JP2012093188A - Radiation detecting panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a contact between adjacent columnar crystals in a configuration in which an interval between the adjacent columnar crystals of a scintillator is changed when a load is applied to a top board of a housing.SOLUTION: After a scintillator 34 including a columnar crystal region is formed on a deposition substrate 20, the deposition substrate 20 is bent (refer to (A)) in such a manner that a scintillator forming surface side of the deposition substrate 20 is protruded, such that an average interval of the adjacent columnar crystals at a periphery of the tip ends of the columnar crystals is formed larger than an average interval of the adjacent columnar crystals at the periphery of the bases of the columnar crystals. When capturing a radiation image, a load is applied to the top board 16 of an electronic cassette 10 and the load is transmitted (refer to (B)) to the scintillator 34 and the deposition substrate 20 via a radiation detecting unit 42 so as to suppress the contact between the adjacent columnar crystals even if the average interval of the columnar crystals is decreased at the periphery of the tip ends of the columnar crystals.

Description

  The present invention relates to a radiation detection panel, and more particularly to a radiation detection panel including a scintillator in which a plurality of columnar crystals are erected on the light emission side, and a light detection unit that detects light emitted from the scintillator.

In recent years, radiation sensitive layers have been arranged on TFT (Thin Film Transistor) active matrix substrates to detect irradiated X-rays, γ-rays, α-rays, and other radiation, and to radiation image data representing the distribution of irradiation dose. An FPD (Flat Panel Detector) that directly converts and outputs has been put into practical use. It incorporates a panel-type radiation detector such as this FPD, an electronic circuit including an image memory, and a power supply unit, and is output from the radiation detector. A portable radiation detection panel (hereinafter also referred to as an electronic cassette) that stores radiation image data in an image memory has been put into practical use. As the radiation sensitive layer, for example, irradiated radiation is once converted into light by a scintillator (phosphor layer) such as CsI: Tl, GOS (Gd ₂ O ₂ S: Tb), and emitted from the scintillator. There is known a configuration (indirect conversion method) in which light is reconverted into an electric charge and stored by a photodetection unit including a PD (Photodiode) or the like. Because the radiation detection panel is excellent in portability, the subject can be photographed while being placed on a stretcher or bed, and the position of the radiation detection panel can be easily adjusted to adjust the imaging part, so it cannot move. It is possible to flexibly cope with shooting of the subject.

  Regarding the radiation detection panel described above, Patent Document 1 discloses a configuration in which a phosphor layer (scintillator) formed at a position corresponding to each pixel of a photodetector is formed of phosphor particles formed in a columnar shape, a trapezoidal shape, or a spindle shape. A radiation detection apparatus is disclosed. In Patent Document 2, a scintillator that converts incident radiation into photons and an optical sensor array that receives the photons and generates an electrical signal corresponding to the photons are arranged on a flexible substrate. A flexible imager is disclosed. Patent Document 3 discloses a radiation detector including a scintillator that absorbs radiation and emits light and a photodetector that detects light emission of the scintillator, and the scintillator has a square frustum shape. A technique is disclosed in which the angle of the hypotenuse is equal to or greater than the inclination angle of the incident radiation and the radiation detection element.

JP 2002-303673 A JP 2004-64087 A JP 2004-125722 A

  When CsI is used as the scintillator of the radiation detection panel and the scintillator has a structure in which a plurality of columnar crystals are erected on the light emission side (see also FIG. 11A), the light generated by the scintillator with radiation irradiation is By proceeding through the columnar crystal, the scattering of light emitted from the scintillator is suppressed, so that it is possible to suppress a reduction in the sharpness of the detected image when the irradiated radiation is detected as an image. Have.

  In the scintillator having the above-described configuration, the CsI filling rate in the columnar crystal formation region in the scintillator has an appropriate range, and depends on the thickness of the columnar crystal formation region, for example, about 70 to 85% is optimal. . That is, when the filling rate of CsI is too small (for example, less than 70%), the light emission amount of the scintillator is significantly reduced. On the other hand, when the filling rate of CsI is too large (for example, higher than 85%), Since the adjacent columnar crystals start to contact each other, a phenomenon in which part of the light traveling in the columnar crystals moves to other columnar crystals in contact (this phenomenon is also called crosstalk) occurs. The pattern of the amount of light emitted from the scintillator changes with respect to the pattern of the radiation irradiation amount, causing a decrease in radiation detection accuracy (decrease in the sharpness of the detected image when the irradiated radiation is detected as an image). Therefore, in order to ensure the sensitivity and accuracy of radiation detection, it is necessary to provide a gap (gap) having an appropriate size between adjacent columnar crystals.

  By the way, the scintillator made of CsI is formed by vapor deposition on a vapor deposition substrate made of Al (aluminum) or the like, and the light detection part is formed on a substrate made of glass or the like, but Al and glass have a large difference in thermal expansion coefficient. (For example, the thermal expansion coefficient of glass is about 30 PPM, whereas the thermal expansion coefficient of glass is about 3 PPM). For this reason, when the scintillator and the light detection unit are bonded over the entire surface for the purpose of improving the detection efficiency of light emitted from the scintillator, the scintillator and the light are caused by the difference in thermal expansion coefficient due to the temperature change. Since the detection portion is warped and a large stress is applied to the columnar crystal of the scintillator (see also FIG. 11B), the columnar crystal may be damaged over time. In order to avoid this, it is conceivable to adopt a configuration in which the scintillator and the light detection unit are brought into contact with each other without being bonded together.

  On the other hand, with regard to the radiation detection panel, for the purpose of improving the handleability and the like, the panel including the scintillator and the light detection unit is accommodated in the casing in a state of being attached to the inner surface of the top plate of the box-shaped casing. Adoption of a configuration that realizes a thin radiation detection panel has been studied. However, in this configuration, for example, when a radiation detection panel is inserted between the base and the body of the subject during radiographic imaging, the weight of the subject's body is applied to the top plate of the housing. The load is applied as a load, and the load is transmitted to the scintillator and the light detection unit, so that the scintillator and the light detection unit are distorted.

  In particular, in order to avoid damage to the columnar crystals of the scintillator, when the scintillator and the light detection unit are brought into contact without bonding, the position of the tip of each columnar crystal moves relative to the light detection unit. As shown in FIG. 11C, as an example, a large stress caused by the difference in thermal expansion coefficient is not applied to the columnar crystal, but distortion is generated in the scintillator and the light detection unit. In this way, the gap between adjacent columnar crystals in the vicinity of the tip of the columnar crystal changes greatly. FIG. 11 schematically shows a columnar crystal. As described above, since the appropriate filling rate of CsI in the columnar crystal formation region in the scintillator is about 70 to 85%, the gap between adjacent columnar crystals is Along with the change, there is a problem in that the tips of adjacent columnar crystals start to come into contact with each other, leading to a decrease in radiation detection accuracy (decrease in the sharpness of the detected image).

  On the other hand, Patent Documents 1 to 3 include a scintillator in which a plurality of columnar crystals are erected on the light emission side, and radiation having a configuration in which the interval between adjacent columnar crystals changes when a load is applied to the top plate of the housing. In the detection panel, when a load is applied to the scintillator, there is no disclosure about the problem that the tip portions of the columnar crystals adjacent to the scintillator may come into contact with each other, and the radiation detection accuracy may be lowered. There is no description of a configuration for solving the problem.

  The present invention has been made in consideration of the above facts, and includes a scintillator in which a plurality of columnar crystals are erected on the light emission side, and the interval between adjacent columnar crystals changes when a load is applied to the top plate of the housing. In the configuration, an object is to obtain a radiation detection panel capable of suppressing contact between adjacent columnar crystals.

  In order to achieve the above object, the radiation detection panel according to the first aspect of the present invention is such that the light emission side on which a plurality of columnar crystals are erected is facing the inner surface of the top plate in a box-shaped housing. The scintillator is disposed in the housing and absorbs the irradiated radiation to emit light from the light emitting side, and is sandwiched between the inner surface of the top plate and the light emitting side of the scintillator. And a light detection unit that detects light emitted from the light exit side of the scintillator and transmits a load applied to the top plate to the scintillator, and the scintillator is formed of the columnar crystal. The average interval between the adjacent columnar crystals in the vicinity of the tip is larger than the average interval between the adjacent columnar crystals in the vicinity of the base of the columnar crystal.

  The radiation detection panel according to the invention of claim 1 is configured to include a scintillator and a light detection unit, and the scintillator has a light emission side on which a plurality of columnar crystals are erected, of a box-shaped housing. It is arranged in the housing in the direction facing the inner surface of the top plate, absorbs the irradiated radiation and emits light from the light emitting side, and the light detection unit is arranged on the inner surface of the top plate of the housing and the light emitting side of the scintillator It is disposed in the housing in a state of being sandwiched between the two and detects light emitted from the light emitting side of the scintillator, and transmits a load applied to the top plate of the housing to the scintillator. The “approximately box-shaped” case according to the present invention includes a case where the top surface corresponding to the top plate and the bottom surface opposite to the top surface are flat and parallel, and the bottom surface is flat and the top surface Includes a case that is curved so as to protrude outwardly from the case. Since the radiation detection panel according to the first aspect of the present invention has the above-described configuration, when a load is applied to the top plate of the housing, the load is transmitted to the scintillator via the light detection unit. The interval between adjacent columnar crystals of the scintillator changes.

  On the other hand, in the first aspect of the invention, the average interval between adjacent columnar crystals near the tip of the columnar crystal is made larger than the average interval between adjacent columnar crystals near the base of the columnar crystal. As a result, even if the distance between the tip ends of the adjacent columnar crystals of the scintillator is reduced by the load applied to the top plate of the housing being transmitted to the scintillator via the light detection unit, the adjacent columnar crystals It becomes difficult for the tips to come into contact with each other. Therefore, according to the first aspect of the present invention, in the configuration including a scintillator in which a plurality of columnar crystals are erected on the light emission side, and a load is applied to the top plate of the housing, the interval between adjacent columnar crystals changes. It can suppress that the adjacent columnar crystal contacts, and it can also suppress that the precision of a radiation detection falls with the contact of an adjacent columnar crystal.

  In the invention described in claim 1, for example, as described in claim 2, the light detection unit is attached to the inner surface of the top plate, and the light detection unit and the light emission side of the scintillator are bonded together. It is possible to adopt a configuration in which the contact is made without being performed.

  Further, in the invention according to claim 1 or claim 2, to make the average interval between adjacent columnar crystals near the tip of the columnar crystal larger than the average interval between adjacent columnar crystals near the base of the columnar crystal, For example, as described in claim 3, it is possible to realize a scintillator having a flat plate shape and one of the upper surface and the bottom surface being a light emitting surface, and deforming the light emitting surface to be convex. The scintillator is deformed as described above, for example, when the scintillator is placed on the first support so that the surface on the opposite side of the light emission surface of the scintillator is in contact with the flat first support. The formed structure can be easily realized by bending the first support, for example, as described in claim 5. Therefore, for example, as described in claim 4, even if the average diameter of the columnar crystals of the scintillator is substantially uniform along the longitudinal direction of the columnar crystals, the average of adjacent columnar crystals in the vicinity of the tip of the columnar crystals It is possible to easily realize the interval larger than the average interval between adjacent columnar crystals in the vicinity of the base portion of the columnar crystal, which facilitates manufacture.

  Also, when the average interval between adjacent columnar crystals near the tip of the columnar crystal is larger than the average interval between adjacent columnar crystals near the base of the columnar crystal, the filling rate of the scintillator near the tip of the columnar crystal is reduced. As a result, the amount of light emission near the tip of the columnar crystal decreases. However, in the invention described in claim 3, when performing radiation detection, the load applied to the scintillator via the light detection unit applied to the top plate of the housing is deformed so that the light exit surface side is convex. It acts on the scintillator as a force for restoring the deformation. For this reason, by reducing the interval between adjacent columnar crystals in the vicinity of the tip of the columnar crystal, when performing radiation detection, the filling rate of the scintillator in the vicinity of the tip of the columnar crystal is increased. There is also an effect that the amount of light emission near the tip of the columnar crystal is increased.

  Further, in the invention described in claim 5, the first support has a characteristic that the shape changes according to the temperature as described in claim 6, for example, and the scintillator is formed on the first support. The temperature may be substantially flat and may be curved in the temperature range when radiation detection is performed by the radiation detection panel. In this case, when the radiation detection panel is manufactured, the step of bending the first support and deforming the scintillator is not necessary, so that the manufacture of the radiation detection panel can be further facilitated.

  Further, in the invention according to any one of claims 1 to 6, for example, as described in claim 7, the flat plate-like second support body on which the light detection portion is formed has flexibility. It is preferable. This eliminates the need to ensure the rigidity of the second support member so that the light detection unit is not damaged when a load applied to the top plate of the housing is transmitted to the light detection unit. Since the thickness can be reduced, the radiation detection panel can be further thinned easily. In addition, in the invention according to claim 7, the light detection unit is configured as described in claim 8, for example, wherein the photoelectric conversion unit constituting the light detection unit is made of a material including an organic photoelectric conversion material. It is preferable to adopt a configuration in which the active layer of the switching element is made of a material containing an organic semiconductor material.

  Further, as described in claim 2, specifically, the contact between the light detection unit and the light emission side of the scintillator without bonding is specifically, for example, as described in claim 9. Each of the scintillator and the light detection unit is fixed to each other so as to prevent relative movement in a direction substantially parallel to the top plate of the housing. Other regions can be realized by abutting without bonding.

  In the invention according to any one of claims 1 to 9, for example, as described in claim 10, radiation is incident on the radiation detection panel from the top plate side of the housing, and the top plate of the housing It is preferable that the radiation incident from the side is transmitted through the light detection unit and irradiated to the scintillator. In this configuration, compared to the case where radiation is irradiated from the opposite side of the top panel side to the radiation detection panel, the portion of the scintillator that is closer to the light detection unit becomes the main light emission region, and the amount of light received by the light detection unit is small. Since it increases, the detection sensitivity of the radiation in a radiation detection panel can be improved.

  Moreover, in the invention according to any one of claims 1 to 3 and claims 5 to 10, the average interval between adjacent columnar crystals in the vicinity of the tip of the columnar crystal is adjacent to the vicinity of the base of the columnar crystal. Increasing the average interval between the columnar crystals means that, as described in claim 11, for example, the scintillator has an average diameter of the columnar crystals near the tip of the columnar crystals and an average diameter of the columnar crystals near the base of the columnar crystals. It can also be realized by making it smaller.

  As described above, in the present invention, since the average interval between adjacent columnar crystals near the tip of the columnar crystal of the scintillator is larger than the average interval between adjacent columnar crystals near the base of the columnar crystal, In a configuration including a scintillator in which a plurality of columnar crystals are erected on the side, there is an excellent effect that adjacent columnar crystals can be prevented from contacting.

It is a perspective view which shows the electronic cassette demonstrated by embodiment partially fractured | ruptured. (A) is a schematic sectional view of the electronic cassette in a state where no load is applied to the top plate, and (B) is a state in which a load is applied to the top plate. It is the schematic which shows typically an example of the crystal structure of a scintillator. It is sectional drawing which showed the structure of the radiation detection part typically. It is a block diagram which shows the principal part structure of the electric system of an electronic cassette. It is a block diagram which shows the principal part structure of the electrical system of a console and a radiation generator. FIG. 2A is a schematic diagram schematically showing a state of a columnar crystal of a scintillator in a steady state, and FIG. In an electronic cassette according to another aspect, (A) is a schematic cross-sectional view showing a state where no load is applied to the top plate, and (B) is a schematic cross-sectional view showing a state where a load is applied to the top plate. It is the schematic which shows typically the other example of the crystal structure of a scintillator. It is sectional drawing which showed typically the structure which provided multiple radiation detection parts. It is the schematic for demonstrating the problem of a prior art.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an electronic cassette 10 as an example of a radiation detection panel according to the present invention. The electronic cassette 10 is made of a material that transmits the radiation X, has an overall box shape, and has a rectangular upper surface (the outer surface of the top plate 16 shown in FIG. 2). A housing 14 is provided as an irradiation surface 12 to be irradiated. Note that portions of the casing 14 other than the top plate 16 are made of, for example, ABS resin, and the top plate 16 is made of, for example, carbon. Thereby, the intensity | strength of the top plate 16 is ensured, suppressing absorption of the radiation X by the top plate 16. FIG. The thickness of the casing 14 is the same size as the thickness of the casing in the conventional cassette configured to record the irradiated radiation as an image on the photosensitive material.

  The irradiation surface 12 of the electronic cassette 10 is composed of a plurality of LEDs, and displays the operation state of the electronic cassette 10 such as the operation mode (for example, “ready state” and “data transmitting”) and the remaining battery capacity. A display unit 12A is provided. The display unit 12A may be composed of a light emitting element other than an LED, or may be composed of display means such as a liquid crystal display or an organic EL display. Further, the display unit 12 </ b> A may be provided at a site other than the irradiation surface 12.

  In the casing 14 of the electronic cassette 10, a radiation detection unit (TFT substrate) 42 as a light detection unit of the present invention is formed from the irradiation surface 12 side along the arrival direction of the radiation X transmitted through the body of the subject. Or the scintillator 34 etc. which are examples of the scintillator of this invention are arrange | positioned in order. Further, inside the housing 14, a case 18 for housing various electronic circuits including a microcomputer and a rechargeable and detachable battery (secondary battery) on one end side along the longitudinal direction of the irradiation surface 12. Is arranged. Various electronic circuits of the electronic cassette 10 including the radiation detection unit 42 are operated by electric power supplied from a battery accommodated in the case 18. In order to avoid damage to various electronic circuits housed in the case 18 due to the radiation X irradiation, a radiation shielding member made of a lead plate or the like is provided on the irradiation surface 12 side of the case 18 in the housing 14. It is arranged.

  As shown in FIG. 2 (A), the scintillator 34 disposed in the housing 14 is formed on the vapor deposition substrate 20 by vapor deposition (details will be described later). The vapor deposition substrate 20 is formed on one surface. After the scintillator 34 is formed by vapor deposition, the scintillator 34 is curved so that the surface on which the scintillator 34 is formed is convex, and the scintillator 34 is also convex on the side opposite to the vapor deposition substrate 20 (light emission surface side). It has been transformed into. Moreover, the top plate 16 of the housing 14 is curved with the same degree of curvature as the scintillator 34 and the vapor deposition substrate 20 so that the irradiation surface 12 side is convex. The vapor deposition substrate 20 is an example of a first support body according to claim 5.

  Furthermore, in this embodiment, the radiation detection part 42 has flexibility because the board | substrate (insulating board | substrate 64 mentioned later) of the radiation detection part 42 is formed with the material which has flexibility. The radiation detector 42 is attached to the inner surface of the top plate 16 over the entire surface by adhesion or the like, and is curved following the top plate 16. Further, the radiation detector 42 and the scintillator 34 are in contact with each other without being bonded, and only the peripheral edge is fixed by the flexible fixing agent 22 over the entire periphery. A base 24 is attached to the bottom surface of the housing 14, and a control board 26 is attached to the lower surface of the top plate of the base 24. The control board 26 and a radiation detection unit (TFT substrate) 42 are attached. Are electrically connected via a flexible cable 28.

  Thus, the scintillator according to the present embodiment is an example of the scintillator according to claims 1 to 5 and claim 9, and the vapor deposition substrate 20 is an example of the first support body according to claim 5, The radiation detection unit 42 is an example of a light detection unit according to claims 1, 2, and 7 to 10.

  In addition, you may comprise the vapor deposition board | substrate 20 with the shape memory alloy which has the characteristic in which a shape changes according to temperature. The shape memory alloy constituting the vapor deposition substrate 20 is substantially flat in the temperature range when the scintillator 34 is formed on the vapor deposition substrate 20 by vapor deposition, and the scintillator in the temperature range when the radiographic image is taken by the electronic cassette 10. If the curved surface is formed so that the formation surface side of 34 is convex, the step of bending the deposition substrate 20 after forming the scintillator 34 is not necessary as described above. The vapor deposition substrate 20 in this aspect is an example of the first support body according to claim 6.

Next, the scintillator 34 will be described. The scintillator 34 irradiates the irradiation surface 12 of the casing 14 that has passed through the body of the subject, and absorbs the radiation X that has been transmitted through the top plate 16 and the radiation detection unit (TFT substrate) 42 of the casing 14. And emit light. In general, as the scintillator, for example, a material such as CsI: Tl (cesium iodide added with thallium)), CsI: Na (sodium-activated cesium iodide), GOS (Gd ₂ O ₂ S: Tb), or the like may be used. it can.

  However, in this embodiment, as shown in FIG. 3 as an example, the scintillator 34 is formed with a columnar crystal region composed of columnar crystals 34A on the radiation incident / light emission side (radiation detection unit 42). A non-columnar crystal region composed of a non-columnar crystal 34B is formed on the opposite side, and a material containing CsI is used as the scintillator 34, and the material is vapor-deposited on the vapor deposition substrate 20, so that A scintillator 34 in which columnar crystal regions are formed is obtained. In addition, as the vapor deposition substrate 20, a material having high heat resistance is desirable. For example, aluminum is preferable from the viewpoint of low cost. In the scintillator 34 according to the present embodiment, the average diameter of the columnar crystals 34A is approximately uniform along the longitudinal direction of the columnar crystals 34A.

  As described above, the scintillator 34 has a structure in which a columnar crystal region and a non-columnar crystal region are formed, and a columnar crystal region made of the columnar crystal 34A that can obtain highly efficient light emission is disposed on the radiation detection unit 42 side. Thus, the light generated by the scintillator 34 travels through the columnar crystal 34A and is emitted to the radiation detection unit 42, and the diffusion of the light emitted to the radiation detection unit 42 side is suppressed, so that it is detected by the electronic cassette 10. The blur of the radiation image is suppressed. Further, the light reaching the deep part (non-columnar crystal region) of the scintillator 34 is also reflected by the non-columnar crystal 34B toward the radiation detection unit 42 side, so that the amount of light incident on the radiation detection unit 42 (in the scintillator 34). The detection efficiency of the emitted light is improved.

  Further, as described above, since the scintillator 34 and the vapor deposition substrate 20 are deformed (curved) so that the light emitting surface side is convex, the columnar crystal 34A of the scintillator 34 is more specifically shown in FIG. As schematically shown, the average interval between adjacent columnar crystals 34A in the vicinity of the tip of the columnar crystal 34A is larger than the average interval between adjacent columnar crystals 34A in the vicinity of the base of the columnar crystal 34A.

  When the thickness of the columnar crystal region located on the radiation incident side of the scintillator 34 is t1, and the thickness of the non-columnar crystal region located on the vapor deposition substrate 20 side of the scintillator 34 is t2, t1 and t2 have the following relationship: It is preferable to satisfy the formula.

0.01 ≦ (t2 / t1) ≦ 0.25
When the thickness t1 of the columnar crystal region and the thickness t2 of the non-columnar crystal region satisfy the above relational expression, a region that has high luminous efficiency and prevents light diffusion (columnar crystal region), and a region that reflects light (noncolumnar) The ratio of the crystal region) along the thickness direction of the scintillator 34 becomes a suitable range, and the light emission efficiency of the scintillator 34, the detection efficiency of the light emitted by the scintillator 34, and the resolution of the radiation image are improved. If the thickness t2 of the non-columnar crystal region is too thick, the region with low luminous efficiency increases and the sensitivity of the electronic cassette 10 is reduced. Therefore, (t2 / t1) is more preferably in the range of 0.02 or more and 0.1 or less. .

  In the above description, the scintillator 34 having a structure in which the columnar crystal region and the non-columnar crystal region are continuously formed has been described. For example, instead of the non-columnar crystal region, a light reflection layer made of aluminum or the like is provided, and the columnar crystal region is formed. Only a crystal region may be formed, or another structure may be used.

  Next, the radiation detection unit 42 will be described. The radiation detection unit 42 detects light emitted from the light emission side of the scintillator 34. As shown in FIG. 4, a photoelectric conversion unit 72 composed of a photodiode (PD: PhotoDiode) or the like, a thin film transistor (TFT: As shown in FIG. 5, a plurality of pixel portions 74 each having a thin film transistor 70 and a storage capacitor 68 are formed in a matrix on an insulating substrate 64 having a flat plate shape and a rectangular outer shape in plan view. TFT active matrix substrate (hereinafter referred to as “TFT substrate”).

  In this embodiment, the radiation detection unit (TFT substrate) 42 is arranged on the radiation irradiation surface side of the scintillator 34. However, the scintillator and the light detection detection unit (radiation detection unit 42) are arranged in such a positional relationship. This method is called “surface reading method (ISS: Irradiation Side Sampling)” (configuration corresponding to the invention of claim 10). Since the scintillator emits light more strongly on the radiation incident side, the surface reading method (ISS) in which the light detector (radiation detector) is arranged on the radiation incident side of the scintillator is the light detector (radiation) on the side opposite to the radiation incident side of the scintillator. Since the light detection unit and the light emission position of the scintillator are closer than the “PSS (Penetration Side Sampling)” where the detector is placed, the resolution of the radiographic image obtained by imaging is high, and the light detection unit Increasing the amount of light received by the (radiation detection unit) results in improved sensitivity of the radiation detection panel (electronic cassette).

The photoelectric conversion unit 72 is configured such that a photoelectric conversion film 72C that absorbs light emitted from the scintillator 34 and generates charges according to the absorbed light is disposed between the lower electrode 72A and the upper electrode 72B. Yes. The lower electrode 72A is preferably made of a conductive material that is transparent at least with respect to the emission wavelength of the scintillator 34, because the light emitted from the scintillator 34 needs to enter the photoelectric conversion film 72C. It is preferable to use a transparent conductive oxide (TCO) that has a high transmittance for visible light and a small resistance value. Although a metal thin film such as Au can be used as the lower electrode 72A, the TCO is preferable because it tends to increase the resistance value when an optical transmittance of 90% or more is obtained. For example, ITO, IZO, AZO, FTO, SnO ₂ , TiO ₂ , ZnO ₂ or the like is preferably used, and ITO is most preferable from the viewpoint of process simplicity, low resistance, and transparency. The lower electrode 72A may have a single configuration common to all the pixel portions, or may be divided for each pixel portion.

  The photoelectric conversion film 72C absorbs the light emitted from the scintillator 34 and generates a charge corresponding to the absorbed light. The material constituting the photoelectric conversion film 72 </ b> C may be any material that absorbs light and generates charges, and for example, amorphous silicon, an organic photoelectric conversion material, or the like can be used. When the photoelectric conversion film 72C is made of amorphous silicon, it can be configured to absorb light emitted from the scintillator 34 over a wide wavelength range. However, it is necessary to perform vapor deposition for forming the photoelectric conversion film 72C made of amorphous silicon. If the insulating substrate 64 is made of a synthetic resin, the heat resistance of the insulating substrate 64 may be insufficient.

  On the other hand, when the photoelectric conversion film 72C is made of a material containing an organic photoelectric conversion material, an absorption spectrum showing high absorption mainly in the visible light region is obtained, and light other than light emitted from the scintillator 34 by the photoelectric conversion film 72C is obtained. Since almost no electromagnetic wave is absorbed, it is possible to suppress noise generated when radiation such as X-rays and γ-rays is absorbed by the photoelectric conversion film 72C. In addition, the photoelectric conversion film 72C made of an organic photoelectric conversion material can be formed by attaching an organic photoelectric conversion material on a body to be formed using a droplet discharge head such as an inkjet head. Heat resistance is not required. For this reason, in this embodiment, the photoelectric conversion film 72C of the photoelectric conversion unit 72 is formed of an organic photoelectric conversion material.

  When the photoelectric conversion film 72C is made of an organic photoelectric conversion material, radiation is hardly absorbed by the photoelectric conversion film 72C. Therefore, in the surface reading method (ISS) in which the radiation detection unit 42 is disposed so that the radiation is transmitted, radiation detection is performed. Attenuation of radiation due to transmission through the portion 42 can be suppressed, and a decrease in sensitivity to radiation can be suppressed. Therefore, it is particularly suitable for the surface reading method (ISS) to configure the photoelectric conversion film 72C with an organic photoelectric conversion material.

  The organic photoelectric conversion material constituting the photoelectric conversion film 72 </ b> C preferably has an absorption peak wavelength that is closer to the emission peak wavelength of the scintillator 34 in order to absorb light emitted from the scintillator 34 most efficiently. Ideally, the absorption peak wavelength of the organic photoelectric conversion material matches the emission peak wavelength of the scintillator 34, but if the difference between the two is small, the light emitted from the scintillator 34 can be sufficiently absorbed. . Specifically, the difference between the absorption peak wavelength of the organic photoelectric conversion material and the emission peak wavelength with respect to the radiation of the scintillator 34 is preferably within 10 nm, and more preferably within 5 nm.

  Examples of organic photoelectric conversion materials that can satisfy such conditions include quinacridone-based organic compounds and phthalocyanine-based organic compounds. For example, since the absorption peak wavelength in the visible region of quinacridone is 560 nm, if quinacridone is used as the organic photoelectric conversion material and CsI (Tl) is used as the material of the scintillator 34, the difference in peak wavelength can be made within 5 nm. Thus, the amount of charge generated in the photoelectric conversion film 72C can be substantially maximized.

  The photoelectric conversion film 72C applicable to the radiation detection panel will be specifically described. The electromagnetic wave absorption / photoelectric conversion site in the radiation detection panel is an organic layer including electrodes 72A and 72B and a photoelectric conversion film 72C sandwiched between the electrodes 72A and 72B. More specifically, this organic layer is a part that absorbs electromagnetic waves, a photoelectric conversion part, an electron transport part, a hole transport part, an electron blocking part, a hole blocking part, a crystallization preventing part, an electrode, and an interlayer contact. It can be formed by stacking or mixing improved parts.

  The organic layer preferably contains an organic p-type compound or an organic n-type compound. An organic p-type semiconductor (compound) is a donor organic semiconductor (compound) mainly represented by a hole transporting organic compound, and is an organic compound having a property of easily donating electrons. More specifically, an organic compound having a smaller ionization potential when two organic materials are used in contact with each other. Accordingly, any organic compound having an electron donating property can be used as the donor organic compound. The organic n-type semiconductor (compound) is an acceptor organic semiconductor (compound) mainly represented by an electron transporting organic compound, and is an organic compound having a property of easily accepting electrons. More specifically, the organic compound having the higher electron affinity when two organic compounds are used in contact with each other. Therefore, any organic compound can be used as the acceptor organic compound as long as it is an organic compound having an electron accepting property.

  Since the materials applicable as the organic p-type semiconductor and the organic n-type semiconductor and the configuration of the photoelectric conversion film 72C are described in detail in Japanese Patent Application Laid-Open No. 2009-32854, description thereof is omitted.

  In addition, the photoelectric conversion unit 72 only needs to include at least the electrode pairs 72A and 72B and the photoelectric conversion film 72C, but in order to suppress an increase in dark current, at least one of an electron blocking film and a hole blocking film is provided. It is preferable to provide both.

  The electron blocking film can be provided between the upper electrode 72B and the photoelectric conversion film 72C. When a bias voltage is applied between the upper electrode 72B and the lower electrode 72A, the electron blocking film is applied from the upper electrode 72B to the photoelectric conversion film 72C. An increase in dark current due to injection of electrons can be suppressed. An electron donating organic material can be used for the electron blocking film. The material actually used for the electron blocking film may be selected according to the material of the adjacent electrode and the material of the adjacent photoelectric conversion film 72C, and the electron affinity is 1.3 eV or more from the work function (Wf) of the adjacent electrode material. A material having a large (Ea) and an Ip equivalent to or smaller than the ionization potential (Ip) of the material of the adjacent photoelectric conversion film 72C is preferable. Since the material applicable as the electron donating organic material is described in detail in Japanese Patent Application Laid-Open No. 2009-32854, description thereof is omitted.

  The thickness of the electron blocking film is preferably 10 nm or more and 200 nm or less, more preferably 30 nm or more and 150 nm or less, and particularly preferably, in order to reliably exhibit the dark current suppressing effect and prevent a decrease in photoelectric conversion efficiency of the photoelectric conversion unit 72. It is 50 nm or more and 100 nm or less.

  The hole blocking film can be provided between the photoelectric conversion film 72C and the lower electrode 72A, and when a bias voltage is applied between the upper electrode 72B and the lower electrode 72A, the lower electrode 72A to the photoelectric conversion film 72C. It is possible to suppress the increase of dark current due to injection of holes into the substrate. An electron-accepting organic material can be used for the hole blocking film. The material actually used for the hole blocking film may be selected in accordance with the material of the adjacent electrode and the material of the adjacent photoelectric conversion film 72C, and the ionization is 1.3 eV or more from the work function (Wf) of the adjacent electrode material. It is preferable that the potential (Ip) is large and that the Ea is equal to or larger than the electron affinity (Ea) of the material of the adjacent photoelectric conversion film 72C. Since the material applicable as the electron-accepting organic material is described in detail in Japanese Patent Application Laid-Open No. 2009-32854, description thereof is omitted.

  The thickness of the hole blocking film is preferably 10 nm or more and 200 nm or less, more preferably 30 nm or more and 150 nm or less, particularly preferably, in order to surely exhibit the dark current suppressing effect and prevent a decrease in the photoelectric conversion efficiency of the photoelectric conversion unit 72. Is from 50 nm to 100 nm.

  When the bias voltage is set so that holes move to the lower electrode 72A and electrons move to the upper electrode 72B among the charges generated in the photoelectric conversion film 72C, the electron blocking film and the hole blocking film are used. It is sufficient to reverse the position of. Moreover, it is not essential to provide both the electron blocking film and the hole blocking film, and if any of them is provided, a certain degree of dark current suppressing effect can be obtained.

  In the TFT 70, a gate electrode, a gate insulating film, and an active layer (channel layer) are stacked, and a source electrode and a drain electrode are formed on the active layer at a predetermined interval. The active layer can be formed of any one of, for example, amorphous silicon, amorphous oxide, organic semiconductor material, carbon nanotube, etc., but the material capable of forming the active layer is not limited to these. .

As an amorphous oxide capable of forming an active layer, for example, an oxide containing at least one of In, Ga, and Zn (for example, an In-O system) is preferable, and at least one of In, Ga, and Zn is used. Oxides containing two (eg, In—Zn—O, In—Ga—O, and Ga—Zn—O) are more preferable, and oxides including In, Ga, and Zn are particularly preferable. As the In—Ga—Zn—O-based amorphous oxide, an amorphous oxide whose composition in a crystalline state is represented by InGaO ₃ (ZnO) _m (m is a natural number less than 6) is preferable, and InGaZnO is particularly preferable. ₄ is more preferable. Note that the amorphous oxide capable of forming the active layer is not limited to these.

  Examples of the organic semiconductor material capable of forming an active layer include, but are not limited to, phthalocyanine compounds, pentacene, vanadyl phthalocyanine, and the like. In addition, about the structure of a phthalocyanine compound, since it demonstrates in detail by Unexamined-Japanese-Patent No. 2009-212389, description is abbreviate | omitted.

  If the active layer of the TFT 70 is formed of any one of an amorphous oxide, an organic semiconductor material, a carbon nanotube, etc., the radiation such as X-rays is not absorbed, or even if it is absorbed, the amount remains very small. Generation of noise in the output unit 104 can be effectively suppressed.

  Further, when the active layer is formed of carbon nanotubes, the switching speed of the TFT 70 can be increased, and the degree of light absorption in the visible light region of the TFT 70 can be reduced. In addition, when the active layer is formed of carbon nanotubes, the performance of the TFT 70 is remarkably deteriorated just by mixing a very small amount of metallic impurities into the active layer. Therefore, it must be used for forming the active layer.

  In addition, since the film | membrane formed with the organic photoelectric conversion material and the film | membrane formed with the organic-semiconductor material have sufficient flexibility, the photoelectric conversion film 72C formed with the organic photoelectric conversion material, and an active layer are made into organic. If the TFT 70 made of a semiconductor material is combined, it is not always necessary to increase the rigidity of the radiation detection unit 42 in which the weight of the patient's body is added as a load.

  Further, the insulating substrate 64 may be any substrate as long as it has optical transparency and little radiation absorption. Here, both the amorphous oxide constituting the active layer of the TFT 70 and the organic photoelectric conversion material constituting the photoelectric conversion film 72C of the photoelectric conversion portion 72 can be formed at a low temperature. Therefore, the insulating substrate 64 is not limited to a substrate having high heat resistance such as a semiconductor substrate, a quartz substrate, and a glass substrate, and a flexible substrate made of synthetic resin, aramid, or bionanofiber can also be used. Specifically, flexible materials such as polyesters such as polyethylene terephthalate, polybutylene phthalate, polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, polycycloolefin, norbornene resin, poly (chlorotrifluoroethylene), etc. A conductive substrate can be used. By using such a flexible substrate made of synthetic resin, it is possible to reduce the weight, which is advantageous for carrying around, for example. The insulating substrate 64 includes an insulating layer for ensuring insulation, a gas barrier layer for preventing permeation of moisture and oxygen, an undercoat layer for improving flatness or adhesion to electrodes, and the like. May be provided.

  Since aramid can be applied at a high temperature process of 200 ° C. or more, the transparent electrode material can be cured at a high temperature to reduce the resistance, and can be applied to automatic mounting of a driver IC including a solder reflow process. Moreover, since aramid has a thermal expansion coefficient close to that of ITO (indium tin oxide) or a glass substrate, there is little warping after manufacturing and it is difficult to break. In addition, aramid can make a substrate thinner than a glass substrate or the like. Note that the insulating substrate 64 may be formed by stacking an ultrathin glass substrate and aramid.

  The bionanofiber is a composite of a cellulose microfibril bundle (bacterial cellulose) produced by bacteria (Acetobacter Xylinum) and a transparent resin. The cellulose microfibril bundle has a width of 50 nm and a size of 1/10 of the visible light wavelength, and has high strength, high elasticity, and low thermal expansion. By impregnating and curing a transparent resin such as an acrylic resin or an epoxy resin in bacterial cellulose, a bio-nanofiber having a light transmittance of about 90% at a wavelength of 500 nm can be obtained while containing 60 to 70% of the fiber. Bionanofiber has a low coefficient of thermal expansion (3-7ppm) comparable to silicon crystals, and is as strong as steel (460MPa), highly elastic (30GPa), and flexible, compared to glass substrates, etc. The insulating substrate 64 can be thinned.

  When a glass substrate is used as the insulating substrate 64, the overall thickness of the radiation detection unit (TFT substrate) 42 is, for example, about 0.7 mm. As the substrate 64, a thin substrate made of a light-transmitting synthetic resin is used. As a result, the thickness of the radiation detection part (TFT substrate) 42 as a whole can be reduced to, for example, about 0.1 mm, and the radiation detection part (TFT substrate) 42 can be made flexible. Further, by providing flexibility to the radiation detection unit (TFT substrate) 42, the impact resistance of the electronic cassette 10 is improved, and even when an impact is applied to the electronic cassette 10, it is difficult to be damaged. In addition, plastic resin, aramid, bio-nanofiber, etc. all absorb little radiation, and when the insulating substrate 64 is formed of these materials, the amount of radiation absorbed by the insulating substrate 64 is also reduced. Even if the radiation is transmitted through the radiation detection unit 42 by (ISS), a decrease in sensitivity to radiation can be suppressed. The insulating substrate 64 having flexibility as described above is an example of the second support body according to claim 7.

  Note that it is not essential to use a synthetic resin substrate as the insulating substrate 64 of the electronic cassette 10, and although the thickness of the electronic cassette 10 increases, a substrate made of another material such as a glass substrate is used as the insulating substrate 64. You may make it use as.

  As shown in FIG. 5, the radiation detection unit (TFT substrate) 42 has a plurality of gate wirings 76 extending in a certain direction (row direction) for turning on / off individual TFTs 70, and the certain constants. The charge accumulated in the storage capacitor 68 (and between the lower electrode 72A and the upper electrode 72B of the photoelectric conversion unit 72) extending along the direction (column direction) intersecting with the direction is read out through the on-state TFT 70. For this purpose, a plurality of data wirings 78 are provided. Further, as shown in FIG. 4, a planarizing layer 67 for flattening the TFT substrate is formed at the end of the radiation detection unit (TFT substrate) 42 opposite to the radiation arrival direction. . An adhesive layer 66 is provided between the radiation detection unit (TFT substrate) 42 and the top plate 16, and the radiation detection unit (TFT substrate) 42 is attached to the top plate 16 by the adhesive layer 66. .

  Individual gate lines 76 of the radiation detection unit 42 are connected to a gate line driver 81, and individual data lines 78 are connected to a signal processing unit 83. When radiation that has passed through the subject's body (radiation carrying image information of the subject's body) is applied to the electronic cassette 10, the scintillator 34 starts from the portion corresponding to each position on the irradiation surface 12. The amount of light corresponding to the radiation dose at each position is emitted, and the photoelectric conversion unit 72 of each pixel unit 74 has a magnitude corresponding to the amount of light emitted from the corresponding part of the scintillator 34. This charge is generated, and this charge is stored in the storage capacitor 68 of each pixel unit 74 (and between the lower electrode 72A and the upper electrode 72B of the photoelectric conversion unit 72).

  When charges are accumulated in the storage capacitors 68 of the individual pixel portions 74 as described above, the TFTs 70 of the individual pixel portions 74 are supplied in units of rows by signals supplied from the gate line drivers 81 via the gate wirings 76. The charges stored in the storage capacitor 68 of the pixel unit 74 that is sequentially turned on and the TFT 70 is turned on are transmitted through the data wiring 78 as an analog electric signal and input to the signal processing unit 83. Accordingly, the charges accumulated in the storage capacitors 68 of the individual pixel portions 74 are sequentially read out in units of rows.

  The signal processing unit 83 includes an amplifier and a sample hold circuit provided for each data wiring 78, and an electric signal transmitted through each data wiring 78 is amplified by the amplifier and then held in the sample hold circuit. The In addition, a multiplexer and an A / D (analog / digital) converter are connected in order to the output side of the sample and hold circuit, and the electrical signals held in the individual sample and hold circuits are sequentially (serially) input to the multiplexer. The digital image data is converted by an A / D converter.

  An image memory 90 is connected to the signal processing unit 83, and image data output from the A / D converter of the signal processing unit 83 is sequentially stored in the image memory 90. The image memory 90 has a storage capacity capable of storing image data for a plurality of frames, and image data obtained by imaging is sequentially stored in the image memory 90 every time a radiographic image is captured.

  The image memory 90 is connected to a cassette control unit 92 that controls the operation of the entire electronic cassette 10. The cassette control unit 92 includes a microcomputer, and includes a CPU 92A, a memory 92B including a ROM and a RAM, a nonvolatile storage unit 92C including an HDD (Hard Disk Drive), a flash memory, and the like.

  A wireless communication unit 94 is connected to the cassette control unit 92. The wireless communication unit 94 corresponds to a wireless local area network (LAN) standard represented by IEEE (Institute of Electrical and Electronics Engineers) 802.11a / b / g / n, etc. Control the transmission of various information between them. The cassette control unit 92 can wirelessly communicate with the console 80 (see FIG. 6) via the wireless communication unit 94, and can transmit and receive various types of information to and from the console 80.

  The electronic cassette 10 is provided with a power supply unit 96, and the various electronic circuits (gate line driver 81, signal processing unit 83, image memory 90, wireless communication unit 94, cassette control unit 92, etc.) described above are power supply units. 96 are connected to each other (not shown), and are operated by electric power supplied from the power supply unit 96. The power supply unit 96 incorporates the above-described battery (secondary battery) so as not to impair the portability of the electronic cassette 10, and supplies power from the charged battery to various electronic circuits.

  As shown in FIG. 6, the console 80 is composed of a computer, the CPU 104 that controls the operation of the entire apparatus, the ROM 106 that stores various programs including a control program in advance, the RAM 108 that temporarily stores various data, and various data Are connected to each other via a bus. Further, the communication I / F unit 116 and the wireless communication unit 118 are connected to the bus, the display 100 is connected via the display driver 112, and the operation panel 102 is further connected via the operation input detection unit 114. .

  The communication I / F unit 116 is connected to the radiation generator 84 via the connection terminal 80A, the communication cable 82, and the connection terminal 84A of the radiation generator 84. The console 80 (the CPU 104 thereof) transmits / receives various information such as exposure conditions to / from the radiation generation apparatus 84 via the communication I / F unit 132. The wireless communication unit 118 has a function of performing wireless communication with the wireless communication unit 94 of the electronic cassette 10, and the console 80 (CPU 104) transmits and receives various information such as image data to and from the electronic cassette 10. 118. Further, the display driver 112 generates and outputs signals for displaying various information on the display 100, and the console 80 (CPU 104 of the console 80) displays an operation menu, a captured radiation image, and the like on the display 100 via the display driver 112. Display. The operation panel 102 includes a plurality of keys, and various information and operation instructions are input. The operation input detection unit 114 detects an operation on the operation panel 102 and notifies the CPU 104 of the detection result.

  Further, the radiation generator 84 includes a communication I / F unit 132 that transmits and receives various information such as an exposure condition between the radiation source 130 and the console 80, and an exposure condition (this exposure) received from the console 80. And a radiation source controller 134 for controlling the radiation source 130 based on the conditions (including the tube voltage and tube current information).

  Next, the operation of this embodiment will be described. In the electronic cassette 10 according to this embodiment, the radiation detection part (TFT substrate) 42 and the scintillator 34 are not bonded together, and only the peripheral part is fixed by the fixing agent 22 having flexibility over the entire circumference. For this reason, even if the coefficient of thermal expansion of the material constituting the insulating substrate 64 of the radiation detection unit 42 and the material constituting the vapor deposition substrate 20 of the scintillator 34 are significantly different, any one of the substrates changes with temperature. It is possible to prevent deformation such as warpage.

  When radiographing is performed using the electronic cassette 10, the radiographer (for example, a radiographer or the like) can place the radiographing surface 12 side between the radiographing target portion of the subject's body and the base. The electronic cassette 10 is inserted upward and the preparatory work for adjusting the orientation and position is performed. Here, when the electronic cassette 10 is inserted between the body of the subject and the base, the weight of the subject's body is applied as a load mainly to the central portion of the top plate 16 of the electronic cassette 10. The load is transmitted from the top plate 16 to the scintillator 34 and the vapor deposition substrate 20 via the radiation detection unit 42.

  Thereby, as shown in FIG. 2B as an example, the top plate 16, the radiation detector 42, the scintillator 34, and the vapor deposition substrate 20 that are curved so as to be convex toward the radiation arrival side are mainly in the center. It is elastically deformed in a direction in which the degree of curvature is reduced by the load applied to the portion, and is maintained in a substantially flat state while the load is applied (that is, while radiographic images are being taken). The columnar crystals 34A of the scintillator 34 are adjacent columnar crystals near the tip of the columnar crystal 34A as shown in FIG. 7B as an example, as the scintillator 34 and the vapor deposition substrate 20 become substantially flat. The average interval of 34A becomes small.

  However, in the scintillator 34, when no load is applied, the average interval between adjacent columnar crystals 34A in the vicinity of the tip of the columnar crystal 34A is larger than the average interval between adjacent columnar crystals 34A in the vicinity of the base of the columnar crystal 34A. Therefore, as described above, even when the average interval between the adjacent columnar crystals 34A in the vicinity of the tip of the columnar crystal 34A is reduced by applying a load, the tips of the adjacent columnar crystals 34A are in contact with each other. Doing so is prevented. Therefore, even when a load is applied to the top plate 16, it is possible to prevent the sharpness of the radiographic image to be captured from being lowered by the tips of the adjacent columnar crystals 34A coming into contact with each other.

  On the other hand, when the preparatory work is completed, the photographer operates the operation panel 102 to instruct to start photographing. As a result, the console 80 transmits an instruction signal instructing the start of exposure to the radiation generator 84, and the radiation generator 84 emits radiation from the radiation source 130. Radiation emitted from the radiation source 130 passes through the body of the subject and is irradiated onto the irradiation surface 12 of the electronic cassette 10, and passes through the top plate 16 and the radiation detection unit 42 to reach the irradiation / light emission surface of the scintillator 34. Irradiated. The scintillator 34 absorbs radiation applied to the irradiation / light emission surface, and emits light having a light amount corresponding to the absorbed radiation amount. The light emitted from the scintillator 34 is irradiated on the light receiving surface of the radiation detecting unit 42, and the radiation detecting unit 42 detects the light irradiated on the light receiving surface as an image. The detection result by the radiation detection unit 42 is read as an image signal, converted into image data, and transmitted to the console 80. Thereby, the radiographic image is captured.

  Further, when the radiographic image capturing is completed, the load applied to the top plate 16 of the electronic cassette 10 is removed. Thereby, the top plate 16, the radiation detection part 42, the scintillator 34, and the vapor deposition board | substrate 20 will be restored | restored to the state which is curving so that it may become convex to the radiation arrival side. It should be noted that a sponge (instead of this) is provided between the vapor deposition substrate 20 and the top plate of the base 24 in order to assist the restoration to the curved state so as to be convex toward the radiation arrival side as described above. An elastic member such as a spring may be provided in advance. When such an elastic member is provided, the elastic force of the elastic member acts as a pressing force that presses the radiation detection unit 42, the scintillator 34, and the vapor deposition substrate 20 toward the top plate 16. Regarding the attachment of the radiation detection unit 42, the position of the radiation detection unit 42 can be sufficiently retained by simply attaching the peripheral edge of the radiation detection unit 42 to the top plate 16. Thereby, the workability | operativity at the time of peeling the radiation detection part 42 from the top plate 16 for the purpose of components replacement | exchange etc. is also improved.

  Next, another aspect of the present invention will be described. In the above, the top plate 16 of the electronic cassette 10 is curved with a curvature similar to that of the scintillator 34 and the vapor deposition substrate 20 so that the irradiation surface 12 side is convex, and the radiation detection unit 42 is covered with the inner surface of the top plate 16 over the entire surface. Although the aspect (refer FIG. 2) affixed by adhesion | attachment etc. was demonstrated, it is not restricted to this, As shown in FIG. 8 (A) as an example, the top plate 16 is not curved and the load is not added. The top plate 16 may be configured to be flat in a steady state, and the radiation detection unit 42 may be attached to the inner surface of the top plate 16 only in a region corresponding to the vicinity of the central portion of the irradiation surface 12. In this aspect, when the weight of the subject's body is applied as a load mainly to the central portion of the top plate 16 of the electronic cassette 10 at the time of capturing a radiographic image, as shown in FIG. Is elastically deformed so as to be convex toward the inside of the housing 14, while the radiation detector 42, the scintillator 34, and the vapor deposition substrate 20 are elastically deformed so as to be approximately flat. The embodiment shown in FIG. 8 is also included in the scope of rights of the present invention.

  In the above description, the average diameter of the columnar crystals 34A of the scintillator 34 is approximately uniform along the longitudinal direction of the columnar crystals 34A (see FIG. 3). However, the present invention is not limited to this. As an example, the scintillator 150 shown in FIG. 9 has a taper shape near the tip of the columnar crystal 150A so that the average diameter of the columnar crystal 150A in the vicinity of the tip of the columnar crystal 150A is changed to a columnar shape near the base of the columnar crystal 150A. It is smaller than the average diameter of the crystal 150A. The columnar crystal of the scintillator may be configured as described above. When the columnar crystals of the scintillator are configured as described above, even if the scintillator is not deformed so that the radiation incident / light exit surface side is convex, the average interval between adjacent columnar crystals near the tip of the columnar crystal is Since it is larger than the average interval between adjacent columnar crystals in the vicinity of the base of the columnar crystals, the scintillator need not be deformed so that the radiation incident / light exit surface side is convex. The embodiment shown in FIG. 9 is an example of the invention described in claim 11.

  In the above description, the mode in which the light emitted from the scintillator 34 is detected by the single light detection unit (radiation detection unit 42) has been described. However, the present invention is not limited to this. As an example, in FIG. 10, in addition to the radiation detection unit 42, a radiation detection unit 200 as a light detection unit that detects light emitted from the scintillator 34 is provided between the radiation detection unit 42 and the top plate 16. Shows the configuration. In the radiation detection unit 200, a wiring layer 202 having a patterned wiring and an insulating layer 204 are sequentially formed, and a plurality of sensor units 206 for detecting light emitted from the scintillator 34 and transmitted through the radiation detection unit 42 are formed thereon. Further, an adhesive layer 66 that also serves to protect the radiation detection unit 200 is formed on the upper layer of the sensor unit 206. In addition, the thickness of the radiation detection part 200 is about 0.05 mm, for example.

  The sensor unit 206 includes an upper electrode 210A and a lower electrode 210B, and a photoelectric conversion film 210C that absorbs light from the scintillator 34 and generates a charge is disposed between the upper electrode 210A and the lower electrode 210B. ing. As the sensor unit 206 (photoelectric conversion film 210C), it is possible to apply a PIN type or MIS type photodiode using amorphous silicon, but in this embodiment, the same as the photoelectric conversion film 72C of the photoelectric conversion unit 72. In addition, the photoelectric conversion film 210C is made of an organic photoelectric conversion material. This makes it possible to form the photoelectric conversion film 210C by adhering the organic photoelectric conversion material onto the object to be formed using a droplet discharge head such as an inkjet head, and the insulating substrate 64 has light transmittance. It is possible to use a thin substrate made of a synthetic resin.

  The detection result of the radiation dose by the sensor unit 206 is read out through a signal processing unit (not shown) connected to the electrodes 210A and 210B, and for example, detection of radiation irradiation start / end timing to the electronic cassette 10 or electronic cassette 10 is used to detect the integrated value of the radiation dose to 10. Note that the detection (imaging) of the radiation image is performed by the radiation detection unit 42. Therefore, the sensor unit 206 of the radiation detection unit 200 has a larger arrangement pitch (lower arrangement density) than the pixel unit 74 of the radiation detection unit 42. In addition, the light receiving area of the single sensor unit 206 may have a size corresponding to several to several hundreds of the pixel units 74 of the radiation detection unit 42.

  In addition, it is needless to say that the configuration of the electronic cassette 10 as the radiation detection panel according to the present invention described in the above embodiment is an example, and can be appropriately changed without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Electronic cassette 14 Case 16 Top plate 20 Deposition board 34 Scintillator 34A Columnar crystal 42 Radiation detection part 150 Scintillator

Claims (11)

The light emission side on which a plurality of columnar crystals are erected is arranged in the casing in a direction facing the inner surface of the top plate of a box-shaped casing, and absorbs irradiated radiation from the light emission side. A scintillator that emits light;
The light is emitted from the light emission side of the scintillator and is added to the top plate while being sandwiched between the inner surface of the top plate and the light emission side of the scintillator. A light detector for transmitting a load to the scintillator;
Including
The scintillator is a radiation detection panel in which an average interval between adjacent columnar crystals in the vicinity of the tip of the columnar crystal is larger than an average interval between adjacent columnar crystals in the vicinity of the base of the columnar crystal.   The radiation according to claim 1, wherein the light detection unit is affixed to an inner surface of the top plate, and the light detection unit and the light emission side of the scintillator are in contact with each other without being bonded together. Detection panel.   The scintillator has a flat plate shape, and is deformed so that one of the top surface and the bottom surface is a light emitting surface and the light emitting surface side is convex, so that the columnar crystals adjacent to each other in the vicinity of the tip portion of the columnar crystals are formed. 3. The radiation detection panel according to claim 1, wherein an average interval is larger than an average interval between adjacent columnar crystals in the vicinity of a base portion of the columnar crystals.   The radiation detection panel according to any one of claims 1 to 3, wherein the scintillator has an average diameter of the columnar crystals substantially uniform along a longitudinal direction of the columnar crystals.   The scintillator is formed on the first support so that a surface of the top surface and the bottom surface opposite to the light emitting surface is in contact with the flat first support, and the first support is The radiation detection panel according to claim 3, wherein the deformation is caused by bending.   The first support has a characteristic that the shape changes according to temperature, and is substantially flat in a temperature range when the scintillator is formed on the first support, and the radiation detection panel The radiation detection panel according to claim 5, wherein the curvature is generated in a temperature range when radiation detection is performed.   The radiation detection panel according to claim 1, wherein the flat plate-like second support body on which the light detection unit is formed has flexibility.   The radiation detection panel according to claim 7, wherein the photoelectric conversion part constituting the light detection part is made of a material containing an organic photoelectric conversion material, and the active layer of the switching element constituting the light detection part is made of a material containing an organic semiconductor material. .   Each of the scintillator and the light detection unit is formed in a flat plate shape, and each peripheral part is fixed so as to prevent relative movement in a direction substantially parallel to the top plate, and the scintillator and the light detection unit The radiation detection panel according to claim 2, wherein a region other than the peripheral portion is abutted without being bonded.   The radiation is incident on the radiation detection panel from the top plate side of the casing, and the radiation incident from the top plate side passes through the light detection unit and is irradiated to the scintillator. The radiation detection panel according to any one of 9.   In the scintillator, the average diameter of the columnar crystal in the vicinity of the tip of the columnar crystal is smaller than the average diameter of the columnar crystal in the vicinity of the base of the columnar crystal. The average interval between the columnar crystals adjacent to each other is larger than the average interval between the columnar crystals adjacent to each other in the vicinity of the base portion of the columnar crystal. The radiation detection panel according to item.

Images