JP2000346948A - X-ray detector for x-ray ct apparatus and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an X-ray detector for X-ray CT apparatus without any dispersion in characteristic between X-ray detection elements arranged in a channel direction and a slice direction. SOLUTION: An X-ray detection element array 8 composing the X-ray detector consists of an X-ray detection element 7 that is arranged in a channel direction and a slice direction on a printed-circuit board 1. Each X-ray detection element 7 is composed of a scintillator 5 and a photo detector 2. The photo detector 2 is formed as a photo detector array 3 on the printed-circuit board 1, and the scintillator 5 adheres onto it. The area between the scintillators 5 is separated by a channel direction separation groove 11 and a slice direction separation groove 12. Light reflection layers 10, 13, and 14 formed of a light reflection material are formed in the channel direction separation groove 11 and the slice direction separation groove 12 on the upper surface of the scintillator 5. A guide member 9 with a reference surface in that a light reflection layer is formed is studs to an end part in the slice direction. The depth of the separation grooves 11 and 12 nearly reaches the photo detector 2.

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 used in an X-ray CT apparatus, and more particularly to an X-ray detector for an X-ray CT apparatus capable of simultaneously measuring a plurality of slices of image data.

[0002]

2. Description of the Related Art In recent years, as an X-ray detector used in an X-ray CT apparatus, in order to improve X-ray detection accuracy, a solid-state detector using a scintillator has been used instead of a conventional ionization chamber system using xenon gas. Vessels have become widely used.
The solid state detector includes an X-ray detection element including a scintillator that converts incident X-rays into light, and a light detection element such as a silicon photodiode that detects light converted by the scintillator and outputs the light as an electric signal. A large number of channels are arranged in an arc shape around the X-ray source.

In the X-ray CT apparatus, it is desired to reduce the time required to obtain one CT image in order to improve the throughput of the apparatus. To reduce this time,
There are two. (1) Reduction of the time required for one rotation of the scanner (2) Increase in tomographic images that can be captured per rotation of the scanner

[0004] Regarding (1), X-ray generator X
The rotation speed of the scanner has been improved by reducing the weight of the wire tube. On the other hand, regarding (2), in the X-ray detector, the rows of the X-ray detection elements which have been arranged one-dimensionally in the channel direction until now are changed to two rows or two rows in the slice direction (the direction orthogonal to the channel direction). This is achieved by arranging a plurality of rows as described above. Such an X-ray detector is called a multi-slice X-ray detector (in contrast, a conventional one-dimensional array X-ray detector is called a single-slice X-ray detector).

FIG. 1 is a schematic view of a multi-slice type X-ray detector.
See Figure 12. FIG. 12 shows the relationship between the multi-slice X-ray detector 103, the subject 102, and the X-ray tube 101. In FIG. 12, the multi-slice type X-ray detector 103 includes four X-ray detection element rows 105 arranged in the slice direction, and thus receives the X-ray beam 104 emitted from the X-ray tube 101. This makes it possible to measure image data of an area corresponding to four slices from the slice 1 to the slice 4 of the subject 102. As a result, there is an advantage that the use efficiency of the X-ray beam 104 from the X-ray tube 101 is quadrupled as compared with the conventional single slice type X-ray detector. The advantage is X
The number of the line detection element rows 105 is increased and the number is improved.

[0006] Multi-slice X-ray detectors have been developed based on conventional single-slice X-ray detector technology, and many methods of arranging single-slice X-ray detectors in the slice direction have been advanced. . However, in the multi-slice X-ray detector, when the X-ray detection elements are arranged in a plurality of rows in the channel direction and the slice direction, respectively,
It is necessary that the performances of the individual X-ray detection elements are sufficiently uniform as a whole. If there is a variation in performance between the X-ray detection elements, ring artifacts or the like will occur in the reconstructed CT image, and the image quality will be degraded.

[0007] Further, if there is a variation in the performance of the X-ray detecting element in the slice direction, even if the image data of the same slice plane of the subject 102 is measured, the image data is measured by the X-ray detecting element at any position in the slice direction. Differences may occur in the measurement data depending on the situation, and the image quality of the CT image and the medical information obtained from the CT image may be different.
Despite measuring image data of the same slice plane of the same subject 102, CT images should never be different due to different X-ray detection elements used for measurement. . For this reason, it is necessary that the characteristics of the X-ray detection element are sufficiently uniform not only in the channel direction but also in the slice direction.

From the above, in order to arrange the X-ray detecting elements two-dimensionally in the multi-slice type X-ray detector, the
The manufacturing method, including the structure of the entire X-ray detector and the structure of each X-ray detection element, is more complicated than the conventional one-dimensional array single-slice X-ray detector. Sufficient accuracy is also required in the assembly process. In addition, in order to make the characteristic values of the X-ray detection elements uniform, it is important to provide uniformity of the characteristics of the scintillator and to provide appropriate light reflecting means on the top and side surfaces of the scintillator. In addition to the light reflection, it is also important to prevent crosstalk on the side surface of the scintillator by X-ray shielding.

An example of a conventional single slice type X-ray detector is shown in FIGS. FIG. 13 is a schematic diagram showing the entire structure of a single-slice X-ray detector, and FIG. 14 is an external view and a sectional view of an X-ray detection element array constituting the single-slice X-ray detector. In FIG. 13, a single-slice X-ray detector 110 is composed of a plurality (11 in the figure) of X-ray detection element arrays 112, and the whole is accommodated in an X-ray detector container 113. X-ray detection element array 112 is X
The X-ray receiving surface of the scintillator is arranged in a polygonal shape (hereinafter, referred to as a polygon) on an arc centered on the focal point of the X-ray tube so as to face the focal point of the X-ray tube. A light reflection film 111 having a high light reflectance is provided on the X-ray tube focal point facing surface side of the X-ray detection element array 112. The light reflecting film 111 is provided to prevent light emitted in the scintillator of the X-ray detecting element array 112 from leaking outside. The configuration shown in FIG. 13 is also employed in a multi-slice X-ray detector.

FIG. 14B is a cross-sectional view taken along the line AA of FIG. 14A, and shows a main part of the X-ray detecting element array 112.
In FIG. 14B, the X-ray detecting element array 112 includes a plurality of X-ray detecting elements 115, and each X-ray detecting element 115 includes a scintillator 116 and a light detecting element (eg, a silicon photodiode) 117. . X-ray detection element array 112
Are formed on a printed circuit board 120, and a channel direction separating groove is provided between the scintillators 116 of each X-ray detecting element 115.
A metal plate 119 having a high light reflectance is inserted into the channel direction separation groove 118. This metal plate 119
Is to prevent light emitted from the scintillator 116 of each X-ray detecting element 115 from leaking to the scintillator 116 of an adjacent element. Similarly, the light reflecting film 111 shown in FIG. 13 prevents light emitted from the scintillator 116 from leaking to the upper surface.

Next, an example of a method of manufacturing the X-ray detecting element array 112 will be briefly described. In FIG. 14B, first, a photodetector array (122) in which photodetectors 117 such as silicon photodiodes are arranged in a plurality of channels is formed on the upper surface of the printed circuit board 120. A scintillator plate (123) covering the entire photodetector array (122) is adhered to the upper surface of the photodetector array (122) with a transparent adhesive 121. The scintillator plate (123) is one in which light emission characteristics by X-ray irradiation are made uniform over the entire surface of the plate. Next, each scintillator plate (123) includes
Corresponding to 17, a channel direction separation groove 118 for separating individual channels is formed. The depth of the channel direction separation groove 118 is almost such that it reaches the photodetector array (122). Furthermore, each channel direction separation groove 118
The metal plate 119 is inserted into. This metal plate 119 is also attached to the outer surface of the scintillator 116 of the X-ray detection elements 115 at both ends.

The above single slice type X-ray detector is
2D radiation solid state detector arranged in two dimensions
No. 44 (hereinafter, referred to as a first known example). In this X-ray detector, after a scintillator plate and a photodiode substrate are bonded, a channel direction separation groove and a slice direction separation groove are cut into the scintillator plate, and a metal plate having a high light reflectance is inserted into the groove. . Since this metal plate crosses vertically and horizontally, a groove with a depth of approximately half the height of the plate is machined at the crossing position, for example, a groove in the upper half in the channel direction and a groove in the lower half in the slice direction. The grooves of the metal plate in both directions are fitted, assembled into a lattice, and inserted into each separation groove.

As the light reflecting means of the scintillator of the X-ray detecting element, other than the above, there are a method of depositing aluminum on the upper surface of the scintillator (conventional example 1) and a method of attaching a light reflecting film (conventional example 2). .

Japanese Patent Application Laid-Open No. Hei 7-48615 (hereinafter referred to as a second known example) discloses a scintillator in which a scintillator plate and a light reflecting plate are alternately stacked in a sandwich shape by the number of channels and cut. A method for manufacturing a single-slice X-ray detector is disclosed in which an array is formed, this is attached to a photodiode array formed on a printed circuit board, and a light reflection layer is further provided on the upper surface of the scintillator array. .

Japanese Patent Application Laid-Open No. 9-54161 (hereinafter referred to as a third known example) discloses that after forming a light reflecting film on a single scintillator plate, the scintillator plate is cut into an elongated rectangular shape, and each cut piece is cut. Single-slice type X-ray detection, in which the light reflecting film surface is sandwiched by a scintillator in a sandwich shape and bonded by the number of channels (that is, rearranged) and then bonded to the photodiode array surface on a printed circuit board A method of making a vessel is disclosed.

Japanese Patent Laid-Open Publication No. Hei 5-16060 (hereinafter referred to as a fourth known example) discloses a method for manufacturing a scintillator.
After forming lattice-shaped cut grooves orthogonal to each other from the light emitting surface of the BGO scintillator crystal, the grooves are filled with a resin solution containing a light reflecting material powder under reduced pressure, and the solvent is removed under reduced pressure to remove light reflection. Techniques for forming layers are disclosed.

[0017]

After tens of X-ray detecting element arrays 112 are arranged in a polygonal shape as shown in FIG. 13, a light reflecting film 111 (or a light reflecting plate) is tightly fixed from the upper surface of the array group. In the structure, the light reflection film 111 and the like are fixed in an arc shape with respect to the X-ray detection element array 112 arranged in a polygon, and the upper surface of the X-ray detection element array 112 and the light reflection film 111 and the like are fixed. Different gaps are generated between the channels between the channels, and variations in the light reflectance due to the gaps, that is, variations in the output, occur between the channels, causing a problem of deteriorating the output characteristics of the X-ray detector. Since the configuration shown in FIG. 13 is also employed in the multi-slice X-ray detector, the characteristics of the multi-slice X-ray detector in the channel direction pose a similar problem.

Further, in the first known example, when a metal plate as a light shielding means inserted for separation in the channel direction and the slice direction is inserted into the channel and the slice direction separation groove, the metal plate is placed on the upper surface of the scintillator. Since the projections protrude and the variation in the amount of protrusion occurs due to the processing accuracy of the metal plate, when pressing the light reflection film 111 or the like from the upper surface as shown in FIG. 13, the distance between the upper surface of the X-ray detection element array and the light reflection film 111 or the like is reduced. , Different gaps are generated for each X-ray detection element, which causes variations in output,
Similarly, the output characteristic of the X-ray detector deteriorates.

In the first known example, the metal plate inserted into the channel direction separation groove and the metal plate inserted into the slice direction separation groove are fitted in the grooves provided in each metal plate to form a lattice-like shape. Since the metal plates are formed, the groove spacing and the groove width of each metal plate are processed with high precision, and precision is required for the combination and fitting of the metal plates, so that there is a problem that the operation cost increases.

Further, in the method of performing aluminum vapor deposition on the upper surface of the scintillator of the conventional example 1, a step of polishing the vapor deposition surface before vapor deposition is required to perform strong vapor deposition, which increases the operation cost. Problem arises.

Also, in the method of pasting the light reflecting film of Conventional Example 2 on the upper surface of the scintillator, burrs appear on the cut surface of the light reflecting film when the groove processing for separating the channel direction and the slice direction is performed. There are also problems such as the incorporation of bubbles when the film is bonded.

The second and third known examples are effective methods for manufacturing a single-slice X-ray detector, but are not directly applied to a multi-slice X-ray detector. Have difficulty. In addition, since the scintillator of each X-ray detection element is cut out from a different scintillator plate, there is also a problem that characteristics are varied between channels.

Further, in the fourth known example, the separation groove is formed in the channel direction and the slice direction with the scintillator alone, the light reflecting material is filled, and then the bonding to the light detecting element is performed. The depth of the groove cannot be sufficiently taken, and the prevention of light leakage to an adjacent element is insufficient;
Since the work of filling the light reflecting material is performed under reduced pressure, problems such as an increase in operation cost occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an X-ray CT apparatus having no characteristic variation between X-ray detecting elements arranged in the channel direction and slice direction. X-ray detector for use, a method for manufacturing the same, and an X-ray CT apparatus.

[0025]

In order to achieve the above object, an X-ray detector for an X-ray CT apparatus according to the present invention comprises a scintillator for detecting and emitting incident radiation and receiving light emitted from the scintillator. An X-ray detection element array in which a plurality of X-ray detection elements in combination with a light detection element that generates an output signal corresponding to the dose of radiation detected by the scintillator are arranged in a substantially arc shape in the channel direction is orthogonal to the channel direction. -Ray CT arranged in multiple rows in the slice direction
In an X-ray detector for an apparatus, a channel direction separation groove and a slice direction separation groove for separating each X-ray detection element in a channel direction and a slice direction are provided in a scintillator portion, and the depth of the separation groove is determined by a photodetection element. The light reflecting material is coated or filled on the upper surface of the scintillator, the channel direction separating groove and the slice direction separating groove of each X-ray detecting element to form a light reflecting layer (claim 1).

In this configuration, the scintillators of all the X-ray detecting elements constituting the X-ray detector are separated by the channel direction separating groove and the slice direction separating groove, and the upper and side surfaces thereof have a high light reflectance. Each X-ray detecting element is efficiently separated from each other in the channel direction and the slice direction because it is surrounded by the layers, and light emitted in the scintillator of each X-ray detecting element does not leak to the outside. The light is transmitted to the light detecting elements, and the uniformity of the X-ray detecting performance of each X-ray detecting element is ensured. As a result, a high-precision X-ray detector for an X-ray CT apparatus having no performance variation as the whole X-ray detector can be obtained.

The X-ray detector for an X-ray CT apparatus according to the present invention further comprises a plurality of X-ray detection element arrays divided into a plurality of blocks in the channel direction.
Line detection element arrays are arranged in a substantially arc shape (polygon shape). The X-ray detection element array is arranged on a printed circuit board. In this configuration, since the X-ray detector is subdivided into a plurality of X-ray detection element arrays, the production becomes easy, and the characteristics of the X-ray detection elements can be made uniform.

The X-ray detector for X-ray CT according to the present invention further comprises:
A guide member having a reference surface for coating or filling a light reflecting material is attached to both ends in the slice direction of the line detection element array. In this configuration, a guide member having a reference surface is attached to both ends in the slice direction of the X-ray detection element array, and the top and side surfaces of the scintillator are coated with the light reflecting material using the reference surface of the guide member. Can be filled, the thickness of the light reflection layer,
In particular, the thickness of the light reflection layer on the upper surface of the scintillator can be made uniform and uniform. As a result, it is possible to ensure uniformity of the X-ray detection characteristics of each X-ray detection element. Also,
Since both ends of the X-ray detecting element array in the slice direction have a space, there is no hindrance in the arrangement of the X-ray detectors.

According to the method of manufacturing an X-ray detector for an X-ray CT apparatus of the present invention, a scintillator plate is provided on an upper surface of a photodetector array formed by arranging a plurality of photodetectors on a printed circuit board in a channel direction and a slice direction. A second step of forming a slice-direction separation groove having a depth until reaching the photodetector array in the scintillator plate corresponding to each slice boundary position of the photodetector in the slice direction. Step, a third step of adhering a guide member for securing a height reference surface at both ends in the slice direction of the scintillator plate, and light on the upper surface of the scintillator plate and the slice direction separation groove with reference to the guide member. A fourth step of filling a reflective material to form a light reflection layer and a slice direction separation layer on the upper surface of the scintillator plate; A fifth step of forming a channel direction separation groove in the scintillator plate corresponding to the channel boundary position until the light detection element array is almost reached, and filling the channel direction separation groove with a light reflecting material based on the guide member. Forming a channel direction separation layer (claim 2).

In this configuration, first, since one scintillator plate is used, uniform X-ray detection characteristics are secured for the entire X-ray detection element array. Further, since the slice direction separation groove and the channel direction separation groove are processed to a depth almost reaching the photodetector and filled with the light reflecting material, light emitted from the scintillator is less likely to leak to the adjacent scintillator. In addition, since the light reflecting material is filled using the depth reference surface of the guide member, the light reflecting layer on the upper surface of the scintillator is formed uniformly and uniformly, light leakage from the upper surface of the scintillator is eliminated, and light Even if there is a leak, uniformity is ensured. Therefore, in the X-ray detector manufactured by this manufacturing method, the uniformity of the X-ray detection performance is ensured, the manufacturing yield is improved, and the manufacturing cost is reduced.

In the method of manufacturing an X-ray detector for an X-ray CT apparatus according to the present invention, in the fourth step and the sixth step, the light reflecting material is pressurized by a pressing plate, and the upper surface of the scintillator plate, the slice direction The separation groove and the channel direction separation groove are filled. In this configuration, by pressing the light reflecting material, the work can be performed at room temperature in the atmosphere, and the light reflecting material can be pushed in along each separation groove. No air bubbles or foreign substances are mixed into the layer, and a uniform light reflecting layer can be obtained.
Further, since the operation can be performed in the atmosphere, the operation cost can be reduced.

The X-ray CT apparatus of the present invention uses an X-ray detector to detect X-rays transmitted through a subject to obtain a CT image.
In the X-ray CT apparatus, the X-ray detector is the X-ray C of the present invention.
It is an X-ray detector for a T device (Claim 3). With this configuration, by applying the X-ray detector for an X-ray CT apparatus of the present invention, a plurality of CT images can be acquired with good image quality in one scan.

[0033]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a first embodiment of an X-ray detector for an X-ray CT apparatus according to the present invention. FIG. 1A is an external view of an X-ray detection element array constituting an X-ray detector, FIG. 1B is a cross-sectional view of the X-ray detection element array of FIG.
FIG. 2C is a cross-sectional view of the X-ray detection element array of FIG. The X-ray detector for an X-ray CT apparatus of the present invention is shown in FIG.
As shown in FIG. 13, a plurality of X-ray detecting element arrays 8 shown in FIG. 13A are arranged in a polygonal shape on an arc centered on the focal point of an X-ray tube.

In FIG. 1A, an X-ray detecting element array 8 is arranged on a printed circuit board 1. X-ray detection element array 8
Is composed of a plurality of X-ray detecting elements arranged in the channel direction and the slice direction. The channel direction is the width direction of the printed circuit board 1 and is the same as the channel direction of the conventional single slice type X-ray detector. The slice direction is a longitudinal direction of the printed circuit board 1 and is a direction orthogonal to the channel direction. Therefore, FIG. 1B is a cross-sectional view of the X-ray detection element array 8 in the channel direction, and FIG. 1C is a cross-sectional view of the X-ray detection element array 8 in the slice direction.

In FIG. 1B and FIG. 1C, a silicon photodiode array 3 is formed on a printed board 1 and the silicon photodiode array 3 is formed.
A scintillator 5 is adhered to the upper part of 3 with a transparent adhesive 4. The silicon photodiode array 3 includes the silicon photodiodes 2 arranged in the channel direction and the slice direction, and the number of the silicon photodiodes 2 corresponds to the required number of the X-ray detection elements 7.

The X-ray detecting element 7 comprises the scintillator 5 and the silicon photodiode 2. Between the X-ray detection elements 7, a channel direction separation layer 13 in the channel direction and a slice direction separation layer 14 in the slice direction.
Are separated by Further, an upper surface light reflecting layer 10 is formed on the upper surface of the scintillator 5. Channel direction separation layer 13, slice direction separation layer 14, and top light reflection layer 10
Is made of a light reflecting material. Here, the material of the scintillator 5 is the same as that of the conventional single slice type X-ray detector.
A solid material that emits light by detecting radiation such as X-rays, for example,
BGO or GdWO4 is used. The silicon photodiode 2 is not limited to this, and another photodetector may be used. The transparent adhesive 4 interposed between the scintillator 5 and the silicon photodiode 2 has a good light transmittance,
An adhesive that does not undergo discoloration by X-ray irradiation, decrease in adhesive strength, or damage such as cracks is suitable.

The bonding between the scintillator 5 and the silicon photodiode 2 is performed when the scintillator 5 is a material scintillator plate, and the bonding is performed between the scintillator plate and the silicon photodiode array 3. After the bonding, a channel direction separation groove 11 and a slice direction separation groove 12 are formed in a portion of the scintillator plate in correspondence with a boundary position of each silicon photodiode 2 with reference to the silicon photodiode array 3. The depth of the two separation grooves 11 and 12 is generally such that it reaches almost the silicon photodiode array 3 through the thickness of the scintillator plate. However, it may be slightly shallower in relation to wiring and the like.

On the upper surface of the scintillator 5, the channel direction separation groove 11 and the slice direction separation groove 12, light reflecting layers 10, 1 are provided.
3 and 14 are formed. When the scintillator 5 emits light by X-rays, the light reflecting layers 10, 13, and 14 are disposed above the scintillator 5 in order to efficiently transmit the light emission to a photodetector such as the silicon photodiode 2 and convert the light emission into an electric signal. Alternatively, a material which is provided for the purpose of shielding light from leaking to the side and has a high light reflectance is selected.

The light reflecting material of the upper light reflecting layer 10 formed on the upper surface of the scintillator 5 is, for example, a white adhesive obtained by adding a white material such as titanium dioxide (TiO2) or barium oxide to an epoxy resin or the like. . For selection of a resin or a white material, a material having a small X-ray attenuation or a material having a small performance deterioration due to X-ray irradiation is suitable. This is because, in the case of a material having a large X-ray attenuation, the X-ray incident on the scintillator 5 is attenuated by the upper light reflection layer 10, so that the incident X-ray cannot be efficiently captured.

The channel direction separation groove 11 and the slice direction separation groove 12 are also filled with a light reflecting material in order to form a light reflecting layer similar to the upper surface light reflecting layer 10 formed on the upper surface of the scintillator 5. A channel direction separation layer 13 between channels and a slice direction separation layer 14 between slices are formed. The light reflecting material used for the channel direction separation layer 13 and the slice direction separation layer 14 is the adjacent scintillator 5
It is preferable to use a material that has an X-ray shielding effect for preventing cross-talk of X-rays leaking from the substrate and has a high light reflection factor and a high X-ray attenuation rate. However, since it is known that the influence of X-ray crosstalk passing through the channel-direction separation layer 13 or the slice-direction separation layer 14 is relatively small, a material similar to the light reflection material of the upper surface light reflection layer 10 is used. There is no problem in characteristics even if is used.

In FIG. 1B, both end faces in the channel direction of the X-ray detecting element array 8 are covered with a light reflecting layer 15. In FIG. 1C, guide members 9 are attached to both ends of the X-ray detection element array 8 in the slice direction. The guide members 9 are closely attached to the side surfaces of the scintillator 5 of the X-ray detection elements 7 at both ends in the slice direction, and are fixed to the upper surface of the printed circuit board 1 with an adhesive or the like. The surface of the guide member 9 which is in close contact with the scintillator 5 is subjected to a process for increasing the light reflectance. Alternatively, the guide member 9 itself may be made of a material having a high light reflectance.

As described above, by covering the periphery of the X-ray detecting element array 8 with the light reflecting layer 15 and the guide member 9, the scintillators 5 of all the X-ray detecting elements 7 constituting the X-ray detecting element array 8 are vertically and horizontally. (In the channel direction and the slice direction), they are separated in a grid pattern, and the top and side surfaces thereof are coated with a light reflecting material to form a closed structure.

As will be described in detail in an embodiment of the manufacturing method described later, the guide member 9 has a step portion on the side facing the scintillator 5, and the step surface and the uppermost surface form a light reflecting layer. It becomes a reference plane for the case. That is, the light reflecting material is filled in two times, the first filling uses the step surface, and the second filling uses the top surface. In the example of FIG. 1C, the upper surface light reflecting layer 10 is formed up to the height of the uppermost surface of the guide member 9.

Next, an embodiment of a method for manufacturing an X-ray detecting element array according to the present invention will be described with reference to FIG. In FIG. 2, FIG. 2 (a) shows parts to be prepared, and FIGS.
(G) shows Step 1 to Step 6, respectively.

FIG. 2A shows the parts to be prepared. Before entering step 1, the scintillator plate 6 and the printed circuit board 1 are prepared. The required number of silicon photodiodes 2 are placed on the upper surface of the printed circuit board 1 at the position where the X-ray detecting element array 8 is formed.
A photodetector array (silicon photodiode array) 3 is formed. The width of the scintillator plate 6 in the channel direction is set to be larger than the width of the photodetector array 3 in the channel direction (the width of the printed circuit board 1).
The large width dimension of the scintillator plate 6 is processed in a later step so as to match the width dimension of the photodetector array 3.

FIG. 2B shows the step 1. In step 1, a scintillator plate 6 is bonded onto the photodetector array 3 on the printed circuit board 1 with a transparent adhesive 4. The layer of the transparent adhesive 4 has a uniform thickness. If the thickness of the adhesive layer 4 varies depending on the location, the light transmittance varies depending on the location,
The light emitted by the scintillator 5 cannot be correctly received by the silicon photodiode 2. In order to form the adhesive layer 4 to have a uniform thickness, after bonding the scintillator plate 6 and the photodetector array 3, a uniform load may be applied from above until the transparent adhesive 4 is sufficiently cured. Good. In addition, foreign substances such as air bubbles and dust are prevented from entering the adhesive layer 4.

In the above-mentioned bonding operation, the photodetector array 3 and the scintillator plate 6 are aligned so that both ends of the scintillator plate 6 in the channel direction are almost evenly wider than the width of the photodetector array 3 in the channel direction. Slightly travel, and in the slice direction, both ends of the scintillator plate 6 in the slice direction are
To the length in the slice direction.

FIG. 2C shows the step 2. In FIG. 2C, the upper figure is an external view, and the lower figure is a cross-sectional view. In step 2, a slice direction separation groove 12 is formed in the scintillator plate 6. The slice direction separation groove 12 is formed vertically until it reaches a position at a predetermined depth from the upper surface of the scintillator plate 6. Normally, the depth of the slice direction separation groove 12 is a depth that almost reaches the photodetector array 3. However, in some cases, a groove depth that does not reach the light detection element array 3, that is, a groove depth halfway through the thickness of the scintillator plate 6 may be selected. For example, when a signal extraction pattern is wired at the position of the photodetector array 3 where the slice direction separation groove 12 is formed, if the groove reaching the photodetector array 3 is formed, the signal extraction pattern may be cut. There is. However, in any case, it is important that all the slice direction separation grooves 12 have the same groove depth. If there is a variation in the groove depth, a variation in the output of each X-ray detection element in the slice direction occurs, which causes deterioration in the image quality of the CT image.

It is important that the width of the slice-direction separation groove 12 is set to an appropriate width. When the groove width is large, transmission of light to adjacent X-ray detection elements in the slice direction can be sufficiently reduced, but conversely, the area of the scintillator 5 of each X-ray detection element increases the groove width. Since the size of the scintillator 5 becomes smaller, the effective light emitting area of the scintillator 5 becomes narrower, and the X-ray detection efficiency decreases. When the groove width is small, the effective light emitting area can be enlarged, but the light transmission to the adjacent X-ray detecting element in the slice direction increases.

It is important that the slice direction separation grooves 12 are all formed in parallel. Slice direction separation groove
If 12 are not formed in parallel, the output of the X-ray detection element will vary between channels, which will cause deterioration of the image quality of the CT image.

The number and position of the slice direction separation grooves 12 are determined based on the target performance specifications of the X-ray detector, and are set so as to match the ordinary light detection element array 3. The number is one or more. When there are a plurality of slices, it is important that all the slice direction separation grooves 12 are arranged in parallel, but they need not be arranged at equal intervals, and may be unequal intervals in some cases. Figure
In the case of 2 (b), three slice direction separation grooves 12 are arranged at equal intervals. The position of the slice direction separation groove 12 is set to coincide with the slice direction boundary position of the photodetector.

FIG. 2D shows Step 3. In FIG. 2D, the upper figure is an external view, and the lower figure is a cross-sectional view. In step 3, two guide members 9 are bonded to both ends of the scintillator plate 6 in the slice direction. The material of the guide member 9 is selected from metals and ceramics. Since the surface of the guide member 9 which is in contact with the scintillator plate 6 needs to function as a light reflecting layer, the guide member 9 has a white color with a high light reflectance, not a black color that absorbs light. Is good. For this reason, a white material such as titanium dioxide is applied as a light reflecting material on the surface of the guide member 9 which is in contact with the scintillator plate 6,
The guide member 9 itself is made of a white material. This is because the light emitted by the scintillator is effectively used without escaping to the outside.

FIG. 3 shows the details of step 3. FIG. 3 (a), FIG.
3 (c) is a cross-sectional view, FIG. 3 (b) is a top view, FIG. 3 (a) is a cross-sectional view in the process of mounting the guide member 9, and FIG. 3 (c) is a cross-section after the guide member 9 is mounted. FIG. As shown in the figure, the guide member 9 has a stepped shape on the side facing the scintillator plate 6. The step surface and the uppermost surface of the guide member 9 serve as reference surfaces when a reflective layer is formed in a later step. Figure
In FIG. 3A, assuming that the outer height of the guide member 9 is A and the height of the inner step surface is H, the outer height A and the height H of the step surface are the scintillator plate 6 and the silicon photodiode. The height is set to be larger than the height h of the portion where 2 is bonded. The difference d = A−h between the outer height A of the guide member 9 and the thickness h (hereinafter abbreviated as the thickness of the scintillator plate or the like) including the silicon photodiode 2 in the scintillator plate 6 is finally the scintillator 5 This is the thickness of the upper surface light reflecting layer 10 formed on the upper surface.

The thickness d of the upper surface light reflecting layer 10 is determined by the scintillator
The thickness is set to a thickness necessary for preventing the light emitted in step 5 from leaking out. In this embodiment, the upper surface light reflecting layer 10 is formed in two steps as described below, the first time it is formed up to the height H of the step surface inside the guide member 9, and the second time the guide member It is formed up to 9 external height A. However, the number of times is not limited to two, and may be one.

Further, the width B of the guide member 9 is not particularly limited, but it is sufficient if the width B can secure a sufficient adhesive strength when the guide member 9 is adhered to the printed circuit board 1. Further, the width S of the inner step surface may be any width as long as the pressure plate 21 can be placed in the next step 4.

The adhesive for adhering the guide member 9 to the printed board 1 has a good affinity for the guide member 9, the scintillator plate 6, the photodetector array 3, and the printed board 1, and has a sufficient adhesive strength. The one that does not cause deterioration due to is preferred. This adhesive may be the transparent adhesive 4 used for bonding the scintillator plate 6 and the photodetector array 3 in step 1.

Regarding the bonding position of the guide member 9, see FIG.
As shown in (b), the outer side surfaces G1 and G2 of the guide member 9 are adhered so as to be parallel to the center lines M1 to M3 of the slice direction separation groove 12. At this time, bonding is performed such that no gap is formed between the end surface of the scintillator plate 6 and the inner side surface of the guide member 9. If a gap is formed in this portion, it causes leakage of light from the scintillator, and becomes one of the causes of the variation in sensitivity of the X-ray detection element.

Further, it is important that the step surfaces S2 of the two guide members 9 are both in the same plane and are parallel to the upper surface S1 of the scintillator plate 6, respectively. This is because the step surface S2 of the two guide members 9 becomes an important reference surface when the light reflecting layer 10 is formed on the upper surface of the scintillator plate 6 in the next step 4.

Next, another embodiment relating to the mounting position of the guide member 9 is shown in FIG. 4A is a sectional view, and FIG. 4B is a top view. In the embodiment of FIG.
At both ends of the scintillator plate 6 in the slicing direction in the slicing direction, the guide members 9 are fixed in close contact with each other so that there is no gap, but in this embodiment, the guide members 9 are provided between the both end surfaces of the scintillator plate 6 and the guide members 9. The guide member 9 is bonded to the printed board 1 with a gap 16 having a width Y provided. In the case of the present embodiment, when filling the slice direction separation groove 12 with the light reflecting material in the step 4, the gap 16 is also filled with the light reflecting material. As a result, the same effect as in the case of the embodiment of FIG. 3 where the white guide member (or the guide member having a white surface treatment) 9 is closely attached to both end surfaces of the scintillator plate 6 can be obtained. There is no particular limitation on the width Y of the gap 16, but it is preferable that the width Y of the two gaps 16 be the same.

FIG. 2E shows Step 4. In FIG. 2E, the upper figure is an external view, and the lower figure is a sectional view. In step 4, the upper surface reflection layer 10 on the upper surface of the scintillator plate 6,
The slice direction separation layer 14 is formed in the slice direction separation groove 12. Since the purpose of the light reflecting material forming the upper surface light reflecting layer 10 on the upper surface of the scintillator plate 6 and the slice direction separating layer 14 is usually the same, the same light reflecting material is used. However, different light reflecting materials may be used for the upper surface light reflecting layer 10 and the slice direction separating layer 14. In this case, the formation of the light reflecting layer is performed twice. Uniform top light reflection layer 10
In order to form the light reflection layer 14 and also to form a uniform light reflection layer 14 in the slice direction separation groove 12, the pressing method described below is appropriate. This pressing method is a method in which a liquid light reflecting resin 20 is dropped on the upper surface of the scintillator plate 6 and a uniform load is applied from above by the pressing plate 21 to form a uniform light reflecting layer film.
In the light reflecting resin 20 used here, it is necessary to pay sufficient attention so that air bubbles and foreign substances are not mixed.

The details of the step 4 when the pressurizing method is used will be described with reference to FIGS. Step 4 includes Step 4.1 shown in FIG. 5, Step 4.2 shown in FIG. 6, and Step 4.3 shown in FIG.
Divided into two sub-processes. 5A is a top view, and FIG. 5B is a cross-sectional view. In step 4.1 shown in FIG. 5, the light reflecting material resin 20 is dropped on the central portion of the upper surface of the scintillator plate 6 so as to be linearly distributed in the direction perpendicular to the slice direction separating groove 12. The distribution of the dropped light-reflecting material resin 20 is such that when the light-reflecting material resin 20 is expanded by pressing in the next step 4.2, the light-reflecting material resin 20 enters the slice direction separating groove 12 and the scintillator plate 6 This is for allowing the light reflecting material resin 20 to flow from the central portion of the upper surface toward the end. In this way, since the light reflecting material resin 20 flows in while pushing out the air in the slice direction separation groove 12, it becomes possible to fill the slice direction separation groove 12 without trapping any air bubbles. .

The amount of the light reflecting material resin 20 dropped is determined by the upper surface of the scintillator plate 6 and the slice direction separating groove 1.
The amount is set to be larger than the net amount of the light reflecting material filled in 2, for example, 1.5 to 2 times. This is more than the net amount in order to spread the light-reflective resin 20 evenly and uniformly to every corner of the scintillator plate 6 when applying pressure in step 4.2 to spread the light-reflective resin 20. Need to be dropped. In order to drop the light reflecting material resin 20, a cylinder having an appropriate inner diameter may be used.

FIG. 6 is a sectional view showing step 4.2. Step 4.
In 2, the light reflecting material resin 20 is uniformly pressed from above by the pressing plate 21. Regarding the size of the pressure plate 21, the width W is the same as the width W of the scintillator plate 6, the length L is larger than the length V of the scintillator plate 6, and the step surfaces of the guide members 9 at both ends of the scintillator plate 6 The length should fit into the part of S2. Assuming that the width of the step surface S2 is S, the length L of the pressing plate 21 is
L = V + 2S may be set.

As for the pressing, the light reflecting material resin 20 is slowly pressed while keeping the pressing plate 21 horizontal.
Pressure is applied until the pressure plate 21 reaches the step surface S2 of the guide member 9. Excess light reflecting material resin 20 leaked from the slice direction separation groove 12 and the like is quickly wiped off, and the light reflecting material resin 20 is cured while a sufficient load is applied from above the pressing plate 21.

FIG. 7 is a sectional view showing step 4.3. Step 4.
In 3, after the light reflecting material resin 20 is sufficiently cured, the pressure plate 21 is peeled off from the light reflecting material resin 20 and removed. This operation is performed slowly so that the guide member 9 and the pressure plate 21 are not damaged.

FIG. 2F shows Step 5. In step 5, a channel direction separation groove 11 for separating the scintillator plate 6 in the channel direction is formed. The channel direction separation groove 11 is grooved at a depth from the upper surface light reflection layer 10 formed on the upper surface of the scintillator plate 6 to reach the photodetector array 3. The position of the channel direction separation groove 11 is set so as to coincide with the boundary position of the photodetector 2 in the channel direction. In Step 5, after a sufficient time has elapsed after Step 4 is completed, after confirming that the upper surface light-reflective layer 10 formed in Step 4 has been sufficiently cured, a groove processing operation is performed. Also, this process
In 5, by forming the channel direction separation groove 11 at the end of the scintillator plate 6 in the channel direction, the width of the scintillator plate 6 is processed so as to match the width of the photodetector array 3.

If the groove processing is performed before the upper surface light reflection layer 10 is sufficiently cured, the still soft light reflection material resin 20 enters the channel direction separation groove 11, causing the sensitivity unevenness of each channel and causing the characteristic variation. Cause it to occur. The depth of the channel direction separation groove 11 does not need to be uniform in all the grooves, but needs to reach the photodetection element array 3 sufficiently. Without the depth of the channel direction separation groove 11 reaching the photodetector array 3,
If the scintillator plate 6 is not completely separated, sensitivity variations will occur between channels.

Regarding the groove width of the channel direction separation groove 11, it is better to reduce the width of the groove which cannot be used effectively in order to increase the efficiency of use of X-rays. It is important to select an appropriate groove width because so-called crosstalk of light, which leaks through the direction separation groove 11 and cannot be performed correctly in each channel, occurs. Regarding the length of the channel direction separation groove 11, the scintillator plate 6
It is important to completely separate the channels from each other, and for this purpose, a groove may be formed up to the guide member 9 bonded to both ends of the scintillator plate 6.

FIG. 2G shows the step 6. In FIG. 2 (g), the upper figure is an external view, and the lower figure is a sectional view. In Step 6, the channel direction separation groove 11 is filled with the light reflecting material resin 20. The filling method of the light reflecting material resin 20 is the same as the above-described step 4
Is performed in the same manner as described above.

Hereinafter, the details of Step 6 will be described with reference to FIGS. Step 6 includes Step 6.1 shown in FIG.
, A step 6.3 shown in FIG. 10, and a step 6.4 shown in FIG.

FIG. 8A is a top view of step 6.1, and FIG.
Is a cross-sectional view of a step 6.1. In step 6.1, first, X
Guide plates 22 are fixed to both ends of the line detection element array 8 in the channel direction. When the guide plate 22 fills the channel direction separation groove 11 with the light reflecting resin 20 in step 6.3,
The role of a guide frame for filling the light reflecting material resin 20 into the channel direction separation grooves 11 at both ends of the scintillator plate 6 in the channel direction is also assumed. An appropriate length P of the guide plate 22 is a distance between the two guide members 9,
That is, it is slightly longer than V + 2B (the length of the scintillator plate + the width of the guide member × 2). The appropriate height Q of the guide plate 22 is such that the height dimension of the guide member 9 is A, and the printed board 1
When the thickness dimension of C is C, Q = A + C.

The guide plate 22 is free from warpage or surface flaws, and a suitable material is ceramic or the like. The two guide plates 22 having the shapes and dimensions as described above are fixed to both ends of the scintillator plate 6 in the channel direction such that the ridges thereof coincide with the reference surface S3 (uppermost surface) of the guide member 9.

FIG. 9 shows step 6.2. FIG. 9A is a top view, and FIG. 9B is a cross-sectional view. In step 6.2, the light reflecting material resin 20 is dropped at the center of the upper surface of the scintillator plate 6 so as to be linearly distributed in the direction perpendicular to the channel direction separation groove 11. The reason why the light reflection material resin 20 is dropped in the direction perpendicular to the channel direction separation groove 11 is that, when the light reflection material resin 20 is pressed and spread, as in the case of the step 4, the channel direction separation groove is formed. This is because the light reflecting material resin 20 flows to the end of the groove without trapping air bubbles while sequentially expelling the air in 11. Light-reflective material resin 20 to be dropped
Is the total thickness of the upper surface light reflection layer 10 formed on the upper surface of the scintillator plate 6 and the light reflection material resin 20 required to form the channel direction separation layer 13 formed in the channel direction separation groove 11. More than the net amount, for example, 1.5 to 2 times.

FIG. 10 is a sectional view showing step 6.3. Process
In 6.3, the light reflecting material resin 20 is uniformly pressed from above by the pressing plate 21. The pressure plate 21 used here may be the same as that used in step 4, but the length of the pressure plate 21 used in step 6.3 is set to V + 2B and slightly longer than that used in step 4. . Here, the length of the scintillator plate 6 is V, and the width of the guide member 9 is B.

As for the pressing, the pressing is performed slowly and uniformly until the pressing plate 21 reaches the reference surface S3 of the guide member 9. Excess light reflecting material resin 20 leaked from the channel direction separation groove 11 or the like is quickly wiped off, and the light reflecting material resin 20 is cured while a constant load is applied.

FIG. 11 is a sectional view showing a step 6.4. Process
In 6.4, after the light reflector resin 20 is sufficiently cured,
The pressure plate 21 and the guide plate 22 are peeled off from the light reflecting material resin 20 and removed. As in the case of the step 4, the pressing plate 21, the guide member 9 and the guide plate 22 are not damaged, and the light reflecting layer 15 on the upper surface of the scintillator 5 and the light reflecting layer 15 on the side surface of the scintillator 5 are not damaged. Carefully, the pressure plate 21 and the guide plate 22 are peeled off slowly.

According to the manufacturing method of the above steps 1 to 6,
An X-ray detection element array in which a plurality of X-ray detection elements are arranged in the channel direction and the slice direction, respectively, is manufactured. By arranging this X-ray detecting element array in a polygonal shape on an arc centered on the focal point of the X-ray tube as in FIG. 13, the X-ray detector for the X-ray CT apparatus of the present invention (multi-slice type X-ray detecting apparatus) Container) is obtained.

The X-ray detector for an X-ray CT apparatus according to the present invention
It can be housed in a X-ray detector container and easily incorporated into an X-ray CT apparatus like a conventional product. By applying the X-ray detector of the present invention to an X-ray CT apparatus, an X-ray CT apparatus capable of acquiring a plurality of high-quality CT images in one scan can be realized.

[0079]

As described above, according to the present invention, X
By dividing the scintillator constituting the X-ray detection element of the X-ray detection element array constituting the X-ray detector from one scintillator plate, by taking a structure to form a uniform light reflection layer on the top and side surfaces of the scintillator, Variations in output characteristics caused by differences in the sensitivity of the scintillator due to individual X-ray detection elements and differences in light reflectance on the top and side surfaces of the scintillator are eliminated, and high performance and
A highly accurate X-ray detector for an X-ray CT apparatus can be obtained.

Further, according to the manufacturing method of the present invention, the light reflecting material is pressed to form the light reflecting layer, so that the light reflecting layer having a uniform thickness is formed on the upper surface and the side surface of the scintillator. Can be done easily.

Also, by applying the X-ray detector of the present invention to an X-ray CT apparatus, C
It is possible to increase the number of T images and improve the quality of CT images.

[Brief description of the drawings]

FIG. 1 is a first embodiment of an X-ray detector for an X-ray CT apparatus according to the present invention.

FIG. 2 is an embodiment of a method for manufacturing an X-ray detection element array according to the present invention.

FIG. 3 is a view showing details of a step 3 (attachment of a guide member).

FIG. 4 is a view showing another example of step 3.

FIG. 5 is a view showing a step 4.1 (dropping of a light reflecting material resin).

FIG. 6 is a view showing a step 4.2 (pressing a light reflecting material resin).

FIG. 7 is a view showing a step 4.3 (peeling of a pressure plate).

FIG. 8 is a view showing step 6.1 (attachment of a guide plate).

FIG. 9 is a view showing a step 6.2 (dropping of a light reflecting material resin).

FIG. 10 is a view showing a step 6.3 ((Pressure of light reflecting material resin));

FIG. 11 is a view showing a step 6.4 (peeling of a pressure plate and a guide plate).

FIG. 12 is a schematic diagram of a multi-slice X-ray detector.

FIG. 13 is a schematic diagram showing the entire structure of a single-slice X-ray detector.

FIG. 14 is an external view and a cross-sectional view of an X-ray detection element array included in a single-slice X-ray detector.

[Explanation of symbols]

1,120 ... 2 Printed circuit board 2,117 ... Silicon photodiode (photodetector) 3 ... Silicon photodiode array (photodetector array) 4,121 ... Transparent adhesive (adhesive layer) 5,116 ... Scintillator (Scintillator element) 6 ... Scintillator plate 7, 115 ... X-ray detection element 8, 112 ... X-ray detection element array 9 ... Guide member 10 ... Top light reflection layer 11, 118 ... Channel direction separation groove 12 ... Slice direction separation groove 13 … Channel direction separation layer 14… slice direction separation layer 15… light reflection layer 16… gap 20… light reflection material resin 21… pressure plate 22… guide plate 101… X-ray tube 102… subject 103… multi-slice X-ray detection Detector 104 X-ray beam 105 X-ray detector array 110 Single-slice X-ray detector 111 Light reflection film 113 X-ray detector container 119 Metal plate 122 Photodetector array 123 Scintillator plate

Claims (3)

[Claims] An X-ray combining a scintillator that detects incident radiation and emits light, and a photodetector that receives an emission from the scintillator and generates an output signal corresponding to the radiation dose detected by the scintillator. An X-ray CT apparatus in which a plurality of X-ray detection element rows in which a plurality of detection elements are arranged in a substantially arc shape (this arrangement direction is hereinafter referred to as a channel direction) are arranged in a plurality of rows in a direction orthogonal to the channel direction (hereinafter referred to as a slice direction). In the X-ray detector for use, a channel direction separation groove and a slice direction separation groove for separating each X-ray detection element in the channel direction and the slice direction are provided in the scintillator portion, and the depth of the separation groove is set in the photodetection element. The depth is set to almost reach, and light is applied to the upper surface of the scintillator of each X-ray detector, the channel direction separation groove and the slice direction separation groove. An X-ray detector for an X-ray CT apparatus, wherein a light reflecting layer is formed by coating or filling a reflecting material. 2. A first step of adhesively fixing a scintillator plate on an upper surface of a photodetector array formed by arranging a plurality of photodetectors in a channel direction and a slice direction on a printed circuit board, and slicing the photodetector. A second step of forming a slice-direction separation groove of a depth until reaching the photodetector array in the scintillator plate corresponding to each slice boundary position in the direction, and a height reference at both ends of the scintillator plate in the slice direction. A third step of bonding a guide member for securing a surface, and based on the guide member,
A fourth step of filling the upper surface of the scintillator plate and the slice direction separating groove with a light reflecting material to form a light reflecting layer and a slice direction separating layer on the upper surface of the scintillator plate, and each channel boundary in the channel direction of the photodetector. Fifth step of forming a channel direction separation groove in the scintillator plate corresponding to the position until the light detection element array is almost reached, and, based on the guide member, filling the channel direction separation groove with a light reflecting material, And a sixth step of forming a channel direction separation layer. 3. An X-ray transmitted through a subject using an X-ray detector.
2. An X-ray CT apparatus for detecting a line to obtain a CT image, wherein the X-ray detector is the X-ray detector for an X-ray CT apparatus according to claim 1.