JPS6291880A - Radiation array sensor - Google Patents

Abstract

PURPOSE:To obtain an image having a high reliability, and to improve the S/N by arraying regularly each photoelectric transducing element along a linear groove. CONSTITUTION:A radiation array sensor 1 is constituted of a scintillator base material 2 formed by providing plural linear grooves 21, and a photoelectric transducing element 3 which has been inserted and provided in each of these linear grooves 21, and an exposed surface of the base material 2 is covered with a TiO2 film 4. Also, as for the element 3, transparent electrode films 33, 34 are formed on both faces of a semiconductor layer 32 of a pn structure, and also X-ray and a visible light shielding plate 35 is laminated. In this state, in the sensor 1, radiant ray which is irradiated from the upper face passes through the film 4 and made incident on the inside of the base material, and converted to visible light therein. However, since the photodetecting surface of the element 3 in set in the vicinity of the side of a visible light converting area, the light is made incident on the photodetecting surface efficiently and detected as an output of the respective elements 3. Also, since the element 3 is set to the linear grooves 21 which have been provided regularly at an equal interval, a distortion, etc. of an image are not generated, and the S/N can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a radiation array sensor. More specifically, the present invention relates to a radiation array sensor used as an element of a linear type sensor or two-dimensional sensor for transmitting radiation for measuring an image with a radiation measuring device when radiation is irradiated onto an object.

(B) Conventional technology Conventionally, an object is irradiated with radiation such as X-rays, and the transmitted radiation and its distribution are measured using a number of radiation measuring instruments to obtain an image.
Based on this, a method of obtaining information inside an object has been carried out, and it has come to be widely used in X-ray CT and the like.

In order to obtain images of such transmitted radiation, conventionally, as shown in FIG.
A first diode (3) is glued to the scintillator base material (on the bottom of 2), and radiation such as X-rays incident from the top surface of the scintillator is converted into visible light within the scintillator, which is then converted into an electrical signal. Radiation 04I to convert the intensity! Sensor (
100) are used, and usually a plurality of linear or two-dimensional array sensors (101) are arranged in advance in the image measurement area as shown in FIG.
It is used to measure h1 the intensity distribution of X-rays transmitted from the A source (5) through the object (6).

(c) Problems to be Solved by the Invention However, in the conventional radiation sensor (100), a plurality of 1111. When combining them to form a linear or two-dimensional array sensor (101), it is difficult to arrange and fix the sensors (100) at equal intervals, and this error reduces the reliability of the obtained image. There was a problem. Furthermore, since the photodiode (3) is glued to the bottom surface of the scintillator, there is a problem in that the reception efficiency of visible light converted within the scintillator is insufficient, making it difficult to obtain a clear image with excellent resolution.

This invention was made in view of such problems,
In particular, radiation arrays with excellent reliability and resolution are intended to provide the following benefits.

(d) Means for Solving the Problems Thus, according to the present invention, there is provided a scintillator base material having a comb-shaped cross section in which a plurality of linear grooves are regularly provided, and a light-receiving surface within each linear groove of the scintillator base material. and a photoelectric conversion element inserted along the inner surface of the linear groove.

The most distinctive feature of this invention is that the array sensor is constructed by incorporating a plurality of photoelectric conversion elements into one scintillator base material, instead of being constructed by combining individual radiation sensors as in the past, and that the array sensor is constructed by incorporating a plurality of photoelectric conversion elements into one scintillator base material. The conversion element is inserted and assembled into a plurality of regularly provided linear grooves in the scintillator base material so that the light-receiving surface runs along the inner surface.

The linear grooves of the scintillator base material are installed at intervals depending on the resolution, and can be easily produced by cutting the surface of the scintillator using a dicing machine, for example. The groove width and groove depth are determined according to the shapes of the photoelectric conversion elements provided, and preferable examples thereof will be shown in the examples described below.

On the other hand, a photodiode element is suitable as the photoelectric conversion element to be installed, and in order to prevent cross-talking and obtain appropriate resolution, it has a light-receiving surface on one side and a layer blocking radiation and visible light on the other side. It is preferable to use a material with a blocking layer .delta., such as one in which a radiation or visible light blocking layer is set and two photodiodes stacked on both sides of the blocking layer.

Examples of such photodiode elements include those made of ordinary silicon wafers and those made of amorphous silicon. In particular, when a photodiode element made of amorphous silicon is used, the element thickness can be reduced and a sensor with even better resolution can be obtained. Note that these photodiode elements may be integrally combined with an electric signal amplification circuit at the end thereof, as shown in FIG. In the figure, (to) is the photoelectric conversion area, (g) is the amplification and switching circuit area, (1)
indicate the 3i parking boards, respectively.

Although various known solid scintillators can be used as the scintillator base material, it is preferable to use CdWOa crystal. In addition, a visible light reflective film such as TlO2 is applied to the exposed surface of the scintillator base material of the array sensor to prevent visible light from entering from the outside and to prevent visible light converted inside from leaking to the outside. It is preferable to cover it with

(E) Function In the radiation array sensor of the present invention, a plurality of photoelectric conversion elements are set corresponding to the linear grooves of the scintillator base material that are regularly provided in advance, and each of the comb-shaped convex portions and the photoelectric conversion The element functions as one radiation sensor.

The radiation incident on each comb-shaped convex portion from the top surface is converted into visible light and is quickly detected by a photoelectric conversion element having a light-receiving surface located on the side.

(F) Embodiment FIGS. 1 to 3 are configuration explanatory diagrams showing an embodiment of the radiation array sensor of the present invention. In the figure, the late fJ4I!
The il array sensor (1) is made of Cd WO4 crystal (1 mm
X 26mm X 4mm > Width 0 at 0.8mm intervals
．． The scintillator is composed of a scintillator base material (2) having a comb-shaped cross section and a photodiode element (3) inserted into each of the linear grooves 31. On the exposed surface of the base material (2),
It is coated with a white T+02 film (4).

The photodiode element (3) has a transparent electrode film made of ITO formed on both sides of a semiconductor layer with a PN structure, and an aluminum plate (copper plate, tungsten plate, etc. can also be used) on one side. It is made by laminating X-ray and visible light blocking plates (G), and a blocking plate (M) is placed on the inner wall surface of each linear #42+).
It is inserted so that the front surface and the light-receiving surface are aligned and fixed with an optical adhesive (on the light-receiving surface side) and an adhesive such as Araldite (on the shielding plate side). Note that 01) is the output lead wire of the FJ + - diode element (3), which is connected to the electric No. 3 amplifier circuit and the display section.

In such a radiation array sensor (1), the l11m ray irradiated from the top surface is transmitted through the visible light reflective Ti02 film (4
) and enters the scintillator base material, where it is converted into visible light. However, since the light receiving surface of the photodiode element is set close to the side of the visible light conversion area, the light receiving surface is efficiently converted into visible light. The light enters and is detected as the output of each photodiode element. and a blocking plate (g)
This also prevents crosstalk between adjacent photodiodes. In addition, since the photodiode elements are set in linear grooves that are regularly provided at equal intervals, there is no distortion during assembly (image distortion, etc.) that occurs in conventional array sensors. It has excellent resolution and a large S/N ratio (can provide clear images with lower radiation energy than conventional methods).

In addition, in the above example, white Ti02111 (
4), it prevents stray light from entering from the outside and also prevents visible light converted inside from leaking to the outside, further improving resolution and sensitivity (for example,
(approximately twice as much).

The depth of the linear groove in the above example is CdWO.

It is most suitable when used as the scintillator base material. That is, the relationship between the scintillator CdWOa and its transmitted radiation dose is as shown in FIG.
The transmission of commonly used X-rays at approximately 311 Im is suppressed. Therefore, it is most preferable to set the depth of the linear groove to about 3 mm in terms of scintillation efficiency of incident radiation and miniaturization and weight reduction of the array sensor.

Furthermore, although the photodiode element in the above embodiment has a PN structure made of a silicon wafer and has a thickness of 0.6 mm, a photodiode using a PIN structure semiconductor layer using an amorphous silicon semiconductor The thickness of the element can be significantly reduced (for example to a thickness of 2ffIII).

FIG. 4 is a diagram corresponding to FIG. 3 showing another embodiment of the radiation array sensor of the present invention. The late FF4-line array sensor shown in FIG. 4 consists of the photodiode element (3) of the above embodiment.
As a result, the PIN structure semiconductor (32A) (32[3) and the transparent electrode film (3
3A) (33B) <34A) (34B>) The structure is similar except that a composite photodiode element in which two photodiodes consisting of VIWI are used is used.

Note that (31Δ)(31B> is the output lead wire of each photodiode. In the radiation array sensor of this embodiment, the visible light is converted within each scintillator section between adjacent linear grooves and is distributed to the left and right. Since light directly enters the light-receiving surfaces of the two photodiodes arranged oppositely through these, the detection sensitivity can be further improved. Such semiconductors (32A) (32B)
Therefore, it is preferable to use an amorphous silicon semiconductor because a layered structure can be easily formed without increasing the width of the linear groove.

(G) Effects of the Invention The radiation array sensor 12 of the present invention has highly reliable i! i-image can be obtained.

Furthermore, since the photoelectric conversion element is provided on the side of each scintillator fraction rather than on the bottom of the scintillator,
The scintillation light reception efficiency has also been improved, and S/
The N ratio has also been improved.

[Brief explanation of drawings]

FIG. 1 shows an example of the radiation array sensor of the present invention/II
FIG. 2 is a plan view, FIG. 3 is a partial sectional view, FIG. 4 is a view equivalent to FIG. 3 showing another example, and FIG. 5 is a scintillator thickness and transmitted radiation dose. 6 is a diagram showing the structure of a conventional radiation sensor, FIG. 7 is a diagram showing the structure of a conventional radiation array sensor in use, and FIGS. FIG. 7 is a plan view and a cross-sectional view showing another example of a photoelectric conversion element used in a radiation array sensor. (1)...... Radiation 04-ray array sensor, ('2J・
...Scintillator base material, (3)...Photodiode element, (/I)...Ti02 film, 31)...Linear groove. Fig. 4 Fig. 5 Scintillator (CdW (2) width (mm) Fig. 6 Fig. 3 ゛ Fig. 8 Fig. 7

Claims (1)

[Scope of Claims] 1. A scintillator base material having a comb-shaped cross section in which a plurality of linear grooves are regularly provided, and a light-receiving surface within each linear groove of the scintillator base material along the inner surface of the linear groove. A radiation array sensor comprising a photoelectric conversion element inserted as shown in FIG. 2. The sensor according to claim 1, wherein the scintillator base material is coated with a TiO_2 film. 3. The sensor according to claim 1, wherein the photoelectric conversion element is a photodiode having a light-receiving surface on one side and a radiation and visible light blocking layer on the other side. 4. The sensor according to claim 1, wherein the photoelectric conversion element comprises two amorphous photodiodes on both sides of a radiation and visible light blocking layer.