Oblique view cone beam CT system

• US 20040017882A1
• Filed: 03/06/2003
• Published: 01/29/2004
• Est. Priority Date: 03/06/2002
• Status: Active Grant

• Current Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan)
• Original Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan)
• Inventors: Misawa, Masaki, Tiseanu, Ion
• Granted Patent: US 7,139,363 B2
• Time in Patent Office: Days
• US Class Current: 378/4
• CPC Class Codes: A61B 6/4441 the rigid structure being a C-arm or U-arm
• CPC Class Codes: A61B 6/505 for diagnosis of bone
• CPC Class Codes: A61B 6/51 for dentistry
• CPC Class Codes: G01N 2223/419 computed tomograph
• CPC Class Codes: G01N 23/046 using tomography, e.g. computed tomography [CT]

Abstract

An oblique-view cone-beam CT system comprising an X-ray source for irradiating an object with X-ray from an oblique direction with respect to a rotational axis of said object. A detector is provided for detecting projection images resulting from the X-ray irradiation. A computer electrically connected to the detector is provided for recording the detected projection images and reconstructing the recorded projection images to provide a 3-dimensional image.

Claims

1. An oblique-view cone-beam CT system comprising:

an X-ray source for irradiating an object with X-ray from an oblique direction with respect to a rotational axis of said object;

a detector for detecting projection images resulting from the X-ray irradiation; and

a computer electrically connected to the detector for recording the detected projection images and reconstructing the recorded projection images to provide a 3-dimensional image.

2. The oblique-view cone-beam CT system as defined in claim 1, further including:

a rotatable table for placing said object thereon.

3. The oblique-view cone-beam CT system as defined in claim 1, further including:

a swingable and vertically movable tilting frame for mounting said X-ray source and said detector thereon.

4. The oblique-view cone-beam CT system as defined in claim 2, further including:

a swingable and vertically movable tilting frame for mounting said X-ray source and said detector thereon while interposing therebetween said object placed on said rotatable table.

5. A method of obtaining images of a sample using an oblique-view cone-beam CT system comprising:

acquiring projection images by positioning a detector to allow a normal line passing through a detection-surface center of the detector to be oriented to a focal point of an X-ray source;

converting the projection images such that the normal line becomes perpendicular to the rotational axis of the sample;

multiplying the converted projection images by a weighting factor depending on the distance between the X-ray and the rotational axis of the sample and image coordinates Y, Z to produce weighted projection data;

fourier-transforming the weighted projection date with respect to the Y coordinate;

processing by a filter function in a frequency domain to perform a convolution; and

back projecting the Fourier-transformed data onto a 3-dimensional reconstruction grid.