JPH04240442A - X-ray detector for x-ray ct apparatus - Google Patents

Abstract

PURPOSE:To provide an X-ray detector for an X-ray CT apparatus with a high measuring accuracy possible by keeping the heights of X-ray incoming surfaces of scintillators in X-ray detector arrays arranged in plurality adjacent to each other in a detector case constant without variations to lower variations in sensitivity characteristic. CONSTITUTION:Spacers 15 which are fixed tight on corresponding mounting surfaces are arranged on respective X-ray detector arrays mounting positions within detector cases 2 and 2'', an adhesive varying in thickness optionally with a pressing pressure is applied between the spacers 15 and the X-ray detector arrays. When the X-ray detector arrays or the spacers 15 are pressed with pressing devices 22 and 23 having a recess with a specified depth dimension H, a height dimension to the X-ray incoming surface of a scintillator 9 from a surface of mounting the X-ray detector arrays on the detector 2' is developed to a specified constant value H with the varying of the thickness of the adhesive.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to an X-ray detector for an X-ray CT apparatus, and in particular, variations in sensitivity characteristics between a large number of X-ray detection element arrays arranged adjacently in a detector case. The present invention relates to an X-ray detector suitable for obtaining high measurement accuracy.

0002

2. Description of the Related Art A conventional X-ray detector for an X-ray CT apparatus will be explained with reference to FIGS. 6 to 9. 6 is an overall perspective view showing the external appearance of the X-ray detector, FIG. 7 is a sectional view taken along line VII-VII in FIG. 6 showing the polygonal arrangement of the X-ray detection element array, and FIG.
8(a) is a perspective view showing the external appearance, and (b) is a diagram VIIIb-VII of FIG. 8(a).
The Ib detailed cross-sectional view and FIG. 9 are explanatory diagrams of the manufacturing process of the X-ray detection element array.

As shown in FIGS. 6 and 7, the X-ray detector includes a detector case 2 formed in an arc shape centered on the focal point of the X-ray tube 1, and a detector case 2 at the X-ray entrance to remove scattered radiation. A collimator 3 provided, a plurality of X-ray detection element arrays 4 arranged in a polygonal manner with respect to the focal point of the X-ray tube 1 in the detector case 2, and incident X converted by each X-ray detection element array 4 It is composed of a connector 5 and the like for transmitting line signals to an external amplifier. 6 is the subject. Furthermore, as shown in FIGS. 8(a) and 8(b), the X-ray detection element array 4 is a multi-channel structure in which a plurality of light receiving elements are arranged in parallel at a predetermined pitch on a substrate 7 via an adhesive 10. The photoelectric conversion element 8, the scintillator 9, which is bonded and fixed to each other via a transparent adhesive 11 and emits light according to the intensity of incident X-rays, and the photoelectric conversion element 8 are separated from each other. Partition plate 13 inserted into groove 12 formed in
It is composed of etc. The photoelectric conversion element 8 is, for example, P
A silicon photodiode with an IN type structure is used, and both ends of the partition plate 13 in the longitudinal direction are adhesively fixed to the photoelectric conversion element 8 or the substrate 7 with an adhesive 14.

Next, the manufacturing process of the detection element portion of the X-ray detection element array 4 will be explained with reference to FIG. First, Figure 9 (
Adhesive 1 shown in FIG. 8(b) is applied onto the substrate 7 as shown in a).
A silicon photodiode 8 that constitutes a light-receiving element for several channels is bonded using a silicon photodiode 8, and a plate-shaped scintillator 9 that is processed to a predetermined thickness is placed on the bonded silicon photodiode 8. Using a transparent adhesive 11 with high light transmittance as shown in FIG. 8(b), the photodiode 8 is placed in the state shown in FIG. 9(b) so that its position corresponds accurately to the sensitive part of each light receiving element. Glue. In this case, the area of the silicon photodiode 8 is as shown in FIG.
As shown in (b), the area is slightly larger than the area of the scintillator 9. Next, as shown in FIG. 9(c), a plurality of grooves 12 are formed in parallel to the scintillator 9, and each channel of the silicon photodiode 8 is separated. Groove 12
The processing is continued until the bottom of the groove 12 reaches a depth that reaches the silicon photodiode 8, as shown in FIG. 8(b). Then, the partition plate 13 is inserted into the groove 12 processed as shown in FIG. 9(d), and both ends of the inserted partition plate 13 are fixed with adhesive (14 shown in FIG. 8) to complete the process.

[0005] The X-ray detection element array 4 completed by the above process is arranged in a plurality of polygons adjacent to the focus of the X-ray tube 1 in the detector case 2, and covers the main part of the X-ray detector. Configure. In this case, although not shown, on the X-ray incident side surface of the X-ray detection element array 4,
In order to efficiently make the light emitted from the scintillator 9 incident on the silicon photodiode 8, a light reflecting film made of a material with high light reflectivity such as a polyester film on which aluminum is vapor-deposited is provided.

[0006]

[Problems to be Solved by the Invention] In the conventional X-ray detector described above, when a plurality of X-ray detection element arrays 4 are arranged in the detector case 2, the surface 9a of each scintillator 9 on the X-ray incident side The relative positional relationship between the light reflecting film and the above-mentioned light reflecting film installed on the surface 9a, that is, the state of contact between the two, the gap between the two, etc., differed between the X-ray detection element arrays 4. In this case, since the thickness dimensions of the silicon photodiode 8 and the scintillator 9 are substantially constant, it can be seen that the cause of the difference is due to the layer thickness of the adhesives 10 and 11. The extent to which the different amounts change is determined by how uniform the layer thicknesses of the adhesives 10 and 11 are. By the way, if the layer thicknesses of the adhesives 10 and 11 are not uniform as described above and the height of the surface 9a of the scintillator 9 is different between each X-ray detection element array 4, the surface 9a and the light reflecting film may be different from each other. The relative positional relationship between the X-ray detection element arrays 4 varies. This variation causes the sensitivity characteristics of the detected X-rays to vary and makes it impossible to obtain a good quality image.
It is required that the heights of the electrodes be arranged with an accuracy of approximately 10 μm. However, the layer thickness of the adhesives 10 and 11 can usually be controlled to an accuracy of only a few tens of micrometers, making it technically difficult to meet the above requirements.

[0007] In view of the problems of the above-mentioned prior art, the present invention
The height of the surface 9a of the scintillator 9 of each of the X-ray detection element arrays arranged in large numbers adjacent to each other in the detector case 2 is set to a constant height without variations, reducing variations in sensitivity characteristics, and increasing the height. An object of the present invention is to provide an X-ray detector for an X-ray CT apparatus that can obtain measurement accuracy.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a multi-channel photoelectric conversion element in which a plurality of light receiving elements are arranged in parallel at a predetermined pitch on a substrate via an adhesive; A scintillator that emits light according to the intensity of incident X-rays, which is fixed to the photoelectric conversion element by adhering to each other via an adhesive, and a groove for separating each channel formed between each channel of the photoelectric conversion element. In an X-ray detector for an X-ray CT apparatus in which a plurality of X-ray detection element arrays each including an inserted partition plate are arranged adjacently in a detector case, each X-ray detection element array in the detector case A spacer that is closely fixed to the mounting surface is provided at the array mounting position, and an adhesive whose thickness can be arbitrarily changed by pressing is applied between the spacer and the X-ray detection element array. Alternatively, when the spacer is pressed through a pressing tool having a concave portion with a predetermined depth dimension, the height dimension from the mounting surface of each X-ray detection element array to the detector case to the X-ray incident side surface of the scintillator is , the adhesive is formed into a predetermined constant size by changing the thickness of the adhesive.

[0009]

[Operation] With the above configuration, the adhesive stuck between the spacer and the X-ray detection element array is pressed by a pressing tool having a recess with a predetermined depth dimension, and the adhesive is pressed down to its thickness. can change arbitrarily, so the height dimension from the mounting surface of each X-ray detection element array arranged in the detector case to the X-ray incident side surface of the scintillator is The scintillator at the position is also formed to have a predetermined constant dimension corresponding to the depth dimension of the recess of the pressing tool. Therefore, the surface of each scintillator on the X-ray incident side has a constant height with no variation, and
By reducing variations in sensitivity characteristics between line detection element arrays,
It becomes possible to obtain high measurement accuracy.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 to 5. In the figure, the same reference numerals as in FIGS. 6 to 9 indicate the same things. FIG. 1 is a side sectional view of the X-ray detector in the channel separation direction in the first embodiment, and FIG.
I sectional view, FIG. 3 is a diagram showing the usage state of the pressing tool, (a)
4 is a diagram showing the state before use, (b) is a diagram showing the state in use, FIG. 4 is a side sectional view in the channel separation direction of the second embodiment, and FIG. 5 is a diagram showing the state in which the pressing tool in FIG. 4 is used. ,(a)
(b) is a diagram showing the state before use, and (b) is a diagram showing the state after use.

In the figure, reference numeral 15 denotes a flat spacer bonded to the substrate 7 via an adhesive 16. The X-ray detecting element array 4 is arranged in a polygonal manner at a mounting position between the X-ray detecting element array 4 and the detector case 2' provided in the detector case 2', and is closely fixed by screws 17. Reference numeral 18 denotes a light reflecting plate arranged so as to be in close contact with the scintillator surface 9a of each X-ray detection element array 4 arranged in the detector cases 2, 2'. They are formed from mirror-treated aluminum thin plates, and are arranged in a polygon shape corresponding to the arrangement of the X-ray detection element array 4. and,
The light reflecting plate 18 is pressed against the scintillator surface 9a by the collimator 3 and the detector cases 2, 2' via the packing material 19 and the light shielding plate 20. In this state, the height H from the mounting surface of each X-ray detection element array 4 to the detector case 2' to the surface 9a of the scintillator 9 is the same even if the layer thickness of the adhesives 10 and 11 is uneven. They are also formed to have a constant and equal height by a method using a pressing tool shown in FIG. 3, which will be described later. Therefore, the relative positional relationship between the surface 9a of the scintillator 9 of each X-ray detection element array 4 and the light reflection plate 18, that is, the state of contact between the two or the size of the gap between the two, is made uniform to a constant state. Become.

Next, in FIG. 3, 21 is a smooth surface 2
A spacer 15 is placed on the surface 21a of the surface plate 1a, and an adhesive 16 is adhered to the upper surface of the spacer 15. As the adhesive 16, a two-component mixed epoxy adhesive or the like is used, which has a viscosity that does not run away immediately when applied, and which exhibits little volume change (shrinkage) when cured. 22 is a pressing tool that presses the scintillator surface 9a;
A recess is formed at a predetermined depth H, that is, a height H from the mounting surface of the X-ray detection element array 4 to the detector case 2' to the surface 9a of the scintillator 9.

When the scintillator surface 9a is pressed by the pressing tool 22 in the state shown in FIG. 3(a), the adhesive 16 is pressed by the substrate 7 of the X-ray detection element array 4, and as shown in FIG. 3(b), The total thickness of the height h of the X-ray detection element array 4, the thickness of the adhesive 16, and the thickness of the spacer 15 can be changed arbitrarily until the total thickness reaches a predetermined depth H of the pressing tool 22. Therefore, even if the height dimension h of each X-ray detection element array 4 is non-uniform due to variations in the thickness of the adhesives 10 and 11, this non-uniform dimension is absorbed by the change in the thickness of the adhesive 16. , the total thickness is the predetermined depth H of the pressing tool 22
is uniformized to a constant size equal to . Therefore, the surface 9a of the scintillator 9 of each X-ray detection element array 4 and the light reflection plate 1
The relative positional relationship with respect to X-ray detecting element array 4 is also uniformized to a constant state, and it becomes possible to make the sensitivity characteristics of each X-ray detecting element array 4 uniform and without variations.

FIG. 4 is a diagram showing a second embodiment corresponding to FIG. 1, in which the X-ray detection element array 4 in FIG. This is a configuration example in which an X-ray detection element array 4 formed at a constant and equal height by a method using a pressing tool shown in FIG. 5, which will be described later, is attached to the detector case 2 with screws 24.

FIG. 5 shows the X-ray detection element array 4 shown in FIG. 4 upside down. In FIG. 5, reference numeral 23 denotes a pressing tool that presses the scintillator surface 9a.
A recessed portion having a height dimension H' up to a is formed.

When the spacer 15 and adhesive 16 are pressed with the pressing tool 23 in the state shown in FIG. 5(a), the adhesive 16
is pressed against the surface of the substrate 7 of the X-ray detection element array 4, and as shown in FIG.
As shown in (b), the thickness can be arbitrarily changed until the concave surface of the pressing tool 23 having the dimension H' comes into contact with the scintillator surface 9a. Therefore, even if the height dimension h of each X-ray detection element array 4 is non-uniform due to variations in the thickness of the adhesives 10 and 11, this non-uniform dimension is absorbed by the change in the thickness of the adhesive 16. The thickness from the surface of the spacer 15, which is the mounting surface to the detector case 2, to the scintillator surface 9a is made uniform to a constant dimension equal to the predetermined depth H' of the pressing tool 23. Therefore, the relative positional relationship between the surface 9a of the scintillator 9 and the light reflection plate 18 of each X-ray detection element array 4 is also uniformized to a constant state, and the sensitivity characteristics of each X-ray detection element array 4 are uniform and uniform. It becomes possible to make it a characteristic.

[0017]

Effects of the Invention As explained above, the X-ray detector for an X-ray CT apparatus of the present invention has a surface area of the scintillator of each X-ray detection element array arranged in a polygonal manner adjacent to each other in the detector case. Since the height can be formed to a predetermined constant dimension from the mounting surface of the X-ray detection element array to the detector case, the relative positional relationship between the scintillator surface and the light reflecting plate installed on the scintillator surface can be adjusted. It becomes possible to make the sensitivity characteristics of each X-ray detection element array uniform and uniform, and it is possible to obtain an X-ray detector with high measurement accuracy.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view in the channel separation direction of an X-ray detector according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG. 1;

FIG. 3 is a diagram showing the state in which the pressing tool is used in the first embodiment, in which (a) is a diagram showing the state before use, and (b) is a diagram showing the state in which it is used.

FIG. 4 is a side sectional view in the channel separation direction of an X-ray detector according to a second embodiment of the present invention.

FIG. 5 is a diagram showing the state in which the pressing tool is used in the second embodiment, in which (a) is a state diagram before use, and (b) is a diagram showing a state in which it is used.

FIG. 6 is an overall perspective view showing the appearance of a conventional X-ray detector.

FIG. 7 is a cross-sectional view taken along VII-VII of FIG. 6 showing a polygonal arrangement of an X-ray detection element array.

FIG. 8 is an explanatory diagram of the configuration of an X-ray detection element array, in which (a) is a perspective view showing the external appearance, and (b) is an VIIIb-
VIIIb is a detailed cross-sectional view.

FIG. 9 is an explanatory diagram of the manufacturing process of the X-ray detection element array.

[Explanation of symbols]

2 Detector case 2' Detector case 4 X-ray detection element array 7 Substrate 8 Photoelectric conversion element (silicon photodiode) 9
Scintillator 9a Surface 10 Adhesive 11 Adhesive 12 Groove 13 Partition plate 15 Spacer 16 Adhesive 18 Light reflecting plate 22 Pressing tool 23 Pressing tool

Claims (1)

[Claims] 1. A multi-channel photoelectric conversion element in which a plurality of light receiving elements are arranged in parallel at a predetermined pitch on a substrate via an adhesive, and the photoelectric conversion element and the photoelectric conversion element are bonded and fixed to each other via an adhesive. an X-ray detection element array consisting of a scintillator that emits light according to the intensity of incident X-rays, and a partition plate inserted into a groove for separating each channel formed between each channel of the photoelectric conversion element, In a plurality of X-ray detectors for an X-ray CT apparatus arranged adjacently in a detector case, a spacer is provided at each X-ray detection element array mounting position in the detector case to be closely fixed to the mounting surface. An adhesive whose thickness can be arbitrarily changed by pressing is applied between the spacer and the X-ray detection element array, and a pressing tool having a concave portion of a predetermined depth is used to press the X-ray detection element array or the spacer. When pressed through the adhesive, the height dimension from the mounting surface of each of the X-ray detection element arrays to the detector case to the X-ray incident side surface of the scintillator becomes a predetermined constant dimension due to a change in the thickness of the adhesive. 1. An X-ray detector for an X-ray CT apparatus, characterized in that the X-ray detector is configured to be formed.