WO2013046915A1

WO2013046915A1 - Radiographic imaging unit

Info

Publication number: WO2013046915A1
Application number: PCT/JP2012/069605
Authority: WO
Inventors: 西納直行; 岩切直人; 中津川晴康; 大田恭義; 北野浩一
Original assignee: 富士フイルム株式会社
Priority date: 2011-09-30
Filing date: 2012-08-01
Publication date: 2013-04-04

Abstract

A radiographic imaging unit (10) is configured by laminating a direct conversion-type first radiation conversion layer (28a) and an indirect conversion-type second radiation conversion layer (28c). A first radiation detection section (72a) in the first radiation conversion layer (28a) converts fluorescent light (102) into electric charge (94c, 96c), when said fluorescent light (102) converted from radiation (16) in a second radiation detection section (72c) of the second radiation conversion layer (28c) has been incident. A first electric charge detection section (70a) in the first radiation conversion layer (28a) can extract the electric charge (94c, 96c) converted from said fluorescent light (102).

Description

Radiography equipment

The present invention relates to a radiation imaging apparatus in which two radiation conversion layers are laminated along the incident direction of radiation.

JP-A 2000-338297 and JP-A 2010-56397 disclose a radiographic apparatus including a radiation conversion layer containing a substance capable of detecting radiation.

Japanese Patent Laid-Open No. 2000-338297 discloses an image reading unit including a photoconductive layer made of amorphous selenium (a-Se) and an image recording unit including a stimulable phosphor layer in order with respect to the incident direction of radiation. A stacked radiographic apparatus is disclosed. In this apparatus, first, image recording is performed by irradiating the stimulable phosphor layer with radiation via an image reading unit. Next, the stimulable phosphor layer is irradiated with excitation light having a wavelength in the vicinity of 600 nm through the image reading unit while applying a voltage (electric field) that causes an avalanche action to the photoconductive layer. Thereby, the stimulable phosphor layer generates stimulated emission light having a wavelength near 400 nm, and the photoconductive layer converts the incident stimulated emission light into electric charge. The electric charge is amplified by an avalanche action and then output as an image signal.

In JP 2010-56397 A, a first radiation conversion layer including an a-Se semiconductor layer and a second radiation conversion layer including a scintillator and a sensor unit are sequentially stacked in the radiation incident direction. A radiation imaging apparatus is disclosed. In this apparatus, the semiconductor layer directly converts a low energy component of radiation (energy component of radiation according to the low voltage when the tube voltage of the radiation source that irradiates the radiation is low) into electric charge. In the second radiation conversion layer, the scintillator converts a high energy component of radiation (energy component of radiation according to a high tube voltage) into fluorescence, and the sensor unit converts the fluorescence into electric charge.

By the way, a direct conversion radiation conversion layer including an a-Se semiconductor layer can generate a high-quality radiation image as compared with an indirect conversion radiation conversion layer including a scintillator. However, the a-Se semiconductor layer is less likely to absorb high-energy components of radiation than a scintillator. That is, as shown in FIG. 22, the K edge of a-Se exists on the lower energy side than the K edge of GOS (Gd ₂ O ₂ S), CsI, or Ba (for example, BaFBr, BaFCl) used in the scintillator. To do. Therefore, a-Se easily absorbs low energy components of radiation, but hardly absorbs high energy components. On the other hand, a GOS, CsI, or Ba scintillator can easily absorb a high-energy component of radiation, but hardly absorbs a low-energy component, as compared with an a-Se semiconductor layer.

Therefore, for example, when radiography is performed on a mammo using a direct conversion type radiation conversion layer, as shown in FIG. 23, if the thickness of the semiconductor layer of a-Se is about 200 μm to 300 μm, 90% or more. The radiation absorption rate of can be obtained. Therefore, in radiography for mammons, soft tissues, or tumors that easily absorb low-energy components of radiation, high-quality radiation images (images corresponding to the low-energy components) are acquired using a direct conversion type radiation conversion layer. be able to.

On the other hand, when so-called general imaging such as radiography of the chest and abdomen is performed using the direct conversion type radiation conversion layer, as shown in FIG. 24, even if the thickness of the semiconductor layer of a-Se is 1000 μm. The semiconductor layer does not reach a radiation absorption rate of 90% or more because its absorption is small with respect to a high energy component of radiation. Therefore, in order to realize a high radiation absorption rate of 90% or more with respect to a high energy component of radiation, the semiconductor layer needs to be a thick film of 1000 μm or more. However, when a thick semiconductor layer is deposited on a substrate, large protrusions are generated on the surface of the semiconductor layer after deposition due to dust on the substrate or bumping that occurs during deposition. As a result, the protrusions cause image defects, and the yield of the radiographic apparatus including the radiation conversion layer may be reduced.

FIG. 24 also shows the relationship between the radiation absorption rate and the film thickness of CsI or GOS used in the scintillator for comparison with a-Se. In the case of a scintillator including an element with a large atomic number, such as a scintillator made of CsI or GOS, the radiation absorption is relatively equivalent to that of a 1000 μm thick a-Se semiconductor layer with a relatively thin film thickness of about 300 μm to 500 μm. Rate is obtained. For this reason, conventionally, in radiography of the subject's chest, abdomen, or bone, these radiation images are acquired using an indirect conversion type radiation conversion layer.

FIG. 23 shows the thickness of the a-Se semiconductor layer when the radiation source for irradiating the mammo is set to the following conditions including the standard radiation quality defined by IEC (International Electrotechnical Commission) 61267. The relationship between (film thickness) and radiation absorption rate was examined.

“RQA-M1” is a result of the standard quality of RQA-M1 obtained when the tube voltage of the radiation source is 25 kV and the thickness of the Al addition filter used in the radiation source is 2 mm. “RQA-M2” is the standard quality of RQA-M2, and is the result obtained when the tube voltage is 28 kV and the thickness of the Al-added filter is 2 mm. “RQA-M3” is a standard quality of RQA-M3, and is a result obtained when the tube voltage is 30 kV and the thickness of the Al-added filter is 2 mm. “RQA-M4” is the standard quality of RQA-M4, and is the result obtained when the tube voltage is 35 kV and the thickness of the Al-added filter is 2 mm.

“Mo / Rh” is a result obtained when the target of the radiation source is Mo, the filter is Rh, the tube voltage of the radiation source is 28 kV, the thickness of the Rh filter is 25 μm, and the thickness of the Al-added filter is 2 mm. “Rh / Rh” is a result obtained when the target and the filter are both Rh, the tube voltage is 28 kV, the thickness of the Rh filter is 25 μm, and the thickness of the Al-added filter is 2 mm. “W / Rh” is a result obtained when the target is W, the filter is Rh, the tube voltage is 28 kV, the thickness of the Rh filter is 50 μm, and the thickness of the Al-added filter is 2 mm. “W / Al” is a result obtained when the target is W, the filter is Al, the tube voltage is 28 kV, the thickness of the Al filter is 500 μm, and the thickness of the Al-added filter is 2 mm.

On the other hand, FIG. 24 shows the relationship between the film thickness of the a-Se semiconductor layer and the radiation absorption rate when the radiation source used for general imaging is set to the following conditions including the standard radiation quality defined in IEC61267. The relationship was examined.

Here, “Se RQA3”, “CsI RQA3” and “GOS RQA3” are the standard quality of RQA3 for the a-Se semiconductor layer, the CsI scintillator and the GOS scintillator, respectively. This is a result obtained when the voltage is 50 kV and the thickness of the Al-added filter used for the radiation source is 10 mm.

“Se RQA5”, “CsI RQA5” and “GOS RQA5” are standard quality of RQA5 for the a-Se semiconductor layer, CsI scintillator and GOS scintillator, respectively, with tube voltage of 70 kV and Al added This is a result obtained when the thickness of the filter is 21 mm.

“Se RQA7”, “CsI RQA7” and “GOS RQA7” are standard quality of RQA7 for the a-Se semiconductor layer, CsI scintillator and GOS scintillator, respectively, with tube voltage of 90 kV and Al added This is a result obtained when the thickness of the filter is 30 mm.

“Se RQA9”, “CsI RQA9” and “GOS RQA9” are the standard quality of RQA9 for the a-Se semiconductor layer, CsI scintillator and GOS scintillator, respectively, and the tube voltage is 120 kV and Al is added. This is a result obtained when the thickness of the filter is 40 mm.

As described above, in order to obtain a direct conversion type radiation conversion layer that can be used for general imaging for the purpose of obtaining a high-quality radiation image, the thickness of the a-Se semiconductor layer constituting the radiation conversion layer is as follows. Becomes a thick film of 1000 μm (1 mm) or more. As a result, the deterioration of the image quality and the yield of the radiographic image are incurred.

The present invention has been made to solve the above-described problems. By realizing a direct conversion type radiation conversion layer that can be used for general imaging while avoiding thickening, high-quality radiation is achieved. An object of the present invention is to provide a radiation imaging apparatus capable of achieving image acquisition and yield improvement.

In order to achieve the above object, a radiation imaging apparatus according to the present invention is a radiation imaging apparatus in which two radiation conversion layers are stacked along the incident direction of radiation.
One radiation conversion layer has a first radiation detection unit that directly converts the radiation into an electric charge and a first charge detection unit that extracts the electric charge from the first radiation detection unit. The other radiation conversion layer is an indirect conversion type second radiation having a second radiation detection unit that converts the radiation into fluorescence and a second charge detection unit that converts the fluorescence into electric charge. Conversion layer,
The first radiation detection unit is characterized in that, when the fluorescence converted from the radiation by the second radiation detection unit is incident, the fluorescence can be converted into an electric charge.

According to this configuration, in the radiation imaging apparatus in which the first radiation conversion layer of the direct conversion type and the second radiation conversion layer of the indirect conversion type are stacked, the above-mentioned generated in the second radiation detection unit The fluorescence is incident on the first radiation conversion layer and the second charge detection unit. In this case, in the first radiation detection unit, the radiation is directly converted into electric charges, and the incident fluorescence is also converted into electric charges. Therefore, in the first radiation conversion layer, in addition to the charge directly converted from the radiation, the charge converted from the fluorescence is also used for forming a radiation image in the first radiation conversion layer.

Thereby, in this invention, without increasing the thickness of the first radiation detection part constituting the first radiation conversion layer, the sensitivity of the first radiation detection part is increased and the first radiation conversion layer is increased. This makes it possible to acquire a high-quality radiation image. Therefore, in the present invention, it is possible to realize a radiation imaging apparatus including a direct conversion type radiation conversion layer that can be used for general imaging such as radiography for the chest and abdomen. In addition, since it is not necessary to increase the thickness of the first radiation detection unit, it is possible to improve the yield of the radiation imaging apparatus including the first radiation conversion layer.

Here, in the radiation imaging apparatus, the first radiation conversion layer and the second radiation conversion layer are sequentially laminated in the radiation incident direction. In this case, it is preferable that the first radiation detection unit includes a semiconductor layer that directly converts the radiation into electric charges, and the second radiation detection unit is a scintillator that converts the radiation into the fluorescence. .

Thereby, in the first radiation conversion layer, the semiconductor layer constituting the first radiation detection unit absorbs the low energy component of the radiation and directly converts it into electric charges. On the other hand, in the second radiation conversion layer, the scintillator constituting the second radiation detection unit absorbs the high energy component of the radiation and converts it into fluorescence. In this case, since a part of the fluorescence corresponding to the high energy component is incident on the first radiation conversion layer, the semiconductor layer also converts a part of the fluorescence into an electric charge.

Thus, in the radiographic apparatus, a so-called hybrid configuration of the semiconductor layer and the scintillator can be employed to efficiently convert low energy components and high energy components of the radiation into electric charges. As a result, in the first radiation conversion layer, it is possible to form a radiation image including a high energy component in addition to the low energy component of the radiation.

Therefore, the first radiation conversion layer easily realizes high image quality of radiographic images for general imaging such as radiography of the chest and abdomen, and low-energy component radiographic images for mammo, soft tissue, or tumor. In addition, it is possible to avoid increasing the thickness of the semiconductor layer.

In the second radiation conversion layer, a radiation image including the high energy component can be formed. Therefore, in the second radiation conversion layer, it is possible to form a radiation image for general imaging and a radiation image for a bone part.

If the semiconductor layer is selenium, more preferably amorphous selenium (a-Se), but the scintillator absorbs more high-energy components of the radiation than the selenium, the above effect can be easily obtained. be able to.

The selenium can mainly convert light in the blue wavelength region into electric charge. Therefore, if the scintillator is a phosphor that generates fluorescence in at least the blue wavelength region, the fluorescence in the blue wavelength region is charged in the semiconductor layer by causing the fluorescence in the blue wavelength region to enter the semiconductor layer of selenium. Can be efficiently photoelectrically converted.

In order to obtain such an effect, the scintillator is preferably made of CsI: Na, CaWO ₄ , YTaO ₄ : Nb, BaFX: Eu (X is Br or Cl), or LaOBr: Tm. In particular, CsI: Na generates fluorescence in a wide wavelength region including light in a blue wavelength region and light having a longer wavelength than the blue wavelength region (for example, a long wavelength region of 500 nm or longer). Therefore, when a scintillator made of CsI: Na is used, the fluorescence in the blue wavelength region is photoelectrically converted into charges in the a-Se semiconductor layer, and the fluorescence in the long wavelength region is photoelectrically converted into charges in the second charge detection unit. It can be converted. As a result, photoelectric conversion in the first radiation conversion layer and the second radiation conversion layer can be efficiently performed, and each radiation acquired in the first radiation conversion layer and the second radiation conversion layer. High image quality can be easily realized.

The scintillator generates a first fluorescent material that generates fluorescence in a wavelength region that can be converted into charges in the semiconductor layer, and a first fluorescent material that generates fluorescence in a wavelength region that can be converted into charges in the second charge detection unit. And two fluorescent materials. In this case, in the second radiation conversion layer of the indirect conversion type, the first fluorescent material that is not normally used is actively used for the scintillator. For this reason, fluorescence generated in the first fluorescent material (for example, fluorescence in the blue wavelength region) is incident on the semiconductor layer to be converted into electric charges, and fluorescence generated in the second fluorescent material (for example, long wavelength) The fluorescence in the region) can be converted into charges by the second charge detection unit.

Thus, by configuring the scintillator by selecting the first fluorescent substance and the second fluorescent substance according to the characteristics of the semiconductor layer and the second charge detection unit, the first scintillator is configured. A desired radiation image can be acquired in the radiation conversion layer and the second radiation conversion layer. For example, in the first radiation conversion layer, a radiation image corresponding to a low energy component and a medium energy component of the radiation or a radiation image corresponding to a wide range of energy components from a low energy component to a high energy component is acquired. For this purpose, by selecting the first fluorescent material, the energy component absorbed in the semiconductor layer can be controlled to obtain a desired radiation image.

In the above description, the case where the semiconductor layer is selenium has been described, but instead of selenium, silicon (Si), more specifically, amorphous silicon (a-Si) or crystalline silicon (c-Si) is used. Alternatively, the semiconductor layer may be used. a-Si and c-Si have lower K-edges (Se: 12.7 keV, a-Si: 1.7 keV, c-Si: 1.1 keV) than the materials and selenium constituting the scintillator, and lower energy components Easy to absorb. Therefore, a radiation imaging apparatus using a semiconductor layer made of a-Si or c-Si is suitable for mammography.

In addition, since selenium can convert light in the blue wavelength region into electric charges, a scintillator made of a phosphor that generates fluorescence in the blue wavelength region must be selected as the scintillator combined with the selenium semiconductor layer. Absent. That is, scintillator options are limited.

On the other hand, in the a-Si or c-Si semiconductor layer, the entire visible light region is the sensitivity wavelength region, so any scintillator using a phosphor that generates fluorescence in the visible light region can be used. Even a scintillator can be selected as a scintillator that can be combined with an a-Si or c-Si semiconductor layer. Thereby, the choice of a scintillator can be increased.

Furthermore, a semiconductor layer made of CdTe having a K edge of 30 keV may be used. As shown in FIG. 22, any material constituting the scintillator has a higher K edge than CdTe (for example, CsI: 35 keV). The band gap of CdTe is 1.44 eV and has sensitivity in the visible light region. Therefore, similarly to the a-Si or c-Si semiconductor layer, a phosphor that emits fluorescence in the visible light region can be selected as the scintillator. Accordingly, even in this case, the number of scintillator options can be increased.

In addition, the first radiation detection unit is formed on the other surface of the semiconductor layer, a plurality of pixel electrodes formed on one surface of the semiconductor layer along the incident direction of the radiation, and the other surface of the semiconductor layer. And a common electrode. In this case, by applying a voltage between each pixel electrode and the common electrode, the charge generated in the semiconductor layer may be taken out by the first charge detection unit via each pixel electrode. .

Thus, if the thickness of the semiconductor layer is thin, an electric field generated in the semiconductor layer increases when a voltage is applied between the pixel electrodes and the common electrode. As a result, the charges in the semiconductor layer are amplified by the avalanche effect, and the number of charges taken out by the first charge detection unit via each pixel electrode increases. As described above, by reducing the thickness of the semiconductor layer, the sensitivity of the first charge detector is increased, and a high-quality radiation image can be easily acquired.

In addition, when the first radiation detection unit and the first charge detection unit are stacked along the incident direction of the radiation, each pixel electrode includes the first charge detection unit in the semiconductor layer. Preferably, the common electrode is formed on the opposite side of the semiconductor layer from the first charge detection unit side. Thereby, the electric charge can be easily and accurately taken out for each pixel through the pixel electrodes.

Furthermore, when the common electrode is formed on the second radiation conversion layer side of the semiconductor layer, the common electrode can transmit a larger amount of fluorescence as long as the common electrode is a transparent electrode that can transmit the fluorescence. The light can enter the semiconductor layer.

Further, when the common electrode is formed on the second radiation conversion layer side in the semiconductor layer, the common electrode may be an optical filter capable of transmitting the fluorescence. Alternatively, an optical filter capable of transmitting the fluorescence may be interposed between the first radiation conversion layer and the second radiation conversion layer. In either case, fluorescence can be reliably incident on the semiconductor layer.

In this case, the optical filter transmits light in a wavelength region that can be converted into electric charge by the first radiation detection unit to the first radiation conversion layer side, and transmits light in a region other than the wavelength region. Is preferably a dichroic filter that reflects the light toward the second radiation conversion layer.

As a result, only the fluorescence in the wavelength region that can be converted into electric charge in the first radiation detection unit is incident on the first radiation conversion layer, so that the incident fluorescence is efficiently charged in the first radiation detection unit. In addition, the second charge detector can efficiently convert the fluorescent light outside the wavelength region into charges. Even in this case, the image quality of each radiation image in the first radiation conversion layer and the second radiation conversion layer can be easily realized.

In addition, it is preferable that the second charge detection unit includes a photodiode or an organic photoconductor that converts the fluorescence into a charge.

Here, when the second charge detection unit and the second radiation detection unit are sequentially stacked with respect to the first radiation conversion layer, the organic photoconductor includes the fluorescence in the fluorescence. It is preferable that light in a wavelength region that can be converted into electric charge by the first radiation detection unit is transmitted to the first radiation conversion layer side and that light outside the wavelength region can be absorbed.

Even in this case, only the fluorescence in the wavelength region that can be converted into electric charge in the first radiation detection unit is incident on the first radiation conversion layer. Thereby, the incident fluorescence can be efficiently converted into charges by the first radiation detection unit, and fluorescence other than the wavelength region can be reliably converted into charges by the organic photoconductor. Therefore, even with this configuration, it is possible to easily realize high image quality of each radiation image in the first radiation conversion layer and the second radiation conversion layer.

The first charge detection unit outputs a first radiation image corresponding to the charge taken out from the first radiation detection unit, and the second charge detection unit converts the fluorescence into the charge converted from the fluorescence. A corresponding second radiation image is output. Accordingly, the first radiographic image and the second radiographic image can be provided by the control unit that is provided in the radiographic apparatus and controls the first radiation conversion layer and the second radiation conversion layer, or an external image processing apparatus. If desired, a desired high-quality image for general imaging can be acquired.

It is a block diagram of the radiography system which has a radiography apparatus which concerns on this embodiment. It is a circuit block diagram of the radiography apparatus of FIG. 3A and 3B are explanatory views showing a schematic configuration of the radiation conversion panel of FIG. 4A and 4B are explanatory views showing a schematic configuration of the radiation conversion panel of FIG. 5A and 5B are explanatory diagrams schematically showing the configuration of one pixel of the radiation conversion panel of FIG. 3A. 6A and 6B are explanatory diagrams illustrating a schematic configuration of the switching filter. 7A and 7B are explanatory diagrams illustrating a schematic configuration of the switching filter. It is explanatory drawing which shows schematic structure of a switching filter. FIG. 9A and FIG. 9B are explanatory views schematically showing another configuration of one pixel of the radiation conversion panel. 10A and 10B are explanatory diagrams schematically illustrating another configuration of one pixel of the radiation conversion panel. It is a graph which shows the relationship between the quantum efficiency of a-Se, and a sensitivity wavelength. It is a graph which shows the emission spectrum (relation between emission wavelength and normalized intensity) of the scintillator which generates the fluorescence of blue wavelength. 6 is a graph illustrating the relationship between the electric field of a-Se and the relative signal intensity. 14A to 14D are explanatory views showing an example of a manufacturing process of the radiation conversion panel of FIG. 3A. 15A to 15D are explanatory views showing an example of a manufacturing process of the radiation conversion panel of FIG. 3A. 16A to 16C are explanatory views showing an example of a manufacturing process of the radiation conversion panel of FIG. 3A. 17A to 17C are explanatory views showing an example of a manufacturing process of the radiation conversion panel of FIG. 3A. 18A to 18C are explanatory views showing an example of a manufacturing process of the radiation conversion panel of FIG. 3A. 19A and 19B are explanatory views showing an example of a manufacturing process of the radiation conversion panel of FIG. 3A. 20A is an explanatory diagram schematically showing the configuration of one pixel of the radiation conversion panel of FIG. 3B, and FIG. 20B is an explanation schematically showing the configuration of one pixel of the radiation conversion panel of FIG. 4A. FIG. 21A and 21B are plan views schematically showing the arrangement of the organic photoconductor in FIG. 20B. It is the graph which illustrated the relationship between the energy of a radiation, and a radiation absorption coefficient. It is the graph which illustrated the relationship between the film thickness of selenium and a radiation absorption rate. It is the graph which illustrated the relationship between the film thickness of selenium, CsI, and GOS, and a radiation absorption rate. It is a perspective view of the radiography apparatus which concerns on a 1st modification. It is a perspective view which shows the state which isolate | separated the main-body part and extension part of the radiography apparatus of FIG. FIG. 27 is a plan view illustrating the main body portion and the extension portion of FIG. It is sectional drawing of the main-body part and extension part of FIG.26 and FIG.27. 5 is a graph showing the relationship between the temperature of a-Si and the leakage current. It is a perspective view of the radiography apparatus which concerns on a 2nd modification. It is the perspective view which illustrated the state which the housing | casing of FIG. 30, the radiation detection unit, and the thermal radiation unit have isolate | separated. FIG. 31 is a cross-sectional view taken along line XXXII-XXXII in FIG. 30. It is sectional drawing of the radiography apparatus which concerns on a 3rd modification. It is explanatory drawing of the temperature control unit of FIG. It is a perspective view which shows the state which incorporated the radiography apparatus which concerns on a 4th modification in the imaging stand. It is the perspective view which illustrated integration of the radiography apparatus to an imaging stand. It is the perspective view which illustrated loading to the cradle of the radiography apparatus which concerns on a 5th modification. FIG. 38 is a side view illustrating a state in which a radiation imaging apparatus is loaded in the cradle of FIG. 37 with a part of the cradle cut away. It is a top view of the cradle of FIG. It is a schematic block diagram of the cradle of FIG. It is the side view which fractured | ruptured a part of cradle and illustrated the state which injected the disinfection liquid with respect to the radiography apparatus with which the cradle was loaded. It is the side view which fractured | ruptured and illustrated the state which blown air with respect to the radiography apparatus with which the cradle was loaded. FIG. 3 is a side view illustrating the removal of the radiation imaging apparatus from the cradle with a part of the cradle cut away. It is explanatory drawing which showed typically the structure for 1 pixel in the radiography apparatus which concerns on a 6th modification.

A preferred embodiment of the radiation imaging apparatus according to the present invention will be described below in detail with reference to FIGS.

[Configuration of this embodiment]
As shown in FIG. 1, the radiation imaging system 12 including the radiation imaging apparatus 10 according to the present embodiment detects a radiation output device 18 that irradiates the subject 14 with radiation 16 and the radiation 16 that has passed through the subject 14. The radiation imaging apparatus 10 for converting to a radiation image, the console 20 for controlling the radiation imaging apparatus 10 and the radiation output apparatus 18, and the display device 22 for displaying the radiation image are provided.

Between the console 20 and the radiation imaging apparatus 10, the radiation output apparatus 18, and the display apparatus 22, for example, a wireless local area network (UWB) such as UWB (Ultra Wide Band), IEEE802.11a / b / g / n, or Signals are transmitted and received by wireless communication using millimeter waves or the like. It goes without saying that signals may be transmitted and received by wired communication using a cable.

Connected to the console 20 is a radiology information system (RIS) 24 that comprehensively manages radiographic images and other information handled in the radiology department in the hospital. Connected to the RIS 24 is a medical information system (HIS) 26 that comprehensively manages medical information in the hospital.

The radiation imaging apparatus 10 according to the present embodiment includes, for example, a radiation conversion panel 28 that is disposed between an imaging table (not shown) and a subject 14 and converts radiation 16 transmitted through the subject 14 into a radiation image. It is a portable electronic cassette housed in a transmissive case. The radiation imaging apparatus 10 is not limited to a portable electronic cassette, but can also be applied to a built-in electronic cassette that is used by being mounted on an imaging table (not shown).

The radiation imaging apparatus 10 accommodates the above-described radiation conversion panel 28, cassette control unit 34, communication unit 36, and battery 38 in a housing. The cassette control unit 34 controls the radiation conversion panel 28 through the drive circuit unit 30 and reads out an electrical signal corresponding to the radiation image from the radiation conversion panel 28 through the readout circuit unit 32. The communication unit 36 transmits and receives signals to and from the console 20. The battery 38 supplies power to each unit in the radiation imaging apparatus 10.

The radiation conversion panel 28 is configured by sequentially laminating a first radiation conversion layer 28a, a switching filter 28b, and a second radiation conversion layer 28c along the incident direction of the radiation 16. In the present embodiment, the switching filter 28b is not essential as will be described later, and can be omitted. Therefore, the radiation conversion panel 28 can also employ a laminated structure of the first radiation conversion layer 28a and the second radiation conversion layer 28c. However, in the following description, a laminated structure including the switching filter 28b will be mainly described.

The first radiation converting layer 28a mainly absorbs a low energy component of the radiation 16 and directly converts the absorbed energy component into a charge, thereby forming a first radiation image corresponding to the charge. It is a radiation conversion layer. The second radiation conversion layer 28c mainly absorbs the high energy component of the radiation 16, temporarily converts the absorbed energy component into fluorescence, and converts the converted fluorescence into electric charge. It is an indirect conversion type radiation conversion layer which forms the radiation image of this.

According to control from the filter control unit 40, the switching filter 28b is in a transmission state (transparent state) capable of transmitting light in a specific wavelength region in the fluorescence, or shields the fluorescence to the second radiation conversion layer 28c side. It is a dichroic filter (optical filter) that switches to a non-transmissive state (mirror state) for reflection.

The low energy component of the radiation 16 is an energy component of the radiation 16 corresponding to the low voltage when the tube voltage of the radiation source constituting the radiation output device 18 is relatively low. It is easily absorbed by mammo, soft tissue or tumor. The high energy component of the radiation 16 is an energy component of the radiation 16 corresponding to the high voltage when the tube voltage of the radiation source is relatively high, and is easily absorbed by the bone portion of the subject 14. .

The radiation imaging apparatus 10 is also provided with a voltage supply unit 42 that supplies a DC voltage necessary for taking out the charges converted in the first radiation conversion layer 28a to the first radiation conversion layer 28a.

The cassette control unit 34 includes an address signal generation unit 44, an image memory 46, and a cassette ID memory 48. The address signal generation unit 44 supplies an address signal for instructing the radiation conversion panel 28 to read out a radiation image to the drive circuit unit 30. The image memory 46 stores a radiation image read from the radiation conversion panel 28 via the readout circuit unit 32 under the control of the drive circuit unit 30. The cassette ID memory 48 stores cassette ID information for specifying the radiation imaging apparatus 10.

The console (image processing apparatus) 20 includes a communication unit 50, a control processing unit 52, an order information storage unit 54, an imaging condition storage unit 56, an image processing unit 58, and an image memory 60.

The communication unit 50 transmits and receives signals to and from the communication unit 36, the radiation output device 18, the display device 22, and the RIS 24. The control processing unit 52 executes predetermined control processing for controlling each unit in the console 20. The order information storage unit 54 stores order information for requesting radiographic imaging (radiographic imaging) of the subject 14. The imaging condition storage unit 56 stores imaging conditions for irradiating the subject 14 with the radiation 16 and the like. The image processing unit 58 performs predetermined image processing on the radiation image received by the communication unit 50 from the communication unit 36. The image memory 60 stores a radiation image or the like that has been subjected to image processing by the image processing unit 58.

The order information is created by a doctor in the RIS 24 or HIS 26 and used for radiographic image capturing in addition to subject information for identifying the subject 14 such as the name, age, and sex of the subject 14. Information on the radiation output device 18 and the radiation imaging apparatus 10, the imaging region and imaging method of the subject 14, and the like. The imaging conditions are various conditions necessary for irradiating the imaging region of the subject 14 with the radiation 16 such as the tube voltage and tube current of the radiation source, the exposure time of the radiation 16, and the like.

FIG. 2 is a circuit configuration diagram of the radiation conversion panel 28 and the like constituting the radiation imaging apparatus 10.

As described above, the radiation conversion panel 28 has a stacked structure in which the first radiation conversion layer 28a, the switching filter 28b, and the second radiation conversion layer 28c are sequentially stacked along the incident direction of the radiation 16 (see FIG. 1). It is. In addition, the radiation conversion panel 28 has a structure in which a plurality of pixels 62 are arranged in a matrix in the plan view of FIG. In this case, each pixel 62 includes a part of the first radiation conversion layer 28a, a part of the switching filter 28b, and a part of the second radiation conversion layer 28c along the incident direction of the radiation 16. Has been.

Therefore, each pixel 62 directly converts the low energy component of the radiation 16 into an electric charge in the portion of the first radiation conversion layer 28a, and fluoresces the high energy component of the radiation 16 in the portion of the second radiation conversion layer 28c. Is converted into electric charge and then switched to a transmission state or a mirror state in accordance with control from the filter control unit 40 in the switching filter 28b.

In the radiation conversion panel 28, a plurality of

gate lines

64a and 64c extend in parallel to the row direction, and a plurality of

signal lines

66a and 66c extend in parallel to the column direction. The gate lines 64 a and 64 c are connected to the drive circuit unit 30, and the

signal lines

66 a and 66 c are connected to the readout circuit unit 32.

As described above, each pixel 62 includes a part of the first radiation conversion layer 28a, a part of the switching filter 28b, and a part of the second radiation conversion layer 28c. Therefore, for each pixel 62 arranged in the row direction, one gate line 64a connected to the first radiation conversion layer 28a (the TFT) and the second radiation conversion layer 28c (the TFT) are connected. Two gate lines are connected to one gate line 64c to be connected. For each pixel 62 arranged in the column direction, one signal line 66a connected to the first radiation conversion layer 28a (TFT) and the second radiation conversion layer 28c (TFT). There are two signal lines, one signal line 66c connected to the other.

Then, since the charges generated due to the absorption of the radiation 16 are accumulated in the radiation conversion layers 28a and 28c, the charges of the radiation conversion layers 28a and 28c are sequentially turned on for each row. Can be read out as an electrical signal.

Specifically, when an address signal is supplied from the address signal generation unit 44 of the cassette control unit 34 to the drive circuit unit 30, the TFTs arranged in the row direction are turned on and off from the drive circuit unit 30 to the

gate lines

64a and 64c. A control signal to be controlled is supplied. When the TFT is turned on by supplying the control signal, the charge held in each pixel 62 connected to the turned-on TFT flows out to the readout circuit section 32 through the TFT and the

signal lines

66a and 66c. The readout circuit unit 32 amplifies an electric signal (analog signal) corresponding to the inflowed charge, performs A / D conversion, and supplies the radiographic image converted into the digital signal to the cassette control unit 34.

[Configuration of the first to fourth embodiments]
3A to 4B schematically show a schematic configuration of the radiation conversion panel 28. FIG. In the following description, the configuration of FIGS. 3A to 4B is also referred to as first to fourth embodiments.

In the first embodiment of FIG. 3A, an ISS (Irradiation Side Sampling) type direct conversion type first radiation conversion layer 28a, a switching filter 28b, and a back surface along the incident direction of the radiation 16 are used. A configuration in which an indirect conversion type second radiation conversion layer 28c of a PSS (Penetration Side Sampling) method as a reading method is sequentially stacked is illustrated.

In the radiation conversion panel 28 of the first embodiment, the first radiation conversion layer 28a includes a thin insulating substrate 68a having flexibility along the incident direction of the radiation 16, a first charge detection unit 70a, and the like. The first radiation detection unit 72a is sequentially stacked. In addition, the second radiation conversion layer 28c has a flexible thin insulating substrate 68c toward the first radiation conversion layer 28a (from the lower side to the upper side in FIG. 3A) and the second radiation conversion layer 28c. The charge detection unit 70c and the second radiation detection unit 72c are sequentially stacked.

Since the insulating substrate 68a absorbs the radiation 16 in the first radiation detecting unit 72a and the second radiation detecting unit 72c, the insulating substrate 68a has a low electric absorption property of the radiation 16 and has a thin and electrically insulating property. A substrate (a substrate having a thickness of about several tens of μm) is preferable. Specifically, the insulating substrate 68a is preferably made of synthetic resin, aramid, bionanofiber, or film glass (ultra thin glass) that can be wound into a roll.

The first radiation detection unit 72a includes a semiconductor layer 74a made of amorphous selenium (a-Se), a plurality of pixel electrodes 76a formed on one surface of the semiconductor layer 74a on the first charge detection unit 70a side, and a semiconductor layer And a common electrode 78a formed so as to entirely cover the other surface of 74a.

The pixel electrode 76a is formed for each pixel 62, and is made of a conductive material (for example, Au) that has low absorbability with respect to the radiation 16 and does not generate electromigration with a-Se. Is preferred. When the radiation 16 is incident, the a-Se semiconductor layer 74a absorbs the low energy component of the radiation 16 and converts it into electric charges.

The common electrode 78a has low radiation 16 absorption, does not generate electromigration with a-Se, and transmits at least light in the sensitivity wavelength region of a-Se (for example, light in the blue wavelength region). It is preferably made of a possible conductive material, for example, ITO (Indium Tin Oxide). By configuring the common electrode 78a with such a conductive material, the second radiation detector 72c detects the high energy component of the radiation 16, and, as will be described later, the second radiation conversion layer 28c causes the radiation 16 to be detected. Can transmit light in at least the sensitivity wavelength region of a-Se.

Note that when the pixel electrode 76a and the common electrode 78a are formed, a-Se may be crystallized depending on the formation temperature. Therefore, in order to suppress crystallization of a-Se, it is necessary to form the pixel electrode 76a and the common electrode 78a at as low a temperature as possible. Therefore, the pixel electrode 76a and the common electrode 78a are desirably formed as an organic film or an organic conductor containing a metal filler by coating, roll-to-roll, ink jet, or the like.

The first charge detection unit 70a is configured to include the above-described TFT, and the charge generated in the semiconductor layer 74a is taken out for each pixel 62 through each pixel electrode 76a, and the taken-out charge is used as an electric signal (analog signal). The data is output to the readout circuit section 32 via the signal line 66a (see FIG. 2). In addition, the first charge detection unit 70a is preferably made of a material having low absorption of the radiation 16 so that the first radiation detection unit 72a and the like detect the radiation 16. Furthermore, since the gate line 64a and the signal line 66a are connected to the TFT, the gate line 64a and the signal line 66a also have a low-resistance conductive material (for example, low absorption of radiation 16). , Al).

The switching filter 28b causes the second radiation detection unit 72c to detect the high energy component of the radiation 16, and transmits at least light in the sensitivity wavelength region of a-Se among the fluorescence generated by the second radiation detection unit 72c. Therefore, it is preferable that the material is made of a material that has low absorption of the radiation 16 and can transmit the light.

The 2nd radiation detection part 72c consists of a scintillator which converts the high energy component of the incident radiation 16 into fluorescence. The scintillator can generate light in the a-Se sensitivity wavelength region and light in the wavelength region that can be absorbed by the second charge detector 70c (light having a longer wavelength than light in the a-Se sensitivity wavelength region). Such a scintillator that generates fluorescence having a relatively wide wavelength range is desirable. Examples of such a scintillator include CsI: Na, CaWO ₄ , YTaO ₄ : Nb, BaFX: Eu (X is Br or Cl), LaOBr: Tm, and the like, and CsI: Na is more preferable.

The second charge detection unit 70c is configured to include the above-described photoelectric conversion elements such as TFTs and photodiodes, converts the fluorescence converted by the scintillator into charges, and signals the converted charges as electric signals (analog signals). The data is output to the readout circuit unit 32 via the line 66c. In the configuration of the first embodiment, the low energy component of the radiation 16 is absorbed by the a-Se semiconductor layer 74a and converted into electric charges, and the high energy component of the radiation 16 is converted into the second radiation detection unit 72c. It is absorbed by the scintillator and converted into fluorescence. For this reason, in the first embodiment, the TFT and the photoelectric conversion element of the second charge detection unit 70c need not use a material having low radiation 16 absorption. Also, the gate line 64c and the signal line 66c connected to the TFT need not use a conductive material having low radiation 16 absorption.

Further, the second charge detection unit 70c that is unlikely to reach the radiation 16 is replaced with the above-described combination of TFT and photodiode, and has a CMOS (Complementary Metal-Oxide Semiconductor) image with low resistance to the radiation 16. You may combine TFT with other imaging elements, such as a sensor. Further, it can be replaced with a CCD (Charge-Coupled Device) image sensor that transfers charges while shifting charges by a shift pulse corresponding to a gate signal referred to as a TFT.

The radiation conversion panel 28 of the second embodiment shown in FIG. 3B includes an ISS direct conversion type first radiation conversion layer 28a, a switching filter 28b, and an ISS indirect conversion along the incident direction of the radiation 16. The second radiation conversion layer 28c of the mold is different from the first embodiment of FIG. 3A in that the second radiation conversion layer 28c is laminated in order.

In the description of the second to fourth embodiments shown in FIGS. 3B to 4B, only the configuration different from the first embodiment of FIG. 3A will be described.

In the radiation conversion panel 28 of the second embodiment, the second radiation conversion layer 28c includes an insulating substrate 68c, a second charge detection unit 70c, and a second radiation detection unit along the incident direction of the radiation 16. 72c and a reflection film 80c for reflecting the fluorescence generated by the second radiation detection unit 72c to the second radiation detection unit 72c side by layer.

The insulating substrate 68c needs to detect the radiation 16 in the second radiation detection unit 72c and transmit at least light in the a-Se sensitivity wavelength region among the fluorescence generated in the second radiation detection unit 72c. is there. Therefore, the insulating substrate 68c is an electrically insulating thin substrate having low radiation 16 absorbability and flexibility, as well as the insulating substrate 68a, and also has a light wavelength in the sensitivity wavelength region. Preferably, it is made of a material that can transmit light or has low light absorption and light shielding properties.

The second charge detection unit 70c causes the second radiation detection unit 72c to detect the radiation 16, and transmits at least the light in the sensitivity wavelength region of a-Se out of the fluorescence generated by the second radiation detection unit 72c. In order to achieve this, it is preferable that the radiation 16 has a low absorptivity and can transmit the light, or is made of a material having a low absorptivity and light shielding property.

In the second embodiment, the fluorescence generated by the second radiation detection unit 72c is incident on the first radiation conversion layer 28a via the second charge detection unit 70c and the insulating substrate 68c. There is a possibility that the amount of fluorescent light reaching the semiconductor layer 74a of the first radiation conversion layer 28a may be smaller than in the case of the embodiment.

In the third embodiment of FIG. 4A, the PSS direct conversion type first radiation conversion layer 28a, the switching filter 28b, and the ISS indirect conversion type second radiation are arranged along the incident direction of the radiation 16. The structure which laminated | stacked the conversion layer 28c in order is shown in figure.

In the radiation conversion panel 28 of the third embodiment, the first radiation conversion layer 28a includes a first radiation detection unit 72a, a first charge detection unit 70a, and an insulating substrate along the incident direction of the radiation 16. 68a are laminated in order. The first radiation detection unit 72a is configured by sequentially stacking a common electrode 78a, an a-Se semiconductor layer 74a, and each pixel electrode 76a along the incident direction of the radiation 16.

In the configuration of the third embodiment, it is unlikely that light in the a-Se sensitivity wavelength region described above reaches the common electrode 78a. Therefore, the common electrode 78a is made of a conductive material (for example, Au) that is impermeable to the light, does not generate electromigration with a-Se, and has low absorbability with respect to the radiation 16. It is preferable to become. By using Au having a resistance lower than that of ITO as an electrode, the voltage distribution in the semiconductor layer 74a is uniformized when the high voltage is applied to the common electrode 78a from the DC power source 106 (see FIG. 5A), and the power consumption is reduced. Reduction can be achieved.

On the other hand, the pixel electrodes 76a and the insulating substrate 68a are arranged on the second radiation conversion layer 28c side, unlike the first and second embodiments (see FIGS. 3A and 3B). Therefore, each of the pixel electrodes 76a and the insulating substrate 68a is preferably made of a material that is transmissive to the light and has low absorbability and light shielding properties for the radiation 16. Specifically, each pixel electrode 76a is preferably made of, for example, ITO that does not generate electromigration with a-Se. Since the pixel electrode 76a has a smaller area than the common electrode 78a, the resistance value may be slightly increased by using ITO. For the gate line 64a and the signal line 66a connected to the TFT, a metal such as Al that does not transmit light may be used in order to reduce resistance.

4A shows the case where the switching filter 28b is inserted between the two insulating

substrates

68a and 68c, the first radiation conversion layer 28a is provided on one surface of the insulating substrate. The second radiation conversion layer 28c may be disposed on the other surface, and the switching filter 28b may be interposed on either surface. In this case, like the insulating substrate 68a, the single insulating substrate is preferably a thin, electrically insulating substrate having low radiation 16 absorption and flexibility. If a single substrate is used, the absorption of the radiation 16 can be further reduced.

In the fourth embodiment shown in FIG. 4B, the PSS direct conversion type first radiation conversion layer 28a, the switching filter 28b, and the PSS indirect conversion type second are arranged along the incident direction of the radiation 16. The structure which laminated | stacked the radiation conversion layer 28c in order is illustrated.

[Details of Configuration of First Embodiment]
Next, of the radiation conversion panels 28 of the first to fourth embodiments described with reference to FIGS. 3A to 4B, the configuration of the first embodiment (see FIG. 3A) is typically shown in FIGS. 5A to 8. The details will be described. 5A to 8 schematically illustrate the radiation conversion panel 28 of the first embodiment in an enlarged manner to one pixel 62. FIG.

As described above, one pixel 62 includes a part of the first radiation conversion layer 28a, a part of the switching filter 28b, and a part of the second radiation conversion layer 28c.

More specifically, one pixel electrode 76a constituting the first radiation detection unit 72a is assigned to one pixel 62. 3A, for example, the pixel electrode 76a is made of Au, and the common electrode 78a is made of ITO.

The first charge detection unit 70 a has an array of TFTs 82 a disposed on the surface of the insulating substrate 68 a on the first radiation detection unit 72 a side, and one TFT 82 a is assigned to one pixel 62. It has been. In this case, when an array of TFTs 82a is formed on the insulating substrate 68a, the first radiation detecting portion 72a side of the insulating substrate 68a becomes uneven, so that, for example, a flattening process using a tetrafluoroethylene resin film is performed. It is desirable to form the planarizing film 84a.

The TFT 82a is connected to the gate line 64a and the signal line 66a (see FIG. 2) described above. The TFT 82a is an active material composed of amorphous silicon (a-Si), amorphous oxide (for example, a-IGZO (InGaZnO ₄ )), an organic semiconductor material, carbon nanotubes, etc. in order to suppress absorption of the radiation 16 in the TFT array. It is preferable that a layer is included and comprised.

In this case, since a-Si needs to be deposited at a substrate temperature of about 300 ° C., a glass substrate is used as the insulating substrate 68a. On the other hand, since a-IGZO and organic semiconductor can be formed by a low temperature process at a substrate temperature of about 200 ° C., a resin substrate such as polyimide or aramid can be used as the insulating substrate 68a. As a result, a flexible TFT array can be realized.

The pixel electrode 76a and the common electrode 78a are electrically connected to the voltage supply unit 42.

On the other hand, the second charge detection unit 70 c has an array of TFTs 82 c and photodiodes 86 c disposed on the surface of the insulating substrate 68 c on the second radiation detection unit 72 c side. One TFT 82c and one photodiode 86c are assigned. Also in this case, when an array of TFTs 82c and photodiodes 86c is formed on the insulating substrate 68c, the second radiation detector 72c side of the insulating substrate 68c becomes uneven, so that the same planarization as the planarizing film 84a is performed. It is desirable to form the film 84c.

The TFT 82c is connected to the gate line 64c and the signal line 66c described above. The TFT 82c preferably includes the same active layer as the TFT 82a. Furthermore, the photodiode 86c is preferably made of, for example, a-Si.

5A and 5B illustrate a CsI: Na (sodium-activated cesium iodide) scintillator as the second radiation detection unit 72c. The CsI: Na scintillator is formed by forming CsI: Na into a strip-like columnar crystal structure 88c by a vacuum deposition method. In this case, the base end portion of the scintillator on the flattening film 84c side is a non-columnar crystal portion 90c and is in close contact with the flattening film 84c. By providing the non-columnar crystal portion 90c, the adhesion between the scintillator of the second radiation detection unit 72c, the second charge detection unit 70c, and the insulating substrate 68c can be enhanced. Further, by reducing the porosity of the non-columnar crystal portion 90c to 0% or reducing the thickness thereof (for example, up to about 10 μm), reflection of fluorescence 98 described later can be suppressed.

Each column constituting the columnar crystal structure 88c is formed along the incident direction of the radiation 16, and a certain amount of gap is secured between adjacent columns. Further, the CsI: Na scintillator has characteristics that the columnar crystal structure 88c is weak against humidity and the non-columnar crystal portion 90c is particularly vulnerable to humidity. It is sealed. And the tip part of the columnar crystal structure 88c and the switching filter 28b are in close contact with the scintillator sealed with the moisture-proof protective material 92c.

Thus, the radiation conversion panel 28 of the first embodiment includes the first radiation conversion layer 28a including the a-Se semiconductor layer 74a, the switching filter 28b, and the scintillator of the columnar crystal structure 88c of CsI: Na. It has a laminated structure with the second radiation conversion layer 28c. In the radiation conversion panel 28, as shown in FIG. 5B, when the radiation 16 is incident, first, the a-Se semiconductor layer 74a absorbs the low energy component of the radiation 16 to generate a positive charge 94a and a negative charge 96a. Convert to charge pair.

Further, the radiation 16 (high energy component thereof) that has not been absorbed by the a-Se semiconductor layer 74a passes through the common electrode 78a and the switching filter 28b and reaches the second radiation detection unit 72c.

In the second radiation detection unit 72 c, the columnar crystal structure 88 c (its light emitting portion 100) absorbs the high energy component of the radiation 16 and converts it into fluorescence 98. A part of the fluorescent light 98 generated at the light emitting portion 100 (light in a long wavelength region exceeding 500 nm described later (light in the sensitivity wavelength region of the photodiode 86c)) is a columnar crystal formed substantially parallel to the incident direction of the radiation 16. Is propagated linearly (going straight) to the photodiode 86c. The photodiode 86c converts a part of the fluorescence 98 into electric charge and accumulates it.

Further, another part of the fluorescence 98 generated at the light emitting portion 100 travels straight through the columnar crystal toward the switching filter 28b.

Here, under the control of the filter control unit 40, the switching filter 28b transmits light in the short wavelength region of, for example, 500 nm or less including light in the a-Se sensitivity wavelength region (for example, light in the blue wavelength region). A case where the transmission state is switched will be described. In this case, of the fluorescence 98 that has reached the switching filter 28b, only light (transmitted light) 102 in the short wavelength region of 500 nm or less is transmitted through the switching filter 28b, and light (reflected light) 104 in the long wavelength region exceeding 500 nm is Reflected toward the second charge detector 70c.

As a result, the reflected light 104 travels straight through the columnar crystal to the photodiode 86c, and the photodiode 86c also converts the reflected light 104 into an electric charge and accumulates it. Therefore, when the TFT 82c is turned on by the control signal from the drive circuit unit 30, the charge corresponding to the fluorescence 98 and the reflected light 104 accumulated in the photodiode 86c flows out through the TFT 82c and flows through the signal line 66c. Can be output to the readout circuit section 32 as an electrical signal corresponding to the above.

On the other hand, the transmitted light 102 transmitted through the switching filter 28b passes through the common electrode 78a made of a transparent electrode such as ITO and reaches the a-Se semiconductor layer 74a. Since the transmitted light 102 is light in a short wavelength region of 500 nm or less (light in the sensitivity wavelength region of a-Se), the semiconductor layer 74a absorbs the transmitted light 102 and has a charge pair of a positive charge 94c and a negative charge 96c. Convert to

The DC power source 106 and the switch 108 of the voltage supply unit 42 are electrically connected to each pixel electrode 76a and the common electrode 78a. Here, when the switch 108 is turned on and a DC voltage is applied from the DC power source 106 such that each pixel electrode 76a has a positive polarity and the common electrode 78a has a negative polarity, a DC electric field is generated in the semiconductor layer 74a. According to this DC electric field, the

positive charges

94a and 94c move to the negative common electrode 78a side, and the

negative charges

96a and 96c move to the positive pixel electrode 76a side. As a result, the first charge detection unit 70a can extract the

negative charges

96a and 96c through the pixel electrodes 76a. When the TFT 82a is turned on by the control signal from the drive circuit unit 30, the first charge detection unit 70a passes through the signal line 66a. Thus, an electrical signal corresponding to the

negative charges

96a and 96c can be output to the readout circuit section 32.

Further, when a DC voltage that causes an avalanche effect in the semiconductor layer 74a is applied between each pixel electrode 76a and the common electrode 78a, the

positive charges

94a, 94c and

Negative charges

96a and 96c are amplified. As a result, the number of charges taken out by the first charge detector 70a (the TFT 82a) via each pixel electrode 76a can be increased.

5B shows a case where a DC voltage is applied so that each pixel electrode 76a has a positive polarity and common electrode 78a has a negative polarity. However, each pixel electrode 76a has a negative polarity and a common electrode 78a. Of course, the above effect can be obtained even when a positive DC voltage is applied.

Next, the configuration of the switching filter 28b will be described in detail with reference to FIGS. 6A to 8. FIG.

The switching filter 28b is a member having low absorbability with respect to the radiation 16, and, as shown in FIG. 6A, along the incident direction of the radiation 16 (see FIGS. 1, 3A to 4B, and 5B), the transparent base 110 The transparent conductive film 112, the ion storage layer 114, the solid electrolyte layer 116, the buffer layer 118, the catalyst layer 120, and the dimming mirror film layer 122 are laminated in this order. In this case, the DC power supply 124 and the switch 126 of the filter control unit 40 are electrically connected to the transparent conductive film 112 and the dimming mirror film layer 122.

The transparent substrate 110 is a vapor deposition substrate of the switching filter 28b disposed on the common electrode 78a side, and is a glass substrate or a plastic substrate that can transmit the transmitted light 102 (see FIGS. 5B and 6B). The transparent conductive film 112 is a transparent electrode made of ITO that can transmit the transmitted light 102. The ion storage layer 114 is a thin film made of WO ₃ capable of storing hydrogen ions (H ⁺ ). The solid electrolyte layer 116 is a thin film made of Ta ₂ O ₅ . The buffer layer 118 is an Al metal film. The catalyst layer 120 is a thin film made of Pd.

The dimming mirror film layer 122 is made of an Mg / Ni-based alloy thin film, and is caused by applying a DC voltage from the DC power source 124 to the transparent conductive film 112 and the dimming mirror film layer 122 when the switch 126 is turned on. A transparent state (transmission state) in which light having a wavelength of 500 nm or less including the sensitivity wavelength region of Se is transmitted as transmitted light 102, or a mirror state in which fluorescence 98 is reflected as reflected light 104 toward the second radiation detection unit 72c ( (Non-transparent state). In the transparent state, the light control mirror film layer 122 reflects light in a long wavelength region exceeding 500 nm to the second radiation detection unit 72c side as reflected light 104.

Here, switching of the mirror state or the transparent state in the light control mirror film layer 122 will be specifically described.

The surface of the light control mirror film layer 122 is normally in a mirror state (mirror) that reflects the fluorescence 98 as reflected light 104 toward the second radiation detection unit 72c due to the metallic luster of the Mg / Ni alloy thin film. State).

When the light control mirror film layer 122 is in such a mirror state, as shown in FIG. 6B, the switch 126 is turned on so that the transparent conductive film 112 becomes positive and the light control mirror film layer 122 has negative polarity. When a DC voltage (DC voltage of several volts) is applied to the switching filter 28b, the dimming mirror film layer 122 switches from the mirror state to the transparent state. This is because the hydrogen ions (H ⁺ ) stored in the ion storage layer 114 move to the dimming mirror film layer 122 through the solid electrolyte layer 116, the buffer layer 118, and the catalyst layer 120, thereby forming a metal state. This is because the Mg / Ni-based alloy is hydrogenated to a non-metallic state and becomes transparent.

When the dimming mirror film layer 122 once becomes transparent as described above, as shown in FIG. 7A, even if the switch 126 is turned off and voltage application (energization) from the DC power supply 124 to the switching filter 28b is stopped. The transparent state of the light control mirror film layer 122 is maintained.

Therefore, when the dimming mirror film layer 122 is in the transparent state, as described above, light in the short wavelength region of 500 nm or less out of the fluorescence 98 passes through the first radiation detection unit 72a as the transmitted light 102. At the same time, light in a long wavelength region exceeding 500 nm is reflected as reflected light 104 toward the second radiation detector 72c.

On the other hand, when the dimming mirror film layer 122 is in a transparent state, as shown in FIG. 7B, the switch 126 is turned on so that the dimming mirror film layer 122 becomes positive and the transparent conductive film 112 becomes negative. Thus, when a DC voltage having a polarity opposite to the voltage polarity shown in FIG. 6B (DC voltage of several volts) is applied to the switching filter 28b, the dimming mirror film layer 122 is switched from the transparent state to the mirror state. This is because hydrogen ions once moved to the light control mirror film layer 122 are transferred to the ion storage layer 114 via the catalyst layer 120, the buffer layer 118, and the solid electrolyte layer 116 due to the application of the reverse polarity DC voltage. This is because the light control mirror film layer 122 changes to the original metal state by returning.

When the light control mirror film layer 122 returns to the mirror state in this way, as shown in FIG. 8, even if the application of the DC voltage from the DC power supply 124 to the switching filter 28b is stopped by turning off the switch 126, the light control The mirror state of the optical mirror film layer 122 is maintained.

Therefore, when the light control mirror film layer 122 is in the mirror state, the fluorescence 98 in all wavelength regions is reflected as the reflected light 104 toward the second radiation detection unit 72c as described above.

The first embodiment is not limited to the above-described configuration, and may have the configuration shown in FIGS. 9A to 10B.

In FIG. 9A, the common electrode 78a transmits the fluorescent light 98 in the short wavelength region of 500 nm or less as the transmitted light 102, while the fluorescent light 98 in the long wavelength region longer than 500 nm is used as the reflected light 104, similarly to the switching filter 28b. The case where it functions as a dichroic filter (optical filter) to reflect is illustrated. Therefore, in the configuration of FIG. 9A, the switching filter 28b is omitted.

FIG. 9B differs from the configuration of FIG. 9A in that, in the second radiation detection unit 72c, the CsI: Na scintillator is configured only by the columnar crystal structure 88c, and the non-columnar crystal portion 90c does not exist. Since the non-columnar crystal portion 90c does not exist, it is possible to avoid the occurrence of reflection and scattering of the fluorescence 98 and the reflected light 104 on the first radiation conversion layer 28a side in the non-columnar crystal portion 90c.

FIG. 10A and FIG. 10B show that the second radiation detector 72c is replaced with a CsI: Na columnar crystal scintillator, CaWO ₄ , YTaO ₄ : Nb, BaFX: Eu (X is Br or Cl), or LaOBr. : Each of cases where a block scintillator coated with a fluorescent material such as Tm is hardened is illustrated.

These scintillators convert the transmitted light 102 into

charges

94c and 96c in the semiconductor layer 74a if the transmitted light 102 is linearly incident on the first radiation conversion layer 28a along the incident direction of the radiation 16. can do. On the other hand, these scintillators are more likely to scatter fluorescence 98 and reflected light 104 with the fluorescent material (particles) in the scintillator compared to columnar crystal scintillators, so that when the scattered light enters the photodiode 86c. This may cause image blurring of the second radiation image.

Therefore, when using these scintillators, (1) the reflected light 104 is absorbed by the switching filter 28b, (2) the switching filter 28b is omitted, or (3) the switching filter 28b is omitted and the common electrode is used. It is desirable to absorb the reflected light 104 at 78a.

[Operation of this embodiment (first example)]
Next, operation | movement of the radiography system 12 provided with the radiography apparatus 10 which concerns on this embodiment is demonstrated.

Here, the radiation imaging apparatus 10 has the radiation conversion panel 28 (see FIG. 3A) of the first embodiment, and a CsI: Na columnar crystal scintillator (see FIGS. 5A and 5B) as the second radiation detection unit 72c. ) Will be described.

First, the control processing unit 52 of the console 20 (see FIG. 1) acquires order information from the RIS 24 or the HIS 26, and stores the acquired order information in the order information storage unit 54.

Next, the control processing unit 52 changes the imaging region of the subject 14 from the radiation output device 18 to the imaging region of the subject 14 based on the imaging region and imaging method of the subject 14 and the information of the radiation imaging device 10 and the radiation output device 18 included in the order information. Imaging conditions (tube voltage, tube current, exposure time) for irradiating the radiation 16 are set, and the set imaging conditions and order information are stored in the imaging condition storage unit 56.

Further, the control processing unit 52 determines the state (transparent state or mirror state) of the switching filter 28b at the time of radiation imaging based on the imaging part and imaging method of the subject 14 included in the order information.

For example, if the imaging region is a mammo, the mammo can easily absorb the low energy component of the radiation 16. Therefore, the control processing unit 52 is such that the interpretation image requested by the order information is a radiation image corresponding to the low energy component, and the first radiation image of the low energy component can be acquired in the first radiation conversion layer 28a. Judge that it is desirable to perform radiography. Next, the control processing unit 52 creates instruction information for switching the switching filter 28 b to the transparent state, and stores the created instruction information in the imaging condition storage unit 56.

Also, if the imaging site is a bone part, the bone part is likely to absorb the high energy component of the radiation 16. Therefore, the control processing unit 52 is such that the interpretation image requested by the order information is a radiation image corresponding to the low energy component, and the second radiation image of the high energy component can be acquired in the second radiation conversion layer 28c. Judge that it is desirable to perform radiography. Next, the control processing unit 52 creates instruction information for switching the switching filter 28b to the mirror state, and stores the created instruction information in the imaging condition storage unit 56.

Furthermore, if the imaging region is the chest or abdomen, the control processing unit 52 is a radiographic image in which the interpretation image requested by the order information absorbs more energy components, and the second radiation conversion layer 28c General radiographing for acquiring two radiographic images, or general radiographing for obtaining an added image by acquiring the first and second radiographic images at each of the radiation conversion layers 28a and 28c and then adding them together. Judge that it is desirable. Next, the control processing unit 52 creates instruction information for switching the switching filter 28 b to the transparent state, and stores the created instruction information in the imaging condition storage unit 56.

Next, the doctor or engineer inserts the radiation imaging apparatus 10 between the subject 14 and the imaging table, and then positions the imaging region of the subject 14 with respect to the radiation imaging apparatus 10 and the radiation output apparatus 18.

In this case, the radiation output device 18 requests the console 20 to transmit imaging conditions and the like, and the control processing unit 52 performs the imaging condition storage unit 56 based on the transmission request of the radiation output device 18 received via the communication unit 50. The radiographing conditions stored in is transmitted to the radiation output device 18 via the communication unit 50 by radio.

On the other hand, in the radiation imaging apparatus 10, if power is supplied from the battery 38 to the cassette control unit 34 and the communication unit 36, the cassette control unit 34 transmits order information and the like to the console 20 via the communication unit 36. Request. The control processing unit 52 wirelessly transmits the order information, the imaging conditions, and the instruction information stored in the imaging condition storage unit 56 via the communication unit 50 based on the transmission request of the cassette control unit 34 received via the communication unit 50. Is transmitted to the radiation imaging apparatus 10. The cassette control unit 34 stores the order information, imaging conditions, and instruction information received via the communication unit 36 in the image memory 46 and / or the cassette ID memory 48.

Further, by supplying a bias voltage from the battery 38 to each pixel 62 (the photodiode 86c constituting the pixel), each photodiode 86c charges the fluorescence 98 and the reflected light 104 converted from the high energy component of the radiation 16. It becomes a state that can be accumulated by converting to.

Further, according to the voltage supply from the battery 38 and the control from the cassette control unit 34, the filter control unit 40 switches the switching filter 28b to the transparent state or the mirror state based on the instruction information.

The doctor or engineer turns on an exposure switch (not shown) on the assumption that preparation for imaging such as positioning of the subject 14 is completed. Accordingly, the control processing unit 52 captures the subject 14 by synchronizing the start of the output of the radiation 16 from the radiation output device 18 with the detection of the radiation 16 in the radiation conversion panel 28 and the conversion to the radiation image. A synchronization control signal for executing radiography for the region is generated. The control processing unit 52 transmits the generated synchronization control signal to the radiation imaging apparatus 10 and the radiation output apparatus 18 via the communication unit 50 wirelessly.

Thereby, when receiving the synchronization control signal, the radiation output device 18 irradiates the imaging region of the subject 14 with the radiation 16 having a predetermined dose according to the imaging conditions.

When the radiation 16 passes through the imaging region of the subject 14 and reaches the radiation conversion panel 28 in the radiation imaging apparatus 10, the a-Se semiconductor layer 74 a absorbs the low energy component of the radiation 16 to absorb positive charges 94 a and negative. A charge pair of charge 96a is generated. The high energy component of the radiation 16 that has not been absorbed by the semiconductor layer 74a reaches the second radiation detection unit 72c. The columnar crystal structure 88c absorbs a high energy component of the radiation 16 and generates fluorescence 98.

Here, if the switching filter 28b is in a transparent state, light in a short wavelength region of 500 nm or less including the sensitivity wavelength region of a-Se out of the fluorescence 98 passes through the switching filter 28b as transmitted light 102. On the other hand, light in a long wavelength region exceeding 500 nm is reflected as reflected light 104 in the switching filter 28b. Therefore, the semiconductor layer 74a can absorb the incident transmitted light 102 and generate a charge pair of a positive charge 94c and a negative charge 96c.

Here, if a DC voltage is applied from the voltage supply unit 42 to each pixel electrode 76a and the common electrode 78a and a DC electric field is generated in the semiconductor layer 74a, the

positive charges

94a and 94c and the

negative charges

96a and 96c are In accordance with the direct current electric field, the pixel electrode 76a or the common electrode 78a is moved. If the DC voltage (DC electric field) is sufficient to generate the avalanche effect, the

positive charges

94a and 94c and the

negative charges

96a and 96c are amplified by the avalanche effect, and thus the first charge is passed through each pixel electrode 76a. The number of charges taken out by the charge detection unit 70a can be increased.

Further, in the second charge detection unit 70c, the fluorescent light 98 generated at the light emitting point 100, propagates through the columnar crystal (goes straight) and reaches the photodiode 86c, is reflected by the switching filter 28b, and travels straight through the columnar crystal. Then, the reflected light 104 reaching the photodiode 86c is converted into charges and accumulated.

On the other hand, if the switching filter 28b is in a mirror state, all of the fluorescence 98 that has reached the switching filter 28b by going straight through the columnar crystal from the light emitting portion 100 is reflected as reflected light 104 regardless of the wavelength region. Therefore, the transmitted light 102 incident on the semiconductor layer 74a is not generated.

Therefore, when a DC voltage is applied from the voltage supply unit 42 between each pixel electrode 76a and the common electrode 78a, the positive charge 94a and the negative charge 96a are generated in the semiconductor layer 74a according to the DC electric field generated due to the DC voltage. Moves to each pixel electrode 76a or common electrode 78a. Further, if the DC voltage (DC electric field) is sufficient to generate the avalanche effect, the positive charge 94a and the negative charge 96a are amplified by the avalanche effect, and therefore the first charge detection unit 70a via each pixel electrode 76a. The number of charges taken out can be increased.

In the second charge detection unit 70c, the fluorescent light 98 generated at the light emitting point 100 and travels straight through the columnar crystal and reaches the photodiode 86c, and is reflected by the switching filter 28b, travels straight through the columnar crystal and travels to the photodiode 86c. The arrived reflected light 104 is converted into charges and accumulated.

Next, since the cassette control unit 34 receives the synchronization control signal via the communication unit 36, it is held in each pixel 62 by causing the address signal generation unit 44 to supply an address signal to the drive circuit unit 30. The charge information which is a radiographic image of the subject 14 is read out.

In this case, according to the address signal supplied from the address signal generating unit 44, the drive circuit unit 30 first passes the one row through the two

gate lines

64a and 64c connected to the pixels 62 in the first row. A control signal is supplied to the gates of the

TFTs

82a and 82c of each pixel 62 of the eye.

On the other hand, the readout circuit unit 32 displays the radiation image, which is the charge information held in each pixel 62 in the first row connected to the

gate lines

64a and 64c selected by the drive circuit unit 30, and the

signal lines

66a and 66c. Read sequentially.

The radiation image read from each pixel 62 in the first row connected to the selected

gate lines

64a and 64c is sampled after being amplified in the readout circuit unit 32 and converted into a digital signal by A / D conversion. The The radiographic image converted into the digital signal is temporarily stored in the image memory 46 of the cassette control unit 34.

The drive circuit unit 30 sequentially performs such an operation on each pixel 62 in each row in accordance with the address signal supplied from the address signal generation unit 44. As a result, the readout circuit unit 32 reads out the radiation image, which is the charge information held in each pixel 62 connected to each

gate line

64a, 64c, via the

signal line

66a, 66c, and the cassette control unit 34 It is stored in the image memory 46.

In this way, the radiation image obtained by the irradiation of the radiation 16 from the radiation output device 18 is stored in the image memory 46.

After storing the radiation image in the image memory 46, the cassette control unit 34 stores the radiation image (first radiation image acquired from the first radiation conversion layer 28a, second radiation conversion layer 28c) stored in the image memory 46. 2), the cassette ID information stored in the cassette ID memory 48, and the instruction information are wirelessly transmitted to the console 20 via the communication unit 36.

The control processing unit 52 of the console 20 outputs the radiographic image received via the communication unit 50 to the image processing unit 58, and sends an appropriate radiographic image corresponding to the instruction information to the image processing unit 58, that is, order information. Control is performed so as to generate an interpretation image that can be interpreted by a doctor according to the situation.

The image processing unit 58 selects the first radiographic image and selects the selected first radiographic image if it is radiographic imaging for acquiring a radiographic image corresponding to the low energy component of the radiation 16 such as radiography for mammo. After performing predetermined image processing on the radiation image, the first radiation image (interpretation image) after the image processing, the first radiation image and the second radiation image sent from the radiation imaging apparatus 10, The cassette ID information and the instruction information are stored in the image memory 60 in association with each other.

Further, the image processing unit 58 selects the second radiographic image and performs the predetermined image processing on the selected second radiographic image and then performs the image processing after the image processing for the general imaging of the chest or abdomen. The second radiation image (interpretation image), the first radiation image and the second radiation image sent from the radiation imaging apparatus 10, cassette ID information, and instruction information are associated with each other and stored in the image memory 60. To do. Alternatively, the image processing unit 58 performs an addition process of adding the first radiographic image and the second radiographic image in the case of general imaging, an image after addition (added image, interpretation image), and the radiographic apparatus The first radiation image and the second radiation image sent from 10, the cassette ID information, and the instruction information are stored in the image memory 60 in association with each other.

Further, the image processing unit 58 selects and selects the second radiographic image if it is radiographic imaging for acquiring a radiographic image corresponding to the high energy component of the radiation 16 such as radiographic imaging of the bone. After performing predetermined image processing on the second radiation image, the second radiation image (interpretation image) after the image processing, the first radiation image sent from the radiation imaging apparatus 10 and the second radiation image are sent. The radiation image, cassette ID information, and instruction information are stored in the image memory 60 in association with each other.

Then, the control processing unit 52 wirelessly transmits the interpretation image to the display device 22 via the communication unit 50, and the display device 22 displays the received interpretation image.

If the doctor or engineer visually recognizes the interpretation image displayed on the display device 22 and obtains a desired radiation image, the doctor or the engineer releases the subject 14 from the positioning state and ends the photographing with respect to the subject 14. On the other hand, if the interpretation image displayed on the display device 22 is not a desired radiation image, re-imaging is performed on the subject 14.

[Effect of this embodiment]
As described above, according to the radiation imaging apparatus 10 according to the present embodiment, the radiation imaging apparatus in which the direct conversion type first radiation conversion layer 28a and the indirect conversion type second radiation conversion layer 28c are stacked. 10, a part of the fluorescence 98 (light in a short wavelength region of 500 nm or less including light in the blue wavelength region) generated in the second radiation detection unit 72c is incident on the first radiation detection unit 72a, and the fluorescence 98 is emitted. The other part (light in a longer wavelength region than the short wavelength region exceeding 500 nm) is incident on the second charge detection unit 70c.

In this case, in the first radiation detection unit 72a, the radiation 16 is directly converted into the

charges

94a and 96a, and the transmitted light 102 which is a part of the incident fluorescence 98 is also converted into the

charges

94c and 96c. Therefore, in the first radiation conversion layer 28a, in addition to the

charges

94a and 96a directly converted from the radiation 16, the

charges

94c and 96c converted from the transmitted light 102 also form a radiation image in the first radiation conversion layer 28a. Will be used for.

Thereby, in this embodiment, the sensitivity of the first radiation detection unit 72a is increased without increasing the thickness of the first radiation detection unit 72a that constitutes the first radiation conversion layer 28a, and the first radiation conversion is performed. It becomes possible to acquire a high-quality radiation image with the layer 28a. Therefore, in the present embodiment, the radiation imaging apparatus 10 including the direct conversion type radiation conversion layer 28a that can be used for general imaging such as radiography for the chest and abdomen can be realized. In addition, since it is not necessary to increase the thickness of the first radiation detection unit 72a, the yield of the radiation imaging apparatus 10 including the first radiation conversion layer 28a can be improved.

Further, in the radiation imaging apparatus 10, the first radiation conversion layer 28a and the second radiation conversion layer 28c are sequentially laminated in the incident direction of the radiation 16. In this case, the first radiation detection unit 72a includes a semiconductor layer 74a that directly converts the radiation 16 into

charges

94a and 96a, and the second radiation detection unit 72c is a scintillator that converts the radiation 16 into fluorescence 98. is there.

Therefore, in the first radiation conversion layer 28a, the semiconductor layer 74a constituting the first radiation detection unit 72a absorbs the low energy component of the radiation 16 (energy component corresponding to the low tube voltage) and charges 94a and 96a. Convert directly to. On the other hand, in the second radiation conversion layer 28 c, the scintillator constituting the second radiation detection unit 72 c absorbs the high energy component of the radiation 16 (energy component corresponding to a high tube voltage) and converts it into fluorescence 98. Therefore, if a part of the fluorescence 98 corresponding to the high energy component enters the first radiation conversion layer 28a as the transmitted light 102, the semiconductor layer 74a can convert the transmitted light 102 into

charges

94c and 96c. .

As described above, in the radiation imaging apparatus 10, a so-called hybrid configuration of the semiconductor layer 74a and the scintillator can be adopted to efficiently convert the low energy component and the high energy component of the radiation 16 into charges. As a result, in the first radiation conversion layer 28a, a radiation image including a high energy component in addition to the low energy component of the radiation 16 can be formed.

Therefore, the first radiation conversion layer 28a easily realizes high image quality of radiographic images for general imaging such as radiography of the chest and abdomen and low-energy component radiographic images for mammo, soft tissue or tumor. In addition, the thickness of the semiconductor layer 74a can be avoided.

That is, in the semiconductor layer 74a, the low energy component of the radiation 16 is absorbed and converted into

charges

94a and 96a, and the transmitted light 102 corresponding to the high energy component is converted into

charges

94c and 96c. The unit 70a can form a radiation image that also reflects high energy components. As described above, since the first charge detection unit 70a is highly sensitive and can easily acquire a high-quality first radiation image, it is substantially the same as the case of the thick semiconductor layer 74a. Equivalent radiographic images can be obtained.

In the second radiation conversion layer 28c, a radiographic image including a high energy component can be formed, so that it is possible to form a radiographic image for general imaging or a radiographic image of a bone part.

If the semiconductor layer 74a is selenium, more preferably a-Se, a K edge is present on the low energy component side as shown in FIG. 22, and thus the low energy component of the radiation 16 is easily absorbed. Further, if a scintillator having a K edge on the high energy component side of a-Se is used for the second radiation detection unit 72c, a large amount of high energy component of the radiation 16 can be absorbed. By using such substances for the first radiation detection unit 72a and the second radiation detection unit 72c, the above-described effects can be easily obtained.

For example, in the case of a conventional radiation conversion panel using an a-Se semiconductor layer for mammography, the thickness of the semiconductor layer is about 200 μm at a tube voltage of 28 kV. On the other hand, in this embodiment, a part of the fluorescence 98 generated by the scintillator of the second radiation detection unit 72c is made incident on the semiconductor layer 74a as the transmitted light 102, thereby improving the sensitivity of the first radiation conversion layer 28a. Therefore, the thickness of the a-Se semiconductor layer 74a can be set to 200 μm or less.

Further, as shown in FIG. 11, a-Se has high quantum efficiency in a short wavelength region of 500 nm or less, and the quantum efficiency can be increased by increasing the DC electric field in the a-Se semiconductor layer 74a. That is, the a-Se semiconductor layer 74a has a short wavelength region of 500 nm or less including a blue wavelength region as a sensitivity wavelength region. For comparison, FIG. 11 also shows the sensitivity wavelength region of the photodiode 86c made of a-Si: H. The a-Si: H photodiode 86c has a long wavelength region exceeding 500 nm (specifically, a wavelength region of 500 nm to 600 nm) as a main sensitivity wavelength region.

Therefore, if the scintillator is at least a phosphor that generates fluorescence 98 in the blue wavelength region, the fluorescence 98 (transmitted light 102) in the blue wavelength region is incident on the semiconductor layer 74a of a-Se, so that the semiconductor In the layer 74a, the fluorescence 98 in the blue wavelength region can be efficiently photoelectrically converted into

charges

94c and 96c.

In order to obtain such an effect, in the present embodiment, as the scintillator used in the second radiation detection unit 72c, CsI: Na, CaWO ₄ , YTaO ₄ : Nb, BaFX: Eu (X is Br or Cl), or LaOBr: Tm or the like can be employed.

FIG. 12 shows, among these scintillators, typically the wavelength of the generated fluorescence 98 and its normalized intensity (the fluorescence 98 generated by the scintillator) in CsI: Na, CaWO ₄ , BaFBr: Eu, YTaO ₄ : Nb. The relationship between the maximum intensity and the value when normalized to 1.0) is shown. Among these scintillators, in particular, CsI: Na can generate fluorescence 98 in a wide wavelength region including a blue wavelength region of 500 nm or less and a long wavelength region exceeding 500 nm.

Therefore, when a scintillator made of CsI: Na is used for the second radiation detection unit 72c, the fluorescent light 98 (transmitted light 102) in the blue wavelength region is photoelectrically converted into

charges

94c and 96c by the a-Se semiconductor layer 74a. The fluorescent light 98 (and the reflected light 104) in the long wavelength region can be photoelectrically converted into electric charges in the photodiode 86c of the second charge detection unit 70c.

As a result, photoelectric conversion in the first radiation conversion layer 28a and the second radiation conversion layer 28c can be efficiently performed, and each radiation acquired in the first radiation conversion layer 28a and the second radiation conversion layer 28c. High image quality can be easily realized.

Further, if the a-Se semiconductor layer 74a is disposed on the radiation 16 incident side and the scintillator of the second radiation detector 72c is disposed behind the a-Se semiconductor layer 74a, the a-Se absorbs and transmits the soft X-rays. X-rays can be hardened. Thereby, even if glass (glass-made

insulating substrates

68a and 68c) is interposed between the semiconductor layer 74a and the scintillator, absorption of the radiation 16 by the glass can be suppressed. As a result, in a scintillator such as a CsI system, a BaFX system (X is Br or Cl), or GOS, hard X-rays can be reliably absorbed without reducing the radiation absorption rate. Since these scintillators tend to increase the emission intensity of fluorescence 98 as hard X-rays increase, the absorptive absorption of soft X-rays with a-Se can improve the radiation absorption rate of the scintillator. .

The first radiation detector 72a includes an a-Se semiconductor layer 74a, a plurality of pixel electrodes 76a, and a common electrode 78a. In this case, by applying a DC voltage between each pixel electrode 76a and the common electrode 78a,

positive charges

94a and 94c or

negative charges

96a and 96c generated in the semiconductor layer 74a are transmitted through the pixel electrodes 76a. It can be taken out by one charge detector 70a.

FIG. 13 shows the relative value of the detection signal intensity according to the DC electric field in the a-Se semiconductor layer 74a and the number of charges taken out by the first charge detection unit 70a (the detection signal intensity in the DC electric field of 10 V / μm). The relationship with the value when normalized to 1.0) is illustrated.

In this case, in a DC electric field up to 50 V / μm, the relative signal strength remains at a value near 1.0 as shown by the solid line. Therefore, the first charge detection unit 70a merely has a function of extracting only the

positive charges

94a and 94c or the

negative charges

96a and 96c generated in the a-Se semiconductor layer 74a by the irradiation of the radiation 16. Absent.

On the other hand, in a DC electric field of 80 V / μm or more, the relative signal strength increases to 10 to 100 as shown by the broken line. This is because carrier multiplication due to the avalanche effect occurs while the

electric charges

94a, 94c, 96a, and 96c travel in the a-Se semiconductor layer 74a due to a high electric field of 80 V / μm or more. As a result, the number of charges (detection signal intensity) taken out by the first charge detection unit 70a via each pixel electrode 76a can be easily increased.

In order to obtain such a charge number multiplication effect, the thickness of the a-Se semiconductor layer 74a may be reduced. That is, if the thickness of the a-Se semiconductor layer 74a is thin, a DC electric field generated in the semiconductor layer 74a when a DC voltage is applied between each pixel electrode 76a and the common electrode 78a increases, and an avalanche is formed. This is because the charge multiplying effect due to the effect is easily obtained.

As described above, if the semiconductor layer 74a is thinned, the first charge detection unit 70a has high sensitivity, so that a high-quality first radiation image can be easily acquired. Therefore, if the thickness of the semiconductor layer 74a is reduced, a radiation absorption rate and a radiation image substantially equivalent to those of the thick semiconductor layer 74a can be obtained.

Each pixel electrode 76a is formed on the first charge detection unit 70a side in the semiconductor layer 74a, and the common electrode 78a is formed on the opposite side of the semiconductor layer 74a from the first charge detection unit 70a side. ing. Therefore, the

positive charges

94a and 94c or the

negative charges

96a and 96c can be easily and accurately taken out for each pixel 62 through each pixel electrode 76a.

Furthermore, when the common electrode 78a is formed on the second radiation conversion layer 28c side of the semiconductor layer 74a, the common electrode 78a is a transparent electrode such as ITO that can transmit part of the fluorescence 98 as the transmitted light 102. A large amount of transmitted light 102 can be incident on the semiconductor layer 74a.

Further, a switching filter 28b as an optical filter capable of transmitting a part of the fluorescence 98 as the transmitted light 102 is interposed between the first radiation conversion layer 28a and the second radiation conversion layer 28c. Alternatively, when the common electrode 78a is formed on the second radiation conversion layer 28c side in the semiconductor layer 74a, the common electrode 78a may function as an optical filter capable of transmitting the transmitted light 102. In any case, light in the short wavelength region including the blue wavelength region of the fluorescence 98 can be reliably incident on the semiconductor layer 74a as the transmitted light 102.

The switching electrode 28b or the common electrode 78a functioning as an optical filter transmits light in the sensitivity wavelength region that can be converted into

charges

94c and 96c by the a-Se semiconductor layer 74a in the fluorescent light 98. And a dichroic filter that transmits light outside the sensitivity wavelength region as reflected light 104 to the second radiation conversion layer 28c side.

Thus, since only the fluorescence 98 (transmitted light 102) in the sensitivity wavelength region that can be converted into

charges

94c and 96c in the semiconductor layer 74a is incident on the semiconductor layer 74a, the incident transmitted light 102 is efficiently charged in the semiconductor layer 74a. 94c and 96c, and fluorescence 98 and reflected light 104 outside the sensitivity wavelength region can be efficiently converted into charges by the photodiode 86c of the second charge detection unit 70c. Thereby, further improvement in the image quality of each radiation image in the 1st radiation conversion layer 28a and the 2nd radiation conversion layer 28c is easily realizable.

In addition, it is desirable that the common electrode 78a functioning as the switching filter 28b or the optical filter functions as follows according to the type of scintillator used in the second radiation detection unit 72c.

When a CsI columnar crystal scintillator is used, the switching filter 28b or the common electrode 78a transmits the fluorescence 98 having a wavelength of 500 nm or less as the transmitted light 102 and reflects the fluorescence 98 having a wavelength exceeding 500 nm as reflected light, as described above. What is necessary is just to function as a dichroic filter which reflects as 104. As a result, the transmitted light 102 is converted into

charges

94c and 96c in the semiconductor layer 74a, and the reflected light 104 is received by the photodiode 86c by the light guide effect that travels straight through the columnar crystal and reaches the photodiode 86c. And converted into electric charge. As a result, a high-quality first radiographic image is obtained, and a second radiographic image without image blur is obtained.

On the other hand, when a granular scintillator such as GOS is used, the switching filter 28b or the common electrode 78a transmits fluorescence 98 having a wavelength of 500 nm or less as transmitted light 102 and absorbs fluorescence 98 having a wavelength exceeding 500 nm. It only has to function. As a result, the transmitted light 102 is converted into

charges

94c and 96c in the semiconductor layer 74a, and the occurrence of light scattering at the scintillator particles due to reflection at the switching filter 28b or the common electrode 78a can be suppressed. . Even in this case, a high-quality first radiation image can be obtained, and a second radiation image without image blur can be obtained.

In the present embodiment, the image processing unit 58 of the console 20 uses the first radiation image formed by the first radiation conversion layer 28a and the second radiation image formed by the second radiation conversion layer 28c. By adding, a desired high-quality image for general photography can be easily acquired. Of course, the cassette control unit 34 may have such an image processing function to generate an addition image on the radiation imaging apparatus 10 side.

As described above, in the radiation imaging apparatus 10 according to the present embodiment, at least light in the sensitivity wavelength region of a-Se (transmitted light 102 in the blue wavelength region of 500 nm or less) is transmitted to the semiconductor of the first radiation conversion layer 28a. The switching filter 28b is not indispensable because the above-described effects associated with the incident of the transmitted light 102 can be obtained by making the light incident on the layer 74a. Accordingly, the radiation conversion panel 28 is configured by the laminated structure of the first radiation conversion layer 28a and the second radiation conversion layer 28c, and the fluorescence 98 converted from the high energy component of the radiation 16 by the second radiation detection unit 72c. May be incident on the semiconductor layer 74a of the first radiation detector 72a as transmitted light 102 as it is.

However, in radiography of the subject 14, depending on the radiographic part, the fluorescence 98 converted from the high energy component of the radiation 16 (a high voltage component with a relatively high tube voltage) is incident on the semiconductor layer 74 a as the transmitted light 102 and transmitted. When charges 94c and 96c caused by light are generated, an addition image is generated by adding the first radiation image and the second radiation image based on the

charges

94c and 96c. When interpreting images, it may be difficult to observe the imaged part reflected in the added image.

For example, in radiography for a soft tissue or tumor, an image in which a bone part is reflected is formed as a second radiographic image, so an addition image is formed by adding the first radiographic image and the second radiographic image. Then, there is a possibility that the bone part can be easily seen.

For such a problem, by inserting the switching filter 28b and making the switching filter 28b into a mirror state, only the light in the blue wavelength region of 500 nm or less is transmitted among the fluorescence 98 generated in the scintillator. While the light 102 is incident on the first radiation conversion layer 28a, light exceeding 500 nm may be shielded. In this way, by setting the switching filter 28b in a mirror state and intentionally blocking a part of the fluorescence 98 generated by the scintillator, an added image that can be easily interpreted by a doctor can be reliably acquired.

[Production method of radiation conversion panel]
Next, a method for manufacturing the radiation conversion panel 28 constituting the radiation imaging apparatus 10 according to the present embodiment will be described with reference to FIGS. 14A to 19B.

14A to 15D illustrate the manufacturing process of the radiation conversion panel 28 (see FIG. 3A) of the first embodiment.

First, as shown in FIG. 14A, a first charge detector 70a is formed on an insulating substrate 68a by a known vapor deposition technique. Next, as shown in FIG. 14B, a plurality of pixel electrodes 76a are formed on the first charge detection unit 70a by vapor deposition. Thereafter, as shown in FIG. 14C, an a-Se semiconductor layer 74a is formed on the first charge detection unit 70a and the pixel electrode 76a by vapor deposition. Next, as shown in FIG. 14D, a common electrode 78a is formed on the a-Se semiconductor layer 74a by vapor deposition.

On the other hand, as shown in FIG. 15A, the second charge detector 70c is formed on the insulating substrate 68c by vapor deposition. Next, as shown in FIG. 15B, a second radiation detection unit 72c (scintillator) is formed on the second charge detection unit 70c by vapor deposition. Thereafter, as shown in FIG. 15C, the switching filter 28b is attached to the second radiation detection unit 72c via the adhesive layer 128 (or adhesive layer). Finally, as shown in FIG. 15D, the common electrode 78a formed in the step of FIG. 14D and the switching filter 28b attached in the step of FIG. 15C are pasted through the adhesive layer 130 (or adhesive layer). To wear. Thereby, the radiation conversion panel 28 of the first embodiment is completed.

In the step of FIG. 15B, when a CsI: Na columnar crystal scintillator is deposited on the second charge detection unit 70c as the second radiation detection unit 72c, the tip of the columnar crystal structure 88c is as much as possible. It is preferably flat. Therefore, in the process of FIG. 15B, the temperature of the second charge detector 70c as the substrate for the scintillator and the temperature of the insulating substrate 68c are controlled at the final stage of vapor deposition of the CsI: Na scintillator on the second charge detector 70c. Thus, the tip portion of the columnar crystal structure 88c is made as flat as possible.

For example, the temperature of the second charge detection unit 70c and the insulating substrate 68c is 110 ° C., the angle of the tip portion of the columnar crystal structure 88c is 170 °, the temperature is 140 ° C., and the angle is 60 °. Is 200 ° C., the angle is 70 °, and the temperature is 260 ° C. and the angle is 120 °.

16A to 16C illustrate a first modification of the manufacturing process of FIGS. 14A to 15D.

In this case, first, as shown in FIG. 16A, the scintillator of the second radiation detection unit 72c is formed on the vapor deposition substrate 132 by vapor deposition via the release layer 134. Next, by irradiating the peeling layer 134 with a laser beam (not shown), as shown in FIG. 16B, the vapor deposition substrate 132 and the peeling layer 134 are peeled off from the second radiation detector 72c. Thereafter, as shown in FIG. 16C, the second charge detection unit 70c and the second radiation detection unit 72c formed on the insulating substrate 68c in the step of FIG. 15A are bonded to the adhesive layer 136 (or adhesive layer). To stick through. Then, the radiation conversion panel 28 can be obtained by performing the process of FIG. 15C and FIG. 15D.

FIGS. 17A to 17C illustrate a second modification of the manufacturing process of FIGS. 14A to 15D.

In this case, first, in FIG. 17A, the switching filter 28b is formed by vapor deposition on the common electrode 78a formed on the a-Se semiconductor layer 74a by the process of FIG. 14D. Next, as shown in FIG. 17B, the scintillator of the second radiation detector 72c is formed on the switching filter 28b by vapor deposition. Thereafter, as shown in FIG. 17C, the second charge detection unit 70c and the second radiation detection unit 72c formed on the insulating substrate 68c in the step of FIG. 15A are connected to the adhesive layer 136 (or adhesive layer). The radiation conversion panel 28 is obtained by sticking through the sheet.

FIGS. 18A to 19B illustrate a third modification of the manufacturing process of FIGS. 14A to 15D.

In this case, first, in FIG. 18A, the switching filter 28b is formed by vapor deposition on the second radiation detection unit 72c attached to the second charge detection unit 70c by the process of FIG. 16C. Next, as shown in FIG. 18B, a common electrode 78a is formed on the switching filter 28b by vapor deposition. Thereafter, as shown in FIG. 18C, an a-Se semiconductor layer 74a is formed on the common electrode 78a by vapor deposition. Next, as shown in FIG. 19A, a plurality of pixel electrodes 76a are formed on the semiconductor layer 74a. Finally, as shown in FIG. 19B, the first charge detector 70a formed on the insulating substrate 68a in the process of FIG. 14A, the plurality of pixel electrodes 76a and the semiconductor layer 74a are bonded to the adhesive layer 138 (or adhesive layer). ) To obtain the radiation conversion panel 28.

In the third modification, the surface of the semiconductor layer 74a on the side of the insulating substrate 68a becomes uneven by forming the plurality of pixel electrodes 76a on the semiconductor layer 74a, and thus the first charge detection unit 70a. The pixel electrode 76a and the semiconductor layer 74a are attached to each other via the adhesive layer 138, so that the adhesive layer 138 functions as a planarizing film.

In the description of FIGS. 14A to 19B, the case where the second radiation detector 72c is a CsI: Na columnar crystal scintillator has been described. However, when a scintillator having no columnar crystal such as CaWO ₄ is used. For the second radiation detection unit 72c described above, the term “deposition substrate 132” is replaced with “substrate such as PET”, and the term “deposition formed” is replaced with “application”. made to the description of the manufacturing process of the radiation conversion panel 28 using a scintillator of CaWO _4, or the like.

[Modification of this embodiment]
Next, a modification of the radiation imaging apparatus 10 according to the present embodiment will be described with reference to FIGS. 20A to 21B. In the following description, the same reference numerals are assigned to the same components as those described above, and the detailed description thereof is omitted.

20A is an enlarged view of the radiation conversion panel 28 (see FIG. 3B) of the second embodiment with respect to one pixel 62, and FIG. 20B shows the radiation conversion panel 28 (see FIG. 4A) of the third embodiment. ) Is enlarged and illustrated for one pixel 62.

In the second embodiment of FIG. 20A, the radiation 16 passes through the second charge detector 70c and the insulating substrate 68c, and is generated in the columnar crystal structure 88c of the CsI: Na scintillator of the second radiation detector 72c. In order to transmit the light in the short wavelength region including the sensitivity wavelength region of a-Se as the transmitted light 102 in the fluorescent light 98, the second charge detection unit 70c and the insulating substrate 68c have the absorption of the radiation 16. It is preferably made of a material that is low and can transmit the light, or has low light absorption and light shielding properties.

Specifically, in the second embodiment, the insulating substrate 68c is preferably made of the same material as the insulating substrate 68a. Similarly to the TFT 82a, the TFT 82c includes an active layer made of amorphous silicon (a-Si), amorphous oxide (for example, a-IGZO (InGaZnO ₄ )), an organic semiconductor material, a carbon nanotube, and the like. The diode 86c is also preferably made of a-Si. Therefore, the gate line 64c and the signal line 66c connected to the TFT 82c also have low radiation 16 absorptivity and can transmit the light, or have a low absorptivity and light shielding property. It is preferable to consist of materials.

Also in the second embodiment, the second radiation detection unit 72c absorbs the high energy component of the radiation 16 and converts it into fluorescence 98 at the light emitting portion 100 of the columnar crystal structure 88c. However, in the second embodiment, the fluorescence 98 generated at the light emitting portion 100 travels straight through the columnar crystal and directly reaches the photodiode 86c, or propagates through the columnar crystal to the reflection film 80c side and reflects the reflection film 80c. The reflected light 140 travels straight through the columnar crystal and reaches the photodiode 86c. Therefore, the photodiode 86c converts the fluorescent light 98 that has directly reached through the columnar crystal and the reflected light 140 into electric charges and accumulates them.

Here, as described with reference to FIG. 11, the a-Si: H photodiode 86c mainly converts light in a long wavelength region exceeding 500 nm into electric charges, and for light in a short wavelength region of 500 nm or less, Low efficiency. Therefore, in the second embodiment, the second charge detection unit 70c transmits and transmits light having a short wavelength region of 500 nm or less (for example, light in the blue wavelength region) out of the incident fluorescence 98 and reflected light 140. The light 102 is incident on the first radiation detector 72a. Thereby, the semiconductor layer 74a of the first radiation detection unit 72a can photoelectrically convert the incident transmitted light 102 into a charge pair of a positive charge 94c and a negative charge 96c. Therefore, the radiation conversion panel 28 of the second embodiment can achieve the same effect as that of the first embodiment.

20B, the insulating substrate 68a and the insulating substrate 68c are attached via the adhesive layer 142 (or adhesive layer). The second charge detector 70c includes an organic photoconductor 144c instead of the photodiode 86c. In this case, the TFT 82c and the organic photoconductor 144c are sequentially stacked along the incident direction of the radiation 16.

21A and 21B schematically show the planar arrangement of the organic photoconductor 144c in the second charge detection unit 70c, and one organic photoconductor 144c (and TFT 82c) is assigned to one pixel 62. It has been. As shown in FIGS. 21A and 21B, in the third embodiment, the second charge detectors 70c and the TFTs 82c are tiled in a matrix in a plan view.

The organic photoconductor 144c includes, for example, quinacridone so as to absorb the fluorescent light 98 in the green wavelength region (magenta color) and convert it into charges, or green (magenta) or red (cyan). It is preferable to absorb the fluorescence 98 in the wavelength region and convert it into charges.

FIG. 21A illustrates a case where all the organic photoconductors 144c that are tilingly arranged on the second charge detection unit 70c are photoelectric conversion elements that absorb fluorescence 98 in the green wavelength region.

FIG. 21B shows a photoelectric conversion element in which most of the organic photoconductors 144c among all the organic photoconductors 144c arranged on the second charge detection unit 70c absorb the fluorescence 98 in the green wavelength region. On the other hand, the case where some organic photoconductors 144c (shown by hatching in FIG. 21B) are photoelectric conversion elements that absorb fluorescence 98 in the red wavelength region is illustrated. Note that since red is difficult to refract the fluorescence 98 and may cause image blur of the second radiation image, the organic photoconductor 144c that absorbs the fluorescence 98 in the red wavelength region is the second one. What is necessary is just to use it as a sensor for a monitor for detecting the presence or absence of irradiation of the radiation | emission 16, without using for the sensor for image formation of a radiographic image.

In the radiation conversion panel 28 of the third embodiment, among the fluorescent light 98 and the reflected light 140 incident on the organic photoconductor 144c, the light in the green wavelength region or the light in the green wavelength region and the red wavelength region is emitted from the organic photoconductor 144c. It is absorbed by the conductor 144c and converted into electric charge. On the other hand, light in a shorter wavelength region (for example, light in the blue wavelength region) is transmitted as the transmitted light 102 through the organic photoconductor 144c, the TFT 82c, and the first charge detection unit 70a, so that the first radiation detection is performed. It reaches part 72a.

Thereby, the semiconductor layer 74a of the first radiation detection unit 72a can photoelectrically convert the incident transmitted light 102 into a charge pair of a positive charge 94c and a negative charge 96c. Therefore, the same effect as that of the first embodiment can be obtained in the radiation conversion panel 28 of the third embodiment.

Moreover, if the organic photoconductor 144c is used, the scintillator is not limited to the blue wavelength region, and a phosphor that generates a green wavelength region such as CsI: Tl or GOS can be used. Even when a CsI: Na scintillator is used, the organic photoconductor 144c can absorb light having a wavelength in the wavelength band from green to red, so that the light detection efficiency can be improved.

As described above, in the second and third embodiments described with reference to FIGS. 20A to 21B, even if the photodiode 86c or the organic photoconductor 144c is disposed in the middle of passing the transmitted light 102, the photodiode 86c or the organic The photoconductor 144c transmits the transmitted light 102 in the short wavelength region including the blue wavelength region which is the sensitivity wavelength region of a-Se, and absorbs the fluorescence 98 and the reflected light 140 in the longer wavelength region than the transmitted light 102. And convert it into electric charge Therefore, in the semiconductor layer 74a, the incident transmitted light 102 can be efficiently converted into

charges

94c and 96c, and in the photodiode 86c or the organic photoconductor 144c, light in a long wavelength region exceeding the sensitivity wavelength region is reliably converted into charges. Can be converted. Therefore, even with these configurations, it is possible to easily realize high image quality of each radiation image in the first radiation conversion layer 28a and the second radiation conversion layer 28c.

In the above description, the scintillator as the second radiation detection unit 72c is composed of one type of phosphor. However, in this embodiment, a scintillator in which a plurality of phosphors are blended can be used. is there.

Specifically, the sensitivity wavelength region of the first fluorescent substance that generates fluorescence 98 (transmitted light 102) in the sensitivity wavelength region of a-Se and the photodiode 86c or the organic photoconductor 144c of the second charge detection unit 70c. A scintillator configured by blending the fluorescent material 98 and the second fluorescent material that generates the reflected

lights

104 and 140 is used as the second radiation detection unit 72c.

In this case, in the indirect conversion type second radiation conversion layer 28c, the first fluorescent material that is not normally used is actively used as a constituent material of the scintillator. Here, when fluorescence 98 (for example, fluorescence 98 in the blue wavelength region) generated by the first fluorescent material is incident on the a-Se semiconductor layer 74a as transmitted light 102, the transmitted light 102 is transmitted in the semiconductor layer 74a. The

charges

94c and 96c can be reliably converted. On the other hand, the fluorescence 98 (for example, fluorescence 98 in the long wavelength region of 500 nm or more) generated by the second fluorescent material is reliably converted into charges by the photodiode 86c or the organic photoconductor 144c of the second charge detection unit 70c. be able to.

As described above, the scintillator obtained by selecting and blending the first fluorescent material and the second fluorescent material according to the characteristics of the semiconductor layer 74a and the characteristics of the photodiode 86c or the organic photoconductor 144c is used for the second radiation detection. Used as part 72c. Thus, the absorption energy of the radiation 16 is controlled without increasing the thickness of the a-Se semiconductor layer 74a, and a desired radiation image is obtained in the first radiation conversion layer 28a and the second radiation conversion layer 28c. It becomes possible to do.

For example, in the first radiation conversion layer 28a, a radiation image corresponding to a low energy component and a medium energy component (energy component corresponding to a low tube voltage and a medium tube voltage) of the radiation 16 or a low energy component to a high energy component. Absorbed by the semiconductor layer 74a by selecting the first fluorescent material for the purpose of acquiring a radiation image corresponding to a wide range of energy components from low to high tube voltages. The desired radiation image can be acquired by controlling the energy component.

The above-described blend scintillator will be described with specific examples of fluorescent materials.

BaFBr: Eu that mainly generates purple fluorescence at the K edge 37 keV is used as the first fluorescent material, GOS: Tb that mainly generates green fluorescence at the K edge 60 keV and generates blue fluorescence as the second fluorescence is used as the second fluorescence. As a substance, both are blended to form a scintillator. In this case, the fluorescence generated by GOS: Tb is mainly received by the photodiode 86c or the organic photoconductor 144c. A part of the fluorescence generated in BaFBr: Eu is also received by the photodiode 86c or the organic photoconductor 144c, but most of the fluorescence passes through the photodiode 86c or the organic photoconductor 144c, and is a semiconductor layer of a-Se. 74a enters as transmitted light 102.

Therefore, the TFT 82a obtains a first radiation image corresponding to the low energy component and the medium energy component, and the TFT 82c obtains a second radiation image corresponding to the high energy component. Moreover, if the first radiographic image and the second radiographic image are added, a radiographic image of a wide range of energy components from a low energy component to a high energy component can be obtained.

By the way, when the scintillator blended with the second embodiment of FIGS. 3B and 20A described above or the third embodiment of FIGS. 4A and 20B is applied, the transmitted light 102 passes through the second charge detection unit 70c. The a-Si TFT 82c may absorb the transmitted light 102 and cause switching noise. On the other hand, if violet light having low sensitivity in a-Si is passed through the second charge detection unit 70c as transmitted light 102, the a-Si TFT 82c absorbs the transmitted light 102. Since it is suppressed, generation | occurrence | production of switching noise can be suppressed.

[Other Modifications of this Embodiment]
Furthermore, the radiation imaging apparatus 10 according to the present embodiment can be modified to the modifications shown in FIGS. 25 to 44 (radiation imaging apparatuses 10A to 10F according to the first to sixth modifications).

[First Modification]
The radiation imaging apparatus 10A according to the first modification is basically used as a portable electronic cassette, and as shown in FIGS. 25 to 28, a hexahedral housing 150 that houses the radiation conversion panel 28 and the like. However, it can be separated into a large-capacity main body 150 a that accommodates the radiation conversion panel 28 and a small-capacity expansion portion 150 b that accommodates the communication unit 36 and the battery 38.

Specifically, as shown in FIG. 25, a guide line 154 serving as a reference for an imaging region and an imaging position is formed on the irradiation surface 152 to which the radiation 16 is irradiated in the main body 150a which is a large-volume housing. Has been. If the subject 14 (see FIG. 1) is positioned with respect to the radiation imaging apparatus 10A using the guide line 154 and the irradiation range of the radiation 16 is set, an appropriate radiographic image can be captured.

On the other hand, a handle 156 is provided on a side surface (a side surface distal to the main body 150a) of the expansion portion 150b which is a small-volume housing. A release button 158 for releasing the connection state between the main body 150a and the extension 150b is provided on the distal side surface. A display unit 160 capable of displaying various types of information is provided on the upper surface of the expansion unit 150b. Furthermore, a power switch 162 for activating the radiation imaging apparatus 10A and an input terminal 164 of an AC adapter capable of supplying power from the outside are provided on the distal side surface.

In addition, in the expansion unit 150b, a USB (Universal Serial Bus) cable is connected to one side surface connected to the main unit 150a, so that information can be transmitted / received to / from an external device such as the console 20 by wired communication. A USB terminal 166 is provided. On the other hand, in the expansion unit 150b, necessary information is recorded by loading the memory card 168 on the other side surface connected to the main body unit 150a, and after the information is recorded, the memory card 168 is taken out and loaded into an external device. Thus, a card slot 170 capable of transmitting / receiving information is provided.

FIG. 26 illustrates a state in which the main body 150a and the extension 150b are separated.

In the main body 150a, a recess 174 is formed on a side surface 172 facing the extension 150b. On the other hand, in the extension part 150b, a convex part 178 that can be fitted into the concave part 174 is formed on the side face 176 that faces the side face 172 of the main body part 150a.

The left and right wall portions in the recess 174 are provided with receiving

recesses

180 and 182, respectively. Locking

portions

184 and 186 that can be locked to the

housing recesses

180 and 182 are provided on the left and right side surfaces of the convex portion 178, respectively.

Further, a connector 188 is provided on the back side of the recess 174. On the other hand, the convex portion 178 is provided with a connector 190 that can be connected to the connector 188 when the concave portion 174 and the convex portion 178 are fitted.

Here, if the doctor or an engineer (hereinafter also referred to as a user 192) inserts the protrusion 178 into the recess 174 while holding the handle 156 in a state where the main body 150a and the extension 150b are separated, The

connectors

188 and 190 are connected, and the locking

portions

184 and 186 are locked in the

housing recesses

180 and 182, respectively. Thus, the main body 150a and the extension 150b are integrally connected and fixed, and the side surface 172 of the main body 150a and the side 176 of the extension 150b are in surface contact.

On the other hand, when the user 192 presses the release button 158, the locking

portions

184 and 186 are retracted toward the convex portion 178, and the locking state between the locking

portions

184 and 186 and the

housing recesses

180 and 182 is released. In this state, when the user 192 holds the handle 156 and pulls the expansion unit 150b toward the user 192, the expansion unit 150b is separated from the main body unit 150a. As a result, the fitting state between the concave portion 174 and the convex portion 178 and the connection state between the two

connectors

188 and 190 are released.

FIG. 27 illustrates the inside of the main body 150a and the additional part 150b by breaking a part of the upper surface (irradiation surface 152) of the main body part 150a and a part of the upper surface of the additional part 150b. FIG. 28 is a cross-sectional view of the main body 150a and the extension 150b.

A plate-like base 196 is disposed in the main body 150a. The base 196 is accommodated in the main body 150a by a fixing member (not shown). The radiation conversion panel 28 is interposed between the inner wall on the irradiation surface 152 side of the main body 150a and the upper surface of the base 196 (the surface on the irradiation surface 152 side). In this case, the second radiation conversion layer 28c, the switching filter 28b, and the first radiation conversion layer 28a are sequentially laminated from the upper surface of the base 196 toward the irradiation surface 152.

In the first modification, the switching filter 28b is not essential, and an arrangement structure in which the second radiation conversion layer 28c and the first radiation conversion layer 28a are stacked in this order may be employed. In any case, it is desirable that the first radiation conversion layer 28a is in surface contact with the inner wall on the irradiation surface 152 side.

The plane area of the base 196 is slightly larger than the plane area of the radiation conversion panel 28. The outer frame of the guide line 154 corresponds to the outline of the radiation conversion panel 28.

Here, as shown in FIG. 27, a plurality of flexible boards 198 to 204 are connected to each side surface of the radiation conversion panel 28 at a predetermined interval. In addition, the flexible substrates 198 to 204 are connected to different side surfaces of the radiation conversion panel 28.

Specifically, as shown in FIGS. 27 and 28, a plurality of flexible substrates 198 are connected to one side surface (the left side surface in FIG. 27) of the first radiation conversion layer 28a at a predetermined interval. A plurality of flexible substrates 202 are connected to the other side surface (the right side surface in FIG. 27) of the first radiation conversion layer 28a at a predetermined interval. Further, a plurality of flexible boards 204 are connected at a predetermined interval to one side surface of the switching filter 28b (a side surface distal to the additional portion 150b in FIG. 27 and a right side surface in FIG. 28). Furthermore, a plurality of flexible boards 200 are connected to one side surface of the second radiation conversion layer 28c (a side surface in the vicinity of the extension portion 150b in FIG. 27, a left side surface in FIG. 28) at a predetermined interval.

Insulating substrates 206a to 206c are disposed on the bottom surface of the base 196, and the driving circuit unit 30, the reading circuit unit 32, the cassette control unit 34, the filter control unit 40, and / or the voltage supply are provided on each of the insulating substrates 206a to 206c. Electronic components 208a to 208c that function as the unit 42 (see FIG. 1) are mounted.

Here, the

flexible substrates

198 and 202 are connected to the electronic component 208a, the flexible substrate 200 is connected to the electronic component 208c, and the flexible substrate 204 is connected to the electronic component 208b. Further, these electronic components 208a to 208c are connected to a connector 188 via a cable (not shown). Further, the connector 190 that can be connected to the connector 188 is connected to the communication unit 36 and the battery 38 via a cable (not shown).

Each flexible substrate 198 to 204 functions as a signal line for transmitting an electrical signal and a power supply line for supplying voltage and current. Therefore, the electronic component 208a is electrically connected to the first radiation conversion layer 28a via the

flexible substrates

198 and 202, and functions as a part of the drive circuit unit 30, the readout circuit unit 32, and the cassette control unit 34. The electronic component 208 b is electrically connected to the switching filter 28 b via the flexible substrate 204 and functions as the filter control unit 40 and the voltage supply unit 42. Further, the electronic component 208 c is electrically connected to the second radiation conversion layer 28 c via the flexible substrate 200 and functions as a part of the drive circuit unit 30, the readout circuit unit 32, and the cassette control unit 34.

When the main body 150a and the extension 150b are connected and fixed and the two

connectors

188 and 190 are connected, power is supplied from the battery 38 to the electronic components 208a to 208c through the two

connectors

188 and 190. It can be carried out. Since the power supply switch 162 is provided in the expansion unit 150b, the battery 38 starts or stops supplying power to the electronic components 208a to 208c each time the user 192 turns the power switch 162 on or off. Also good.

In addition, each of the electronic components 208a to 208c can send and receive signals to and from the communication unit 36 via the two

connectors

188 and 190. Therefore, the communication unit 36 transmits signals from the electronic components 208a to 208c to the console 20 by wireless communication, while information received from the console 20 is transmitted to the electronic components 208a to 208 via the two

connectors

188 and 190. 208c can be transmitted. Since the extension unit 150b is provided with a display unit 160, information from each electronic component 208a to 208c, information transmitted and received between the communication unit 36 and each electronic component 208a to 208c, Information transmitted and received between the console 36 and the console 20 can also be displayed on the display unit 160.

Furthermore, the expansion unit 150b is also provided with an input terminal 164, a USB terminal 166, and a card slot 170. Therefore, even in the portable radiation imaging apparatus 10 A, the battery 38 can be charged from the outside via the input terminal 164 or the USB terminal 166. In addition, when wireless communication by the communication unit 36 cannot be performed, wired communication via the USB terminal 166 is also possible. Further, when the wireless communication or the wired communication cannot be performed, the information from each of the electronic components 208 a to 208 c is stored in the memory card 168 loaded in the card slot 170, and the user 192 holds the memory card 168 to the console 20. You can carry it around.

The first radiation conversion layer 28a includes the a-Se semiconductor layer 74a (see FIGS. 3A to 10B, 20A, and 20B), as described with reference to FIGS. 1 to 24. Type radiation conversion layer. a-Se may deteriorate due to the progress of crystallization in a temperature higher than 30 ° C. Therefore, when adopting a radiation conversion layer containing a-Se, it is necessary to take a temperature control measure using some means, that is, a measure to keep the temperature of the semiconductor layer 74a below 30 ° C.

Therefore, in the radiation imaging apparatus 10A according to the first modification, the first radiation conversion layer 28a is in surface contact with the inner wall on the irradiation surface 152 side in the main body 150a. Further, if the main body 150a is connected to the extension 150b, the side surface 172 of the main body 150a and the side 176 of the extension 150b are in surface contact.

In this case, the portion on the irradiation surface 152 side in the main body 150a functions as a heat sink for the first radiation conversion layer 28a. As a result, the heat generated in the first radiation conversion layer 28a (the semiconductor layer 74a) is dissipated through the irradiation surface 152, and the temperature of the semiconductor layer 74a can be suppressed to less than 30 ° C.

In addition, if the extension part 150b is connected and fixed to the main body part 150a, the extension part 150b also functions as a heat sink for the first radiation conversion layer 28a. By connecting the expansion part 150b to the main body part 150a, the heat radiation area for the first radiation conversion layer 28a can be easily expanded. Thereby, the heat generated in the first radiation conversion layer 28a can be efficiently radiated through the irradiation surface 152 and the additional portion 150b, and the temperature of the semiconductor layer 74a can be effectively suppressed to less than 30 ° C.

Thus, by suppressing the temperature rise of the semiconductor layer 74a, it is possible to suppress the crystallization of a-Se.

Since the expansion unit 150b can be separated from the main body unit 150a, the following a-Se temperature management measures can be taken.

That is, in the case of order information in which the temperature rise of a-Se is predicted (for example, order information with a large number of shots or order information with a long shooting time), the user 192 connects the expansion unit 150b to the main body 150a. After fixing, radiation imaging of the subject 14 according to the order information may be performed using the radiation imaging apparatus 10A coupled and fixed.

On the other hand, when the order information is predicted not to exceed 30 ° C. (for example, order information with a small number of shots or order information with a short shooting time), the user 192 separates the extension unit 150b from the main body 150a. In this state, radiation imaging of the subject 14 according to the order information may be performed using the radiation imaging apparatus 10A including only the main body 150a. In this case, for example, a connector with a cable (not shown) and the connector 188 may be connected to supply power to the main body 150a from the outside, and to transmit and receive signals by wire communication with the outside.

By the way, as shown in FIG. 29, the

a-Si TFTs

82a and 82c and the a-Si photodiode 86c (see FIGS. 5A, 5B, 9A to 10B, 20A and 20B) exceed 40 ° C. As a result, the leakage current flowing out to the readout circuit section 32 via the

signal lines

66a and 66c (see FIG. 2) increases rapidly. Therefore, it is necessary to take the same temperature control measures as the a-Se semiconductor layer 74a, that is, to keep the temperature below 40 ° C. for the

a-Si TFTs

82a and 82c and the a-Si photodiode 86c.

In the first modified example, as described above, the portion on the irradiation surface 152 side of the main body 150a and the additional portion 150b function as a heat sink, and thus are generated in the

a-Si TFTs

82a and 82c and the a-Si photodiode 86c. The heat to be radiated can be radiated to the outside through the irradiation surface 152 and the extension part 150b. As a result, the temperature of the

a-Si TFTs

82a and 82c and the a-Si photodiode 86c can be suppressed to less than 40 ° C., and a sudden increase in leakage current can be prevented.

[Second Modification]
The radiographic apparatus 10B according to the second modification is also basically used as a portable electronic cassette, and as shown in FIGS. 30 to 32, a handle 156 is provided on one side surface of the casing 150, On the other side surface, a lid 210 that can be opened and closed is provided.

In addition to the display unit 160, the power switch 162, the input terminal 164, the USB terminal 166, and the card slot 170, the lid 210 is provided with an indicator 212 made up of LEDs or the like that display various conditions of the radiation imaging apparatus 10B. . Note that the indicator 212 may be omitted, and the display unit 160 may display various situations of the radiation imaging apparatus 10B. In addition, when the lid 210 is opened, the hollow portion 214 in the housing 150 communicates with the outside.

In the housing 150,

rails

220 and 222 extending linearly along the direction are formed on the two

side walls

216 and 218 along the direction from the lid 210 toward the handle 156, respectively.

In the hollow portion 214, the radiation conversion panel 28, the drive circuit unit 30, the readout circuit unit 32, the cassette control unit 34, the communication unit 36, and the battery are disposed below the

rails

220 and 222, as shown in FIG. 38, a radiation detection unit 224 that houses the filter control unit 40 and the voltage supply unit 42 (see FIG. 1) is disposed. In this case, the radiation conversion panel 28 is accommodated in a location near the irradiation surface 152 in the radiation detection unit 224.

A cable 228 with a connector 230 is connected to the side surface of the radiation detection unit 224 facing the lid 210. The connector 230 can be connected to a connector 232 provided on the lid 210. The connector 232 is electrically connected to the display unit 160, the power switch 162, the input terminal 164, the USB terminal 166, the card slot 170, and the indicator 212 provided on the lid 210. Therefore, when the two

connectors

230 and 232 are connected, the above-described units on the lid 210 side are electrically connected to the cassette control unit 34 and the like in the radiation detection unit 224 via the

connectors

230 and 232. become.

On the other hand, in the hollow portion 214, the heat radiation unit 226 is disposed at a position between the radiation detection unit 224 and the inner wall on the irradiation surface 152 side of the housing 150 so as to come into contact with the radiation detection unit 224 and the inner wall, respectively. Is arranged. As will be described later, the heat dissipation unit 226 needs to efficiently dissipate the heat generated by the radiation detection unit 224 (inside the radiation conversion panel 28), and thus is preferably made of a material having a high heat transfer coefficient. .

In addition, since the heat dissipation unit 226 is disposed in front of the radiation detection unit 224 along the incident direction of the radiation 16, the radiation unit 226 transmits the radiation 16 or is made of a material having a low absorption rate of the radiation 16. Is desirable. Further, side portions of the heat dissipating unit 226 facing the

rails

220 and 222 are formed as

step portions

234 and 236 corresponding to the shapes of the

rails

220 and 222, as shown in FIG.

Accordingly, the user 192 detects radiation from the lid 210 side along the

rails

220 and 222 and the inner wall on the bottom surface 238 side of the housing 150 with the lid 210 open and the hollow portion 214 communicating with the outside. When the unit 224 is inserted, the radiation detection unit 224 can be accommodated in the lower portion of the hollow portion 214. Further, when the user 192 inserts the heat radiation unit 226 from the lid 210 side along the

rails

220 and 222 and the inner wall on the irradiation surface 152 side of the housing 150, the heat radiation unit 226 is accommodated in the upper portion of the hollow portion 214. can do.

In the radiation imaging apparatus 10 B according to the second modification, the radiation conversion panel 28 is accommodated in the radiation detection unit 224 on the radiation unit 226 side, and the radiation unit 226 is an irradiation surface of the radiation detection unit 224 and the housing 150. It is in contact with the inner wall on the 152 side.

Therefore, the heat radiating unit 226 and the portion on the irradiation surface 152 side of the housing 150 function as a heat sink for the radiation conversion panel 28.

As a result, the heat generated in the semiconductor layer 74a (see FIGS. 3A to 10B, 20A, and 20B) of the first radiation conversion layer 28a constituting the radiation conversion panel 28 is transmitted through the heat dissipation unit 226 and the irradiation surface 152. It is possible to dissipate heat and suppress the temperature of the semiconductor layer 74a to less than 30 ° C.

The heat generated in the

a-Si TFTs

82a and 82c and the a-Si photodiode 86c is also dissipated through the heat dissipation unit 226 and the irradiation surface 152, so that the

a-Si TFTs

82a and 82c and the a-Si TFT The temperature of the photodiode 86c can be suppressed to less than 40 ° C., and a sudden increase in leakage current can be prevented.

[Third Modification]
As shown in FIGS. 33 and 34, the radiation imaging apparatus 10C according to the third modification has a heat circulation channel 240 formed in a relatively thick base 196 along the plane direction. Circulating fluid 252 circulates in 240. Therefore, the base 196 functions as a thermal circulation bus (thermal circulation part) as will be described later.

In this case, the electronic components 208a to 208c mounted on the insulating substrates 206a to 206c are fixed to the bottom surface of the base 196 via the adhesive layers 242a to 242c. An opening 244 that communicates with the outside is formed on the bottom surface 238 of the housing 150. A heat exchanger 246 including a Peltier element is fixed to a location facing the opening 244 on the bottom surface of the base 196.

The heat exchanger 246 is disposed between the inner wall on the bottom surface 238 side of the housing 150 and the bottom surface of the base 196 so as to block the communication state between the opening 244 and the hollow portion 214. The heat exchanger 246 includes, for example, a Peltier element in which a P-type semiconductor and an N-type semiconductor are joined by a plate-like electrode, and the plate-like electrode is disposed on the base 196 side. In this case, if the positive electrode of the DC power source is connected to the N-type semiconductor, the negative electrode is connected to the P-type semiconductor, and a DC current is passed from the N-type semiconductor to the P-type semiconductor through the plate electrode, the Peltier The element can absorb the heat of the circulating fluid 252 from the circulating fluid 252 flowing through the thermal circulation channel 240 through the base 196 and the plate-like electrode, and can radiate the heat to the outside through the opening 244.

On the other hand, if the positive electrode of the DC power source is connected to the P-type semiconductor, the negative electrode is connected to the N-type semiconductor, and a DC current is passed from the P-type semiconductor to the N-type semiconductor through the plate electrode, the Peltier element Can absorb the heat of the outside air through the opening 244, and can radiate the heat of the outside air to the circulating fluid 252 flowing through the thermal circulation channel 240 through the plate electrode and the base 196.

The cassette control unit 34 further includes a temperature detection unit 248 and a temperature control unit 250. When the

a-Si TFTs

82a and 82c (see FIGS. 5A, 5B, 9A to 10B, 20A, and 20B) are off, the temperature detection unit 248 has

signal lines

66a and 66c (see FIG. 2). The leakage current leaked to the readout circuit section 32 (see FIG. 1) via each of these is detected, and based on each detected leakage current, the a-Si TFT 82a (a-Se semiconductor layer 74a connected to) , And the temperatures of the a-Si TFT 82c and the a-Si photodiode 86c.

As described above, the plurality of pixels 62 are arranged in a matrix, and the

TFTs

82a and 82c of the pixels 62 for one column are connected to one

signal line

66a and 66c. Therefore, the temperature detection unit 248 estimates the a-Si temperature for each column (each block including a plurality of pixels 62). The temperature control unit 250 includes the above-described DC power supply, and based on the temperature estimated by the temperature detection unit 248, the temperature of the a-Se semiconductor layer 74a does not exceed 30 ° C. and falls within a temperature of about 25 ° C., and The heat exchanger 246 is controlled so that the

a-Si TFTs

82a and 82c and the a-Si photodiode 86c do not exceed 40 ° C. and fall within a predetermined temperature range (for example, 20 ° C. to 40 ° C.). To do.

The a-Se semiconductor layer 74a, the a-Si TFT 82a, the TFT 82c, and the a-Si photodiode are formed by the base 196, the heat circulation channel 240, the heat exchanger 246, the temperature detection unit 248, and the temperature control unit 250. A temperature control unit 247 for managing and controlling each temperature of 86c is configured. Thus, since the temperature control unit 247 has a relatively large configuration, the radiation imaging apparatus 10C is suitable for a built-in type electronic cassette. However, if the temperature control unit 247 can be reduced in size, the radiation imaging apparatus 10C can be applied as a portable electronic cassette.

Here, the temperature control unit 247 will be specifically described.

In the temperature control unit 247, the temperature control unit 250 supplies a direct current to the Peltier element of the heat exchanger 246 based on the temperature estimated by the temperature detection unit 248.

If the temperature of the a-Se semiconductor layer 74a exceeds 30 ° C., or the

a-Si TFTs

82a and 82c or the a-Si photodiode 86c may exceed 40 ° C., the Peltier element is removed from the circulating fluid 252. The heat of the circulating fluid 252 is absorbed through the base 196 and the plate electrode, and is radiated to the outside through the opening 244. That is, since the radiation conversion panel 28 is in surface contact with the base 196, the circulating fluid 252 flowing in the heat circulation channel 240 absorbs the heat generated in the radiation conversion panel 28 through the base 196, and heat The exchanger 246 absorbs the heat of the circulating fluid 252 and radiates the heat from the opening 244 to the outside.

As a result, the temperature of the a-Se semiconductor layer 74a can be suppressed to a temperature lower than 30 ° C. (for example, 25 ° C.) to prevent the deterioration of the a-Se. It is also possible to prevent the leakage current from rapidly increasing by suppressing the temperature of the

a-Si TFTs

82a and 82c or the a-Si photodiode 86c to a temperature lower than 40 ° C.

On the other hand, when there is a possibility that the temperature of the semiconductor layer 74a falls below a predetermined temperature range (temperature around 25 ° C.), or the temperature of the

TFTs

82a, 82c or the photodiode 86c is within a predetermined temperature range (20 ° C. to 40 ° C. The Peltier element absorbs the heat of the outside air through the opening 244 and dissipates heat to the circulating fluid 252 through the plate electrode and the base 196. As the circulating fluid 252 that has absorbed heat circulates in the thermal circulation channel 240, the radiation conversion panel 28 absorbs the heat of the circulating fluid 252 via the base 196, so that each of the above temperatures falls within a predetermined temperature range. Can fit.

Since the electronic components 208a to 208c are also fixed to the bottom surface of the base 196 via the adhesive layers 242a to 242c, the temperature control unit 247 is similar to the case of the semiconductor layer 74a. It is possible to take a temperature control measure so that .about.208c falls within a predetermined temperature range.

As described above, in the radiation imaging apparatus 10C according to the third modification, the base 196 functions as a thermal circulation bus, and therefore, for each column (each block) based on the temperature of the semiconductor layer 74a,

TFT

82a, 82c, or photodiode 86c. ) Can be controlled uniformly.

[Fourth Modification]
As shown in FIGS. 35 and 36, the radiation imaging apparatus 10D according to the fourth modification is a built-in type electronic cassette that is capable of performing standing imaging with respect to the subject 14 by being mounted on an imaging table 254.

In the photographing table 254, a hexahedral casing 260 is mounted on a support column 258 standing on a base 256 so as to be movable up and down. A guide wire 264 having the same function as the guide wire 154 is formed on the front surface of the casing 260. In addition, a loading case 268 in which the radiation imaging apparatus 10 D is mounted is loaded in the casing 260 from the side surface 266 of the casing 260.

Therefore, the subject 14 is positioned with respect to the guide line 264 while holding the handle 272 provided on the side surface 266. As a result, if the outer frame of the guide line 264 is set as the irradiation range of the radiation 16 and then the subject 14 is irradiated with the radiation 16 from the radiation output device 18, an appropriate radiation image can be taken. In FIG. 35, the case where the handle 272 is provided on the left side surface 266 of the casing 260 is illustrated, but it is needless to say that the handle 272 is also provided on the right side surface.

36, a longitudinal slot 274 is formed in the side surface 266 of the casing 260, and a loading case 268 can be loaded in the slot 274. The loading case 268 has a box shape that can accommodate the housing 150 of the radiation imaging apparatus 10 D, and a part of the side surface facing the slot 274 is formed as a notch 278. Further, a handle 270 to be held by the user 192 is provided on the side surface of the loading case 268 that is substantially flush with the side surface 266 when loaded.

The radiation imaging apparatus 10D corresponds to, for example, the main body 150a of the radiation imaging apparatus 10A of the first modified example, and a recess 174 and a connector 188 are provided at a position facing the notch 278. Yes. Therefore, if the block 284 provided at the distal end portion of the cable 282 is inserted into the recess 174 through the notch 278 in a state where the radiation imaging apparatus 10D is accommodated in the loading case 268, the cable 282 is provided in the block 284. The connector 286 electrically connected to the connector 188 and the connector 188 can be connected. Note that the cable 282 extends into the casing 260 via the slot 274.

As described above, in a state where the radiation imaging apparatus 10D is accommodated in the loading case 268 and the two

connectors

188 and 286 are connected, the user 192 holds the handle 270 and faces the notch 278 to the slot 274. When the loading case 268 is inserted into the slot 274, the loading case 268 and the radiation imaging apparatus 10D can be loaded into the casing 260. After loading into the casing 260, the subject 14 is positioned with respect to the guide wire 264.

In the above description, the case where the main body 150a in the first modification is the radiation imaging apparatus 10D has been described. However, the

radiation imaging apparatuses

10A and 10B (see FIGS. 25 to 32) may be configured without the handle 156. For example, the radiation imaging apparatus 10D can be housed in the loading case 268. Further, the radiation imaging apparatus 10C (see FIGS. 33 and 34) can be used as the radiation imaging apparatus 10D. That is, in the fourth modification, the

radiation imaging apparatuses

10A and 10B according to the first and second modifications are partially modified and used as the radiation imaging apparatus 10D, or the radiation imaging apparatus 10C is used as the radiation imaging apparatus 10D. By using it as it is, it can be used as a built-in type electronic cassette.

[Fifth Modification]
The radiation imaging apparatus 10E according to the fifth modification can be basically used by partially modifying the radiation imaging apparatuses 10A to 10D (see FIGS. 25 to 36) according to the first to fourth modifications. is there. However, in the fifth modification example, as shown in FIGS. 37 to 43, for example, when the radiation imaging apparatus 10E is loaded into the cradle 290 and charged after the imaging, the disinfecting liquid is injected to the radiation imaging apparatus 10E. By doing so, the radiation imaging apparatus 10E is different from the first to fourth modifications in that charging, disinfection and cooling are performed at once.

Therefore, in the radiation imaging apparatus 10E, the display unit 160, the power switch 162, the input terminal 164, the USB terminal 166, the card slot 170, the

connectors

188 and 190, the indicator 212, and the heat exchanger 246 are provided in the portion where the disinfectant is ejected. It is desirable not to provide such electrical parts or electronic parts.

37, a handle 288 is provided on one side surface of the housing 150 (upper side surface in FIG. 37).

On the other hand, as shown in FIGS. 37 to 39, the cradle 290 has a substantially U-shape when viewed from the side, and

upright portions

294 and 296 extend upward from both side portions of the base portion 292. As shown in FIGS. 37 and 38, the radiation imaging apparatus 10E is loaded between the two standing

portions

294 and 296. In this case, the upper end position of the standing portion 294 facing the irradiation surface 152 where the guide line 154 is formed is set higher than the upper end position of the standing portion 296 facing the bottom surface 238.

As shown in FIG. 39, both side portions of the standing

portions

294 and 296 are connected by connecting

portions

300 and 302, respectively. The upper end positions of the two connecting

portions

300 and 302 are set lower than the upper end positions of the two standing

portions

294 and 296. In addition, the connecting

portions

300 and 302 guide the radiation imaging apparatus 10E when loading the radiation imaging apparatus 10E from above the cradle 290, and after loading, guide grooves 304 for positioning and holding the

radiation imaging apparatus

10E, 306 is formed.

Accordingly, the user 192 (see FIG. 26) holds the handle 288, and the two standing

portions

294 and 296 in the plan view of FIG. And the radiographic apparatus 10E to the cradle 290 from above toward the base portion 292 so that both sides of the radiographic apparatus 10E are fitted in the

guide grooves

304 and 306 and fit in the two connecting

portions

300 and 302. Will be loaded.

That is, the space defined by the two standing

portions

294 and 296 and the two connecting

portions

300 and 302 becomes the accommodation space 298 of the radiation imaging apparatus 10E loaded in the cradle 290. Therefore, the charging process, the cooling process, and the disinfection process for the radiation imaging apparatus 10E are performed in a state where the radiation imaging apparatus 10E is loaded in the accommodation space 298.

Specifically, a plurality of nozzles 310 for injecting disinfectant liquid onto the irradiation surface 152 are two-dimensionally arranged on the side surface 308 of the standing portion 294 facing the irradiation surface 152. Further, a blower 312 for blowing air to the irradiation surface 152 is provided above the side surface 308.

On the other hand, on the side surface 314 facing the bottom surface 238 in the standing portion 296, a plurality of nozzles 316 for injecting a disinfecting liquid to the bottom surface 238 are two-dimensionally arranged. A blower 318 that blows air against the bottom surface 238 is provided above the side surface 314. A display unit 320 is provided on the outer surface of the standing unit 296 to display the operation state of the cradle 290, the state of the radiation imaging apparatus 10E, various information from the radiation imaging apparatus 10E, and the like.

It should be noted that the lower part of the radiation imaging apparatus 10E loaded in the cradle 290 (the side surface of the radiation imaging apparatus 10E facing the upper surface 326 of the base part 292) is provided at a location near the

coupling parts

300 and 302 on the upper surface 326 of the base part 292.

Support portions

322 and 324 to be supported are respectively provided. Therefore, when the radiation imaging apparatus 10E is loaded in the cradle 290, a slight gap is formed between the upper surface 326 of the base portion 292 and the lower part of the radiation imaging apparatus 10E.

FIG. 40 illustrates a schematic configuration of the cradle 290.

The cradle 290 includes a sensor 328, a communication unit 330, a power supply unit 332, a control unit 335, a power supply unit 336, a tank 338, a pump 340, and

fan motors

342 and 344 in addition to the display unit 320 described above.

The sensor 328 is, for example, an optical or ultrasonic sensor, emits a transmission wave (light, ultrasonic wave), and the radiation imaging apparatus 10E cradles based on a change in the reflected wave (light, ultrasonic wave). It is detected whether it is loaded in 290 or not. When the radiation imaging apparatus 10E is loaded in the cradle 290, the communication unit 330 transmits and receives signals by wireless communication with the communication unit 36 of the radiation imaging apparatus 10E.

When the radiation imaging apparatus 10E is loaded in the cradle 290, the power supply unit 332 performs non-contact power supply (non-contact power supply, power supply, charging) to the radiation imaging apparatus 10E. Specifically, the radiation imaging apparatus 10 E is provided with a power receiving unit 334 at a location facing the power supply unit 332. In a state where the radiation imaging apparatus 10E is loaded in the cradle 290 and the power supply unit 332 and the power reception unit 334 are opposed to each other, the power supply unit 332 receives power supply from the power supply unit 336 and supplies power to the power reception unit 334 without contact. To charge the battery 38.

Note that the non-contact power supply means a known non-contact power supply such as a microwave power supply method, an electromagnetic induction method, a resonance method, or a magnetic resonance method, and therefore, the details of these power supply methods are omitted. .

The control unit 335 is realized by a microcomputer and controls each unit in the cradle 290. Specifically, when a detection signal indicating that the radiation imaging apparatus 10E is loaded in the cradle 290 is input from the sensor 328, the control unit 335 performs wireless communication between the communication unit 330 and the communication unit 36. Transmission / reception of signals is permitted, and non-contact power feeding to the power reception unit 334 by the power supply unit 332 is permitted. On the other hand, when input of the detection signal from the sensor 328 is stopped, the control unit 335 prohibits wireless communication in the communication unit 330 and non-contact power supply in the power supply unit 332.

In the tank 338, a disinfectant containing alcohol is stored as a coolant. The pump 340 sends the cooling liquid to the

nozzles

310 and 316. The fan motor 342 ejects air from the blower 312 by rotating a fan (not shown). The fan motor 344 also blows air from the blower 318 by rotating a fan (not shown).

In the fifth modification, after radiation imaging or before radiation imaging, when the user 192 holds the handle 288 and loads the radiation imaging apparatus 10E into the cradle 290 from above, the sensor 328 loads the radiation imaging apparatus 10E. And the detection signal is output to the control unit 335.

The control unit 335 determines that the radiation imaging apparatus 10E is loaded in the cradle 290 by inputting the detection signal, and transmits / receives a signal to / from the communication unit 36 by the communication unit 330 and a power reception unit 334 by the power supply unit 332. Allow non-contact power feeding to. Further, the control unit 335 causes the display unit 320 to display information indicating that the radiation imaging apparatus 10E is loaded in the cradle 290. Thereby, the user 192 can recognize that the radiation imaging apparatus 10E is correctly loaded in the cradle 290.

The power supply unit 332 receives power supply from the power supply unit 336, performs non-contact power supply to the power reception unit 334, and charges the battery 38. In this case, since signals can be transmitted and received by wireless communication between the communication unit 36 and the communication unit 330, the charge amount of the battery 38 is transmitted from the communication unit 36 to the control unit 335 via the communication unit 330. . Therefore, the control unit 335 causes the display unit 320 to display information indicating that the battery 38 is being charged and the amount of charge of the battery 38. Thereby, the user 192 can grasp that the radiation imaging apparatus 10E (the battery 38 thereof) is being charged and the amount of charge thereof.

In addition, the control unit 335 drives the pump 340 to send the disinfecting liquid stored in the tank 338 to the

nozzles

310 and 316. As a result, as shown in FIG. 41,

disinfectants

346 and 348 are sprayed from the

respective nozzles

310 and 316 onto the respective surfaces including the irradiation surface 152 and the bottom surface 238 of the radiation imaging apparatus 10E. The radiation imaging apparatus 10 E can be cooled by spraying the disinfecting

liquids

346 and 348 by the temperature of the disinfecting

liquids

346 and 348 themselves and the heat absorption when the disinfecting

liquids

346 and 348 are vaporized.

As described above, the upper end position of the standing portion 294 facing the irradiation surface 152 is higher than the upper end position of the standing portion 296 facing the bottom surface 238, and the standing portion 294 covers the irradiation surface 152. It is arranged. In addition, a plurality of nozzles 310 are two-dimensionally arranged on the side surface 308 of the standing portion 294. Therefore, each nozzle 310 sprays the disinfectant 346 so as to cover the irradiation surface 152 as a whole.

At the time of photographing, the subject 14 is positioned on the irradiation surface 152 side, so that the irradiation surface 152 can be efficiently sterilized by spraying the disinfecting liquid 346 on the entire irradiation surface 152. In addition, since the radiation conversion panel 28 is disposed near the irradiation surface 152 in the radiation imaging apparatus 10E, if the disinfecting liquid 346 is sprayed on the entire irradiation surface 152, the radiation conversion panel 28 is effectively cooled. can do.

Note that the ejection time of the disinfecting

liquids

346 and 348 from the

nozzles

310 and 316 may be a predetermined fixed time. Alternatively, as described below, the injection of the disinfecting

liquids

346 and 348 may be stopped when the temperature on the radiation imaging apparatus 10E side is lowered to a predetermined temperature after the injection of the disinfecting

liquids

346 and 348 is started.

As described in the third modification, the temperature detection unit 248 (see FIG. 34) of the cassette control unit 34 performs the a-Si TFT 82a (the a-Se semiconductor layer 74a connected thereto) based on the leakage current. , And temperatures of the a-Si TFT 82c and the a-Si photodiode 86c can be estimated.

Therefore, the temperature detection unit 248 may sequentially execute estimation processing of each temperature based on the leakage current, and transmit the estimation result as temperature information from the communication unit 36 to the communication unit 330 by wireless communication. Thereby, the control unit 335 sequentially acquires the temperature information received by the communication unit 330, and the temperature indicated by the acquired temperature information is reduced to a predetermined temperature (a-Si: 40 ° C. or less, a-Se: 30 ° C. or less). At that time, the drive of the pump 340 is stopped. Thereby, the cooling process and the disinfection process for the radiation imaging apparatus 10E can be performed efficiently.

After stopping the pump 340 from stopping the injection of the disinfecting

liquids

346 and 348 from the

nozzles

310 and 316, the control unit 335 drives the fan motor 342 and blows out the air 349 from the blower 312 as shown in FIG. Let As described above, a slight gap is formed between the lower portion of the radiation imaging apparatus 10E and the upper surface 326 of the base portion 292. Therefore, the air 349 blown out from the blower 312 reaches downward along the irradiation surface 152 and the side surface 308 and flows upward along the bottom surface 238 and the side surface 314 from the gap. Accordingly, the air 349 blown out from the blower 312 circulates around the radiation imaging apparatus 10E, and as a result, vaporization of the disinfecting

liquids

346 and 348 attached to the radiation imaging apparatus 10E can be accelerated.

Note that the blow time of the air 349 from the blower 312 may be a predetermined fixed time, or, as described above, when the temperature indicated by the temperature information from the temperature detector 248 decreases to a predetermined temperature. The blowing of air 349 from the blower 312 may be stopped.

In this way, after the cooling process and the disinfection process for the radiation imaging apparatus 10E are completed, the user 192 takes out the radiation imaging apparatus 10E from the cradle 290 by holding the handle 288 and pulling the radiation imaging apparatus 10E upward. . In this case, the control unit 335 drives the

fan motors

342 and 344 to blow out the

air

349 and 350 from the

blowers

312 and 318 as shown in FIG. 43, thereby remaining attached to the radiation imaging apparatus 10E. The

disinfectants

346 and 348 may be blown off.

In addition, since the charge amount of the battery 38 is sequentially displayed on the display unit 320, after confirming that the cooling process and the disinfection process for the radiation imaging apparatus 10E are completed and the battery 38 is fully charged. The user 192 may hold the handle 288 and pull up the radiation imaging apparatus 10E.

As described above, in the fifth modification, the above-described charging process, cooling process, and disinfection process are performed at a time with the radiation imaging apparatus 10E loaded in the cradle 290, so that the radiation imaging apparatus 10E can be cooled in a short time. it can. Further, if the charging of the battery 38 is completed and the cooling process and the disinfection process for the radiation imaging apparatus 10E are also completed, the charged radiation imaging apparatus 10E can be used for the next imaging as it is.

In the above description, the case where the charging process, the cooling process, and the disinfection process for the radiation imaging apparatus 10E are performed all at once after imaging or before imaging is described. However, the temperature detected by the temperature detection unit 248 is within a predetermined range. (When a certain temperature is reached), the radiographic apparatus 10E is immediately loaded into the cradle 290, and charging, cooling and disinfection are performed, thereby reducing a-Se degradation and rapid increase in leakage current. It can also be suppressed.

[Sixth Modification]
In the radiation imaging apparatus 10F according to the sixth modification, as shown in FIG. 44, the first radiation conversion layer 28a is formed in a structure that suppresses crystallization of a-Se in the semiconductor layer 74a. This is different from the present embodiment and the first to fifth modifications.

Specifically, a crystallization suppression layer 352 is formed on the pixel electrode 76a and the planarization film 84a. The crystallization suppression layer 352 is made of a-Se containing arsenic (As) of 10 atomic% or more and 40 atomic% or less, has excellent heat resistance, and functions as a charge injection layer. Further, the crystallization suppressing layer 352 cooperates with the electric field relaxation layer 354 described later to absorb the uneven shape formed by the pixel electrode 76a and the planarization film 84a, and a-Se crystallization in the semiconductor layer 74a. And the crystallization of a-Se in the electric field relaxation layer 354 is also suppressed.

Between the crystallization suppression layer 352 and the semiconductor layer 74a, an electric field relaxation layer 354 and a first thermal characteristic enhancement layer 356 are sequentially stacked. The electric field relaxation layer 354 is made of a-Se containing As and lithium fluoride, and the lithium fluoride captures holes to reduce the electric field and prevent the holes from being injected into the semiconductor layer 74a. To do. Further, the electric field relaxation layer 354 covers the crystallization suppressing layer 352 so as to flatten the surface. Note that the electric field relaxation layer 354 preferably contains 0.5 atomic% or more and 5 atomic% or less As, and preferably contains 0.02 wt% or more and 5 wt% or less lithium fluoride.

The first thermal characteristic enhancement layer 356 is made of a-Se containing As and suppresses thermal diffusion of lithium fluoride from the electric field relaxation layer 354 to the semiconductor layer 74a. In addition, it is preferable that the 1st thermal characteristic reinforcement | strengthening layer 356 contains 10 atomic% or more and 40 atomic% or less As.

On the other hand, a second thermal characteristic enhancement layer 358 and an electron injection blocking layer 360 are sequentially stacked between the semiconductor layer 74a and the common electrode 78a.

The second thermal property enhancement layer 358 is made of a-Se containing As. The second thermal characteristic enhancement layer 358 has excellent heat resistance and covers the stacked body from the crystallization suppressing layer 352 to the semiconductor layer 74a, thereby suppressing crystallization of the semiconductor layer 74a and the electric field relaxation layer 354.

The electron injection blocking layer 360 includes a first electron injection blocking layer 360a and a second electron injection blocking layer 360b. The first electron injection blocking layer 360a is an a-Se layer containing 5 atomic% or less As, and the second electron injection blocking layer 360b is a layer made of antimony trisulfide. The electron injection blocking layer 360 blocks the injection of electrons from the common electrode 78a to the semiconductor layer 74a.

In the sixth modification, since the first radiation conversion layer 28a has the above-described structure, the electric field relaxation layer 354 captures holes from the pixel electrode 76a by lithium fluoride and injects holes into the semiconductor layer 74a. It can be suppressed. Thereby, an increase in dark current can be suppressed. In addition, since the electric field relaxation layer 354 contains As, the heat resistance is improved, the action of lithium fluoride, ie, suppression of hole injection into the semiconductor layer 74a, can be maintained, and an increase in dark current can be suppressed. .

Further, since the electric field relaxation layer 354 covers the crystallization suppressing layer 352 and flattens the surface, the concavo-convex shape of the pixel electrode 76a and the flattening film 84a causes crystallization of a-Se and deformation of each layer on the semiconductor layer 74a. Etc. can be suppressed. As a result, the semiconductor layer 74a can be made uniform as a whole and a uniform electric field can be applied.

Furthermore, by providing the first thermal characteristic enhancement layer 356 and the crystallization suppression layer 352, the thermal diffusion of lithium fluoride in the electric field relaxation layer 354 to the semiconductor layer 74a can be effectively suppressed. Thereby, an increase in dark current accompanying thermal diffusion of lithium fluoride to the semiconductor layer 74a can be suppressed. Further, by suppressing an increase in dark current, a high voltage can be applied to the semiconductor layer 74a, and various characteristics of the radiation imaging apparatus 10F including sensitivity characteristics can be improved.

Moreover, in the radiation imaging apparatus 10F, as described above, since heat resistance is improved, handling such as temperature management is easy.

Furthermore, since the atomic concentration of As contained in the crystallization suppression layer 352 and the first thermal characteristic enhancement layer 356 is higher than the atomic concentration of As contained in the electric field relaxation layer 354, radiography is performed while maintaining the electric field relaxation effect. Deterioration of heat resistance of the device 10F can be suppressed, and dark current can be effectively suppressed.

Furthermore, by providing the second thermal property enhancement layer 358, the heat resistance of the entire first radiation conversion layer 28a is improved, and the function of the electric field relaxation layer 354 is more effectively achieved together with the first thermal property enhancement layer 356. The hole can be effectively prevented from being injected into the semiconductor layer 74a.

In addition, since the crystallization suppression layer 352 and the electric field relaxation layer 354 are provided, the crystallization suppression layer 352 cooperates with the electric field relaxation layer 354 to absorb the uneven shape of the pixel electrode 76a and the planarization film 84a, thereby forming a semiconductor layer. While suppressing the crystallization of 74a, the crystallization of the electric field relaxation layer 354 can be suppressed, and the improved heat resistance can be stably maintained.

Further, if the film thickness of the crystallization suppressing layer 352 is made larger than the film thickness of the first thermal characteristic enhancement layer 356, the semiconductor layer 74a absorbs the above uneven shape sufficiently in cooperation with the electric field relaxation layer 354. The crystallization of the electric field relaxation layer 354 can be sufficiently suppressed.

[Other variations]
In the above description, the case where the semiconductor layer 74a is a-Se has been described.

In the present embodiment and each of the above-described modifications, an a-Si or crystalline silicon (c-Si) semiconductor layer 74a may be used instead of the a-Se semiconductor layer 74a.

A-Si and c-Si have a lower K edge than various materials constituting a scintillator and a-Se, and easily absorb lower energy components. That is, the K edge of a-Se is 12.7 keV, whereas the K edge of a-Si is 1.7 keV, and the K edge of c-Si is 1.1 keV.

Therefore, the

radiographic apparatuses

10 and 10A to 10F using the a-Si or c-Si semiconductor layer 74a are suitable for radiographing a mammo of the subject 14 for which radiography with a lower energy component is desired. is there.

The a-Se semiconductor layer 74a can convert the light 102 in the blue wavelength region from the second radiation conversion layer 28c into

charges

94c and 96c. Therefore, as the scintillator of the second radiation detector 72c combined with the a-Se semiconductor layer 74a, a scintillator made of a phosphor that generates light 102 in the blue wavelength region must be selected. That is, when the semiconductor layer 74a is made of a-Se, the scintillator options are limited.

On the other hand, when the semiconductor layer 74a is made of a-Si or c-Si, the entire visible light region is a sensitivity wavelength region. Therefore, a scintillator using a phosphor that generates light 102 in the visible light region is used. If so, it can be selected as a scintillator that can be combined with the a-Si or c-Si semiconductor layer 74a. That is, when the a-Si or c-Si semiconductor layer 74a is used, the number of scintillator options can be greatly increased.

In the present embodiment and each of the above-described modifications, the semiconductor layer 74a made of CdTe having a K edge of 30 keV may be used. As shown in FIG. 22, all the materials constituting the scintillator have a higher K edge than CdTe. For example, the K edge of CsI is about 35 keV. The band gap of CdTe is 1.44 eV and has sensitivity in the visible light region.

Therefore, as the CdTe semiconductor layer 74a, a phosphor that emits light 102 in the visible light region can be selected as a scintillator, like the a-Si or c-Si semiconductor layer 74a. Accordingly, even in this case, the number of scintillator options can be increased.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention.

Claims

In the radiation imaging apparatus (10, 10A-10F) in which the two radiation conversion layers (28a, 28c) are laminated along the incident direction of the radiation (16),
One radiation conversion layer (28a) includes a first radiation detection section (72a) that directly converts the radiation (16) into charges (94a, 96a), and charges from the first radiation detection section (72a). (94a, 94c, 96a, 96c) a first radiation detection layer of a direct conversion type having a first charge detection unit (70a) for taking out (94a, 94c, 96a, 96c),
The other radiation conversion layer (28c) includes a second radiation detector (72c) that converts the radiation (16) into fluorescence (98, 102, 104, 140), and the fluorescence (98, 104, 140). An indirect conversion type second radiation conversion layer having a second charge detection unit (70c) for converting into a charge,
The first radiation detection unit (72a) charges the fluorescence (102) with a charge (94c) when the fluorescence (102) converted from the radiation (16) by the second radiation detection unit (72c) is incident. , 96c).
The apparatus (10, 10A-10F) according to claim 1,
Along the incident direction of the radiation (16), the first radiation conversion layer (28a) and the second radiation conversion layer (28c) are sequentially laminated,
The first radiation detection unit (72a) includes a semiconductor layer (74a) that directly converts the radiation (16) into electric charges (94a, 96a),
The radiation imaging apparatus, wherein the second radiation detection unit (72c) is a scintillator that converts the radiation (16) into the fluorescence (98, 102, 104, 140).
The apparatus (10, 10A-10F) according to claim 2,
The radiographic apparatus according to claim 1, wherein the semiconductor layer (74a) is made of selenium, silicon or CdTe.
The apparatus (10, 10A-10F) according to claim 3,
The scintillator absorbs a higher energy component of the radiation (16) than the selenium, the silicon, or the CdTe.
The apparatus (10, 10A-10F) according to claim 3 or 4,
The radiographic apparatus according to claim 1, wherein the scintillator generates fluorescence (102) in at least a blue wavelength region.
The device (10, 10A-10F) according to any one of claims 2 to 5,
The scintillator is made of CsI: Na, CaWO 4 , YTaO 4 : Nb, BaFX: Eu (X is Br or Cl), or LaOBr: Tm.
The device (10, 10A-10F) according to any one of claims 2 to 6,
The scintillator includes a first fluorescent material that generates fluorescence (102) in a wavelength region that can be converted into charges (94c, 96c) in the semiconductor layer (74a), and charges in the second charge detection unit (70c). And a second fluorescent material that generates fluorescence (98, 104, 140) in a wavelength region that can be converted into a radiation image.
The device (10, 10A-10F) according to any one of claims 2 to 7,
The first radiation detector (72a) includes the semiconductor layer (74a) and a plurality of pixel electrodes (76a) formed on one surface of the semiconductor layer (74a) along the incident direction of the radiation (16). A common electrode (78a) formed entirely on the other surface of the semiconductor layer (74a),
By applying a voltage between each of the pixel electrodes (76a) and the common electrode (78a), charges (94a, 94c, 96a, 96c) generated in the semiconductor layer (74a) are transferred to the pixel electrodes. The radiation imaging apparatus, wherein the first charge detection unit (70a) takes out via (76a).
The apparatus (10, 10A-10F) according to claim 8,
When the first radiation detector (72a) and the first charge detector (70a) are stacked along the incident direction of the radiation (16), the pixel electrodes (76a) The common electrode (78a) is formed on the first charge detection unit (70a) side of the semiconductor layer (74a) and is formed on the first charge detection unit (70a) side of the semiconductor layer (74a). Is formed on the opposite side of the radiation imaging apparatus.
The apparatus (10, 10A-10F) according to claim 9,
When the common electrode (78a) is formed on the second radiation conversion layer (28c) side of the semiconductor layer (74a), the common electrode (78a) is transparent to transmit the fluorescence (102). A radiation imaging apparatus characterized by being an electrode.
The apparatus (10, 10A-10F) according to claim 9,
When the common electrode (78a) is formed on the second radiation conversion layer (28c) side of the semiconductor layer (74a), the common electrode (78a) is an optical that can transmit the fluorescence (102). A radiographic apparatus characterized by being a filter.
The device (10, 10A-10F) according to any one of claims 1 to 10,
It further includes an optical filter (28b) interposed between the first radiation conversion layer (28a) and the second radiation conversion layer (28c) and capable of transmitting the fluorescence (102). Radiography equipment.
Device (10, 10A-10F) according to claim 11 or 12,
The optical filter (28b, 78a) includes light (102) in a wavelength region that can be converted into electric charges (94c, 96c) by the first radiation detection unit (72a) out of the fluorescence (98). A radiation imaging apparatus characterized by being a dichroic filter that transmits the light (104) outside the wavelength region to the second radiation conversion layer (28c) side while transmitting to the radiation conversion layer (28a) side.
The apparatus (10, 10A-10F) according to any one of claims 1 to 13,
The second charge detection unit (70c) includes a photodiode (86c) or an organic photoconductor (144c) that converts the fluorescence (98, 104, 140) into a charge, and is configured to perform radiography. apparatus.
The device (10, 10A-10F) according to claim 14,
When the second charge detector (70c) and the second radiation detector (72c) are sequentially stacked on the first radiation conversion layer (28a), the organic photoconductor (144c) ) Of the fluorescence (98), the light (102) in a wavelength region that can be converted into electric charges (94c, 96c) by the first radiation detection unit (72a) is converted into the first radiation conversion layer (28a). A radiation imaging apparatus characterized by being capable of absorbing light (98, 104, 140) outside the wavelength region while being transmitted to the side.
The device (10, 10A-10F) according to any one of claims 1 to 15,
The first charge detector (70a) outputs a first radiation image corresponding to the charges (94a, 94c, 96a, 96c) taken out from the first radiation detector (72a),
The second charge detector (70c) outputs a second radiation image corresponding to the charges converted from the fluorescence (98, 104, 140),
Control unit (34) provided in the radiation imaging apparatus (10, 10A-10F) and controlling the first radiation conversion layer (28a) and the second radiation conversion layer (28c), or external image processing The apparatus (20) adds the first radiographic image and the second radiographic image to obtain a desired image, and the radiographic imaging device.