WO2013042415A1 - Radiographic moving image shooting device, method for setting region-of-interest for radiographic moving image shooting device, radioactive moving image shooting system, radiographic moving image shooting control program, and memory medium for radiographic moving image shooting control program - Google Patents

Radiographic moving image shooting device, method for setting region-of-interest for radiographic moving image shooting device, radioactive moving image shooting system, radiographic moving image shooting control program, and memory medium for radiographic moving image shooting control program Download PDF

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Publication number
WO2013042415A1
WO2013042415A1 PCT/JP2012/066049 JP2012066049W WO2013042415A1 WO 2013042415 A1 WO2013042415 A1 WO 2013042415A1 JP 2012066049 W JP2012066049 W JP 2012066049W WO 2013042415 A1 WO2013042415 A1 WO 2013042415A1
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Prior art keywords
radiation
moving image
region
interest
unit
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PCT/JP2012/066049
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French (fr)
Japanese (ja)
Inventor
北野 浩一
岩切 直人
大田 恭義
西納 直行
中津川 晴康
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富士フイルム株式会社
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Publication of WO2013042415A1 publication Critical patent/WO2013042415A1/en

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    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment
    • A61B6/46Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment with special arrangements for interfacing with the operator or the patient
    • A61B6/467Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment with special arrangements for interfacing with the operator or the patient characterised by special input means
    • A61B6/469Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment with special arrangements for interfacing with the operator or the patient characterised by special input means for selecting a region of interest [ROI]
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment
    • A61B6/48Diagnostic techniques
    • A61B6/486Diagnostic techniques involving generating temporal series of image data
    • A61B6/487Diagnostic techniques involving generating temporal series of image data involving fluoroscopy
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment
    • A61B6/54Control of apparatus or devices for radiation diagnosis
    • A61B6/542Control of apparatus or devices for radiation diagnosis involving control of exposure

Definitions

  • the present invention is directed to generating a moving image of a subject by continuously capturing still images obtained by exposing a subject to radiation and receiving a radiation amount passing through the subject with a radiation detector.
  • the present invention relates to a moving image capturing apparatus, a region of interest setting method for a radiation moving image capturing apparatus, a radiation image capturing system, a radiation moving image capturing control program, and a radiation moving image capturing control program storage medium.
  • radiation detectors such as FPD (Flat Panel Detector) that can arrange radiation sensitive layers on TFT (Thin Film Transistor) active matrix substrates and convert radiation dose into digital data (electrical signals) (referred to as “electronic cassette” etc.)
  • FPD Fluor Deposition Detector
  • TFT Thin Film Transistor
  • electrostatic cassette a radiation image capturing apparatus that captures a radiation image represented by the amount of radiation that has been exposed using this radiation detector has been put into practical use.
  • the radiation dose is, for example, interchangeably converted into a light emission amount and then converted into an electric signal, and then a direct conversion method in which the radiation dose is directly converted into an electric signal, and is selected as appropriate. Adopted.
  • the radiographic imaging apparatus As described above, it is considered to display a so-called moving image by continuously reproducing image information detected by a radiation detector at regular intervals. Note that the shorter the time interval, the better the continuity and the better the image quality as a moving image. However, the amount of image information is increased by using a general CCD or CMOS. It is the same as an imaging device (image sensor). In the radiographic image capturing apparatus, if the number of image frames to be captured increases, the radiation dose to the subject increases. Therefore, it is preferable to select an appropriate number of image frames.
  • the “appropriate number of image frames” refers to whether the movement of the imaging target (image in the region of interest (ROI) in the subject) is fast or slow, whether or not the change amount of the movement is important, etc. This is the number of image frames decided according to the purpose.
  • Japanese Patent Application Laid-Open No. 2010-273434 discloses an X-ray diagnostic imaging apparatus that displays a fluoroscopic image of a contrasted blood vessel and a DA (Digital Angiography) image.
  • Japanese Patent Laid-Open No. 9-266901 discloses an image processing condition setting device for radiographic images.
  • Japanese Patent Application Laid-Open No. 2010-27383 discloses an X-ray diagnostic imaging apparatus that performs ABC control based on an image level in a region of interest by appropriately canceling ABC control according to a user operation, and the X-ray condition at that time A technique that can fix the above is disclosed.
  • the radiation dose emitted from the radiation generating device may be reduced.
  • the ABC control is executed before the region of interest is determined.
  • the radiation dose may be controlled to increase in spite of the so-called pre-photographing image.
  • Japanese Patent Application Laid-Open No. 2010-273834 describes releasing the ABC control.
  • the timing for releasing the ABC control is when imaging a region that directly detects X-rays. The effects are different.
  • Japanese Patent Application Laid-Open No. 2010-273434 releases ABC control in response to a user operation, and there is no causal relationship between ABC control and a region of interest.
  • the present invention provides a radiological moving image capturing apparatus and a radiological moving image capable of reducing the radiation exposure dose to a subject without adversely affecting the identification of a region of interest when mainly capturing a moving image.
  • An imaging device region-of-interest setting method, a radiographic imaging system, a radiographic video imaging control program, and a radiographic video imaging control program storage medium are provided.
  • a radiological moving image capturing apparatus wherein a radiation having a set steady range of radiation energy is exposed from a radiation exposure unit that exposes radiation toward a subject, and the subject A radiation image capturing unit that receives a radiation dose that has passed through the specimen with a radiation detector having a plurality of pixels and outputs a gradation signal corresponding to the radiation dose received for each pixel, and a gradation from the radiation image capturing unit A signal is acquired, the gradation signal is read under a predetermined dynamic range, and still image information is generated for each frame, and the moving image of the subject is captured by continuously capturing the still image.
  • a moving image information generation unit to be generated; a control unit that performs feedback control of a set value of radiation energy of the radiation that is emitted from the radiation exposure unit at a predetermined control cycle; and a feedback by the control unit.
  • the control is prohibited, and the exposure amount of the subject is executed in a state where the exposure amount is suppressed from the exposure amount due to the radiation energy in the steady range, and a part of the image generated by the moving image information generation unit is set as a region of interest.
  • a region of interest setting unit to be set.
  • the radiation exposure unit exposes radiation of radiation energy in a set steady range toward the subject.
  • the radiation amount exposed from the radiation exposure unit and passed through the subject is received by a radiation detector having a plurality of pixels, and a gradation signal corresponding to the radiation amount received for each pixel Is output.
  • the moving image information generation unit acquires a gradation signal from the radiographic image capturing unit, reads the gradation signal under a predetermined dynamic range, generates still image information for each frame, and A moving image of the subject is generated by continuously capturing images.
  • control unit feedback-controls the set value of the radiation energy of the radiation exposed from the radiation exposure unit at a predetermined control cycle.
  • the region of interest setting unit sets the region of interest from the moving images to be photographed.
  • the region-of-interest setting unit prohibits feedback control by the control unit and sets a part of the image as the region of interest in a state where the exposure amount of the subject is suppressed from the steady range.
  • the exposure dose of the subject can be suppressed from the steady range. Moreover, the state which was suppressed can be maintained by prohibiting feedback control.
  • the suppression of the said exposure amount may be making the radiation energy instruct
  • the exposure dose to the subject can be reduced by making the radiation energy of the radiation source itself lower than the steady range.
  • the suppression of the exposure dose may be a frame rate lower than that in a steady state.
  • the frame rate in the radiation detector By making the frame rate in the radiation detector lower than that in the steady state, it is possible to reliably generate a still image that is the basis of a moving image even if the necessary radiation dose is reduced accordingly.
  • the radiation dose itself detected by each pixel can be maintained by synchronizing the radiation emitted from the radiation exposure unit with the frame rate and outputting it intermittently. A signal can be obtained.
  • the exposure dose may be suppressed by disposing a filter for cutting radiation between the radiation exposure unit and the subject.
  • a part of the radiation may be physically shielded by interposing a filter for cutting the radiation between the radiation exposure unit and the subject.
  • the filter includes a so-called diaphragm mechanism that can be installed on an exposure surface of the radiation exposure unit.
  • the rate of change of the image information with respect to the gradation signal which is a parameter for compression of the dynamic range, is being feedback controlled. May be larger.
  • the feedback control is prohibited in order to suppress the exposure dose of the subject from the steady range, naturally the control to increase the radiation energy cannot be performed. In such a situation, for example, if the radiation energy instructed to the radiation exposure unit is lower than the steady range, the amount of radiation detected for each pixel is reduced, and a gradation signal is appropriately obtained. It may not be possible.
  • the dynamic range compression parameter is made larger than the dynamic range compression parameter during feedback control.
  • the dynamic range compression parameter is the rate of change of the image information with respect to the gradation signal.
  • the radiation dose received by the radiation detector is small because the radiation energy is low, and the gradation signal tends to be biased toward the low level. Tonal change (density change) is low.
  • Appropriate image information can be obtained from a so-called underimage by increasing the dynamic range compression parameter, that is, the rate of change of the image information with respect to the gradation signal, in accordance with this biased region.
  • the target of feedback control by the control unit may be an image in the region of interest.
  • the radiation dose can be adjusted separately inside and outside the region of interest, feedback correction is performed so that appropriate radiation energy is obtained within the region of interest, and the radiation dose is reduced outside the region of interest, thereby exposing the subject.
  • the amount of radiation emitted can be reduced.
  • the exposure surface of the radiation exposure unit is partitioned and controlled independently, or between the radiation exposure unit and the subject
  • a moving image may be made to follow the movement of the region of interest.
  • the second aspect of the present invention is a region-of-interest setting method, in which radiation is irradiated toward a subject with radiation energy that is less than the exposure amount due to radiation energy in a steady range and passes through the subject.
  • the amount is received by a radiation detector having a plurality of pixels, and still image information for each frame is generated based on a gradation signal corresponding to the amount of radiation received for each pixel, and the still image is continuously displayed.
  • To generate a moving image of the subject set a part of the generated image as a region of interest, and after setting the region of interest, release the suppression of the radiation energy and perform predetermined control
  • processing for feedback control of the set value of the radiation energy of the radiation to be exposed is started.
  • the second aspect as a normal moving image capturing procedure, radiation having radiation energy in a set steady range is exposed toward the subject, and is exposed and passed through the subject.
  • the amount is received by a radiation detector having a plurality of pixels, a gradation signal corresponding to the amount of radiation received for each pixel is read under a predetermined dynamic range, and still image information for each frame is generated, A moving image of the subject is generated by continuously capturing still images.
  • control unit feedback-controls the set value of the radiation energy of the radiation exposed from the radiation exposure unit at a predetermined control cycle.
  • the region of interest is set from the moving images to be shot.
  • feedback control is prohibited and a part of the image is set as the region of interest while the exposure dose of the subject is suppressed from the steady range.
  • the exposure dose of the subject can be suppressed from the steady range. Moreover, the state which was suppressed can be maintained by prohibiting feedback control.
  • the suppression of the said exposure amount may be making the radiation energy instruct
  • the exposure dose to the subject can be reduced by making the radiation energy of the radiation source itself lower than the steady range.
  • the suppression of the exposure dose may be a frame rate lower than that in a steady state.
  • the frame rate in the radiation detector By making the frame rate in the radiation detector lower than that in the steady state, it is possible to reliably generate a still image that is the basis of a moving image even if the necessary radiation dose is reduced accordingly.
  • the radiation dose itself detected by each pixel can be maintained by synchronizing the radiation emitted from the radiation exposure unit with the frame rate and outputting it intermittently. A signal can be obtained.
  • the dynamic range compression parameter for reading the gradation signal may be used as the dynamic range compression parameter during the feedback control.
  • the feedback control is prohibited in order to suppress the exposure dose of the subject from the steady range, naturally the control to increase the radiation energy cannot be performed. In such a situation, for example, if the radiation energy instructed to the radiation exposure unit is lower than the steady range, the amount of radiation detected for each pixel is reduced, and a gradation signal is appropriately obtained. It may not be possible.
  • the dynamic range compression parameter is made larger than the dynamic range compression parameter during feedback control.
  • the dynamic range compression parameter is the rate of change of the image information with respect to the gradation signal.
  • the radiation dose received by the radiation detector is small because the radiation energy is low, and the gradation signal tends to be biased toward the low level. Tonal change (density change) is low.
  • Appropriate image information can be obtained from a so-called underimage by increasing the dynamic range compression parameter, that is, the rate of change of the image information with respect to the gradation signal, in accordance with this biased region.
  • a third aspect of the present invention is a radiographic imaging system, and performs input and browsing of diagnostic information and facility reservation, and radiographic video imaging request and imaging reservation with the radiographic video imaging apparatus of the first aspect.
  • the third aspect it can be applied as a system for managing information such as medical appointment reservations and diagnostic records, particularly in a radiology department in a hospital, and can be a part of a hospital information system.
  • a radiation moving image photographing control program that causes a computer to function as a moving image information generation unit, a control unit, and a region of interest setting unit of the radiation moving image photographing apparatus according to the first aspect.
  • the radiological moving image capturing control program can be stored in a storage medium.
  • the fifth aspect of the present invention is a persistent computer-readable storage medium storing a program for causing a computer to execute a radiation moving image capturing process, wherein the radiation moving image capturing process is directed toward a subject.
  • a still image information for each frame is generated based on a gradation signal corresponding to the amount of radiation received by the camera, and a moving image of the subject is generated by continuously capturing the still images, and the generated image Is set as a region of interest, and after setting the region of interest, the radiation energy is released at a predetermined control period after the suppression of the radiation energy is released. It includes initiating a process of feedback control of the set value.
  • each aspect of the present invention has an excellent effect that the radiation exposure dose to the subject can be reduced without adversely affecting the identification of the region of interest when mainly capturing moving images.
  • (A) is a histogram of the QL value generated from the electric conversion signal when the radiation dose is lower than that at the time of steady setting when ROI is set (same as FIG. 10 (B)), and (B) is in FIG. 11 (A). It is a histogram of the QL value when the dynamic range is compressed.
  • FIG. 1 is a schematic configuration diagram of a radiation information system 10 (hereinafter referred to as “RIS” (Radiology Information System)) according to the present embodiment.
  • the RIS 10 can capture a moving image in addition to a still image.
  • the definition of a moving image means that still images are displayed one after another at a high speed and recognized as a moving image.
  • the still image is photographed, converted into an electric signal, transmitted, and the still image is converted from the electric signal.
  • the process of replaying is repeated at high speed. Accordingly, the so-called “frame advance” in which the same area (part or all) is photographed a plurality of times within a predetermined time and continuously reproduced in accordance with the degree of the “high speed” is also included in the moving image.
  • frame advance in which the same area (part or all) is photographed a plurality of times within a predetermined time and continuously reproduced in accordance with the degree of the “high speed” is also included in the moving image.
  • the RIS 10 is a system for managing information such as medical appointment reservations and diagnosis records in the radiology department, and constitutes a part of a hospital information system (hereinafter referred to as “HIS” (Hospital Information System)).
  • HIS Hospital Information System
  • the RIS 10 includes a plurality of radiographic imaging systems installed individually in a plurality of imaging request terminal devices (hereinafter referred to as “terminal devices”) 12, a RIS server 14, and a radiographic room (or operating room) in a hospital.
  • imaging system which are connected to a hospital network 18 including a wired or wireless LAN (Local Area Network).
  • the hospital network 18 is connected to an HIS server (not shown) that manages the entire HIS.
  • the radiographic image capturing system 16 may be a single unit or three or more facilities. In FIG. 1, the radiographic image capturing system 16 is installed for each radiographing room. An imaging system 16 may be arranged.
  • the terminal device 12 is used by doctors and radiographers to input and view diagnostic information and facility reservations, and radiographic image capturing requests and imaging reservations are performed via the terminal device 12.
  • Each terminal device 12 includes a personal computer having a display device, and is capable of mutual communication via the RIS server 14 and the hospital network 18.
  • the RIS server 14 receives an imaging request from each terminal device 12 and manages a radiographic imaging schedule in the imaging system 16, and includes a database 14A.
  • the database 14A includes attribute information (name, sex, date of birth, age, blood type, weight, patient ID (Identification), etc.) of a patient (which may be referred to as “subject's subject,“ subject ”)”, Patient history such as medical history, medical history, radiation images taken in the past, identification number (ID information) of electronic cassette 20 (model information) used in imaging system 16, model, size, sensitivity, use start date, use Information on the electronic cassette 20 such as the number of times, and environment information indicating an environment in which a radiographic image is captured using the electronic cassette 20, that is, an environment in which the electronic cassette 20 is used (for example, a radiography room or an operating room) are included. .
  • medical-related data managed by medical institutions is stored almost permanently, and when necessary, a system (sometimes referred to as a “medical cloud”) that instantly retrieves data from the required location can be used outside the hospital.
  • a system sometimes referred to as a “medical cloud” that instantly retrieves data from the required location can be used outside the hospital.
  • Past personal information of the patient (subject) may be obtained from the server.
  • the imaging system 16 captures a radiographic image by an operation of a doctor or a radiographer according to an instruction from the RIS server 14.
  • the imaging system 16 exposes the subject to the radiation X having a dose according to the exposure conditions from the radiation exposure source 22A that exposes the radiation X under the control of the radiation exposure control unit 22 (see FIG. 4).
  • a radiation generating device 24 that emits radiation
  • a radiation detector 26 that generates radiation by absorbing the radiation X transmitted through the imaging target region of the subject and generates image information indicating a radiation image based on the amount of the generated charge ( 3), a cradle 28 for charging a battery built in the electronic cassette 20, and a console 30 for controlling the electronic cassette 20 and the radiation generator 24.
  • the console 30 acquires various types of information included in the database 14A from the RIS server 14 and stores them in an HDD 88 (see FIG. 4) described later. If necessary, the console 30 uses the information to store the electronic cassette 20 and the radiation generator 24. Take control.
  • FIG. 2 shows an example of the arrangement state of each device in the radiation imaging room 32 of the imaging system 16 according to the present embodiment.
  • the radiation imaging room 32 there are a standing table 34 used when performing radiography in a standing position and a prone table 36 used when performing radiation imaging in a lying position.
  • the space in front of the standing table 34 is set as the imaging position of the subject 38 when performing radiography in the standing position, and the upper space of the prone table 36 is used in performing radiography in the prone position. This is the imaging position of the subject 40.
  • the standing table 34 is provided with a holding unit 42 that holds the electronic cassette 20, and the electronic cassette 20 is held by the holding unit 42 when a radiographic image is taken in the standing position.
  • a holding unit 44 that holds the electronic cassette 20 is provided in the lying position table 36, and the electronic cassette 20 is held by the holding unit 44 when a radiographic image is taken in the lying position.
  • the radiation exposure source 22A is installed in a horizontal position in order to enable radiography in the standing position and in the prone position by the radiation from the single radiation exposure source 22A.
  • Support movement that can rotate around the axis (in the direction of arrow A in FIG. 2), move in the vertical direction (in the direction of arrow B in FIG. 2), and further move in the horizontal direction (in the direction of arrow C in FIG. 2).
  • a mechanism 46 is provided.
  • a drive source for moving (including turning) the radiation exposure source 22A in the directions of arrows A to C in FIG. 2 is built in the support moving mechanism 46, and is not shown here.
  • the cradle 28 is formed with an accommodating portion 28A capable of accommodating the electronic cassette 20.
  • the built-in battery is charged in a state of being accommodated in the accommodating portion 28A of the cradle 28.
  • the electronic cassette 20 is taken out of the cradle 28 by a radiographer or the like, and the photographing posture is established. If it is in the upright position, it is held in the holding part 42 of the standing table 34, and if it is in the upright position, it is held in the holding part 44 of the standing table 36.
  • various kinds of information are transmitted by wireless communication between the radiation generator 24 and the console 30 and between the electronic cassette 20 and the console 30. Send and receive (details will be described later).
  • the electronic cassette 20 is not used only in the state of being held by the holding portion 42 of the standing base 34 or the holding portion 44 of the prone position base 36. When photographing, it can be used in a state where it is not held by the holding unit.
  • FIG. 3 is a schematic cross-sectional view schematically showing the configuration of the three pixel portions of the radiation detector 26 provided in the electronic cassette 20.
  • the radiation detector 26 includes a signal output unit 52, a sensor unit 54 (TFT substrate 74), and a scintillator 56 that are sequentially stacked on an insulating substrate 50.
  • a pixel group of the TFT substrate 74 is provided by the sensor unit 54. That is, the plurality of pixels are arranged in a matrix on the substrate 50, and the signal output unit 52 and the sensor unit 54 in each pixel are configured to overlap each other.
  • An insulating film 53 is interposed between the signal output unit 52 and the sensor unit 54.
  • the scintillator 56 is formed on the sensor unit 54 via a transparent insulating film 58, and forms a phosphor that emits light by converting radiation incident from above (opposite side of the substrate 50) or below into light. It is what. Providing such a scintillator 56 absorbs radiation transmitted through the subject and emits light.
  • the wavelength range of light emitted by the scintillator 56 is preferably in the visible light range (wavelength 360 nm to 830 nm), and in order to enable monochrome imaging by the radiation detector 26, the wavelength range of green is included. Is more preferable.
  • the phosphor used in the scintillator 56 preferably contains cesium iodide (CsI) when imaging using X-rays as radiation, and has an emission spectrum of 400 nm to 700 nm upon X-ray exposure. It is particularly preferred to use some CsI (Tl) (cesium iodide with thallium added). Note that the emission peak wavelength of CsI (Tl) in the visible light region is 565 nm.
  • CsI cesium iodide
  • the sensor unit 54 includes an upper electrode 60, a lower electrode 62, and a photoelectric conversion film 64 disposed between the upper and lower electrodes.
  • the photoelectric conversion film 64 absorbs light emitted from the scintillator 56 and generates electric charges. It is composed of an organic photoelectric conversion material.
  • the upper electrode 60 Since it is necessary for the upper electrode 60 to cause the light generated by the scintillator 56 to enter the photoelectric conversion film 64, it is preferable that the upper electrode 60 be made of a conductive material that is transparent at least with respect to the emission wavelength of the scintillator 56. It is preferable to use a transparent conductive oxide (TCO “Transparent Conductive Oxide”) having a high transmittance for visible light and a low resistance value. Although a metal thin film such as Au can be used as the upper electrode 60, the TCO is preferable because it tends to increase the resistance when it is desired to obtain a transmittance of 90% or more.
  • TCO Transparent Conductive Oxide
  • the upper electrode 60 may have a single configuration common to all pixels, or may be divided for each pixel.
  • the photoelectric conversion film 64 includes an organic photoelectric conversion material, absorbs light emitted from the scintillator 56, and generates electric charge according to the absorbed light.
  • the photoelectric conversion film 64 including the organic photoelectric conversion material has a sharp absorption spectrum in the visible region, and electromagnetic waves other than light emitted by the scintillator 56 are hardly absorbed by the photoelectric conversion film 64, and X-rays are obtained.
  • the noise generated by the radiation such as being absorbed by the photoelectric conversion film 64 can be effectively suppressed.
  • the organic photoelectric conversion material constituting the photoelectric conversion film 64 is preferably such that its absorption peak wavelength is closer to the emission peak wavelength of the scintillator 56 in order to absorb light emitted by the scintillator 56 most efficiently.
  • the absorption peak wavelength of the organic photoelectric conversion material matches the emission peak wavelength of the scintillator 56, but if the difference between the two is small, the light emitted from the scintillator 56 can be sufficiently absorbed.
  • the difference between the absorption peak wavelength of the organic photoelectric conversion material and the emission peak wavelength with respect to the radiation of the scintillator 56 is preferably within 10 nm, and more preferably within 5 nm.
  • Examples of the organic photoelectric conversion material that can satisfy such conditions include quinacridone organic compounds and phthalocyanine organic compounds.
  • quinacridone organic compounds since the absorption peak wavelength in the visible region of quinacridone is 560 nm, if quinacridone is used as the organic photoelectric conversion material and CsI (Tl) is used as the material of the scintillator 56, the difference in peak wavelength can be made within 5 nm. Thus, the amount of charge generated in the photoelectric conversion film 64 can be substantially maximized.
  • the sensor unit 54 constituting each pixel only needs to include at least the lower electrode 62, the photoelectric conversion film 64, and the upper electrode 60.
  • the electron blocking film 66 and the hole blocking film are used. It is preferable to provide at least one of 68, and it is more preferable to provide both.
  • the electron blocking film 66 can be provided between the lower electrode 62 and the photoelectric conversion film 64.
  • a bias voltage is applied between the lower electrode 62 and the upper electrode 60, electrons are transferred from the lower electrode 62 to the photoelectric conversion film 64. It is possible to suppress the dark current from increasing due to the injection of.
  • An electron donating organic material can be used for the electron blocking film 66.
  • the hole blocking film 68 can be provided between the photoelectric conversion film 64 and the upper electrode 60. When a bias voltage is applied between the lower electrode 62 and the upper electrode 60, the hole blocking film 68 is transferred from the upper electrode 60 to the photoelectric conversion film 64. It is possible to suppress the increase in dark current due to the injection of holes.
  • An electron-accepting organic material can be used for the hole blocking film 68.
  • the signal output unit 52 corresponds to the lower electrode 62, a capacitor 70 that accumulates the charges transferred to the lower electrode 62, and a field effect thin film transistor (Thin) that converts the charges accumulated in the capacitor 70 into an electric signal and outputs the electric signal.
  • Thin field effect thin film transistor
  • (Thin) 72 is formed.
  • the region in which the capacitor 70 and the thin film transistor 72 are formed has a portion that overlaps the lower electrode 62 in plan view. With this configuration, the signal output unit 52 and the sensor unit 54 in each pixel are thick. There will be overlap in the vertical direction. In order to minimize the plane area of the radiation detector 26 (pixel), it is desirable that the region where the capacitor 70 and the thin film transistor 72 are formed is completely covered with the lower electrode 62.
  • FIG. 4 is a control block diagram of the imaging system 16 according to the present embodiment.
  • the console 30 functions as a server computer, and includes a display 80 for displaying an operation menu, a captured radiographic image, and the like, and an operation panel 82 for inputting various information and operation instructions. I have.
  • the console 30 includes a CPU 84 that controls the operation of the entire apparatus, a ROM 86 that stores various programs including a control program in advance, a RAM 87 that temporarily stores various data, and various data.
  • An HDD (Hard Disk Drive) 88 that stores and holds, a display driver 92 that controls display of various types of information on the display 80, and an operation input detector 90 that detects an operation state of the operation panel 82 are provided. .
  • the console 30 transmits and receives various information such as an exposure condition described later between the image processing device 23 and the radiation generation device 24 by wireless communication, and various types of image data and the like with the electronic cassette 20.
  • An I / F (for example, a wireless communication unit) 96 and an I / O 94 that transmit and receive information are provided.
  • the CPU 84, ROM 86, RAM 87, HDD 88, display driver 92, operation input detection unit 90, I / O 94, and wireless communication unit 96 are connected to each other via a bus 98 such as a system bus or a control bus. Therefore, the CPU 84 can access the ROM 86, RAM 87, and HDD 88, controls display of various information on the display 80 via the display driver 92, and the radiation generator 24 via the wireless communication unit 96. Control of transmission and reception of various types of information with the electronic cassette 20 can be performed. Further, the CPU 84 can grasp the operation state of the user with respect to the operation panel 82 via the operation input detection unit 90.
  • the image processing apparatus 23 includes an I / F (for example, a wireless communication unit) 100 that transmits and receives various types of information such as an exposure condition to and from the console 30, and the electronic cassette 20 and the radiation generation apparatus based on the exposure condition. 24, an image processing control unit 102 for controlling 24.
  • the radiation generator 24 includes a radiation exposure control unit 22 that controls radiation exposure from the radiation exposure source 22A.
  • the image processing control unit 102 includes a system control unit 104, a panel control unit 106, and an image processing control unit 108, and exchanges information with each other via a bus 110.
  • the panel control unit 106 receives information from the electronic cassette 20 wirelessly or by wire, and the image processing control unit 108 performs image processing.
  • the system control unit 104 receives information such as a tube voltage and a tube current as an exposure condition from the console 30 and, based on the received exposure condition, the radiation X from the radiation exposure source 22A of the radiation exposure control unit 22. Control to expose.
  • region to be noticed region of interest
  • ROI region of interest
  • the imaging system 16 has a function of automatically setting a region of interest based on the operation state of the captured image. Control for setting the region of interest is executed.
  • appropriate image information is obtained by performing feedback correction on the radiation dose of radiation exposed to the subject under the control of ABC “Auto Brightness Control”.
  • the principle of ABC control is that radiation exposure is performed so that the average value of one frame of the QL value generated based on the gradation signal received from the electronic cassette 20 converges to a predetermined threshold value (reference value). This is for adjusting the amount of radiation exposed from the radiation source 22A, for example, the same as the light amount adjustment by a digital camera or a movie camera.
  • the completion of the ROI setting is before the so-called main imaging, and particularly in the case of moving image shooting, it is preferable to suppress the radiation exposure dose to the subject until the ROI is determined after the ROI has been set.
  • a change in ROI during the main imaging for example, a change for tracking the distal end portion of the catheter tube, etc. does not need to be concerned about radiation exposure because ABC control is stable.
  • FIG. 5 is a block diagram specialized in a control system for radiographic image capturing (including ROI setting) in the imaging system 16 (mainly the console 16, the image processing device 23, and the radiation generating device 24).
  • this block diagram categorizes radiographic image capturing control by function, and does not limit the hardware configuration. That is, each functional unit (radiation dose adjustment unit 120, gradation signal analysis unit 124, dynamic range adjustment unit 126, still image generation unit 128, moving image editing unit 130, average QL value described in FIG. 5 described below.
  • the calculation unit 132, the ABC control unit 134, the reference QL value memory 136, the region of interest setting unit 138, and the exposure control unit 140 before ROI determination are arranged in any of the console 30, the image processing device 23, and the radiation generation device 24. Also good.
  • the radiation exposure control unit 22 exposes radiation from the radiation exposure source 22A based on the radiation dose adjusted by the radiation dose adjustment unit 120.
  • the radiation dose adjustment unit 120 adjusts the output radiation dose (energy), and details will be described later.
  • the radiation exposed from the radiation exposure source 22A passes through the subject 40 lying on the prone table 36 and reaches the radiation detector 26 (see FIG. 3) of the electronic cassette 20.
  • the radiation detector 26 the phosphor film 56 (see FIG. 3) emits light having a light amount corresponding to the radiation amount and is photoelectrically converted by the TFT substrate 74.
  • the TFT substrate 74 of the electronic cassette 20 is connected to the signal acquisition unit 122.
  • the signal acquisition unit 122 acquires a signal photoelectrically converted based on the radiation exposed from the radiation exposure source 22 ⁇ / b> A and sends it to the gradation signal analysis unit 124.
  • the photoelectric conversion signal may be an analog signal or may be converted into a digital signal by the control unit in the electronic cassette 20.
  • a dynamic range adjustment unit 126 is connected to the gradation signal analysis unit 124.
  • the compression parameter of the dynamic range received from the dynamic range adjustment unit 126 (hereinafter, referred to as "compression ratio", the steady state is the compression ratio DR N.)
  • compression ratio the compression parameter of the dynamic range received from the dynamic range adjustment unit 126
  • the QL value is the gradation signal itself (raw data), it is not the gradation signal itself, but, for example, the capacitor 70 (see FIG. 3) of the electronic cassette 20 or other circuit system capacitance.
  • a value after correcting the noise component may be used as the QL value.
  • the gradation signal analysis unit 124 is connected to the still image generation unit 128.
  • the gradation signal analysis unit 124 sequentially transmits the gradation signals for one frame to the still image generation unit 128 when they are ready.
  • the still image generation unit 128 generates image data for each frame based on the received gradation signal.
  • the photoelectric conversion signal itself sent from the electronic cassette 20 is different between the case of moving image shooting and the case of still image shooting.
  • the transfer speed is set to be different.
  • a binning process is performed to give priority.
  • image data based on the maximum number of pixels on the TFT substrate 74 is generated in order to prioritize image quality.
  • the still image generation unit 128 is connected to the moving image editing unit 130.
  • the moving image editing unit 130 combines the image data for each frame sequentially transmitted from the still image generating unit 128 to edit the moving image.
  • the edited moving image is displayed on the display 80 via the display driver 92.
  • the still image generation unit 128 is connected to the display driver 92, and can display a still image on the display 80.
  • the moving image editing unit 130 is connected to the average QL value calculation unit 132.
  • the average QL value calculation unit 132 calculates the average value of the QL values of each frame (or one frame appropriately extracted) of the moving image.
  • the calculation result in the average QL value calculation unit 132 is sent to the ABC control unit 134.
  • a reference QL value memory 136 is connected to the ABC control unit 134.
  • the ABC control unit 134 compares the QL average value received from the average QL value calculation unit 132 with the reference QL value received from the reference QL value memory 136, and converges the QL average value to the reference QL value.
  • Correction information ⁇ X is generated. This correction information ⁇ X is applied as a correction coefficient for increasing or decreasing the radiation dose (energy) exposed from the radiation exposure source 22A.
  • the correction information ⁇ X generated by the ABC control unit 134 is sent to the radiation dose adjustment unit 120.
  • the radiation dose XN is increased or decreased (X N ⁇ X N ⁇ ⁇ X).
  • Radiation dose adjustment unit 120 stores the initial value of the radiation amount X N, when there is exposure instructed exposure from the initial value is started.
  • the photoelectric conversion signal that is the basis for generating the moving image can be within an appropriate range without excess or deficiency for obtaining the gradation signal. This means that it is a region where the rate of change in the characteristic diagram showing the correlation between the photoelectric conversion signal and the image density is large (for example, an intermediate region of the ⁇ curve in the case of a photosensitive material).
  • the coefficient of the correction information [Delta] X to the power of (removal) calculation may be acceleration (deceleration) calculated coefficients (X N ⁇ X N + ⁇ X N) .
  • the moving image editing unit 130 is connected to the region of interest setting unit 138.
  • This region of interest setting unit 138 sets a region of interest (ROI) based on the moving image data received from the moving image editing unit 130.
  • ROI region of interest
  • a general method is a method of surrounding pixels having a pixel value equal to or greater than a certain value, and is suitable for surrounding an organ or a lesion where radioactivity is accumulated.
  • an ROI is defined in advance in a standard image and is matched with a target image. Furthermore, in the case of a moving image, a portion with a large amount of change may be extracted.
  • the region-of-interest setting unit 138 When setting the ROI, the region-of-interest setting unit 138 outputs at least a start signal indicating the start of ROI setting and a completion signal indicating the completion of setting to the exposure control unit 140 before ROI determination.
  • the pre-ROI determination exposure control unit 140 is connected to the radiation dose adjustment unit 120, the ABC control unit 134, and the dynamic range adjustment unit 126, respectively.
  • the control prohibition signal for instructing prohibition of the ABC control is output from the pre-ROI determination exposure control unit 140 to the ABC control unit 134.
  • the result of the histogram analysis of the photoelectric conversion signal in the modulation signal analysis unit 124 is a part of the set dynamic range (region with a low QL value). ) Only.
  • a dynamic range compression ratio instruction signal which is an instruction for setting the compression ratio DR ROI for setting a high ROI, is output (DR ROI > DR N ).
  • the result of the histogram analysis of the photoelectric conversion signal covers the entire dynamic range.
  • the amount of radiation exposure from the radiation exposure source 22A (energy) lowered (from dose X N to radiation amount X ROI), and, correspondingly, which were low, the dynamic by increasing the compression ratio of the range (from the compression ratio DR N to DR ROI), and radiation exposure reduction of the subject to radiation amount decreases, it is possible to achieve both ROI setting precision.
  • the setting of the ROI in the ROI setting unit 130 is completed, completion signal that is sent to ROI vested exposure control unit 140, the radiation amount adjuster 120, the radiation amount is set to an initial value X N in the dynamic range adjustment unit 126, the compression ratio is set to DR N. Also, ABC control by the ABC control unit 134 can be executed.
  • FIG. 6 is a flowchart showing the radiographic imaging preparation control routine.
  • step 200 it is determined whether or not there has been a shooting instruction on the console 30, and if a negative determination is made, this routine ends. If an affirmative determination is made, the routine proceeds to step 202.
  • step 202 an initial information input screen is displayed. That is, the display driver 92 is controlled to display a predetermined initial information input screen on the display 80, and the process proceeds to step 204.
  • step 204 input of predetermined information is waited.
  • the name of the subject who will take a radiographic image, the part to be imaged, the posture at the time of radiography, and the exposure condition of the radiographic X at the time of radiography (in this embodiment, the radiation X is exposed Message for prompting the input of the tube voltage and tube current) and an input area for such information are displayed.
  • the photographer When the initial information input screen is displayed on the display 80, the photographer displays the name of the subject to be imaged, the region to be imaged, the posture at the time of imaging, and the exposure conditions in the corresponding input areas. Input via 82.
  • the radiographer enters the radiography room 32 together with the subject.
  • the radio cassette 20A is supported while the electronic cassette 20 is held in the holding unit 44 of the corresponding prone position table 36.
  • the subject is positioned (positioned) at a predetermined imaging position.
  • the subject and the electronic cassette 20 are ready to capture the imaging target site.
  • the radiation exposure source 22A is positioned (positioned).
  • step 204 is affirmative and the process proceeds to step 206.
  • the negative determination in step 204 is an infinite loop, but it may be forcibly terminated by operating a cancel button provided on the operation panel 82.
  • step 206 information input on the initial information input screen from the console 30 (hereinafter referred to as “initial information”) is transmitted to the electronic cassette 20 via the wireless communication unit 96, and then the process proceeds to the next step 208.
  • the exposure condition included in the initial information is transmitted to the radiation generator 24 via the wireless communication unit 96 to set the exposure condition.
  • the image processing control unit 102 of the radiation generator 24 prepares for exposure under the received exposure conditions.
  • step 210 the ABC control unit 134 instructs activation of ABC control, and then the process proceeds to step 212, and instruction information for instructing the start of radiation exposure is sent to the radiation generator 24 via the wireless communication unit 96. And the routine ends.
  • the details of the ABC control in step 210 will be described later using the flowchart of FIG.
  • step 250 it is determined whether or not the radiation generator 24 (or system control unit 104) has issued an exposure start instruction. If a negative determination is made, this routine ends. If an affirmative determination is made, the routine proceeds to step 252. Transition.
  • step 252 the ROI setting unit 138 executes region-of-interest setting control, and when the region-of-interest setting ends, the process proceeds to step 254. Details of the region-of-interest setting control in step 252 will be described later using the flowchart of FIG.
  • step 254 a steady state dose by the radiation amount adjuster 120 reads out the (initial value) X N, then the routine proceeds to step 256, radiation exposure control unit 22, the radiation generator 24 Starts emission of radiation X from the radiation exposure source 22A at a tube voltage and a tube current according to the exposure conditions received from the console 30.
  • the radiation X emitted from the radiation exposure source 22A reaches the electronic cassette 20 after passing through the subject.
  • the currently stored radiation dose correction information is read out.
  • This radiation dose correction information is generated by ABC control and is stored as a correction coefficient ⁇ X.
  • the ABC control unit 134 executes correction processing based on ABC control. That is, based on the gradation signal (QL value) obtained from the electronic cassette 20, an average value of the QL values of the region of interest image is calculated, and the average value of the QL values is compared with a predetermined threshold value. The radiation dose is feedback controlled so as to converge to the threshold value.
  • step 262 moving image editing processing is executed in the moving image editing unit 130, and the edited moving image is displayed on the display 80 in step 264 (image display processing).
  • step 266 image data (moving image data) is transmitted to the RIS server 14 (see FIG. 1) via the in-hospital network 18, and the process proceeds to step 268.
  • step 268 it is determined whether or not an instruction to end imaging is given on the console 30, and if an affirmative determination is made, exposure is terminated in step 270 and the radiographic image capturing control program is terminated.
  • the corrected image data transmitted to the RIS server 14 is stored in the database 14A, so that a doctor can perform radiogram image interpretation and diagnosis.
  • step 210 of FIG. 6 the flow of ABC control that is instructed and started in step 210 of FIG. 6 will be described with reference to FIG. Note that the ABC control routine of FIG. 8 may be executed independently of the flowcharts of FIGS.
  • step 300 it is determined in the ABC control unit whether or not the exposure control after ROI determination is being performed. This is determined based on an ABC control prohibition instruction in Step 320 and an ABC control prohibition release instruction in Step 338, which will be described later.
  • step 300 If a negative determination is made in step 300, it is determined that ROI is being set, and this routine ends. That is, ABC control is not executed.
  • step 300 the dynamic range compression ratio set in the compression ratio DR N in the steady state and proceeds to step 302, then captures the image data and proceeds to step 304, it proceeds to step 306 To do.
  • step 306 the average QL value is calculated from the captured image data, and then the process proceeds to step 308 to read the reference QL value.
  • the average QL value from the captured image data is compared with the read reference QL value to determine whether correction is possible, and the process proceeds to step 312.
  • the determination as to whether correction is possible may be a so-called on / off determination in which a predetermined amount of correction is performed if the difference is greater than or equal to a predetermined value and no correction is made if the difference is less than a predetermined value.
  • the solution of the calculation by a predetermined arithmetic expression (for example, arithmetic expression based on PID control etc.) may be sufficient.
  • step 312 correction information ⁇ X of the radiation dose X ROI is generated based on the comparison and determination results in step 310, and then the process proceeds to step 314 to store the correction information ⁇ X generated in step 312. The routine ends.
  • FIG. 9 is a flowchart showing a region-of-interest setting control routine executed in step 252 of FIG.
  • the ROI setting unit 138 outputs a start signal to the exposure control unit 140 before ROI determination.
  • step 320 first, the pre-ROI confirmation exposure control unit 140 instructs the ABC control unit to prohibit ABC control.
  • the radiation dose exposed from the radiation exposure source 22A is constant without feedback control.
  • the exposure control unit 140 before ROI determination reads the region-of-interest setting radiation dose X ROI .
  • This region-of-interest setting radiation dose X ROI is lower than the steady-state radiation dose N (X ROI ⁇ X N ).
  • the ROI pre-determination exposure control unit 140 reads the dynamic range compression rate DR ROI when the region of interest is set.
  • This region-of-interest setting dynamic range compression rate DR ROI is higher than a predetermined dynamic range compression rate DR N (hereinafter referred to as “steady-state dynamic range DR N ”) (DR ROI > DR N ).
  • the radiation dose adjusting unit 120 starts exposure with the radiation dose X ROI , and the process proceeds to step 328.
  • the radiation dose X ROI remains unchanged.
  • step 328 ROI setting processing is started in the ROI setting unit 138, and the process proceeds to step 330.
  • step 330 the moving image editing process is executed by the moving image editing unit 130, and then the image display process is executed in step 332, and the process proceeds to step 334.
  • step 334 it is determined whether or not the ROI setting unit 138 can set the region of interest from the moving image. If the determination is negative, the process returns to step 330 to continue moving image editing and image display. If the determination in step 334 is affirmative, it is determined that the ROI setting has been completed, the process proceeds to step 336 to end the exposure, and then the process proceeds to step 338 to cancel the prohibition of ABC control. This routine ends.
  • the histogram when converting the photoelectric conversion signal under radiation dose X N in the steady state to the tone signal the dynamic range compression ratio DR N regions of the steady state It is distributed over almost the whole area.
  • the dynamic range compression ratio DR N in the steady state it is predicted based on the radiation dose X N in the steady state.
  • FIGS. 10B and 11A are the same characteristic diagram).
  • step 324 in FIG. 9 the dynamic range compression ratio is increased (DR ROI ).
  • the dynamic range of the region suitable for the histogram distribution biased toward the lower QL value can be obtained.
  • the radiation dose exposed from the radiation exposure source 22A is suppressed as much as possible (lower than the normal time), and the QL based on the lowered radiation dose is set.
  • the dynamic range compression rate was set higher than in the steady state to match the distribution of the value gramogram. For this reason, even if the distribution of the QL value is biased, the dynamic range can be used without waste, and both reduction of the exposure dose of the subject due to the radiation dose reduction and high-precision ROI setting can be achieved.
  • the radiation energy of radiation is lower than the steady state, but the radiation energy is not lowered.
  • the so-called duty of radiation exposure may be reduced.
  • the radiation dose (cumulative value) to be exposed per unit time can be suppressed.
  • the frame rate in the radiation detector 26 in the electronic cassette 20 may be lowered by the amount of the reduced duty.
  • the radiation filter is temporarily (within the region of interest setting) between the subject and the subject without changing the radiation dose from the radiation exposure source 22A. May be interposed.
  • the radiation filter includes, for example, a so-called diaphragm mechanism that can be installed on the radiation surface of the radiation radiation source 22A.
  • a so-called diaphragm mechanism that can be installed on the radiation surface of the radiation radiation source 22A.
  • attaching an ND (darkening) filter to the range and adjusting the aperture are the same in terms of the role of adjusting (reducing) exposure.
  • ND darkening
  • the diaphragm mechanism is a substitute for a case where the radiation filter cannot be practically used depending on the type of radiation. Applicable.
  • the radiation detector 26 in the electronic cassette 20 is a so-called area sensor in which detection pixels are two-dimensionally arranged, but only for a moving image that does not require a higher frame rate than a still image, Newly equipped with a line sensor in which pixels in the main scanning direction are arranged and a scanning mechanism unit that moves the line sensor in the sub-scanning direction, and a function of acquiring a two-dimensional image in time series by scanning of the scanning mechanism unit An electronic cassette may be manufactured. Further, a line sensor and a scanning mechanism unit may be built in the standing table 42 or the standing table 36 shown in FIG.
  • a line sensor for example, after a region of interest (ROI) is set, if a moving image is specified in the ROI region, at least the sub-scanning range can be reduced. Can be reduced.
  • ROI region of interest
  • the radiation energy of the radiation from the radiation exposure source 22A is set to a constant radiation energy that is lower than the steady state. It may be changed (eg increased).
  • the compression ratio of the dynamic range may be gradually changed.
  • the change may be continuous or stepwise, and may be changed only when an instruction is given. Moreover, although the change of the radiant energy is correlated with the change of the compression ratio of the dynamic range, independent control may be performed.
  • the present invention is not limited to this.
  • other radiation such as ⁇ -rays and ⁇ -rays included.

Abstract

The purpose of the present invention is to reduce the exposure amount of radiation to a subject without adversely affecting the identification of a region-of-interest mainly in the shooting of a moving image. In a radiographic image shooting system, when a moving image is to be shot, the exposure of radiation to a subject is continued for a longer period compared with that in the shooting of a still image, and therefore it is needed to have the exposure amount of radiation to a subject under consideration. Then, during the setting of a region-of-interest (ROI) which is to be performed before image shooting, the amount of radiation from a radiation source (22A) is reduced as possible (at a level lower than a level in a stationary time), and the compression rate of a dynamic range is increased compared with that in a stationary time in accordance with the distribution of a histogram of an QL value on the basis of the reduced amount of radiation. Consequently, even when the distribution of the QL value is unbalanced, it becomes possible to utilize the dynamic range with economy and it also becomes possible to achieve both the reduction in exposure amount of radiation to a subject through the reduction in the amount of radiation and the highly accurate setting of an ROI.

Description

放射線動画像撮影装置、放射線動画像撮影装置用関心領域設定方法、放射線画像撮影システム、放射線動画像撮影制御プログラム、及び放射線動画像撮影制御プログラム記憶媒体Radiation moving image capturing apparatus, region of interest setting method for radiation moving image capturing apparatus, radiation image capturing system, radiation moving image capturing control program, and radiation moving image capturing control program storage medium
 本願は2011年9月21日出願の日本出願第2011-206469号の優先権を主張すると共に、その全文を参照により本明細書に援用する。
 本発明は、被検体に向けて放射線を曝射し、被検体を通過した放射線量を放射線検出器で受けて得た静止画像を連続的に撮影することで被検体の動画像を生成する射線動画像撮影装置、放射線動画像撮影装置用関心領域設定方法、放射線画像撮影システム、放射線動画像撮影制御プログラム、及び放射線動画像撮影制御プログラム記憶媒体に関するものである。
This application claims the priority of Japanese application No. 2011-206469 filed on Sep. 21, 2011, the entire text of which is incorporated herein by reference.
The present invention is directed to generating a moving image of a subject by continuously capturing still images obtained by exposing a subject to radiation and receiving a radiation amount passing through the subject with a radiation detector. The present invention relates to a moving image capturing apparatus, a region of interest setting method for a radiation moving image capturing apparatus, a radiation image capturing system, a radiation moving image capturing control program, and a radiation moving image capturing control program storage medium.
 近年、TFT(Thin Film Transistor)アクティブマトリクス基板上に放射線感応層を配置し、放射線量をデジタルデータ(電気信号)に変換できるFPD(Flat Panel Detector)等の放射線検出器(「電子カセッテ」等という場合がある)が実用化されており、この放射線検出器を用いて、曝射された放射線量により表わされる放射線画像を撮影する放射線画像撮影装置が実用化されている。 In recent years, radiation detectors such as FPD (Flat Panel Detector) that can arrange radiation sensitive layers on TFT (Thin Film Transistor) active matrix substrates and convert radiation dose into digital data (electrical signals) (referred to as “electronic cassette” etc.) In some cases, a radiation image capturing apparatus that captures a radiation image represented by the amount of radiation that has been exposed using this radiation detector has been put into practical use.
 なお、放射線量は、例えば、互換をもって発光量に変換され、その後、電気信号に変換される間接変換方式と、放射線量から直接電気信号に変換される直接変換方式とがあり、適宜選択して採用される。 The radiation dose is, for example, interchangeably converted into a light emission amount and then converted into an electric signal, and then a direct conversion method in which the radiation dose is directly converted into an electric signal, and is selected as appropriate. Adopted.
 ところで、上記のような放射線画像撮影装置では、一定時間毎に放射線検出器で検出した画像情報を連続して再生することで、所謂動画像を表示することが考えられている。なお、一定時間の間隔は、短ければ短いほど連続性が向上して、動画像としての画質がよいが、その分画像情報量が増えることになるのは、一般のCCDやCMOS等を用いた撮像装置(イメージセンサ)と同様である。放射線画像撮影装置においては、撮影する画像コマ数が増えれば、被検者への放射線量が増えることになるため、適切な画像コマ数を選択することが好ましい。なお、「適切な画像コマ数」とは、撮影対象(被検者における関心領域(ROI)内の画像)の動きが速いか遅いか、当該動きの変化量を重視するか否か等、撮影目的に合わせて決めた画像コマ数である。 By the way, in the radiographic imaging apparatus as described above, it is considered to display a so-called moving image by continuously reproducing image information detected by a radiation detector at regular intervals. Note that the shorter the time interval, the better the continuity and the better the image quality as a moving image. However, the amount of image information is increased by using a general CCD or CMOS. It is the same as an imaging device (image sensor). In the radiographic image capturing apparatus, if the number of image frames to be captured increases, the radiation dose to the subject increases. Therefore, it is preferable to select an appropriate number of image frames. The “appropriate number of image frames” refers to whether the movement of the imaging target (image in the region of interest (ROI) in the subject) is fast or slow, whether or not the change amount of the movement is important, etc. This is the number of image frames decided according to the purpose.
 一方、放射線画像撮影装置では、動画像を撮影する場合、撮影した画像情報に基づき、放射線量を制御して、放射線検出器による検出状態を最適に維持するフィードバック制御(ABC「Auto Brightness Control」制御)が必須である。 On the other hand, in the radiographic imaging device, when capturing a moving image, feedback control (ABC “Auto Brightness Control” control is performed to control the radiation dose based on the captured image information and optimally maintain the detection state by the radiation detector. ) Is essential.
 特開2010-273834号公報には、造影血管の透視画像及びDA(Digital Angiography)画像を表示するX線画像診断装置が開示されている。 Japanese Patent Application Laid-Open No. 2010-273434 discloses an X-ray diagnostic imaging apparatus that displays a fluoroscopic image of a contrasted blood vessel and a DA (Digital Angiography) image.
 また、特開平9-266901号公報には、放射線画像の画像処理条件設定装置が開示されている。 Also, Japanese Patent Laid-Open No. 9-266901 discloses an image processing condition setting device for radiographic images.
 特開2010-273834号公報には、関心領域内の画像レベルに基づいてABC制御を行うX線画像診断装置において、ユーザ操作に応じて、ABC制御を適宜解除して、そのときのX線条件を固定することができる技術が開示されている。 Japanese Patent Application Laid-Open No. 2010-27383 discloses an X-ray diagnostic imaging apparatus that performs ABC control based on an image level in a region of interest by appropriately canceling ABC control according to a user operation, and the X-ray condition at that time A technique that can fix the above is disclosed.
 ここで、放射線画像撮影装置による動画像撮影では、当然静止画撮影に比べて被検者(検査を受ける者)への被曝量が多くなる傾向にある。このため、当該被曝量を軽減することが重要な課題である。 Here, naturally, moving image shooting by a radiographic imaging device tends to increase the amount of exposure to a subject (a person undergoing an examination) compared to still image shooting. For this reason, reducing the exposure dose is an important issue.
 被曝量を軽減するためには、放射線発生装置からの放射される放射線量を減らせばよいが、現状では、前記関心領域が確定する以前から、前記ABC制御が実行されており、このABC制御に起因して、所謂本撮影前の画像であるにも関わらず、放射線量が増大する方向に制御される場合がある。 In order to reduce the exposure dose, the radiation dose emitted from the radiation generating device may be reduced. However, at present, the ABC control is executed before the region of interest is determined. As a result, the radiation dose may be controlled to increase in spite of the so-called pre-photographing image.
 これを解消するために、ABC制御を解除すると共に、放射線発生装置からの放射線量を低線量とすれば、無用な放射線量が出力されずに、関心領域を特定することが可能となる。 In order to solve this problem, if the ABC control is canceled and the radiation dose from the radiation generator is set to a low dose, it becomes possible to specify the region of interest without outputting unnecessary radiation dose.
 なお、特開2010-273834号公報に記載された技術は、ABC制御を解除することが記載されているが、当該ABC制御を解除するタイミングとしては、直接X線を検出する部位を撮影する場合などとしており、作用効果が異なる。また、特開2010-273834号公報は、ユーザ操作に応じてABC制御を解除するものであり、ABC制御と関心領域との因果関係はない。 Note that the technique described in Japanese Patent Application Laid-Open No. 2010-273834 describes releasing the ABC control. However, the timing for releasing the ABC control is when imaging a region that directly detects X-rays. The effects are different. Japanese Patent Application Laid-Open No. 2010-273434 releases ABC control in response to a user operation, and there is no causal relationship between ABC control and a region of interest.
 しかしながら、ABC制御の解除、並びに低放射線量の下では、放射線検出器で検出する光量自体が少なくなるため、通常のダイナミックレンジでの検出では、所謂露出不足と同等の現象となり、関心領域の特定要素(特定までの所要時間、特定された領域の信頼性等)に影響を及ぼすことになる。 However, under the cancellation of ABC control and a low radiation dose, the amount of light detected by the radiation detector itself is small. Therefore, detection in the normal dynamic range is a phenomenon equivalent to so-called underexposure, and the region of interest is specified. Factors (time required until identification, reliability of the identified area, etc.) will be affected.
 ここで、放射線撮像分野において、関心領域を明瞭に認識可能とする目的でダイナミックレンジの圧縮を行うものとしては、例えば特開平9-266901号公報のように、関心領域である脊椎全体を表現するのに適したダイナミックレンジ圧縮を行うものなどがある。ただし、ABC制御とダイナミックレンジの圧縮との因果関係はない。 Here, in the field of radiation imaging, as a method of performing dynamic range compression for the purpose of clearly recognizing a region of interest, the entire spine that is a region of interest is expressed as in, for example, Japanese Patent Laid-Open No. 9-266901. There is one that performs dynamic range compression suitable for the above. However, there is no causal relationship between ABC control and dynamic range compression.
 本発明は上記事実を考慮し、主として動画像撮影する場合に、関心領域の特定に悪影響を及ぼすことなく、被検体への放射線被曝量を低減することができる放射線動画像撮影装置、放射線動画像撮影装置用関心領域設定方法、放射線画像撮影システム、放射線動画像撮影制御プログラム、及び放射線動画像撮影制御プログラム記憶媒体を提供する。 In consideration of the above-described facts, the present invention provides a radiological moving image capturing apparatus and a radiological moving image capable of reducing the radiation exposure dose to a subject without adversely affecting the identification of a region of interest when mainly capturing a moving image. An imaging device region-of-interest setting method, a radiographic imaging system, a radiographic video imaging control program, and a radiographic video imaging control program storage medium are provided.
 本発明の第1の態様は、放射線動画像撮影装置であって、設定された定常範囲の放射線エネルギーの放射線を、被検体に向けて曝射する放射線曝射部から曝射され、かつ前記被検体を通過した放射線量を、複数の画素を備えた放射線検出器で受け、当該画素毎に受ける放射線量に応じた階調信号を出力する放射線画像撮影部と、前記放射線画像撮影部から階調信号を取得して、所定のダイナミックレンジの下で当該階調信号を読み取り、1フレーム毎の静止画像情報を生成すると共に、前記静止画像を連続的に撮影することで前記被検体の動画像を生成する動画像情報生成部と、所定の制御周期で、前記放射線曝射部から曝射する前記放射線の放射線エネルギーの設定値をフィードバック制御する制御部と、前記制御部によるフィードバック制御を禁止すると共に、前記被検体の被曝量を前記定常範囲での放射線エネルギーによる被曝量よりも抑制した状態で実行され、前記動画像情報生成部で生成された画像の一部を関心領域として設定する関心領域設定部と、を有している。 According to a first aspect of the present invention, there is provided a radiological moving image capturing apparatus, wherein a radiation having a set steady range of radiation energy is exposed from a radiation exposure unit that exposes radiation toward a subject, and the subject A radiation image capturing unit that receives a radiation dose that has passed through the specimen with a radiation detector having a plurality of pixels and outputs a gradation signal corresponding to the radiation dose received for each pixel, and a gradation from the radiation image capturing unit A signal is acquired, the gradation signal is read under a predetermined dynamic range, and still image information is generated for each frame, and the moving image of the subject is captured by continuously capturing the still image. A moving image information generation unit to be generated; a control unit that performs feedback control of a set value of radiation energy of the radiation that is emitted from the radiation exposure unit at a predetermined control cycle; and a feedback by the control unit. The control is prohibited, and the exposure amount of the subject is executed in a state where the exposure amount is suppressed from the exposure amount due to the radiation energy in the steady range, and a part of the image generated by the moving image information generation unit is set as a region of interest. A region of interest setting unit to be set.
 本態様によれば、通常の動画像撮影の手順としては、放射線曝射部により、設定された定常範囲の放射線エネルギーの放射線を、被検体に向けて曝射する。 According to this aspect, as a normal moving image capturing procedure, the radiation exposure unit exposes radiation of radiation energy in a set steady range toward the subject.
 放射線画像撮影部では、放射線曝射部から曝射され、かつ被検体を通過した放射線量を、複数の画素を備えた放射線検出器で受け、当該画素毎に受ける放射線量に応じた階調信号を出力する。 In the radiographic image capturing unit, the radiation amount exposed from the radiation exposure unit and passed through the subject is received by a radiation detector having a plurality of pixels, and a gradation signal corresponding to the radiation amount received for each pixel Is output.
 次に、動画像情報生成部では、放射線画像撮影部から階調信号を取得して、所定のダイナミックレンジの下で当該階調信号を読み取り、1フレーム毎の静止画像情報を生成すると共に、静止画像を連続的に撮影することで被検体の動画像を生成する。 Next, the moving image information generation unit acquires a gradation signal from the radiographic image capturing unit, reads the gradation signal under a predetermined dynamic range, generates still image information for each frame, and A moving image of the subject is generated by continuously capturing images.
 この場合、制御部では、所定の制御周期で、前記放射線曝射部から曝射する前記放射線の放射線エネルギーの設定値をフィードバック制御する。 In this case, the control unit feedback-controls the set value of the radiation energy of the radiation exposed from the radiation exposure unit at a predetermined control cycle.
 ここで、撮影指示直後は、関心領域設定部において、撮影される動画像の中から関心領域を設定する。 Here, immediately after the photographing instruction, the region of interest setting unit sets the region of interest from the moving images to be photographed.
 このとき、関心領域設定部では、制御部によるフィードバック制御を禁止すると共に、被検体の被曝量を定常範囲よりも抑制した状態で、画像の一部を関心領域として設定する。 At this time, the region-of-interest setting unit prohibits feedback control by the control unit and sets a part of the image as the region of interest in a state where the exposure amount of the subject is suppressed from the steady range.
 このように、所謂本撮影ではない関心領域設定期間は、被検体の被曝量を定常範囲よりも抑制することができる。また、フィードバック制御を禁止することで、抑制した状態を維持することができる。 Thus, during the region-of-interest setting period that is not so-called main imaging, the exposure dose of the subject can be suppressed from the steady range. Moreover, the state which was suppressed can be maintained by prohibiting feedback control.
 第1の態様において、前記被曝量の抑制は、前記放射線曝射部に対して指示する放射線エネルギーを定常範囲よりも低くすることであってよい。 1st aspect WHEREIN: The suppression of the said exposure amount may be making the radiation energy instruct | indicated with respect to the said radiation exposure part lower than a steady range.
 放射線の発生源自体の放射線エネルギーを定常範囲よりも低くすることで、被検体への被曝量を低減することができる。 The exposure dose to the subject can be reduced by making the radiation energy of the radiation source itself lower than the steady range.
 第1の態様において、前記被曝量の抑制は、定常時よりも低いフレームレートとすることであってよい。 In the first aspect, the suppression of the exposure dose may be a frame rate lower than that in a steady state.
 放射線検出器におけるフレームレートを定常時よりも低くすることで、その分、必要な放射線量が減らしても、確実に動画像の基となる静止画像を生成することができる。なお、この場合、放射線曝射部から曝射される放射線をフレームレートに同期させて、間欠に出力することで、各画素毎に検出する放射線量自体を維持することができ、適正な階調信号を得ることができる。 By making the frame rate in the radiation detector lower than that in the steady state, it is possible to reliably generate a still image that is the basis of a moving image even if the necessary radiation dose is reduced accordingly. In this case, the radiation dose itself detected by each pixel can be maintained by synchronizing the radiation emitted from the radiation exposure unit with the frame rate and outputting it intermittently. A signal can be obtained.
 第1の態様において、前記前記被曝量の抑制は、前記放射線曝射部と前記被検体との間に、放射線をカットするフィルタを配置することであってよい。 In the first aspect, the exposure dose may be suppressed by disposing a filter for cutting radiation between the radiation exposure unit and the subject.
 例えば、放射線曝射部と前記被検体との間に、放射線をカットするフィルタを介在させ、物理的に放射線の一部を遮蔽してもよい。なお、フィルタは、放射線曝射部の曝射面等に設置可能な所謂絞り機構を含むものとする。 For example, a part of the radiation may be physically shielded by interposing a filter for cutting the radiation between the radiation exposure unit and the subject. The filter includes a so-called diaphragm mechanism that can be installed on an exposure surface of the radiation exposure unit.
 第1の態様において、前記被曝量が抑制され、かつ前記フィードバック制御が禁止されている間は、前記ダイナミックレンジの圧縮のパラメータである前記階調信号に対する前記画像情報の変化率を、フィードバック制御中よりも大きくしてもよい。 In the first aspect, while the exposure dose is suppressed and the feedback control is prohibited, the rate of change of the image information with respect to the gradation signal, which is a parameter for compression of the dynamic range, is being feedback controlled. May be larger.
 被検体の被曝量を定常範囲よりも抑制するために、フィードバック制御が禁止されていると、当然放射線エネルギーを高くする制御が行えない。このような状況では、例えば、前記放射線曝射部に対して指示する放射線エネルギーを定常範囲よりも低くしていると、画素毎に検出する放射線量自体が少なくなり、階調信号を適正に得ることができない場合がある。 If the feedback control is prohibited in order to suppress the exposure dose of the subject from the steady range, naturally the control to increase the radiation energy cannot be performed. In such a situation, for example, if the radiation energy instructed to the radiation exposure unit is lower than the steady range, the amount of radiation detected for each pixel is reduced, and a gradation signal is appropriately obtained. It may not be possible.
 そこで、ダイナミックレンジの圧縮のパラメータを、フィードバック制御中のダイナミックレンジの圧縮のパラメータよりも大きくする。 Therefore, the dynamic range compression parameter is made larger than the dynamic range compression parameter during feedback control.
 ダイナミックレンジの圧縮のパラメータとは、階調信号に対する画像情報の変化率であり、放射線エネルギーが低い分、放射線検出器で受ける放射線量が少なく、階調信号は低レベル側に偏る傾向となり、階調変化(濃度変化)が低い。この偏った領域に合わせて、ダイナミックレンジの圧縮のパラメータ、すなわち階調信号に対する画像情報の変化率を大きくすることで、所謂アンダー気味の画像から適正な画像情報を得ることができる。 The dynamic range compression parameter is the rate of change of the image information with respect to the gradation signal. The radiation dose received by the radiation detector is small because the radiation energy is low, and the gradation signal tends to be biased toward the low level. Tonal change (density change) is low. Appropriate image information can be obtained from a so-called underimage by increasing the dynamic range compression parameter, that is, the rate of change of the image information with respect to the gradation signal, in accordance with this biased region.
 第1の態様において、前記関心領域設定部により関心領域が設定された後は、前記制御部によるフィードバック制御の対象を、当該関心領域内の画像としてもよい。 In the first aspect, after the region of interest is set by the region of interest setting unit, the target of feedback control by the control unit may be an image in the region of interest.
 例えば、関心領域内外で区別して放射線量を調整することができれば、関心領域内は適正な放射線エネルギーとなるようにフィードバック補正し、関心領域外は放射線量を低くすることで、被検体へ曝射される放射線量を低減することができる。 For example, if the radiation dose can be adjusted separately inside and outside the region of interest, feedback correction is performed so that appropriate radiation energy is obtained within the region of interest, and the radiation dose is reduced outside the region of interest, thereby exposing the subject. The amount of radiation emitted can be reduced.
 関心領域内外で区別して放射線量を調整する部としては、例えば、放射線曝射部の曝射面を区画して独立して制御する、或いは、前記放射線曝射部と前記被検体との間に、アパーチャーを配置する等の部が考えられ、動画像の場合、関心領域の移動に追従させればよい。 As a unit for adjusting the radiation dose by distinguishing between the inside and outside of the region of interest, for example, the exposure surface of the radiation exposure unit is partitioned and controlled independently, or between the radiation exposure unit and the subject For example, a moving image may be made to follow the movement of the region of interest.
 本発明の第2の態様は、関心領域設定方法であり、被検体に向けて、定常範囲での放射線エネルギーによる被曝量よりも抑制した放射線エネルギーで放射線を曝射し、被検体を通過した放射線量を、複数の画素を備えた放射線検出器で受け、当該画素毎に受ける放射線量に応じた階調信号に基づいて、1フレーム毎の静止画像情報を生成すると共に、前記静止画像を連続的に撮影することで前記被検体の動画像を生成し、生成された画像の一部を関心領域として設定し、当該関心領域を設定した後、前記放射線エネルギーの抑制を解除して、所定の制御周期で、曝射する前記放射線の放射線エネルギーの設定値をフィードバック制御する処理を開始する。 The second aspect of the present invention is a region-of-interest setting method, in which radiation is irradiated toward a subject with radiation energy that is less than the exposure amount due to radiation energy in a steady range and passes through the subject. The amount is received by a radiation detector having a plurality of pixels, and still image information for each frame is generated based on a gradation signal corresponding to the amount of radiation received for each pixel, and the still image is continuously displayed. To generate a moving image of the subject, set a part of the generated image as a region of interest, and after setting the region of interest, release the suppression of the radiation energy and perform predetermined control In a cycle, processing for feedback control of the set value of the radiation energy of the radiation to be exposed is started.
 第2の態様によれば、通常の動画像撮影の手順としては、設定された定常範囲の放射線エネルギーの放射線を、被検体に向けて曝射し、曝射され、かつ被検体を通過した放射線量を、複数の画素を備えた放射線検出器で受け、当該画素毎に受ける放射線量に応じた階調信号を所定のダイナミックレンジの下で読み取り、1フレーム毎の静止画像情報を生成すると共に、静止画像を連続的に撮影することで被検体の動画像を生成する。 According to the second aspect, as a normal moving image capturing procedure, radiation having radiation energy in a set steady range is exposed toward the subject, and is exposed and passed through the subject. The amount is received by a radiation detector having a plurality of pixels, a gradation signal corresponding to the amount of radiation received for each pixel is read under a predetermined dynamic range, and still image information for each frame is generated, A moving image of the subject is generated by continuously capturing still images.
 この場合、制御部では、所定の制御周期で、前記放射線曝射部から曝射する前記放射線の放射線エネルギーの設定値をフィードバック制御する。 In this case, the control unit feedback-controls the set value of the radiation energy of the radiation exposed from the radiation exposure unit at a predetermined control cycle.
 ここで、撮影指示直後は、撮影される動画像の中から関心領域を設定する。この関心領域設定中は、フィードバック制御を禁止すると共に、被検体の被曝量を定常範囲よりも抑制した状態で、画像の一部を関心領域として設定する。 Here, immediately after the shooting instruction, the region of interest is set from the moving images to be shot. During the region-of-interest setting, feedback control is prohibited and a part of the image is set as the region of interest while the exposure dose of the subject is suppressed from the steady range.
 このように、所謂本撮影ではない関心領域設定期間は、被検体の被曝量を定常範囲よりも抑制することができる。また、フィードバック制御を禁止することで、抑制した状態を維持することができる。 Thus, during the region-of-interest setting period that is not so-called main imaging, the exposure dose of the subject can be suppressed from the steady range. Moreover, the state which was suppressed can be maintained by prohibiting feedback control.
 第2の態様において、前記被曝量の抑制は、前記放射線曝射部に対して指示する放射線エネルギーを定常範囲よりも低くすることであってよい。 2nd aspect WHEREIN: The suppression of the said exposure amount may be making the radiation energy instruct | indicated with respect to the said radiation exposure part lower than a steady range.
 放射線の発生源自体の放射線エネルギーを定常範囲よりも低くすることで、被検体への被曝量を低減することができる。 The exposure dose to the subject can be reduced by making the radiation energy of the radiation source itself lower than the steady range.
 第2の態様において、前記被曝量の抑制が、定常時よりも低いフレームレートとすることであってよい。 In the second aspect, the suppression of the exposure dose may be a frame rate lower than that in a steady state.
 放射線検出器におけるフレームレートを定常時よりも低くすることで、その分、必要な放射線量が減らしても、確実に動画像の基となる静止画像を生成することができる。なお、この場合、放射線曝射部から曝射される放射線をフレームレートに同期させて、間欠に出力することで、各画素毎に検出する放射線量自体を維持することができ、適正な階調信号を得ることができる。 By making the frame rate in the radiation detector lower than that in the steady state, it is possible to reliably generate a still image that is the basis of a moving image even if the necessary radiation dose is reduced accordingly. In this case, the radiation dose itself detected by each pixel can be maintained by synchronizing the radiation emitted from the radiation exposure unit with the frame rate and outputting it intermittently. A signal can be obtained.
 第2の態様において、前記フィードバック制御が禁止されている間は、前記階調信号を読み取るダイナミックレンジの圧縮のパラメータを、フィードバック制御中のダイナミックレンジの圧縮のパラメータとしてもよい。 In the second aspect, while the feedback control is prohibited, the dynamic range compression parameter for reading the gradation signal may be used as the dynamic range compression parameter during the feedback control.
 被検体の被曝量を定常範囲よりも抑制するために、フィードバック制御が禁止されていると、当然放射線エネルギーを高くする制御が行えない。このような状況では、例えば、前記放射線曝射部に対して指示する放射線エネルギーを定常範囲よりも低くしていると、画素毎に検出する放射線量自体が少なくなり、階調信号を適正に得ることができない場合がある。 If the feedback control is prohibited in order to suppress the exposure dose of the subject from the steady range, naturally the control to increase the radiation energy cannot be performed. In such a situation, for example, if the radiation energy instructed to the radiation exposure unit is lower than the steady range, the amount of radiation detected for each pixel is reduced, and a gradation signal is appropriately obtained. It may not be possible.
 そこで、ダイナミックレンジの圧縮のパラメータを、フィードバック制御中のダイナミックレンジの圧縮のパラメータよりも大きくする。 Therefore, the dynamic range compression parameter is made larger than the dynamic range compression parameter during feedback control.
 ダイナミックレンジの圧縮のパラメータとは、階調信号に対する画像情報の変化率であり、放射線エネルギーが低い分、放射線検出器で受ける放射線量が少なく、階調信号は低レベル側に偏る傾向となり、階調変化(濃度変化)が低い。この偏った領域に合わせて、ダイナミックレンジの圧縮のパラメータ、すなわち階調信号に対する画像情報の変化率を大きくすることで、所謂アンダー気味の画像から適正な画像情報を得ることができる。 The dynamic range compression parameter is the rate of change of the image information with respect to the gradation signal. The radiation dose received by the radiation detector is small because the radiation energy is low, and the gradation signal tends to be biased toward the low level. Tonal change (density change) is low. Appropriate image information can be obtained from a so-called underimage by increasing the dynamic range compression parameter, that is, the rate of change of the image information with respect to the gradation signal, in accordance with this biased region.
 本発明の第3の態様は、放射線画像撮影システムであり、第1の態様の放射線動画像撮影装置と、診断情報や施設予約の入力、閲覧、並びに放射線動画像の撮影依頼や撮影予約を行う端末装置と、前記端末装置からの撮影依頼を受け付け、前記放射線動画像撮影装置における放射線画像の撮影スケジュールを管理すると共に、撮影された放射線動画像を一括管理するサーバーと、を有している。 A third aspect of the present invention is a radiographic imaging system, and performs input and browsing of diagnostic information and facility reservation, and radiographic video imaging request and imaging reservation with the radiographic video imaging apparatus of the first aspect. A terminal device; and a server that accepts an imaging request from the terminal device, manages a radiographic imaging schedule in the radiographic video imaging device, and collectively manages radiographic images taken.
 第3の態様によれば、特に病院内における、放射線科部門内において、診療予約、診断記録等の情報管理を行うためのシステムとして適用可能であり、病院情報システムの一部となり得る。 According to the third aspect, it can be applied as a system for managing information such as medical appointment reservations and diagnostic records, particularly in a radiology department in a hospital, and can be a part of a hospital information system.
 例えば、被検体の情報を一括管理することで、当該被検体が被曝する放射線量を管理することで、被検体毎に、関心領域の設定時の放射線エネルギーの抑制率を決定する等の調整が可能である。 For example, by managing the information of the subject collectively, by managing the radiation dose to which the subject is exposed, adjustments such as determining the suppression rate of the radiation energy at the time of setting the region of interest can be performed for each subject. Is possible.
 本発明の第4の態様は、コンピュータを、第1の態様の放射線動画像撮影装置の動画像情報生成部、制御部並びに関心領域設定部として機能させる放射線動画像撮影制御プログラムである。なお、放射線動画像撮影制御プログラムは、記憶媒体に記憶させることができる。
 即ち、本発明の第5の態様は、コンピュータに放射線動画像撮影処理を実行させるプログラムを記憶した持続性コンピュータ可読記憶媒体であって、前記放射線動画像撮影処理が、被検体に向けて、定常範囲での放射線エネルギーによる被曝量よりも抑制した放射線エネルギーで放射線を曝射し、被検体を通過した放射線量を、複数の画素を備えた放射線検出器で受けることで取得された、当該画素毎に受ける放射線量に応じた階調信号に基づいて、1フレーム毎の静止画像情報を生成し、前記静止画像を連続的に撮影することで前記被検体の動画像を生成し、生成された画像の一部を関心領域として設定し、当該関心領域を設定した後、前記放射線エネルギーの抑制を解除して、所定の制御周期で、曝射する前記放射線の放射線エネルギーの設定値をフィードバック制御する処理を開始することを含む。
According to a fourth aspect of the present invention, there is provided a radiation moving image photographing control program that causes a computer to function as a moving image information generation unit, a control unit, and a region of interest setting unit of the radiation moving image photographing apparatus according to the first aspect. The radiological moving image capturing control program can be stored in a storage medium.
That is, the fifth aspect of the present invention is a persistent computer-readable storage medium storing a program for causing a computer to execute a radiation moving image capturing process, wherein the radiation moving image capturing process is directed toward a subject. For each pixel obtained by exposing the radiation with a radiation energy that is less than the exposure amount due to the radiation energy in the range, and receiving the radiation amount that has passed through the subject with a radiation detector having a plurality of pixels. A still image information for each frame is generated based on a gradation signal corresponding to the amount of radiation received by the camera, and a moving image of the subject is generated by continuously capturing the still images, and the generated image Is set as a region of interest, and after setting the region of interest, the radiation energy is released at a predetermined control period after the suppression of the radiation energy is released. It includes initiating a process of feedback control of the set value.
 以上説明した如く本発明の各態様では、主として動画像撮影する場合に、関心領域の特定に悪影響を及ぼすことなく、被検体への放射線被曝量を低減することができるという優れた効果を有する。 As described above, each aspect of the present invention has an excellent effect that the radiation exposure dose to the subject can be reduced without adversely affecting the identification of the region of interest when mainly capturing moving images.
本実施の形態に係る放射線情報システムの構成を示すブロック図である。It is a block diagram which shows the structure of the radiation information system which concerns on this Embodiment. 本実施の形態に係る放射線画像撮影システムの放射線撮影室における各装置の配置状態の一例を示す側面図である。It is a side view which shows an example of the arrangement | positioning state of each apparatus in the radiography room of the radiographic imaging system which concerns on this Embodiment. 本実施の形態に係る放射線検出器(一部)の概略構成を示す断面模式図である。It is a cross-sectional schematic diagram which shows schematic structure of the radiation detector (part) based on this Embodiment. 図2に示す放射線画像撮影システムの制御ブロック図である。It is a control block diagram of the radiographic imaging system shown in FIG. 本実施の形態に係る放射線画像撮影システムの撮影制御、並びにROI設定のための制御の流れを機能別に示したブロック図である。It is the block diagram which showed the imaging | photography control of the radiographic imaging system concerning this Embodiment, and the flow of control for ROI setting according to the function. 本実施の形態に係る放射線画像撮影準備制御ルーチンを示すフローチャートである。It is a flowchart which shows the radiographic imaging preparation control routine which concerns on this Embodiment. 本実施の形態に係る放射線画像撮影制御ルーチンを示すフローチャートである。It is a flowchart which shows the radiographic imaging control routine which concerns on this Embodiment. 本実施の形態に係るABC制御の流れを示すフローチャートである。It is a flowchart which shows the flow of ABC control which concerns on this Embodiment. 本実施の形態に係り、図7のステップ252における関心領域設定制御の詳細を示すフローチャートである。It is a flowchart which shows the detail of the region-of-interest setting control in step 252 of FIG. 7 according to the present embodiment. (A)は定常時に電子カセッテで検出する光電変換信号から生成されたQL値のヒストグラム、(B)はROI設定時に定常時よりも放射線量を低くした場合での電変換信号から生成されたQL値のヒストグラムである。(A) is a histogram of the QL value generated from the photoelectric conversion signal detected by the electronic cassette at the normal time, and (B) is the QL generated from the electric conversion signal when the radiation dose is lower than at the normal time at the ROI setting. It is a histogram of values. (A)はROI設定時に定常時よりも放射線量を低くした場合での電変換信号から生成されたQL値のヒストグラム(図10(B)と同一)、(B)は図11(A)におけるダイナミックレンジを圧縮した場合のであるQL値のヒストグラムである。(A) is a histogram of the QL value generated from the electric conversion signal when the radiation dose is lower than that at the time of steady setting when ROI is set (same as FIG. 10 (B)), and (B) is in FIG. 11 (A). It is a histogram of the QL value when the dynamic range is compressed.
 図1は、本実施の形態に係る放射線情報システム(以下、「RIS」(Radiology Information System)という。)10の概略構成図である。このRIS10は、静止画に加え、動画像を撮影することが可能である。なお、動画像の定義は、静止画を高速に次々と表示して、動画像として認知させることを言い、静止画を撮影し、電気信号に変換し、伝送して当該電気信号から静止画を再生する、というプロセスの高速に繰り返すものである。従って、前記「高速」の度合いによって、予め定められた時間内に同一領域(一部又は全部)を複数回撮影し、かつ連続的に再生する、所謂「コマ送り」も動画像に包含されるものとする。 FIG. 1 is a schematic configuration diagram of a radiation information system 10 (hereinafter referred to as “RIS” (Radiology Information System)) according to the present embodiment. The RIS 10 can capture a moving image in addition to a still image. The definition of a moving image means that still images are displayed one after another at a high speed and recognized as a moving image.The still image is photographed, converted into an electric signal, transmitted, and the still image is converted from the electric signal. The process of replaying is repeated at high speed. Accordingly, the so-called “frame advance” in which the same area (part or all) is photographed a plurality of times within a predetermined time and continuously reproduced in accordance with the degree of the “high speed” is also included in the moving image. Shall.
 RIS10は、放射線科部門内における、診療予約、診断記録等の情報管理を行うためのシステムであり、病院情報システム(以下、「HIS」(Hospital Information System)という。)の一部を構成する。 The RIS 10 is a system for managing information such as medical appointment reservations and diagnosis records in the radiology department, and constitutes a part of a hospital information system (hereinafter referred to as “HIS” (Hospital Information System)).
 RIS10は、複数台の撮影依頼端末装置(以下、「端末装置」という。)12、RISサーバー14、および病院内の放射線撮影室(あるいは手術室)の個々に設置された複数の放射線画像撮影システム(以下、「撮影システム」という。)16を有しており、これらが有線や無線のLAN(Local Area Network)等から成る病院内ネットワーク18に各々接続されて構成されている。なお、病院内ネットワーク18には、HIS全体を管理するHISサーバー(図示省略)が接続されている。また、前記放射線画像撮影システム16は、単一、或いは3以上の設備であってもよく、図1では、撮影室毎に設置しているが、単一の撮影室に2台以上の放射線画像撮影システム16を配置してもよい。 The RIS 10 includes a plurality of radiographic imaging systems installed individually in a plurality of imaging request terminal devices (hereinafter referred to as “terminal devices”) 12, a RIS server 14, and a radiographic room (or operating room) in a hospital. (Hereinafter referred to as “imaging system”) 16, which are connected to a hospital network 18 including a wired or wireless LAN (Local Area Network). The hospital network 18 is connected to an HIS server (not shown) that manages the entire HIS. The radiographic image capturing system 16 may be a single unit or three or more facilities. In FIG. 1, the radiographic image capturing system 16 is installed for each radiographing room. An imaging system 16 may be arranged.
 端末装置12は、医師や放射線技師が、診断情報や施設予約の入力、閲覧等を行うためのものであり、放射線画像の撮影依頼や撮影予約は、この端末装置12を介して行われる。各端末装置12は、表示装置を有するパーソナル・コンピュータを含んで構成され、RISサーバー14と病院内ネットワーク18を介して相互通信が可能とされている。 The terminal device 12 is used by doctors and radiographers to input and view diagnostic information and facility reservations, and radiographic image capturing requests and imaging reservations are performed via the terminal device 12. Each terminal device 12 includes a personal computer having a display device, and is capable of mutual communication via the RIS server 14 and the hospital network 18.
 一方、RISサーバー14は、各端末装置12からの撮影依頼を受け付け、撮影システム16における放射線画像の撮影スケジュールを管理するものであり、データベース14Aを含んで構成されている。 On the other hand, the RIS server 14 receives an imaging request from each terminal device 12 and manages a radiographic imaging schedule in the imaging system 16, and includes a database 14A.
 データベース14Aは、患者((被検体の属し、「被検者」という場合がある))の属性情報(氏名、性別、生年月日、年齢、血液型、体重、患者ID(Identification)等)、病歴、受診歴、過去に撮影した放射線画像等の患者に関する情報、撮影システム16で用いられる、後述する電子カセッテ20の識別番号(ID情報)、型式、サイズ、感度、使用開始年月日、使用回数等の電子カセッテ20に関する情報、および電子カセッテ20を用いて放射線画像を撮影する環境、すなわち、電子カセッテ20を使用する環境(一例として、放射線撮影室や手術室等)を示す環境情報を含む。 The database 14A includes attribute information (name, sex, date of birth, age, blood type, weight, patient ID (Identification), etc.) of a patient (which may be referred to as “subject's subject,“ subject ”)”, Patient history such as medical history, medical history, radiation images taken in the past, identification number (ID information) of electronic cassette 20 (model information) used in imaging system 16, model, size, sensitivity, use start date, use Information on the electronic cassette 20 such as the number of times, and environment information indicating an environment in which a radiographic image is captured using the electronic cassette 20, that is, an environment in which the electronic cassette 20 is used (for example, a radiography room or an operating room) are included. .
 なお、医療機関が管理する医療関連データをほぼ永久に保管し、必要なときに、必要な場所から瞬時に取り出すシステム(「医療クラウド」等と言う場合がある)を利用して、病院外のサーバーから、患者(被検者)の過去の個人情報等を入手してもよい。 In addition, medical-related data managed by medical institutions is stored almost permanently, and when necessary, a system (sometimes referred to as a “medical cloud”) that instantly retrieves data from the required location can be used outside the hospital. Past personal information of the patient (subject) may be obtained from the server.
 撮影システム16は、RISサーバー14からの指示に応じて医師や放射線技師の操作により放射線画像の撮影を行う。撮影システム16は、放射線曝射制御ユニット22(図4参照)の制御により放射線Xを曝射する放射線曝射源22Aから、曝射条件に従った線量とされた放射線Xを被検者に曝射する放射線発生装置24と、被検者の撮影対象部位を透過した放射線Xを吸収して電荷を発生し、発生した電荷量に基づいて放射線画像を示す画像情報を生成する放射線検出器26(図3参照)を内蔵する電子カセッテ20と、電子カセッテ20に内蔵されているバッテリを充電するクレードル28と、電子カセッテ20および放射線発生装置24を制御するコンソール30と、を備えている。 The imaging system 16 captures a radiographic image by an operation of a doctor or a radiographer according to an instruction from the RIS server 14. The imaging system 16 exposes the subject to the radiation X having a dose according to the exposure conditions from the radiation exposure source 22A that exposes the radiation X under the control of the radiation exposure control unit 22 (see FIG. 4). A radiation generating device 24 that emits radiation, and a radiation detector 26 that generates radiation by absorbing the radiation X transmitted through the imaging target region of the subject and generates image information indicating a radiation image based on the amount of the generated charge ( 3), a cradle 28 for charging a battery built in the electronic cassette 20, and a console 30 for controlling the electronic cassette 20 and the radiation generator 24.
 コンソール30は、RISサーバー14からデータベース14Aに含まれる各種情報を取得して後述するHDD88(図4参照)に記憶し、必要に応じて当該情報を用いて、電子カセッテ20および放射線発生装置24の制御を行う。 The console 30 acquires various types of information included in the database 14A from the RIS server 14 and stores them in an HDD 88 (see FIG. 4) described later. If necessary, the console 30 uses the information to store the electronic cassette 20 and the radiation generator 24. Take control.
 図2には、本実施の形態に係る撮影システム16の放射線撮影室32における各装置の配置状態の一例が示されている。 FIG. 2 shows an example of the arrangement state of each device in the radiation imaging room 32 of the imaging system 16 according to the present embodiment.
 図2に示される如く、放射線撮影室32には、立位での放射線撮影を行う際に用いられる立位台34と、臥位での放射線撮影を行う際に用いられる臥位台36とが設置されており、立位台34の前方空間は立位での放射線撮影を行う際の被検者38の撮影位置とされ、臥位台36の上方空間は臥位での放射線撮影を行う際の被検者40の撮影位置とされている。 As shown in FIG. 2, in the radiation imaging room 32, there are a standing table 34 used when performing radiography in a standing position and a prone table 36 used when performing radiation imaging in a lying position. The space in front of the standing table 34 is set as the imaging position of the subject 38 when performing radiography in the standing position, and the upper space of the prone table 36 is used in performing radiography in the prone position. This is the imaging position of the subject 40.
 立位台34には電子カセッテ20を保持する保持部42が設けられており、立位での放射線画像の撮影を行う際には、電子カセッテ20が保持部42に保持される。同様に、臥位台36には電子カセッテ20を保持する保持部44が設けられており、臥位での放射線画像の撮影を行う際には、電子カセッテ20が保持部44に保持される。 The standing table 34 is provided with a holding unit 42 that holds the electronic cassette 20, and the electronic cassette 20 is held by the holding unit 42 when a radiographic image is taken in the standing position. Similarly, a holding unit 44 that holds the electronic cassette 20 is provided in the lying position table 36, and the electronic cassette 20 is held by the holding unit 44 when a radiographic image is taken in the lying position.
 また、放射線撮影室32には、単一の放射線曝射源22Aからの放射線によって立位での放射線撮影も臥位での放射線撮影も可能とするために、放射線曝射源22Aを、水平な軸回り(図2の矢印A方向)に回動可能で、鉛直方向(図2の矢印B方向)に移動可能で、さらに水平方向(図2の矢印C方向)に移動可能に支持する支持移動機構46が設けられている。この図2の矢印A~C方向へ放射線曝射源22Aを移動(回動を含む)させる駆動源は、支持移動機構46に内蔵されており、ここでは、図示を省略する。 Further, in the radiation imaging room 32, the radiation exposure source 22A is installed in a horizontal position in order to enable radiography in the standing position and in the prone position by the radiation from the single radiation exposure source 22A. Support movement that can rotate around the axis (in the direction of arrow A in FIG. 2), move in the vertical direction (in the direction of arrow B in FIG. 2), and further move in the horizontal direction (in the direction of arrow C in FIG. 2). A mechanism 46 is provided. A drive source for moving (including turning) the radiation exposure source 22A in the directions of arrows A to C in FIG. 2 is built in the support moving mechanism 46, and is not shown here.
 一方、クレードル28には、電子カセッテ20を収納可能な収容部28Aが形成されている。 On the other hand, the cradle 28 is formed with an accommodating portion 28A capable of accommodating the electronic cassette 20.
 電子カセッテ20は、未使用時にはクレードル28の収容部28Aに収納された状態で内蔵されているバッテリに充電が行われ、放射線画像の撮影時には放射線技師等によってクレードル28から取り出され、撮影姿勢が立位であれば立位台34の保持部42に保持され、撮影姿勢が臥位であれば臥位台36の保持部44に保持される。 When the electronic cassette 20 is not used, the built-in battery is charged in a state of being accommodated in the accommodating portion 28A of the cradle 28. When a radiographic image is taken, the electronic cassette 20 is taken out of the cradle 28 by a radiographer or the like, and the photographing posture is established. If it is in the upright position, it is held in the holding part 42 of the standing table 34, and if it is in the upright position, it is held in the holding part 44 of the standing table 36.
 ここで、本実施の形態に係る撮影システム16では、図4に示される如く、放射線発生装置24とコンソール30との間、および電子カセッテ20とコンソール30との間で、無線通信によって各種情報の送受信を行う(詳細後述)。 Here, in the imaging system 16 according to the present embodiment, as shown in FIG. 4, various kinds of information are transmitted by wireless communication between the radiation generator 24 and the console 30 and between the electronic cassette 20 and the console 30. Send and receive (details will be described later).
 なお、電子カセッテ20は、立位台34の保持部42や臥位台36の保持部44で保持された状態のみで使用されるものではなく、その可搬性から、腕部,脚部等を撮影する際には、保持部に保持されていない状態で使用することもできる。 The electronic cassette 20 is not used only in the state of being held by the holding portion 42 of the standing base 34 or the holding portion 44 of the prone position base 36. When photographing, it can be used in a state where it is not held by the holding unit.
 図3は、電子カセッテ20に装備される放射線検出器26の3画素部分の構成を概略的に示す断面模式図である。 FIG. 3 is a schematic cross-sectional view schematically showing the configuration of the three pixel portions of the radiation detector 26 provided in the electronic cassette 20.
 図3に示される如く、放射線検出器26は、絶縁性の基板50上に、信号出力部52、センサ部54(TFT基板74)、およびシンチレータ56が順次積層しており、信号出力部52、センサ部54によりTFT基板74の画素群が設けられている。すなわち、複数の画素は、基板50上にマトリクス状に配列されており、各画素における信号出力部52とセンサ部54とが重なりを有する構成とされている。なお、信号出力部52とセンサ部54との間には、絶縁膜53が介在されている。 As shown in FIG. 3, the radiation detector 26 includes a signal output unit 52, a sensor unit 54 (TFT substrate 74), and a scintillator 56 that are sequentially stacked on an insulating substrate 50. A pixel group of the TFT substrate 74 is provided by the sensor unit 54. That is, the plurality of pixels are arranged in a matrix on the substrate 50, and the signal output unit 52 and the sensor unit 54 in each pixel are configured to overlap each other. An insulating film 53 is interposed between the signal output unit 52 and the sensor unit 54.
 シンチレータ56は、センサ部54上に透明絶縁膜58を介して形成されており、上方(基板50の反対側)または下方から入射してくる放射線を光に変換して発光する蛍光体を成膜したものである。このようなシンチレータ56を設けることで、被写体を透過した放射線を吸収して発光することになる。 The scintillator 56 is formed on the sensor unit 54 via a transparent insulating film 58, and forms a phosphor that emits light by converting radiation incident from above (opposite side of the substrate 50) or below into light. It is what. Providing such a scintillator 56 absorbs radiation transmitted through the subject and emits light.
 シンチレータ56が発する光の波長域は、可視光域(波長360nm~830nm)であることが好ましく、この放射線検出器26によってモノクロ撮像を可能とするためには、緑色の波長域を含んでいることがより好ましい。 The wavelength range of light emitted by the scintillator 56 is preferably in the visible light range (wavelength 360 nm to 830 nm), and in order to enable monochrome imaging by the radiation detector 26, the wavelength range of green is included. Is more preferable.
 シンチレータ56に用いる蛍光体としては、具体的には、放射線としてX線を用いて撮像する場合、ヨウ化セシウム(CsI)を含むものが好ましく、X線曝射時の発光スペクトルが400nm~700nmにあるCsI(Tl)(タリウムが添加されたヨウ化セシウム)を用いることが特に好ましい。なお、CsI(Tl)の可視光域における発光ピーク波長は565nmである。 Specifically, the phosphor used in the scintillator 56 preferably contains cesium iodide (CsI) when imaging using X-rays as radiation, and has an emission spectrum of 400 nm to 700 nm upon X-ray exposure. It is particularly preferred to use some CsI (Tl) (cesium iodide with thallium added). Note that the emission peak wavelength of CsI (Tl) in the visible light region is 565 nm.
 センサ部54は、上部電極60、下部電極62、および当該上下の電極間に配置された光電変換膜64を有し、光電変換膜64は、シンチレータ56が発する光を吸収して電荷が発生する有機光電変換材料により構成されている。 The sensor unit 54 includes an upper electrode 60, a lower electrode 62, and a photoelectric conversion film 64 disposed between the upper and lower electrodes. The photoelectric conversion film 64 absorbs light emitted from the scintillator 56 and generates electric charges. It is composed of an organic photoelectric conversion material.
 上部電極60は、シンチレータ56により生じた光を光電変換膜64に入射させる必要があるため、少なくともシンチレータ56の発光波長に対して透明な導電性材料で構成することが好ましく、具体的には、可視光に対する透過率が高く、抵抗値が小さい透明導電性酸化物(TCO「Transparent Conductive Oxide」)を用いることが好ましい。なお、上部電極60としてAuなどの金属薄膜を用いることもできるが、透過率を90%以上得ようとすると抵抗値が増大し易いため、TCOの方が好ましい。例えば、ITO、IZO、AZO、FTO、SnO、TiO、ZnO等を好ましく用いることができ、プロセス簡易性、低抵抗性、透明性の観点からはITOが最も好ましい。なお、上部電極60は、全画素で共通の一枚構成としてもよく、画素毎に分割してもよい。 Since it is necessary for the upper electrode 60 to cause the light generated by the scintillator 56 to enter the photoelectric conversion film 64, it is preferable that the upper electrode 60 be made of a conductive material that is transparent at least with respect to the emission wavelength of the scintillator 56. It is preferable to use a transparent conductive oxide (TCO “Transparent Conductive Oxide”) having a high transmittance for visible light and a low resistance value. Although a metal thin film such as Au can be used as the upper electrode 60, the TCO is preferable because it tends to increase the resistance when it is desired to obtain a transmittance of 90% or more. For example, ITO, IZO, AZO, FTO, SnO 2 , TiO 2 , ZnO 2 and the like can be preferably used, and ITO is most preferable from the viewpoint of process simplicity, low resistance, and transparency. Note that the upper electrode 60 may have a single configuration common to all pixels, or may be divided for each pixel.
 光電変換膜64は、有機光電変換材料を含み、シンチレータ56から発せられた光を吸収し、吸収した光に応じた電荷を発生する。このように有機光電変換材料を含む光電変換膜64であれば、可視域にシャープな吸収スペクトルを持ち、シンチレータ56による発光以外の電磁波が光電変換膜64に吸収されることがほとんどなく、X線等の放射線が光電変換膜64で吸収されることによって発生するノイズを効果的に抑制することができる。 The photoelectric conversion film 64 includes an organic photoelectric conversion material, absorbs light emitted from the scintillator 56, and generates electric charge according to the absorbed light. In this way, the photoelectric conversion film 64 including the organic photoelectric conversion material has a sharp absorption spectrum in the visible region, and electromagnetic waves other than light emitted by the scintillator 56 are hardly absorbed by the photoelectric conversion film 64, and X-rays are obtained. The noise generated by the radiation such as being absorbed by the photoelectric conversion film 64 can be effectively suppressed.
 光電変換膜64を構成する有機光電変換材料は、シンチレータ56で発光した光を最も効率よく吸収するために、その吸収ピーク波長が、シンチレータ56の発光ピーク波長と近いほど好ましい。有機光電変換材料の吸収ピーク波長とシンチレータ56の発光ピーク波長とが一致することが理想的であるが、双方の差が小さければシンチレータ56から発された光を十分に吸収することが可能である。具体的には、有機光電変換材料の吸収ピーク波長と、シンチレータ56の放射線に対する発光ピーク波長との差が、10nm以内であることが好ましく、5nm以内であることがより好ましい。 The organic photoelectric conversion material constituting the photoelectric conversion film 64 is preferably such that its absorption peak wavelength is closer to the emission peak wavelength of the scintillator 56 in order to absorb light emitted by the scintillator 56 most efficiently. Ideally, the absorption peak wavelength of the organic photoelectric conversion material matches the emission peak wavelength of the scintillator 56, but if the difference between the two is small, the light emitted from the scintillator 56 can be sufficiently absorbed. . Specifically, the difference between the absorption peak wavelength of the organic photoelectric conversion material and the emission peak wavelength with respect to the radiation of the scintillator 56 is preferably within 10 nm, and more preferably within 5 nm.
 このような条件を満たすことが可能な有機光電変換材料としては、例えばキナクリドン系有機化合物およびフタロシアニン系有機化合物が挙げられる。例えばキナクリドンの可視域における吸収ピーク波長は560nmであるため、有機光電変換材料としてキナクリドンを用い、シンチレータ56の材料としてCsI(Tl)を用いれば、上記ピーク波長の差を5nm以内にすることが可能となり、光電変換膜64で発生する電荷量をほぼ最大にすることができる。 Examples of the organic photoelectric conversion material that can satisfy such conditions include quinacridone organic compounds and phthalocyanine organic compounds. For example, since the absorption peak wavelength in the visible region of quinacridone is 560 nm, if quinacridone is used as the organic photoelectric conversion material and CsI (Tl) is used as the material of the scintillator 56, the difference in peak wavelength can be made within 5 nm. Thus, the amount of charge generated in the photoelectric conversion film 64 can be substantially maximized.
 各画素を構成するセンサ部54は、少なくとも下部電極62、光電変換膜64、および上部電極60を含んでいればよいが、暗電流の増加を抑制するため、電子ブロッキング膜66および正孔ブロッキング膜68の少なくともいずれかを設けることが好ましく、両方を設けることがより好ましい。 The sensor unit 54 constituting each pixel only needs to include at least the lower electrode 62, the photoelectric conversion film 64, and the upper electrode 60. In order to suppress an increase in dark current, the electron blocking film 66 and the hole blocking film are used. It is preferable to provide at least one of 68, and it is more preferable to provide both.
 電子ブロッキング膜66は、下部電極62と光電変換膜64との間に設けることができ、下部電極62と上部電極60間にバイアス電圧を印加したときに、下部電極62から光電変換膜64に電子が注入されて暗電流が増加してしまうのを抑制することができる。電子ブロッキング膜66には、電子供与性有機材料を用いることができる。 The electron blocking film 66 can be provided between the lower electrode 62 and the photoelectric conversion film 64. When a bias voltage is applied between the lower electrode 62 and the upper electrode 60, electrons are transferred from the lower electrode 62 to the photoelectric conversion film 64. It is possible to suppress the dark current from increasing due to the injection of. An electron donating organic material can be used for the electron blocking film 66.
 正孔ブロッキング膜68は、光電変換膜64と上部電極60との間に設けることができ、下部電極62と上部電極60間にバイアス電圧を印加したときに、上部電極60から光電変換膜64に正孔が注入されて暗電流が増加してしまうのを抑制することができる。正孔ブロッキング膜68には、電子受容性有機材料を用いることができる。 The hole blocking film 68 can be provided between the photoelectric conversion film 64 and the upper electrode 60. When a bias voltage is applied between the lower electrode 62 and the upper electrode 60, the hole blocking film 68 is transferred from the upper electrode 60 to the photoelectric conversion film 64. It is possible to suppress the increase in dark current due to the injection of holes. An electron-accepting organic material can be used for the hole blocking film 68.
 信号出力部52は、下部電極62に対応して、下部電極62に移動した電荷を蓄積するコンデンサ70と、コンデンサ70に蓄積された電荷を電気信号に変換して出力する電界効果型薄膜トランジスタ(Thin Film Transistor、以下、単に薄膜トランジスタという場合がある。)72が形成されている。コンデンサ70および薄膜トランジスタ72の形成された領域は、平面視において下部電極62と重なる部分を有しており、このような構成とすることで、各画素における信号出力部52とセンサ部54とが厚さ方向で重なりを有することとなる。なお、放射線検出器26(画素)の平面積を最小にするために、コンデンサ70および薄膜トランジスタ72の形成された領域が下部電極62によって完全に覆われていることが望ましい。 The signal output unit 52 corresponds to the lower electrode 62, a capacitor 70 that accumulates the charges transferred to the lower electrode 62, and a field effect thin film transistor (Thin) that converts the charges accumulated in the capacitor 70 into an electric signal and outputs the electric signal. (Film Transistor, hereinafter simply referred to as a thin film transistor) 72 is formed. The region in which the capacitor 70 and the thin film transistor 72 are formed has a portion that overlaps the lower electrode 62 in plan view. With this configuration, the signal output unit 52 and the sensor unit 54 in each pixel are thick. There will be overlap in the vertical direction. In order to minimize the plane area of the radiation detector 26 (pixel), it is desirable that the region where the capacitor 70 and the thin film transistor 72 are formed is completely covered with the lower electrode 62.
 図4は、本実施の形態に係る撮影システム16の制御ブロック図である。 FIG. 4 is a control block diagram of the imaging system 16 according to the present embodiment.
 コンソール30は、サーバー・コンピュータとして機能し、操作メニューや撮影された放射線画像等を表示するディスプレイ80と、複数のキーを備えると共に、各種の情報や操作指示が入力される操作パネル82と、を備えている。 The console 30 functions as a server computer, and includes a display 80 for displaying an operation menu, a captured radiographic image, and the like, and an operation panel 82 for inputting various information and operation instructions. I have.
 また、本実施の形態に係るコンソール30は、装置全体の動作を司るCPU84と、制御プログラムを含む各種プログラム等が予め記憶されたROM86と、各種データを一時的に記憶するRAM87と、各種データを記憶して保持するHDD(ハードディスク・ドライブ)88と、ディスプレイ80への各種情報の表示を制御するディスプレイドライバ92と、操作パネル82に対する操作状態を検出する操作入力検出部90と、を備えている。 The console 30 according to the present embodiment includes a CPU 84 that controls the operation of the entire apparatus, a ROM 86 that stores various programs including a control program in advance, a RAM 87 that temporarily stores various data, and various data. An HDD (Hard Disk Drive) 88 that stores and holds, a display driver 92 that controls display of various types of information on the display 80, and an operation input detector 90 that detects an operation state of the operation panel 82 are provided. .
 また、コンソール30は、無線通信により、画像処理装置23及び放射線発生装置24との間で後述する曝射条件等の各種情報の送受信を行うと共に、電子カセッテ20との間で画像データ等の各種情報の送受信を行うI/F(例えば、無線通信部)96及びI/O94を備えている。 Further, the console 30 transmits and receives various information such as an exposure condition described later between the image processing device 23 and the radiation generation device 24 by wireless communication, and various types of image data and the like with the electronic cassette 20. An I / F (for example, a wireless communication unit) 96 and an I / O 94 that transmit and receive information are provided.
 CPU84、ROM86、RAM87、HDD88、ディスプレイドライバ92、操作入力検出部90、I/O94、無線通信部96は、システムバスやコントロールバス等のバス98を介して相互に接続されている。従って、CPU84は、ROM86、RAM87、HDD88へのアクセスを行うことができると共に、ディスプレイドライバ92を介したディスプレイ80への各種情報の表示の制御、および無線通信部96を介した放射線発生装置24および電子カセッテ20との各種情報の送受信の制御を各々行うことができる。また、CPU84は、操作入力検出部90を介して操作パネル82に対するユーザの操作状態を把握することができる。 The CPU 84, ROM 86, RAM 87, HDD 88, display driver 92, operation input detection unit 90, I / O 94, and wireless communication unit 96 are connected to each other via a bus 98 such as a system bus or a control bus. Therefore, the CPU 84 can access the ROM 86, RAM 87, and HDD 88, controls display of various information on the display 80 via the display driver 92, and the radiation generator 24 via the wireless communication unit 96. Control of transmission and reception of various types of information with the electronic cassette 20 can be performed. Further, the CPU 84 can grasp the operation state of the user with respect to the operation panel 82 via the operation input detection unit 90.
 一方、画像処理装置23は、コンソール30との間で曝射条件等の各種情報を送受信するI/F(例えば無線通信部)100と、曝射条件に基づいて、電子カセッテ20及び放射線発生装置24を制御する画像処理制御ユニット102と、を備えている。また、放射線発生装置24は、放射線曝射源22Aからの放射線曝射を制御する放射線曝射制御ユニット22を備えている。 On the other hand, the image processing apparatus 23 includes an I / F (for example, a wireless communication unit) 100 that transmits and receives various types of information such as an exposure condition to and from the console 30, and the electronic cassette 20 and the radiation generation apparatus based on the exposure condition. 24, an image processing control unit 102 for controlling 24. The radiation generator 24 includes a radiation exposure control unit 22 that controls radiation exposure from the radiation exposure source 22A.
 画像処理制御ユニット102は、システム制御部104、パネル制御部106、画像処理制御部108を備え、相互にバス110によって情報をやりとりしている。パネル制御部106では、前記電子カセッテ20からの情報を、無線又は有線により受け付け、画像処理制御部108で画像処理が施される。 The image processing control unit 102 includes a system control unit 104, a panel control unit 106, and an image processing control unit 108, and exchanges information with each other via a bus 110. The panel control unit 106 receives information from the electronic cassette 20 wirelessly or by wire, and the image processing control unit 108 performs image processing.
 一方、システム制御部104は、コンソール30から曝射条件として管電圧、管電流等の情報を受信し、受信した曝射条件に基づいて放射線曝射制御ユニット22の放射線曝射源22Aから放射線Xを曝射させる制御を行う。 On the other hand, the system control unit 104 receives information such as a tube voltage and a tube current as an exposure condition from the console 30 and, based on the received exposure condition, the radiation X from the radiation exposure source 22A of the radiation exposure control unit 22. Control to expose.
 ところで、放射線画像を撮影するにあたり、全撮影領域の中から、注目するべき領域(関心領域)が抽出(設定)される場合がある。特に動画像撮影の場合、ほぼ静止している臓器や骨格が注目される画像である場合は少ない。言い換えれば、例えば、心臓等、鼓動している臓器、或いは、血管内を案内されて移動するカテーテル管の先端部等が注目される画像である場合が多い。カテーテル管の先端部の場合は、前記関心領域(以下、「ROI」という場合がある)を適宜変更し、当該先端部を追尾する場合がある。 By the way, in capturing a radiographic image, there are cases where a region to be noticed (region of interest) is extracted (set) from all the imaging regions. In particular, in the case of moving image shooting, there are few cases in which an organ or skeleton that is almost stationary is noticed. In other words, for example, the heart is often an image that attracts attention, such as a beating organ or the tip of a catheter tube that is guided and moved in a blood vessel. In the case of the distal end portion of the catheter tube, the region of interest (hereinafter sometimes referred to as “ROI”) may be appropriately changed to track the distal end portion.
 このため、本実施の形態における、撮影システム16では、撮影画像の動作状態に基づいて、自動的に関心領域を設定する機能を備えており、撮影指示があると、放射線画像撮影準備制御の後、関心領域を設定するための制御が実行される。 Therefore, the imaging system 16 according to the present embodiment has a function of automatically setting a region of interest based on the operation state of the captured image. Control for setting the region of interest is executed.
 また、本実施の形態の撮影システム16では、ABC「Auto Brightness Control」制御によって、被検者に曝射する放射線の放射線量をフィードバック補正して、適正な画像情報を得ることがなされている。ABC制御の原理は、電子カセッテ20から受信した階調信号に基づいて生成されるQL値の1フレーム分の平均値が、予め定められたしきい値(基準値)に収束するように放射線曝射源22Aから曝射される放射線量を調整するものであり、例えば、デジタルカメラやムービーカメラによる光量調整と同様である。 Also, in the imaging system 16 of the present embodiment, appropriate image information is obtained by performing feedback correction on the radiation dose of radiation exposed to the subject under the control of ABC “Auto Brightness Control”. The principle of ABC control is that radiation exposure is performed so that the average value of one frame of the QL value generated based on the gradation signal received from the electronic cassette 20 converges to a predetermined threshold value (reference value). This is for adjusting the amount of radiation exposed from the radiation source 22A, for example, the same as the light amount adjustment by a digital camera or a movie camera.
 しかしながら、ABC制御の撮影初期では、実際に曝射される放射線量と、適正な画像情報を得るための放射線量との間に大きな開きがあると、振幅の激しいフィードバック制御が繰り返され、徐々に収束していく。その分、放射線量を安定させるまでの時間が無駄となり、結果として、ROI設定時間が長くなり、放射線の場合、被検者に対して、放射線の被曝量が増加することになる要素となる。 However, at the initial stage of ABC control imaging, if there is a large gap between the radiation dose actually exposed and the radiation dose for obtaining appropriate image information, feedback control with intense amplitude is repeated and gradually Converge. Accordingly, the time until the radiation dose is stabilized is wasted, and as a result, the ROI setting time becomes long, and in the case of radiation, the radiation exposure dose increases for the subject.
 このROI設定完了までは所謂本撮影前であり、特に動画像撮影の場合には、ROIが設定し終えて、ROIが確定するまでは被検者への放射線被曝量を抑制することが好ましい。なお、本撮影中のROIの変更(例えば、カテーテル管の先端部の追尾するための変更等)は、ABC制御が安定しているため、放射線被曝を懸念する必要はない。 The completion of the ROI setting is before the so-called main imaging, and particularly in the case of moving image shooting, it is preferable to suppress the radiation exposure dose to the subject until the ROI is determined after the ROI has been set. Note that a change in ROI during the main imaging (for example, a change for tracking the distal end portion of the catheter tube, etc.) does not need to be concerned about radiation exposure because ABC control is stable.
 そこで、本実施の形態では、撮影指示があった場合に、動画撮影を開始するが、ABC制御を禁止し、かつROI設定期間中の放射線量を定常時よりも下げた状態で実行する構成とした。 Therefore, in the present embodiment, when a shooting instruction is given, moving image shooting is started, but ABC control is prohibited, and the radiation amount during the ROI setting period is executed in a state lower than the normal time. did.
 図5は、撮影システム16(主として、コンソール16、画像処理装置23、放射線発生装置24)における、放射線画像撮影(ROI設定を含む)のための制御系に特化したブロック図である。なお、このブロック図は、放射線画像撮影制御を機能別に分類したものであり、ハード構成を限定するものではない。即ち、以下で説明する図5に記載された各機能部(放射線量調整部120、階調信号解析部124、ダイナミックレンジ調整部126、静止画像生成部128、動画像編集部130、平均QL値演算部132、ABC制御部134、基準QL値メモリ136、関心領域設定部138、ROI確定前曝射制御部140)は、コンソール30、画像処理装置23、放射線発生装置24のいずれに配置されてもよい。 FIG. 5 is a block diagram specialized in a control system for radiographic image capturing (including ROI setting) in the imaging system 16 (mainly the console 16, the image processing device 23, and the radiation generating device 24). Note that this block diagram categorizes radiographic image capturing control by function, and does not limit the hardware configuration. That is, each functional unit (radiation dose adjustment unit 120, gradation signal analysis unit 124, dynamic range adjustment unit 126, still image generation unit 128, moving image editing unit 130, average QL value described in FIG. 5 described below. The calculation unit 132, the ABC control unit 134, the reference QL value memory 136, the region of interest setting unit 138, and the exposure control unit 140 before ROI determination are arranged in any of the console 30, the image processing device 23, and the radiation generation device 24. Also good.
 放射線曝射制御ユニット22では、放射線量調整部120によって調整された放射線量に基づいて、放射線曝射源22Aから放射線を曝射する。なお、放射線量調整部120は、出力される放射線量(エネルギー)を調整するものであるが、詳細については後述する。 The radiation exposure control unit 22 exposes radiation from the radiation exposure source 22A based on the radiation dose adjusted by the radiation dose adjustment unit 120. The radiation dose adjustment unit 120 adjusts the output radiation dose (energy), and details will be described later.
 放射線曝射源22Aから曝射された放射線は、臥位台36に横たわっている被検者40を通過して電子カセッテ20の放射線検出器26(図3参照)へ至る。放射線検出器26では、蛍光体膜56(図3参照)によって放射線量に応じた光量の光が発光し、TFT基板74によって光電変換される。 The radiation exposed from the radiation exposure source 22A passes through the subject 40 lying on the prone table 36 and reaches the radiation detector 26 (see FIG. 3) of the electronic cassette 20. In the radiation detector 26, the phosphor film 56 (see FIG. 3) emits light having a light amount corresponding to the radiation amount and is photoelectrically converted by the TFT substrate 74.
 電子カセッテ20のTFT基板74は、信号取得部122に接続されている。信号取得部122では、放射線曝射源22Aから曝射された放射に基づいて光電変換された信号を取得し、階調信号解析部124へ送出する。なお、この光電変換信号は、アナログ信号であってもよいし、電子カセッテ20内の制御部において、デジタル信号に変換した後でもよい。 The TFT substrate 74 of the electronic cassette 20 is connected to the signal acquisition unit 122. The signal acquisition unit 122 acquires a signal photoelectrically converted based on the radiation exposed from the radiation exposure source 22 </ b> A and sends it to the gradation signal analysis unit 124. The photoelectric conversion signal may be an analog signal or may be converted into a digital signal by the control unit in the electronic cassette 20.
 階調信号解析部124には、ダイナミックレンジ調整部126が接続されている。 A dynamic range adjustment unit 126 is connected to the gradation signal analysis unit 124.
 階調信号解析部124では、前記ダイナミックレンジ調整部126から受けたダイナミックレンジの圧縮パラメータ(以下、「圧縮率」といい、定常時は、圧縮率DRである。)に基づいて、光電変換信号のヒストグラム解析を行う。この結果、例えば、図10(A)に示される如く、階調(濃度)毎のデータカウント数(階調信号)を得る。この階調信号をQL値という場合がある。なお、ここでは、QL値を階調信号そのもの(生データ)とするが、階調信号そのものではなく、例えば、電子カセッテ20のコンデンサ70(図3参照)や、その他回路系の静電容量に起因するノイズ分を補正した後の値をQL値としてもよい。 In the tone signal analyzing unit 124, the compression parameter of the dynamic range received from the dynamic range adjustment unit 126 (hereinafter, referred to as "compression ratio", the steady state is the compression ratio DR N.) On the basis of the photoelectric conversion Perform a histogram analysis of the signal. As a result, for example, as shown in FIG. 10A, a data count number (gradation signal) for each gradation (density) is obtained. This gradation signal may be referred to as a QL value. Here, although the QL value is the gradation signal itself (raw data), it is not the gradation signal itself, but, for example, the capacitor 70 (see FIG. 3) of the electronic cassette 20 or other circuit system capacitance. A value after correcting the noise component may be used as the QL value.
 階調信号解析部124は、静止画像生成部128に接続されている。階調信号解析部124では、1フレーム分の階調信号が揃った時点で、逐次静止画像生成部128へ送出する。静止画像生成部128では、受け付けた階調信号に基づいて、1フレーム毎の画像データを生成する。なお、動画像撮影の場合と静止画撮影の場合とでは、電子カセッテ20から送られる光電変換信号そのものが異なり、例えば、本実施の形態のように、動画像撮影の場合には、転送速度を優先するため、ビニング処理がなされる。 The gradation signal analysis unit 124 is connected to the still image generation unit 128. The gradation signal analysis unit 124 sequentially transmits the gradation signals for one frame to the still image generation unit 128 when they are ready. The still image generation unit 128 generates image data for each frame based on the received gradation signal. Note that the photoelectric conversion signal itself sent from the electronic cassette 20 is different between the case of moving image shooting and the case of still image shooting. For example, as in this embodiment, in the case of moving image shooting, the transfer speed is set to be different. A binning process is performed to give priority.
 一方、仮に、本実施の形態の放射線画像撮影システム16を用いて、静止画撮影をする場合には、画質を優先するため、TFT基板74における最大の画素数に基づく画像データが生成される。 On the other hand, if still image shooting is performed using the radiation image shooting system 16 of the present embodiment, image data based on the maximum number of pixels on the TFT substrate 74 is generated in order to prioritize image quality.
 静止画像生成部128は、動画像編集部130に接続されている。動画像編集部130では、前記静止画像生成部128から逐次送出される1フレーム毎の画像データを組み合わせて、動画像を編集する。編集された動画像は、ディスプレイドライバ92を介して、ディスプレイ80に表示される。なお、前記静止画像生成部128は、ディスプレイドライバ92に接続されており、静止画像をディスプレイ80に表示することも可能となっている。 The still image generation unit 128 is connected to the moving image editing unit 130. The moving image editing unit 130 combines the image data for each frame sequentially transmitted from the still image generating unit 128 to edit the moving image. The edited moving image is displayed on the display 80 via the display driver 92. The still image generation unit 128 is connected to the display driver 92, and can display a still image on the display 80.
 動画像編集部130は、平均QL値演算部132に接続されている。この平均QL値演算部132では、動画像の各フレーム(或いは、適宜抜き取った1フレーム)のQL値の平均値を演算する。平均QL値演算部132での演算結果は、ABC制御部134へ送出される。 The moving image editing unit 130 is connected to the average QL value calculation unit 132. The average QL value calculation unit 132 calculates the average value of the QL values of each frame (or one frame appropriately extracted) of the moving image. The calculation result in the average QL value calculation unit 132 is sent to the ABC control unit 134.
 ABC制御部134には、基準QL値メモリ136が接続されている。ABC制御部134では、前記均QL値演算部132から受け付けたQL平均値と、基準QL値メモリ136から受け付けた基準QL値とを比較して、QL平均値が基準QL値に収束するための補正情報ΔXを生成する。この補正情報ΔXは、放射線曝射源22Aから曝射される放射線量(エネルギー)を増減するための補正係数として適用される。 A reference QL value memory 136 is connected to the ABC control unit 134. The ABC control unit 134 compares the QL average value received from the average QL value calculation unit 132 with the reference QL value received from the reference QL value memory 136, and converges the QL average value to the reference QL value. Correction information ΔX is generated. This correction information ΔX is applied as a correction coefficient for increasing or decreasing the radiation dose (energy) exposed from the radiation exposure source 22A.
 ABC制御部134で生成された補正情報ΔXは、前記放射線量調整部120へ送出される。放射線量調整部120では、放射線量Xが増減される(X←X×ΔX)。放射線量調整部120は、放射線量Xの初期値を記憶しており、曝射指示があった時点は当該初期値から曝射が開始される。これにより、動画像として生成される基となる光電変換信号を、階調信号を得るための過不足のない適正な範囲内に収めることができる。これは、光電変換信号と画像濃度との相関関係を示す特性図の変化率が大きい領域(例えば、感光材料で言えば、γ曲線の中間領域)であることを意味する。 The correction information ΔX generated by the ABC control unit 134 is sent to the radiation dose adjustment unit 120. In the radiation dose adjustment unit 120, the radiation dose XN is increased or decreased (X N ← X N × ΔX). Radiation dose adjustment unit 120 stores the initial value of the radiation amount X N, when there is exposure instructed exposure from the initial value is started. As a result, the photoelectric conversion signal that is the basis for generating the moving image can be within an appropriate range without excess or deficiency for obtaining the gradation signal. This means that it is a region where the rate of change in the characteristic diagram showing the correlation between the photoelectric conversion signal and the image density is large (for example, an intermediate region of the γ curve in the case of a photosensitive material).
 なお、本実施の形態では、放射線量Xの補正の際、補正情報ΔXを乗(除)算の係数としたが、加(減)算係数(X←X+ΔX)としてもよい。 In the present embodiment, when the correction of the radiation dose X N, but the coefficient of the correction information [Delta] X to the power of (removal) calculation may be acceleration (deceleration) calculated coefficients (X N ← X N + ΔX N) .
 ここで、前述したように、本実施の形態では、ROIを設定する必要がある。このため、動画像編集部130は、関心領域設定部138に接続されている。この関心領域設定部138では、動画像編集部130から受け付けた動画像データに基づいて、関心領域(ROI)を設定する。ROIの設定として、一般的な方法は、ある値以上の画素値をもつ画素を囲う方法であり、放射能が集積した臓器や病変全体を囲うのに適している。また、別の方法は、標準となる画像に、予めROIを定義しておきそれを対象画像に合わせこむ方法等がある。さらには、動画像の場合には、変化量の大きい箇所を抽出してもよい。 Here, as described above, in this embodiment, it is necessary to set the ROI. For this reason, the moving image editing unit 130 is connected to the region of interest setting unit 138. This region of interest setting unit 138 sets a region of interest (ROI) based on the moving image data received from the moving image editing unit 130. As a method of setting ROI, a general method is a method of surrounding pixels having a pixel value equal to or greater than a certain value, and is suitable for surrounding an organ or a lesion where radioactivity is accumulated. As another method, there is a method in which an ROI is defined in advance in a standard image and is matched with a target image. Furthermore, in the case of a moving image, a portion with a large amount of change may be extracted.
 関心領域設定部138では、ROIを設定する際に、ROI確定前曝射制御部140に対して、少なくともROIの設定開始時を示す開始信号、並びに設定完了時を示す完了信号を出力する。 When setting the ROI, the region-of-interest setting unit 138 outputs at least a start signal indicating the start of ROI setting and a completion signal indicating the completion of setting to the exposure control unit 140 before ROI determination.
 ROI確定前曝射制御部140は、前記放射線量調整部120、前記ABC制御部134、前記ダイナミックレンジ調整部126にそれぞれ接続されている。 The pre-ROI determination exposure control unit 140 is connected to the radiation dose adjustment unit 120, the ABC control unit 134, and the dynamic range adjustment unit 126, respectively.
 ROI確定前曝射制御部140からABC制御部134へは、ROI設定中は、ABC制御を禁止することを指示する制御禁止信号を出力する。 During the ROI setting, the control prohibition signal for instructing prohibition of the ABC control is output from the pre-ROI determination exposure control unit 140 to the ABC control unit 134.
 また、ROI確定前曝射制御部140から放射線量調整部120へは、前記初期値として記憶されている放射線量Xよりも低い放射線量(最小エネルギー)XROIに調整するための信号である最小エネルギー指示信号を出力する(XROI<X)。 Further, from the ROI determined before irradiation control unit 140 to the radiation amount adjuster 120, it is a signal for adjusting a lower dose than the dose X N stored as the initial value (minimum energy) X ROI A minimum energy instruction signal is output (X ROI <X N ).
 この結果、図10(B)及び図11(A)に示される如く、調信号解析部124における、光電変換信号のヒストグラム解析の結果は、設定されたダイナミックレンジの一部(QL値の低い領域)しか対象とならない。 As a result, as shown in FIG. 10B and FIG. 11A, the result of the histogram analysis of the photoelectric conversion signal in the modulation signal analysis unit 124 is a part of the set dynamic range (region with a low QL value). ) Only.
 そこで、ROI確定前曝射制御部140からダイナミックレンジ調整部126へは、ROI設定中は、ダイナミックレンジの圧縮率を、定常時の圧縮率DRから、当該圧縮率DRよりも圧縮率が高いROI設定時用の圧縮率DRROIとするための指示であるダイナミックレンジ圧縮率指示信号を出力する(DRROI>DR)。 Therefore, from the pre-ROI determination exposure control unit 140 to the dynamic range adjustment unit 126, during the ROI setting, the compression rate of the dynamic range is changed from the compression rate DR N in the steady state to the compression rate than the compression rate DR N. A dynamic range compression ratio instruction signal, which is an instruction for setting the compression ratio DR ROI for setting a high ROI, is output (DR ROI > DR N ).
 この結果、図11(B)に示される如く、光電変換信号のヒストグラム解析の結果が、ダイナミックレンジの全域が対象となる。 As a result, as shown in FIG. 11B, the result of the histogram analysis of the photoelectric conversion signal covers the entire dynamic range.
 すなわち、本実施の形態では、ROI設定中は、放射線曝射源22Aから曝射する放射線量(エネルギー)を低くし(放射線量Xから放射線量XROIへ)、かつ、低くした分、ダイナミックレンジの圧縮率を高くすることで(圧縮率DRからDRROIへ)、放射線量低下による被検者の被曝量軽減と、高精度のROI設定とを両立することが可能となる。 That is, in the present embodiment, during the ROI setting, the amount of radiation exposure from the radiation exposure source 22A (energy) lowered (from dose X N to radiation amount X ROI), and, correspondingly, which were low, the dynamic by increasing the compression ratio of the range (from the compression ratio DR N to DR ROI), and radiation exposure reduction of the subject to radiation amount decreases, it is possible to achieve both ROI setting precision.
 なお、関心領域設定部130におけるROIの設定が完了すると、完了信号がROI確定前曝射制御部140へ送出されることで、放射線量調整部120では、放射線量が初期値Xに設定され、ダイナミックレンジ調整部126では、圧縮率がDRに設定される。また、ABC制御部134によるABC制御も実行可能となる。 Incidentally, the setting of the ROI in the ROI setting unit 130 is completed, completion signal that is sent to ROI vested exposure control unit 140, the radiation amount adjuster 120, the radiation amount is set to an initial value X N in the dynamic range adjustment unit 126, the compression ratio is set to DR N. Also, ABC control by the ABC control unit 134 can be executed.
 以下に、本実施の形態の作用を図6~図9のフローチャートに従い説明する。 Hereinafter, the operation of the present embodiment will be described with reference to the flowcharts of FIGS.
 図6は、放射線画像撮影準備制御ルーチンを示すフローチャートである。 FIG. 6 is a flowchart showing the radiographic imaging preparation control routine.
 ステップ200では、コンソール30において撮影指示があったか否かが判断され、否定判定されるとこのルーチンは終了し、肯定判定されるとステップ202へ移行する。 In step 200, it is determined whether or not there has been a shooting instruction on the console 30, and if a negative determination is made, this routine ends. If an affirmative determination is made, the routine proceeds to step 202.
 ステップ202では、初期情報入力画面が表示される。すなわち、予め定められた初期情報入力画面をディスプレイ80により表示させるようにディスプレイドライバ92を制御し、ステップ204へ移行する。ステップ204では、所定情報の入力待ちを行う。 In step 202, an initial information input screen is displayed. That is, the display driver 92 is controlled to display a predetermined initial information input screen on the display 80, and the process proceeds to step 204. In step 204, input of predetermined information is waited.
 初期情報入力画面では、これから放射線画像の撮影を行う被検者の氏名、撮影対象部位、撮影時の姿勢、および撮影時の放射線Xの曝射条件(本実施の形態では、放射線Xを曝射する際の管電圧および管電流)の入力を促すメッセージと、これらの情報の入力領域が表示される。 In the initial information input screen, the name of the subject who will take a radiographic image, the part to be imaged, the posture at the time of radiography, and the exposure condition of the radiographic X at the time of radiography (in this embodiment, the radiation X is exposed Message for prompting the input of the tube voltage and tube current) and an input area for such information are displayed.
 初期情報入力画面がディスプレイ80に表示されると、撮影者は、撮影対象とする被検者の氏名、撮影対象部位、撮影時の姿勢、および曝射条件を、各々対応する入力領域に操作パネル82を介して入力する。 When the initial information input screen is displayed on the display 80, the photographer displays the name of the subject to be imaged, the region to be imaged, the posture at the time of imaging, and the exposure conditions in the corresponding input areas. Input via 82.
 撮影者は、被検者と共に放射線撮影室32に入室し、例えば、臥位である場合は、対応する臥位台36の保持部44に電子カセッテ20を保持させると共に放射線曝射源22Aを対応する位置に位置決めした後、被検者を所定の撮影位置に位置(ポジショニング)させる。なお、撮影対象部位が腕部、脚部等の電子カセッテ20を保持部に保持させない状態で放射線画像の撮影を行う場合は、当該撮影対象部位を撮影可能な状態に被検者、電子カセッテ20、および放射線曝射源22Aを位置決め(ポジショニング)させる。 The radiographer enters the radiography room 32 together with the subject. For example, when the radiographer is in the supine position, the radio cassette 20A is supported while the electronic cassette 20 is held in the holding unit 44 of the corresponding prone position table 36. After positioning at the position to be performed, the subject is positioned (positioned) at a predetermined imaging position. In addition, when radiography is performed in a state where the imaging target site does not hold the electronic cassette 20 such as an arm or a leg on the holding unit, the subject and the electronic cassette 20 are ready to capture the imaging target site. , And the radiation exposure source 22A is positioned (positioned).
 その後、撮影者は、放射線撮影室32を退室し、例えば、初期情報入力画面の下端近傍に表示されている終了ボタンを、操作パネル82を介して指定する。撮影者によって終了ボタンが指定されると、前記ステップ204が肯定判定となって、ステップ206に移行する。なお、図6のフローチャートでは、ステップ204の否定判定を無限ループとしたが、操作パネル82上に設けたキャンセルボタンの操作によって、強制終了してもよい。 Thereafter, the radiographer leaves the radiation imaging room 32 and designates, for example, an end button displayed near the lower end of the initial information input screen via the operation panel 82. When an end button is designated by the photographer, step 204 is affirmative and the process proceeds to step 206. In the flowchart of FIG. 6, the negative determination in step 204 is an infinite loop, but it may be forcibly terminated by operating a cancel button provided on the operation panel 82.
 ステップ206では、コンソール30から上記初期情報入力画面において入力された情報(以下、「初期情報」という。)を電子カセッテ20に無線通信部96を介して送信した後、次のステップ208へ移行して、前記初期情報に含まれる曝射条件を放射線発生装置24へ無線通信部96を介して送信することにより当該曝射条件を設定する。これに応じて放射線発生装置24の画像処理制御ユニット102は、受信した曝射条件での曝射準備を行う。 In step 206, information input on the initial information input screen from the console 30 (hereinafter referred to as “initial information”) is transmitted to the electronic cassette 20 via the wireless communication unit 96, and then the process proceeds to the next step 208. Then, the exposure condition included in the initial information is transmitted to the radiation generator 24 via the wireless communication unit 96 to set the exposure condition. In response to this, the image processing control unit 102 of the radiation generator 24 prepares for exposure under the received exposure conditions.
 次のステップ210では、ABC制御部134によるABC制御の起動を指示し、次いで、ステップ212へ移行して、放射線の曝射開始を指示する指示情報を放射線発生装置24へ無線通信部96を介して送信し、このルーチンは終了する。なお、このステップ210のABC制御の詳細については、図8のフローチャートを用い、後述する。 In the next step 210, the ABC control unit 134 instructs activation of ABC control, and then the process proceeds to step 212, and instruction information for instructing the start of radiation exposure is sent to the radiation generator 24 via the wireless communication unit 96. And the routine ends. The details of the ABC control in step 210 will be described later using the flowchart of FIG.
 次に、図7のフローチャートに従い、放射線画像撮影制御の流れを説明する。 Next, the flow of radiographic image capturing control will be described with reference to the flowchart of FIG.
 ステップ250では、放射線発生装置24(またはシステム制御部104)において曝射開始指示があった否かが判断され、否定判定された場合はこのルーチンは終了し、肯定判定された場合はステップ252へ移行する。 In step 250, it is determined whether or not the radiation generator 24 (or system control unit 104) has issued an exposure start instruction. If a negative determination is made, this routine ends. If an affirmative determination is made, the routine proceeds to step 252. Transition.
 ステップ252では、ROI設定部138により関心領域設定制御が実行され、当該関心領域設定が終了すると、ステップ254へ移行する。なお、このステップ252の関心領域設定制御の詳細については、図9のフローチャートを用い、後述する。 In step 252, the ROI setting unit 138 executes region-of-interest setting control, and when the region-of-interest setting ends, the process proceeds to step 254. Details of the region-of-interest setting control in step 252 will be described later using the flowchart of FIG.
 図7に示される如く、ステップ254では、放射線量調整部120により定常時放射線量(初期値)Xを読み出し、次いでステップ256へ移行して、放射線曝射制御ユニット22は、放射線発生装置24がコンソール30から受信した曝射条件に応じた管電圧および管電流での放射線Xの放射線曝射源22Aからの射出を開始する。放射線曝射源22Aから射出された放射線Xは、被検者を透過した後に電子カセッテ20に到達する。 As shown in FIG. 7, in step 254, a steady state dose by the radiation amount adjuster 120 reads out the (initial value) X N, then the routine proceeds to step 256, radiation exposure control unit 22, the radiation generator 24 Starts emission of radiation X from the radiation exposure source 22A at a tube voltage and a tube current according to the exposure conditions received from the console 30. The radiation X emitted from the radiation exposure source 22A reaches the electronic cassette 20 after passing through the subject.
 次のステップ258では、現在格納されている放射線量補正情報を読み出す。この放射線量補正情報は、ABC制御によって生成されるものであり、補正係数ΔXとして格納されている。 In the next step 258, the currently stored radiation dose correction information is read out. This radiation dose correction information is generated by ABC control and is stored as a correction coefficient ΔX.
 次のステップ260では、ABC制御部134によりABC制御に基づく補正処理が実行される。すなわち、電子カセッテ20から得た階調信号(QL値)に基づいて、関心領域画像のQL値の平均値を演算し、このQL値の平均値が予め定めたしきい値と比較され、しきい値に収束するように、放射線量にフィードバック制御される。 In the next step 260, the ABC control unit 134 executes correction processing based on ABC control. That is, based on the gradation signal (QL value) obtained from the electronic cassette 20, an average value of the QL values of the region of interest image is calculated, and the average value of the QL values is compared with a predetermined threshold value. The radiation dose is feedback controlled so as to converge to the threshold value.
 次のステップ262では、動画編集部130において動画像編集処理が実行されて、当該編集された動画像は、ステップ264において、ディスプレイ80に表示される(画像表示処理)。 In the next step 262, moving image editing processing is executed in the moving image editing unit 130, and the edited moving image is displayed on the display 80 in step 264 (image display processing).
 次のステップ266では、画像データ(動画像データ)をRISサーバー14(図1参照)へ病院内ネットワーク18を介して送信し、ステップ268へ移行する。ステップ268では、コンソール30において撮影終了の指示があったか否かが判断され、肯定判定されると、ステップ270で曝射を終了し、放射線画像撮影制御プログラムを終了する。なお、RISサーバー14へ送信された補正画像データはデータベース14Aに格納され、医師が撮影された放射線画像の読影や診断等を行うことが可能となる。 In the next step 266, image data (moving image data) is transmitted to the RIS server 14 (see FIG. 1) via the in-hospital network 18, and the process proceeds to step 268. In step 268, it is determined whether or not an instruction to end imaging is given on the console 30, and if an affirmative determination is made, exposure is terminated in step 270 and the radiographic image capturing control program is terminated. The corrected image data transmitted to the RIS server 14 is stored in the database 14A, so that a doctor can perform radiogram image interpretation and diagnosis.
 次に、図8に従い図6のステップ210で指示されて起動するABC制御の流れを説明する。なお、この図8のABC制御ルーチンは、前記図6及び図7のフローチャートとは独立して実行してもよい。 Next, the flow of ABC control that is instructed and started in step 210 of FIG. 6 will be described with reference to FIG. Note that the ABC control routine of FIG. 8 may be executed independently of the flowcharts of FIGS.
 ステップ300では、ABC制御部においてROI確定後の曝射制御中か否かが判断される。なお、これは、後述する図9のステップ320のABC制御禁止指示、ステップ338のABC制御禁止解除指示に基づいて判断される。 In step 300, it is determined in the ABC control unit whether or not the exposure control after ROI determination is being performed. This is determined based on an ABC control prohibition instruction in Step 320 and an ABC control prohibition release instruction in Step 338, which will be described later.
 ステップ300で否定判定された場合は、ROI設定中であると判断し、このルーチンは終了する。すなわち、ABC制御は実行されない。 If a negative determination is made in step 300, it is determined that ROI is being set, and this routine ends. That is, ABC control is not executed.
 また、ステップ300で肯定判定されると、ステップ302へ移行してダイナミックレンジ圧縮率を定常時の圧縮率DRに設定し、次いで、ステップ304へ移行して画像データを取り込み、ステップ306へ移行する。 Further, if an affirmative decision is made at step 300, the dynamic range compression ratio set in the compression ratio DR N in the steady state and proceeds to step 302, then captures the image data and proceeds to step 304, it proceeds to step 306 To do.
 ステップ306では、取り込んだ画像データから平均QL値を演算し、次いでステップ308へ移行して基準QL値を読み出す。 In step 306, the average QL value is calculated from the captured image data, and then the process proceeds to step 308 to read the reference QL value.
 次のステップ310では、取り込んだ画像データから平均QL値と、読み出した基準QL値とを比較し、補正の可否を判定してステップ312へ移行する。例えば、補正の可否の判定は、比較の結果において、差が所定以上の場合は予め定めた量の補正を行い当該差が所定未満であれば補正しないといった所謂オン/オフ判定であってもよいし、前記差に基づいて、予め定めた演算式(例えば、PID制御等に基づく演算式)による演算の解であってもよい。 In the next step 310, the average QL value from the captured image data is compared with the read reference QL value to determine whether correction is possible, and the process proceeds to step 312. For example, the determination as to whether correction is possible may be a so-called on / off determination in which a predetermined amount of correction is performed if the difference is greater than or equal to a predetermined value and no correction is made if the difference is less than a predetermined value. And based on the said difference, the solution of the calculation by a predetermined arithmetic expression (for example, arithmetic expression based on PID control etc.) may be sufficient.
 ステップ312では、ステップ310での比較、判定結果に基づいて、放射線量XROIの補正情報ΔXを生成し、次いで、ステップ314へ移行して、ステップ312で生成した補正情報ΔXを格納し、このルーチンは終了する。 In step 312, correction information ΔX of the radiation dose X ROI is generated based on the comparison and determination results in step 310, and then the process proceeds to step 314 to store the correction information ΔX generated in step 312. The routine ends.
 図9は、前記図7のステップ252において実行される関心領域設定制御ルーチンを示すフローチャートである。この関心領域設定制御ルーチンの実行が開始されると、ROI設定部138がROI確定前曝射制御部140に対して開始信号を出力する。 FIG. 9 is a flowchart showing a region-of-interest setting control routine executed in step 252 of FIG. When the execution of the region-of-interest setting control routine is started, the ROI setting unit 138 outputs a start signal to the exposure control unit 140 before ROI determination.
 ステップ320では、まず、ROI確定前曝射制御部140がABC制御部にABC制御の禁止を指示する。これにより、放射線曝射源22Aから曝射される放射線量はフィードバック制御されず、一定となる。 In step 320, first, the pre-ROI confirmation exposure control unit 140 instructs the ABC control unit to prohibit ABC control. As a result, the radiation dose exposed from the radiation exposure source 22A is constant without feedback control.
 次のステップ322では、ROI確定前曝射制御部140が関心領域設定時放射線量XROIを読み出す。この関心領域設定時放射線量XROIは、定常時放射線量Nよりも低い放射線量である(XROI<X)。 In the next step 322, the exposure control unit 140 before ROI determination reads the region-of-interest setting radiation dose X ROI . This region-of-interest setting radiation dose X ROI is lower than the steady-state radiation dose N (X ROI <X N ).
 次のステップ324では、ROI確定前曝射制御部140が関心領域設定時ダイナミックレンジ圧縮率DRROIを読み出す。この関心領域設定時ダイナミックレンジ圧縮率DRROIは、所定のダイナミックレンジ圧縮率DR(以下、「定常時ダイナミックレンジDR」という)よりも高い圧縮率である(DRROI>DR)。 In the next step 324, the ROI pre-determination exposure control unit 140 reads the dynamic range compression rate DR ROI when the region of interest is set. This region-of-interest setting dynamic range compression rate DR ROI is higher than a predetermined dynamic range compression rate DR N (hereinafter referred to as “steady-state dynamic range DR N ”) (DR ROI > DR N ).
 次のステップ326では、放射線量調整部120により前記放射線量XROIで曝射を開始し、ステップ328へ移行する。この場合、ABC制御が禁止されているため、この放射線量XROIは不変となる。 In the next step 326, the radiation dose adjusting unit 120 starts exposure with the radiation dose X ROI , and the process proceeds to step 328. In this case, since the ABC control is prohibited, the radiation dose X ROI remains unchanged.
 ステップ328では、ROI設定部138においてROI設定の処理を開始し、ステップ330へ移行する。 In step 328, ROI setting processing is started in the ROI setting unit 138, and the process proceeds to step 330.
 ステップ330では、動画像編集部130により動画像編集処理を実行し、次いでステップ332で画像表示処理を実行し、ステップ334へ移行する。 In step 330, the moving image editing process is executed by the moving image editing unit 130, and then the image display process is executed in step 332, and the process proceeds to step 334.
 ステップ334では、ROI設定部138において動画像から関心領域を設定できたか否かが判断され、否定判定された場合は、ステップ330へ戻り、動画像編集並びに画像表示を継続する。また、ステップ334で肯定判定された場合は、ROI設定が完了したと判断し、ステップ336へ移行して曝射を終了し、次いで、ステップ338へ移行して、ABC制御の禁止を解除してこのルーチンは終了する。 In step 334, it is determined whether or not the ROI setting unit 138 can set the region of interest from the moving image. If the determination is negative, the process returns to step 330 to continue moving image editing and image display. If the determination in step 334 is affirmative, it is determined that the ROI setting has been completed, the process proceeds to step 336 to end the exposure, and then the process proceeds to step 338 to cancel the prohibition of ABC control. This routine ends.
 ここで、図10(A)に示される如く、定常時の放射線量Xの下での光電変換信号を階調信号に変換するときのヒストグラムは、定常時のダイナミックレンジ圧縮率DR領域のほぼ全域に亘って分布している。言い換えれば、定常時のダイナミックレンジ圧縮率DRを設定するにあたり、定常時の放射線量Xに基づいて予測している。 Here, as shown in FIG. 10 (A), the histogram when converting the photoelectric conversion signal under radiation dose X N in the steady state to the tone signal, the dynamic range compression ratio DR N regions of the steady state It is distributed over almost the whole area. In other words, when setting the dynamic range compression ratio DR N in the steady state, it is predicted based on the radiation dose X N in the steady state.
 このため、前記図9のステップ322において放射線量を低下させると(XROI)、図10(B)及び図11(A)に示される如く、ヒストグラムの分布がQL値の低い領域に偏ることになる(図10(B)と図11(A)は同一の特性図である)。 For this reason, when the radiation dose is reduced in step 322 of FIG. 9 (X ROI ), the histogram distribution is biased toward a region having a low QL value as shown in FIGS. 10B and 11A. (FIG. 10B and FIG. 11A are the same characteristic diagram).
 そこで、図9のステップ324においてダイナミクレンジ圧縮率を高くした(DRROI)。この結果、図11(B)に示される如く、QL値の低い方に偏ったヒストグラムの分布に適合した領域のダイナミックレンジとすることができる。 Therefore, in step 324 in FIG. 9, the dynamic range compression ratio is increased (DR ROI ). As a result, as shown in FIG. 11B, the dynamic range of the region suitable for the histogram distribution biased toward the lower QL value can be obtained.
 以上説明した如く本実施の形態では、放射線画像撮影システム16において、動画像を撮影する場合、動画像である以上、被検者に静止画像撮影に比べて長い時間曝射を継続することになり、その分、被検者の被曝量を考慮する必要がある。 As described above, in the present embodiment, when a moving image is captured in the radiographic image capturing system 16, exposure to the subject is continued for a longer time compared to still image capturing as long as it is a moving image. Therefore, it is necessary to consider the exposure dose of the subject.
 そこで、本撮影前に実行される関心領域(ROI)の設定中は、放射線曝射源22Aから曝射する放射線量を極力抑え(定常時よりも低くし)、当該低くした放射線量に基づくQL値のヒクトグラムの分布に合わせて、ダイナミクレンジの圧縮率を定常時よりも高くした。このため、QL値の分布が偏ったとしても、ダイナミックレンジを無駄なく利用することができ、放射線量低下による被検者の被曝量軽減と、高精度のROI設定とを両立することができる。 Therefore, during the setting of the region of interest (ROI) to be executed before the main imaging, the radiation dose exposed from the radiation exposure source 22A is suppressed as much as possible (lower than the normal time), and the QL based on the lowered radiation dose is set. The dynamic range compression rate was set higher than in the steady state to match the distribution of the value gramogram. For this reason, even if the distribution of the QL value is biased, the dynamic range can be used without waste, and both reduction of the exposure dose of the subject due to the radiation dose reduction and high-precision ROI setting can be achieved.
 なお、本実施の形態では、関心領域の設定中は、被検者へ曝射される放射線量を抑制するために、放射線の放射エネルギーを定常よりも低くしたが、放射エネルギーを低くせず、放射線の曝射を間欠的にすることで、放射線曝射の所謂デューティを下げてもよい。これにより、単位時間当たり曝射する放射線量(累積値)を抑制することができる。なお、デューティを下げた分、電子カセッテ20内の放射線検出器26におけるフレームレートを低くすればよい。 In the present embodiment, during the setting of the region of interest, in order to suppress the radiation dose exposed to the subject, the radiation energy of radiation is lower than the steady state, but the radiation energy is not lowered, By making radiation exposure intermittent, the so-called duty of radiation exposure may be reduced. Thereby, the radiation dose (cumulative value) to be exposed per unit time can be suppressed. Note that the frame rate in the radiation detector 26 in the electronic cassette 20 may be lowered by the amount of the reduced duty.
 また、被検者へ曝射される放射線量を抑制する手段として、放射線曝射源22Aからの放射線量が変えずに、被検者との間に一時的(関心領域設定中)に放射線フィルタを介在させてもよい。 Further, as a means for suppressing the radiation dose to be exposed to the subject, the radiation filter is temporarily (within the region of interest setting) between the subject and the subject without changing the radiation dose from the radiation exposure source 22A. May be interposed.
 なお、放射線フィルタには、例えば、放射線曝射源22Aの曝射面に設置可能な所謂絞り機構部を含むものとする。すなわち、通常のカメラで言えば、ND(減光)フィルタをレンジに取り付けること、絞りを調整することは、露出を調整(低減)する役目としては同じである。なお、放射線フィルタは、例えば、特開2001-190531号公報に、放射線フィルタが開示されているが、絞り機構部は、放射線の種類等によって、事実上、放射線フィルタが実用化できない場合の代用として適用可能である。 The radiation filter includes, for example, a so-called diaphragm mechanism that can be installed on the radiation surface of the radiation radiation source 22A. In other words, with a normal camera, attaching an ND (darkening) filter to the range and adjusting the aperture are the same in terms of the role of adjusting (reducing) exposure. As a radiation filter, for example, Japanese Patent Application Laid-Open No. 2001-190531 discloses a radiation filter. However, the diaphragm mechanism is a substitute for a case where the radiation filter cannot be practically used depending on the type of radiation. Applicable.
 さらに、本実施の形態では、電子カセッテ20内の放射線検出器26が、検出画素が二次元配列された所謂エリアセンサであるが、静止画像ほどフレームレートの高速化が要求されない動画像専用として、主走査方向画素が配列されたラインセンサと、このラインセンサを副走査方向へ移動させる走査機構部とを備え、走査機構部の走査で時系列で二次元の画像を取得する機能を備えた新たな電子カセッテを製作してもよい。また、図2に示す立位台42或いは臥位台36に、ラインセンサと走査機構部を内蔵してもよい。 Furthermore, in the present embodiment, the radiation detector 26 in the electronic cassette 20 is a so-called area sensor in which detection pixels are two-dimensionally arranged, but only for a moving image that does not require a higher frame rate than a still image, Newly equipped with a line sensor in which pixels in the main scanning direction are arranged and a scanning mechanism unit that moves the line sensor in the sub-scanning direction, and a function of acquiring a two-dimensional image in time series by scanning of the scanning mechanism unit An electronic cassette may be manufactured. Further, a line sensor and a scanning mechanism unit may be built in the standing table 42 or the standing table 36 shown in FIG.
 ラインセンサの場合、例えば、関心領域(ROI)が設定された後、動画像を当該ROI領域内に特定すれば、少なくとも副走査範囲を減縮することができるため、検出する階調信号の情報量を軽減することができる。 In the case of a line sensor, for example, after a region of interest (ROI) is set, if a moving image is specified in the ROI region, at least the sub-scanning range can be reduced. Can be reduced.
 また、本実施の形態では、関心領域(ROI)の設定中は、放射線曝射源22Aからの放射線の放射エネルギーを定常よりも低い、一定の放射エネルギーとしたが、関心領域設定中に徐々に変化(例えば、増加)させてもよい。 In the present embodiment, while setting the region of interest (ROI), the radiation energy of the radiation from the radiation exposure source 22A is set to a constant radiation energy that is lower than the steady state. It may be changed (eg increased).
 また、これに伴い、ダイナミックレンジの圧縮率も徐々に変化させてもよい。 Also, along with this, the compression ratio of the dynamic range may be gradually changed.
 これにより、予め定めた一定の放射エネルギーが、被検者(対象物)に起因して関心領域の設定に不適であった場合があっても、確実に関心領域を設定することができる。なお、変化は、連続的、段階的の何れでもよいし、指示があったときのみ変化させてもよい。また、放射エネルギーの変化と、ダイナミックレンジの圧縮率の変化とに相関を持たせたが、独立した制御を行ってもよい。 This makes it possible to reliably set the region of interest even when the predetermined fixed radiant energy may be inappropriate for setting the region of interest due to the subject (object). The change may be continuous or stepwise, and may be changed only when an instruction is given. Moreover, although the change of the radiant energy is correlated with the change of the compression ratio of the dynamic range, independent control may be performed.
 また、上記の実施の形態では、本発明の放射線としてX線を適用した場合について説明したが、本発明はこれに限定されるものではなく、例えば、α線、γ線等の他の放射線が含まれる。 In the above embodiment, the case where X-rays are applied as the radiation of the present invention has been described. However, the present invention is not limited to this. For example, other radiation such as α-rays and γ-rays included.

Claims (13)

  1.  設定された定常範囲の放射線エネルギーの放射線を被検体に向けて曝射する放射線曝射部から曝射され、かつ前記被検体を通過した放射線量を、複数の画素を備えた放射線検出器で受け、当該画素毎に受ける放射線量に応じた階調信号を出力する放射線画像撮影部と、
     前記放射線画像撮影部から階調信号を取得して、所定のダイナミックレンジの下で当該階調信号を読み取り、1フレーム毎の静止画像情報を生成すると共に、前記静止画像を連続的に撮影することで前記被検体の動画像を生成する動画像情報生成部と、
     所定の制御周期で、前記放射線曝射部から曝射する前記放射線の放射線エネルギーの設定値をフィードバック制御する制御部と、
     前記制御部によるフィードバック制御を禁止すると共に、前記被検体の被曝量を前記定常範囲での放射線エネルギーによる被曝量よりも抑制した状態で実行され、前記動画像情報生成部で生成された画像の一部を関心領域として設定する関心領域設定部と、
    を有する放射線動画像撮影装置。
    A radiation detector having a plurality of pixels receives a radiation dose that is emitted from a radiation exposure unit that emits radiation of a set radiation energy in a normal range toward the subject and passes through the subject. A radiographic image capturing unit that outputs a gradation signal corresponding to the radiation dose received for each pixel;
    Acquiring a gradation signal from the radiation image capturing unit, reading the gradation signal under a predetermined dynamic range, generating still image information for each frame, and continuously capturing the still image A moving image information generating unit for generating a moving image of the subject;
    A control unit that feedback-controls a set value of radiation energy of the radiation to be exposed from the radiation exposure unit at a predetermined control period;
    One of the images generated by the moving image information generation unit is executed in a state where the feedback control by the control unit is prohibited and the exposure amount of the subject is suppressed more than the exposure amount by the radiation energy in the steady range. A region-of-interest setting unit that sets a region as a region of interest;
    A radiological image capturing apparatus having
  2.  前記被曝量の抑制が、前記放射線曝射部に対して指示する放射線エネルギーを定常範囲よりも低くすることである請求項1記載の放射線動画像撮影装置。 The radiation moving image capturing apparatus according to claim 1, wherein the suppression of the exposure dose is to make radiation energy instructed to the radiation exposure unit lower than a steady range.
  3.  前記被曝量の抑制が、定常時よりも低いフレームレートとすることである請求項1又は請求項2記載の放射線動画像撮影装置。 The radiological image capturing apparatus according to claim 1 or 2, wherein the exposure dose is suppressed to a frame rate lower than that in a steady state.
  4.  前記被曝量の抑制が、前記放射線曝射部と前記被検体との間に、放射線をカットするフィルタを配置することである請求項1~請求項3の何れか1項記載の放射線動画像撮影装置 The radiological moving image photographing according to any one of claims 1 to 3, wherein the exposure dose is suppressed by disposing a filter for cutting radiation between the radiation exposure unit and the subject. apparatus
  5.  前記被曝量が抑制され、かつ前記フィードバック制御が禁止されている間は、前記ダイナミックレンジの圧縮のパラメータである前記階調信号に対する前記画像情報の変化率を、フィードバック制御中よりも大きくする、請求項1~請求項4の何れか1項記載の放射線動画像撮影装置。 While the exposure dose is suppressed and the feedback control is prohibited, the rate of change of the image information with respect to the gradation signal, which is a parameter for compression of the dynamic range, is made larger than during feedback control. The radiation moving image capturing apparatus according to any one of claims 1 to 4.
  6.  前記関心領域設定部により関心領域が設定された後は、前記制御部によるフィードバック制御の対象を、当該関心領域内の画像とする請求項1~請求項5の何れか1項記載の放射線動画像撮影装置。 The radiological moving image according to any one of claims 1 to 5, wherein after the region of interest is set by the region of interest setting unit, an object of feedback control by the control unit is an image in the region of interest. Shooting device.
  7.  被検体に向けて、定常範囲での放射線エネルギーによる被曝量よりも抑制した放射線エネルギーで放射線を曝射し、被検体を通過した放射線量を、複数の画素を備えた放射線検出器で受け、
     当該画素毎に受ける放射線量に応じた階調信号に基づいて、1フレーム毎の静止画像情報を生成し、
     前記静止画像を連続的に撮影することで前記被検体の動画像を生成し、
     生成された画像の一部を関心領域として設定し、
     当該関心領域を設定した後、前記放射線エネルギーの抑制を解除して、所定の制御周期で、曝射する前記放射線の放射線エネルギーの設定値をフィードバック制御する処理を開始する放射線動画像撮影装置用関心領域設定方法。
    Towards the subject, radiation is irradiated with radiation energy that is less than the exposure amount due to radiation energy in a steady range, and the radiation amount that has passed through the subject is received by a radiation detector having a plurality of pixels,
    Based on a gradation signal corresponding to the radiation dose received for each pixel, generate still image information for each frame,
    A moving image of the subject is generated by continuously capturing the still images,
    Set a part of the generated image as a region of interest,
    After setting the region of interest, the radiation energy suppression apparatus is started to release the suppression of the radiation energy and start a feedback control of the radiation energy setting value of the radiation to be exposed at a predetermined control cycle. Area setting method.
  8.  前記被曝量の抑制が、前記放射線曝射部に対して指示する放射線エネルギーを定常範囲よりも低くすることである請求項7記載の放射線動画像撮影装置用関心領域設定方法。 The method of setting a region of interest for a radiographic image capturing apparatus according to claim 7, wherein the suppression of the exposure dose is to make the radiation energy instructed to the radiation exposure unit lower than a steady range.
  9.  前記被曝量の抑制が、定常時よりも低いフレームレートとすることである請求項9又は請求項8記載の放射線動画像撮影装置用関心領域設定方法。 The method of setting a region of interest for a radiographic image capturing apparatus according to claim 9 or 8, wherein the exposure dose is controlled to be a frame rate lower than that in a steady state.
  10.  前記フィードバック制御が禁止されている間は、前記階調信号を読み取るダイナミックレンジの圧縮のパラメータを、フィードバック制御中のダイナミックレンジの圧縮のパラメータとする請求項7~請求項9の何れか1項記載の放射線動画像撮影装置用関心領域設定方法。 10. The dynamic range compression parameter for reading the gradation signal is set as a dynamic range compression parameter during feedback control while the feedback control is prohibited. Region-of-interest setting method for radiographic image capturing apparatus.
  11.  前記請求項1~請求項6の何れか1項記載の放射線動画像撮影装置と、
     診断情報や施設予約の入力、閲覧、並びに放射線動画像の撮影依頼や撮影予約を行う端末装置と、
     前記端末装置からの撮影依頼を受け付け、前記放射線動画像撮影装置における放射線画像の撮影スケジュールを管理すると共に、撮影された放射線動画像を一括管理するサーバーと、
    を有する放射線画像撮影システム。
    The radiological moving image capturing apparatus according to any one of claims 1 to 6,
    A terminal device for inputting and browsing diagnostic information and facility reservations, as well as radiographic image capturing requests and imaging reservations;
    A server that accepts an imaging request from the terminal device, manages a radiographic imaging schedule in the radiographic video imaging device, and collectively manages radiographic images captured;
    A radiographic imaging system comprising:
  12.  コンピュータを、前記請求項1~請求項6の何れか1項記載の放射線動画像撮影装置の動画像情報生成部、制御部並びに関心領域設定部として機能させる放射線動画像撮影制御プログラム。 7. A radiation moving image photographing control program for causing a computer to function as a moving image information generating unit, a control unit, and a region of interest setting unit of the radiation moving image photographing apparatus according to any one of claims 1 to 6.
  13.  コンピュータに放射線動画像撮影を実行させるプログラムを記憶した持続性コンピュータ可読記憶媒体であって、前記放射線動画像撮影処理が、
     被検体に向けて、定常範囲での放射線エネルギーによる被曝量よりも抑制した放射線エネルギーで放射線を曝射し、被検体を通過した放射線量を、複数の画素を備えた放射線検出器で受けることで取得された、当該画素毎に受ける放射線量に応じた階調信号に基づいて、1フレーム毎の静止画像情報を生成し、
     前記静止画像を連続的に撮影することで前記被検体の動画像を生成し、
     生成された画像の一部を関心領域として設定し、
     当該関心領域を設定した後、前記放射線エネルギーの抑制を解除して、所定の制御周期で、曝射する前記放射線の放射線エネルギーの設定値をフィードバック制御する処理を開始すること
     を含む、記憶媒体。
    A persistent computer-readable storage medium storing a program for causing a computer to execute radiographic image capturing, wherein the radiographic image capturing process includes:
    By irradiating radiation toward the subject with radiation energy that is less than the radiation dose due to radiation energy in the steady range, and receiving the radiation amount that has passed through the subject with a radiation detector that has multiple pixels. Based on the acquired gradation signal corresponding to the radiation dose received for each pixel, generating still image information for each frame,
    A moving image of the subject is generated by continuously capturing the still images,
    Set a part of the generated image as a region of interest,
    After setting the region of interest, releasing the suppression of the radiation energy, and starting a process for feedback control of the set value of the radiation energy of the radiation to be exposed in a predetermined control cycle.
PCT/JP2012/066049 2011-09-21 2012-06-22 Radiographic moving image shooting device, method for setting region-of-interest for radiographic moving image shooting device, radioactive moving image shooting system, radiographic moving image shooting control program, and memory medium for radiographic moving image shooting control program WO2013042415A1 (en)

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