JP3897606B2 - Computed tomography equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a computed tomography apparatus among non-destructive inspection apparatuses, and more particularly to a computed tomography apparatus in which a subject can be easily placed at the center of rotation.
[0002]
[Prior art]
In recent years, high-resolution industrial computer tomography apparatuses (hereinafter referred to as CT scanners) have been manufactured for the purpose of inspecting small electronic components or the like with high resolution.
[0003]
This conventional high-resolution CT scanner detects an X-ray beam generated from an X-ray tube and transmitted through a subject with an X-ray detector with two-dimensional spatial resolution to obtain a transmission image of the subject. It has become.
[0004]
When taking a cross-sectional image, a large number of transmission images are obtained while the subject is rotated once (hereinafter referred to as scanning).
[0005]
Data processing is performed on the multiple transmission images to obtain cross-sectional images (one or many) of the subject.
[0006]
The rotary table on which the subject is placed and rotated can be moved closer to or away from the X-ray tube, and the imaging magnification can be changed according to the size of the subject.
[0007]
The cross-sectional image field (imaging region) is a circle centered on the rotation center, and the smaller the imaging magnification, the smaller the circle.
[0008]
[Problems to be solved by the invention]
By the way, in this type of conventional high-resolution CT scanner described above, the subject is fixed on the rotary table by eye so that the subject is within the cross-sectional image field (imaging region).
[0009]
However, since the cross-sectional image field (imaging region) is small, it is difficult to fit the subject within the cross-sectional image field, and it is necessary to correct the fixed position many times.
[0010]
In particular, when the subject has an irregular shape, it is extremely difficult to fix the subject.
[0011]
An object of the present invention is to provide a computed tomography apparatus capable of easily placing a subject at the center of rotation.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, a radiation source that emits a radiation beam, a radiation detector that detects a radiation beam from the radiation source that has passed through the subject and obtains a transmission image of the subject, and a radiation beam Computed tomography for reconstructing a cross-sectional image of the subject from transmission images from multiple directions of the subject obtained by the radiation detector during rotation by the rotating means A device that moves a subject in the X direction and the Y direction along an imaging plane orthogonal to the axis of rotation on a rotation region, and a combination of movement in the X and Y directions by the moving unit. An XY movement amount calculation unit that calculates an amount for moving the subject in a direction substantially orthogonal to the direction of transmission of the radiation beam regardless of the rotation position, and moves by controlling the moving means according to the calculated amount Mechanism system And a part.
[0013]
Therefore, in the computer tomography apparatus of the invention corresponding to claim 1,
A moving means for moving the subject in the X direction and the Y direction along the imaging plane orthogonal to the rotation axis on the rotation area and a movement in the X direction and the Y direction by the moving means are combined to obtain a rotation position. Regardless of this, an XY movement amount calculation unit that calculates an amount for moving the subject in a direction substantially orthogonal to the direction of transmission of the radiation beam, and a mechanism control unit that controls and moves the moving means according to the calculated amount , With this, the operator rotates the subject while observing the transmission image, and moves the subject in a direction substantially perpendicular to the transmission direction at a rotation position that has a large amplitude when shaking on the transmission image field of view. Can be set and placed at the center of rotation.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
[0015]
FIG. 1 is a schematic diagram showing a system configuration example of a CT scanner according to the present embodiment.
[0016]
In FIG. 1, as an X-ray tube 1 as a radiation source, a microfocus X-ray tube having a focal point F of several to several tens of μm is generated, and an X-ray detector 3 as a radiation detector is used. For this, an X-ray flat panel sensor is used.
[0017]
The X-ray tube 1 and the X-ray detector 3 are arranged facing each other and supported by a shift mechanism 7.
[0018]
The subject 4 is placed on the rotary table 5 via an XY mechanism 8 that is a moving means, and is rotated along the imaging surface 19 in the X-ray beam 2 by the rotation / elevating mechanism 6 and the imaging is performed. It is raised and lowered substantially perpendicular to the surface 19.
[0019]
Further, the subject 4 is moved along the imaging surface 19 by the XY mechanism 8 on the rotary table 5, and the position of the subject 4 can be changed with respect to the rotary shaft 18.
[0020]
The rotary table 5 is moved together with the subject 4 between the X-ray tube 1 and the X-ray detector 3 by the shift mechanism 7 to change the imaging magnification.
[0021]
Transmission image data from the detector 3 is sent to the data processing unit 9, and the processing result and the like are displayed on the display unit 10.
[0022]
The mechanism control unit 11 is connected to the data processing unit 9, controls the mechanism unit according to a command from the data processing unit 9, and sends a status signal of the mechanism unit such as the rotation angle φ to the data processing unit 9.
[0023]
The mechanism control unit 11 sends a signal to the XY mechanism 8 on the rotary table 5 through the slip ring 13 to drive it.
[0024]
The data processing unit 9 and the display unit 10 are ordinary computers, and include a CPU, a memory, a disk, a keyboard, a mouse, an interface, and the like, and store software for reconstructing a cross-sectional image from a tomographic sequence and data in advance. is doing.
[0025]
The operator uses the data processing unit 9 and the display unit 10 to perform menu selection, condition setting, manual operation of the mechanism unit, start of tomography, apparatus status reading, cross-sectional image display, cross-sectional image analysis, and the like.
[0026]
The display unit 10 also displays a real-time transmission image.
[0027]
The data processing unit 9 includes an XY movement amount calculation unit 33 as a functional block in addition to a tomographic scan control unit, a reconstruction unit that creates a cross-sectional image, and the like.
[0028]
Other constituent elements include an X-ray controller 12 that controls the tube voltage and tube current of the X-ray tube 1, a high-voltage generator that is not shown, a shielding box that shields X-rays, and the like. I have.
[0029]
Here, main components related to the present embodiment are the XY mechanism 8 and the XY movement amount calculation unit 33.
[0030]
The XY mechanism 8 moves the subject 4 in the X direction and the Y direction along the plane of rotation on the rotation area.
[0031]
The XY movement amount calculation unit 33 combines the movement in the X direction and the Y direction by the XY mechanism 8 to move the subject 4 in a direction substantially orthogonal to the transmission direction of the X-ray beam 2 regardless of the rotation position. Calculate the amount for.
[0032]
Next, the operation of the CT scanner configured as described above according to the present embodiment will be described.
[0033]
In FIG. 1, when obtaining a transmission image, the operator places the subject 4 on the XY mechanism 8, sets the tube voltage and the tube current by the X-ray control unit 12, turns on the X-ray, and displays the transmission image. Display on the unit 10.
[0034]
The operator moves the subject 4 up and down by the rotation / lifting mechanism 6 while observing the transmission image displayed on the display unit 10, and aligns the examination surface with the imaging surface 19.
[0035]
Here, the position of the imaging surface 19 is measured in advance and displayed on the screen.
[0036]
Next, while observing the transmission image displayed on the display unit 10, the subject 9 is rotated and stopped at a rotation position where a large amplitude is obtained when the rotation swings left and right on the transmission image field (imaging region). Then, a movement command Δt toward the center of the amplitude along the screen is output (jog operation).
[0037]
This movement command is input with a keyboard or a mouse.
[0038]
As shown in the geometric diagram of FIG. 2, the XY movement amount calculation unit 33 uses the rotation angle φ,
ΔX = Δt · cos (φ)
ΔY = Δt · sin (φ)
The amount of movement in the X and Y directions is calculated according to the following formula.
[0039]
Then, a command is issued to the mechanism control unit 11 to move in a direction along the transmission image screen, that is, a direction substantially orthogonal to the transmission direction of the X-ray beam 2.
[0040]
In FIG. 2, F indicates the focal point of the X-ray beam 2.
[0041]
The subject 4 can be set at the center of rotation C by repeating the rotation and movement as described above.
[0042]
When the subject 4 is indefinite, the above alignment is performed by paying attention to the position of the imaging surface 19.
[0043]
Next, scanning is performed in accordance with the photographing magnification.
[0044]
When the tube voltage, the tube current, the integration time, and the number of views are set and scanning is started, the rotary table 5 is rotated, and a transmission image is collected by the data processing unit 9 (scan control unit 30 thereof) during this time. From the transmission data for the number of views obtained in the ° direction, the reconstruction unit reconstructs the first cross-sectional image at the position of the imaging surface 19 and displays it on the display unit 10.
[0045]
As described above, in the CT scanner according to the present embodiment, the subject 4 can be easily placed on the rotary table 5 so as to be aligned with the center of rotation.
[0046]
(Other embodiments)
In addition, this invention is not limited to the said embodiment, In the implementation stage, it can change and implement variously in the range which does not deviate from the summary.
In the above-described embodiment, the case where an X-ray flat panel sensor is used as the X-ray detector 3 has been described. However, the present invention is not limited to this. For example, an X-ray II (image intensifier) and a television are used. Any one having a two-dimensional resolution, such as a combination with a camera, can be applied.
[0047]
Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements.
For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem (at least one) described in the column of the problem to be solved by the invention can be solved, and the effect of the invention can be solved. When (at least one of) the effects described in the column can be obtained, a configuration in which this configuration requirement is deleted can be extracted as an invention.
[0048]
【The invention's effect】
As described above, according to the computed tomography apparatus of the present invention, the subject can be easily placed at the center of rotation.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an embodiment of a CT scanner according to the present invention.
FIG. 2 is a geometric diagram for explaining the operation in the CT scanner of the same embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... X-ray tube 2 ... X-ray beam 3 ... X-ray detector 4 ... Subject 5 ... Rotary table 6 ... Rotation / lifting mechanism 7 ... Shift mechanism 8 ... XY mechanism 9 ... Data processing part 10 ... Display part 11 ... Mechanism Control unit 12 X-ray control unit 13 Slip ring 18 Rotating shaft 19 Imaging plane 33 XY movement amount calculation unit C Center of rotation F Focus of X-ray beam 2

Claims (1)

A radiation source emitting a radiation beam;
A radiation detector that detects a radiation beam from the radiation source that has passed through the subject to obtain a transmission image of the subject; and
Rotation means for relatively rotating the subject in the radiation beam,
A computed tomography apparatus for reconstructing a cross-sectional image of the subject from transmission images from multiple directions of the subject obtained by the radiation detector during rotation by the rotating means,
Moving means for moving the subject in the X direction and the Y direction along an imaging plane orthogonal to the rotation axis on the rotation region;
XY movement for calculating an amount for moving the subject in a direction substantially perpendicular to the direction of transmission of the radiation beam regardless of the position of the rotation by combining movement in the X direction and Y direction by the moving means. A quantity calculator ,
A mechanism control unit for controlling and moving the moving means according to the calculated amount;
A computer tomography apparatus comprising:

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