JP2013088373A - X-ray sensor and x-ray diagnostic apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase a frame rate of an x-ray sensor.SOLUTION: An x-ray sensor is configured so that one face side is an x-ray incident face and the other face side is an electron beam incident face. A photoelectric conversion film 12 with a thin film-like electrode 18 and an electron source 16 for applying an electron beam 26 to the photoelectric conversion film 12 are arranged on the x-ray incident face side. The electron source 16 has a plurality of electron beams 26 to be selected and applied in each scanning line. The photoelectric conversion film 12 includes conductive band-like electron incident electrodes 22 formed on positions respectively corresponding to scanning lines of electron beams on the electron beam incidence face. The thin film-like electrode 18 on the x-ray incident face side has a constitution divided into a plurality of bands almost orthogonal to the electron incident electrodes 22.

Description

  The present invention relates to, for example, an X-ray sensor and an X-ray diagnostic apparatus using the X-ray sensor.

  A conventional X-ray sensor has a configuration in which one surface side is an X-ray incident surface, the other surface side is an electron beam incident surface, a photoelectric conversion film having a thin film electrode on the X-ray incident surface side, and an electron beam of the photoelectric conversion film And an electron source that is provided opposite to the incident surface side and irradiates the photoelectric conversion film with an electron beam.

  When X-rays enter from the X-ray incident surface side of the photoelectric conversion film, electrons and holes corresponding to the incident X-ray dose are generated in the film near the thin film electrode. Of these, holes are accelerated by the electric field applied to the photoelectric conversion film via the thin film electrode, and are avalanche-multiplied by repeating collision ionization to generate new electron / hole pairs. As a result, a secondary pattern of holes generated and multiplied in accordance with the intensity of incident X-rays is formed on the electron source side of the light conversion film layer.

  An electron beam is emitted from the electron source to the holes in the light conversion film layer, and the light conversion film layer is scanned pixel by pixel. At this time, video information corresponding to the intensity of the X-ray can be obtained by taking out the current that flows when the holes and electrons of the electron beam are combined through the thin film electrode (for example, Patent Document 1 below). ).

US Pat. No. 5,882,222

  The problem with the conventional X-ray sensor is that the frame rate for generating one X-ray image is slow.

  As described above, in the configuration of the conventional X-ray sensor, when extracting video information according to the intensity of the X-ray, the electron source scans the light conversion film layer for each pixel, and at that time Video information corresponding to the intensity of X-rays was obtained by taking out the flowing current through the thin film electrode.

  In this case, when one piece of video information is extracted, the number of scans equal to the number of pixels of one video is required, and as a result, the frame rate is slowed down.

  Accordingly, the present invention aims to increase the frame rate of the X-ray sensor.

  In order to achieve this object, the X-ray sensor of the present invention comprises a photoelectric conversion film having an X-ray incident surface on one side, an electron beam incident surface on the other side, and a thin film electrode on the X-ray incident surface side, An electron source that irradiates the photoelectric conversion film with an electron beam, and the electron source includes a plurality of electron beams that are selectively irradiated for each scanning line, and the photoelectric conversion film includes electrons on an electron beam incident surface. A conductive band-shaped electron incident electrode is provided at a position corresponding to the scanning line of the beam, and the thin-film electrode on the X-ray incident surface side is divided into a plurality of bands substantially orthogonal to the electron incident electrode. Yes, and this achieves the intended purpose.

  As described above, the X-ray sensor of the present invention has an X-ray incident surface on one surface side, an electron beam incident surface on the other surface side, a photoelectric conversion film having a thin film electrode on the X-ray incident surface side, and an electron beam. An electron source for irradiating the photoelectric conversion film, the electron source having a plurality of electron beams selected and irradiated for each scanning line, and the photoelectric conversion film scanning the electron beam on the electron beam incident surface. A conductive band-shaped electron incident electrode is provided at a position corresponding to the line, and the thin film-shaped electrode on the X-ray incident surface side is divided into a plurality of bands substantially orthogonal to the electron incident electrode. The frame rate of the X-ray sensor can be increased.

  That is, the photoelectric conversion film is provided with a conductive band-shaped electron incident electrode at a position corresponding to the scanning line of the electron beam on the electron beam incident surface, and the electron source selects the electron beam with respect to the electron incident electrode. Thus, it becomes possible to perform scanning for each line.

  Next, since the thin film electrode on the X-ray incident surface side of the photoelectric conversion film is divided into a plurality of strips substantially orthogonal to the electron incident electrode, the current values of the plurality of thin film electrodes are simultaneously read for each scanning line. Thus, the X-ray sensitivity corresponding to a plurality of pixels corresponding to the position where the scanning line and the thin film electrode are orthogonal to each other can be read simultaneously. As a result, both the number of scanning times and the number of current value readings can be reduced. The frame rate of the sensor can be increased.

The block diagram of the X-ray diagnostic apparatus concerning embodiment of this invention The block diagram of the X-ray diagnostic apparatus concerning embodiment of this invention The perspective view which shows the external appearance of the X-ray sensor concerning embodiment of this invention Sectional drawing of the X-ray sensor concerning embodiment of this invention Sectional drawing of the principal part of the X-ray sensor concerning embodiment of this invention Control block diagram of X-ray sensor according to an embodiment of the present invention Sectional drawing of the principal part of the X-ray sensor concerning embodiment of this invention Sectional drawing of the principal part of the X-ray sensor concerning embodiment of this invention The perspective view which shows the external appearance of the X-ray sensor concerning embodiment of this invention

(Embodiment 1)
Hereinafter, an embodiment of an X-ray sensor according to the present invention and an X-ray diagnostic apparatus using the X-ray sensor will be described with reference to the accompanying drawings. Note that the attached drawings are schematic views for easy understanding.

  First, the overall configuration of the X-ray diagnostic apparatus according to this embodiment will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a configuration diagram of an X-ray diagnostic apparatus according to an embodiment of the present invention. As shown in FIG. 1, the X-ray diagnostic apparatus includes an X-ray source 1 and an X-ray sensor 2 disposed to face the X-ray source 1 at a predetermined interval. By irradiating the imaging target person 3 with a line and causing the X-ray transmitted through the imaging target person 3 to enter the X-ray sensor 2, the internal state of the imaging target person 3 is visualized.

  Specifically, the X-ray source 1 is provided at one end of an arm 4 having a substantially semicircular shape when viewed from the side, and the X-ray sensor 2 is provided at the other end of the arm 4. In this way, the X-ray source 1 and the X-ray sensor 2 are arranged to face each other at a predetermined interval. Therefore, since the X-ray source 1 and the X-ray sensor 2 can be arranged to face each other with the arm 4 sandwiching the imaging target person 3 lying on the bed 5, the X-ray source 1 is irradiated and transmitted through the imaging target person 3. X-rays can be detected by the X-ray sensor 2.

  The arm 4 is rotatably attached to the apparatus main body 6. The apparatus body 6 incorporates a drive device (not shown) that rotates the arm 4. By doing in this way, it becomes possible to visualize the internal state of the person to be imaged 3 from various angles.

  FIG. 2 is a block diagram of the X-ray diagnostic apparatus according to the embodiment of the present invention.

  As shown in FIG. 2, the X-ray source 1 is connected to an X-ray control unit 7, and the X-ray control unit 7 is connected to a controller 8. The controller 8 controls the overall operation of the X-ray diagnostic apparatus. The X-ray control unit 7 controls an X-ray irradiation operation and an X-ray irradiation amount by the X-ray source 1 according to a command signal from the controller 8.

  The X-ray sensor 2 is connected to the image processing unit 9. The image processing unit 9 detects an electric signal (photoelectric conversion signal) extracted from the X-ray sensor 2 and performs image processing. The signal processed by the image processing unit 9 is transmitted to the controller 8. The controller 8 displays an image based on the amount (intensity) of X-rays detected by the X-ray sensor 2, that is, an image displaying an internal state of the imaging subject 3 on the monitor 10.

  The X-ray sensor 2 is also connected to the electron source control unit 11. The electron source control unit 11 is also connected to the controller 8. The electron source control unit 11 controls an electron beam irradiation operation and an electron beam irradiation amount by an electron source, which will be described later, in accordance with a command signal from the controller 8.

  A drive device (not shown) for rotating the arm 4 built in the apparatus main body 6 is connected to the movement control unit 13, and the movement control unit 13 is connected to the controller 8. The movement control unit 13 controls the rotation operation of the arm 4 according to a command signal from the controller 8.

  An input unit 14 is further connected to the controller 8. The controller 8 comprehensively controls the operation of the entire X-ray diagnostic apparatus according to a command input from the input unit 14.

  Next, the X-ray sensor 2 according to this embodiment will be described with reference to FIGS. FIG. 3 is a perspective view showing an external appearance of the X-ray sensor 2 according to the embodiment of the present invention, FIG. 4 is a cross-sectional view of the X-ray sensor 2 according to the embodiment of the present invention, and FIG. It is sectional drawing of the target part 12 which is a photoelectric converting film of the X-ray sensor 2 concerning this embodiment, FIG. 6 is a control block diagram of the X-ray sensor 2 concerning embodiment of this invention.

  Hereinafter, the photoelectric conversion film of the X-ray sensor 2 will be described as a target portion.

  As shown in FIGS. 3 and 4, the X-ray sensor 2 includes a mounting substrate 15 having a rectangular shape when viewed in plan. Also, as shown in FIG. 4, a rectangular electron source 16 is provided on the main surface of the mounting substrate 15, and a target portion 12 is disposed above the electron source 16.

  FIG. 5 shows a configuration diagram of the target unit 12. The target portion 12 includes an X-ray transmissive substrate 17 that becomes an X-ray incident surface, a thin film electrode 18 and a hole injection blocking layer 19 that are sequentially provided on the back side of the X-ray incident surface of the X-ray transmissive substrate 17. And a photoconductive photoconversion film layer 20 having a charge multiplying function, an electron injection blocking layer 21, and an electron incident electrode 22.

  The light conversion film layer 20 of the target unit 12 is composed mainly of a-Se (amorphous selenium). Also, the injection of holes from the outside is blocked by the bonding of the thin film electrode 18, the hole injection blocking layer 19 formed of CeO 2 (cerium oxide), and the light conversion film layer 20, and Sb 2 S 3 (three The electron injection blocking layer 21 made of antimony sulfide) or Si3N4 (silicon nitride) and the light conversion film layer 20 are joined to prevent electron injection from the outside.

  As shown in FIG. 4, the X-ray transparent substrate 17 is disposed to face the mounting substrate 15 so that the electron injection blocking layer 21 of FIG. 5 faces the electron source 16. Thereby, the electron source 16 can irradiate an electron beam toward the surface on the electron injection blocking layer 21 side.

  The target unit 12 and the electron source 16 are configured to be vacuum-sealed in the main body case 2a as shown in FIG. 3 in order to enable photoelectric conversion of the X-ray irradiation energy.

  Next, the operation of the X-ray sensor 2 will be described with reference to FIG.

  First, the thin film electrode 18 of the target unit 12 is connected to a power source 24 of about 10 kV.

  The electron source 16 is connected to a power source 25 of about 10 to 80V.

  In this state, when X-rays 23 are incident from the X-ray incident surface side of the target unit 12 (upper side in FIG. 6), the light conversion film layer 20 on the electron source 16 side (lower side in FIG. 6) of the target unit 12 A secondary pattern of holes generated and multiplied according to the intensity of incident X-rays is formed.

  Next, in order to read the secondary pattern of holes as a current value, scanning is performed line by line from the electron beam 26 of the electron source 16 toward the electron incident electrode 22 provided on the lower surface of the target unit 12. Electrons will be emitted.

  Here, the configuration of the electron incident electrode 22 and the thin film electrode 18 will be described with reference to FIG.

  First, the electron incident electrode 22 is formed of a conductive metal such as aluminum, and 22a is positioned at a position corresponding to the scanning line of the electron beam on the electron beam incident surface (from the front of FIG. 6 to the depth direction). , 22b and 22e are provided in a strip shape arranged at a predetermined interval. Further, the thin film electrode 18 on the X-ray incident surface side is divided into a plurality of strips (arranged at predetermined intervals) substantially orthogonal to the electron incident electrode 22 as in 18a, 18b, and 18c. .

  In such a configuration, the electron beam 26 of the electron source 16 scans for each line toward the electron incident electrode 22 and emits electrons.

  In FIG. 6, electrons are first emitted from the electron beam 26e, and the electrons enter the electron incident electrode 22e. The holes generated in the film near the electron incident electrode 22e and the electrons incident from the electron incident electrode 22e. The current that flows when the electrons are combined is read from the thin film electrode 18. More specifically, the current value read from the thin film electrode 18a is a current value corresponding to the intensity of the incident X-ray of the pixel 27a where the electron incident electrode 22e and the thin film electrode 18a are orthogonal, and is read from the thin film electrode 18b. The current value corresponds to the intensity of the incident X-ray of the pixel 27b where the electron incident electrode 22e and the thin film electrode 18b are orthogonal to each other, and the current value read from the thin film electrode 18c is the same as that of the electron incident electrode 22e and the thin film shape. The current value corresponds to the intensity of the incident X-ray of the pixel 27c at which the electrode 18c is orthogonal.

  Each thin film electrode 18a, 18b, 18c has a configuration in which a current reading unit 28 is provided, and the control unit 29 converts a plurality of electron beams 26 of the electron source 16 into an electron beam 26a and an electron beam 26b. In turn, control is performed to select and irradiate each scanning line, and the intensity of incident X-rays of the pixel is determined by reading from the current reading unit 28 provided on the thin film electrode 18 corresponding to the selected scanning line. It becomes possible to read.

  For further detailed description, description will be made with reference to FIGS.

  7 and 8 are schematic views of the cross-sectional structure of the target unit 12 and the electron source 16.

  7 is a schematic diagram of a cross-sectional structure when FIG. 6 is viewed from the front, and FIG. 8 is a schematic diagram of the cross-sectional structure when FIG. 6 is viewed from the left side.

  As shown in FIG. 7, the target unit 12 includes an X-ray transmissive substrate 17 that becomes an X-ray incident surface, and a thin film electrode 18 that is sequentially provided on the back side of the X-ray incident surface of the X-ray transmissive substrate 17. A hole injection blocking layer 19 made of CeO2 (cerium oxide), a photoconductive photoconversion film layer 20 formed of a-Se (amorphous selenium) and having a charge multiplication function, and Sb2S3 (trisulfide trisulfide). The electron injection blocking layer 21 is made of antimony) or Si3N4 (silicon nitride), and the electron incidence electrode 22 is made of aluminum.

  The electron incident electrode 22 is formed of a conductive metal such as aluminum, and 22a and 22b are positioned at positions corresponding to the scanning lines of the electron beam on the electron beam incident surface (from the front of FIG. 7 to the depth direction). ,... 22f are provided in a strip shape separated by a predetermined distance. The length A of each electrode interval is about 100 μm. An electron beam 26 of the electron source 16 is provided at a position facing the electron incident electrode 22, and the interval between the electron beams is approximately 100 μm, similar to the electrode interval A of the electron incident electrode 22. Yes.

  Further, the distance B between the electron source 16 and the target unit 12 is about 400 μm.

  Further, as shown in FIG. 8, the thin film electrode 18 on the X-ray incident surface side is divided into a plurality of strips substantially orthogonal to the electron incident electrode 22 such as 18a, 18b and 18c. The distance C between the thin film electrodes is about 100 μm.

  The thin film electrode is divided by an ion doping method.

  In such a configuration, the operation of the target unit 12 and the electron source 16 will be described.

  When X-rays enter from the side of the X-ray transparent substrate 17 that becomes the X-ray incident surface of the X-rays 23 of the target unit 12, the incident X-ray dose is reduced in the film of the light conversion film layer 20 near the thin film electrode 18. Corresponding electrons and holes are generated. Of these holes, the holes are accelerated by the electric field applied to the light conversion film layer 20 through the thin film electrode 18 and are avalanche-multiplied by repeating collision ionization to generate new electron / hole pairs.

  As a result, a secondary pattern of holes generated and multiplied in accordance with the intensity of incident X-rays is formed on the side of the electron source 16 of the light conversion film layer 20.

  An electron beam is emitted from the electron source 16 to the holes of the light conversion film layer 20, and the light conversion film layer 20 is scanned line by line.

  In FIG. 7, first, the electron beam 26a is selected for the line corresponding to the electron incident electrode 22a, and electrons are emitted to the electron incident electrode 22a.

  In FIG. 8, the electrons radiated from the electron beam 26a spread to the electron incident electrode 22a, and the electrons are combined with the secondary pattern of holes formed on the lower surface of the light conversion film layer 20, and are positioned above the electrons. Current corresponding to the intensity of the X-rays flows through the thin film electrodes 18a to 18f. By extracting this current from each of the thin film electrodes 18a to 18f, the incident X-ray intensity of the pixel with respect to the line corresponding to the electron incident electrode 22a can be measured.

  By repeating this scanning from the electron beam 26a to the electron beam 26f, the incident X-ray intensity of the pixels positioned in a matrix by the electron incident electrode 22 and the thin film electrode 18 can be measured. Then, it becomes an X-ray image.

  As described above, the target unit 12 is provided with the conductive band-shaped electron incident electrode 22 at a position corresponding to the scanning line of the electron beam on the electron beam incident surface. By selecting and irradiating the electron beam 26, it becomes possible to perform scanning for each line. Next, the thin-film electrode 18 on the X-ray incident surface side of the target unit 12 is substantially orthogonal to the electron incident electrode 22. Since the current values of the plurality of thin film electrodes 18 are simultaneously read for each scanning line, the X corresponding to the plurality of pixels corresponding to the positions where the scanning lines and the thin film electrodes 18 are orthogonal to each other are divided. The line sensitivity can be read at the same time. As a result, the number of scans and the number of current values can be reduced, so that the frame rate of the X-ray sensor can be increased. A.

  Also, a conductive band-shaped electron incident electrode 22 is provided at a position corresponding to the scanning line of the electron beam, an electron beam is provided for the line with respect to the electron incident electrode 22, and the positive beam generated in the line by the electron beam is generated. Since electrons can be emitted to the holes, the electron source 16 can be configured with a smaller number of electron beams than when an electron beam is provided for each pixel.

  In this case, since the number of electron beams can be reduced, the sensitivity variation of the electron beams can also be reduced.

  The electron source 16 shown in FIGS. 6 to 8 has a line configuration in which electron beams are primarily arranged. However, as shown in FIG. A configuration in which an electron beam is arranged is also possible. With such a configuration, it is possible to reduce the amount of electron emission of one electron beam, so that the design tolerance of the electron source 16 can be increased.

  In addition, the light conversion film layer 20 in the present embodiment is configured by a sensitivity layer, but may be further configured by a relaxation layer, a hole trap layer, and a sensitivity layer in order from the X-ray incident surface.

  The hole trapping layer is a layer that traps holes generated by irradiation with X-rays or visible light. The relaxation layer and the hole trapping layer are provided with a scratch or a hole injection blocking layer. This is for the purpose of suppressing the occurrence of white flaws even when film thickness unevenness occurs.

  The charge multiplying function of the light conversion film layer 20 is based on the sensitivity layer, and the light conversion film layer 20 may be constituted only by the sensitivity layer.

Here, for the thin film electrode 18, a semiconductor substrate such as indium tin oxide (ITO), tin oxide, or Si is used. The hole injection blocking layer 19 is made of cerium oxide (CeO ₂ ), the relaxation layer is made of amorphous selenium (a-Se), and the hole trapping layer is made of amorphous selenium (a-Se). Lithium fluoride (LiF) is used, amorphous selenium (a-Se) is used for the sensitivity layer, and antimony sulfide (Sb ₂ S ₃ ) or Si ₃ N 4 (silicon nitride) is used for the electron injection blocking layer 21.

  As described above, the X-ray sensor of the present invention has an X-ray incident surface on one surface side, an electron beam incident surface on the other surface side, a photoelectric conversion film having a thin film electrode on the X-ray incident surface side, and an electron beam. An electron source for irradiating the photoelectric conversion film, the electron source having a plurality of electron beams selected and irradiated for each scanning line, and the photoelectric conversion film scanning the electron beam on the electron beam incident surface. A conductive band-shaped electron incident electrode is provided at a position corresponding to the line, and the thin film-shaped electrode on the X-ray incident surface side is divided into a plurality of bands substantially orthogonal to the electron incident electrode. The frame rate of the X-ray sensor can be increased.

  That is, the photoelectric conversion film is provided with a conductive band-shaped electron incident electrode at a position corresponding to the scanning line of the electron beam on the electron beam incident surface, and the electron source selects the electron beam with respect to the electron incident electrode. Thus, it becomes possible to perform scanning for each line.

  Next, since the thin film electrode on the X-ray incident surface side of the photoelectric conversion film is divided into a plurality of strips substantially orthogonal to the electron incident electrode, the current values of the plurality of thin film electrodes are simultaneously read for each scanning line. As a result, the X-ray sensitivity corresponding to a plurality of pixels corresponding to the position where the scanning line and the thin film electrode are orthogonal to each other can be read at the same time. The frame rate of the sensor can be increased.

  Therefore, application to an X-ray sensor or an X-ray diagnostic apparatus is highly expected.

DESCRIPTION OF SYMBOLS 1 X-ray source 2 X-ray sensor 3 Person to image 4 Arm 5 Bed 6 Apparatus main body 7 X-ray control part 8 Controller 9 Image processing part 10 Monitor 11 Electron source control part 12 Target part (photoelectric conversion film)
DESCRIPTION OF SYMBOLS 13 Movement control part 14 Input part 15 Mounting board 16 Electron source 17 X-ray transparent board | substrate 18 Thin film-like electrode 18a, 18b, 18c, 18d, 18e, 18f Thin film-like electrode 19 Hole injection | pouring prevention layer 20 Photoconversion film | membrane layer 21 Electron Injection blocking layer 22 Electron incident electrode 22a, 22b, 22c, 22d, 22e, 22f Electron incident electrode 23 X-ray 24 Power source 25 Power source 26 Electron beam 26a, 26b, 26c, 26d, 26e, 26f Electron beam 27a, 27b, 27c Pixel

Claims (5)

An X-ray incident surface on one surface side, an electron beam incident surface on the other surface side, a photoelectric conversion film having a thin film electrode on the X-ray incident surface side, and an electron source for irradiating the photoelectric conversion film with an electron beam, The electron source has a plurality of electron beams to be selectively irradiated for each scanning line, and the photoelectric conversion film has a conductive band-shaped electron incident at a position corresponding to the scanning line of the electron beam on the electron beam incident surface. An X-ray sensor in which an electrode is provided and a thin film electrode on the X-ray incident surface side is divided into a plurality of strips substantially orthogonal to the electron incident electrode. The X-ray sensor according to claim 1, wherein each photoelectric conversion film divided into a plurality of strips is provided with a current reading unit. The photoelectric conversion film is controlled to select and irradiate a plurality of electron beams of an electron source for each scanning line, and from a current reading unit provided on the thin film electrode corresponding to the selected scanning line. The X-ray sensor according to claim 2, further comprising a reading control unit. The photoelectric conversion film includes an X-ray transparent substrate from the X-ray incident surface side, a thin film electrode, a hole injection blocking layer, a light conversion layer sequentially provided on the back side of the X-ray incident surface of the X-ray transparent substrate. The X-ray sensor according to claim 1, comprising a film layer, an electron injection blocking layer, and an electron incident electrode. An X-ray source and an X-ray sensor disposed opposite to the X-ray source at a predetermined interval;
The X-ray diagnostic apparatus using the X-ray sensor as described in any one of Claim 1 to 4 as said X-ray sensor.

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