X-ray imaging apparatus

• US 7,620,141 B2
• Filed: 01/23/2007
• Issued: 11/17/2009
• Est. Priority Date: 01/24/2006
• Status: Expired due to Fees

• Current Assignee: Shimadzu Corporation
• Original Assignee: Shimadzu Corporation
• Inventors: Gotoh, Keiichi
• Primary Examiner(s): Kiknadze; Irakli
• Application Number:
  US12/161,949
• Publication Number:
  US 20090010380A1
• Time in Patent Office: 1,029 Days
• Field of Search: 378/5, 378/8, 378/9, 378/19, 378/62, 378 988- 9812
• US Class Current: 378/5
• CPC Class Codes: A61B 6/032 Transmission computed tomography [CT]
• CPC Class Codes: A61B 6/4035 the source being combined with a filter or grating
• CPC Class Codes: A61B 6/4042 K-edge filters
• CPC Class Codes: A61B 6/4441 the rigid structure being a C-arm or U-arm
• CPC Class Codes: A61B 6/466 adapted to display 3D data
• CPC Class Codes: A61B 6/481 involving the use of contrast agents
• CPC Class Codes: A61B 6/482 involving multiple energy imaging
• CPC Class Codes: A61B 6/504 for diagnosis of blood vessels, e.g. by angiography
• CPC Class Codes: A61B 6/5264 due to motion
• CPC Class Codes: G06T 11/005 Specific pre-processing for tomographic reconstruction, e.g. calibration, source positioning, rebinning, scatter correction, retrospective gating
• CPC Class Codes: G06T 2211/412 Dynamic

Abstract

The present invention relates to an X-ray imaging apparatus using a technique for preventing artifacts appearing in 3D X-ray images. The technique involves subtraction images obtained by an energy subtraction unit serving as the basis for a 3D reconstruction process for acquiring a 3D X-ray image selectively showing a site of interest in a patient. The technique also involves an image subtraction process carried out by the energy subtraction unit according to weights set by a weight setter which selects only the site of interest in the patient, and eliminates soft tissue forming a background around the site of interest. As a result, even if body motion occurs with the soft tissue forming the background around the site of interest of the patient while subtraction images are acquired one after another by the energy subtraction unit, the body motion in the soft tissue of the patient never appears as artifacts on the subtraction images, or on a 3D X-ray image acquired on the basis of the subtraction images.

Claims

1. An X-ray imaging apparatus characterized by comprising (A) an X-ray beam emitting device for emitting X-ray beams to an object under examination to be radiographed;

(B) a two-dimensional X-ray detecting device for detecting transmitted X-ray images of the object under examination produced by emission of the X-ray beams to the object under examination, and outputting X-ray detection signals in real time;

(C) a revolution device for revolving the X-ray beam emitting device and the two-dimensional X-ray detecting device about the object under examination as opposed to each other with the object under examination in between;

(D) an X-ray energy switching control device for performing X-ray energy switching control to switch the X-ray beams emitted from the X-ray beam emitting device alternately to high energy X-ray beams of high energy and to low energy X-ray beams of low energy;

(E) a high energy image acquiring device for acquiring high energy X-ray photo images based on X-ray detection signals outputted from the two-dimensional X-ray detecting device as a result of emission of the high energy X-ray beams;

(F) a low energy image acquiring device for acquiring low energy X-ray photo images based on X-ray detection signals outputted from the two-dimensional X-ray detecting device as a result of emission of the low energy X-ray beams;

(J) a 3D reconstruction device for carrying out a 3D reconstruction process based on the high energy X-ray photo images to acquire a 3D X-ray image of high energy X-ray radiography, and a 3D reconstruction process based on the low energy X-ray photo images to acquire a 3D X-ray image of low energy X-ray radiography;

(K) a weight setting device for setting weights suitable for selecting a site of interest in the object under examination with respect to the 3D X-ray image of high energy X-ray radiography and 3D X-ray image of low energy X-ray radiography; and

(L) an energy difference using subtraction device for acquiring a 3D subtraction image through an image subtraction process carried out, according to the weights set by the weight setting device, on the 3D X-ray image of high energy X-ray radiography and 3D X-ray image of low energy X-ray radiography.

2. An X-ray imaging apparatus as defined in claim 1, comprising a contrast medium using subtraction device for acquiring a subtraction image selecting a contrast medium injected site through an image subtraction process carried out on images of the object under examination before a contrast medium is injected and on images of the object under examination after the contrast medium is injected.

3. An X-ray imaging apparatus as defined in claim 2, wherein the contrast medium using subtraction device carries out the image subtraction process on the subtraction images, acquired by the energy subtraction device, of the object under examination before and after the contrast medium is injected, respectively, and the 3D reconstruction device carries out the 3D reconstruction process using the subtraction images acquired by the contrast medium using subtraction device.

4. An X-ray imaging apparatus as defined in claim 1, wherein the X-ray beam emitting device and the two-dimensional X-ray detecting device are attached separately to one end and the other end of a C-shaped arm to be opposed to each other.

5. An X-ray imaging apparatus as defined in claim 4, wherein a revolution device revolves the X-ray beam emitting device and the two-dimensional X-ray detecting device through at least 180 degrees about the object under examination.

6. An X-ray imaging apparatus as defined in claim 5, wherein the revolution device drives the X-ray beam emitting device and the two-dimensional X-ray detecting device for accelerated revolution, uniform speed revolution and decelerated revolution in order, the X-ray beams being emitted while the X-ray beam emitting device and the two-dimensional X-ray detecting device are driven for the uniform speed revolution.

7. An X-ray imaging apparatus as defined in claim 1, wherein the X-ray energy switching control device applies a high voltage to the X-ray beam emitting device to emit the high energy X-ray beams of high energy, and applies a low voltage to the X-ray beam emitting device to emit the low energy X-ray beams of low energy.

8. An X-ray imaging apparatus as defined in claim 1, wherein the X-ray energy switching control device causes the X-ray beams emitted from the X-ray beam emitting device to pass through a low energy absorbing member, thereby to emit the high energy X-ray beams of high energy, and causes the X-ray beams emitted from the X-ray beam emitting device to pass through a high energy absorbing member, thereby to emit the low energy X-ray beams of low energy.