JP7281182B2 - X-ray CT device - Google Patents

Description

The present invention relates to a highly accurate X-ray CT apparatus.

Since the conventional X-ray CT apparatus for microstructure observation uses an image magnification system as shown in FIG. . Specifically, when the resolution is 10 μm to 100 μm, the observation area can be in the range of 100 μm square (square) to 0.5 mm square (square).

As shown in FIG. 6A, when the subject 2 is larger than the detection range of the detection means (CCD) 55, there are several ways to observe the entire subject 2 or a wider area. First, there is a method of using a medium-sized structural X-ray CT apparatus with low resolution. Secondly, as shown in FIG. 6B, the object 2 is moved and a partial work 52 within the detection range of the detection means 55 of the object 2 is observed with a plurality of partial X-ray CT images. There is a way. Thirdly, as shown in FIG. 6C, although the resolution deteriorates, the part of the workpiece 52 that is separated from the X-ray source 51 and is within the detection range is enlarged to increase the area of the object for X-ray CT. There is a method of observing with a single image.

However, there has been no X-ray CT technology capable of observing the entire image of a workpiece of about 100 mm square with a high resolution of 10 μm by any of the above methods.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an X-ray CT apparatus capable of observing an entire image of a workpiece of about 100 mm square with a high resolution of 10 μm.

An X-ray CT apparatus according to the present invention comprises a work holder that rotatably holds a work to be observed;
an X-ray source that irradiates the workpiece with X-rays;
Each CCD sensor for receiving the X-rays transmitted through the workpiece has a detection area equivalent to the detection area of each CCD sensor with respect to other adjacent CCD sensors along a first direction intersecting the direction of the X-rays. a CCD array spaced apart by a distance;
an image processing unit that processes image signals obtained by the CCD array;
Prepare.

According to the X-ray CT apparatus according to the present invention, a CCD array in which a plurality of CCD sensors are arranged at intervals along the first direction is used. X-ray CT images can be obtained that can be viewed with high resolution.

1 is a schematic diagram showing an outline of an imaging optical system of an X-ray CT apparatus according to Embodiment 1; FIG. 1B is a schematic plan view of the CCD array of FIG. 1A; FIG. FIG. 4 is a schematic plan view showing the CCD array at the [0] position before movement; It is a schematic plan view showing the CCD array at the [1] position after movement. 4 is a flowchart of an imaging method using the X-ray CT apparatus according to Embodiment 1; 3 is a schematic plan view showing the configuration of a CCD array in an X-ray CT apparatus according to Modification 1. FIG. FIG. 11 is a schematic plan view showing the configuration of a CCD array in an X-ray CT apparatus according to Modification 2; 2 is a schematic diagram showing the relationship between the target observation area and the resolution of the X-ray CT apparatus according to Embodiment 1; FIG. It is a schematic diagram showing an imaging optical system when a subject is larger than the detection range of the detection means (CCD). FIG. 4 is a schematic diagram showing a method of moving a subject and observing a partial workpiece within the subject that falls within the detection range of a detection means with a plurality of partial X-ray CT images; FIG. 3 is a schematic diagram showing a method of separating the object 2 from the X-ray source and enlarging the part of the work that falls within the detection range, enlarging the object area of X-ray CT, and observing it with one image.

<About the circumstances leading to the present invention>
As described above, when the subject 2 is larger than the detection range of the detection means (CCD) 55 as shown in FIG. 6A, X-rays that can be observed in a wide observation area with high resolution by either method of FIGS. 6B and 6C. Obtaining CT images was difficult.
As a result of examining the above problem, the present inventors considered that the limitation was caused by the configuration in which one X-ray source is detected by one CCD sensor. In order to obtain high resolution, generally, there is a method of increasing the magnification of the optical system or narrowing the pixel pitch of the CCD sensor, that is, reducing the size of one pixel. In digital cameras, etc., it is possible to increase the magnification of the former optical system, but in X-ray CT, the magnification of the optical system can only be increased by about 2 times at most. will be taken. In FIG. 5, in the "X-ray CT for smile structure", for example, a microfocus X-ray source is used, and the magnification is increased to nearly 10 times. Furthermore, in the "X-ray CT for ultrafine structures", the X-ray source focus is further miniaturized to the nano-level, and the magnification is increased to nearly 100 times. In these high-resolution X-ray CTs, high resolution is obtained by a method different from the approach of "narrowing the pixel pitch" in the present invention.
On the other hand, compared to the conventional CCD sensor for X-ray CT with a resolution of about 0.5 to 1 mm, the target resolution of this time is a CCD sensor for X-ray CT with a resolution of about 10 μm to 100 μm. In this case, since the method of increasing the magnification of the optical system as described above cannot be used, the size of one CCD sensor becomes considerably small, and the observation area is narrowed to the range of 100 μm to 0.5 mm. For this reason, it has been difficult to prepare a CCD sensor large enough to cover the entire observation area of the object 2 in consideration of cost.
Furthermore, if one small CCD sensor is moved and photographed sequentially over the entire observation area of the object 2, there is a problem that it takes a very long time, for example, about 20 hours.

Accordingly, the inventors of the present invention found that by using a CCD arrangement in which a plurality of CCD sensors are arranged at intervals along the first direction, it is possible to obtain a wider observation area than in the conventional art. Arrived. As a result, a wide observation area can be obtained, and an X-ray CT image that can be observed with high resolution can be obtained. In addition, by shifting the CCD array arranged at intervals, it is possible to perform imaging in a relatively short period of time, for example, about 4 hours.

An X-ray CT apparatus according to a first aspect includes a work holder that rotatably holds a work to be observed;
an X-ray source that irradiates the workpiece with X-rays;
Each CCD sensor for receiving the X-rays transmitted through the workpiece has a detection area equivalent to the detection area of each CCD sensor with respect to other adjacent CCD sensors along a first direction intersecting the direction of the X-rays. a CCD array spaced apart by a distance;
an image processing unit that processes image signals obtained by the CCD array;
Prepare.

In the X-ray CT apparatus according to a second aspect, in the first aspect, the CCD array is moved along the first direction by a distance equivalent to the detection area of each CCD sensor. You may further provide a part.

In the X-ray CT apparatus according to a third aspect, in the above first aspect, in the CCD array, each of the CCD sensors includes another CCD adjacent along a second direction intersecting the first direction. The sensors may be spaced apart by a distance equivalent to the detection area of each CCD sensor.

In the X-ray CT apparatus according to a fourth aspect, in the third aspect, the CCD array is arranged at a distance equivalent to the detection area of each CCD sensor along the first direction or the second direction. A movable CCD array moving unit may be further provided.

An X-ray CT apparatus according to an embodiment will be described below with reference to the accompanying drawings. In addition, the same code|symbol is attached|subjected about the substantially same member in drawing.

(Embodiment 1)
FIG. 1A is a schematic diagram showing an outline of an imaging optical system of an X-ray CT apparatus 20 according to Embodiment 1. FIG. FIG. 1B is a plan view of the CCD array 15 of FIG. 1A. 1A and 1B, for the sake of convenience, the direction in which the CCD sensors 14a to 14d are arranged is indicated as the x direction, and the direction of X-rays emitted from the X-ray source 11 to the CCD array 15 is indicated as the z direction.
This X-ray CT apparatus 20 includes a workpiece holder 13 that rotatably holds a workpiece 12 to be observed, an X-ray source 11 that irradiates the workpiece 12 with X-rays, and CCD sensors that receive X-rays that have passed through the workpiece 12. and an image processing unit 18 for processing image signals obtained by the CCD array 15 . In the CCD array 15, each CCD sensor 14a to 14d is arranged along a first direction (x direction) that intersects the X-ray direction (z direction), with respect to other adjacent CCD sensors. They are spaced apart by a distance equivalent to the detection area.
As a result, a CCD array in which a plurality of CCD sensors are arranged at intervals along the first direction is used, so that the observation area can be wider than before, and an X-ray CT image that can be observed with high resolution can be obtained. Obtainable.

The members constituting this X-ray CT apparatus 20 will be described below.

<X-ray source>
As the X-ray source 11, one used for a normal X-ray CT apparatus can be used.

<Work holder>
The work holder 13 rotatably holds the work 12 to be observed. In FIG. 1A, the workpiece 12 is held at a position where the magnification of the CCD array is approximately doubled. In addition, the position of the work holder 13 is not limited to the position of the above-described magnification, and may be provided at various magnifications. In addition, the work holder 13 rotates the work 12 by an angle of, for example, 0.5° and stops it at the time of imaging, so that the work 12 can be held rotatably by 360° as a whole. Also, if necessary, it may be held so that it can rotate more than 360 degrees. Furthermore, the workpiece 12 may be moved.

<CCD array>
The CCD array 15 has CCD sensors that receive the X-rays that have passed through the workpiece 12 . Specifically, as shown in FIG. 1B, a plurality of CCD sensors 14a to 14d are arranged along the x-direction at intervals of a distance d equivalent to the detection area of each CCD sensor. The distance d between the CCD sensors is, for example, equal to or smaller than the length of one CCD sensor in the x direction by several pixels. In this example, the CCD array 15 is composed of four CCD sensors 14a to 14d arranged one-dimensionally at intervals. That is, as shown in FIG. 1B, this CCD array 15 has a length L in the x-direction and has twice the viewing area as if the same four CCD sensors 14a-14d were arranged adjacent to each other. can be obtained. As a result, the entire workpiece 12 projected by the X-rays emitted from the X-ray source 11 can be viewed as an observation area.
As for the size of the CCD array 15, the length L is 100 mm or less. For example, if a large sensor is made, the signal is transmitted through a long signal line, and since the signal is attenuated and delayed, it is considered difficult to observe an area of 100 mm or more.

Incidentally, each of the CCD sensors 14a to 14d can be a commonly used CCD sensor. Further, it is preferable that the CCD sensors 14a to 14d have similar performances such as sensitivity and delay time. Although the CCD array 15 has a large area, it is relatively thin, less affected by scattered radiation, and easily shielded.
In addition, since the CCD array 15 has a thin imaging optical system, the rotating mechanism for the workpiece 12 for X-ray CT imaging also has a high degree of freedom in design, making it easy to realize a compact and high-performance mechanism. Become. In X-ray CT imaging, it is also important to reduce vibration as much as possible, and miniaturization of the imaging optical system is a great advantage in that it becomes easier to secure mechanical rigidity for stable imaging.

When the image is captured by the CCD array 15, the CCD sensors 14a to 14d are simultaneously captured for each angle of rotation of the workpiece 12. FIG. In this CCD array 15, since the CCD sensors 14a to 14d are arranged at intervals, the CCD array 15 is moved in the x-direction in order to pick up an image of a blank portion between the CCD sensors. .
Therefore, this X-ray CT apparatus further includes a CCD array moving unit 16 that moves the CCD array 15 in the x direction.

<CCD array moving part>
FIG. 2A is a schematic plan view showing the CCD array at the [0] position before movement. FIG. 2B is a schematic plan view showing the CCD array at position [1] after movement.
In FIG. 2A, for the CCD array 15 before movement, along the x-direction, the position of the CCD sensor 14a is "0", the position of the CCD sensor 14b is "2", the position of the CCD sensor 14c is "4", and the position of the CCD sensor 14c is "4". The position of 14d is set to "6". Also, the gaps between the CCD sensors are set to "1", "3", "5", and "7" in order.
As shown in FIG. 2B, the CCD array moving unit 16 can move the CCD array 15 in the x direction by the distance d between the CCD sensors. In FIG. 2B, the position of the CCD sensor 14a is "1", the position of the CCD sensor 14b is "3", the position of the CCD sensor 14c is "5", and the position of the CCD sensor 14d is "7". The distance m of movement in FIG. 2B preferably substantially matches the distance d of each CCD sensor.
If the position of the CCD array 15 before movement is "0" and the position after movement is "1", the CCD array moving unit 16 alternately moves the CCD array between positions "0" and "1". By doing so, a wide observation area can be obtained and high resolution can be obtained.
In addition, it is preferable that the CCD array moving unit 16 can be positioned with high accuracy.

<Image processing section>
The image signal obtained by the CCD array 15 is processed by the image processing section 18 . An X-ray CT image can thus be obtained. The image processing section 18 can be realized by a normal computer. For image signal processing, an image processing method commonly used in an X-ray CT apparatus can be used.

<Imaging method using an X-ray CT device>
FIG. 3 is a flowchart of an imaging method using the X-ray CT apparatus according to Embodiment 1. FIG.
The imaging method by this X-ray CT apparatus 20 is as follows.
(1) Set the rotation angle of the workpiece 12 (S01). In the initial state, the angle is 0°. Thereafter, the workpiece 12 is rotated by, for example, 0.5° and held. Note that the final state is 360°.
(2) Next, a transmission image of the workpiece 12 is obtained by the CCD array 15 at position "0" (S02). For example, the CCD array moving unit 16 may move the CCD array 15 to position "0" (FIG. 2A). Also, the work 12 is irradiated with X-rays from the X-ray source 11 and imaged simultaneously by the CCD sensors 14a to 14d of the CCD array 15 in parallel. A transmission image is obtained at the rotation angle thus set. In this case, only transmission images are obtained by the CCD sensors 14a to 14d arranged at intervals, and the gaps between the CCD sensors 14a to 14d are blank portions.

(3) Next, a transparent image of the workpiece 12 is obtained by the CCD array 15 at position "1" (S03). For example, CCD array 15 may be at position "1" (Fig. 2B). Also, the work 12 is irradiated with X-rays from the X-ray source 11 and imaged simultaneously by the CCD sensors 14a to 14d of the CCD array 15 in parallel. As a result, a transmission image corresponding to the blank portion in (2) above is obtained.
(4) Synthesize the transmission image at position "0" in (2) and the transmission image at position "1" in (3) to obtain continuous transmission images at the set rotation angle (S04).
(5) The workpiece 12 is rotated by a predetermined angle to reset the angle (S05). The rotation may be, for example, 0.5°.

(6) Confirm whether the rotation angle of the workpiece 12 is 360° (S06). If the rotation angle is not 360°, return to (2). If the rotation angle is 360°, the process proceeds to the next X-ray CT image processing.
(7) An X-ray CT image is obtained based on each transmitted image of the workpiece 12 at rotation angles of 0° to 360° (S07). Note that transmission images of both 0° and 360° may be obtained.
Also, in a plurality of CCD sensors, transmission image data is accumulated and 3D image reconstruction is performed in parallel. In other words, since images are captured by a plurality of CCD sensors arranged in parallel, the obtained data may be handled by a parallel processing algorithm of a multi-core personal computer. This parallel processing enables high-speed image processing of large-scale image data.

As described above, an X-ray CT image of the workpiece 12 can be obtained. In this case, for example, as shown in FIG. 5, a round or rectangular battery with a diameter of 10 cm to 20 cm or more and a height of 20 cm or more can be used for a short time of about 4 hours with an image resolution of 10 μm to 100 μm. It is possible to image the inside with

(Modification 1)
FIG. 4A is a schematic plan view showing the configuration of the CCD array 15a in the X-ray CT apparatus according to Modification 1. FIG.
As shown in FIG. 4A, the CCD array 15a in the X-ray CT apparatus according to Modification 1 is implemented in that the CCD sensors 14a to 14h are arrayed at intervals not only in the x direction but also in the y direction. It differs from the CCD arrangement in the X-ray CT apparatus according to the first embodiment. Specifically, each of the CCD sensors 14a to 14h constitutes a simple planar grating in plan view from the z direction.
In imaging of X-ray CT images using this CCD array, for one rotation angle, (1) imaging at position "0, 0", (2) position "1, 0" obtained by moving the CCD array in the x direction. ”, (3) imaging at position “0, 1” by moving the CCD array in the y direction, (4) imaging at position “1, 1” by moving the CCD array in the x and y directions It is necessary to perform imaging four times. In other words, to fill in the blank portion at the position "0, 0", three more times of imaging are required. Here, the positions of the CCD sensor 14a before and after movement are expressed as two-dimensional coordinates.
Since the CCD sensors 14a to 14h are two-dimensionally spaced apart to form the CCD array 15a, a two-dimensionally wider observation area can be obtained and a cross-sectional transmission image having a thickness can be obtained. Obtainable.

(Modification 2)
FIG. 4B is a schematic plan view showing the configuration of the CCD array 15b in the X-ray CT apparatus according to Modification 2. As shown in FIG.
In the CCD array 15b in the X-ray CT apparatus according to Modification 2, as shown in FIG. 4B, the CCD sensors 14a to 14h form a checkerboard pattern when viewed from above in the z direction. Compared to FIG. 4A, the difference is that a CCD sensor is also arranged in the center of the four CCD sensors.
In imaging of X-ray CT images using this CCD array, for one rotation angle, (1) imaging at position "0", (1) position "1" by moving the CCD array in the x direction or y direction It is necessary to perform imaging twice. It should be noted that unlike the case of FIG. 4A, a transparent image of a blank portion can be obtained by moving the CCD array in the x-direction or the y-direction.

It should be noted that the present disclosure includes appropriate combinations of any of the various embodiments and / or examples described above, and each embodiment and / or The effects of the embodiment can be obtained.

According to the X-ray CT apparatus according to the present invention, a CCD array in which a plurality of CCD sensors are arranged at intervals along the first direction is used. X-ray CT images can be obtained that can be viewed with high resolution. Therefore, it is useful for observing electrode structures and the like that require high resolution while requiring a wide observation area.

1 X-ray 2 Subject 11 X-ray source 12 Work 13 Work holders 14, 14a, 14b, 14c, 14d, 14e, 14f, 14g, 14h CCD sensors 15, 15a CCD array 16 CCD array moving section 18 Image processing section 20 X-ray CT device 51 X-ray source 52 Work 55 CCD array

Claims (2)

a work holder that rotatably holds a work to be observed;
an X-ray source that irradiates the workpiece with X-rays;
Each planar CCD sensor for receiving the X-rays transmitted through the workpiece is positioned in a first direction intersecting with the direction of the X-rays with respect to other adjacent planar CCD sensors. A CCD array spaced apart by a distance equivalent to the detection area of
an image processing unit that processes image signals obtained by the CCD array;
a CCD array moving unit capable of moving the CCD array along the first direction by a distance equivalent to the detection area of each of the planar CCD sensors;
An X-ray CT apparatus. a work holder that rotatably holds a work to be observed;
an X-ray source that irradiates the workpiece with X-rays;
Each planar CCD sensor for receiving the X-rays transmitted through the workpiece is positioned in a first direction intersecting with the direction of the X-rays with respect to other adjacent planar CCD sensors. A CCD array spaced apart by a distance equivalent to the detection area of
an image processing unit that processes image signals obtained by the CCD array;
with
In the CCD array, each planar CCD sensor has a detection area of each planar CCD sensor with respect to another adjacent planar CCD sensor along a second direction that intersects with the first direction. spaced an equal distance apart and
An X-ray CT apparatus, further comprising a CCD array moving unit capable of moving the CCD array along the first direction or the second direction by a distance equivalent to the detection area of each planar CCD sensor.

Images