KR101257165B1 - Ct device and image pickup method of ct device - Google Patents

Abstract

Provided is a CT device that obtains a cross-sectional image of an object having a layered structure in a short tomography time.
The layered surface of the layered structure of the subject 5 to be photographed is placed on the table 4 so as to intersect the tomography imaging surface, and the radiation is directed around the radiation optical axis along the tomography plane toward the subject 5 to be photographed. The radiation source 1 to radiate, the radiation detector 3 which detects the radiation 2 which permeate | transmitted the test object 5, and outputs it as a transmission image, and the rotation which rotates the table 4 and the radiation 2 relatively By controlling the means 7, the rotation means 7, and the radiation detection means 3, a plurality of transmission images are preferentially given a rotation angle at which the layer surface of the object 5 is parallel to the optical axis of the radiation 2. Scan control means 9c which introduces and stores as scan data and scans, and reconstruction means 9d which reconstructs at least one cross-sectional image parallel to the tomography surface of the subject 5 from this scan data. Have

Description

How to photograph CT device and CT device {CT DEVICE AND IMAGE PICKUP METHOD OF CT DEVICE}

The present invention relates to a computed tomography apparatus (hereinafter referred to as a CT (Computed Tomography) apparatus) for photographing a cross-sectional image of a subject.

In recent years, the demand for secondary batteries, such as a lithium ion battery and a nickel-metal hydride battery, is expanded by the development of mobile devices, such as a mobile telephone, and the practical use of an electric vehicle. As a result, the importance of battery inspection for supplying safe and reliable batteries that do not cause shorts or ignition is increasing. As this battery test | inspection, the method of taking the cross-sectional image of the to-be-tested object which has a layered structure, and inspecting is known.

First, the conceptual diagram (cross section) of the battery 90 which is a subject under test is shown. This figure is sectional drawing which shows the outline of structures, such as a lithium ion battery, a nickel hydride battery, and a nickel card battery. In the case 91, the positive electrode plate 92 and the negative electrode plate 93 are wound and stored several times through a separator (not shown), and the voids are filled with the electrolyte solution 94. For example, the pitch (positive plate-positive plate) of the layer is about 0.3 mm, the number of turns is several tens of times, and the dimension of the whole cross section is about 30 mm x 120 mm.

In the inspection of the battery using the CT apparatus, in order to inspect the battery of such a structure, the cross-sectional image as shown in FIG. The wrinkles of the layers and the disturbance of the intervals between layers can be confirmed, and the change over time when the battery is used can be inspected by tracking.

It describes about the conventional CT apparatus used for the test of this battery. In a conventional CT device, a CT device called a RR (Rotate Rotate) method (third generation method) which performs rotation only, irradiates radiation (X-ray) generated from a radiation source toward a subject, and examines the subject. The radiation detector rotates relatively to the radiation with a rotation axis intersecting with the direction of the optical axis, and transmits radiation transmitted from the subject at every predetermined rotation angle interval in one detected rotation to a radiation detector having a plurality of detection channels in one or two dimensions. It detects by this and acquires (tomographic image) the cross-sectional image of a subject to 3D data from this detector output.

As a prior art, the structure of the CT apparatus described in patent document 1 in FIG. 8 is shown. (A) is a top view, (b) is a front view. In the figure, the X-ray tube 101 and the X-ray detector 103 for detecting the pyramidal X-ray beam 102 generated here with two-dimensional resolution are disposed to face each other, and the X-ray beam ( The transmission image (transmission data) of the subject 105 mounted on the table 104 is obtained so as to enter 102.

The table 104 is disposed on the XY mechanism 106, and the XY mechanism 106 is disposed on the rotation / elevation mechanism 107. When photographing the cross-sectional image of the subject 105, a transmission image is obtained in many directions while rotating the table 104 by the rotation / elevation mechanism 107 about the rotation axis RA (hereinafter referred to as scan). . A large number of transmission images obtained by this scan can be processed by the control processing unit 108 to obtain a cross-sectional image (one to many sheets) of the object 105. Here, the XY mechanism 106 is used to move the table 104 in the plane orthogonal to the rotation axis RA with respect to the rotation axis RA, and to adjust the position so that the interested portion 105a of the object 105 is on the rotation axis RA. do. In addition, the rotation axis RA and the detector 103 are moved closer to or away from the X-ray tube 101 by the shift mechanism 109, so that the imaging magnification (= FDD / FCD) can be changed according to the purpose.

On the other hand, in the case of a pyramidal X-ray beam, the method described in the nonpatent literature 1 is used for the method of a reconstruction process normally. This method is a kind of filter correction back projection method (FBP (Filtered Back Projection) method), and is three-dimensionally back projection. The cross-sectional field of view (or referred to as scan area) 110 shown in FIG. 8 is included in the X-ray beam 102 which is always detected by the detector 103 while the table 104 is rotated one rotation about the rotation axis RA. It is defined as an area. The cross-sectional field of view 110 is an area of a substantially cylindrical shape having the axis of rotation RA as an axis, and is a region capable of reconstructing the cross-sectional image without difficulty. In addition, when the photographing magnification is increased in cross section, the diameter and height decrease in inverse proportion to this.

By the way, as described in patent document 1, the method of tomographically enlarging a part of the to-be-tested object 105 is known (henceforth ROI (Region of Interest) scan). In this tomography, as shown in FIG. 8A, the cross-sectional field of view 110 is made small, and the shift mechanism so that the region of interest 105a of the subject 105 converges accurately to the cross-sectional field of view 110. 109 and the XY mechanism 106 are positioned. As a result, an enlarged cross-sectional image of a high spatial resolution of the interested portion 105a can be obtained. In addition, with the conventional CT apparatus, it is possible to perform cross-sectional imaging of a portion of interest of the layer structure of the battery 90 with high resolution, for example, by ROI scanning.

Japanese Patent Publication No. 2002-310943

L.A.Feldkamp, L.C.Davis and J.W.Kress, Practical cone-beam algorithm, J.Opt, Soc.Am.A / Vol.1, No.6 / June 1984

However, when tomographic imaging a subject having a layered structure such as a battery, it is necessary to reduce the rotation angle interval (sampling pitch in the rotational direction) for detecting the transmission image during rotation.

The case of the battery of FIG. 7 will be described as an example. In the cross-section, in the linear part of an electrode layer, each electrode plate and separator are about 0.1 mm in thickness, and are very thin and long about 100 mm in length. In the case of such an elongated electrode plate, when the rotation angle interval is large, a linear counterfeit image occurs in the direction along the electrode plate and damages the resolution in the thickness direction (resolution for the layer structure). In this case, it is necessary to make the rotation angle interval which detects a transmission image in one rotation fine about 0.06 degree, and the number of 360 degree views (the number of transmission image photographs in one rotation) becomes 6000.

As described above, in the conventional CT device, it is necessary to increase the number of views in order to ensure the resolution in the direction orthogonal to the layer of the layered object under test, and there is a problem that the tomography time is long.

This invention is made | formed in view of the said situation, The objective is to provide the CT apparatus which obtains the cross-sectional image of the to-be-tested object which has a layered structure in short tomography time.

In order to achieve the above object, the invention described in claim 1 is a CT device for photographing a cross-sectional image of a subject having a layered structure, wherein the subject is placed on a table so that the layered surface of the layered structure to be photographed intersects the tomographic plane. A radiation source for emitting radiation about a radiation optical axis along the tomography plane, radiation detection means for detecting and outputting the radiation transmitted through the subject as a transmission image, and a rotation axis orthogonal to the tomography plane Scans a plurality of transmission images preferentially by a rotation means for relatively rotating a table and the radiation, and a rotational angle at which the layer plane approaches parallel to the radiation optical axis while the rotation is controlled by controlling the rotation means and the radiation detection means. Scan control means for performing a preferential scan to be introduced and stored as data; And in that a base from the group of scanning of the data with a reconstruction means for reconstructing the at least one piece of the cross section parallel to the tomographic surface of the subject.

According to this configuration, the scanning angle is scanned preferentially (detection of the transmission image with a high frequency or limited angle) at which the layer surface of the layer structure of the subject to be imaged is parallel to the radiation optical axis. Since the cross-sectional image of the subject is reconstructed, the radiation optical axis that does not contribute to the resolution of the layer structure on the cross-sectional image does not give priority to the transmission image detection of the rotation range that crosses the layer surface at a large angle as compared to the scan of one rotation, so that it is perpendicular to the layer surface. The time required for scanning can be shortened while maintaining the resolution in the direction of the direction. In addition, the time required for cross-sectional reconstruction can also be shortened.

In order to achieve the above object, the invention according to claim 2 is the CT device according to claim 1, wherein the scan control means is a preferential scan, centering on a first rotational position in which the layer plane is parallel to the radiation optical axis. It is a summary to perform the 1st scan which introduces and stores as a 1st scan data the several transmission image detected while making the said rotation in the 1st rotation angle range containing the said 1st rotation position within +/- 60 degree which is said do.

With this configuration, a first scan is performed in a limited first rotational angle range including a rotational position at which the layer surface of the layered structure to be photographed of the subject is parallel to the radiation optical axis, thereby detecting the first detected in the first rotational angle range. Since the cross-sectional image of the subject is reconstructed from the scan data, compared to the scanning of one rotation, the transmission of the image of the rotation range in which the radiation optical axis which does not contribute to the resolution of the layer structure on the cross-sectional image at a large angle to the layer surface is omitted. The time required for scanning can be shortened while maintaining the resolution in the orthogonal direction. In addition, the time required for cross-sectional reconstruction can also be shortened.

In order to achieve the above object, the invention according to claim 3 is the CT device according to claim 2, wherein the scan control means is configured as a second scan position that is 180 ° different from the first rotation position as the preferential scan. It is essential to perform a second scan in which a plurality of transmitted images detected while performing the rotation in a second rotation angle range including the second rotation position within a center of ± 60 ° as a center are introduced and stored as second scan data. Shall be.

By this structure, similarly to the invention of Claim 2, compared with the scan of 1 rotation, the radiation plane which does not contribute to the resolution of the layer structure of a cross-sectional image omits the transmission image detection of the rotation range which crosses a layer plane at a large angle, and layer surface. The time required for scanning can be shortened while maintaining the resolution in the direction orthogonal to. In addition, the time required for cross-sectional reconstruction can also be shortened.

In order to achieve the above object, the invention according to claim 4 is the CT device according to claim 2, wherein the scan control means detects a plurality of transmission images at each first rotation angle interval in the first scan, The scan control means is detected for each of the third rotation angle intervals larger than the first rotation angle interval while the rotation is performed in the third rotation angle range including the at least a portion outside the first rotation angle range as the preferential scan. It is a summary to perform a 3rd scan which introduces and stores a plurality of transmitted images as 3rd scan data.

In order to achieve the said objective, invention of Claim 5 is the CT apparatus of Claim 3 WHEREIN: The said scan control means detects the several transmission image for every 1st rotation angle interval in the said 1st scan, In the second scan, a plurality of transmission images are detected at every second rotation angle interval, and the scan control means includes, as the preferential scan, at least a portion outside the first rotation angle range and the second rotation angle range. The plurality of transmission images detected for each of the third rotation angle intervals greater than either one of the first rotation angle interval and the second rotation angle interval while the rotation is performed in the third rotation angle range to be introduced are stored as third scan data. A summary scan is performed.

By the structure of Claim 4 and 5, compared with the normal one rotation scan, the rotational image detection of the transmission range of the rotation range which a radiation optical axis which does not contribute to the resolution of the layer structure on a cross section at a large angle to a layer surface is roughly rotated. By angular intervals, the time required for scanning and the time required for cross-sectional reconstruction can be shortened while maintaining the resolution in the direction orthogonal to the layer surface. You can make it appear.

In order to achieve the above object, the invention according to claim 6 is a photographing method of a CT device for photographing a cross-sectional image of a subject having a layered structure, wherein the layered surface of the layered structure to be photographed is placed on a table so as to intersect the tomographic plane. A radiation source that radiates radiation around a radiation optical axis along the tomography plane toward the subject, radiation detection means for detecting and outputting the radiation transmitted through the subject as a transmission image, and a rotation axis orthogonal to the tomography plane Rotation means for relatively rotating the table and the radiation, and a plurality of transmitted images detected while controlling the rotation means and the radiation detection means to rotate the rotation within a predetermined rotation angle range are introduced and stored as scan data. Scan control means for performing a scan and the stored scan data In a CT apparatus having reconstruction means for reconstructing a cross section of a subject, the process of specifying a first rotational position at which the layer plane is parallel to the radiation optical axis, and preferentially giving a rotational angle close to the first rotational position while the rotation is performed. And a step of performing a preferential scan for introducing and storing a plurality of transmission images as scan data, and reconstructing at least one cross-sectional image parallel to the tomography surface of the subject from the scan data. Shall be.

In this way, the same effects as in the invention described in claim 1 can be obtained.

In order to achieve the above object, the invention described in claim 7 is the imaging method of the CT device according to claim 6, wherein the preferential scanning is within ± 60 ° centering on the first rotational position and the first rotation. A scan of a first rotational angle range including a position, or a second rotational angle range that includes the second rotational position within ± 60 ° about a second rotational position that is 180 ° different from the first rotational position It is a summary that it is a scan which added more scans of.

In this way, the same effects as in the inventions described in Claims 2 and 3 can be obtained.

According to this invention, the CT apparatus which obtains the cross-sectional image of the to-be-tested object which has a layered structure in a short tomography time can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic diagram which shows the structure of the CT apparatus which concerns on 1st Embodiment of this invention ((a) top view, (b) front view).
2 is a flowchart of tomography according to the first embodiment of the present invention.
FIG. 3 is a view showing a loaded state of a table of a battery according to the first embodiment of the present invention (plan view). FIG.
4 is an example of a rotation angle range of a scan according to the first embodiment of the present invention.
5 is an example of a rotation angle range of a scan according to Modification Example 3 of the first embodiment of the present invention.
6 is an example of a rotation angle range of a scan according to a modification 5 of the first embodiment of the present invention.
7 is a conceptual view (sectional view) of a battery 90 as a test object.
8 is a schematic view showing the structure of a conventional CT device ((a) plan view, (b) front view).

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to FIGS. 1-6 as an Example of this invention.

(Configuration of First Embodiment of the Present Invention)

EMBODIMENT OF THE INVENTION Hereinafter, the structure of 1st Embodiment of this invention is demonstrated with reference to FIG. 1: is a schematic diagram ((a) plan view, (b) front view) which shows the structure of the CT apparatus which concerns on 1st Embodiment of this invention. As shown in FIG. 1, a pyramidal X centering on an X-ray tube (radiation source) 1 and an optical axis (radiation optical axis) L which is a part of X-rays radiated from the X-ray focal point F of the X-ray tube 1 X-ray detectors (radiation detection means) 3 for detecting the ray beams (radiation) 2 with two-dimensional resolution are disposed to face each other, and are placed on the table 4 to enter the X-ray beams 2. The X-ray beam 2 passing through the inspected object 5 is detected by the X-ray detector 3 and output as a transmission image (transmission data).

The table 4 is arrange | positioned on the XY mechanism 6, and the XY mechanism 6 is arrange | positioned on the rotation / elevation mechanism (rotation means) 7. Table 4 rotates vertically with X-ray beam 2 by rotation / elevation mechanism 7 (intersects with X-ray beam 2, and may be substantially perpendicular to the direction of optical axis L). While being rotated with respect to RA, it is z-moved (ascended) in the z direction parallel to the axis of rotation RA. The XY mechanism 6 XY moves the table 4 in the XY plane orthogonal to the rotation axis RA with respect to the rotation axis RA and the X-ray beam 2.

Tomographic plane TP is defined as a plane passing through X-ray focal point F and perpendicular to rotation axis RA, and optical axis L is on tomographic plane TP. In addition, by the shift mechanism (shooting magnification setting means) 8, the rotational axis RA (and the table 4) and the X-ray detector 3 can be moved closer to or farther from the X-ray tube 1, so that the X-ray Shooting distance FCD (Focus to rotation Center Distance) between X-ray focus F of tube 1 and rotation axis RA, and detection distance FDD (Focus) between X-ray focus F and detection surface 3a of X-ray detector 3 to Detector Distance).

Here, the XY mechanism 6 is used to adjust the position so that the point of interest of the subject 5 is on the axis of rotation RA, the shift mechanism 8 is used to change the imaging magnification (= FDD / FCD) according to the purpose, The z-movement of the rotation / elevation mechanism 7 is used to match the region of interest of the subject 5 to the height of the X-ray beam 2. In addition, the rotation of the rotation / elevation mechanism 7 is used to rotate the inspected object 5 with respect to the X-ray beam 2 when photographing a cross-sectional image to obtain a transmission image in a number of directions.

The cross-sectional field of view (or referred to as a scan area) 10 shown in FIG. 1 is defined as an area included in the X-ray beam 2 that is always measured during one revolution. The cross-sectional field of view 10 is an area of a substantially cylindrical shape with the axis of rotation RA as an axis, and is a region where the cross-sectional image can be reconstructed without difficulty. In addition to this component, a control processing unit that controls each mechanism (XY mechanism 6, rotation / elevation mechanism 7, shift mechanism 8), and also processes transmission data from the X-ray detector 3 (9), the display part 9a which displays a process result, etc., the X-ray control part (not shown) which controls the X-ray tube 1, etc. are mentioned.

The control processing unit 9 is composed of a CPU, a memory, a disk (nonvolatile memory), a display unit 9a, an input unit (such as a keyboard or a mouse) 9b, a mechanism control board, an interface, and the like by a normal computer.

The control processing unit 9 receives signals (encoder pulses, etc.) of the operation positions of the mechanisms 6, 7 and 8 by the instrument control board, and controls the mechanisms 6, 7 and 8 to position the subject. In addition to performing alignment, scanning (tomographic scanning), etc., a command pulse for collecting transmission data and the like are sent to the X-ray detector 3. Moreover, the encoder (not shown) is provided in each mechanism part 6,7,8, The XY movement position X, Y by the XY mechanism 6 of the table 4, and the z movement by the rotation / lifting mechanism 7 are shown. Position z, rotation angle phi, and FCD and FDD by the shift mechanism 8 are read and sent to the control processing unit 9, respectively.

In addition, the control processing unit 9 collects, stores, and reconstructs the transmission data from the X-ray detector 3 at the time of tomography, to determine the cross-sectional image of one or more sheets of the object parallel to the tomography surface. It creates and displays it on the display part 9a. In addition, the control processing unit 9 commands an X-ray control unit (not shown), specifies a tube voltage and a tube current, and instructs radiation and stop of X-rays. Tube voltage and tube current can be changed in accordance with the subject.

As shown in Fig. 1, the control processing unit 9 is a function block in which the CPU reads software and functions, and introduces and stores a plurality of transmitted images detected while rotating the table 4 in a predetermined range as scan data. And a reconstruction section (reconstruction means) 9d for creating a cross-sectional image using scan data, and the like.

(Operation of the First Embodiment)

An operation of the first embodiment having the above-described configuration will be described with reference to FIGS. 7, 2 to 4 by taking an example in which the battery 90 is photographed as the object 5.

7 shows a conceptual view (cross section) of the battery 90 as a test subject. This figure is sectional drawing which shows the outline of structures, such as a lithium ion battery, a nickel hydride battery, and a nickel card battery. In the case 91, the positive electrode plate 92 and the negative electrode plate 93 are wound and stored several times through a separator (not shown), and the voids are filled with the electrolyte solution 94. For example, the pitch (positive plate-positive plate) of the layer is about 0.3 mm, the number of turns is several tens of times, and the dimension of the whole cross section is about 30 mm x 120 mm.

2 is a flowchart of tomography according to the first embodiment, and as a process of tomography according to the present example,

(1) step of loading batteries

(2) Steps to set shooting conditions

(3) Step to scan

(4) Reconstruction Step

Each process is provided. Hereinafter, each process will be described.

(1) step of loading batteries

As shown in FIG. 2, in step S1, the operator loads the battery 90 on the table 4 as follows. Fig. 3 is a view showing a loaded state of a table of a battery (top view). First, the rotation angle of the table 4 is reset to 0 ° (first rotational position), and then the layer surface 12 of the layer structure in the region (ROI: region of interest) 11 to be photographed of the battery 90 is obtained. ) Crosses the tomography surface TP (substantially orthogonally), and the layer surface 12 is loaded so as to be parallel to the optical axis L.

(2) Steps to set shooting conditions

Next, a shooting condition is set in step S2. These shooting conditions include geometric conditions, X-ray conditions, scan conditions, reconstruction conditions, and the like. As the geometric condition setting, a command is input from the input unit 9b, and the XY mechanism 6 is controlled so that the region 11 to be photographed is roughly the rotation axis RA image, and the region 11 to be photographed is in cross section. The shift mechanism 8 is controlled to coincide with the visual field 10 to set the photographing magnification. In addition, the rotation elevating mechanism 7 is controlled from the input unit 9b to adjust the height of the region 11 to be photographed to the tomographic plane TP.

As the X-ray condition setting, a tube voltage and a tube current suitable for the subject are set. In setting the scanning conditions, the layer surface 12 is configured to detect the transmission image preferentially (at a high frequency or at an angle limitation) at a rotation angle close to parallel to the optical axis L. Specifically, as the scan condition setting, the rotation angle range (first rotation angle range) is within a range of ± 60 ° centered on 0 ° (first rotational position) and includes 0 ° as a continuous range (120 ° or less). ) Is set as the scan range. For example, FIG. 4 is an example of the rotation angle range of a scan, and sets the range of 45 degree centering on 0 degree here as a rotation angle range.

As the scan condition setting, the rotation angle interval (for example, 0.075 °) for detecting the transmission image, the integral frame number (for example, 5), etc., of one transmission phase are set. As the reconstruction condition, the number of sections on the cross section and the interval (cross section position relative to the tomography plane TP) and the like in the direction of the rotation axis thereof are set.

(3) Step to scan

After step S2, a scan is performed in step S3. When the operator inputs a scan start, the scan control unit 9c controls the rotation elevating mechanism 7 and the X-ray detector 3 to rotate the table 4 (continuously or stepwise) in the set rotation angle range. A plurality of transmitted images detected for each set (first) rotation angle interval are introduced and stored as (first) scan data.

(4) Reconstruction Step

After step S3, in step S4, the reconstructing unit 9d selects, from the scan data, at least one cross-sectional image (of the set cross-sectional position) parallel to the tomography plane TP of the cross-sectional image in the cross-sectional view 10 of the battery 90. It reconstructs and displays and stores. The reconstruction is performed by the normal filter correction reverse projection method, but the difference is that the filter correction reverse projection for 360 degrees is different, whereas the filter correction reverse projection only in the data of the scanned angular range is different here (that is, not scanning). Equivalent to backprojecting zero over an angular range that does not). This completes the flow of FIG. 2.

(Effect of 1st Embodiment)

According to the first embodiment, the rotation angle of the scan (45 degrees) around the rotational position where the layer surface 12 of the layer structure in the region 11 to be imaged of the battery 90 is parallel to the optical axis L Scanning is performed in the range, and since the cross-sectional image of the battery 90 is reconstructed from the scan data detected in this rotation angle range, the optical axis L which does not contribute to the resolution of the layer structure on the cross-sectional image is compared to the scanning of one rotation. By omitting the transmission image detection of the rotation range intersecting at a great angle with 12), the time required for scanning can be shortened while maintaining the resolution in the direction orthogonal to the layer plane. In addition, the time required for cross-sectional reconstruction can also be shortened. Specifically, the scan time and the reconstruction time are approximately 1/8 since the scan performed at 360 ° should just be a 45 ° scan.

In fact, comparing {image 1: cross-sectional image taken by tomography under the conditions of the first embodiment (45 ° scan)} and {image 2: cross-sectional image taken by 360 ° scan under the same conditions}, image 1 is slightly more imaged. Although the noise was large, the resolution in the direction orthogonal to the layer surface 12 was equivalent. The noise of the image 1 is large because the amount of data in the direction along the layer plane of the optical axis L becomes half of the image 2. Therefore, when the image 1 'was imaged by doubling the number of integrated frames under the shooting conditions of the image 1, and compared, the image 1' and the image 2 became an image which is indistinguishable.

Further, according to the first embodiment, there is an effect that ring-shaped artifacts are less likely to occur as a secondary effect. In fact, when comparing the above-mentioned image 1 and image 2, in the image 2, a faint ring-shaped artifact around the rotational axis RA was confirmed, but in the image 1, it was not confirmed at all.

(Modification of the first embodiment)

In addition, this invention is not limited to the said embodiment, It can variously deform and implement in the range which does not deviate from the summary.

(Modification 1)

In 1st Embodiment, although the rotation angle range of 45 degrees scan was set centering on the rotation position which the layer surface 12 of a layer structure parallels with the optical axis L, the rotation angle range may not necessarily be 45 degrees. The layer structure of the battery 90 is inclined locally from the layer surface 12 due to winding unevenness or wrinkles. Since the transmission image from the direction within this inclination range should be obtained, what is necessary is just to set the rotation angle range so that the anticipated inclination angle range (alpha) may be included.

Precisely, the layer structure of the cell is thick in the field of view, so it rotates by an angle β from the rotational position through which X-rays pass parallel to the top layer of thickness to the rotational position through which X-rays transmit parallel to the bottom layer of thickness. It is necessary to increase the angular range. Therefore, what is necessary is just to increase by (beta) and to set it over (alpha) + (beta) as a rotation angle range. This angle β corresponds to this thick angle seen from the rough X-ray focal point F, and the value of β is the maximum at the maximum thickness (= diameter of the cross-sectional field of view 10), where β corresponds to the fan angle θo (FIG. 1). Reference). In a typical battery, the α + β does not exceed 120 °, so the rotation angle range may be set to include 0 ° within ± 60 ° (total width 120 ° or less), but in addition to the subject, it is as narrow as possible. It is possible to further increase the speed by setting. The width of the rotation angle range may be, for example, 20 °, 10 °, or a small range when the flatness of the subject is good.

(Modified example 2)

In the first embodiment, the rotation angle range of 45 ° scan is set symmetrically about the rotational position where the layer surface 12 of the layer structure is parallel to the optical axis L (usually symmetry is preferable), but not exactly symmetrical It may be good and roughly symmetrical.

(Modification 3)

In the first embodiment, the second rotational position is also within ± 60 ° about the second rotational position (180 °) that is 180 ° different from the (first) rotational position (0 °) on which the battery 90 is loaded. Set a second rotation angle range (120 ° or less), which is a continuous range including a second, and rotates the table 4 in this second rotation angle range, and transmits a plurality of transmitted images detected at every second rotation angle intervals. A second scan to be introduced and stored as scan data may be performed to reconstruct at least one cross-sectional image parallel to the tomography plane TP of the battery 90 from the first (first) scan data and the second scan data. .

FIG. 5: is an example of the rotation angle range of the scan which concerns on the modification 3, and as 2nd rotation angle range is 45 degree centering on 180 degree. In this case, as described in the first embodiment, the first scan data may be reconstructed, the second scan data may be reconstructed similarly, and both cross-sectional images may be added. Further, the second scan data may be subjected to filter correction back projection on the cross section in which the first scan data is subjected to filter correction back projection.

In addition, the second rotation angle range is not within the range of 45 ° centered on 180 ° like the first rotation angle range, but within ± 60 ° centered on 180 °, and includes the second rotation position 180 °. The rotation angle range may be sufficient. In addition, although a 2nd rotation angle interval is made the same as a 1st rotation angle interval normally, you may differ. According to the third modification, the same effects as in the first embodiment can be obtained.

Specifically, the scan time and the reconstruction time are approximately 1/4 because the scan performed at 360 ° is made of 45 ° and 45 ° scans. In fact, when comparing {Image 3: cross-sectional image taken by tomography under the conditions of the modification 3 (45 ° and 45 ° scan)} and {image 2: cross-sectional image taken by 360 ° scan under the same conditions}, the image 3 and the image 2 became the image which was indistinguishable. In addition, in image 2, a faint ring-shaped artifact around the rotational axis RA was confirmed, but in image 3, it was not confirmed at all.

(Modification 4)

In the first embodiment, the portion of the planar layer is selected as the region 11 to be photographed of the battery 90, but the layer may be curved. In this case, when the tangential direction of the layer part to be observed is set as the layer surface 12 and conditions are set, the layer part parallel to this layer surface 12 as an outline is obtained as a favorable cross-sectional shape.

(Modification 5)

In the first embodiment, when the battery 90 includes a structure other than the layered structure, it is sometimes necessary to photograph the structure so that the other structure appears to some extent on the cross section of the layered structure. In this case, in addition to the first scan (and the second scan of Variation 3) of the first embodiment, an approximate third scan having a larger rotation angle interval is applied to scan the first scan (and the second scan) and the third scan. It is possible to reconstruct the cross-sectional view of the battery 90 from the data.

The third scan includes a first rotation angle interval (either one of the second rotation angle intervals) while rotating in a third rotation angle range that includes at least a portion outside the first rotation angle range (and the second rotation angle range). The plurality of transmitted images detected at each larger third rotation angle interval are introduced and stored as third scan data.

6 is an example of the rotation angle range of the scan according to the modification 5. FIG.

The third scan may be a full scan having a rotation angle range of 360 ° or a half scan of 180 ° + fan angle θo or more and 360 ° or less, but also supplements a portion outside the first rotation angle range (and the second rotation angle range). The scan may be performed. As the rotation angle range of this replenishment scan, all the outer parts may be sufficient, a part of an outer part may overlap, and may overlap with the 1st rotation angle range (and 2nd rotation angle range).

The reconstructing unit 9d reconstructs at least one cross-sectional image parallel to the tomography surface of the subject from the first scan data, the second scan data, and the third scan data. Reconstruction is obtained by reconstructing the cross-sectional images with the first to third scan data, respectively, and adding these cross-sectional images (including weighting addition addition). Further, the first to third scan data may be continued to filter corrected reverse projection (including weighted reverse projection).

According to the modification 5, the transmission angle detection of the rotation range in which the optical axis L which does not contribute to the resolution of the layer structure on the cross section crosses the layer surface 12 at a large angle as compared with the normal one rotation scan is approximately the rotation angle interval. By shortening the time required for the scan and the time required for the cross-sectional reconstruction while maintaining the resolution in the direction orthogonal to the layer surface 12, the structure other than the layered structure on the cross-section is also somewhat satisfactory. To make it appear.

(Modification 6)

In the first embodiment, the rotation angle interval for detecting the transmission image is made constant, but may be changed as a function of the rotation angle. For example, it is made smaller continuously as it approaches 0 degree (1st rotation position) continuously or in staircase shape.

In addition, when changing the rotation angle interval as a function of the rotation angle, the rotation angle range of the scan need not be limited to 120 degrees or less. That is, as the rotation angle interval, the rotational position may be changed continuously or stepwise so as to be smaller as the rotational position is closer to 0 ° and 180 ° and larger as the rotational position is closer to 90 ° and 270 °.

(Modification 7)

In the first embodiment, the table 4 (battery 90) is rotated with respect to the X-ray beam 2, but the rotation may be relative. For example, the X-ray tube 1 and the X-ray detector 3 may be rotated with respect to the rotation axis RA without rotating the table 4.

In the first embodiment, the table 4 is XY moved relative to the rotation axis RA and the X-ray beam 2, but the XY movement may be relative. For example, the rotation axis RA and the X-ray beam 2 (the X-ray tube 1 and the X-ray detector 3) may be XY moved without moving the table 4 XY.

In addition, although the table 4 is moved z with respect to the X-ray beam 2 in 1st Embodiment, the z movement may be relative. For example, the X-ray beam 2 (the X-ray tube 1 and the X-ray detector 3) may be z-zipped without moving the table 4 z.

(Modification 8)

In the first embodiment, the battery 90 is described as an example, but the subject of the present invention is not limited to the battery, but also has a different layered structure, for example, a capacitor, a coil, a multilayer substrate, and the like. It can be applied effectively.

(Modification 9)

Although X-rays are used as the radiation in the first embodiment, the radiation is not limited to X-rays as long as it is transparent. For example, the radiation may be gamma rays, microwaves, or the like.

1: X-ray tube
2: X-ray beam
3: X-ray detector
4: table
5: subject
6: XY apparatus
7: rotating and lifting mechanism
8: shift mechanism
9: control processing unit
9a: display unit
9b: input
9c: scan control
9d: reconstruction section
10: section view
11: area to be shot
12: layered surface
90: battery
91: case
92: positive electrode plate
93: negative electrode plate
94: electrolyte
101: X-ray tube
102: X-ray beam
103: X-ray detector
104: table
105: subject
105a: interest
106: XY apparatus
107: rotary mechanism
108: control processing unit
109: shift mechanism
110: cross-sectional field of view

Claims (7)

delete A CT device for photographing a cross-sectional image for decomposing the layered structure of a subject having a layered structure composed of a plurality of parallel layers,
Detecting a radiation source that radiates radiation around a radiation optical axis along the tomography surface toward a subject loaded on a table so that the layered surface of the layered structure to be photographed crosses the tomography surface; Radiation detection means for outputting as a transmission image, rotation means for relatively rotating the table and the radiation with respect to a rotation axis orthogonal to the tomography surface,
Priority scan for controlling the rotating means and the radiation detecting means to change the angle on the basis of the rotation angle at which the layer plane becomes parallel to the radiation optical axis while introducing the plurality of transmitted images as scan data and storing the rotation. Scan control means for performing
And reconstructing means for reconstructing at least one cross-sectional image parallel to the tomography surface of the subject from the scan data,
The scan control means is the preferential scan, wherein the layer plane is within ± 60 ° about a first rotational position parallel to the radiation optical axis and the rotation in a first rotational angle range including the first rotational position. And a first scan for introducing and storing the plurality of transmitted images detected as the first scan data while performing the scanning operation. 3. The apparatus according to claim 2, wherein the scan control means includes the second rotational position as the preferential scan and also within ± 60 ° about a second rotational position 180 ° different from the first rotational position. And a second scan for introducing and storing the plurality of transmission images detected while the rotation is in the two rotation angle ranges as second scan data. The said scan control means detects a several transmission image for every 1st rotation angle interval in the said 1st scan,
The scan control means detects every third rotation angle interval greater than the first rotation angle interval while the rotation is in the third rotation angle range as the preferential scan and also includes at least a portion outside the first rotation angle range. And a third scan for introducing and storing the plurality of transmitted images as third scan data. The said scan control means detects the several transmission image for every 1st rotation angle interval in the said 1st scan,
In the second scan, a plurality of transmission images are detected at every second rotation angle interval, and the scan control means detects at least a portion outside the first rotation angle range and the second rotation angle range as the preferential scan. Introducing a plurality of transmitted images detected as the third scan data for every third rotation angle interval greater than either one of the first rotation angle interval and the second rotation angle interval while the rotation in the third rotation angle range including And a third scan for storing. An imaging method of a CT apparatus for photographing a cross-sectional image for decomposing the layered structure of a subject having a layered structure composed of a plurality of parallel layers,
Detecting a radiation source that radiates radiation around a radiation optical axis along the tomography surface toward a subject loaded on a table so that the layered surface of the layered structure to be photographed crosses the tomography surface; Radiation detection means for outputting as a transmission image, rotation means for relatively rotating the table and the radiation with respect to a rotation axis orthogonal to the tomography surface, and controlling the rotation means and the radiation detection means to have a predetermined rotation angle range. In a CT device having scan control means for scanning by introducing and storing a plurality of transmitted images detected while rotating the above as scan data, and reconstructing means for reconstructing a cross-sectional image of the subject from the stored scan data. ,
Specifying a first rotational position at which the layer plane is parallel to the radiation optical axis,
Performing a preferential scan for introducing and storing a plurality of transmission images as scan data by varying an angle with respect to the first rotational position while performing the rotation;
And reconstructing at least one cross-sectional image parallel to the tomography surface of the subject from the scan data. 7. The scan of claim 6, wherein the preferential scan is within a range of ± 60 ° about the first rotational position to include a scan of a first rotational angle range including the first rotational position, or 180 degrees with the first rotational position. A scan of the CT device further comprising a scan of a second rotational angle range including the second rotational position within ± 60 ° about a different second rotational position.

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