JP2003035777A - X-ray detector and x-ray ct equipment using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray detector capable of separating channels and cells in a slice direction due to groove processing with high accuracy even if the taking-out number of signals in the slice direction is increased, and a multi-slice type X-ray CT equipment. SOLUTION: A substrate is loaded with scintillators 2 and an X-ray detection element group 1 including a detection element array 6 having light receiving regions separated in a channel direction and the slice direction and light guides 3 are provided to the boundary parts of the respective cells in the channel direction and the slice direction between the scintillators 2 and the light receiving parts of the detection element array 6. A plurality of the output terminals of the separated light receiving regions and the terminal of the substrate are connected by a wire bonding method. The scintillators 2 and the light guides 3 are matched with the boundary position of the light detection element array 6 to form grooves 9 for isolating the respective cells in the channel direction and the slice direction by trench processing and partition wall materials 10 are inserted in the isolation trenches.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray detector for simultaneously detecting X-ray transmission data of a plurality of slices and an X-ray CT apparatus using the same, and in particular, groove processing even if the number of signals taken out in the slice direction increases. An X-ray detector that can separate cells in the channel and slice directions with high accuracy, and a single scan that can improve the diagnostic ability by reducing the imaging time and motion artifacts using this X-ray detector. The present invention relates to an X-ray CT apparatus that can obtain a multi-slice tomographic image.

[0002]

2. Description of the Related Art In recent years, in an X-ray CT apparatus, a plurality of rows of X-ray detection element arrays are arrayed (that is, two-dimensional array) in the slice direction in order to improve the throughput of the apparatus, and an X-ray CT is operated once.
Collect two-dimensional X-ray data by X-ray exposure and
Attention has been paid to a multi-slice X-ray CT apparatus that can obtain a T image (hereinafter, the X-ray detector used in this multi-slice X-ray CT apparatus will be referred to as a multi-slice X-ray detector). Such a multi-slice X-ray CT
In addition to shortening the inspection time, the apparatus is a conventional detector arranged in a line (hereinafter referred to as a single-slice type X-ray detector, and an X-ray CT apparatus using the detector is a single-slice type X-ray detector).
There is also an advantage that the utilization efficiency of the X-rays emitted from the X-ray tube is higher than that of the X-ray CT apparatus).

The above-mentioned multi-slice type X-ray detector includes
Instead of a conventional ionization chamber type detector using xenon gas, a solid state detector that can obtain high spatial resolution and high S / N (signal / noise) is used. This solid-state detector includes an X-ray detection element group including a scintillator that converts incident X-rays into light and a photodetection element such as a silicon photodiode that detects the light converted by the scintillator and outputs it as an electric signal. , X-ray sources are arranged in the channel direction and in the slice direction orthogonal to the channel direction, and are arranged in a substantially arcuate shape. In this way, in the multi-slice type X-ray detector, since a large number of X-ray detecting elements are arranged in the channel direction and the slice direction, the output signals of these X-ray detecting elements are the conventional single-slice type X-ray detectors.
The number of output signals is much larger than that of line detectors, and how to efficiently extract these output signals in a limited mounting space becomes a major issue.

As described above, since the X-ray CT detector requires a multi-element arrangement, the photo-detecting element for converting the output light of the scintillator into an electric signal does not have a single-channel chip arranged, but a special element. A large number of photo-detecting element arrays each having a plurality of channels formed on one chip, which are disclosed in Japanese Patent Laid-Open No. 2000-316841, are used.

Since the photodetector array must be arranged with high density in a limited mounting space, a semiconductor device such as a silicon photodiode is generally used.

However, the photo-detecting element array of the conventional single-slice type X-ray detector is a one-dimensional array in which the light-receiving portion and the extraction of the output signal are separated only in the direction of a single channel. The photodetector array of the line detector needs to have a two-dimensional array in which the light receiving parts are separated in the channel direction and in the slice direction orthogonal thereto.

Therefore, as a matter of course, the number of element output signals per channel increases corresponding to the number of divisions in the slice direction. Furthermore, in the multi-slice X-ray CT apparatus, it is necessary to change not only the incident X-ray beam width but also the element width in the slice direction of the X-ray detection element in order to change the measurement slice width. That is, when a lesion is examined using an X-ray CT apparatus, the optimum slice thickness at the time of examination differs depending on the examination site, examination range, and target disease. For this reason,
As for the slice thickness of the X-ray CT apparatus, several kinds of thickness dimensions can be selected within the range of about 1 to 10 mm in accordance with the purpose of examination of the subject. Conventional single slice X
In the line detector, the slice thickness at the time of inspection is changed by changing the width of the incident X-ray beam. However, in the multi-slice X-ray detector, unlike the case of the single-slice X-ray detector, only by changing the width of the incident X-ray beam, the slice thickness of the X-ray beam captured by each X-ray detecting element array is changed. It is not possible.

In the case of the multi-slice type X-ray detector, the width of the incident X-ray beam is changed and the state of division of the X-ray element array in the slice direction in the range where X-rays are incident is set to a target slice thickness. Need to be changed accordingly. Therefore, in order to cope with the measurement with several kinds of slice thicknesses, the X-ray detection element is divided into a plurality of photodiode cells in the slice direction as disclosed in Japanese Patent Laid-Open No. 2000-316841. Therefore, it is necessary to change the measurement slice thickness by changing the combination of the outputs of the divided photodiode cells.

As described above, the photo-detecting element array used for the multi-slice X-ray detecting element is multi-divided in the slice direction, and each output thereof can be guided to an external circuit in a desired combination. Must be combined. Usually, this switch array has
As disclosed in the publication 00-316841, it is arranged in the vicinity of the photodetector array and directly connected between them by the wire bonding method, and the output of the switch array is connected to the wiring board by the wire bonding method. The signal is taken out from the connector provided on the external circuit.

The above-mentioned X-ray detecting element array must be arranged in a polygonal shape so as to be substantially in contact with each other in the channel direction so as not to create a gap between adjacent arrays, and therefore the X-ray detecting element array is arranged in a polygonal shape. There is no space for providing a signal extraction portion at the end portion in the channel direction, and it is necessary to perform all signal extraction at the end portion in the slice direction.

[0011]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In order to manufacture a line detection element, a scintillator having a predetermined area and a photodiode array of a plurality of channels must be combined. The scintillator that constitutes this array of X-ray detection elements is manufactured by finishing the individual channel width and slice thickness dimensions in line with the light receiving surface position of the photodiode array and adhering and fixing them. Although it can be manufactured by inserting a partition plate to prevent the X-ray detection, the alignment of the scintillator and the photodiode in the slice and channel directions requires an accuracy of ± 0.05 mm or less. Positioning the element with the accuracy described above is difficult.

As a method of aligning each element with high accuracy, a scintillator plate having a size that covers all channels and all slices of the array is adhered to the light receiving surface of the photodiode array with a transparent adhesive, and then the scintillator end portion is used. There is a method in which a groove is formed in a scintillator on the basis of the exposed photodiode pattern to separate channels and slices. Furthermore, by inserting a partition plate having a light reflection layer on the surface of the groove separated by the groove processing and fixing it, or by filling a resin with a high light reflectance into the groove and curing it. Thus, an X-ray detection element array having excellent positional accuracy can be realized. In this method, since the separation of the channel and the slice is determined by the accuracy of the groove processing machine, it is possible to perform the positioning with high accuracy within the array, but the separation groove between the channels by the groove processing machine is adjacent to each other. In order to eliminate optical crosstalk between channels, it is necessary to completely separate the scintillator and reach the photodiode. If the separation groove does not reach the photodiode, the crosstalk between the channels in the array and the crosstalk between the arrays will be different, and the measurement image at the position corresponding to the end of the channel where these crosstalks occur will appear. Ring-shaped artifacts will occur. Further, since the large optical crosstalk also has the effect of blurring the measurement image, it is necessary to keep the crosstalk amount low in order to obtain an image with high diagnostic ability. Such a ring artifact image is a great obstacle in diagnosing an abnormal part such as a tumor.
The separation groove of the line detection element array has a depth to reach the photodiode, and by inserting a partition plate or a partitioning agent into this groove, optical crosstalk within the array and between arrays is extremely small, and X-ray detection with uniform characteristics is performed. It is necessary to configure the element array.

A multi-slice type X-ray detector having such a configuration is currently put into practical use which is capable of simultaneously obtaining four slice tomographic images in one scan.
The number of slices taken in by the X-ray detector tends to increase in order to perform highly accurate measurement in a short time. For example, if 16-slice measurement can be performed, the data acquired by the scanner in four rotations in the current 4-slice system can be captured in one rotation, and the measurement time can be shortened to 1/4. Thus, shortening the total examination time by speeding up the measurement time has an advantage that the restraint time of the patient to be examined can be shortened. Although increasing the number of captured slices leads to complication of the system, it is possible to shorten the imaging time and improve the diagnostic ability by reducing motion artifacts, so there is a strong demand from the clinical side to have multiple slices.

In order to achieve such desired multi-slices, it is necessary to take out all the outputs of the photodiode array finely separated in the slice direction from the ends in the slice direction, but the area for wire bonding increases accordingly. As a result, it becomes impossible to secure a region for groove processing (a part where wire bonding is not performed and wiring and pads for that purpose are not installed) at the channel boundary part. For this reason, in the above-mentioned conventional technique, when the number of signals taken out in the slice direction increases, there arises a problem that the cells cannot be separated by the groove processing capable of highly accurate alignment. Therefore, an object of the present invention is to provide an X-ray detector capable of highly accurately separating channels and cells in the slice direction by groove processing even if the number of signals taken out in the slice direction increases, and an imaging time using the X-ray detector. It is an object of the present invention to provide a multi-slice X-ray CT apparatus capable of obtaining a multi-slice tomographic image with one scan, which can improve the diagnostic ability by shortening the scan length and reducing motion artifacts.

[0015]

The above object is to provide a scintillator which emits light by detecting incident radiation, and an X-ray detection element group including a photodetection element array having light receiving regions separated in a channel direction and a slice direction. Is mounted on a substrate, and a plurality of X-ray detection element groups mounted on the substrate are arranged in a polygon shape at substantially equal angular pitches on a substantially arc centered on the focal point of the X-ray tube in the channel direction and the slice direction. In the line detector, a light guide is provided at the boundary of each cell in the channel direction and the slice direction between the scintillator and the light receiving portion of the photodetector array, and the plurality of output terminals of the separated light receiving region and the The light guide is connected to the terminals provided on the substrate by a wire bonding method, and the height of the upper surface of the light guide is higher than that of the wire bonding portion. It is achieved by Rukoto. The light guide is formed by stacking glass plates having a light-shielding layer on the surface at a pitch corresponding to the channel width of the photodetector, and the lightguide is aligned with the channel position of the photodetector to detect the photodetector array. Adhere to the light receiving part of the, and then attach the scintillator plate on it, and align the scintillator plate and the light guide with the boundary position of the photodetector to form a groove for separating each cell in the channel direction and the slice direction by groove processing. Then, the partition wall material is inserted into the separation groove, and the separation groove in the channel direction is a depth that completely separates the scintillator plate and slightly enters the light guide layer, and the separation in the slice direction. The groove has a depth that separates most of the light guide layer but does not reach the surface of the photodetection element.

Then, a metal plate having a light reflecting layer or a white resin having a high light reflectance is put on the inner surface of the separation groove of the scintillator plate and the light guide layer to separate the elements between the channels and the slices. In the X-ray detector thus configured, a light guide plate having a structure in which channels are separated is mounted on a light receiving portion of a photodiode, and a channel of a scintillator plate adhered thereon and a groove for slice separation are processed. As a result, the height at which the blade passes can be set higher than that at the wire bonding portion at the end of the photodiode. In this way, by inserting the light guide plate between the photodiode light receiving surface and the scintillator, it is possible to change the passing height of the blade for channel direction separation to any height above the photodiode surface. Therefore, the wire bonding portion for taking out the signal can be provided also in the channel boundary portion of the photodiode array. Therefore, even if the number of extraction signal lines increases due to an increase in the number of divisions in the slice direction, it becomes possible to perform wire bonding for signal extraction by using the entire slice end portion of the photodiode array. Since the groove processing separation can be performed after the plate is adhesively fixed on the photodiode, the alignment accuracy of the scintillator and the photodiode light receiving portion for each element is improved, and an X-ray detection element having a uniform detection characteristic is provided. X-ray detectors are possible. The following light guide plate may be used.

(1) A glass fiber having a diameter of several microns to several tens of microns, which is made of a glass material having a high refractive index for transmitting incident light and a glass material having a low refractive index covering the glass material, has a size not exceeding the outer shape of the scintillator. A light guide plate formed by slicing a bundle of columnar glass fiber bundles with a predetermined thickness.

(2) A light guide plate having a structure in which the low refractive index glass layer of the light guide plate of (1) above contains a light absorber. With the light guide plate having this structure, it is possible to reduce the optical crosstalk to the adjacent fiber and increase the resolution.

(3) A light guide plate having a structure in which the low refractive index glass layer of the light guide plate of the above (1) contains a light reflector. With the light guide plate having this structure, it is possible to reduce the optical crosstalk to the adjacent fiber, improve the resolution and improve the light utilization efficiency.

(4) A light guide plate having a structure for transmitting two-dimensional incident light having a crystal structure for growing a unidirectional crystal in the thickness direction, which is the light guide plate of (1) above.

(5) A light guide plate having a structure in which the glass fiber of the light guide plate of the above (1) is processed into a tapered shape so that the size on the light receiving surface side is smaller than that on the scintillator side. In the light guide plate having this structure, a gap is formed in the channel direction of the light receiving surface, and a bonding wire can be provided there, so that more slices can be made.

In order to achieve the above object, the X-ray CT apparatus of the present invention includes an X-ray tube for irradiating the subject with an X-ray beam, and the subject arranged so as to face the X-ray tube. An X-ray detector that detects the transmitted X-rays and converts them into electric signals,
A preamplifier for amplifying an output signal of the X-ray detector, an AD converter for converting an analog output signal from the preamplifier into a digital signal, at least the X-ray tube and the X-ray detector, and Based on the output signal of the rotating disk that is driven to rotate around
An X-ray CT apparatus including image processing means for reconstructing a line image, wherein the X-ray detector capable of multi-slice is used as the X-ray detector. By using this X-ray detector in an X-ray CT device, multi-slice X-ray CT that can obtain a multi-slice tomographic image in one scan that can improve diagnostic ability by shortening imaging time and reducing motion artifacts The device can be obtained.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The multi-slice X of the present invention will be described below.
An example of a line CT apparatus will be described with reference to the accompanying drawings.

FIG. 8 is a diagram in which the X-ray detector of the embodiment of the present invention is mounted on a scanner rotary plate, and FIG. 9 is a block diagram showing the entire system of the multi-slice X-ray CT apparatus of the present invention.

In FIG. 9, the multi-slice X of the present invention is shown.
The entire system of the line CT apparatus is composed of three units: a scanner 45, a console 46, and an image processing device 47. A scanner rotating plate 35 is rotatably supported at the center of the scanner 45. An X-ray tube 36 and an X-ray detector 38 are mounted on the scanner rotary plate 35 so as to face each other with an opening 41 provided in the center interposed therebetween.

The arrangement of the X-ray detector 38 on the scanner rotary plate 35 will be described with reference to FIG. The X-ray detector 38 is arranged on the rotary scanner plate 35 with the subject 42 inserted into the opening 41 being sandwiched therebetween.
It is arranged so as to face the wire tube 36. X-ray detector 38
Are housed in the detector container 37 together with the collimator plate 39.

The X-ray detector 38 is composed of a plurality of X-ray detecting element arrays 25, and these X-ray detecting element arrays 25 are arranged in a polygonal shape with the focal point of the X-ray tube 36 as the center.
A collimator plate 39 for preventing scattered X-rays incident on the front surface of the X-ray detection element array 25 from the directions other than the focal direction is centered on the focus of the X-ray tube 36. Are arranged in a radial pattern.

An X-ray beam collimator 49 for narrowing the X-ray beam in the slice direction and the channel direction is arranged on the front surface of the X-ray tube 36. For the measurement by the X-ray detector 38, the subject 42 is inserted into the opening 41, and the scanner rotating plate is used.
The object 42 is irradiated with X-rays emitted from the focal point of the X-ray tube 36 while rotating the object 35, and the amount of X-ray transmission from each direction of the object 42 is measured. At this time, X from the focus of the X-ray tube 36
The thickness of the line beam in the slice direction and the width in the channel direction are limited by the X-ray beam collimator 49. The output from the X-ray detector 38 is connected to the amplifier 40. Output signal is amplifier
After being amplified to an appropriate level at 40, it is converted from analog to digital and sent to the subsequent image processing apparatus.

In FIG. 9, the keyboard 5 is attached to the console 46.
4, a scan condition setting circuit 55, an image display device 53 and the like are included to control the scanner 45 and display a slice image of the subject 42.

The scan conditions of the scanner 45 input from the keyboard 54 of the console 46 are input to the scan condition setting circuit 55. In this embodiment, the slice configuration signal (information indicating the slice thickness × the number of slices) 65 is sent to the scanner 45 based on the information about the slice thickness in the scan conditions.
Then, the image addition signal 66 is sent to the image processing device 47, respectively.

The slice configuration signal 65 is received by the scanner control circuit 48 of the scanner 45, where the slice configuration signal 65.
The collimator aperture control signal 67 and the detector switch switching control signal 68 are generated based on the above, and the respective signals 67 and 68 are sent to the X-ray beam collimator 49 and the X-ray detector 38, and the slice of the X-ray beam is sent according to the scanning conditions. Thickness and X-ray detector
The switching condition of the switch circuit of the output signal of the X-ray detection element in the slice direction within 38 is set. The output from the X-ray detector 38 is amplified by the amplifier circuit 40, converted into an analog-digital signal, and sent to the image processing device 47 as measurement data 69 for a plurality of slices.

The image processing device 47 includes an image reconstruction circuit 50,
An image adding circuit 51, a magnetic disk device 52 and the like are included.
In this image processing device 47, the measurement data 69 sent from the scanner 45 is created by the image reconstruction circuit 50 into slice images at a plurality of slice positions corresponding to the array in the slice direction of the X-ray detection elements of the X-ray detector 38. Then, the plurality of slice images are sent to the image adding circuit 51.

The image addition circuit 51 performs addition processing between the reconstructed slice images according to the image addition signal 66 sent from the scan condition setting circuit 55 of the console 46. The final image data 70 obtained in this way is the operation console.
It is sent to the image display device 53 of 46 and stored in a storage device such as the magnetic disk device 52.

Next, the structure of the X-ray detection element array 25 which constitutes the X-ray detector will be described.

FIG. 1 is an external view of an X-ray detection element array according to an embodiment of the present invention. The X-ray detection element array 25 is a photodiode array 6 mounted on the printed circuit board 1.
The scintillator 2 is adhesively fixed to the incident surface (shown in FIG. 2) through the light guide layer 3. The photodiode array 6, the light guide 3 and the scintillator 2 are divided in the channel direction and the slice direction respectively so that the output of each part can be taken out, and the output is wired to the connector 4 so that it can be connected to an external circuit. Has become. The combination of the scintillator 2 and the photodiode 6 constitutes an X-ray detection element. In the case shown, there are 10 X-ray detection elements in the channel direction (depth direction) (10 channels) and the slice direction (horizontal direction). 12) (for 12 slices), a total of 120 are arranged. A desired number of slice thickness data is measured by arranging the required number of X-ray detection element arrays 25 having such a configuration in the channel direction and changing the combination of the outputs of the detection elements with a switch circuit (not shown). Then, the printed board 1 is provided with a mounting hole 5 for arranging and fixing the completed X-ray detecting element array 25 inside the detector container with a screw or the like.
Next, FIG. 2 shows an outline of a method of manufacturing the X-ray detection element array shown in FIG. In the figure, (a) is a scintillator plate 2, (b) is a light guide plate 3 having a structure separated for each channel,
(C) is the substrate 1 on which the photodiode array is mounted. The light guide plate 3 has a size corresponding to the light receiving part of the photodiode array 6 (the channel direction has the same size as the photodiode array light receiving part, and the slice direction has a size slightly larger than the photodiode array light receiving part). A light separation layer is provided with a channel pitch width of 6. This light guide plate 3 is shown in FIG.
As shown in, the light receiving portion of the photodiode array chip 6 is aligned in the channel direction, and is fixed to the light receiving portion of the photodiode array chip 6 with a transparent adhesive. The length of the scintillator plate 2 in the slice direction is substantially the same as that of the light guide plate 3, and the channel direction thereof is slightly larger than the light guide plate 3. This scintillator board 2
As shown in (e) of the figure, the light guide plate 3 adhered to the light receiving portion of the photodiode array is adhered and fixed by a transparent adhesive so that the light guide plate 3 is substantially centered. As a result, the left and right ends of the scintillator plate 2 in the channel direction are fixed so as to slightly protrude from the ends of the light guide plate 3. Next, as shown in FIG.
Based on the position of the channel separation pattern of the photodiode array chip 6 that is slightly exposed near the end of the light receiving portion to which the scintillator plate 2 and the light guide plate 3 are bonded, the scintillator 2 is aligned with the separation position in the slice direction.
And the groove 7 is formed in the light guide plate 3. In this groove 7,
As shown in (g) and (h), a slice direction partition plate 8 that has been subjected to a light reflection treatment is inserted into the surface of a thin metal plate or a resin film, and this partition plate 8 is placed inside the groove with a transparent adhesive. Fix it. Further, separation grooves are also formed by groove processing in the channel direction of the scintillator 2. The depth of the separation groove is set so that the scintillator 2 is completely separated and slightly enters the light guide 3. By inserting and fixing the partition plate 10 in the channel-direction separating groove 9 thus formed, an X-ray detecting element array separated in the slice direction and the channel direction as shown in FIG. To do. Since the scintillator 2 is separated by groove processing based on the pattern of the mounted photodiode array chip 6, the scintillator 2 can be positioned with high precision in the slice direction and the channel direction with respect to the photodiode array chip 6. It will be possible.

Each of the above steps will be described in detail with reference to FIG. Figure 3 shows the X-ray detector array in the slice direction (1
-a to 9-a) and a channel direction (1-b to 9-b).

First, the scintillator plate 3 (1-a, 1-b in FIG. 3)
And a light guide plate 3 (2-a and 2-b in FIG. 3) are prepared, the photodiode array 6 is adhered to the substrate 1, and the output of the photodiode array 6 is taken out to an external circuit. The output terminal of the diode array 6 and the connector 4 of the substrate 1 are connected by wire bonding 11 (see FIG. 3).
3-a, 3-b).

The light guide plate 3 is fixed to the light receiving portion of the photodiode array 6 with a transparent adhesive with the channel direction aligned (4-a and 4-b in FIG. 3). At this time, the thickness of the light guide plate 3 is determined so that the surface of the light guide plate 3 is higher than the wire bonding portion (including protective resin) 11 at the slice end of the photodiode array 6. Since the light guide plate 3 is separated in the slice direction by post-processing, the light guide plate 3 at the time of this bonding
The positioning accuracy in the slice direction is not so required.

Next, the scintillator plate 2 is attached to the light guide plate 3
Then, the photodiode array 6 is bonded and fixed with a transparent adhesive so as to cover the light receiving portion (5-a and 5-b in FIG. 3).
The scintillator plate 2 is wider than the width of the photodiode array 6 in the channel direction (5-b in FIG. 3), and has substantially the same length as the light guide plate 3 in the slice direction (see FIG. 3).
5-a).

The light receiving portion of the photodiode array 6 is covered with the scintillator plate 2 and the light guide plate 3, but is slightly separated from the wire bonding portion 11 connecting the signals from the cells at both ends to the substrate. There is a part where the surface of the photodiode array is exposed. Wiring patterns for guiding signals and pads for wire bonding are formed on the surface of the exposed portion of the photodiode array 6, and the photo that has been covered with the scintillator plate 2 on the basis of these patterns. The light receiving portion position of the diode array 6 can be accurately specified.

Slice direction separation grooves 7 are formed in the scintillator plate 2 and the light guide plate 3 based on the pattern of the photodiode array 6 (6-a in FIG. 3). The separation groove has a depth that leaves the light guide plate 3 at about 20 to 50 μm, and has a depth that does not reach the photodiode array 6 so as not to cut the lead line of the internal slice signal arranged on the photodiode surface. To do. Further, a partition plate 8 is put in the separation groove 7 and fixed in the groove with a transparent adhesive (7-a in FIG. 3). Then, the separation groove 9 is formed in the channel direction (8-b in FIG. 3). Also at this time, the pattern of the exposed portion of the photodiode array 6 is used as a reference for positioning the groove processing.

The depth of the channel direction separation groove 9 reaching the light guide plate 3 is sufficient, and it is not necessary to cut into the vicinity of the surface of the photodiode array 6. This is because the light guide plate 3 has a structure in which it is separated for each channel. With this structure, the grooved blade can be used as a photodiode array.
Since it passes through a position higher than the wire bonding portion 11 of the slice end portion of 6 (near the surface of the light guide plate 3), the wire bonding portion 11 is not damaged by the blade when the channel direction separation groove of the scintillator plate 2 is processed. Absent. Finally, the channel direction separation groove 9
The device block array is completed by inserting the partition plate 10 into the inside and fixing it with an adhesive (9-a, 9- in FIG. 3).
b). Note that, instead of the method of inserting the partition plate into the separation groove as described above, the method of directly inserting the resin or the like having a high surface light reflectance by mixing a white pigment into the separation groove to fix the same is also used. It is possible to perform separation in the slice direction and the channel direction. In this case, as a procedure, the partition plate is formed by forming a separation groove in the slice direction and the channel direction on the scintillator plate 2 adhered to the photodiode array 6 and then filling the grooves in both the slice direction and the channel direction with a resin or the like. It is also possible to simultaneously form the scintillator separation portion instead of the above in the slice direction and the channel direction.

FIG. 4 shows a state of signal wiring of the photodiode array 6. The output of the light receiving portion 12 inside the photodiode array 6 is guided to the end portion in the slice direction by the wiring line 13 laid on the surface.

A wire bonding pad 14 is provided at this end.
Is provided. Bonding pads 15 are also provided at corresponding positions on the printed circuit board 1 to provide a photodiode array.
6 and the respective bonding pads 14 of the printed circuit board 1
By connecting the wires 16 and 15 with a wire 16 (wire bonding method), the output electric signal of the photodiode array 6 is taken out to the wiring line 17 of the printed board 1. Since the wire 16 is extremely thin, it is easily cut off when an external force is applied or peeled off from the pad, so the wire 16 is covered and fixed after the bonding work, and the external force is not applied directly to each wire. To protect.

When the number of divided light-receiving portions of the photodiode array 6 in the slice direction is small and the number of signal lines for wire bonding connection at the end is small, the wire bonding pads 14 and
I can afford to place 15. When the number of divisions in the slice direction as in the above-mentioned conventional is small, as shown in FIG. 11, the boundary portion where the wire bonding pad is not arranged is a grooved portion to separate the scintillator plate after adhering the scintillator plate to the photodiode array light receiving portion. Processing can be performed. However, if the number of divisions in the slice direction is increased, in order to arrange many wire bonding pads as shown in FIG. 4,
It is unavoidable to arrange the wire bonding pad by utilizing the vicinity of the channel boundary. Therefore, in the case of more slices than the conventional one, the conventional method of separating with a groove machine after the scintillator plate is bonded cannot be applied as it is. In order to solve this problem, in the embodiment according to the present invention, a light guide plate provided with a light separation layer for each channel is adhered to the light receiving portion of the photodiode array, and when the scintillator plate is separated as shown in FIGS. 5 and 6. The position where the groove cutting cutter passes is set higher than the wire bonding portion. As described above, although the step of adhering the light guide plate is increased by one, accurate alignment can be performed based on the pattern of the photodiode array as in the conventional case, and the scintillator can be divided.

Next, a method of manufacturing the light guide plate 3 will be described. Fig. 7 shows the appearance of the light guide plate in the process (1-a to 6 to explain the manufacturing process of the light guide plate.
-A) and an enlarged view of a cross section (1-b to 6-b). First, a glass plate 19 having a thickness corresponding to the channel pitch of the photodiode array is prepared (1-a, 1- in FIG. 7).
b). Aluminum light reflection layers 20 are formed on both surfaces of the glass plate 19 by a vapor deposition method or the like (2-a and 2-b in FIG. 7).
The glass plates 19 having the light reflection layers 20 formed on both surfaces are laminated by the number of channels of the photodiode array ((3− in FIG. 7-
a, 3-b), and the space between them is adhered and fixed by an adhesive to form the glass laminate 21 (4-a, 4-b in FIG. 7).

At this time, the portion where the adjacent light reflection layers 20 are bonded together becomes the light separation layer 22 between the channels when the light guide is completed (4-b in FIG. 7). By slicing the glass laminated body 21 integrated in this manner with an inner peripheral slicer or a wire saw so as to have a predetermined thickness (5-
a, 5-b), and the light guide plate 3 provided with the light separation layer between the channels is completed (6-a, 6-b in FIG. 7).

Here, the light guide plate 3 has been described as having the light separation layer provided only between the channels, but it is also possible to use the light guide plate 3 provided with the light separation layer in a matrix form between the channels and between the slices. Is. When using the light guide plate provided with a separation layer in each of the slice direction and the channel direction, the depth of the inter-slice separation groove for separating the scintillator plate is sufficient to reach the light guide plate 3, Diode array
It is not necessary to cut near the surface of 6. The light guide plate provided with the light separating layers in a matrix form the light reflecting layers on both sides, and then stacking and integrating the light guiding plates so that the thickness is in the direction orthogonal to the light reflecting layer and corresponding to the slice direction pitch. It can be manufactured by slicing into slices, providing a light-reflecting layer on the slice surface, then re-adhering, and slicing in a direction orthogonal to the light-reflecting layer in the channel direction and the slice direction. Incidentally, the light guide plate of the above-mentioned embodiment is described using only a glass plate,
The following may also be used.

(1) A glass fiber having a diameter of several microns to several tens of microns made up of a glass material having a high refractive index for transmitting incident light and a glass material having a low refractive index for covering the glass material is set to a size not exceeding the outer shape of the scintillator. A light guide plate formed by slicing a bundle of columnar glass fiber bundles with a predetermined thickness.

(2) A light guide plate having a structure in which the low refractive index glass layer of the light guide plate of (1) above contains a light absorber. With the light guide plate having this structure, it is possible to reduce the optical crosstalk to the adjacent fiber and increase the resolution.

(3) A light guide plate having a structure in which the low refractive index glass layer of the light guide plate of (1) above contains a light reflector. With the light guide plate having this structure, it is possible to reduce the optical crosstalk to the adjacent fiber, improve the resolution and improve the light utilization efficiency.

(4) A light guide plate having a structure for transmitting two-dimensional incident light having a crystal structure for growing a unidirectional crystal in the thickness direction, which is the light guide plate of (1) above.

(5) A light guide plate having a structure in which the glass fiber of the light guide plate of the above (1) is processed into a tapered shape so that the size on the light receiving surface side is smaller than that on the scintillator side. In the light guide plate having this structure, a gap is formed in the channel direction of the light receiving surface, and a bonding wire can be provided there, so that more slices can be made.

As described above, the present invention is not limited to the above-mentioned embodiment, and the structure of the X-ray detection element array can be changed without departing from the gist of the present invention.

[0055]

EFFECT OF THE INVENTION A light guide having a structure separated at a boundary between a channel and a slice of a photodetector is provided between a scintillator and a light receiving portion of the photodetector, and the height of the upper surface of the light guide is set at a wire bonding portion. Even if the number of extraction signal lines increases due to an increase in the number of divisions in the slice direction, wire bonding for signal extraction can be performed using the entire slice edge portion of the photodiode array. As a result, it is possible to perform groove processing separation after the scintillator plate is adhesively fixed on the photodiode, so that the alignment accuracy of the scintillator and the photodiode light receiving part for each element is improved, and X-rays with uniform detection characteristics are obtained. An X-ray detector having a detection element becomes possible, and a multi-slice tomographic image can be obtained by one scan capable of improving diagnostic ability by shortening imaging time and reducing motion artifacts by using this X-ray detector. A multi-slice X-ray CT apparatus can be provided.

[Brief description of drawings]

FIG. 1 is an external view of an X-ray detection element array according to the present invention.

FIG. 2 is a diagram schematically showing a manufacturing process of an X-ray detection element array according to the present invention.

FIG. 3 is a diagram showing details of the manufacturing process of the X-ray detection element array according to the present invention.

FIG. 4 is a diagram showing a signal connection state of a photodiode array forming an X-ray detection element array according to the present invention.

FIG. 5 is a diagram showing a relationship between a blade passing height and a wire bonding portion and a light guide plate surface height at an end portion of the photodiode array when a channel separation groove is formed in the X-ray detecting element array according to the present invention.

FIG. 6 is a view showing a state of forming a channel separation groove at an end portion in the slice direction of a photodiode array forming an X-ray detection element array according to the present invention and inserting a partition wall material into the groove.

FIG. 7 is a view showing a manufacturing process of a light guide plate of an X-ray detection element array according to the present invention.

FIG. 8 is a diagram in which an X-ray detector according to the present invention is mounted on a scanner rotating plate.

FIG. 9 is a block diagram showing the entire system of a multi-slice X-ray CT apparatus of the present invention.

FIG. 10 is a diagram showing a state of mounting a photodiode array on a conventional printed circuit board and signal connection.

FIG. 11 is a view showing a state of forming a channel separation groove at a slice direction end of a conventional photodiode array and inserting a partition wall material into the groove.

[Explanation of symbols]

1 ... Printed circuit board, 2 ... Scintillator, 3 ... Light guide, 4 ... Connector, 5 ... Mounting hole, 6 ... Photodiode array, 7 ... Slice separation groove, 8 ... Slice direction partition material, 9 ... Channel separation groove, 10 ... Channel direction partition material, 11 ... Wire bonding part, 12 ...
..Light receiving element (on photodiode array), 13 ... Surface wiring line (on photodiode array), 14 ...
Bonding pad (on photodiode array), 1
5 ... Bonding pad (on printed circuit board), 16 ...
Bonding wire, 17 ... Wiring line (on printed circuit board), 18 ... Protective resin (wire bonding part),
19 ... Glass plate, 20 ... Light reflection layer, 21 ... Glass laminated body, 22 ... Light separation layer, 25 ... X-ray detection element array,
35 ... Rotating plate, 36 ... X-ray tube, 37 ... Detector container,
38 ... X-ray detector, 39 ... Scattered X-ray removal collimator plate group, 40 ... Amplification circuit, 41 ... Central opening, 42 ...
Object, 45 ... Scanner, 46 ... Operation console, 47 ... Image processing device, 48 ... Scanner control circuit, 49 ... X-ray beam collimator, 50 ... Image reconstruction circuit, 51 ... Image addition circuit, 52 ... Magnetic disk device, 53 ... Image display device 54 ... Keyboard, 65 ... Slice configuration signal, 6
6 ... image addition signal, 67 ... collimator aperture control signal,
68 ... Detector switch switching control signal, 69 ... Measurement data, 70 ... Image data

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 31/0232 H01L 31/00 A 31/09 31/02 C F term (reference) 2G088 EE02 FF02 GG14 GG19 JJ05 JJ09 JJ37 4C093 AA22 BA03 CA06 CA13 CA27 EB12 EB18 EB20 5F088 BA20 BB07 EA04 JA10 JA14 JA17 LA08

Claims (5)

[Claims] 1. A scintillator that emits light by detecting incident radiation and an X-ray detection element group including a photodetection element array having a light receiving region separated in a channel direction and a slice direction are mounted on a substrate. An X-ray detector having a plurality of X-ray detection element groups mounted on a polygonal shape arranged in a polygonal shape at substantially equal angular pitches on a substantially circular arc centered on the X-ray tube focus in the channel direction and the slice direction. A light guide is provided at the boundary of each cell in the channel direction and the slice direction between the light receiving portion of the photodetector array and between the plurality of output terminals of the separated light receiving area and the terminal provided on the substrate. X-ray detection, characterized in that the height of the upper surface of the light guide is higher than that of the wire bonding portion. vessel. 2. The light guide is formed by laminating glass plates having a light-shielding layer on the surface at a pitch corresponding to the channel width of the photodetector, and aligning the lightguide with the channel position of the photodetector. Adhesive to the light receiving part of the photodetector array, and a scintillator plate on it to align the scintillator plate and the light guide to the boundary position of the photodetector, and groove between the cells in the channel and slice directions. The X-ray detector according to claim 1, wherein a groove for separation is formed and a partition material is inserted into the separation groove. 3. The separation groove in the channel direction is a depth that completely separates the scintillator plate and slightly penetrates into the light guide layer, and the separation groove in the slice direction is larger than the light guide layer. The X-ray detector according to claim 2, wherein the depth is such that the portion is separated but does not reach the surface of the photodetection element. 4. The element between channels and slices is separated by inserting a metal plate having a light reflecting layer or a white resin having a high light reflectance on the inner surface of the separation groove of the scintillator plate and the light guide layer. The X-ray detector according to claim 3. 5. An X-ray tube for irradiating a subject with an X-ray beam, and an X-ray detector that is arranged so as to face the X-ray tube and detects the X-rays that have passed through the subject and converts it into an electrical signal. A preamplifier for amplifying the output signal of the X-ray detector, an AD converter for converting an analog output signal from the preamplifier into a digital signal, and at least the X-ray tube and the X-ray tube.
An X-ray CT apparatus that includes a rotating disk that holds a line detector and is driven to rotate around the subject, and an image processing unit that reconstructs an X-ray image based on an output signal of the AD converter. An X-ray CT apparatus using the X-ray detector according to claim 1 as the X-ray detector.