JP2003004854A - Radiation detector and radiation detection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent stray light from being incident on a photoelectric conversion element 1. SOLUTION: In a radiation detector, a part of a reading route 301 of an electric signal converted at least by a photoelectric conversion substrate 1 is formed to a light guide plate for guiding light converted by a fluorescent body 3 to the photoelectric conversion substrate 1. Incidence preventing films 303 and 304 preventing the light reflected by the reading route 301 from being incident on the photoelectric conversion substrate 1 are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus, a radiation detection apparatus and an image processing system, and more particularly to an image pickup apparatus such as a medical X-ray image pickup apparatus or an industrial destructible apparatus.
The present invention relates to a radiation detection device and an image processing system.

In this specification, electromagnetic waves such as X-rays, α-rays, β-rays, and γ-rays are included in the category of radiation.

[0003]

2. Description of the Related Art Conventionally, X-rays are converted by a phosphor into visible light proportional to the intensity of the X-rays, converted into electric signals by using photoelectric conversion elements, and converted into digital signals by A / D converters. There is an X-ray digital imaging device that does this.

FIG. 6 is a sectional view of an X-ray digital image pickup apparatus disclosed in Japanese Patent Laid-Open No. 2000-241551. In FIG. 6, 1 is a substrate on which a photoelectric conversion element is formed, 100 is a stud bump formed on a connection terminal provided on the substrate 1, and 2 is an X-ray that is converted into light of a wavelength detectable by the photoelectric conversion element. The scintillator, 3 is an optical fiber plate that guides the light to the photoelectric conversion element without dispersing the light, 4 is a transparent adhesive, and 5 is an FPC (Flexible Print).
ed Circuit: flexible printed circuit board, 6 is a scintillator protective resin, 7 is an anisotropic conductive adhesive, 300 is a connection terminal for connecting to the board 1 via stud bumps,
301 is a connection terminal with the FPC.

[0005]

However, in the conventional technique, a part of the light guided by the optical fiber plate 3 may be reflected by the connection terminal 301 and enter the photoelectric conversion element of the substrate 1 as stray light. there were.

Further, a part of the light guided by the optical fiber plate 3 is diffracted to the back surface side of the substrate 1, and thereafter,
In some cases, the light may return to the front surface side of the substrate 1 and enter the photoelectric conversion element.

Therefore, in particular, the charges converted by the photoelectric conversion element near the connection terminal 301 are superposed with the converted stray light, and the original X-ray information may not be obtained.

Therefore, an object of the present invention is to prevent stray light from entering the photoelectric conversion element.

[0009]

In order to solve the above problems, the present invention relates to a light guide plate for guiding light converted by a phosphor to a photoelectric conversion substrate, and at least an electric light converted by the photoelectric conversion substrate. In the radiation detecting device in which a part of the signal reading path is formed, an incident prevention film is formed so that the light reflected by the reading path does not enter the photoelectric conversion substrate.

Here, the incident prevention film is the antireflection film 303 and the light shielding film 304 in FIG. 1, and the read path is the connection terminal 301 and the electrode wiring 302 in FIG.

The radiation detection system of the present invention is characterized by including a radiation detection device.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a sectional view of an X-ray imaging apparatus according to the first embodiment of the present invention. FIG. 2 is a perspective view from the back surface side of FIG. FIG. 3 is a plan view of the substrate 1 of FIG. FIG. 4 is a plan view showing the optical fiber plate 3 of FIG. Although only one electrode wiring 302 is shown in FIG. 4 for simplification, the connection terminal 300 and the connection terminal 301 are actually connected by an electrode wiring not shown.

1 to 3, 1 is a substrate on which a photoelectric conversion element is formed (photoelectric conversion substrate), 100 is a stud bump formed on a connection terminal provided on the substrate 1, and 2 is X.
A scintillator for converting a line into light of a wavelength detectable by a photoelectric conversion element (for example, visible light), 3 is an optical fiber plate for guiding the light to the photoelectric conversion element without dispersing the light, 4 is a transparent adhesive, 5 is FPC (Flexible Printed C
ircuit: flexible printed circuit board), 6 is a scintillator protective resin, 7 is an anisotropic conductive adhesive, 300 is a connection terminal for connecting the substrate 1 to the substrate 1 via the stud bump 100, and 301 is an anisotropic conductive adhesive. FPC by agent 7
5 is a connection terminal, and 303 is a connection terminal 300, 3
01 is an antireflection film formed on the upper surface, 304 is a light-shielding film formed between the side surface of the substrate 1 and the lower surface of the connection terminal 301, 3
Reference numeral 02 is an electrode wiring for connecting a common signal supplied to the photoelectric conversion element of each substrate 1, power supply, etc., a shaded portion of 102 is an effective imaging area, and 103 is a drive circuit, signal processing circuit, and mounting area of the photoelectric conversion element. .

The antireflection film 303 prevents the reflection of the light guided by the optical fiber plate 3, and the light shielding film 304 guides the light guided by the optical fiber plate 3 and diffracted to the back side of the substrate 1. The photoelectric conversion element No. 1 does not enter.

The antireflection film 303 is the fiber plate 3
A novolac resin containing a photosensitive black pigment is coated thereon by spin coating or the like, and the connection terminal 300 is subjected to steps of pre-baking, exposure, development, and post-baking.
The same as or slightly larger than. Antireflection film 30
3 is desired to be a material which can be formed to be hard and thin because the connection terminal 300 is formed thereon and bump connection is performed.

As shown in FIG. 2, the light-shielding film 304 may be formed at least between the side surface of the substrate 1 and the lower surface of the connection terminal 301, but more reliably prevents stray light from entering the photoelectric conversion element. Therefore, it is preferably formed on the entire surface of the light emitting surface of the optical fiber plate 3 where the substrate 1 is not located. The light-shielding film 304 is coated with a silicone resin, an acrylic resin, an epoxy resin, or the like containing a black pigment by dispense coating or the like, and the resin is cured by heat curing. A material having a high light-shielding effect and an excellent moisture permeability is desired.

In this embodiment, the case where four substrates 1 are arranged is shown, but the number of substrates 1 is not limited to four. The photoelectric conversion element may be formed on the surface of the substrate 1 on the scintillator side (on which the stud bump 100 is mounted) or on the surface opposite to the scintillator side. Further, the electrode wiring 302 may be provided on the substrate 1 side, and the connection terminal of the substrate 1 and the connection terminal 301 of the optical fiber plate 3 may be directly connected.

The optical fiber plate 3 has a diameter of about 5-6.
A plurality of 1 μm optical fibers are bundled, heated and pressed, and then cut into plates. After cutting 50 x 50 mm, thickness 3 m
A plurality of m-sized plates are butted against each other and heat-bonded to form a large optical fiber plate. After that, polishing is performed so that there is no thickness difference between the plates.

Further, on the optical fiber plate 3, a connection terminal 301 for connecting each substrate 1 to an external input / output terminal by face down mounting, a connection terminal 300 for connecting the electrode wiring 302 and the photoelectric conversion element to each other. It is formed by a photo etching process in advance. Electrode terminals and electrode wirings are formed according to the substrate 1 on which a pure aluminum film formed by sputtering or vapor deposition is mounted. Palladium 100 Å, nickel 0.1μ on the aluminum electrode
By stacking m and 0.3 μm of gold by electroless plating, the connection stability is improved.

Further, as shown in FIG. 3, bumps 100 for connection are provided on the connection terminals on the substrate 1. If stud bumps that attach only the ball portion of the ball bonding to the terminal are used, after the ball is attached to the terminal portion with ultrasonic waves and heat, the recrystallized portion of the cut wire remains short and has a convex shape, and it joins with the substrate. Since it is inconvenient for, flatten by crushing the upper surface with another tool. A silver paste is applied to the bumps 100 by a transfer method in order to ensure connection reliability.

An appropriate amount of adhesive is dropped onto the central portion of the portion of the optical fiber plate 3 on which the connection terminal 301, the connection terminal 300 and the electrode wiring 302 are bonded and the bump 100 of the substrate 1 is connected to the connection terminal 300. Positioning is performed so as to be connected to the terminal 301, and temporary crimping is performed.
The adhesive was a so-called underfill agent, and a mixture of a translucent epoxy resin having a large curing shrinkage and a small thermal expansion coefficient and silica was used.

This operation is repeated by the number of boards to be used, and when all the boards to be mounted have been temporarily press-bonded, the main press-bonding is performed.

Further, as shown in FIG. 3, there is no choice but to provide a certain gap between the substrates due to variations in cutting and alignment of the substrates, and here, for example, 50 μm.
They are bonded together with a space of m. The pixel pitch of the substrate 1 is 50 μm, and although one pixel is missing, the missing data can be filled in by complementing the pixel data on both sides.

Further, as shown in FIG. 4, the photoelectric conversion element is manufactured on a silicon wafer and cut by a dicer, but the cutting accuracy is required for the sides where the substrates are adjacent to each other.

The heating conditions for the main compression bonding are the conditions under which the resin component is cured, for example, the temperature conditions are 150 ° C. and 80 sec.
In c, the pressure condition varies depending on the number of terminals, but the load on the device side is appropriately set so as to be 70 to 120 g per terminal.

At the time of the main pressure bonding, a special heater tool capable of performing the main pressure bonding simultaneously for all the substrates by the independent heater bed is used in order to absorb the height variation of the substrate 1 and the height variation of the bumps 100. Alternatively, an integrated heater tool may be provided with a cushioning material that absorbs variations.

Electrode wiring 30 on the optical fiber plate 3
The FPC 5 for supplying power and inputting / outputting signals from the outside is thermo-compressed through 0, and is further sealed with resin to protect the terminal portion and the element portion.

On the surface of the optical fiber plate 3 opposite to the terminal and electrode wiring forming side, a phosphor is laminated on the optical fiber plate or a phosphor film is adhered as a scintillator for converting X-rays into light.

As the material of the phosphor, cesium iodide (CsI) or gadolinium sulfide (Gd ₂ O ₂ S ₂ ) is used, and they are laminated by vacuum vapor deposition. If they are stacked, they may be destroyed by being touched or may be dissolved by humidity, so they are protected by a moisture permeation preventive resin 6 or the like.

Alternatively, a gadolinium sulfide powder mixed with a binder and processed into a film may be used to adhere to the optical fiber plate 3 with an adhesive.

Thus, the X-ray imaging apparatus according to the present invention is constructed.

(Second Embodiment) FIG. 5 is a schematic configuration diagram of an image processing system (X-ray diagnostic system) according to a second embodiment of the present invention. The image sensor 604 shown in FIG.
The imaging device described in the first embodiment is used as 0.

X-ray 60 generated by X-ray tube 6050
Reference numeral 60 passes through the chest 6062 of the patient or subject 6061 and enters the image sensor (imaging device) 6040 according to the present invention having a scintillator mounted on the upper portion. The incident X-ray contains information on the inside of the body of the patient 6061. The scintillator emits light in response to the incidence of X-rays and photoelectrically converts the light to obtain electrical information. This information is converted to digital, image-processed by the image processor 6070, and can be viewed on the display 6080 in the control room.

Further, this information can be transferred to a remote place by a transmission means such as a telephone line 6090, can be displayed on a display 6081 such as a doctor room at another place, or can be stored in a storage means such as an optical disc. It is also possible to diagnose. Also the film processor 6
It is also possible to record by 100 on the film 6110.

[0036]

As described above, according to the present invention,
Since the incident prevention film that prevents the light reflected on the reading path from entering the photoelectric conversion substrate is formed, it is possible to prevent stray light from entering the photoelectric conversion element.

[Brief description of drawings]

FIG. 1 is a sectional view of an X-ray imaging apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view from the back side of FIG.

3 is a plan view of the substrate 1 of FIG. 1. FIG.

4 is a plan view showing the optical fiber plate 3 of FIG. 1. FIG.

FIG. 5 is a schematic configuration diagram of an image processing system (X-ray diagnostic system) according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a conventional X-ray imaging apparatus.

[Explanation of symbols]

1 Substrate provided with photoelectric conversion element 2 Scintillator (phosphor) 3 Optical fiber plate 4 transparent adhesive 5 FPC 6 Scintillator protection resin 7 Anisotropic conductive adhesive 100 stud bump 102 effective imaging area 103 Drive and signal processing IC mounting area and mounting area 300 Photoelectric conversion element connection terminal 301 FPC connection terminal 302 electrode wiring 303 Anti-reflection film 304 Light-shielding film

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kenji Kajiwara             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F term (reference) 2G088 EE01 FF02 FF04 FF05 FF06                       GG15 GG19 JJ05 JJ09                 2H013 AB01 AB10 BA20

Claims (6)

[Claims] 1. A radiation detection apparatus comprising: a light guide plate that guides light converted by a phosphor to a photoelectric conversion substrate, and at least a part of a readout path of an electric signal converted by the photoelectric conversion substrate is formed on the light guide plate. A radiation detecting apparatus, comprising: an incident prevention film that prevents light reflected on the readout path from entering the photoelectric conversion substrate. 2. The radiation detector according to claim 1, wherein the incident prevention film is an antireflection film or a light shielding film, and is formed between the light guide plate and the readout path. apparatus. 3. The incident prevention film is further formed on a light emitting surface of the light guide plate and at a portion where the photoelectric conversion substrate is not located. Radiation detector. 4. The radiation detecting apparatus according to claim 1, wherein the light guide plate has a plurality of optical fibers. 5. The radiation detecting apparatus according to claim 1, wherein the light guide plate includes a shielding material that shields radiation. 6. A radiation detection system comprising the radiation detection device according to claim 1.