WO2009125632A1

WO2009125632A1 - Portable solid-state radiation detector

Info

Publication number: WO2009125632A1
Application number: PCT/JP2009/053875
Authority: WO
Inventors: 誠角
Original assignee: コニカミノルタエムジー株式会社
Priority date: 2008-04-10
Filing date: 2009-03-02
Publication date: 2009-10-15
Also published as: JP2011128172A

Abstract

Provided is a portable solid-state radiation detector, i.e. a thin portable FPD compatible with a cassette for CR, wherein a scintillator is not destroyed even if a pressure is applied externally in a normal use and occurrence of glare due to scattering of radiation can be prevented. A portable solid-state radiation detector (1) having a housing (3) which houses a sensor panel (21) equipped with a plurality of photoelectric conversion means (152) formed on a substrate (213) and a scintillator (211) provided on the photoelectric conversion means (152) opposite thereto and converting incident radiation into light, and a base (24) provided with a circuit (23) related to the photoelectric conversion means (152) on the surface opposite to a surface facing the sensor panel (21), is further provided with a cushioning member (25) between the sensor panel (21) and the base (24).

Description

Portable radiation solid state detector

The present invention relates to a portable radiation solid state detector.

Conventionally, for the purpose of disease diagnosis and the like, a radiographic image taken using radiation, which is typified by an X-ray image, has been widely used. Such medical radiographic images were conventionally taken using a screen film, but in recent years, digitization of radiographic images has been realized. For example, a stimulable phosphor layer forms radiation transmitted through a subject. After being stored in the photostimulable phosphor sheet, the photostimulable phosphor sheet is scanned with laser light, and thereby the photostimulated light emitted from the photostimulable phosphor sheet is photoelectrically converted to image data. A CR (Computed Radiography) apparatus that obtains the above has been widely used (see, for example, Patent Documents 1 and 2).

In radiographic imaging, a cassette (see, for example, Patent Documents 1 and 2) in which a recording medium such as a screen film or a photostimulable phosphor sheet is housed is used. The CR cassette used for photographing with the CR apparatus can continue to use existing equipment such as a cassette holder or a bucky table that has been introduced to be compatible with conventional screen / film cassettes. In this way, the screen / film cassette is designed and manufactured following the JIS standard size. In other words, the cassette size compatibility is maintained, and the facility is effectively utilized and the image data is digitized.

Recently, as a means for obtaining a medical radiation image, a flat panel detector (hereinafter referred to as “FPD”) is known as a detector that detects irradiated radiation and acquires it as digital image data. (See, for example, Patent Document 3).

Furthermore, portable imaging devices (portable radiation solid detectors) in which this FPD is housed in a housing (housing) have come into practical use (see, for example, Patent Documents 4 and 5). Such a portable radiation solid-state detector can be carried so that it can be taken in a patient's room or the like, and can be photographed. Since it is possible to adjust the angle and angle, it is expected to be widely used.

By the way, as described above, the currently popular CR cassette is sized according to the JIS standard size of the conventional screen / film cassette, and the Bucky table and the like are also made according to the JIS standard size. ing. For this reason, if the portable radiation solid-state detector, which is a portable FPD, can be used in a cassette housed in this JIS standard size, the existing equipment installed in the facility is used. It can be used for photographing, and capital investment when introducing FPD as photographing means can be minimized.

However, the portable radiation solid state detector housed in the conventional housing (housing) described in Patent Document 4 and Patent Document 5 does not conform to the JIS standard size, and uses existing equipment. It is a shape that can not be.

On the other hand, when the portable radiation solid-state detector is formed according to the above JIS standard size, it becomes a thin flat plate as a whole, so even if a load is applied, the internal glass substrate, electrical components, etc. are not loaded. Thus, it is necessary to improve the overall strength so that the deformation of the housing can be suppressed.

In particular, when a patient's weight (load) is applied to the portable radiation solid-state detector, the radiation incident surface of the housing is likely to be bent. In many portable radiation solid state detectors, a scintillator that converts incident radiation into light is often formed as a columnar crystal by vapor deposition of a phosphor in which a luminescent center substance is activated in a base material such as CsI. Such scintillators are generally more easily broken by external force than photoelectric conversion means such as photodiodes or glass substrates.

For this reason, in the portable radiation solid-state detectors described in Patent Document 6 and Patent Document 7, it is proposed to provide a buffer member between the radiation incident surface of the housing and the photoelectric conversion means.
JP 2005-121783 A JP 2005-114944 A JP-A-9-73144 JP 2002-311527 A US Pat. No. 7,189,972 Japanese Patent No. 3815792 Japanese Patent No. 40112182

However, in the methods described in Patent Document 6 and Patent Document 7, the distance between the scintillator and a subject such as a patient's body placed on the radiation incident surface of the housing of the portable radiation solid detector is increased. Radiation is scattered by the subject, glare occurs, and image degradation of the detected radiation image occurs.

Further, Patent Document 6 proposes that a plurality of containers, in which a gas such as air is enclosed, are arranged side by side as a buffer member between the radiation incident surface of the housing of the portable radiation solid-state detector and the photoelectric conversion means. However, it cannot be said that a plurality of containers may scatter incident radiation, and the radiation image is not adversely affected.

Further, when the portable radiation solid detector is formed according to the JIS standard size as described above, it is practically difficult to have a structure in which a large buffer member is inserted between the radiation incident surface of the housing and the photoelectric conversion means. It is.

Accordingly, the present invention has been made to solve the above-described problems, and is a portable FPD that is thin and compatible with a cassette for CR, and is externally used in a normal use state. It is an object of the present invention to provide a portable radiation solid state detector that can prevent the scintillator from being destroyed even if pressure is applied to it, and can prevent the occurrence of glare due to radiation scattering.

In order to achieve the above object, the present invention provides:
A sensor panel comprising a plurality of photoelectric conversion means formed on a substrate, and a scintillator provided opposite to the photoelectric conversion means for converting incident radiation into light;
A base provided with a circuit related to the photoelectric conversion means on the surface opposite to the surface facing the sensor panel;
In the housing,
Further, the portable radiation solid-state detector is characterized in that a buffer member is provided between the sensor panel and the base.

According to the portable radiation solid-state detector of the system of the present invention, the thickness of the housing in the radiation incident direction is, for example, 16 mm or less, so that an existing table such as a bucky table provided for a cassette for CR can be used. Equipment and equipment can be used. In addition, since the buffer member is provided between the sensor panel and the base, even if pressure is applied from the outside in a normal use state, the buffer member disperses the pressure applied to the scintillator and effectively absorbs it. It is possible to effectively reduce the pressure sensitivity, and it is possible to effectively prevent the scintillator from being destroyed.

Also, since such an advantageous effect is obtained by providing the buffer member between the sensor panel and the base, it is not necessary to provide the buffer member between the radiation incident surface of the housing and the sensor panel. Therefore, the distance between the scintillator and the subject such as the patient's body placed on the radiation incident surface is not increased, and it is possible to prevent the occurrence of glare due to the radiation being scattered by the subject. Furthermore, since the buffer member is provided downstream of the scintillator and the photoelectric conversion element in the radiation incident direction, even if the radiation is scattered by the buffer member, it only scatters the radiation after passing through the scintillator and the photoelectric conversion element. Therefore, there is no adverse effect on the radiographic image, and image degradation of the detected radiographic image can be avoided.

It is a perspective view which shows the portable radiation solid detector concerning this embodiment. It is a disassembled perspective view of the housing in this embodiment. It is a disassembled perspective view of the modification of a housing. It is a figure which shows the buffer member of the 2nd cover member in which cross-sectional shape was formed in V shape. It is a figure which shows the state which the detector unit was guided and moved to the horizontal position. It is a figure which shows the state with which the detector unit was hold | maintained by the buffer member. It is the schematic which shows the internal structure of the portable radiation solid detector shown in FIG. FIG. 6 is a cross-sectional view taken along line AA in FIG. 5. FIG. 6 is a sectional view taken along line BB in FIG. 5. It is a graph which shows the load concerning a scintillator for every imaging posture. It is a figure which shows the example of the apparatus for applying a load to a portable radiation solid state detector. It is a figure which shows schematic structure of a pressure measuring device. It is a graph which shows an example of the stress in the scintillator measured with a pressure measuring device. It is a graph which shows the relationship between the maximum value of the stress concerning a scintillator, and each load. It is a top view which shows the sensor panel in this embodiment. It is the side view which looked at the sensor panel shown in FIG. 13 from arrow F direction. It is GG sectional drawing of the sensor panel shown in FIG. It is an enlarged view which shows the structure of a scintillator layer. It is an equivalent circuit block diagram for 1 pixel of the photoelectric conversion part which comprises a signal detection part. FIG. 18 is an equivalent circuit configuration diagram in which the photoelectric conversion units illustrated in FIG. 17 are two-dimensionally arranged. It is a graph which shows the relationship between the thickness of a buffer member, and the pressure sensitivity in a scintillator layer.

Hereinafter, an embodiment of a portable radiation solid state detector according to the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

FIG. 1 is a perspective view of a portable radiation solid state detector in the present embodiment. The portable radiation solid detector 1 in this embodiment is a cassette-type FPD, and the portable radiation solid detector 1 detects the irradiated radiation and acquires it as digital image data (FIG. 5 and the like). And a housing 3 in which the detector unit 2 is accommodated.

In this embodiment, the housing 3 is formed so that the thickness in the radiation incident direction is 16 mm or less so as to meet the JIS standard size in the above-described CR cassette and the conventional screen / film cassette. Yes.

FIG. 2 is an exploded perspective view of the housing 3 in the present embodiment. As shown in FIG. 2, the housing 3 covers the housing main body 31 formed in a hollow rectangular tube

shape having openings

311 and 312 at both ends, and the

openings

311 and 312 of the housing main body 31. A first lid member 32 and a second lid member 33 are provided.

In the present embodiment, the case of the housing 3 in which the housing main body 31 is formed in a rectangular tube shape as described above will be described. However, the configuration of the housing 3 is not limited to this, and for example, as shown in FIG. In addition, the housing 3 can be formed in a substantially box shape with a front member 3A, a back member 3B, a lid member 3C, etc. arranged on the radiation incident side of the portable radiation solid-state detector. The present invention also applies.

In the present embodiment, as shown in FIG. 2, the first lid member 32 and the second lid member 33 include

lid body portions

321 and 331 and

insertion portions

322 and 332, for example, non-conductive. It is made of a non-conductive material such as plastic.

The lid

main body portions

321 and 331 are formed so that the outer circumference thereof is substantially equal to the outer circumference of each of the

openings

311 and 312 of the housing main body portion 31. Moreover, the dimension in the insertion direction with respect to the opening

parts

311 and 312 of the cover main-

body parts

321 and 331 is 8 mm in this embodiment. In addition, although it does not specifically limit how much the said dimension of the lid | cover main-

body parts

321 and 331 is made, It is preferable that the said dimension shall be 6 mm or more about the lid | cover main-body part 321 provided with the antenna device 9 mentioned later. 8 mm or more is more preferable.

The

insertion portions

322 and 332 have a frame shape having an opening on the insertion side with respect to the

openings

311 and 312, and the outer periphery of the

insertion portions

322 and 332 is formed by the

openings

311 and 312 of the housing main body 31. It is formed to have a dimension slightly smaller than the dimension of the inner periphery.

Buffer members 323 and 333 (see FIG. 5 and the like) that can relieve external force transmitted from the outside to the detector unit 2 are provided inside the

insertion portions

322 and 332. The

buffer members

323 and 333 are not particularly limited as long as the external force can be reduced. For example, foamed urethane, silicon, or the like can be applied.

Further, in particular, as shown in FIG. 4A, the buffer member 333 provided in the insertion portion 332 is arranged so that the end of the detector unit 2 is guided to the horizontal position along the inclination of the end of the buffer member 333. The cross-sectional shape is substantially V-shaped. Further, if the buffer member 333 is formed of a deformable material such as an elastic body, a viscous body, a viscoelastic body (viscoelastic), the second lid member 33 as shown in FIGS. 4B and 4C. Is pushed into the housing body 31, the shape of the buffer member 333 is deformed in accordance with the shape of the end of the detector unit 2, and the end of the detector unit 2 is held by the buffer member 333. Thus, the buffer member 333 also functions as a holding member that holds the detector unit 2 at an appropriate position inside the housing 3.

As shown in FIG. 2, from each side of the

insertion portions

322 and 332,

engagement pieces

324 and 334 as engagement means for engaging the housing main body portion 31 and the

lid members

32 and 33 are opened portions 311. It extends in the insertion direction with respect to 312. Engagement

convex portions

325 and 335 are provided on the outer surfaces of the

engagement pieces

324 and 334, respectively.

In addition, it is preferable that a waterproof ring (not shown) formed of rubber or the like is provided on the outer peripheral surface of the

insertion portions

322 and 332. When a waterproof ring is provided, the adhesion between the housing main body 31 and the

lid members

32 and 33 is increased, and moisture and foreign matter such as dust, patient sweat, and disinfectant enter into the housing 3. Can be prevented.

On one side of the lid main body 321 of the first lid member 32 and perpendicular to the radiation incident surface X of the portable radiation solid detector 1 (see FIG. 1), the portable radiation solid detector 1 and An antenna device 9 for transmitting and receiving information wirelessly with an external device is embedded.

The antenna device 9 includes a pair of

flat radiation plates

91 and 92 made of metal, and a power feeding unit 93 that connects the pair of

radiation plates

91 and 92 and supplies power to the pair of

radiation plates

91 and 92. Is provided. In the present embodiment, of the pair of

radiation plates

91 and 92, one radiation plate 91 is formed so that the shape in front view is a trapezoid, and the other radiation plate 92 has a substantially circular shape in front view. It is formed to become. The power feeding unit 93 is connected to the approximate center of the upper bottom portion of one radiation plate 91 and is connected to a part of the other radiation plate 92. A predetermined gap is formed between the pair of

radiation plates

91 and 92 by being connected by the power supply unit 93.

Note that the type and shape of the antenna device 9 are not limited to those illustrated here. The antenna device 9 is not limited to the case where it is embedded in the lid main body portion 321, and may be attached to the outside or the inside of the lid main body portion 321. However, since the antenna device 9 is provided at a position close to a conductive member made of a conductive material such as metal or carbon, the reception sensitivity and the reception gain are lowered. Therefore, the housing formed of a conductive material such as carbon is used. It is preferable to be provided as far as possible from the main body 31 and various electronic components 22 formed of metal or the like (see FIG. 5 etc.), preferably at least 6 mm or more, more preferably 8 mm or more. .

In this respect, in this embodiment, as described above, the antenna device 9 is provided in the lid main body portion 321 formed of a non-conductive material, and the dimension of the lid main body portion 321 in the insertion direction with respect to the opening 311 is as follows. 8 mm. For this reason, the antenna device 9 is disposed at a position 8 mm away from the housing main body 31 formed by including a conductive material such as carbon fiber, which is preferable for maintaining reception sensitivity and reception gain.

Further, on one surface of the lid main body 321 and the same surface on which the antenna device 9 is formed, as shown in FIGS. 1 and 2, the rechargeable battery 26 ( A charging terminal 45 that is connected to an external power source or the like when charging (see FIG. 5 etc.) is formed, and a power switch 46 for switching on / off the power source of the portable radiation solid state detector 1 is disposed. Has been. Furthermore, an indicator 47 formed of, for example, an LED or the like, which displays the charging status of the rechargeable battery 26 and various operating statuses, is formed at the corner formed by the surface on which the antenna device 9 is formed and the radiation incident surface X. Is provided.

In the present embodiment, the case where the antenna device 9 and the charging terminal 45 are all provided in the first lid member 32 is illustrated, but all or part of them is the second lid member 33. It is good also as a structure provided in etc. Further, the interface parts such as the antenna device 9 and the charging terminal 45 are not limited to those exemplified here, and other parts may be included, or a part of them may not be provided. Also good.

For example, the housing main body 31 is formed by winding a carbon fiber on a core material (mold) to obtain a desired thickness (for example, 1 mm to 2 mm), adjusting the shape, and thermosetting the wound carbon fiber. It is formed by pouring the resin, molding it by baking at high temperature and pressure, and then removing the core material.

When the housing main body 31 is formed by such a method, the dimension of the inner periphery of the housing main body 31 is accurately determined by the dimension of the outer periphery of the core material (mold). 31 can be formed easily. Further, since the housing main body 31 can be formed as a seamless integrated structure, the external force / external pressure can be dispersed when an impact or the like is applied from the outside. The housing body 31 may be formed, for example, by winding a plate-like carbon fiber (not shown) around a core material (mold) and baking it at high temperature and pressure.

As shown in FIG. 2 and FIG. 5, the housing body 31 is located at a position corresponding to the engagement

convex portions

325 and 335 of the

engagement pieces

324 and 334 of the

lid members

32 and 33 as shown in FIGS. Engagement recesses 315 and 316 that engage with the

projections

325 and 335 are formed.

In the housing 3, the insertion portion 322 of the first lid member 32 is inserted into the opening 311 at one end portion of the housing body 31, and the insertion portion of the second lid member 33 is inserted into the opening portion 312 at the other end portion. By inserting 332 and engaging the engaging

convex portions

325 and 335 with the engaging

concave portions

315 and 316, respectively, both the opening

portions

311 and 312 are closed, and the inside is sealed and integrated. ing. The means for joining the housing body 31 and the

lid members

32 and 33 is not limited to those exemplified here, and may be joined by, for example, screwing or may be bonded and fixed.

In the present embodiment, the first lid member 32 and the second lid member 33 are fixed to the housing body 31 and cannot be removed after once assembled. By comprising in this way, the airtightness inside the housing 3 can be improved. For this reason, for example, when it is necessary to replace the rechargeable battery 26, the

lid members

32 and 33 are destroyed and the portable radiation solid detector 1 is disassembled. The

lid members

32 and 33 are relatively inexpensive and have little loss even if they are destroyed. On the other hand, the internal detector unit 2 can be taken out in a reusable manner.

5 is a plan view of the state in which the detector unit 2 is housed in the housing 3 as viewed from the lower side (the side opposite to the radiation incident side during imaging), and FIG. 6 is a cross-sectional view taken along the line AA in FIG. 7 and 7 are sectional views taken along line BB in FIG. In FIG. 5, for convenience of explanation, the internal state of the housing 3 is shown without the bottom surface of the housing body 31.

As shown in FIGS. 5 to 7, the detector unit 2 includes a sensor panel 21, a circuit board 23 on which various electronic components 22 are mounted, and a circuit related to a photodiode 152 as a photoelectric conversion element to be described later is provided. It is configured with. In the present embodiment, the circuit board 23 is fixed to a surface of the base 24 made of resin or the like on the side opposite to the surface facing the sensor panel 21.

Further, a buffer member 25 is provided between the sensor panel 21 and the base 24. For the buffer member 25, a known material having flexibility such as foamed polypropylene, polyurethane, non-woven fabric, rubber, or elastomer is used. Further, as the thickness of the buffer member 25 increases as described later, the stress applied to the scintillator layer (light-emitting layer) 211 as the scintillator described later in the sensor panel 21 and the later can be reduced. It is appropriately determined in consideration of the thickness in the incident direction.

Furthermore, in this embodiment, although not shown in FIGS. 6 and 7, a thin lead plate is provided between the buffer member 25 and the base 24 so that the electronic components 22 and the like of the circuit board 23 are not irradiated with radiation. (Thickness is, for example, about 0.1 mm). Further, a buffer member may be provided between the circuit board 23, the electronic component 22, the base 24, and the like and the bottom surface of the housing main body 31.

Here, the scintillator layer 211 (CsI scintillator), which will be described later, of the detector unit 2 housed in the housing 3 is not affected by an external load (such as a patient's weight). As described later, the load needs to be equal to or lower than the allowable limit stress of the CsI scintillator having columnar crystals.

The patient (subject) takes various postures on the radiation incident surface X of the housing 3 of the portable radiation solid-state detector 1 at the time of actual patient imaging, and acts on the CsI scintillator (scintillator layer 211). As shown in FIG. 8, the external load [kg] to be changed changes according to the imaging posture of the patient (for example, 90 kg).

In the measurement of the external load acting on the CsI scintillator and the following experiment, as the portable radiation solid detector 1, the housing main body 31 uses a pitch-based carbon fiber having a tensile elastic modulus of 790 Gpa as the carbon fiber, and the housing The portable radiation solid-state detector 1 having a structure in which the side surface portion 3 has a height of 16 mm and the housing main body 31 has a thickness of 2 mm was used. Further, as the size, a half-cut size (size of 14 inches × 17 inches) which is most likely to bend was used. Further, the portable radiation solid state detector 1 was placed on a relatively high rigidity such as a Bucky table and measured.

Further, an experiment conducted on an external load acting on a CsI scintillator having a columnar crystal of the portable radiation solid detector 1 assumed at the time of actual patient imaging will be described with showing data. Also in this experiment, the conditions such as the configuration and size of the housing main body 31 are the same as described above. Moreover, the load with respect to the portable radiation solid detector 1 presses the center part of the radiation incident surface X of the portable radiation solid detector 1 mounted in the Bucky table etc. with the apparatus shown in FIG. 9, for example of diameter 80mm. The mass of the weight W placed on the upper part of the cylindrical body M was changed variously, and the load applied to the radiation input surface X was changed.

Further, the force (stress) acting on the CsI scintillator (scintillator layer 211) is measured using the pressure measuring device 7. For example, as shown in FIG. 10, the pressure measuring device 7 converts a change in pressure applied from the outside into an electric signal by a pressure-sensitive element and outputs the electric signal, and the electric signal output from the sensor sheet 71 is a sensor. And a computer 73 that receives the data via the connector 72. Specifically, the measurement was performed using an I-SCAN system manufactured by Nitta Corporation.

In this experiment, the stress P [kg / cm ² ] in the CsI scintillator measured by the pressure measuring device 7 has different values in each part of the CsI scintillator, for example, as shown in FIG. Therefore, FIG. 12 shows the experimental results showing the relationship between the maximum value Pmax of the stress P applied to the CsI scintillator measured when the load [kg / φ80] due to the weight W is variously changed and each load of the weight W. Show.

In FIG. 12, the experimental results in the portable radiation solid detector 1 of the present embodiment in which the foamed polypropylene buffer member 25 (thickness 1 mm) is provided between the sensor panel 21 and the base 24 as described above. (A in FIG. 12) and the experimental results (B in FIG. 12) in a portable radiation solid detector not provided with a buffer member, which were performed as a control experiment, are described.

As shown in FIG. 12, the case where the buffer member 25 is provided between the sensor panel 21 and the base 24 and the case where the buffer member 25 is not provided are significant in the external load acting on the CsI scintillator (scintillator layer 211). There is a difference. As described above, when the buffer member 25 is provided between the sensor panel 21 and the base 24 as in the present embodiment, an external load acting on the CsI scintillator (scintillator layer 211) can be applied compared to the case where the buffer member is not provided. It becomes possible to reduce.

On the other hand, as shown in FIG. 5, in this embodiment, the circuit board 23 on which the electronic component 22 is mounted is divided into four parts, which are arranged near the corners of the sensor panel 21 and the base 24. ing. The electronic component 22 is arranged on the circuit board 23 along the outer periphery of the sensor panel 21. The electronic component 22 is preferably arranged at a position as close to each corner of the sensor panel 21 as possible.

By arranging the electronic component 22 on the circuit board 23 in this way, when the detector unit 2 is housed in the housing 3, the electronic component 22 is subjected to external forces in the vicinity of the corner portion of the housing 3 and the peripheral portion of the housing main body portion 31. Are arranged along a region that is difficult to deform (high strength). In addition, the number, arrangement | positioning, etc. of the circuit board 23 and the electronic component 22 are not limited to what was illustrated here.

In the present embodiment, as the electronic component 22 disposed on the circuit board 23, for example, a CPU (central processing unit) or a ROM (read only memory) that constitutes a control unit 27 (see FIG. 18) that controls each unit. , A storage unit (not shown) including a RAM (Random Access Memory), a scanning drive circuit 16 (see FIG. 18), a signal readout circuit 17 (see FIG. 18), and the like. In addition to the ROM and RAM, an image storage unit that includes a rewritable read-only memory such as a flash memory or the like and that stores an image signal output from the sensor panel 21 may be provided.

The detector unit 2 is provided with a communication unit (not shown) that transmits and receives various signals to and from an external device. For example, the communication unit transfers the image signal output from the sensor panel 21 to the external device via the antenna device 9 described above, and receives the imaging start signal transmitted from the external device via the antenna device 9. It is like that.

In addition, on the base 24, when the detector unit 2 is housed in the housing 3, the portable radiation is disposed at a position near the charging terminal 45 provided in the first lid member 32. A plurality of driving units constituting the solid state detector 1 (for example, a scanning driving circuit 16 (see FIG. 18) described later, a signal reading circuit 17 (see FIG. 18), a communication unit, a storage unit, a charge amount detecting unit (not shown), an indicator 47, sensor panel 21 etc.), a rechargeable battery 26 is provided as a power supply unit for supplying power.

As the rechargeable battery 26, for example, a rechargeable battery such as a nickel cadmium battery, a nickel metal hydride battery, a lithium ion battery, a small sealed lead battery, or a lead storage battery can be used. Further, a fuel cell or the like may be applied instead of the rechargeable battery 26. Note that the shape, size, number, arrangement, and the like of the rechargeable battery 26 as the power supply unit are not limited to those illustrated in FIG.

The rechargeable battery 26 is electrically connected to the above-described charging terminal 45 by being installed at a predetermined position on the base 24. For example, the portable radiation solid state detector 1 is connected to an external power source. By attaching to a charging device (not shown) such as a cradle to be connected, the terminal on the charging device side and the charging terminal 45 on the housing 3 side are connected to charge the rechargeable battery 26.

A flexible harness 327 made of a flexible material is provided at the end of the circuit board 23 connected to the various electronic components 22 and the rechargeable battery 26. The circuit board 23 and the like are electrically connected to the charging terminal 45, the power switch 46, the indicator 47, and the antenna device 9 provided on the first lid member 32 by the flexible harness 327. Note that a method of connecting the flexible harness 327 to the charging terminal 45 of the first lid member 32 may be a connector or may be soldered.

13 is a plan view of the sensor panel 21, FIG. 14 is a side view of the sensor panel 21 as viewed from the direction of arrow F in FIG. 13, and FIG. It is sectional drawing.

The sensor panel 21 includes a first glass substrate 214 having a scintillator layer (light emitting layer) 211 formed on one surface as a scintillator that converts incident radiation into light, and is laminated below the scintillator layer 211. A signal detector 151 (see FIG. 18) that detects the converted light and converts it into an electric signal is configured to include a second glass substrate 213 formed on one surface, and these are laminated. It has a laminated structure.

The scintillator layer 211 has, for example, a phosphor as a main component and outputs an electromagnetic wave having a wavelength of 300 nm to 800 nm, that is, an electromagnetic wave (light) ranging from ultraviolet light to infrared light centering on visible light, based on incident radiation. It is like that.

The phosphor used in the scintillator layer 211 is, for example, a material using CaWO ₄ or the like as a base material, or a luminescent center substance in a base material such as CsI: Tl, Cd ₂ O ₂ S: Tb, or ZnS: Ag. An activated material can be used. Further, when the rare earth element is M, a phosphor represented by a general formula of (Gd, M, Eu) ₂ O ₃ can be used. In particular, CsI: Tl and Cd ₂ O ₂ S: Tb are preferable because of high radiation absorption and light emission efficiency. By using these, high-quality images with low noise can be obtained.

As shown in the enlarged view of FIG. 16, the scintillator layer 211 is formed on a support 211b formed of various polymer materials (polymers) such as a cellulose acetate film, a polyester film, and a polyethylene terephthalate film. The phosphor 211a is formed in a layer shape by a growth method, and the layer of the phosphor 211a is composed of columnar crystals of the phosphor 211a. As the vapor phase growth method, a vapor deposition method, a sputtering method, a chemical vapor deposition (CVD) method or the like is preferably used. In any method, the layer of the phosphor 211a can be vapor-phase grown into an independent elongated columnar crystal on the support 211b.

The scintillator layer 211 is affixed to the lower side of the first glass substrate 214 (the side opposite to the side on which radiation is incident during imaging), and the upper side of the first glass substrate 214 (the side on which radiation is incident during imaging). A glass protective film 215 is further laminated. A second glass substrate 213 is laminated below the scintillator layer 211 (the side opposite to the side on which radiation is incident during imaging), and a glass protective film is disposed below the second glass substrate 213. 216 is further laminated.

Both the first glass substrate 214 and the second glass substrate 213 have a thickness of about 0.6 mm. Note that the thickness of the first glass substrate 214 and the second glass substrate 213 is not limited to 0.6 mm. Further, the first glass substrate 214 and the second glass substrate 213 may have different thicknesses.

In addition, the first glass substrate 214 and the second glass substrate 213 (see FIG. 14 and the like) are cut at the end surfaces with a laser so that the end surfaces, that is, the cut surfaces, and the cut surfaces and the upper surfaces of the glass substrates are separated. The ridge line portion and the ridge line portion between the cut surface and the lower surface of the glass substrate are smoothed.

Here, the smoothing process by cutting the end surfaces of the first glass substrate 214 and the second glass substrate 213 with a laser will be described.

When cutting glass, first, streaks (scratches) are formed on the glass surface to form vertical cracks in the thickness direction of the glass (scribing work), and stress is applied to break up the cracks. It is common to go through two work processes called (work). Conventionally, the work of scuffing the glass surface (scribing work) has been performed using cemented carbide, electrodeposited diamond, sintered diamond, or the like. However, when the glass surface is scratched with cemented carbide or diamond, fine irregularities are formed on the cut (divided) glass end face, and this irregularity part is applied when a load such as bending is applied to the glass. Since stress concentrates on the surface, there is a problem that it is easy to break.

In this respect, in this embodiment, an operation (scribing operation) for scratching the surfaces of the first glass substrate 214 and the second glass substrate 213 using a laser is performed. When the laser is used in this way, the end face of the glass after cutting (dividing) is smoothed, so that the strength of the glass against a load such as bending can be increased.

Rather than the magnitude of the external force, the glass substrate cracks are caused by the formation of partial burrs and partial convexities that cause stress concentration when the glass substrate is cut. Thus, by performing the process of smoothing the end face after cutting, it is possible to prevent the occurrence of cracking of the glass substrate even for a considerable external force (stress).

As a cutting device for cutting the end surfaces of the first glass substrate 214 and the second glass substrate 213 with a laser, for example, in a laser oscillation unit, YAG (Yttrium Aluminum Garnet yttrium / aluminum / garnet crystal) is used as a laser optical medium. A YAG laser or the like to be used is preferably used, but the cutting device used for cutting is not limited to this.

The electromagnetic wave (light) output from the scintillator layer 211 is converted into electric energy and accumulated on the upper side of the second glass substrate 213 (the side facing the scintillator layer 211 described above), and is based on the accumulated electric energy. A signal detector 151 (see FIG. 18), which is a detector that outputs an image signal, is formed.

As described above, in the present embodiment, the signal detection unit 151 is stacked on the lower side of the scintillator layer 211, the second glass substrate 213 disposed on the lower side of the signal detection unit 151, and the scintillator layer 211. The signal detection unit 151 and the scintillator layer 211 are sandwiched between the first glass substrate 214 disposed on the upper side of the first glass substrate 214.

Conventionally, it was thought that cracking of the glass substrate could not be prevented unless the stress acting on the internal glass substrate through the housing was suppressed. Therefore, as described above, a space was provided between the housing and the glass substrate. A large number of cushioning members that relieve / reduce the external force were used in the space. For this reason, the housing is further increased in size.

In this regard, the present inventors have found that the cracks in the glass substrate are not the magnitude of the external force acting on the glass substrate, but rather the partial burrs that cause stress concentration when cutting the glass substrate, It has been found that this is due to the formation of convex and concave portions. Therefore, in order to remove the burrs and the convex and concave portions that cause the stress concentration, a process of smoothing the end face after cutting is performed, and thereby the patient acting on the housing 3 having the above-described configuration is processed. It has become possible to prevent the occurrence of cracks and the like of the

glass substrates

213 and 214 with respect to loads and deflections caused by weight and the like.

Further, a sealing member 217 is provided along the outer peripheral edge of the first glass substrate 214 and the second glass substrate 213, and the first glass substrate 214 and the second glass substrate are provided by the sealing member 217. 213 is bonded and bonded. Thereby, intensity | strength can be raised more with respect to loads, such as a bending.

Further, when the first glass substrate 214 and the second glass substrate 213 are bonded together, the first glass substrate 214 and the second glass substrate 213 are deaerated by, for example, sucking air from the space between the first glass substrate 214 and the second glass substrate 213. Adhesion and bonding by the sealing member 217 are performed later, thereby preventing moisture contained in the air from affecting the scintillator layer 211 and the like, and extending the life of the scintillator layer 211 and the like. Can be planned.

Further, a buffer member 218 for protecting the sensor panel 21 from an external impact or the like is provided in each corner of the sensor panel 21 and in the vicinity of the middle between the corners.

Here, the circuit configuration of the sensor panel 21 will be described. FIG. 17 is an equivalent circuit diagram of a photoelectric conversion unit for one pixel constituting the signal detection unit 151.

As shown in FIG. 17, the configuration of the photoelectric conversion unit for one pixel includes a photodiode 152 as a photoelectric conversion element, and a thin film transistor (hereinafter referred to as “TFT”) that extracts electric energy accumulated in the photodiode 152 as an electric signal by switching. 153). The photodiode 152 is an image sensor that generates and accumulates charges. The electrical signal taken out from the photodiode 152 is amplified by an amplifier 154 to a level that can be detected by the signal readout circuit 17.

Specifically, when light is irradiated, a charge is generated in the photodiode 152, and when a signal reading voltage is applied to the gate G of the TFT 153, the charge is transferred from the photodiode 152 connected to the source S of the TFT 153. It flows to the drain D side of the TFT 153 and is stored in a capacitor 154 a connected in parallel to the amplifier 154. The amplifier 154 outputs an electric signal amplified in proportion to the electric charge accumulated in the capacitor 154a.

When the amplified electrical signal is output from the amplifier 154 and the electrical signal is extracted, the switch 154b connected in parallel to the amplifier 154 and the capacitor 154a is turned on, and the charge accumulated in the capacitor 154a is released. The amplifier 154 is reset. The photodiode 152 may simply be a photodiode having a regulation capacitance, or may include an additional capacitor in parallel so as to improve the dynamic range of the photodiode 152 and the photoelectric conversion unit.

FIG. 18 is an equivalent circuit diagram in which such photoelectric conversion units are two-dimensionally arranged, and between the pixels, the scanning lines Ll and the signal lines Lr are arranged so as to be orthogonal to each other. One end side of the photodiode 152 is connected to the source S of the TFT 153, and the drain D of the TFT 153 is connected to the signal line Lr. On the other hand, the other end side of the photodiode 152 is connected to the other end side of the adjacent photodiode 152 arranged in each row, and is connected to a bias power source 155 through a common bias line Lb.

The bias power source 155 is connected to the control unit 27 so that a voltage is applied to the photodiode 152 through the bias line Lb according to an instruction from the control unit 27. The gates G of the TFTs 153 arranged in each row are connected to a common scanning line Ll, and the scanning line Ll is connected to the control unit 27 via the scanning drive circuit 16. Similarly, the drain D of the TFT 153 arranged in each column is connected to a signal readout circuit 17 connected to a common signal line Lr and controlled by the control unit 27.

The signal readout circuit 17 is provided with the amplifier 154 for each signal line Lr described above. At the time of signal reading, a signal reading voltage is applied to the selected scanning line Ll, whereby a voltage is applied to the gate G of each TFT 153 connected to the scanning line Ll, and each photodiode is connected via each TFT 153. The charge generated in the photodiode 152 flows from the signal line 152 to each signal line Lr. Then, each amplifier 154 amplifies the charge for each photodiode 152, and information of the photodiode 152 for one row is extracted. This operation is performed for all the scanning lines Ll by switching the scanning lines Ll, whereby information is extracted from all the photodiodes 152.

A sample hold circuit 156 is connected to each amplifier 154. Each sample and hold circuit 156 is connected to an analog multiplexer 157 provided in the signal readout circuit 17, and the signal read out by the signal readout circuit 17 is described above from the analog multiplexer 157 via the A / D converter 158. It is output to the control unit 27.

Note that the TFT 153 may be either an inorganic semiconductor type used in a liquid crystal display or the like, or an organic semiconductor type. Further, in the present embodiment, the case where the photodiode 152 as a photoelectric conversion element is used as the imaging element is illustrated, but a solid-state imaging element other than the photodiode may be used as the photoelectric conversion element.

On the side of the signal detector 151, a scanning drive circuit 16 that sends a pulse to each photodiode (photoelectric conversion element) 152 to scan and drive each photodiode 152, and the electric power stored in each photoelectric conversion element A signal readout circuit 17 for reading out energy is arranged.

Next, the operation of the portable radiation solid detector 1 in this embodiment will be described.

As described above, in the present embodiment, the first lid member 32 and the second lid member 33 (see FIG. 2) of the portable radiation solid-state detector 1 are open at one end of the housing body 31. The insertion portion 322 of the first lid member 32 is inserted into 311, the insertion portion 332 of the second lid member 33 is inserted into the opening 312 at the other end, and the engagement recess 315 of the housing body 31 is inserted. Engaging

projections

325 and 335 are engaged with 316, respectively.

After that, the first lid member 32 and the second lid member 33 are firmly fixed to the housing body 31 so that they cannot be removed from the housing body 31. Therefore, the entire housing 3 including the housing main body 31, the first lid member 32, and the second lid member 33 is integrated.

The housing 3 is formed as described above, and the thickness T of the buffer member 25 is set so that the sensor panel 21, the buffer member 25, the base 24, and the like are overlapped as shown in FIG. FIG. 19 shows an experimental result of examining how the pressure sensitivity (unit: [dB]) in the scintillator layer 211 of the sensor panel 21 changes when various pressures are applied and the same pressure is applied.

In addition, it experimented about the case where a foamed polypropylene is used as the buffer member 25. FIG. In FIG. 19, the thickness T of the buffer member 25 is 0 mm. The buffer member 25 is not provided, and the second glass substrate 213 and the base 24 of the sensor panel 21 are connected via the lead thin plate described above. This represents the case of direct fixing.

As shown in FIG. 19, it can be seen that the pressure sensitivity in the scintillator layer 211 decreases as the thickness T increases to 0.5 mm and 1 mm, compared to the case where the thickness T of the buffer member 25 is 0 mm. Specifically, according to this experiment, when the thickness T of the buffer member 25 is 0 mm, the pressure sensitivity is about 2 dB when the thickness T is 0.5 mm, and the thickness T is 1 mm. The pressure sensitivity is reduced by about 6 dB. In other words, it is shown that the load reduction effect is greater when the buffer member 25 is disposed at a position closer to the scintillator layer 211.

The decrease in pressure sensitivity when the thickness T of the buffer member 25 is increased is not limited to the case where the buffer member 25 is formed of foamed polypropylene, but is the same when formed of a material such as polyurethane, nonwoven fabric, rubber, or elastomer. Met. On the other hand, although illustration is omitted, the buffer member is the inner surface (back plate Y) of the back plate Y of the housing body 31 (the back plate opposite to the radiation incident surface X of the housing body 31 (see FIG. 6)). 19 is provided between the sensor panel 21 and the base 24 as in the present embodiment, as shown in the right side of the graph of FIG. Compared to the case, the significant difference is small.

Then, as in the case where the weight (load) of the patient is applied to the portable radiation solid detector 1, pressure is applied to the radiation incident surface X (see FIG. 1) of the housing 3 of the portable radiation solid detector 1 as a whole. In this case, the stress is also applied to the scintillator layer 211. However, by providing the buffer member 25 between the sensor panel 21 and the base 24 as in the present embodiment, the pressure applied to the scintillator layer 211 is dispersed. Since it is absorbed, its pressure sensitivity becomes small.

Therefore, even when the scintillator layer 211 is formed as a columnar crystal by vapor deposition of a phosphor in which a luminescent center substance is activated in a base material such as CsI, it is difficult to be destroyed by external force. When the buffer member 25 is actually formed using foamed polypropylene, nonwoven fabric or the like having a thickness of about 0.5 mm and used in the normal use state of the portable radiation solid detector 1, the columnar shape of the phosphor of the scintillator layer 211 is obtained. The crystals were not damaged.

As described above, according to the portable radiation solid-state detector 1 according to the present embodiment, the thickness of the housing 3 in the radiation incident direction is 16 mm or less, and the range of the JIS standard size in the conventional screen / film cassette. Because it is a size that fits inside, even when photographing with the portable radiation solid state detector 1 that is a cassette type FPD, use existing devices and equipment such as a bucky table provided for the cassette for CR. Can do.

In addition, since the buffer member 25 is provided between the sensor panel 21 and the base 24, the buffer member 25 disperses the pressure applied to the scintillator (scintillator layer 211) even if pressure is applied from the outside in a normal use state. In order to absorb effectively, the pressure sensitivity in the scintillator can be effectively reduced, and even when the phosphor of the scintillator is formed of columnar crystals, the columnar crystals are effectively prevented from being damaged or destroyed. It becomes possible.

Furthermore, since the above advantageous effect is obtained by providing the buffer member 25 between the sensor panel 21 and the base 24, the radiation incident surface X of the housing 3 of the portable radiation solid detector 1 and the sensor are obtained. There is no need to provide a buffer member between the panel 21. Therefore, for example, when a buffer member is provided between the radiation incident surface X of the housing 3 and the sensor panel 21, the distance between the scintillator and the subject such as the patient's body placed on the radiation incident surface X becomes longer. The radiation is scattered by the subject and the glare is generated to cause the image degradation of the detected radiation image. However, it is possible to prevent the occurrence of such a glare.

Further, in the case where a buffer member is provided between the radiation incident surface X of the housing 3 and the sensor panel 21, there is a possibility that the radiation incident by the buffer member will be scattered. There is no need to provide a buffer member, and the buffer member 25 of the present invention is provided downstream of the scintillator or photoelectric conversion element in the radiation incident direction. Therefore, even if radiation is scattered by the buffer member 25, the scintillator or photoelectric conversion Since it only scatters the radiation after passing through the element, there is no adverse effect on the radiation image.

In the above embodiment, the case where the scintillator layer 211 that is a scintillator is formed on one surface of the first glass substrate 214 has been described. However, the method of forming the scintillator is not limited to this, and the present invention is also a scintillator. It is not limited to the formation method.

For example, as in the above-described embodiment, the scintillator is formed in layers by forming phosphor columnar crystals on a support such as a cellulose acetate film, for example, by vapor deposition such as vapor deposition. For example, a polyethylene terephthalate film (PET), a polyester film, a polymethacrylate film, a nitrocellulose film having a thickness of about 0.6 mm, similar to the first glass substrate 214 described above, It can also be formed by sticking to the surface of a resin film such as a cellulose acetate film, a polypropylene film, or a polyethylene naphthalate film.

Similarly, a scintillator formed in a layered form by forming phosphor columnar crystals on a support is disposed so as to cover the photoelectric conversion element (photodiode 152) formed on the surface of the second glass substrate 213. It is also possible to arrange the scintillator on the photoelectric conversion element so as to cover with a sealing material from above.

In this case, for example, a heat-sealable resin is used as the sealing material, and the sealing material is fused by a generally used impulse sealer. Examples of the heat-fusible resin include, but are not limited to, ethylene vinyl acetate copolymer (EVA), polypropylene (PP) film, and polyethylene (PE) film.

Of course, the present invention is not limited to the above-described embodiment and its modifications, but can be modified as appropriate.

In the medical field, it may be used as a radiation individual detector for obtaining radiographic images for diagnosis.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Portable radiation solid state detector 3 Housing 21 Sensor panel 23 Circuit board (circuit)
24 Base 25 Buffer member 152 Photodiode (photoelectric conversion element)
211 Scintillator layer (scintillator)
211a Phosphor 213 Second glass substrate (substrate)
214 First glass substrate (separate substrate)

Claims

A sensor panel comprising a plurality of photoelectric conversion means formed on a substrate, and a scintillator provided opposite to the photoelectric conversion means for converting incident radiation into light;
A base provided with a circuit related to the photoelectric conversion means on the surface opposite to the surface facing the sensor panel;
In the housing,
The portable radiation solid-state detector further comprises a buffer member provided between the sensor panel and the base.
The portable radiation solid state detector according to claim 1, wherein the housing has a thickness in a radiation incident direction of 16 mm or less.
The portable radiation solid state detector according to claim 1 or 2, wherein the scintillator is made of a columnar crystal of a phosphor by vapor deposition.
The scintillator is formed by vapor deposition on one surface of a substrate separate from the substrate,
The substrate and the separate substrate are integrated so that the surface of the substrate on which the plurality of photoelectric conversion means are provided and the surface of the separate substrate on which the scintillator is deposited are opposed to each other. The portable radiation solid-state detector according to any one of claims 1 to 3, wherein the portable radiation solid-state detector is provided.
5. The portable radiation solid state detector according to claim 4, wherein the substrate separate from the substrate is a glass substrate.