JP2013002881A - Radiation image detector and radiographic imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation image detector and a radiographic imaging device, allowing an excellent energy subtraction image to be obtained.SOLUTION: A radiation image detector 3 comprises: a sensor panel 30 having a base plate 40 with a property to absorb light in a first wavelength region, and an array of first picture elements 41 and an array of second picture elements 42 arranged on the base plate 40; a first fluorescent material 31 which emits fluorescent light including the light in the first wavelength region by exposure to radiation in a first energy region; and a second fluorescent material 32 which is arranged opposite to the first fluorescent material across the sensor panel and emits fluorescent light by exposure to radiation in a second energy region. The first picture elements substantially have spectral sensitivity only in the first wavelength region. The array of the first picture elements is arranged on the first fluorescent material side of the base plate, so as to detect the fluorescent light from the first fluorescent material. The array of the second picture elements detects the fluorescent light from the second fluorescent material.

Description

  The present invention relates to a radiation image detection device and a radiation imaging apparatus including the radiation image detection device.

  In recent years, a radiological image detection apparatus that detects a radiographic image and generates digital image data has been put into practical use, and is rapidly spreading for the reason that an image can be immediately confirmed as compared with a conventional imaging plate. There are various types of radiological image detection apparatuses, and one of them is an indirect conversion type.

  An indirect conversion type radiological image detection apparatus includes a scintillator (phosphor) formed of a fluorescent composition that emits fluorescence by radiation exposure, and an array of pixels that detect the fluorescence generated in the scintillator and convert it into an electrical signal on a substrate. And a provided sensor panel. The radiation transmitted through the subject is converted into light by the scintillator, and the fluorescence of the scintillator is converted into an electrical signal by the pixel of the sensor panel, thereby generating image data.

  Then, image data based on a low energy component of radiation and image data based on a high energy component are acquired, and an image in which a specific structure of a subject (for example, a patient's organ, bone, or blood vessel) is emphasized is obtained. An indirect conversion type radiological image detection apparatus for performing so-called energy subtraction is known (see, for example, Patent Document 1).

  The radiological image detection apparatus described in Patent Document 1 includes a sensor panel in which an array of pixels is provided on both sides of a substrate, and two scintillators arranged to face each other with the sensor panel interposed therebetween. ing. The low energy component of the radiation transmitted through the subject is absorbed by one scintillator arranged on the radiation incident side, and the fluorescence generated in this scintillator is detected by an array of pixels provided on the substrate surface facing this scintillator. Image data based on the low energy component is acquired. The high energy component of radiation passes through the incident side scintillator and the sensor panel and is absorbed by the other scintillator, and the fluorescence generated in this scintillator is an array of pixels provided on the substrate surface facing the scintillator. And image data based on the high energy component is acquired.

JP-A-7-27865

  A glass substrate is typically used as the substrate of the sensor panel. As in the radiological image detection apparatus described in Patent Document 1, in the radiological image detection apparatus configured by sandwiching the sensor panel between two scintillators, the sensor panel substrate is a transparent substrate such as a glass substrate. A part of the fluorescence generated in one scintillator may pass through the substrate without being absorbed by the array of pixels corresponding to the scintillator, and may enter the other array of pixels. Thereby, the contamination of the fluorescence of two scintillators arises and the degradation of an energy subtraction image is caused.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a radiological image detection apparatus and a radiographic apparatus that can obtain a good energy subtraction image.

(1) a sensor panel having a substrate having absorption characteristics with respect to light in the first wavelength band, and an array of first pixels and an array of second pixels provided on the substrate, and a first energy A first phosphor that emits fluorescence including the first wavelength region by being exposed to radiation in a region, a second energy that is disposed opposite the first phosphor across the sensor panel A second phosphor that emits fluorescence when exposed to radiation in the region, wherein the first pixel has spectral sensitivity substantially only in the first wavelength region, the array comprising: Radiation image detection that is provided on the first phosphor side of the substrate and detects fluorescence generated in the first phosphor, and the second pixel array detects fluorescence generated in the second phosphor. apparatus.
(2) a sensor panel having a substrate having an absorption characteristic for light in the first wavelength band, and an array of first pixels and an array of second pixels provided on the substrate, and a first energy A first phosphor that emits fluorescence contained in the first wavelength range by being exposed to radiation in a region, and is disposed opposite to the first phosphor across the sensor panel; A second phosphor that emits fluorescence when exposed to radiation in an energy range, and the first pixel array is provided on the first phosphor side of the substrate, and the first fluorescence A radiographic image detection apparatus that detects fluorescence generated in a body, and the second pixel array is provided on the second phosphor side of the substrate to detect fluorescence generated in the second phosphor.
(3) The radiographic image detection apparatus according to (1) or (2), the first image data acquired by the first pixel array, and the second image data acquired by the second pixel array. A radiation imaging apparatus comprising: an image processing unit that generates an energy subtraction image using image data.

  According to the radiological image detection apparatus of (1), the fluorescence generated in the second phosphor is included in the first wavelength range, or the component in the first wavelength range is included in the fluorescence generated in the second phosphor. They are absorbed by the substrate. Thus, fluorescence contamination is prevented and the image acquired by the first array of pixels depends only on the component of the first energy region of the radiation incident on the radiation image detection device. According to the radiation image detection apparatus of (2) above, even if a part of the fluorescence generated in the first phosphor passes through the first pixel array, they are absorbed by the substrate. Thus, the current population of fluorescence is prevented and the image acquired by the second pixel array depends only on the component of the second energy region of the radiation incident on the radiation image detection device. As described above, a good energy subtraction image can be obtained.

It is a figure which shows typically the structure of an example of the radiographic image detection apparatus and radiography apparatus for describing embodiment of this invention. It is a control block diagram of the radiography apparatus of FIG. It is a figure which shows typically the structure of the radiographic image detection apparatus of FIG. It is a figure which shows typically the structure of the modification of the radiographic image detection apparatus of FIG. It is a figure which shows typically the structure of the other modification of the radiographic image detection apparatus of FIG. It is a figure which shows typically the structure of the other example of the radiographic image detection apparatus for describing embodiment of this invention. It is a figure which shows typically the structure of the modification of the radiographic image detection apparatus of FIG. It is a figure which shows typically the structure of the modification of the radiographic image detection apparatus of FIG. It is a figure which shows typically the structure of the other example of the radiographic image detection apparatus for describing embodiment of this invention. It is a figure which shows typically the structure of the modification of the radiographic image detection apparatus of FIG. It is a figure which shows typically the structure of the modification of the radiographic image detection apparatus of FIG.

  FIG. 1 shows a configuration of an example of a radiation image detection apparatus and a radiation imaging apparatus for explaining an embodiment of the present invention, and FIG. 2 shows a control block of the radiation imaging apparatus of FIG.

  An X-ray imaging apparatus 1 shown in FIG. 1 is an X-ray diagnostic apparatus that images a subject (patient) H in a standing position, and includes an X-ray source 2 that emits cone beam X-rays to the subject H, and an X-ray source. 2, an X-ray image detection device 3 that detects X-rays transmitted through the subject H from the X-ray source 2 and generates image data, and an exposure operation of the X-ray source 2 based on the operation of the operator And the console 4 that controls the imaging operation of the X-ray image detection apparatus 3 and processes the image data acquired by the X-ray image detection apparatus 3. The X-ray source 2 is held by an X-ray source holding device 5 suspended from the ceiling. The X-ray image detection apparatus 3 is held by a stand 6 installed on the floor.

  The X-ray source 2 is emitted from the X-ray tube 12 and the X-ray tube 12 that generates X-rays according to the high voltage applied from the high voltage generator 11 based on the control of the X-ray source control unit 10. The X-ray includes a collimator unit 14 having a movable collimator 13 that limits an irradiation field so as to shield a portion that does not contribute to the inspection area of the subject H.

  The X-ray source holding device 5 is connected to a carriage unit 16 configured to be movable in a horizontal direction (z direction) along a ceiling rail 15 installed on the ceiling, and extends downward from the carriage unit 16. A plurality of support columns 17, a drive mechanism for moving the carriage unit 16 along the ceiling rail, and a drive mechanism for expanding and contracting the support columns 17 are provided. The X-ray source 2 is attached to the distal end portion of the column portion 17. When the X-ray source holding device 5 moves along the ceiling rail 15, the distance SID in the horizontal direction between the X-ray source 2 and the X-ray image detection device 3 is changed, and the support column 17 expands and contracts. As a result, the position of the X-ray source 2 in the vertical direction is changed. Both drive mechanisms are controlled by the console 4 based on an operator's setting operation.

  The stand 6 includes a main body 18 installed on the floor, a holding portion 19 attached to the main body 18 so as to be movable in the vertical direction, and a drive mechanism for moving the holding portion 19 up and down. The X-ray image detection device 3 is attached to the holding unit 19. The drive mechanism is controlled by the control device 20 of the console 4 described later based on the setting operation by the operator.

The console 4 is provided with a control device 20 including a CPU, a ROM, a RAM, and the like.
The control device 20 includes an input device 21 through which an operator inputs an imaging instruction and the content of the instruction, and an image processing unit 22 that processes the image data acquired by the X-ray image detection device 3 to generate an X-ray image. , An image storage unit 23 for storing X-ray images, a monitor 24 for displaying X-ray images and the like, and an interface (I / F) 25 connected to each unit of the X-ray imaging apparatus 1. The control device 20, input device 21, image processing unit 22, image storage unit 23, monitor 24, and I / F 25 are connected via a bus 26.

  By operating the input device 21, the distance between the X-ray source 2 and the X-ray image detection device 3 (imaging distance) SID, X-ray imaging conditions such as tube voltage, imaging timing, and the like are input. Based on the horizontal position of the X-ray source 2 supplied from the X-ray source holding device 5, the control device 20 moves the X-ray source 2 to a position corresponding to the input imaging distance SID. The radiation source holding device 5 is driven. Further, the control device 20 moves the X-ray source 2 to the vertical position facing the X-ray image detection device 3 based on the vertical position of the X-ray image detection device 3 supplied from the stand 6. The radiation source holding device 5 is driven.

  The X-ray image detection device 3 includes a sensor panel 30, a first scintillator 31 and a second scintillator 32 that are formed of a fluorescent composition that emits fluorescence by X-ray exposure and is disposed so as to sandwich the sensor panel therebetween. It has.

  The X-ray image detection apparatus 3 is attached to the holding unit 19 (see FIG. 1) so that the first scintillator 31 is located on the X-ray source 2 side. The light enters the line image detection device 3. X-rays incident on the X-ray image detection device 3 (hereinafter referred to as incident X-rays) first enter the first scintillator 31, and the low energy component is absorbed by the first scintillator 31. On the other hand, the high energy component of incident X-rays is transmitted through the first scintillator 31 and the sensor panel 30 to enter the second scintillator 32 and is absorbed by the second scintillator 32.

  Fluorescence is generated in each of the first scintillator 31 that absorbs the low energy component of the incident X-ray and the second scintillator 32 that absorbs the high energy component, and the fluorescence is individually detected by the sensor panel 30 and is low. Two pieces of image data are generated: image data based on energy components and image data based on high energy components. These image data are sent from the sensor panel 30 to the image processing unit 22 (see FIG. 2) of the console 4, and the image processing unit 22 weights both image data appropriately, for example, from one image data to the other. An energy subtraction image is generated by subtracting the image data.

  FIG. 3 shows the configuration of the X-ray image detection apparatus 3.

  First, the sensor panel 30 of the X-ray image detection apparatus 3 will be described.

  The sensor panel 30 includes a substrate 40, and an array of first pixels 41 and an array of second pixels 42 provided on the substrate 40.

  The substrate 40 is made of a semiconductor material having a band gap of 2.8 eV or more, and has an absorption characteristic for light in a blue (380 nm to 495 nm) wavelength region. Examples of such semiconductor materials include SiC (band gap: 2.8 eV), ZnO (band gap: 3.2 eV), GaN (band gap: 3.4 eV), and the like.

  The array of the first pixels 41 is provided on the surface of the semiconductor substrate 40 that faces the first scintillator 31. Each of the first pixels 41 receives a fluorescence emitted from the first scintillator 31 and generates a charge, and a photoelectric conversion element 43 such as a photodiode, and reads out the charge generated in the photoelectric conversion element 43. It is composed of a readout circuit section 44 such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). Both the photoelectric conversion element 43 and the readout circuit section 44 are formed on the conductor substrate 40. Thus, the photoelectric conversion element 43 formed on the semiconductor substrate 40 having absorption characteristics for light in the blue wavelength region has spectral sensitivity substantially only in the blue wavelength region.

  The array of the second pixels 42 is provided on the surface of the semiconductor substrate 40 that faces the second scintillator 32. Each of the second pixels 42 receives a fluorescence emitted from the second scintillator 32 and generates a charge, and a readout circuit unit 46 for reading out the charge generated in the photoelectric conversion element 45. The photoelectric conversion element 45 and the readout circuit unit 46 are both formed on the semiconductor substrate 40. Since the photoelectric conversion element 45 is also formed on the semiconductor substrate 40, the photoelectric conversion element 45 has spectral sensitivity only in a substantially blue wavelength region.

  Note that single crystal Si is typically used for the semiconductor substrate on which the photoelectric conversion element and its readout circuit portion are formed. In this example, the semiconductor substrate 40 has a band gap of single crystal Si. A semiconductor material such as SiC having a band gap greater than 1.1 eV is used, and the X-ray resistance of the photoelectric conversion elements 43 and 45 and the readout circuit portions 44 and 46 formed on the semiconductor substrate 40 is a single crystal Si semiconductor substrate. It is superior to what is formed. As described above, since the sensor panel 30 is exposed to the high energy component of the incident X-ray that passes through the first scintillator 31, the photoelectric conversion elements 43 and 45 and the readout circuit units 44 and 46 are excellent in X-ray resistance. preferable. In addition, the readout circuit portions 44 and 45 such as CCD and CMOS formed on the semiconductor substrate 40 are excellent in terms of readout speed.

  Next, the first scintillator 31 and the second scintillator 32 will be described.

  The first scintillator 31 that is arranged on the X-ray incident side of the sensor panel 30 and overlaps the array of the first pixels 41 has a K absorption edge in a relatively low energy region, and mainly uses low energy components of incident X-rays. A fluorescent composition that absorbs and emits fluorescence, and has a fluorescence peak wavelength in a blue wavelength range that matches the spectral sensitivity of the first pixel 41 (the photoelectric conversion element 43 included in the pixel 41). Formed by the composition. As such a fluorescent composition, europium activated barium fluoride halide (BaFX: Eu (X is a halogen such as Br or I)) can be exemplified.

The second scintillator 32 disposed on the opposite side of the first scintillator 31 with the sensor panel 30 interposed therebetween and overlapping the array of the second pixels 42 is a fluorescent composition in which the K absorption end forms the first scintillator 31. A fluorescent composition that mainly absorbs high energy components of incident X-rays and emits fluorescence, and the peak wavelength of the fluorescence is the second pixel 42 (included in the pixel 42). Formed of a fluorescent composition in a blue wavelength range that matches the spectral sensitivity of the photoelectric conversion element 45). As such a fluorescent composition, calcium tungstate (CaWO ₄ ) can be exemplified.

  In the X-ray image detection apparatus 3 configured as described above, incident X-rays first enter the first scintillator 31, and the low energy component is mainly absorbed by the first scintillator 31. In the first scintillator 31, fluorescence Lb in a blue wavelength region corresponding to the absorbed X-rays is generated, and this fluorescence Lb is detected by the array of the first pixels 41. Thereby, image data based on the low energy component of the incident X-ray is generated.

  The high energy component of the incident X-ray is not absorbed by the first scintillator 31, passes through the first scintillator 31 and the sensor panel 30 and enters the second scintillator 32, and this second scintillator. 32 is absorbed. In the second scintillator 32, fluorescence Lb in a blue wavelength range corresponding to the absorbed X-rays is generated, and this fluorescence Lb is detected by the array of second pixels 42. Thereby, image data based on the high energy component of incident X-rays is generated.

  Here, the fluorescence Lb generated in the first scintillator 31 and the fluorescence Lb generated in the second scintillator 32 are both in the blue wavelength region, and the first pixel 41 to detect the fluorescence Lb of the first scintillator 31 is used. Is sensitive to the fluorescence Lb of the second scintillator 32 as well.

  A part of the fluorescence Lb generated in the second scintillator 32 is not received by the array of the second pixels 42 and is directed to the array of the first pixels 41 provided on the opposite surface of the semiconductor substrate 40. May go forward. However, as described above, the semiconductor substrate 40 has an absorption characteristic with respect to light in the blue wavelength region, and is not received by the array of the second pixels 42 and is directed toward the array of the first pixels 41. The fluorescence Lb of the second scintillator 32 that travels is absorbed by the semiconductor substrate 40. Therefore, in the array of the first pixels 41, the fluorescence Lb of the second scintillator 32 is prevented from being detected by being mixed with the fluorescence Lb of the first scintillator 31. Thereby, in the image data based on the low energy component of the incident X-ray, the influence of the high energy component of the incident X-ray is reduced.

  Further, the second pixel 42 that should detect the fluorescence Lb of the second scintillator 32 is sensitive to the fluorescence Lb of the first scintillator 31, but is not received by the array of the first pixels 41. The fluorescence Lb of the first scintillator 31 that proceeds toward the array of the second pixels 42 is absorbed by the semiconductor substrate 40. Therefore, in the array of the second pixels 42, the fluorescence Lb of the first scintillator 31 is prevented from being mixed with the fluorescence Lb of the second scintillator 32 and detected. Thereby, in the image data based on the high energy component of the incident X-ray, the influence of the low energy component of the incident X-ray is reduced.

  As described above, according to the X-ray image detection device 3, even if the fluorescence generated in the second scintillator 32 is included in the blue wavelength region, they are absorbed by the semiconductor substrate 40. Thus, fluorescence contamination is prevented and the image data acquired by the array of first pixels 41 depends only on the low energy region components of the incident X-rays. Thereby, a favorable energy subtraction image can be obtained.

  FIG. 4 shows a modification of the X-ray image detection apparatus 3.

  In the X-ray image detection apparatus 3A shown in FIG. 4, in the first scintillator 31, the reflective layer 33 that reflects the fluorescence Lb generated in the first scintillator 31 is provided on the surface opposite to the side facing the sensor panel 30. Is provided. Of the fluorescence Lb generated in the first scintillator 31, the fluorescence Lb that has traveled to the side opposite to the sensor panel 30 and reached the reflection layer 33 is reflected by the reflection layer 33 toward the sensor panel 30. Thereby, the detection sensitivity in the array of the first pixels 41 is improved.

  Similarly, in the second scintillator 32, a reflective layer 34 that reflects the fluorescence Lb generated in the second scintillator 32 is provided on the surface opposite to the side facing the sensor panel 30. The detection sensitivity in the 42 array is improved.

  As a material for forming the reflective layers 33 and 34, for example, aluminum or an aluminum alloy can be used.

  FIG. 5 shows another modification of the X-ray image detection apparatus 3.

  The X-ray image detection device 3B shown in FIG. 5 includes a sensor panel 30B, and a first scintillator 31 and a second scintillator 32 that are arranged so as to sandwich the sensor panel therebetween. The sensor panel 30B includes a semiconductor substrate 40, and an array of first pixels 41B and an array of second pixels 42B provided on the semiconductor substrate 40.

  The array of the first pixels 41B is provided on the surface of the semiconductor substrate 40 that faces the first scintillator 31. Each of the first pixels 41B receives a fluorescence emitted from the first scintillator 31, generates a charge, and a readout circuit unit 44 for reading out the charge generated in the photoelectric conversion element 43B. It consists of and. The photoelectric conversion element 43B is an organic photoelectric conversion film (hereinafter referred to as a blue absorption OPC (Organic photoelectric conversion) film) that selectively absorbs a blue wavelength region and generates charges as a photoelectric conversion film provided between a pair of electrodes. ), And is formed on the semiconductor substrate 40.

  The array of the second pixels 42 </ b> B is provided on the surface of the semiconductor substrate 40 that faces the second scintillator 32. Each of the second pixels 42B receives a fluorescence emitted from the second scintillator 32 and generates a charge, and a readout circuit unit 46 for reading out the charge generated in the photoelectric conversion element 45B. It consists of and. The photoelectric conversion element 45 </ b> B is an organic photoelectric conversion element using a blue absorption OPC film as a photoelectric conversion film provided between a pair of electrodes, and is formed on the semiconductor substrate 40.

  Since the OPC film generally has a sharp absorption spectrum in the visible region, the photoelectric conversion elements 43B and 45B have spectral sensitivity only in the substantially blue wavelength region. In addition, due to the sharp absorption spectrum in the visible region of the OPC film, the photoelectric conversion element using the OPC film hardly absorbs X-rays, and therefore has excellent X-ray resistance and absorbs X-rays. The generated noise is suppressed.

  As the blue absorbing OPC film, for example, an OPC film described in JP-A-2009-218599 can be used.

  FIG. 6 shows another example of a radiation image detection apparatus for explaining an embodiment of the present invention. In addition, description is abbreviate | omitted or simplified by attaching | subjecting a common code | symbol to the element which is common in the X-ray image detection apparatus 3 mentioned above.

  The X-ray image detection apparatus 103 shown in FIG. 6 includes a sensor panel 130, and a first scintillator 31 and a second scintillator 132 that are arranged so as to sandwich the sensor panel 130 therebetween. The radiation image detection apparatus 103 is arranged so that X-rays enter from the first scintillator 31 side.

  The sensor panel 130 includes a semiconductor substrate 40 that has absorption characteristics with respect to light in a blue wavelength range, and an array of first pixels 41 and an array of second pixels 142 provided on the semiconductor substrate 40. .

  The array of the first pixels 41 is provided on the surface of the 40th semiconductor substrate facing the first scintillator 31. Each of the first pixels 41 has spectral sensitivity substantially only in the blue wavelength region.

  The second pixels 142 are provided on the surface of the semiconductor substrate 40 facing the second scintillator 132, and each of the second pixels 142 receives fluorescence emitted from the second scintillator 132. The photoelectric conversion element 143 that generates charges and the readout circuit unit 146 for reading out the charges generated in the photoelectric conversion element 143 are configured.

  The first scintillator 31 is a fluorescent composition that has a K absorption edge in a relatively low energy range, mainly absorbs a low energy component of incident X-rays, and emits fluorescence, and has a peak wavelength of fluorescence. For example, it is formed of a fluorescent composition such as BaFX: Eu in the blue wavelength range that matches the spectral sensitivity of one pixel 41 (the photoelectric conversion element 43 included in the pixel 41).

The second scintillator 132 is a fluorescent composition whose K absorption edge is in a higher energy region than the fluorescent composition forming the first scintillator 31 and emits fluorescence mainly by absorbing high energy components of incident X-rays. And a fluorescent composition that emits fluorescence having a peak wavelength in a green wavelength range (495 nm to 570 nm) that deviates from the blue wavelength range. Examples of such a fluorescent composition include terbium-activated gadolinium oxide (Gd ₂ O ₂ S: Tb).

  As long as the second pixel 142 has spectral sensitivity in the green wavelength region where the main peak wavelength of the fluorescence generated in the second scintillator 132 is, the second pixel 142 is spectrally separated into another wavelength region (for example, the blue wavelength region). Although it may have sensitivity, in the X-ray image detection apparatus 103 of this example, the photoelectric conversion element 145 included in the second pixel 142 has a green wavelength as a photoelectric conversion film provided between the pair of electrodes. An organic photoelectric conversion element using an OPC film (hereinafter referred to as a green absorption OPC film) that selectively absorbs a region to generate a charge and has a spectral sensitivity only in a substantially green wavelength region. Yes.

  As the green absorption OPC film, for example, an OPC film using quinacridone described in JP-A-2009-32854 can be used.

  In the X-ray image detection apparatus 103 configured as described above, incident X-rays first enter the first scintillator 31, and mainly the low energy component is absorbed by the first scintillator 31. In the first scintillator 31, fluorescence Lb in a blue wavelength region corresponding to the absorbed X-rays is generated, and this fluorescence Lb is detected by the array of the first pixels 41. Thereby, image data based on the low energy component of the incident X-ray is generated.

  The high energy component of the incident X-rays is not absorbed by the first scintillator 31, passes through the first scintillator 31 and the sensor panel 130, and enters the second scintillator 132, and this second scintillator Absorbed by 132. In the second scintillator 132, fluorescence Lg in the green wavelength region corresponding to the absorbed X-rays is generated, and this fluorescence Lg is detected by the array of second pixels 142. Thereby, image data based on the high energy component of incident X-rays is generated.

Here, the peak wavelength of the fluorescence Lg generated in the second scintillator 132 is in the green wavelength range that is out of the blue wavelength range where the spectral sensitivity of the first pixel 41 is, and a part of the fluorescence Lg is the second wavelength. Even if the light reaches the array of the first pixels 41 without being received by the array of the pixels 142, it is not detected by the array of the first pixels 41. In addition, when Gd ₂ O ₂ S: Tb is used for the fluorescent composition forming the second scintillator 132, the fluorescence generated in the second scintillator 132 includes a little fluorescence Lb in the blue wavelength region. The fluorescence Lb is absorbed by the semiconductor substrate 40 having an absorption characteristic with respect to light in the blue wavelength region, and therefore is not detected by the array of the first pixels 41. Therefore, in the array of the first pixels 41, the fluorescence of the second scintillator 32 is prevented from being mixed with the fluorescence of the first scintillator 31 and detected.

  Note that the second pixel 142 has spectral sensitivity substantially only in the green wavelength region and does not have spectral sensitivity in the blue wavelength region. The fluorescence Lb in the blue wavelength region that occurs in the first scintillator 31 is larger than the fluorescence Lb in the blue wavelength region that occurs in the second scintillator 132, and tentatively, part of the fluorescence Lb that occurs in the first scintillator 31 Is detected by the array of second pixels 142 even if it reaches the array of second pixels 142 without being received by the array of first pixels 41 and not sufficiently absorbed by the semiconductor substrate 40. Never happen. Therefore, in the array of the second pixels 142, the fluorescence Lb of the first scintillator 31 is prevented from being detected by being mixed with the fluorescence Lg of the second scintillator 132.

  FIG. 7 shows a modification of the X-ray image detection apparatus 103.

  The X-ray image detection apparatus 103A shown in FIG. 7 includes a sensor panel 130A, and a first scintillator 31 and a second scintillator 132 that are arranged so as to sandwich the sensor panel 130A. The sensor panel 130 </ b> A includes a semiconductor substrate 40, and an array of first pixels 141 and an array of second pixels 142 provided on the semiconductor substrate 40.

  The array of the first pixels 141 is provided on the surface of the semiconductor substrate 40 on the side facing the first scintillator 31. The photoelectric conversion element 143 included in each of the first pixels 141 is an organic photoelectric conversion element in which a blue absorption OPC film is used as a photoelectric conversion film provided between a pair of electrodes, and has a substantially blue wavelength range. Only has a spectral sensitivity, and is formed on the semiconductor substrate 40. Note that the reading circuit portion 144 included in the first pixel 142 is formed on the semiconductor substrate 40.

  In the X-ray image detection apparatuses 103 and 103A described above, the first pixel 141 has been described as having a spectral sensitivity only in a substantially blue wavelength range. However, in these X-ray image detection apparatuses, These pixels may have spectral sensitivity even in a wavelength region outside of blue.

  In the X-ray image detection apparatuses 103 and 103A described above, the fluorescence Lb of the first scintillator 31 is included in the blue wavelength range absorbed by the semiconductor substrate 40, and the array of the second pixels 142 is the semiconductor substrate 40. Are provided on the side opposite to the side where the array of the first pixels 41 is provided. In such a configuration, a part of the fluorescence Lg in the green wavelength region of the second scintillator 132 is not received by the array of the second pixels 142 and passes through the semiconductor substrate 40 and reaches the array of the first pixels. In this case, if the first pixel also has spectral sensitivity in the green wavelength range, this fluorescence Lg is also detected by the first pixel array. That is, the image data generated by the first array of pixels is based on the low energy component and the high energy component of the incident X-ray.

  However, even if a part of the fluorescent light Lb in the blue wavelength region of the first scintillator 31 is not received by the first pixel array, they are absorbed by the semiconductor substrate 40, and thus the second pixel 142. Are not detected by the array. Thus, the image acquired by the array of second pixels 142 is based on the high energy component of incident X-rays. Thus, since the image data generated by the array of the second pixels 142 is based on one energy component (in this example, a high energy component) of incident X-rays, an energy subtraction image is generated. There is no hindrance.

  Also in the X-ray image detection devices 3, 3A, 3B described above, the fluorescence of the first scintillator 31 is included in the blue wavelength range absorbed by the semiconductor substrate 40, and the array of the second pixels 42, 42B. Is provided on the opposite side of the semiconductor substrate 40 from the side on which the array of the first pixels 41 and 41B is provided. Also in these X-ray image detection devices, the first pixel is provided on the semiconductor substrate 40. It is not limited to one having spectral sensitivity only in the blue wavelength region having absorption characteristics.

  FIG. 8 shows a modification of the X-ray image detection apparatus 103A.

  In the X-ray image detection apparatus 103B shown in FIG. 8, the array of the first pixels 141 and the array of the second pixels 142 provided on the sensor panel 130B are both on the side facing the first scintillator 31 in the semiconductor substrate 40. The organic photoelectric conversion element 143 included in the first pixel 141 and the organic photoelectric conversion element 145 included in the second pixel 142 are formed on the semiconductor substrate 40, and have a single layer. It is composed. Thereby, the thickness of the X-ray image detection apparatus can be reduced as compared with the case where an array of photoelectric conversion elements is provided on each of both surfaces of the semiconductor substrate 40.

  In the illustrated example, the first pixel 141 and the second pixel 142 are each arranged in a double column, and the column of the first pixel 141 and the column of the second pixel 142 are alternately arranged. However, the first pixels 141 and the second pixels 142 are arranged in a staggered manner, and the second pixels 142 are arranged between two adjacent first pixels 141 in each row and each column. Also good.

  In the X-ray image detection apparatus 103 </ b> B configured as described above, incident X-rays first enter the first scintillator 31, and the low energy component is mainly absorbed by the first scintillator 31. In the first scintillator 31, fluorescence Lb in a blue wavelength region corresponding to the absorbed X-rays is generated, and this fluorescence Lb is detected by the array of the first pixels 141. Thereby, image data based on the low energy component of the incident X-ray is generated.

  The high energy component of the incident X-ray is not absorbed by the first scintillator 31, passes through the first scintillator 31 and the sensor panel 130B, enters the second scintillator 132, and this second scintillator. Absorbed by 132. In the second scintillator 132, fluorescence Lg in the green wavelength region corresponding to the absorbed X-rays is generated, and this fluorescence Lg passes through the semiconductor substrate 40 and is detected by the array of the second pixels 142. Thereby, image data based on the high energy component of incident X-rays is generated.

  The above-described X-ray image detection apparatuses 3 and 103 and modifications thereof mainly utilize the difference in K absorption edge between the fluorescent composition forming the first scintillator and the fluorescent composition forming the second scintillator. Although the low energy component and the high energy component of incident X-rays are separated, the low X-ray intensity of incident X-rays is determined by utilizing the difference in transmittance due to the energy of X-rays regardless of the K absorption edge of the fluorescent composition. The energy component and the high energy component can also be separated and will be described below.

  FIG. 9 shows another example of the radiation image detection apparatus for explaining the embodiment of the present invention. Note that elements common to the above-described X-ray image detection apparatuses 3 and 103 and modifications thereof are denoted by the same reference numerals, and description thereof is omitted or simplified.

  The X-ray image detection apparatus 203 shown in FIG. 9 includes a sensor panel 230 and a first scintillator 231 and a second scintillator 232 that are arranged so as to sandwich the sensor panel 230 therebetween. The radiation image detection apparatus 203 is arranged so that X-rays enter from the first scintillator 231 side.

  The sensor panel 230 includes a semiconductor substrate 40 having absorption characteristics with respect to light in a blue wavelength region, and an array of first pixels 41 and an array of second pixels 142 provided on the semiconductor substrate 40. .

  The array of the first pixels 41 is provided on the surface of the 40th semiconductor substrate facing the first scintillator 31. The photoelectric conversion element and the readout circuit portion included in each of the first pixels 41 are both formed on the semiconductor substrate 40, and the first pixel 41 has a spectral sensitivity substantially only in the blue wavelength region. is doing.

  The array of the second pixels 142 is provided on the surface of the semiconductor substrate 40 on the side facing the second scintillator 132. The photoelectric conversion element included in each of the second pixels 142 is an organic photoelectric conversion element in which a green absorption OPC film is used as a photoelectric conversion film provided between a pair of electrodes, and has a substantially green wavelength range. Only has a spectral sensitivity, and is formed on the semiconductor substrate 40. Note that a reading circuit portion included in the second pixel 142 is formed on the semiconductor substrate 40.

The first scintillator 231 and the second scintillator 232 are both formed of a mixture of the first fluorescent composition and the second fluorescent composition. The first fluorescent composition is, for example, BaFX: Eu or the like, in which the peak wavelength of fluorescence is in a blue wavelength range that matches the spectral sensitivity of the first pixel 41. In addition, the second fluorescent composition is, for example, Gd ₂ O ₂ S: Tb or the like, in which the peak wavelength of fluorescence is in the green wavelength range that is out of the blue wavelength range.

  In the X-ray image detection apparatus 103B configured as described above, incident X-rays first enter the first scintillator 231. The low energy component of the incident X-ray is inferior to the high energy component, and most of it is absorbed by the first scintillator 231. The first scintillator 231 has, in accordance with the absorbed X-rays, fluorescence Lb in the blue wavelength range resulting from the first fluorescent composition and fluorescence Lg in the green wavelength range resulting from the second fluorescent composition. Arise. Among these fluorescences, the fluorescence Lb in the blue wavelength region caused by the first fluorescent composition is detected by the array of the first pixels 41. Thereby, image data based on the low energy component of the incident X-ray is generated.

  The high energy component of the incident X-ray is not absorbed by the first scintillator 231 because of its high transparency, and passes through the first scintillator 231 and the sensor panel 230 to enter the second scintillator 232. Incident light is absorbed by the second scintillator 232. The second scintillator 232 has, in accordance with the absorbed X-rays, the fluorescence Lb in the blue wavelength range caused by the first fluorescence composition and the fluorescence Lg in the green wavelength range caused by the second fluorescence composition. Arise. Among these fluorescences, the fluorescence Lb in the blue wavelength region in which the first pixel 41 has spectral sensitivity is absorbed by the semiconductor substrate 40 having absorption characteristics with respect to the light in the blue wavelength region. It is not detected by the array of pixels 41. Therefore, in the array of the first pixels 41, the fluorescence of the second scintillator 232 is prevented from being mixed with the fluorescence of the first scintillator 231 and detected.

  It should be noted that the fluorescence Lg in the green wavelength region caused by the second fluorescent composition generated in the first scintillator 231 reaches the array of the second pixels 142 through the semiconductor substrate 40, and this fluorescence Lg Is also detected by an array of second pixels 142. That is, the image data generated by the array of the second pixels 142 is based on the high energy component and low energy component of the incident X-ray. However, since the image data generated by the array of the first pixels 41 is based on one energy component (low energy component in this example) of the incident X-ray, there is no problem in generating the energy subtraction image. Absent.

  In this way, by utilizing the difference in transmittance due to the X-ray energy, the low energy component and the high energy component of the incident X-ray are separated, whereby the same fluorescence is applied to the first scintillator 231 and the second scintillator 232. By using the composition, the apparatus configuration can be simplified, and the thickness of the scintillator (the first scintillator 231 in this example) disposed on the X-ray incident side can be reduced.

  FIG. 10 shows a modification of the X-ray image detection apparatus 203.

  An X-ray image detection apparatus 203A shown in FIG. 10 includes a sensor panel 230A, and a first scintillator 231 and a second scintillator 232 arranged so as to sandwich the sensor panel 230A. The sensor panel 230 </ b> A includes a semiconductor substrate 40, and an array of first pixels 141 and an array of second pixels 142 provided on the semiconductor substrate 40.

  The array of the first pixels 141 is provided on the surface of the semiconductor substrate 40 on the side facing the first scintillator 231. The photoelectric conversion element included in each of the first pixels 141 is an organic photoelectric conversion element in which a blue absorption OPC film is used as a photoelectric conversion film provided between a pair of electrodes, and has a substantially blue wavelength range. Only has a spectral sensitivity and is formed on the semiconductor substrate 40.

  FIG. 11 shows a modification of the X-ray image detection apparatus 203A.

  In the X-ray image detection apparatus 203B shown in FIG. 11, the array of the first pixels 141 and the array of the second pixels 142 provided on the sensor panel 230B are both on the side facing the first scintillator 231 on the semiconductor substrate 40. The organic photoelectric conversion element included in the first pixel 141 and the organic photoelectric conversion element included in the second pixel 142 are formed on the semiconductor substrate 40 and constitute a single layer. ing.

  The X-ray image detection apparatus 203B is arranged so that X-rays enter from the second scintillator 232 side.

  In the X-ray image detection device 203B configured as described above, incident X-rays first enter the second scintillator 232. Most of the low energy component of the incident X-ray is absorbed by the second scintillator 232. The second scintillator 232 has, in accordance with the absorbed X-rays, the fluorescence Lb in the blue wavelength range caused by the first fluorescence composition and the fluorescence Lg in the green wavelength range caused by the second fluorescence composition. Arise. Among these fluorescences, the fluorescence Lb in the blue wavelength region resulting from the first fluorescent composition is absorbed by the semiconductor substrate 40. On the other hand, the fluorescent light Lg in the green wavelength region caused by the second fluorescent composition reaches the array of the first pixels 141 and the array of the second pixels 142 without being absorbed by the semiconductor substrate 40.

  High energy components of incident X-rays pass through the second scintillator 232 and the sensor panel 230, enter the first scintillator 231, and are absorbed by the first scintillator 232. Also in the first scintillator 231, the fluorescence Lb in the blue wavelength range caused by the first fluorescence composition and the fluorescence Lg in the green wavelength range caused by the second fluorescence composition depend on the absorbed X-rays. Arise. Among these fluorescences, the fluorescence Lb is detected by the first pixel 141 having spectral sensitivity only in the blue wavelength region. Thereby, image data based on the high energy component of incident X-rays is generated.

  It should be noted that the fluorescence Lg in the green wavelength region caused by the second fluorescent composition generated in the first scintillator 231 reaches the array of the second pixels 142 through the semiconductor substrate 40, and this fluorescence Lg Is also detected by an array of second pixels 142. That is, the image data generated by the array of the second pixels 142 is based on the high energy component and low energy component of the incident X-ray. However, since the image data generated by the array of the first pixels 141 is based on one energy component (high energy component in this example) of the incident X-ray, there is no problem in generating the energy subtraction image. Absent.

  The above-described radiographic image detection apparatus can detect a radiographic image with high sensitivity and high definition, and is therefore required to detect a sharp image with a low radiation dose, such as an X-ray imaging apparatus for medical diagnosis such as mammography. It can be used by incorporating it into various devices. For example, it can be used for nondestructive inspection as an industrial X-ray imaging apparatus, or can be used as a detection apparatus for particle beams (α rays, β rays, γ rays) other than electromagnetic waves, and its application range is wide. .

DESCRIPTION OF SYMBOLS 1 X-ray imaging apparatus 2 X-ray source 3 X-ray image detection apparatus 4 Console 5 X-ray source holding | maintenance apparatus 6 Stand 10 X-ray source control part 11 High voltage generator 12 X-ray tube 13 Collimator 14 Collimator unit 15 Ceiling rail 16 Car Unit 17 Supporting unit 18 Main body 19 Holding unit 20 Control device 21 Input device 22 Image processing unit 23 Image storage unit 24 Monitor 25 I / F
26 Bus 30 Sensor panel 31 First scintillator (phosphor)
32 Second scintillator (phosphor)
40 Semiconductor substrate 41 First pixel 42 Second pixel

Claims (22)

A sensor panel having a substrate having absorption characteristics with respect to light in the first wavelength band, and an array of first pixels and an array of second pixels provided on the substrate;
A first phosphor that emits fluorescence including the first wavelength range when exposed to radiation in a first energy range;
A second phosphor that is disposed opposite to the first phosphor across the sensor panel and emits fluorescence when exposed to radiation in a second energy region;
With
The first pixel has spectral sensitivity substantially only in the first wavelength range, and the array is provided on the first phosphor side of the substrate, and the fluorescence generated in the first phosphor. Detect
The second pixel array is a radiation image detection device that detects fluorescence generated in the second phosphor. The radiological image detection apparatus according to claim 1,
The first phosphor comprises a first phosphor composition that emits fluorescence whose peak wavelength belongs to the first wavelength range,
The second phosphor is a radiological image detection apparatus comprising a second fluorescent composition having a K absorption edge for radiation different from that of the first fluorescent composition. The radiological image detection apparatus according to claim 2,
The K absorption edge of the first fluorescent composition is lower than the K absorption edge of the second fluorescent composition,
The first phosphor is a radiation image detection device disposed on a radiation incident side. The radiological image detection apparatus according to claim 3,
The peak wavelength of fluorescence emitted from the second fluorescent composition belongs to the first wavelength range,
The second pixel is a radiological image detection apparatus having spectral sensitivity in the first wavelength range. The radiological image detection apparatus according to claim 3,
The peak wavelength of the fluorescence emitted by the second fluorescent composition belongs to a second wavelength range that is out of the first wavelength range,
The second pixel is a radiological image detection apparatus having spectral sensitivity in the second wavelength range. The radiological image detection apparatus according to claim 5,
The radiographic image detection apparatus, wherein the second pixel array is provided on the same side of the substrate as the first pixel array. The radiological image detection apparatus according to claim 1,
Each of the first phosphor and the second phosphor has a first fluorescent composition whose peak wavelength belongs to the first wavelength range, and a second peak whose peak wavelength belongs to the second wavelength range. A fluorescent composition,
The second pixel is a radiological image detection apparatus having spectral sensitivity in the second wavelength range. The radiological image detection apparatus according to claim 7,
One of the first phosphor and the second phosphor is a radiation image detection device in which the thickness of one phosphor disposed on the radiation incident side is smaller than the thickness of the other phosphor. The radiological image detection apparatus according to claim 7 or 8,
The radiographic image detection apparatus, wherein the second pixel array is provided on the same side of the substrate as the first pixel array. A sensor panel having a substrate having absorption characteristics with respect to light in the first wavelength band, and an array of first pixels and an array of second pixels provided on the substrate;
A first phosphor that emits fluorescence contained in the first wavelength range by being exposed to radiation in a first energy range;
A second phosphor that is disposed opposite to the first phosphor across the sensor panel and emits fluorescence when exposed to radiation in a second energy region;
With
The first pixel array is provided on the first phosphor side of the substrate, detects fluorescence generated in the first phosphor,
The second pixel array is provided on the second phosphor side of the substrate, and detects a fluorescence generated in the second phosphor. It is a radiographic image detection apparatus of Claim 10, Comprising:
The first phosphor comprises a first phosphor composition that emits fluorescence whose peak wavelength belongs to the first wavelength range,
The second phosphor is a radiological image detection apparatus comprising a second fluorescent composition having a K absorption edge for radiation different from that of the first fluorescent composition. The radiological image detection apparatus according to claim 11,
The K absorption edge of the first fluorescent composition is lower than the K absorption edge of the second fluorescent composition,
The first phosphor is a radiation image detection device disposed on a radiation incident side. The radiological image detection apparatus according to claim 12,
The peak wavelength of fluorescence emitted from the second fluorescent composition belongs to the first wavelength range,
The second pixel is a radiological image detection apparatus having spectral sensitivity in the first wavelength range. The radiological image detection apparatus according to claim 12,
The peak wavelength of the fluorescence emitted by the second fluorescent composition belongs to a second wavelength range that is out of the first wavelength range,
The second pixel is a radiological image detection apparatus having spectral sensitivity in the second wavelength range. The radiological image detection apparatus according to any one of claims 1 to 14,
The substrate is made of a semiconductor material having a band gap of 2.8 eV or more,
The first wavelength range is a radiological image detection apparatus having a wavelength of 440 nm or less. The radiological image detection apparatus according to claim 15,
The radiographic image detection apparatus, wherein the semiconductor material is any one selected from the group consisting of SiC, ZnO, and GaN. The radiological image detection apparatus according to claim 15 or 16,
The first pixel includes a photoelectric conversion element and a readout circuit unit that reads out charges generated in the photoelectric conversion element, and the photoelectric conversion element and the readout circuit unit are both formed on the substrate. Detection device. The radiological image detection apparatus according to claim 15 or 16,
The first pixel includes a photoelectric conversion element and a readout circuit unit that reads out electric charges generated in the photoelectric conversion element. The readout circuit unit is formed on the substrate, and the photoelectric conversion element is an organic photoelectric conversion element. A radiological image detection apparatus which is a conversion element and is formed on the substrate. The radiological image detection apparatus according to claim 4 or 13,
The first fluorescent composition is BaFX: Eu (X is halogen),
Said second fluorescent composition, the radiation image detection apparatus is CaWO _4. The radiographic image detection apparatus according to any one of claims 5, 7, and 14,
The first fluorescent composition is BaFX: Eu (X is halogen),
The second fluorescent composition is a radiological image detection apparatus in which Gd ₂ O ₂ S: Tb is used. The radiological image detection apparatus according to any one of claims 1 to 20,
In each of the first phosphor and the second phosphor, a radiation image detection device in which a reflection layer that reflects fluorescence generated in the phosphor is provided on the side opposite to the side facing the sensor panel . The radiological image detection apparatus according to any one of claims 1 to 21,
An image processing unit for generating an energy subtraction image using the first image data acquired by the first pixel array and the second image data acquired by the second pixel array;
A radiographic apparatus comprising:

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