JP2012202735A - Radiation imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation imaging apparatus which does not cause an increase in the weight of the whole apparatus and suppress the occurrence of image irregularity caused by heat generation in the cabinet.SOLUTION: A radiation imaging apparatus includes first heat transfer means (reflective layer 240, deposition substrate 240, or flat plate-like member 262) which thermally connect between heat generation sources of an electronic cassette 20A (power supply unit 94, driving IC 124, reading IC 128, or electronic component 132) and a radiation conversion panel 116 and transfers heat generation from the heat generation source through surface contact to the radiation conversion panel 116.

Description

  The present invention relates to a radiation imaging apparatus including a radiation conversion panel that converts radiation into a radiation image.

  2. Description of the Related Art Conventionally, in the medical field, a radiation imaging apparatus (hereinafter also referred to as “electronic cassette”) that captures a radiation image of a subject by detecting radiation transmitted through the subject has been used. In the electronic cassette, in order to improve portability, a radiation conversion panel that converts radiation into a radiation image and a power supply unit such as a battery that supplies power to the radiation conversion panel are housed in a housing.

  This radiation conversion panel may be composed of, for example, a scintillator that converts radiation into electromagnetic waves of other wavelengths such as visible light, and a photoelectric conversion layer that converts the electromagnetic waves converted by the scintillator into a radiation image. Further, considering the weight reduction of the device and the matching of spectral sensitivity characteristics, as an example of implementation of the radiation conversion panel, cesium iodide (CsI) as a scintillator and a-Si (amorphous silicon) as a photoelectric conversion layer A combination with can be considered.

  However, as shown in FIG. 19A, the scintillator's sensitivity to radiation decreases due to the temperature rise of the scintillator, so that the image quality of the radiographic image may decrease. When the scintillator is made of gadolinium oxide sulfa (GOS), as shown in FIG. 19B, the sensitivity change with respect to the temperature rise of the scintillator is extremely small. When the photoelectric conversion layer is made of a-Si, as shown in FIG. 19C, the electromagnetic wave of the photoelectric conversion element (photodiode) constituting the photoelectric conversion layer is caused by the temperature rise of the photoelectric conversion layer. There is a possibility that the image quality of the radiographic image is lowered due to the increase in sensitivity to. In order to eliminate the above-mentioned concerns, various heat countermeasure techniques have been proposed for the inside of the casing of the electronic cassette.

  In Patent Documents 1 and 2, it is possible to suppress heat transfer to the photoelectric conversion element and the TFT by providing a heat conductive material for thermally coupling the housing and the IC included therein. Is described.

  Patent Document 3 describes that the change in sensitivity of the scintillator caused by radiation irradiation can be reduced by heating the scintillator made of CsI with a heating device.

Japanese Patent No. 3957803 Japanese Patent No. 4018725 JP 2003-107163 A

  However, in the configuration of the apparatus disclosed in Patent Documents 1 and 2, the temperature of the edge portion (site close to the position where the heat conducting material is disposed) of the radiation conversion panel is lowered, and the central portion (arrangement of the heat conducting material is disposed). The temperature of the part far from the position tends to increase. That is, since the temperature distribution of the radiation conversion panel becomes non-uniform, the sensitivity distribution of the radiation conversion panel becomes non-uniform, and as a result, there is a problem that image unevenness occurs in the obtained radiographic image.

  Moreover, if the heating apparatus of patent document 3 is accommodated in a housing | casing, there existed a subject that the weight of an electronic cassette increased and the portability of this electronic cassette fell on the contrary.

  The present invention has been made to solve the above-described problem, and does not increase the weight of the entire apparatus, and can suppress the occurrence of image unevenness due to heat generation inside the housing. The purpose is to provide.

  The radiation imaging apparatus according to the present invention is an apparatus including a radiation conversion panel that converts radiation into a radiation image, and thermally couples between a heat generation source of the radiation imaging apparatus and the radiation conversion panel. It has the 1st heat transfer means which transmits the heat_generation | fever from the said heat generating source by the surface contact with respect to a conversion panel, It is characterized by the above-mentioned.

  As described above, since the heat generation source of the radiation imaging apparatus and the radiation conversion panel are thermally coupled, the heat generated by the operation of the apparatus can be used, and a separate heating apparatus is not necessary. . Further, since the heat generation from the heat generation source is transmitted by surface contact with the radiation conversion panel, the temperature distribution of the radiation conversion panel becomes substantially uniform and the sensitivity distribution of the radiation conversion panel becomes substantially uniform. Accordingly, it is possible to suppress the occurrence of image unevenness due to heat generation inside the housing without increasing the weight of the entire apparatus.

  The heat source preferably includes at least one of an electronic component used for operation control of the radiation conversion panel and a power supply unit that supplies power to the radiation conversion panel. This is efficient because heat is received from the circuit board or the power supply unit that generates a large amount of heat during normal operation of the apparatus.

  Furthermore, it is preferable that the first heat transfer means is a flat plate member that is in surface contact with one surface of the radiation conversion panel. Thereby, heat can be transmitted substantially uniformly to the radiation conversion panel with a simple configuration.

  Furthermore, it is preferable to further have a second heat transfer means that enables a thermal short circuit between the heat source and the radiation conversion panel. Thereby, heat can be more efficiently transferred.

  Furthermore, it is preferable that the second heat transfer means is an insertion member interposed between the heat generation source and the radiation conversion panel. Thereby, heat can be transmitted to the radiation conversion panel with a simple configuration.

  Furthermore, it is preferable to further have a moving means for detachably moving the insertion member. Thereby, the timing which supplies heat to a radiation conversion panel is controllable.

  Furthermore, it is preferable that the moving means insert the insertion member at least within an imaging time by the radiation. Thereby, the sensitivity characteristic of a radiation conversion panel can be stabilized in the imaging time of a radiographic image.

  Further, the radiation conversion panel includes a scintillation layer that converts the radiation into electromagnetic waves of other wavelengths, and a photoelectric conversion layer that converts the electromagnetic waves converted by the scintillation layer into the radiation image. The panel is preferably arranged in the order of the photoelectric conversion layer and the scintillation layer with respect to the radiation irradiation side.

  Furthermore, it is preferable that the scintillation layer includes a substrate and a scintillator crystal formed on the substrate.

  Furthermore, the scintillator crystal is preferably made of CsI. Thereby, a radiographic image can be acquired in the state where the electric charge captured by the deep trap of the photoelectric layer is discharged.

  Furthermore, the first heat transfer means is preferably the substrate. Thereby, it can implement | achieve, without providing a different member, and the efficiency of heat transfer improves.

  Further, it is preferable that the first heat transfer means transfers heat generated from the heat source by contacting the radiation conversion panel on a surface opposite to the radiation irradiation side. Thereby, heat can be directly transferred to the scintillation layer.

  Furthermore, the photoelectric conversion layer is preferably composed of an a-Si photoelectric conversion element. Thereby, a radiation image can be acquired under the state where the electric charge captured by the shallow trap of the photoelectric layer is discharged. Further, when a mechanism for realizing a so-called light reset method is incorporated in the radiation imaging apparatus, the irradiation amount of the reset light to the photoelectric conversion layer can be reduced. In other words, it is possible to suppress the local temperature rise by making the temperature distribution of the radiation conversion panel substantially uniform, and it is difficult to form traps that are normally formed in the photoelectric conversion layer due to light emission of the scintillation layer. It is not necessary to increase the amount of light irradiation excessively, and can be kept to a minimum.

  Furthermore, it is preferable to further have a heat insulating means for blocking heat radiation to the outside of the housing. Thereby, more heat generation inside the housing can be used, which is more efficient.

  Furthermore, it is preferable that the said heat insulation means is a heat insulation member provided in the inner wall of the said housing | casing. Thereby, heat can be transmitted to the radiation conversion panel with a simple configuration.

  According to the radiation imaging apparatus of the present invention, since the heat generation source of the radiation imaging apparatus and the radiation conversion panel are thermally coupled, the heat generated by the operation of the apparatus can be used. A different heating device is not required. Further, since the heat generation from the heat generation source is transmitted by surface contact with the radiation conversion panel, the temperature distribution of the radiation conversion panel becomes substantially uniform and the sensitivity distribution of the radiation conversion panel becomes substantially uniform. Accordingly, it is possible to suppress the occurrence of image unevenness due to heat generation inside the housing without increasing the weight of the entire apparatus.

1 is a configuration diagram of a radiation imaging system to which an electronic cassette according to a first embodiment is applied. It is a perspective view of the electronic cassette of FIG. It is a disassembled perspective view of the housing | casing of FIG. It is sectional drawing along the IV-IV line of FIG. It is sectional drawing along the VV line of FIG. It is sectional drawing along the VI-VI line of FIG. FIG. 7A and FIG. 7B are graphs showing the relationship between cumulative dose and sensitivity in a scintillator made of CsI. FIG. 7C is a graph showing the relationship between storage time and sensitivity in a high temperature state in a scintillator made of CsI. FIG. 8A is a graph showing the relationship between a single dose and sensitivity. FIG. 8B is a graph showing the relationship between elapsed days and sensitivity change. 9A and 9B are enlarged cross-sectional views showing the internal configuration of the radiation conversion panel and the like. It is a block diagram of the electronic cassette of FIG. 2 is a flowchart for explaining imaging of a subject using the electronic cassette of FIG. 1. It is sectional drawing along the XII-XII line | wire of the electronic cassette concerning a 1st modification. It is an expanded sectional view showing internal composition, such as a radiation conversion panel with which an electronic cassette concerning a 2nd modification is provided. 14A and 14B are schematic explanatory diagrams illustrating an example of a moving mechanism of an insertion member of an electronic cassette according to a third modification. It is a perspective view of the electronic cassette concerning a 2nd embodiment. FIG. 16 is a perspective view of the electronic cassette of FIG. 15. It is a perspective view of the electronic cassette concerning a 3rd embodiment. It is a disassembled perspective view of the housing | casing of FIG. FIG. 19A is a graph showing the relationship between temperature and sensitivity in a scintillator made of CsI. FIG. 19B is a graph showing the relationship between temperature and sensitivity in a scintillator made of GOS. FIG. 19C is a graph showing the relationship between temperature and sensitivity in a photoelectric conversion element made of a-Si.

  A radiation imaging apparatus according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[Description of Configuration of Radiation Imaging Apparatus According to First Embodiment]
First, an electronic cassette 20A as a radiation imaging apparatus according to the first embodiment will be described with reference to FIGS.

  FIG. 1 is a configuration diagram of a radiation imaging system 10 incorporating an electronic cassette 20A according to the first embodiment.

  The radiation imaging system 10 detects a radiation source 18 that irradiates radiation 16 and a radiation 16 that has passed through the subject 14 and converts it to a radiation image for a patient who is a subject 14 lying on an imaging table 12 such as a bed. An electronic cassette 20A, a console 22 that controls the radiation source 18 and the electronic cassette 20A, and a display device 24 that displays a radiation image are provided.

  Between the console 22, the electronic cassette 20A and the display device 24, for example, UWB (Ultra Wide Band), IEEE802.60. Signals are transmitted / received by wireless LAN (Local Area Network) such as a / b / g / n or wireless communication using millimeter waves or the like. Note that signals may be transmitted and received by wired communication using a cable.

  The console 22 is connected to a radiology information system (RIS) 26 that centrally manages radiographic images and other information handled in the radiology department in the hospital. The RIS 26 is used to comprehensively manage medical information in the hospital. A medical information system (HIS) 28 to be managed is connected.

  FIG. 2 is a perspective view of the electronic cassette 20A shown in FIG.

  The electronic cassette 20 </ b> A has a substantially rectangular (hexahedron) casing 29 disposed between the imaging table 12 and the subject 14.

  The housing 29 is a monocoque housing having a hollow rectangular tube-shaped housing body 30 and two lid members 32 and 34 for closing the opening of the housing body 30 from both sides. For example, the entire housing 29 is subjected to the housing 29 falling, the load from the subject 14, and the impact from the outside. The housing 29 (the housing body 30 and the lid members 32 and 34 thereof) is formed of a material such as carbon or plastic that can transmit the radiation 16.

  The upper surface of the housing 29 on which the subject 14 lies is an irradiation surface 36 to which the radiation 16 is irradiated. A guide line 38 indicating the imaging region and imaging position of the subject 14 is formed on the irradiation surface 36, and an outer frame of the guide line 38 is an imageable region 40 indicating the maximum irradiation range (irradiation field) of the radiation 16. Yes. Further, the center position of the guide line 38 (intersection of two guide lines 38 intersecting in a cross shape) is the center position of the imageable area 40.

  As shown in FIGS. 2 and 3, among the four side surfaces 42 a to 42 d constituting the housing main body 30, a hollow portion 41 is formed between the side surface 42 a and the side surface 42 b along the x direction. The housing 29 is configured by closing the opening 44 a on the side surface 42 a communicating with the lid member 32 and closing the opening 44 b on the side surface 42 b communicating with the hollow portion 41 with the lid member 34. Therefore, the housing 29 includes the irradiation surface 36, the side surface 52 of the lid member 32, the side surface 81 of the lid member 34, the two side surfaces 43 and 45 including the two side surfaces 42c and 42d of the housing body 30, and the housing body. It is configured as a hexahedron having a bottom surface 46 including 30 bottom surfaces 47.

  On the side surface 52 on the x2 direction side of the lid member 32, a power switch 54 for activating the electronic cassette 20A, a display (remaining amount notification unit) 56 for displaying various information, and an input of an AC adapter for charging from the outside A terminal 58, a USB (Universal Serial Bus) terminal 60 as an interface means capable of transmitting / receiving information to / from an external device, a card slot 64 for loading a memory card 62 such as a PC card, and the electronic cassette 20A An indicator (remaining amount notification unit) 66 such as an LED for displaying various situations is provided.

  The input terminal 58 is used when charging the electronic cassette 20A to a cradle (not shown), and is not used when imaging the subject 14 using the electronic cassette 20A as shown in FIG. Further, as will be described later, when the electronic cassette 20A secures the amount of power necessary for imaging by exchanging the power supply unit, the above-described input terminal 58 is unnecessary.

  Furthermore, in the electronic cassette 20 </ b> A, the indicator 66 and the display 56 are disposed. However, the display 66 can substitute for the display function of the indicator 66, thereby making the indicator 66 unnecessary. Moreover, the display 56 can be made unnecessary by the indicator 66 acting as a part of the display function on the display 56.

  The lid member 32 includes a side surface 52 and a power source switch 54, a display 56, an input terminal 58, a USB terminal 60, a card slot 64, and an indicator 66, and a lid body 68 on the x1 direction side of the lid body 68. The insertion portion 70 is formed and can be fitted into the opening portion 44a, and the engagement piece 72 protrudes from both ends along the y direction of the insertion portion 70 toward the opening portion 44a. Further, on the outer side surfaces of the two engaging pieces 72 (on the left engaging piece 72 in FIG. 3, the side surface in the y1 direction and on the right engaging piece 72 the side surface in the y2 direction), an engaging convex portion 74 is formed. On the opening 44a side of the inner wall of the housing body 30, an engagement recess 76 that can be engaged with the engagement projection 74 is formed.

  Accordingly, the lid member 32 is advanced in the x1 direction, the opening 44a and the insertion portion 70 are fitted, and the engagement convex portions 74 of the two engagement pieces 72 that have entered the hollow portion of the housing body 30 When the engaging recesses 76 are respectively engaged, the opening 44 a can be closed by the lid member 32 in a state where the lid member 32 and the housing body 30 are integrated.

  On the other hand, the lid member 34 has substantially the same configuration as the lid member 32 described above except that the power switch 54, the display 56, the input terminal 58, the USB terminal 60, the card slot 64, and the indicator 66 are not provided. is there. That is, the lid member 34 is formed on the x2 direction side of the lid main body 80 and the lid main body 80 having substantially the same shape as the lid main body 68 and having the side surface 81 in the x1 direction facing the side surface 52, and is formed in the opening 44b. The insertion portion 82 can be fitted, and the engagement piece 84 protrudes from both ends of the insertion portion 82 along the y direction toward the opening 44b. Further, the engaging protrusions 86 are also formed on the outer surfaces of the two engaging pieces 84 (the side surface in the y1 direction in the left side engaging piece 84 and the side surface in the y2 direction in the right side engaging piece 84 in FIG. 3). An engagement recess 88 that can engage with the engagement protrusion 86 is formed on the inner wall 44 of the housing body 30 on the opening 44b side.

  Accordingly, as in the case of the lid member 32, the lid member 34 is advanced in the x2 direction, the opening 44b and the insertion portion 82 are fitted, and the two engagements that have entered the hollow portion of the housing body 30 are made. When the engaging convex portion 86 and the engaging concave portion 88 of the piece 84 are engaged with each other, the opening 44 b can be closed by the lid member 34 in a state where the lid member 34 and the housing body 30 are integrated.

  4 to 6 are cross-sectional views of the electronic cassette 20 </ b> A illustrating the inside of the housing 29.

  A chamber 110 that is a hollow portion 41 is formed in the housing 29 by closing the openings 44 a and 44 b of the housing body 30 with the two lid members 32 and 34, respectively.

  The irradiation surface 36 includes a top plate 200 made of a material such as carbon, and a protection member 202 made of a material such as polycarbonate for protecting the top plate 200. The upper inner wall 204 of the housing 29 is formed with a two-step concave portion 206 over the entire circumference. Since the two-step recessed portion 206 is provided so that the top plate 200 and the protection member 202 can be fitted, the casing 29 is stacked in the z2 direction in the order of the top plate 200 and the protection member 202. These can be held.

  A base 112 is disposed at the center of the chamber 110, and is fixedly supported by a plurality of support members 210 (two are shown in FIG. 5) extending in the z2 direction from the inner wall 208 on the bottom surface 46 side. Yes.

  On the surface 114 (surface on the irradiation surface 36 side) of the base 112, a radiation conversion panel 116 that converts the radiation 16 that has passed through the irradiation surface 36 side of the housing body 30 and entered the chamber 110 into a radiation image is disposed. Yes.

  The radiation conversion panel 116 preferably has a size corresponding to the imageable region 40 (see FIGS. 2 and 3), and is bonded to the inner wall 214 on the irradiation surface 36 side of the housing body 30 via the adhesive layer 212. It is fixed. For the adhesive layer 212, for example, a non-flammable adhesive (so-called hot melt adhesive) whose main component is a thermoplastic resin or rubber may be used.

  The radiation conversion panel 116 includes a scintillation layer 118 that converts the radiation 16 into electromagnetic waves of other wavelengths such as visible light, and a photoelectric conversion layer 120 that converts the electromagnetic waves converted by the scintillation layer 118 into electric signals. This is a so-called indirect conversion type radiation detector.

  In addition, the scintillation layer 118 and the photoelectric conversion layer 120 may be stacked in a separable state in consideration of generation of warpage due to heat. Alternatively, the photoelectric conversion layer 120 may be directly formed on the scintillation layer 118, or the scintillation layer 118 may be directly formed on the photoelectric conversion layer 120.

  4 to 6 illustrate an ISS (Irradiation Side Sampling) type radiation detector as a surface reading method in which the photoelectric conversion layer 120 and the scintillation layer 118 are arranged in this order along the irradiation direction of the radiation 16. However, it may be a PSS (Penetration Side Sampling) type radiation detector, which is a back surface reading type, arranged in the order of the scintillation layer 118 and the photoelectric conversion layer 120 along the irradiation direction of the radiation 16. As the scintillation layer 118, for example, a scintillator made of cesium iodide (CsI) or gadolinium oxide sulfide (GOS) may be used. Furthermore, in this embodiment, instead of the above-described indirect conversion type radiation detector, a so-called direct conversion type radiation detector that directly converts the radiation 16 into an electric signal without using the scintillation layer 118 may be used. Is possible. In the following description, a case where the ISS type radiation conversion panel 116 is used will be described.

  Considering weight reduction of the apparatus and matching of spectral sensitivity characteristics, as an example of implementation of the radiation conversion panel 116, cesium iodide (CsI) as the scintillation layer 118 and a-Si (amorphous) as the photoelectric conversion layer 120 Combination with silicon) is conceivable. The relationship between the change in the usage environment of the electronic cassette 20A in this case and the effect on the image quality of the radiation image will be described with reference to FIGS. 19A to 19C and FIGS. 7A to 8B.

  When the scintillation layer 118 made of CsI is used for the purpose of reducing the weight of the electronic cassette 20A, as shown in FIG. 19A, the sensitivity of the scintillation layer 118 to the radiation 16 decreases due to the temperature rise of the scintillation layer 118. As a result, there is a possibility that the image quality of the radiation image is degraded.

  Further, as shown in FIG. 7A, the sensitivity of the scintillation layer 118 with respect to the radiation 16 decreases due to an increase in the cumulative exposure dose (cumulative dose) of the radiation 16.

  This is because photodegradation in which many deep traps (defects) are generated in the CsI scintillation layer 118 as the cumulative irradiation amount increases. As a result, in the next imaging, an electromagnetic wave (visible light) converted from the radiation 16 is visible. This is because the light) is captured by the deep trap and cannot reach the photoelectric conversion layer 120. In this case, since it is not known at which location in the scintillation layer 118 the deep trap occurs, unintended local sensitivity change (sensitivity unevenness) in the scintillation layer 118 due to the capture of visible light in the deep trap. ) Occurs. For this reason, for example, if a large number of deep traps are generated, a portion having relatively high sensitivity (a portion where sensitivity unevenness is conspicuous) may locally occur.

  As shown in FIG. 7B, the sensitivity can be lowered gradually with respect to the cumulative dose by increasing the operating temperature T (T1 <T2). On the other hand, as shown in FIG. 7C, the sensitivity recovers when stored in a high temperature state.

  In the scintillation layer 118 made of GOS, as shown in FIG. 19B, the change in sensitivity with respect to the temperature change is small.

  On the other hand, with respect to the photoelectric conversion layer 120, the sensitivity of the photoelectric conversion layer 120 with respect to electromagnetic waves may change due to a temperature change, and the image quality of the radiation image may deteriorate.

  For example, in the photoelectric conversion layer 120 made of a-Si, when visible light having a high light intensity is incident, a dangling bond of Si is increased, and a conductivity is deteriorated, and a Stebler-Wronski effect is generated. . Thereby, the defect density in Si increases and the movement of carriers in the photoelectric conversion layer 120 is hindered. However, the defect density increases with the incidence of visible light, but saturates as the incidence continues. In addition, the defect density decreases with time as heat is applied to Si.

  More specifically, in the photoelectric conversion layer 120, charges are temporarily trapped in a shallow trap generated in an a-Si photoelectric conversion element (photodiode) constituting the photoelectric conversion layer 120. The trap is more likely to occur as the amount of visible light incident on the photodiode is larger (the more radiation 16 is irradiated). Then, at the time of the next imaging, electric charges are excited by visible light incident on the photoelectric conversion element and discharged from a shallow trap. Therefore, in addition to the new charge converted from the visible light, the photoelectric conversion element also outputs the charge discharged from the shallow trap as an electrical signal corresponding to the radiation image. In this case, since it is not known which photoelectric conversion element in the photoelectric conversion layer 120 has a shallow trap, unintentional local sensitivity of the photoelectric conversion layer 120 due to discharge of electric charge from the shallow trap. Increase (sensitivity unevenness) occurs.

  In addition, if the current imaging is irradiation of radiation 16 with a large dose, a large number of deep traps are generated in the scintillation layer 118 and a large number of shallow traps are also generated in the photoelectric conversion layer 120, and electric charges are generated in these shallow traps. Captured temporarily. For this reason, as shown in FIG. 8A, in the next imaging, a large sensitivity is caused by the generation of a portion having a relatively high sensitivity in the scintillation layer 118 due to the generation of a deep trap and the discharge of charges trapped in a shallow trap. It becomes a change Δ, and apparently the sensitivity of the radiation conversion panel 116 is greatly increased.

  As described above, in the radiation conversion panel 116 including the CsI scintillation layer 118 and the a-Si photoelectric conversion layer 120, when the irradiation amount of the radiation 16 in the current imaging is large, In particular, there is a risk that image sensitivity of the radiographic image becomes conspicuous due to increased sensitivity. Further, when a deep trap occurs in CsI and a shallow trap occurs in a-Si, it takes several days until the large sensitivity change Δ is eliminated as shown in FIG. 8B.

  As described above, in the radiation conversion panel 116, since the image quality of the radiation image may be deteriorated due to the sensitivity change caused by the temperature change or the image unevenness caused by the local sensitivity change, it is desirable that the sensitivity can be recovered by heating. . However, if a heating device for heating the radiation conversion panel 116 is built in the housing 29, the weight of the electronic cassette 20A may increase and the portability may decrease.

  Therefore, in the first embodiment, a configuration is adopted in which the change in sensitivity is suppressed by heating the entire surface of the radiation conversion panel 116 substantially uniformly using heat generated by the operation of the electronic cassette 20A. Hereinafter, the internal structure of the electronic cassette 20A will be described with reference to FIGS.

  As shown in FIG. 6, on the side surface in the y1 direction of the radiation conversion panel 116 (the photoelectric conversion layer 120), a plurality of flexible signals for supplying the photoelectric conversion layer 120 with a control signal for driving the photoelectric conversion layer 120 is provided. Substrates 122 are arranged at predetermined intervals, and each flexible substrate 122 is provided with a driving IC 124 that generates the control signal. An insertion member 216 made of a material having a high thermal conductivity is inserted between each flexible substrate 122 and the base 112. Thereby, heat generated by the operation of the driving IC 124 is transmitted to the radiation conversion panel 116 side through the flexible substrate 122, the insertion member 216, and the base 112.

  As shown in FIG. 5, a plurality of flexible boards 126 are arranged at predetermined intervals on the side surface in the x1 direction of the radiation conversion panel 116 (photoelectric conversion layer 120 thereof), and a reading IC 128 is provided on each flexible board 126. Has been placed. An insertion member 218 made of a material having high thermal conductivity is interposed between each flexible substrate 126 and the base 112. As a result, heat generated by the operation of the reading IC 128 is transmitted to the radiation conversion panel 116 side through the flexible substrate 126, the insertion member 218 and the base 112.

  A power supply unit 94 is disposed on the back surface 129 of the base 112 (the surface on the bottom surface 46 side of the housing 29). An insertion member 220 made of a material having high thermal conductivity is inserted between the power supply unit 94 and the base 112. Thereby, the heat generated due to the operation of the power supply unit 94 is transmitted to the radiation conversion panel 116 side through the insertion member 220 and the base 112.

  A plurality of circuit boards 130 are attached around the power supply unit 94 on the back surface 129 of the base 112 so as to surround (avoid) the power supply unit 94. Each circuit board 130 is fixed via a plurality of bolts 131 in a state of being separated from the back surface 129 of the base 112 by a predetermined distance. An electronic component 132 is disposed on one surface (z1 direction side) of each circuit board 130. Between each circuit board 130 and the base 112, an insertion member 222 made of a material having high thermal conductivity is inserted. Thereby, heat generated by the operation of the electronic component 132 is transmitted to the radiation conversion panel 116 side through the circuit board 130, the insertion member 222, and the base 112.

  Here, the insertion members 216, 218, 220, and 222 enable a thermal short circuit between the heat generation source (the driving IC 124, the reading IC 128, the power supply unit 94, and the electronic component 132) and the radiation conversion panel 116. Functions as the second heat transfer means. The material of the insertion member 216 or the like is not limited as long as it is a substance having a high thermal conductivity, and may be, for example, copper, aluminum, graphite, a high thermal conductive resin, or the like. In order to prevent occurrence of a short circuit or malfunction between electronic components, a material that also has electrical insulation may be used as the insertion member 216 or the like.

  The heat source includes at least one of electronic components (driving IC 124, reading IC 128, and electronic component 132) for controlling the operation of the radiation conversion panel 116, and a power supply unit 94 that supplies power to the radiation conversion panel 116. included.

  As shown in FIG. 5, a flexible substrate 126 is connected to some circuit boards 130, while a flexible substrate 122 is connected to other circuit boards 130 as shown in FIG. 6.

  In order to prevent the power supply unit 94, the circuit board 130, and the electronic component 132 from being deteriorated due to the irradiation of the radiation 16, the base 112 may be made of a lead plate capable of shielding the radiation 16, or It may be configured to include lead.

  FIG. 9A is an enlarged cross-sectional view showing the internal structure of the radiation conversion panel 116 and the like, and shows a case where a CsI scintillation layer 118 is directly deposited on the photoelectric conversion layer 120.

  In this case, the photoelectric conversion layer 120 is formed on the vapor deposition substrate 230, such as a flexible plastic substrate bonded to the inner wall on the irradiation surface 36 side of the housing body 30 via the adhesive layer 212. A thin film transistor (TFT) layer 232 made of a-Si or the like, and a photoelectric conversion film 234 such as a photodiode or phototransistor made of a-Si or the like formed on the TFT layer 232 are formed.

  The CsI scintillation layer 118 is formed by forming CsI (Tl) (cesium iodide to which thallium is added) as a strip-like columnar crystal structure 236 on the photoelectric conversion film 234 by a vacuum deposition method. Note that the CsI (Tl) scintillation layer 118 is sealed with a light-transmitting moisture-proof protective material 238 made of polyparaxylylene resin because the columnar crystal structure 236 has a characteristic of being weak against humidity. Further, a metal reflection layer (first heat transfer means) 240 made of aluminum or the like is formed on the base 112 side of the moisture-proof protective material 238. The reflective layer 240 is used to reflect visible light to the photoelectric conversion film 234 side when visible light converted from the radiation 16 in the columnar crystal structure 236 travels to the base 112 side.

  Here, the reflective layer 240 having high thermal conductivity functions as first heat transfer means for transmitting heat generated from a heat source such as the electronic component 132 by surface contact with the radiation conversion panel 116.

  FIG. 9B is an enlarged cross-sectional view showing the internal structure of the radiation conversion panel 116 and the like, and shows a case where the photoelectric conversion layer 120 is formed on the scintillation layer 118 of CsI.

  In this case, the CsI scintillation layer 118 has a columnar crystal structure 236 formed on a vapor deposition substrate 242 having a high thermal conductivity by a vacuum vapor deposition method, and the columnar crystal structure 236 is sealed with a moisture-proof protective material 238. Further, on the irradiation surface 36 side of the moisture-proof protective material 238, a photoelectric conversion film 234 made of a-Si or the like bonded via an adhesive layer 244 and a TFT layer 232 made of a-Si or the like are sequentially formed. . The TFT layer 232 is bonded to the inner wall on the irradiation surface 36 side of the housing body 30 through the adhesive layer 212.

  Here, the vapor deposition substrate 242 functions as first heat transfer means for transmitting heat generated from the heat source by surface contact with the radiation conversion panel 116. The vapor deposition substrate 242 may be a substrate made of a resin having high thermal conductivity, or may be a substrate made of glass mixed with a material having high thermal conductivity. Further, in the case where the vapor deposition substrate 242 is made of a material such as a metal having low light transmittance, the vapor deposition substrate 242 has a structure in which visible light converted from the radiation 16 in the columnar crystal structure 236 travels to the insertion member 222 side. The visible light can be reflected to the photoelectric conversion film 234 side.

  Here, according to the characteristic of the photoelectric converting layer 120, the structure which accelerates | stimulates the transfer of the heat | fever to the photoelectric converting layer 120 side may be taken, and the structure insulated on the contrary may be taken. By suppressing the temperature rise on the photoelectric conversion layer 120 side, it is possible to reduce the influence on the radiation image due to the generation of dark current. In any case, it is preferable that the light transmittance is high and the absorption of the radiation 16 is small.

  For example, when heat transfer is promoted, a material having a relatively high thermal conductivity may be used for the adhesive layer 244 and / or the moisture-proof protective material 238. On the other hand, in the case of heat insulation, a material having a relatively low thermal conductivity may be used for the adhesive layer 244 and / or the moisture-proof protective material 238. As an adhesive having high thermal conductivity, there is a heat dissipation silicone adhesive {for example, Dow Corning TC-2030 (trade name, registered trademark) manufactured by Toray Industries, Inc.}. As the film adhesive, an adhesive in which carbon fibers having high thermal conductivity are arranged in the thickness direction in a thin epoxy resin film may be used.

  FIG. 10 is a block diagram of the electronic cassette 20A.

  The photoelectric conversion layer 120 includes, as a switching element, a photoelectric conversion element 140 such as a pin-type photodiode or a phototransistor that can store radiation 16 (see FIGS. 1, 2, 5, and 6) by converting it into charges. Thin film transistor (TFT) 142. Note that FIG. 10 illustrates the case where the photoelectric conversion element 140 is a pin-type photodiode.

  In this case, in the photoelectric conversion layer 120, a plurality of signal lines 144 and gate lines 146 are arranged on one surface of a substrate made of glass or resin so as to intersect with each other, and are partitioned by each gate line 146 and each signal line 144. By providing the photoelectric conversion elements 140 and the TFTs 142 in the small areas, the plurality of photoelectric conversion elements 140 and the plurality of TFTs 142 are arranged in a two-dimensional matrix on the substrate. Further, one bias line 148 is connected to one photoelectric conversion element 140, and each bias line 148 is connected to a bias power source 172 through one connection 150.

  Here, the anode electrode of the photoelectric conversion element 140 is connected to the bias line 148, and the cathode electrode is connected to the source electrode S of the TFT 142. On the other hand, the gate electrode G of the TFT 142 is connected to the gate drive circuit 152 via the gate line 146, and the drain electrode D is connected to the signal readout circuit 154 via the signal line 144. In this case, the gate driving circuit 152 is a driving circuit unit for driving the radiation conversion panel 116 corresponding to the plurality of driving ICs 124, while the signal reading circuit 154 is a radiation corresponding to the plurality of reading ICs 128. It is a readout circuit unit that reads out an electrical signal corresponding to an image.

  The bias power source 172 applies a bias voltage (reverse bias voltage) in the reverse direction to each photoelectric conversion element 140 via the connection 150 and each bias line 148. In FIG. 10, since the bias line 148 is connected to the p-layer side of the pin type photoelectric conversion element 140 via the anode electrode, the bias power source 172 connects the wiring 150 and the anode electrode of the photoelectric conversion element 140. A negative voltage (which may be a voltage lower than the cathode electrode by a predetermined voltage or more) is applied as a reverse bias voltage via the bias line 148. When the bias line 148 is connected to the cathode electrode by forming the pin type stacking order of the photoelectric conversion element 140 in reverse (the photoelectric conversion element 140 is formed so that the polarity of the photoelectric conversion element 140 is reversed), From 172, a positive voltage (which is higher than the anode electrode by a predetermined voltage or higher) may be applied as a reverse bias voltage to the cathode electrode. In that case, the direction of connection of the photoelectric conversion element 140 to the bias power source 172 in FIG. 10 is reversed.

  When a signal readout voltage (control signal) is applied from the gate drive circuit 152 to the gate electrode G of the TFT 142 via the gate line 146, the gate of the TFT 142 opens, and the charge accumulated in the photoelectric conversion element 140, that is, An electric signal (radiation image signal) is read from the drain electrode D to the signal line 144 via the source electrode S of the TFT 142.

  In the signal readout circuit 154, an amplifier 160, a sample hold circuit 162, a multiplexer 164, and an AD converter 166 are sequentially connected to each signal line 144. Therefore, the electric signal read out through each signal line 144 is amplified by the amplifier 160 formed of a charge amplifier, sampled by the sample hold circuit 162, and then sequentially supplied to the AD converter 166 through the multiplexer 164. , Converted into a digital signal (digital value). The AD converter 166 sequentially outputs the electrical signal of each photoelectric conversion element 140 converted into a digital value to a cassette control unit 174 described later.

  The electronic cassette 20A has a control unit 170 for controlling the entire apparatus.

  In addition to the power switch 54, the display 56, the input terminal 58, the USB terminal 60, the card slot 64, the indicator 66, the power supply unit 94, and the bias power supply 172, the control unit 170 includes the radiation conversion panel 116, the gate drive circuit 152, and the signal. A cassette control unit 174 that controls the readout circuit 154 and the like, and a communication unit 176 that transmits and receives signals to and from the console 22 by wireless communication.

  The power supply unit 94 includes a power supply circuit 178 and a power supply 180. The power source 180 is a power storage means such as a battery or a capacitor (for example, an electric double layer capacitor). The power supply circuit 178 is a power conversion circuit such as a DC / DC converter that can convert the voltage of the power supply 180 into a desired voltage and supply it to each part in the electronic cassette 20A.

  The cassette control unit 174 is a computer including a microcomputer, and realizes various functions by a CPU (not shown) reading and executing a program recorded in a ROM.

  Specifically, the cassette control unit 174 includes an image memory 182 and a storage unit 186. The image memory 182 stores a radiation image acquired from the radiation conversion panel 116 via the signal readout circuit 154. The storage unit 186 stores cassette ID information for specifying the electronic cassette 20A.

  In the control unit 170, the bias power source 172, the cassette control unit 174, and the communication unit 176 are realized by the electronic component 132 mounted on the circuit board 130 described above.

[Operation of Radiation Imaging Device According to First Embodiment]
Next, operation | movement of the radiation imaging system 10 containing the electronic cassette 20A which concerns on 1st Embodiment is demonstrated according to the flowchart of FIG. In the description of the operation, the description will be given with reference to FIGS.

  First, in step S1, the user carries the electronic cassette 20A from a predetermined storage location such as a radiology department in a hospital to the imaging table 12 (see FIG. 1). In this case, the electronic cassette 20A is in a sleep state in which the power supply unit 94 (see FIGS. 5, 6, and 10) supplies power only to the cassette control unit 174, and only the cassette control unit 174 is operating. .

  Next, the user turns on the power switch 54 after placing the electronic cassette 20 </ b> A on the imaging table 12 with the irradiation surface 36 facing upward. Thereby, first, the cassette control unit 174 controls the power supply unit 94 so as to supply power to the display 56, the indicator 66, and the communication unit 176 in addition to the cassette control unit 174. As a result, the display 56 displays the activation of the electronic cassette 20A on the screen. The indicator 66 emits light indicating activation of the electronic cassette 20A by an LED or the like. The user can grasp that the electronic cassette 20 </ b> A is activated by visually recognizing the screen display of the display 56 or the light emission of the indicator 66. Further, the communication unit 176 can transmit and receive signals wirelessly with the console 22.

  Next, the user operates the console 22 to include imaging conditions such as subject information related to the subject 14 to be imaged (for example, the tube voltage and tube current of the radiation source 18 and the exposure time of the radiation 16). Register a shooting order. Note that when the number of images to be imaged, the imaging region, and the imaging method are determined in advance, the user registers these conditions in the imaging order. As described above, since the wireless transmission / reception of signals is possible between the console 22 and the communication unit 176, the cassette control unit 174 transmits the imaging order to the console 22 by wireless communication via the communication unit 176. In response to the request, the console 22 transmits the imaging order to the electronic cassette 20A by wireless communication in response to a transmission request from the electronic cassette 20A. The imaging order received by the communication unit 176 is stored in the storage unit 186.

  In the next step S2, the user and the electronic cassette 20A prepare for photographing.

  In this case, the cassette control unit 174 controls the power supply unit 94 so as to supply power to each unit in the electronic cassette 20A other than the display 56, the indicator 66, the cassette control unit 174, and the communication unit 176. As a result, the bias power source 172 that receives power supply from the power supply unit 94 applies a reverse bias voltage to each photoelectric conversion element 140, and each photoelectric conversion element 140 reaches a state where charges can be accumulated. The cassette control unit 174 controls the gate drive circuit 152 to turn off all the TFTs 142.

  On the other hand, the user adjusts the distance between the radiation source 18 and the radiation conversion panel 116 to the SID (distance between the source image reception images), arranges the subject 14 on the irradiation surface 36, and captures the imaging region of the subject 14. Is positioned so that the center position of the imaging region substantially coincides with the center position of the imageable area 40.

  In step S3 after the preparation for imaging is completed in this way, the user turns on an exposure switch (not shown) provided in the console 22 or the radiation source 18. When the console 22 is provided with an exposure switch, the imaging conditions are transmitted from the console 22 to the radiation source 18 by wireless communication after the exposure switch is turned on. If the radiation source 18 is equipped with an exposure switch, after the exposure switch is turned on, transmission of imaging conditions is requested from the radiation source 18 to the console 22 by wireless communication. In response to a transmission request from the source 18, the imaging condition is transmitted to the radiation source 18 by wireless communication.

  In the next step S4, when receiving the imaging condition, the radiation source 18 irradiates the subject 14 with the radiation 16 having a predetermined dose according to the imaging condition for a predetermined exposure time. The radiation 16 passes through the subject 14 and reaches the radiation conversion panel 116 in the housing body 30. In this case, the scintillation layer 118 emits visible light having an intensity corresponding to the intensity of the radiation 16, and each photoelectric conversion element 140 constituting the photoelectric conversion layer 120 converts the visible light into an electric signal and accumulates it as an electric charge. .

  At this time, the sensitivity distribution in the surface of the radiation conversion panel 116 is substantially uniform due to the heating effect using heat radiation from the heat radiation source of the electronic cassette 20A.

  In the next step S <b> 5, the cassette control unit 174 controls the gate drive circuit 152 to apply a signal read voltage (control signal) from the gate drive circuit 152 to one gate line 146. As a result, the gates of all TFTs 142 to which the gate electrode G is connected to the gate line 146 are opened, and the charges accumulated in the respective photoelectric conversion elements 140 to which these TFTs 142 are connected (the pin type photoelectric photoelectric conversion in FIG. 10). In the conversion element 140, electrons) are read out to the signal lines 144 as electric signals. Each amplifier 160 amplifies the read electrical signal, and each sample and hold circuit 162 samples the amplified electrical signal and sequentially supplies it to the AD converter 166 via the multiplexer 164. The AD converter 166 performs AD conversion on the sequentially supplied electric signals and converts them into digital signals.

  In the next step S <b> 6, the radiation image corresponding to the electrical signal converted into the digital signal is temporarily stored in the image memory 182 of the cassette control unit 174.

  In this way, after the readout of the electrical signal (the corresponding radiation image) for each photoelectric conversion element 140 connected to one gate line 146 is completed, the cassette control unit 174 controls the gate drive circuit 152. Then, the gate lines 146 to which a signal reading voltage is applied are sequentially switched, and electrical signals are sequentially read out from the photoelectric conversion elements 140 connected to the switched gate lines 146. Therefore, in the electronic cassette 20A, the processes in steps S5 and S6 are repeated until the reading of the radiation image from each photoelectric conversion element 140 connected to all the gate lines 146 is completed.

  In this manner, the cassette control unit 174 stores the radiographic images from all the photoelectric conversion elements 140 in the image memory 182 in step S7 after the radiographic images of the subject 14 are stored in the image memory 182. The stored radiographic image is displayed on the display 56, and the radiographic image and the cassette ID information stored in the storage unit 186 are both transmitted to the console 22 via the communication unit 176 by wireless communication. The console 22 performs predetermined image processing on the received radiographic image, and transmits the radiographic image after the image processing to the display device 24 by wireless communication. The display device 24 displays the received radiation image. Therefore, the user visually recognizes the radiographic image displayed on the display 56 or the radiographic image displayed on the display device 24 to determine whether the subject 14 has been appropriately imaged according to the imaging order. Can be easily determined.

  In step S8, when imaging of the subject 14 is completed (step S8: YES), the user releases the subject 14 to end imaging (step S9), and then presses the power switch 54 to set the electronic cassette. 20A is shifted to the sleep state. Thereafter, the user carries the electronic cassette 20A to a predetermined storage location (step S10).

  On the other hand, when a plurality of images are captured with respect to the subject 14 and all the imaging is not completed (step S8: NO), the process returns to step S2 or step S3, and the next imaging or Preparation for shooting for the next imaging is performed.

[Effects of the radiation imaging apparatus according to the first embodiment]
As described above, since the heat generation source of the electronic cassette 20A and the radiation conversion panel 116 are thermally coupled, the heat generated by the operation of the apparatus can be used, and a separate heating apparatus is unnecessary. It becomes. Further, since the heat generation from the heat generation source is transmitted by surface contact with the radiation conversion panel 116, the temperature distribution of the radiation conversion panel 116 becomes substantially uniform and the sensitivity distribution of the radiation conversion panel 116 becomes substantially uniform. . Thereby, it is possible to suppress the occurrence of image unevenness due to heat generation inside the housing 29 without increasing the weight of the entire apparatus.

  The heat generation source includes electronic components (driving IC 124, reading IC 128, and electronic component 132) used for operation control of the radiation conversion panel 116, and a power supply unit 94 that supplies power to the radiation conversion panel 116. At least one of them may be included. Thereby, during normal operation of the apparatus, heat is received from the electronic component or the power supply unit 94 that generates a particularly large amount of heat, which is efficient.

  Furthermore, you may further have the 2nd heat transfer means which enables the thermal short circuit between the said heat generation source and the radiation conversion panel 116. FIG. Thereby, heat can be more efficiently transferred.

  Further, the second heat transfer means may be insertion members 216, 218, 220, and 222 inserted between the heat generation source and the radiation conversion panel 116. Thereby, heat can be transmitted to the radiation conversion panel 116 with a simple configuration.

  Furthermore, the radiation conversion panel 116 includes a scintillation layer 118 that converts the radiation 16 into electromagnetic waves of other wavelengths, and a photoelectric conversion layer 120 that converts the electromagnetic waves converted by the scintillation layer 118 into a radiation image. The panel 116 may be disposed in the order of the photoelectric conversion layer 120 and the scintillation layer 118 with respect to the irradiation side of the radiation 16.

  Further, the scintillation layer 118 may include vapor deposition substrates 233 and 242 and columnar crystal structures 236 formed on the vapor deposition substrates 233 and 242.

  Further, the columnar crystal structure 236 may be CsI. Thereby, a radiographic image can be acquired in the state where the electric charge captured by the deep trap of the photoelectric layer is discharged.

  Furthermore, the first heat transfer means is preferably a vapor deposition substrate 242. Thereby, it can implement | achieve, without providing a different member, and the efficiency of heat transfer improves.

  Further, the first heat transfer means may transmit heat generated from the heat source by contacting the radiation conversion panel 116 on the surface opposite to the irradiation side of the radiation 16. Thereby, heat can be directly transferred to the scintillation layer 118.

  Furthermore, the photoelectric conversion layer 120 is preferably composed of an a-Si photoelectric conversion element 140. Thereby, for the reason described above, a radiographic image can be acquired under a state in which charges captured by a shallow trap in the photoelectric layer are discharged.

  Further, by making the temperature distribution of the radiation conversion panel 116 substantially uniform, the generation distribution of traps caused by the a-Si photoelectric conversion element 140 becomes substantially uniform. When a mechanism for realizing a so-called optical reset method is incorporated in the electronic cassette 20A, the irradiation amount of the reset light to the photoelectric conversion layer 120 can be reduced. In other words, a local temperature rise can be suppressed by making the temperature distribution of the radiation conversion panel 116 substantially uniform, and traps that are normally formed in the photoelectric conversion layer 120 due to light emission of the scintillation layer 118 are less likely to be formed. Therefore, it is not necessary to excessively increase the irradiation amount of the reset light, and can be kept to a minimum. In particular, it is more effective because the temperature of the radiation conversion panel 116 tends to be higher during moving image shooting.

  The optical reset method described above is a method described in Japanese Patent Application Publication No. 2010-525359, Japanese Patent Application Laid-Open No. 2007-225598, Japanese Patent Application No. 2010-258184, and the like. Specifically, when the radiation 16 is not irradiated (non-imaging), the photoelectric conversion element 140 is irradiated with reset light so that charges are pre-filled in the impurity level, and then, when the radiation 16 is irradiated (imaging). In other words, the amount of dark current that is a cause of electrical noise is reduced by preventing the charge level converted from visible light from being captured by the impurity level.

[Description of Radiation Imaging Device According to Modification of First Embodiment]
Next, modified examples (first to fourth modified examples) of the electronic cassette 20A according to the first embodiment will be described with reference to FIGS. In the modification, the same reference numerals are given to the same components as those of the present embodiment, and detailed description thereof will be omitted.

  In the first modification, the method of supplying heat from the heat source of the electronic cassette 20Aa is different from that of the first embodiment (electronic cassette 20A in FIG. 5).

  As illustrated in FIG. 12, a sheet-like heat insulating member 250 is attached to the inner wall 208 of the housing 29 (the inner wall of the bottom surface 46 of the housing body 30) over substantially the entire surface. Further, a sheet-like heat insulating member 254 is attached to the inner wall 252 of the housing 29 (the inner wall of the lid member 32) over substantially the entire surface. Furthermore, a sheet-like heat insulating member (heat insulating means) 258 is attached to the inner wall 256 of the housing 29 (inner wall of the lid member 34) over substantially the entire surface. In this way, by blocking heat dissipation to the outside of the housing 29, more heat generation inside the housing 29 can be used, which is more efficient. In particular, by providing the heat insulating member 250 (or 254, 258) on the inner wall 208 (or 252, 256) of the housing 29, heat can be transferred to the radiation conversion panel 116 with a simple configuration.

  In addition, the heat insulation means of the housing | casing 29 is not limited to this method, You may take a various method. In the example of FIG. 12, the insertion members 218, 220, and 222 (see FIG. 5) are omitted. By arranging these insertion members 218 and the like together with the heat insulating member 250 and the like, the utilization efficiency of heat generation is further improved.

  In the second modification, the configuration of the radiation conversion panel 260 (scintillation layer 261) is different from that of the first embodiment (the radiation panel 116 in FIG. 9B).

  As shown in FIG. 13, the scintillation layer 261 is composed of a vapor deposition substrate 242, a columnar crystal structure 236, and a moisture-proof protective material 238, as well as a highly thermally conductive flat plate member (first member) attached to the base 112 side of the vapor deposition substrate 242. Heat transfer means) 262. That is, the flat plate member 262 is configured to be in surface contact with one surface (surface on the base 112 side) of the radiation conversion panel 260 (scintillation layer 261). Thereby, heat can be transmitted to the radiation conversion panel 116 substantially uniformly with a simple configuration. In the case where the thermal conductivity of the vapor deposition substrate 242 is not so high, it is particularly effective because it assists heat transfer.

  In the third modified example, the insertion member 278 interposed between the heat generation source and the radiation conversion panel 116 may be detachably moved.

  As shown in FIGS. 14A and 14B, an actuator (moving means) 270 made of a cylinder or the like is disposed on the right side (x1 direction) of the base 112 and the circuit board 130. The substantially cylindrical main body 272 accommodates a rod 274 configured to advance and retract in the x direction. A cubic insertion member 278 is fixed to the tip 276 of the rod 274.

  For example, in the state shown in FIG. 14A, when the rod 274 is advanced in the x2 direction and displaced by a predetermined amount or more in accordance with an instruction from the cassette control unit 174, the insertion is performed between the base 112 and the circuit board 130. A member 278 is inserted (see FIG. 14B). On the other hand, in the state shown in FIG. 14B, when the rod 274 is retracted in the x1 direction and displaced by a predetermined amount or more in accordance with an instruction from the cassette control unit 174, the insertion member 278 causes the base 112 and the circuit board 130 to move. It is removed away from (see FIG. 14A).

  As described above, since the moving means (actuator 270) for detachably moving the insertion member 278 is provided, the timing for supplying heat to the radiation conversion panel 116 can be controlled. In particular, the sensitivity characteristic of the radiation conversion panel 116 can be stabilized by inserting the insertion member 278 within at least the imaging time of the radiation 16.

  The means for moving the insertion member 278 is not limited to this, and various methods may be used. Moreover, even if it comprises so that the insertion member 278 can be inserted by moving another site | part, fixing the insertion member 278, the same effect is obtained.

  In the fourth modification, a temperature sensor is arranged for each part of the electronic cassette 20A whose response characteristics change depending on the temperature, and feedforward control and / or feedback control is performed based on the detected value. May be. As the temperature sensor, various types of sensors including a thermocouple, a thermistor, and the like may be used. For example, a platinum thin film temperature sensor made of an ultra-compact resistance temperature detector in which platinum is deposited on a ceramic plate may be used. Further, the part where the temperature sensor is arranged may be not only the scintillation layer 118 and the photoelectric conversion layer 120 but also a part in the vicinity thereof (for example, the base 112, the inner wall of the housing 29, etc.).

[Description of Radiation Imaging Device According to Second Embodiment]
Next, an electronic cassette 20B according to the second embodiment will be described with reference to FIGS.

  In the electronic cassette 20B according to the second embodiment, the x2 direction side of the housing 29 is a thin plate-like lid member 32, and the x1 direction side is a gripping part 300 that can be gripped by the user. Therefore, the user can carry the electronic cassette 20B while holding the handle 302 of the holding unit 300. Further, as shown in FIG. 16, by rotating the lid member 32 around a hinge member (not shown), the opening portion 44a can be closed by the lid member 32, while the opening portion 44a is opened. You can also.

  Of course, the second embodiment configured as described above can achieve the same effects as those of the first embodiment. Further, in the second embodiment, since the electronic cassette 20B is transported by gripping the handle 302 with the lid member 32 down, even if the housing 29 is dropped during transportation, only the lid member 32 is damaged. I can finish it.

[Description of Radiation Imaging Device According to Third Embodiment]
Next, an electronic cassette 20C according to the third embodiment will be described with reference to FIGS.

  In the electronic cassette 20C according to the third embodiment, the thickness of the housing 29 is entirely thin, the side surface 42a of the housing body 30 is a curved surface, and the lid member 32 is also curved in accordance with the curved surface. It has become. In this case, the central portion of the side surface 42a is recessed toward the x1 direction, and the central portion of the lid member 32 is a convex portion that bulges in the x1 direction corresponding to the concave portion of the side surface 42a. A handle 304 is provided on the convex portion.

  On the other hand, two corner portions 306 (two corner portions connecting the side surface 42b and the side surfaces 42c and 42d) in the x1 direction of the housing body 30 are recessed toward the center of the housing body 30, and the recessed portion includes An L-shaped buffer member 308 is fitted.

  In addition, since the housing 29 of the electronic cassette 20C is thin, the display 56 is disposed outside the imageable area 40 on the irradiation surface 36, and the power switch 54, the input terminal 58, the USB terminal 60, and the card slot 64 are It is arranged on the side surface 42d.

  Also in the electronic cassette 20C according to the third embodiment configured as described above, the same effects as those of the first and second embodiments can be obtained. In the third embodiment, since the handle 304 is provided on the lid member 32, the electronic cassette 20C is transported by gripping the handle 304 with the lid member 32 facing upward. The electronic cassette 20C can be easily transported.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change freely in the range which does not deviate from the main point of this invention.

DESCRIPTION OF SYMBOLS 10 ... Radiation imaging system 16 ... Radiation 20A, 20Aa, 20B, 20C ... Electronic cassette 29 ... Housing 30 ... Housing main body 32, 34 ... Lid member 94 ... Power supply part 110 ... Chamber 116, 260 ... Radiation conversion panels 118, 261 ... Scintillation layer 120 ... Photoelectric conversion layer 124 ... Drive IC 128 ... Read IC
DESCRIPTION OF SYMBOLS 130 ... Circuit board 132 ... Electronic component 216, 218, 220, 222, 278 ... Insertion member 230, 242 ... Deposition board 236 ... Columnar crystal structure 250, 254, 258 ... Thermal insulation member 262 ... Flat plate member 270 ... Actuator

Claims (15)

A radiation imaging apparatus including a radiation conversion panel that converts radiation into a radiation image,
A first heat transfer unit that thermally couples a heat generation source of the radiation imaging apparatus and the radiation conversion panel and transmits heat generated from the heat generation source by surface contact with the radiation conversion panel is provided. Radiation imaging device. The radiation imaging apparatus according to claim 1.
The radiation imaging apparatus according to claim 1, wherein the heat source includes at least one of an electronic component used for operation control of the radiation conversion panel and a power supply unit that supplies power to the radiation conversion panel. The radiation imaging apparatus according to claim 2, wherein
The radiation imaging apparatus according to claim 1, wherein the first heat transfer means is a flat member in surface contact with one surface of the radiation conversion panel. The radiation imaging apparatus according to any one of claims 1 to 3,
The radiation imaging apparatus further comprising a second heat transfer means that enables a thermal short circuit between the heat generation source and the radiation conversion panel. The radiation imaging apparatus according to claim 4.
The radiation imaging apparatus according to claim 2, wherein the second heat transfer means is an insertion member interposed between the heat generation source and the radiation conversion panel. The radiation imaging apparatus according to claim 5, wherein
A radiation imaging apparatus further comprising moving means for detachably moving the insertion member. The radiation imaging apparatus according to claim 6.
The radiographic imaging apparatus, wherein the moving means interposes the insertion member at least within an imaging time by the radiation. The radiation imaging apparatus according to any one of claims 1 to 7,
The radiation conversion panel is composed of a scintillation layer that converts the radiation into electromagnetic waves of other wavelengths, and a photoelectric conversion layer that converts the electromagnetic waves converted by the scintillation layer into the radiation image.
The radiation imaging apparatus, wherein the radiation conversion panel is arranged in the order of the photoelectric conversion layer and the scintillation layer with respect to the radiation irradiation side. The radiation imaging apparatus according to claim 8.
The scintillation layer includes a substrate and a scintillator crystal formed on the substrate. The radiation imaging apparatus according to claim 9.
The scintillator crystal is made of CsI. The radiation imaging apparatus according to claim 9 or 10,
The radiation imaging apparatus, wherein the first heat transfer means is the substrate. The radiation imaging apparatus according to any one of claims 8 to 11,
The first heat transfer means transmits heat generated from the heat generation source by contacting the radiation conversion panel with a surface opposite to the radiation irradiation side. The radiation imaging apparatus according to any one of claims 1 to 12,
The said photoelectric conversion layer is comprised with the photoelectric conversion element of a-Si, The radiation imaging device characterized by the above-mentioned. The radiation imaging apparatus according to any one of claims 1 to 13,
The radiation imaging apparatus further comprising a heat insulating means for blocking heat radiation to the outside of the housing. The radiation imaging apparatus according to claim 14.
The radiation imaging apparatus, wherein the heat insulating means is a heat insulating member provided on an inner wall of the housing.

Images