an arrangement of the X-ray detection elements in the X-ray detector, and detecting anomalous scan data among the stored scan data;

associating a weight with scan data adjacent to the anomalous scan data detected, the weight being greater than a weight associated with other scan data; and

calculating pixel data of the X-ray CT image of the subject, through iteration of an iterative operation using a projection matrix defined by data including a layout position of the X-ray generator and arrangement positions of the respective multiple X-ray detection elements, pixel data that has been set at that time, and the scan data,

wherein in the iterative operation, when calculating an update amount for the pixel data based on difference data between projection data obtained from the projection matrix and the pixel data at that time, and the scan data, the difference data is weighted with the weight associated with the scan data corresponding to the difference data.

9. The method for generating an X-ray CT image according to claim 8, wherein if the anomalous scan data is caused by a failure of an X-ray detecting element of multiple X-ray detecting elements that constitute the X-ray detector,

the method comprises a step, performed by the data processing device, of:

associating a weight with scan data obtained from X-ray detecting elements adjacent to the fault X-ray detecting element, the weight being greater than a weight associated with other scan data.

10. The method for generating an X-ray CT image according to claim 9, wherein the method comprises a step of:

when associating a weight with the scan data obtained from the X-ray detecting elements adjacent to the fault X-ray detecting element, associating a weight, which is greater than a weight associated with the other scan data, with scan data obtained from the X-ray detecting elements adjacent in the channel direction to the fault X-ray detecting element.

11. The method for generating an X-ray CT image according to claim 8, wherein if the anomalous scan data is caused by an anomalous fluctuation of X-rays generated by the X-ray generator,

the method comprises a step of:

associating a weight with scan data obtained at a time one unit of time before and after the time when the anomalous fluctuation of X-rays has been detected, respectively, the weight being greater than a weight associated with other scan data.

12. The method for generating an X-ray CT image according to claim 8, wherein the method further comprises a step of:

associating a weight with scan data further adjacent to the scan data adjacent to the anomalous scan data, the weight being smaller than a weight associated with scan data adjacent to the anomalous scan data but greater than a weight associated with the other scan data.

13. The method for generating an X-ray CT image according to claim 8, wherein the method comprises a step of:

gradually decreasing a weight to be associated with scan data adjacent to the anomalous scan data, every time the iterative operation is iterated, so as to eventually equal to a weight associated with the other scan data.

14. The method for generating an X-ray CT image according to claim 8, wherein the method further comprises a step of:

associating a weight with the anomalous scan data, the weight being greater than or equal to “

0”

but smaller than or equal to a weight associated with the other scan data.