JPH06214036A - Multiple element x-ray detector - Google Patents

Abstract

PURPOSE:To turn each X-ray detecting element in the focus direction of an X-ray tube, linearly arrange X-ray detecting element arrays on the same plane, eliminate the difference in detecting characteristic between the detecting elements, and downsize a detector. CONSTITUTION:The emitted X-ray beam 1 of an X-ray tube 16 is incident to X-ray detecting arrays 10 consisting of a plurality of X-ray detecting elements and linearly arranged on the same plane after transmitted by a subject 15. The arrays 10 convert the incident X-ray into a light having a strength according to intensity by a scintillator 2, and further convert it into a current by a photoelectric converting element 3 to provide an electric signal according to the intensity. The X-ray detecting elements are formed of the scintillators 2 having a determined dimension and elements 3 whose light receiving surfaces make contact with the scintillators, and a bulkhead plate 4 is inserted to a groove radially worked in the focus direction of the X-ray tube 16 to separate them. Thus, each detecting element is turned in the focus direction of the X-ray tube 16, and the difference in X-ray detecting characteristic between the detecting elements in the center of a detector and near the end part is eliminated. Since the arrays 10 are linearly arranged on the same plane, the detector can be downsized when used in a plane scanning type X-ray photographing device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat scan type X-ray imaging apparatus such as a bone mineral quantitative measuring apparatus and a baggage inspection apparatus.
The present invention relates to a multi-element X-ray detector suitable for a line detector.

[0002]

2. Description of the Related Art A conventional multi-element X-ray detector is a multi-channel X-ray detector in which a scintillator and a photoelectric conversion element are combined.
It is configured by arranging a predetermined number of line detection element arrays in a polygonal shape.

This conventional multi-element X-ray detector is shown in FIGS.
Shown in. FIG. 4 is a perspective view showing the whole, and FIG. 5 is VV of FIG.
FIG. 6 is an enlarged view showing a part of FIG.
In these figures, 1 is an X-ray beam, 2 is a scintillator, 3 is a photoelectric conversion element (silicon photodiode),
4 is a partition plate, 5 is an adhesive, 7 is a substrate, 8 is a light reflection plate, and 9
Is a detector case, 10 is an X-ray detection element array, 11 is a collimator, 12 is a connector, 13 is a pressing plate, 14 is packing, 15 is a subject, and 16 is an X-ray tube. In addition,
Reference numeral 100 represents a conventional multi-element X-ray detector.

As shown in FIG. 5, the X-ray beam 1 radiated from the X-ray tube 16 in a fan shape passes through the subject 15 and then enters the X-ray detector 100. X-ray detector 100
The inside of the X is composed of X-ray detection elements of multiple channels.
The line detection element array 10 is linearly arranged when viewed from the X-ray tube 16. In FIG. 6, each X-ray detection element array 1
At 0, the incident X-ray intensity is converted by the scintillator 2 into light having an intensity corresponding to the intensity, and then the light is incident on the photoelectric conversion element 3 to be converted into an electric current to correspond to the incident X-ray intensity. I am getting the electric signal.

One element (X-ray detection element) of the multi-element X-ray detector 100 is a scintillator 2 processed into a predetermined size.
And a photoelectric conversion element 3 combined such that the scintillator 2 and the light receiving surface are in contact with each other.

The material of the scintillator 2 is scintillation efficiency (a value indicating how much incident X-ray energy can be converted into light energy), light transmittance (how much light emitted inside the scintillator 2 is not attenuated). To the light receiving surface of the photoelectric conversion element 3), afterglow characteristics (a value indicating the time until the emission of light in the scintillator 2 disappears after the incident X-ray disappears, and the manner of the phenomenon), etc. BGO, CdWO _4, etc. are usually used.

The photoelectric conversion element 3 has a high conversion efficiency for converting incident light into a current signal, and it is necessary to use a material having high sensitivity in the vicinity of the emission wavelength of the scintillator 2. Diode (S
PD) and the like are commonly used. Further, each X-ray detection element is separated by a partition plate 4 for each channel perpendicularly to the light receiving surface of three rows of photoelectric conversion elements (silicon photodiode array).

In the partition plate 4, the emitted light from the scintillator 2 of each X-ray detecting element leaks into the adjacent channel, and the scattered X-rays from the scintillator 2 generated by the X-rays incident on the scintillator 2 leak into the adjacent channel. This is to prevent this and effectively use the light emission in the scintillator 2 as the output of that channel. This partition plate 4
For example, a material in which the surface of a tungsten or molybdenum plate, which is a material having a high X-ray absorption coefficient, is polished and aluminum is vapor-deposited on the surface to increase the light reflectance is used.

As an example of a method of manufacturing the X-ray detection element array 10, first, a scintillator material processed into a plate having a predetermined thickness and a photoelectric conversion element 3 in which elements for several channels are formed on one wafer, Then, the silicon photodiodes are bonded by using a transparent adhesive 5 having a high light transmittance so that their centers coincide with each other.

Next, the scintillator material and the silicon photodiode 3 are bonded together, and a groove is cut so that the scintillator material is separated for each channel so as to be perpendicular to the light receiving surface of the silicon photodiode 3. .
This groove processing is performed by using the pattern of the signal electrode plate of the silicon photodiode 3 slightly exposed at both ends of the scintillator material as a position reference. Further, the groove depth is set to such a depth that the bottom of the groove reaches the silicon photodiode 3 so that the respective parts of the scintillator material are completely separated as the scintillator 2. Finally, the partition plate 4 is inserted into this groove and both end faces are fixed with an adhesive.

The end channels of the X-ray detector element array 10 are treated so that the element pitches of the channels become equal when the X-ray detector element array 10 is arranged in a polygonal shape. That is, the partition plate 4 having a thickness half that of the partition plate 4 to be inserted in the middle portion of the X-ray detection element array 10 is X.
It is installed on both end faces of the line detection element array 10. Alternatively, the same thing as the partition plate 4 to be inserted in the middle part is installed only on one side, and the side surface where the side surface of the scintillator 2 is exposed without installing the partition plate 4 has a neighboring X-ray when installed in a polygonal shape. The partition plates 4 of the detection element array 10 are in contact with each other so that the element pitch of the end channels is kept the same as the element pitch of the intermediate channels.

[0012]

The conventional multi-element X-ray detector is an arc-shaped multi-element X-ray detector in which the X-ray detection element array 10 is arranged in a polygonal shape.
Therefore, the detector case 9 in which 0 is arranged is processed into an arc shape. Since the surface of the case 9 where the X-ray detection element array 10 is arranged is further subjected to precision processing in a polygonal shape, the processing is complicated and it is difficult to obtain sufficient processing accuracy. Further, it is difficult to obtain sufficient positional accuracy in the alignment during the step of arranging the X-ray detection element array 10.

Further, when the conventional arc type multi-element X-ray detector is mounted instead of an X-ray imaging apparatus of a plane scan type, the shape is larger than that of the linear array of the X-ray detection element array 10. In view of downsizing, a multi-element X-ray detector dedicated to a plane scan X-ray imaging apparatus has been demanded.

However, the linear multi-element X-ray detector may be constructed by linearly arranging the X-ray detection element array 10 mounted on the conventional arc-shaped multi-element X-ray detector as it is. Since each X-ray detecting element is made so as to be separated from the adjacent channel by the partition plate 4 which is perpendicular to the X-ray receiving surface, the X-rays obliquely incident on the channel near the end of the detector 100 are separated by the partition plate 4. There is a problem that the detection output is lowered due to the interruption by the electromagnetic wave and the crosstalk occurs through the partition plate 4 when the incident X-ray is strong. Therefore, the channel near the center of the detector where the incident X-rays are almost directly incident,
There is a problem in that there is a large difference in the X-ray detection characteristics between the channel near the detector end where the incident angle is large and oblique incidence occurs.

An object of the present invention is to reduce the size and cost when used in a plane scan type X-ray imaging apparatus, and to reduce the difference in X-ray detection characteristics between X-ray detection elements (channels). In particular, it is an object of the present invention to provide a multi-element X-ray detector capable of largely eliminating the difference in X-ray detection characteristics between the channel near the center of the detector and the channel near the detector end.

[0016]

The above object is achieved by arranging X-ray detection element arrays in a straight line on the same plane and orienting each X-ray detection element in the focal direction of the X-ray tube.

[0017]

By arranging the X-ray detection element arrays linearly on the same plane, the X-ray detection element array is suitable for a plane scan type X-ray imaging apparatus, and processing accuracy and assembly accuracy can be sufficiently obtained. Will be realized. Further, since each X-ray detecting element (channel) is oriented in the focal direction of the X-ray tube, oblique incidence of X-rays and crosstalk are eliminated, and each X-ray is used when used in a plane scan type X-ray imaging apparatus. The difference in the X-ray detection characteristics between the line detection elements (channels), in particular, the difference in the X-ray detection characteristics between the channel near the center of the detector and the channel near the end of the detector is substantially eliminated.

According to this, particularly when applied to a quantitative analysis device which directly obtains some quantitative value from the X-ray detection amount as seen in a bone mineral quantitative measurement device and the like, the quantitative analysis within the scanning range is performed. The position dependence of the value measurement is eliminated.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a sectional view showing an embodiment of a multi-element X-ray detector according to the present invention, and FIG. 2 is an enlarged view showing a part of FIG.

In these figures, 1 is an X-ray beam, 2
Is a scintillator, 3 is a photoelectric conversion element (silicon photodiode), 4 is a partition plate, 5 is an adhesive, 7 is a substrate, 8 is a light reflection plate, 9 is a detector case, 10 is an X-ray detection element array, and 11 is A collimator, 12 is a connector, 13 is a holding plate, 14 is packing, 15 is a subject, and 16 is an X-ray tube. In addition, 200 shows the multi-element X-ray detector of this invention.

As shown in FIG. 1, the X-ray beam 1 radiated from the X-ray tube 16 in a fan shape passes through the subject 15 and then enters the X-ray detector 200. X-ray detector 200
The inside of the X is composed of X-ray detection elements of multiple channels.
The line detection element array 10 is linearly arranged on the same plane.

In FIG. 2, each X-ray detecting element array 10
Then, the incident X-rays are converted by the scintillator 2 into light having an intensity corresponding to the intensity, and the light is further incident on the photoelectric conversion element (silicon photodiode) 3 to be converted into an electric current. An electric signal corresponding to the line strength is obtained.

One element (X-ray detection element) of the multi-element X-ray detector 200 is a scintillator 2 processed into a predetermined size.
And the photoelectric conversion element 3 which is attached by a transparent adhesive 5 so that the scintillator 2 and the light receiving surface are in contact with each other.

Here, the scintillator material is grooved later to separate the channels, and when the X-ray detecting element array 10 is arranged, the element pitches of the end channels are matched with each other, so that the silicon photodiode 3 has An array that is about 1 mm larger than the array (silicon photodiode array) is used.

The channels are separated from each other by a groove reaching the silicon photodiode 3. The grooves are processed in the focal direction of the X-ray tube 16 (radially in the focal direction of the X-ray tube 16). For simplification of the radial groove processing, the groove processing in one X-ray detecting element array 10 may be performed diagonally all at equal intervals. This is because the distance from the focus of the X-ray tube 16 to the X-ray detection element array 10 is X.
This is because it is considered that the X-rays incident on the adjacent channels may be considered to be parallel, because the pitch is much longer than the pitch of each channel of the line detection element array 10.

Regarding the end channels of the X-ray detecting element array 10, when the X-ray detecting element array 10 is arranged linearly, two adjacent X-ray detecting element arrays 10,
The two X-ray detection element arrays 10 and 10 are arranged so that the element pitches of the ten adjacent end channels are substantially equal to each other.
The end channels are machined at an average slant angle of each slanted groove.

A partition plate 4 is inserted into both end surfaces of the scintillator 2 having such a separated structure, that is, the grooves. This partition plate 4 is a scintillator 2 which is generated by the X-rays incident on the scintillator 2 when the light emitted from the scintillator 2 of each X-ray detection element leaks into an adjacent channel.
Prevent scattered X-rays from leaking into the adjacent channel,
This is for effectively utilizing the light emission in the scintillator 2 as the output of that channel. As the partition plate 4, a tungsten or molybdenum plate, which is a material having a high X-ray absorption coefficient, is polished, and aluminum is vapor-deposited on the surface to increase the light reflectance.

As described above, the X-ray detecting element array 10 is linearly arranged on the same plane, and each X-ray detecting element is arranged in the X direction.
Multi-element X-ray detector 20 oriented in the focal direction of the tube 16.
0 is configured, and when used in a plane scan type X-ray imaging apparatus, downsizing and cost reduction can be achieved.
The difference in the X-ray detection characteristics between the line detection elements (channels), especially the difference in the X-ray detection characteristics between the channel near the center of the detector and the channel near the end of the detector can be largely eliminated.

FIG. 3 is an enlarged cross-sectional view of the essential parts of another embodiment of the present invention. In this embodiment, a light shielding layer 6 made of an opaque resin is provided in place of the partition plates 4 provided on both end faces of the scintillator 2 in the above-described embodiment. Here, the light shielding layer 6 is also provided on the surface of the scintillator 2 having a structure separated by groove processing.

This light-shielding layer 6 is provided inside the scintillator 2
However, since the surface of the scintillator 2 directly hits the incident X-rays, the scintillator 2 whose surface is less likely to be deteriorated by X-ray irradiation is used.

As the material of the light shielding layer 6, it is suitable to add a dye to a resin such as epoxy. The light-shielding layer 6 is made of an opaque material for that purpose, and has a high light-reflectance in order to efficiently use the light emission inside the scintillator 2. Further, the additive dye is made of a white-based material uniformly on a resin. By mixing, the characteristic variation of each X-ray detecting element can be suppressed.

[0032]

As described above, according to the present invention, X
Since the line detection element array is linearly arranged on the same plane, the line detection element array is suitable for a plane scan type X-ray imaging apparatus, and is easier to manufacture than a conventional arc-shaped multi-element X-ray detector. Also, the processing accuracy and the assembly accuracy can be sufficiently obtained, and there is an effect that downsizing and cost reduction can be achieved. Also, each X
Since the X-ray detection elements (channels) are oriented in the focal direction of the X-ray tube, the difference in X-ray detection characteristics between the X-ray detection elements, especially when used in a plane scan X-ray imaging apparatus,
There is also an effect that the difference in X-ray detection characteristics between the channel near the center of the detector and the channel near the detector end can be largely eliminated.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a multi-element X-ray detector according to the present invention.

FIG. 2 is an enlarged view of a part of FIG.

FIG. 3 is an enlarged sectional view of a main part of another embodiment of the present invention.

FIG. 4 is a perspective view of a conventional multi-element X-ray detector.

5 is a sectional view taken along line VV of FIG.

FIG. 6 is an enlarged view of a part of FIG.

[Explanation of symbols]

 1 X-ray beam 2 Scintillator 3 Photoelectric conversion element (silicon photodiode) 4 Partition plate 5 Adhesive 6 Light shielding layer 7 Substrate 8 Light reflection plate 9 Detector case 10 X-ray detection element array 11 Collimator 12 Connector 13 Presser plate 14 Packing 15 Subject 16 X-ray tube

Claims (1)

[Claims] 1. A scintillator that emits visible light having an intensity corresponding to the intensity of X-rays from an incident X-ray tube and a photoelectric conversion element that converts visible light incident on a light-receiving surface into an electric signal. In a multi-element X-ray detector configured by arranging a plurality of X-ray detection element arrays, the X-ray detection element arrays are linearly arranged on the same plane, and each X-ray detection element is of the X-ray tube. A multi-element X-ray detector oriented in the focal direction.