JP2003329778A - Radiation detector and radiographic device provided therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray detector capable of arranging a plurality of semiconductor detecting elements without gaps by protecting the semiconductor detecting elements by insulation material, minimizing insensible part and having a good characteristic. <P>SOLUTION: Even closely arranging semiconductor detecting elements 3, films 15 coated on the side of the elements 3 just contact to each other and play a role of cushion so that defects of the elements 3 are prevented. Therefore, a plurality of elements 3 can closely be arranged and the insensible part can be minimized. Although even if semiconductor detecting elements 3 contact to each other, the films 15 are insulating, the characteristics of the elements 3 do not change, and the characteristic can be maintained as good. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects radiation such as X-rays and gamma rays radiated from a radiation source and transmitted through a subject, and an X-ray imaging device, an X-ray CT device, a gamma camera, a positron CT device, and a single device. The present invention relates to a radiation detector used in a photon ECT device or the like, and more particularly to a radiation detector in which a semiconductor is used as a detection element and a plurality of semiconductor detection elements are arranged, and a radiation imaging apparatus including the same.

[0002]

2. Description of the Related Art A radiation detector of a conventional X-ray imaging apparatus is
For example, a combination of an intensifying screen that emits X-rays and fluorescence and an X-ray film, or a combination of an image intensifier that multiplies the scintillation light fluorescent by X-rays and a CCD, The image is converted by converting to and capturing the light (indirect conversion type).

In recent years, amorphous selenium (aS
e) and the like are vapor-deposited to form an X-ray conversion unit, in which X-rays are directly converted into electric charges, and an X-ray imaging device equipped with a radiation detector for reading the electric charges with a TFT switching element is being developed ( Direct conversion type). However, it is technically extremely difficult to produce a sensor large enough to capture an image of the human chest, and it has not yet been put to practical use.

Further, the thickness of the X-ray conversion part in the sensor part is about 0.6 mm in the case of the indirect conversion type, and it is as thin as about 1 mm in the case of the direct conversion type, and the high X-ray energy,
For example, when the X-ray tube voltage is 120 kV, most of it is X
Since the light is transmitted through the line conversion unit, the conversion efficiency is low, and even in the case of the direct conversion type having high conversion efficiency, it is about 60%.

On the other hand, cadmium telluride (CdTe)
2mm because it is possible to obtain a high-density and thick detector element using a semiconductor such as
Thick ones can be obtained. In this case, even if the X-ray tube voltage is 120 kV, almost all X-rays are converted into electric charges, and it is possible to obtain a highly sensitive radiation detector.

However, the ingot diameter of the cadmium telluride crystal obtained in the crystallization manufacturing process is 100 m.
Since it is as small as about m, and there are locally low-quality portions such as crystal defects, a single large element cannot be obtained. Therefore, in order to obtain a radiation detector having a required size, an ingot is sliced into a predetermined thickness and a square (for example, 20 to 25) is avoided while avoiding a crystal defect portion or the like.
It is necessary to arrange a plurality of semiconductor detection elements arranged in mm square).

[0007]

However, the conventional example having such a structure has the following problems. That is, the conventional radiation detector is manufactured by arranging a plurality of semiconductor detection elements, but in order to minimize the dead part where the X-ray detection is impossible between the semiconductor detection elements, the plurality of semiconductor detection elements are arranged. Should be placed as close as possible to each other. However, since the semiconductor detection element is very fragile and easily chipped, there is a problem that it is difficult to dispose the semiconductor detection element in close contact.

Further, because of such a problem, it is the current situation that the semiconductor detecting elements are arranged in a state of being spaced apart from each other, and there is a problem that the number of dead parts increases. Further, when the semiconductor detection elements are forcibly arranged in order to reduce the dead area and the semiconductor detection elements come into contact with each other, the characteristics may change in the contact area as compared with other areas due to electrical conduction.

According to the present invention, by protecting a semiconductor detection element with an insulating material, a plurality of semiconductor detection elements can be arranged without gaps to reduce the dead part as much as possible, but the radiation detector has good characteristics. Another object of the present invention is to provide a radiation imaging apparatus using the same.

[0010]

The present invention has the following constitution in order to achieve such an object.

That is, according to the first aspect of the invention, in a radiation detector formed by arranging a plurality of semiconductor detection elements, an insulating material is applied to each side surface of the plurality of semiconductor detection elements. It is characterized by that.

(Operation / Effect) Even if the semiconductor detection elements are arranged in close contact with each other, the insulating materials adhered to the side surfaces of the semiconductor detection elements only come into contact with each other, which acts as a cushioning material and functions as a cushion. Therefore, it is possible to prevent the semiconductor detection element from being chipped. Therefore, since a plurality of semiconductor detection elements can be closely arranged,
The dead part can be reduced as much as possible. Further, even if the semiconductor detecting elements are in contact with each other, the material is insulative, so that the characteristics of the semiconductor detecting elements do not change, and the characteristics can be maintained as they are.

Further, each of the plurality of semiconductor detection elements is
It is preferably cadmium telluride (CdTe) or cadmium zinc telluride (CdZnTe) depending on the production method and characteristics such as radiation detection sensitivity (claim 2).

Further, the insulating material is preferably a film made of polyethylene terephthalate (PET) (claim 3).

As the insulating material in the present invention, other insulating plastic materials such as polyethylene terephthalate (PET) film, rubber, glass, ceramics, etc. can be used, but PET film is easy to process. This is an advantage.

Further, the PET film is preferable because it has elasticity and can easily absorb impact when the semiconductor detection elements are in contact with each other or when the semiconductor elements are assembled, and damage can be further prevented. In addition, it is more preferable that the thickness is thin in order to reduce the dead area, and polyethylene terephthalate is also suitable from this point.

The insulating material may be applied to the entire side surface of the semiconductor detection element (claim 4), or may be applied to only the four side surfaces excluding the four corners without being applied to the entire surface (claim 4). Item 5).

Even if the insulating material is applied to the entire side surface of the semiconductor detecting element, the same action and effect can be obtained even if the insulating material is applied to the four side surfaces with the four corners exposed except for the four corners. Can play. Alternatively, conversely, the four corners may be covered with an insulating material.

Further, according to the present invention, in a radiation imaging apparatus in which radiation is detected by a radiation detector and imaged by imaging means based on the detected radiation, a plurality of semiconductor detection elements provided in the radiation detector are provided. An insulating material is deposited on each side surface (claim 6).

By adopting the radiation detector in which the side surface of each semiconductor detection element is coated with the insulating material, the characteristics of the radiation detector can be stably maintained and the performance can be maintained for a long period of time. Is possible.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. 1 to 3 relate to an embodiment of the present invention, and FIG. 1 shows an X-ray detector equipped with an X-ray detector according to the embodiment.
FIG. 2 is a block diagram showing a schematic configuration of a radiographic apparatus, FIG. 2 is a vertical sectional view showing a schematic configuration of an X-ray detector, and FIG.
It is a figure which shows the structure of the vertical direction of a line detector.

An X-ray imaging apparatus, which is an example of a radiation imaging apparatus, includes an X-ray detector 1. This X-ray detector 1 is
A plurality of semiconductor detection elements 3 are arranged two-dimensionally, and transmitted X-rays emitted from an X-ray source (not shown) and transmitted through an object such as a subject are detected, and the intensity of each transmitted X-ray is detected. A corresponding charge signal is accumulated for each position. The charge signals thus accumulated for each position are collected by the data collection device 5
Are collected in association with each position. And
It is processed by the image processing device 7 for imaging.

The data based on the transmitted X-rays which have been imaged by the image processing device 7 are displayed on a display device 9 such as a CRT or a liquid crystal display device, or a magneto-optical disk (MO).
It is adapted to be stored in an exchangeable storage medium such as a digital versatile disk (DVD) or an image storage device 11 having a hard disk device.

The image processing device 7 corresponds to the imaging means in this invention, and the X-ray detector 1 corresponds to the radiation detector in this invention.

As shown in FIGS. 1 and 2, the X-ray detector 1
Is a substrate 1 in which a plurality of semiconductor detection elements 3 are densely arranged in a two-dimensional manner.
3 is arranged. A film 15, which is an insulating material, is attached to the entire side surface of each semiconductor detection element 3.

It is preferable that the film 15 has elasticity in order to effectively exert its role as a cushioning material, for example, polyethylene terephthalate (PET).
The thing made is mentioned. Further, the thickness is preferably as thin as possible in order to make the dead area of the X-ray detector 1 as small as possible. For example, the thickness is about 0.02 mm (20 μm).

As shown in FIG. 3, in each semiconductor detection element 3, the electrode 17 has an X of a conversion layer 19 for converting an X-ray into an electric charge.
It is deposited on the entire line incidence surface side. Examples of the material of the conversion layer 19 include cadmium telluride (CdTe) or cadmium zinc telluride (CdZnTe).

Electrodes 21 patterned at predetermined intervals are formed on the surface of the conversion layer 19 opposite to the electrodes 17. The electrode 21 is made of gold (Au), for example. An electrode 23 (for example, made of gold (Au)) is formed on the upper surface of the substrate 13 at a position facing the electrode 21, and the electrode 21 and the electrode 23 are connected by a bump 25. The bump 25 may be made of indium (In), for example. A bias voltage for extracting charges is applied between the electrode 7 and the electrode 21 by the bias power supply 27 (see FIG. 1).

The substrate 13 is provided with a switching circuit such as a TFT switching element, for example, and has a function of reading out the charge signals detected and accumulated by the plurality of semiconductor detection elements 3 depending on the position.

The spatial resolution of the X-ray detector 1 is determined by the interval of the channel pitch ch indicated by the symbol cp in the figure. Specifically, it is about 0.15 mm in the case of the X-ray imaging apparatus in this embodiment, and about 1 mm in the case of the X-ray CT apparatus which is another example of the apparatus.

Next, the film 15 attached to the entire side surface of the semiconductor detection element 3 described above will be described with reference to FIGS.
Will be described in detail with reference to. Note that FIG. 4 is a plan view showing a schematic configuration of the X-ray detector, and FIG. 5 is a schematic view for explaining that a film is attached.

As the film 15, two pairs of thin plates are used, and the pair of films 15a slightly longer than the length of the pair of sides of the semiconductor detection element 3 and the pair of sides of the semiconductor detection element 3 have almost the same length. And a pair of films 15b having As shown in FIG. 5, these films 15 (15a, 15b) are bonded so as to surround the entire side surface of the semiconductor detection element 3 with no space. For these adhesion, for example,
An insulating adhesive is used.

By constructing the X-ray detection apparatus 1 as in this embodiment, the film 15 attached to the side surface of the semiconductor detection element 3 even if the semiconductor detection element 3 is closely arranged.
Only by contacting each other, this serves as a cushioning material and plays a role of a cushion, which can prevent damage to the semiconductor detection element 3.

Therefore, since a plurality of semiconductor detection elements 3 can be arranged in close contact with each other, the dead part can be reduced as much as possible. Further, since the film 15 has an insulating property even when the semiconductor detection elements 3 are in contact with each other, the characteristics of the semiconductor detection element 3 do not change, and the characteristics of the X-ray detector 1 can be maintained as good.

Further, the temperature may change drastically depending on the environment, and the X-ray detector 1 is largely warped due to the difference in temperature coefficient between the semiconductor detection element 3 and the substrate 13, and the X-ray detector 1 is destroyed in the worst case. There is a risk of However, according to the above-described embodiment, the expansion and contraction of the film 1 is prevented even in such a case.
Since 5 absorbs, such a situation can be prevented.

Further, by adopting the X-ray detector 1 in which the film 15 is attached to the side surface of each semiconductor detection element 3, the characteristics of the X-ray detector 1 can be stably maintained. It is possible to maintain the performance of the radiographic apparatus for a long period of time.

The present invention is not limited to the above-mentioned embodiments, but can be modified as follows.

(1) The arrangement of the semiconductor detection elements 3 in the X-ray detector 1 is not limited to the above-mentioned form, and may be arranged as shown in FIGS. 6 and 7, for example. 6 is a side view showing an arrangement example of the semiconductor detection elements, and FIG. 7 is a side view showing another arrangement example.

That is, as shown in FIG. 6, the end portions of the semiconductor detection element 3 may be arranged in different steps so as to minimize the dead portion. Further, as shown in FIG. 7, for the same purpose, they may be arranged so as to be inclined with respect to the incident direction of X-rays. In these X-ray detectors 1, the arrangement of the respective semiconductor detection elements 3 is particularly complicated, so handling is extremely difficult in the manufacturing process, and the semiconductor detection elements 3 are
Is easily damaged. However, since the film 15 is attached to the side surface of each semiconductor detection element 3 as described above, it is possible to prevent the semiconductor detection element 3 from being chipped.

In addition, in the above-mentioned embodiment and the above-mentioned modified example, the dead part can be made smaller than the conventional example, but cannot be completely eliminated. For that part,
The image processing apparatus 7 may perform interpolation processing by software.

(2) The film 15 is preferably deposited on the entire side surface of the semiconductor detection element 3 as described in the embodiments. However, as shown by the dotted line in FIG. 5, the length of the film 15 may be shorter than the sides of the semiconductor detection element 3 so that the film 15 is attached to the four side surfaces except the four corners in plan view. Even with such a film 15 shape, damage to the semiconductor detection element 3 can be prevented more than in the conventional example,
It is much easier to handle.

Further, the film 15 may be formed in a shape sufficiently smaller than one side surface of the semiconductor detection element 3, and a plurality of films 15 may be attached to one side.

Further, the film 15 having a V shape in plan view is formed so as to cover only the side portions of the four corners of the semiconductor detection element 3.
May be attached to the corners. Even with such a configuration, the handling property is improved as compared with the conventional example.

(3) Although the film 15 made of polyethylene terephthalate (PET) is exemplified as the insulating material, other insulating plastic materials, rubber, glass, ceramics and the like can be used in addition to the above.

(4) The film 15 has been illustrated as having a plate-shaped piece adhered thereto. For example, an annular insulating material having a square opening slightly larger than the outer shape of the semiconductor detection element 3 is prepared. The insulating material may be contracted while the semiconductor detection element 3 is placed in this opening to cover the entire side surface of the semiconductor element 3. As the insulating material in this case, heat shrinkable rubber or the like can be used.

(5) Although the X-ray detector 1 has been described as an example of the radiation detector, the present invention can be applied to a radiation detector that detects radiation such as gamma rays.

(6) As the semiconductor detection element 3, the conversion layer 1
Although the example adopting cadmium telluride (CdTe) or cadmium zinc telluride (CdZnTe) is shown in FIG. 9, it is needless to say that the present invention can be applied even if another semiconductor is adopted for the conversion layer 19.

[0048]

As is apparent from the above description, according to the present invention, even if the semiconductor detecting elements are arranged in close contact with each other, the insulating materials adhered to the side surfaces of the semiconductor detecting elements only contact each other. This serves as a cushion and prevents the semiconductor detection element from being chipped. Therefore, since a plurality of semiconductor detection elements can be arranged in close contact with each other, the dead part can be minimized. Further, even if the semiconductor detection elements are in contact with each other, the material is insulative, so that the characteristics of the semiconductor detection elements do not change, and the characteristics can be maintained as they are.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an X-ray imaging apparatus including an X-ray detector according to an embodiment.

FIG. 2 is a vertical sectional view showing a schematic configuration of an X-ray detector.

FIG. 3 is a diagram showing a vertical structure of an X-ray detector.

FIG. 4 is a plan view showing a schematic configuration of an X-ray detector.

FIG. 5 is a schematic view for explaining that a film is attached.

FIG. 6 is a side view showing an arrangement example of semiconductor detection elements.

FIG. 7 is a side view showing another arrangement example of the semiconductor detection element.

[Explanation of symbols]

1 ... X-ray detector (radiation detector) 3 ... Semiconductor detector 7 ... Image processing device (imaging means) 13 ... Substrate 15 ... Film (insulating material) 17 ... Electrode 19 ... Conversion layer 21 ... Electrode 23 ... Electrode 25 ... Bump ch… Channel pitch

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2G088 EE01 FF02 GG21 JJ09 JJ37                 4M118 AA10 AB01 BA05 BA19 CB05                       FB09 FB13 GA10 HA31                 5C024 AX11 AX16 CX38 EX17 GX02                       GZ36                 5F088 AA11 BA13 BA16 BB03 EA14                       JA03 LA08

Claims (6)

[Claims] 1. A radiation detector configured by arranging a plurality of semiconductor detection elements, wherein a side surface of each of the plurality of semiconductor detection elements is coated with an insulating material. 2. The radiation detector according to claim 1, wherein each of the plurality of semiconductor detection elements is cadmium telluride (CdTe) or cadmium zinc telluride (CdZnTe). Detector. 3. The radiation detector according to claim 1 or 2, wherein the insulating material is a film made of polyethylene terephthalate (PET). 4. The radiation detector according to claim 1, wherein the insulating material is applied to the entire side surface of each of the plurality of semiconductor detection elements. . 5. The radiation detector according to claim 1, wherein the insulating material is applied to four side surfaces of each of the plurality of semiconductor detection elements excluding four corners. Radiation detector. 6. A radiation imaging apparatus which detects a radiation by a radiation detector and forms an image by an imaging means based on the detected radiation, on each side surface of a plurality of semiconductor detection elements provided in the radiation detector. A radiation imaging apparatus, characterized by being coated with an insulating material.