US-12618786-B2 - X-ray imaging apparatus

US12618786B2US 12618786 B2US12618786 B2US 12618786B2US-12618786-B2

Abstract

This X-ray imaging apparatus is equipped with an X-ray tube, a detector for detecting X-rays emitted from the X-ray tube and transmitted through the subject, and an image processing unit for generating an image based on a detection signal output from the detector. The X-ray imaging apparatus is provided with a controller configured to cause X-rays to be emitted such that the distance between the plurality of focal positions of the plurality of electron beams on the inclined surface differs as viewed from the subject's side, depending on the size of the subject, by causing a part of the plurality of electron emitters to emit electron beams.

Inventors

Ryo Fujita
Hiroki Maeda
Naoki Morimoto

Assignees

SHIMADZU CORPORATION

Dates

Publication Date: 20260505
Application Date: 20240223
Priority Date: 20230530

Claims (17)

1 . An X-ray imaging apparatus comprising: an X-ray tube including a plurality of electron emitters, a focusing unit, and a target, the plurality of electron emitters each having a plurality of electron sources for emitting electron beams, the plurality of electron emitters being arranged linearly on a substrate in each of a first direction and a second direction orthogonal to the first direction, the focusing unit being configured to focus each of a plurality of electron beams emitted separately from the plurality of electron emitters, the target having an inclined surface inclined to emit X-rays generated by each of the plurality of electron beams focused onto a plurality of separate-focal positions by the focusing unit; a detector configured to detect the X-rays emitted from the X-ray tube and transmitted through a subject; an image processing unit configured to generate an image based on a detection signal output from the detector; and a controller configured to cause X-rays to be emitted by causing a part of the plurality of electron emitters to emit electron beams, wherein electron emitters which emit electron beams among the plurality of electron emitters are configured to be changed depending on a size of the subject, so that the X-rays are emitted such that a distance between the plurality of focal positions of the plurality of electron beams on the inclined surface differs as viewed from a side of the subject depending on the size of the subject.
2 . The X-ray imaging apparatus as recited in claim 1 , wherein the controller is configured to perform control to cause at least one of a plurality of certain electron emitters arranged linearly in an irradiation direction of X-rays traveling from the inclined surface toward the subject as the first direction and a plurality of other electron emitters arranged linearly in a direction orthogonal to the irradiation direction as the second direction, as a part of the plurality of electron emitters arranged linearly in each of the first direction and the second direction, to emit electron beams, based on an irradiation pattern of the plurality of electron emitters according to the size of the subject.
3 . The X-ray imaging apparatus as recited in claim 2 , wherein, in a case of an irradiation pattern corresponding to a small inspection target subject which is small in size as the subject, the controller is configured to perform control to cause a plurality of certain electron emitters arranged adjacently to emit electron beams.
4 . The X-ray imaging apparatus as recited in claim 2 , wherein, in a case of an irradiation pattern corresponding to a large inspection target subject which is large in size as the subject, the controller is configured to perform control to cause at least one of the plurality of other electron emitters and a plurality of certain electron emitters arranged every other out of the plurality of certain electron emitters to emit electron beams.
5 . The X-ray imaging apparatus as recited in claim 2 , wherein each of the plurality of electron emitters includes: a plurality of cone-shaped electron sources arranged to form a rectangular shape or an oval shape with the irradiation direction as a longitudinal direction, as viewed from a target's side; and a gate electrode configured to generate an electric field to cause each of the plurality of cone-shaped electron sources to emit an electron.
6 . The X-ray imaging apparatus as recited in claim 5 , wherein the target is configured to rotate about a rotation center axis extending in a direction in which the focusing unit and the target are arranged, and wherein the controller is configured to perform control to cause at least one of the plurality of certain electron emitters and the plurality of other electron emitters to emit electron beams, based on the irradiation pattern, while rotating the target.
7 . The X-ray imaging apparatus as recited in claim 1 , wherein the X-ray tube further includes an X-ray transmission window through which the X-rays emitted from the target pass, and wherein the plurality of focal positions on the inclined surface is provided to be within the X-ray transmission window as viewed from the side of the subject.
8 . The X-ray imaging apparatus as recited in claim 1 , wherein the focusing unit includes a plurality of lens portions arranged to respectively face the plurality of certain electron emitters arranged in an irradiation direction of the X-rays traveling from the inclined surface toward the subject as the first direction out of the plurality of electron emitters arranged linearly in each of the first direction and the second direction.
9 . An X-ray imaging method comprising: an electron beams emitting step of emitting each of a plurality of electron beams separately from a plurality of electron emitters each having a plurality of electron sources for emitting electron beams, and being arranged linearly on a substrate in each of a first direction and a second direction orthogonal to the first direction; an electron beams focusing step of focusing each of the plurality of electron beams emitted separately from the plurality of electron emitters on an inclined surface; an X-rays emitting step of emitting X-rays generated by each of the plurality of electron beams focused onto a plurality of focal positions to a subject; an X-ray detecting step of detecting the X-rays transmitted through the subject; and an image generating step of generating an image based on a detection signal of the X-rays, wherein in the electron beams emitting step, electron emitters which emit electron beams among the plurality of electron emitters are configured to be changed depending on a size of the subject, so that the X-rays are emitted such that a distance between the plurality of focal positions of the plurality of electron beams on the inclined surface differs as viewed from a side of the subject depending on the size of the subject in the X-rays emitting step.
10 . An X-ray imaging apparatus comprising: an X-ray tube including a plurality of electron emitters, a focusing unit, and a target, the plurality of electron emitters each having a plurality of electron sources for emitting electron beams, the plurality of electron emitters being arranged linearly on a substrate in each of a first direction and a second direction orthogonal to the first direction, the focusing unit being configured to focus each of a plurality of electron beams emitted separately from the plurality of electron emitters, the target having an inclined surface inclined to emit X-rays generated by each of the plurality of electron beams focused onto a plurality of focal positions by the focusing unit; a detector configured to detect the X-rays emitted from the X-ray tube and transmitted through a subject; an image processing unit configured to generate an image based on a detection signal output from the detector; and a controller configured to cause X-rays to be emitted such that a distance between the plurality of focal positions of the plurality of electron beams on the inclined surface differs as viewed from a side of the subject, depending on a size of the subject, by causing a part of the plurality of electron emitters to emit electron beams based on an irradiation pattern depending on the size of the subject.
11 . The X-ray imaging apparatus as recited in claim 10 , wherein the controller is configured to perform control to cause at least one of a plurality of certain electron emitters arranged linearly in an irradiation direction of X-rays traveling from the inclined surface toward the subject as the first direction and a plurality of other electron emitters arranged linearly in a direction orthogonal to the irradiation direction as the second direction, as a part of the plurality of electron emitters arranged linearly in each of the first direction and the second direction, to emit electron beams, based on the irradiation pattern of the plurality of electron emitters according to the size of the subject.
12 . The X-ray imaging apparatus as recited in claim 11 , wherein, in a case of the irradiation pattern corresponding to a small inspection target subject which is small in size as the subject, the controller is configured to perform control to cause a plurality of certain electron emitters arranged adjacently to emit electron beams.
13 . The X-ray imaging apparatus as recited in claim 11 , wherein, in a case of the irradiation pattern corresponding to a large inspection target subject which is large in size as the subject, the controller is configured to perform control to cause at least one of the plurality of other electron emitters and a plurality of certain electron emitters arranged every other out of the plurality of certain electron emitters to emit electron beams.
14 . The X-ray imaging apparatus as recited in claim 11 , wherein each of the plurality of electron emitters includes: a plurality of cone-shaped electron sources arranged to form a rectangular shape or an oval shape with the irradiation direction as a longitudinal direction, as viewed from a target's side; and a gate electrode configured to generate an electric field to cause each of the plurality of cone-shaped electron sources to emit an electron.
15 . The X-ray imaging apparatus as recited in claim 14 , wherein the target is configured to rotate about a rotation center axis extending in a direction in which the focusing unit and the target are arranged, and wherein the controller is configured to perform control to cause at least one of the plurality of certain electron emitters and the plurality of other electron emitters to emit electron beams, based on the irradiation pattern, while rotating the target.
16 . The X-ray imaging apparatus as recited in claim 10 , wherein the X-ray tube further includes an X-ray transmission window through which the X-rays emitted from the target pass, and wherein the plurality of focal positions on the inclined surface is provided to be within the X-ray transmission window as viewed from the side of the subject.
17 . The X-ray imaging apparatus as recited in claim 10 , wherein the focusing unit includes a plurality of lens portions arranged to respectively face the plurality of electron emitters arranged in an irradiation direction of the X-rays traveling from the inclined surface toward the subject as the first direction out of the plurality of electron emitters arranged linearly in each of the first direction and the second direction.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The related Japanese Patent Application No. 2023-089124, entitled “X-ray Imaging Apparatus,” filed on May 30, 2023, invented by FUJITA Ryo, MAEDA Hiroki, MORIMOTO Naoki, upon which this patent application is based, is hereby incorporated by reference. BACKGROUND OF THE INVENTION Field of the Invention The present disclosure relates to an X-ray imaging apparatus. Description of the Related Art The following description sets forth the inventor's knowledge of the related art and problems therein and should not be construed as an admission of knowledge in the prior art. Conventionally, an X-ray imaging apparatus has been known. Such an X-ray imaging apparatus is disclosed, for example, in Japanese Patent No. 6295254. The above-described Japanese Patent No. 6295254 discloses an X-ray imaging system (X-ray imaging apparatus). This X-ray imaging system is provided with an imaging device (detector), an X-ray emitting device (X-ray tube), and a driver (controller). The imaging device is configured to detect the X-rays emitted from the X-ray emitting device and transmitted through a target object. Here, the X-ray imaging system generates an image of the target object based on the detection result of the imaging device. The X-ray emitter disclosed in the above-described Japanese Patent No. 6295254 includes a plurality of electron emission structures, a focusing structure, and an anode. Each of the plurality of electron emission structures described in the above-described Japanese Patent No. 6295254 has a plurality of electron sources. Each of the plurality of electron emission structures is configured to be controlled by the driver to emit electrons emitted from each of the plurality of electron sources as an electron beam toward an anode. The focusing structure is configured to focus the electron beam to a single focal position on the anode. The plurality of electron emission structures including such a configuration is arranged at a constant pitch on a substrate. The anode described in the above-described Japanese Patent No. 6295254 is configured to generate X-rays by emitted electrons. The anode is arranged at a position facing each of the plurality of electron emission structures in the irradiation direction of the electron beam. The anode extends in a direction orthogonal to the irradiation direction of the electron beam. The anode is configured to cause the X-rays generated by the irradiated electron beam to transmit the target object. Here, although not specifically described in the above-described Japanese Patent No. 6295254, in a conventional X-ray imaging system as described in Japanese Patent No. 6295254, in the case where the target object is relatively small in size, it is desirable for the focal positions of the plurality of electron beams to be closer to each other to ensure that the X-rays are incident on the small-sized target object. Further, in the case where the target object is relatively large in size, it is desirable to separate the focal positions of the plurality of electron beams from each other so that the range of the imaging device where the X-rays from one of the plurality of electron beams hits and the other range of the imaging device where the X-rays from the other electron beam hits are located away from each other. That is, in the case where the target object is relatively large in size, when the focal position of one electron beam and the focal position of the other electron beam are not distant from each other, similar ranges are irradiated with X-rays. Therefore, depending on the detection accuracy of the imaging device, X-rays may be detected in the same region of the plurality of imaging elements of the imaging device. In such a case, when reconstructing a plurality of images, a position correction is performed even though the positions of the images are aligned. This causes a positional deviation between the images, resulting in blurring of the reconstructed image. However, in the X-ray imaging system of the above-described Japanese Patent No. 6295254, when imaging a target image, the distances between the focal positions of the plurality of electron beams emitted separately from the plurality of electron emission structures remain unchanged. Therefore, in the case of an object small in size, it may not be possible to assuredly acquire an image of a target object (subject). While, in the case of an object large in size, the reconstructed image of the target object (subject) may be blurred. SUMMARY OF THE INVENTION The present disclosure has been made to solve the above-mentioned problems. One object of the present disclosure is to provide an X-ray imaging apparatus capable of assuredly capturing an image of a subject and suppressing the blurring of the subject in a reconstructed image. In order to attain the above-described object, the X-ray imaging apparatus according to one aspect of the present disclosure includes: an X-ray tube includ