WO2012114766A1 - Stereoscopic radiological image generating device, method, and program - Google Patents

Stereoscopic radiological image generating device, method, and program Download PDF

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Publication number
WO2012114766A1
WO2012114766A1 PCT/JP2012/001268 JP2012001268W WO2012114766A1 WO 2012114766 A1 WO2012114766 A1 WO 2012114766A1 JP 2012001268 W JP2012001268 W JP 2012001268W WO 2012114766 A1 WO2012114766 A1 WO 2012114766A1
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radiation
imaging
image
radiographic image
irradiated
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PCT/JP2012/001268
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French (fr)
Japanese (ja)
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孝夫 桑原
大田　恭義
靖子 八尋
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富士フイルム株式会社
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/50—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment specially adapted for specific body parts; specially adapted for specific clinical applications
    • A61B6/502—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment specially adapted for specific body parts; specially adapted for specific clinical applications for diagnosis of breast, i.e. mammography
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
    • A61B6/022—Stereoscopic imaging
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/54—Control of apparatus or devices for radiation diagnosis
    • A61B6/542—Control of apparatus or devices for radiation diagnosis involving control of exposure
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/54—Control of apparatus or devices for radiation diagnosis
    • A61B6/547—Control of apparatus or devices for radiation diagnosis involving tracking of position of the device or parts of the device

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  • the present invention relates to a technique for generating radiographic images for left and right eyes for performing stereoscopic viewing using binocular parallax.
  • stereoscopic viewing can be performed using parallax by displaying a combination of a plurality of images.
  • a stereoscopically viewable image hereinafter referred to as a stereoscopic image or a stereo image
  • a stereoscopic image or a stereo image is generated based on a plurality of images having parallax obtained by photographing the same subject from different positions.
  • stereoscopic images is used not only in the fields of digital cameras and televisions, but also in the field of radiographic imaging. That is, the patient is irradiated with radiation from different directions, the radiation transmitted through the subject is detected by a radiation image detector, and a plurality of radiation images having parallax are obtained, and these radiations are acquired. A stereoscopic image is generated based on the image. By generating a stereoscopic image in this way, a radiographic image having a sense of depth can be observed, and a radiographic image more suitable for diagnosis can be observed (see, for example, Patent Document 1).
  • the number of images to be acquired is more than doubled compared to a normal radiographic imaging apparatus that acquires only a two-dimensional image. There is a problem that the amount increases.
  • the present applicant has proposed that the radiation dose at the time of photographing one of the stereo images is lower than that of the other image (US provisional application 61 / 385,374). This is based on the new knowledge found by the present applicant that stereoscopic display is possible even when the image quality of the left and right images does not match during stereoscopic display.
  • an image captured at a low dose has a lower image quality than an image captured at a high dose, so that stereoscopic display may be difficult, and degradation of diagnostic accuracy may be a problem.
  • the present invention has been made in view of the above circumstances, and provides a stereoscopic radiographic image generation apparatus, method, and program that achieves both reduction in patient exposure and maintenance of stereoscopic display quality. With the goal.
  • the present invention is based on the finding that the stereoscopic display is possible even when different image processing is performed on the left and right images in the stereoscopic display, which is found in association with the above-mentioned new knowledge. is there.
  • the stereoscopic radiographic image generation apparatus of the present invention includes a radiation source capable of emitting radiation from two different imaging directions, a radiation detector for detecting the irradiated radiation, and an output from the radiation detector.
  • An image generation unit that reads the radiographic image signal that is generated and generates a radiographic image based on the radiographic image signal, and a radiation dose that is irradiated from a radiation source during imaging in one of the two imaging directions is 2
  • an image processing unit that performs image processing for suppressing graininess.
  • the stereoscopic radiographic image generation method of the present invention includes a step of irradiating radiation from a predetermined first imaging direction, a step of detecting the irradiated radiation with a radiation detector, and a first output from the radiation detector. Reading the radiation image signal of the first and generating a first radiation image based on the first radiation image signal, irradiating radiation from a second imaging direction different from the first imaging direction, and irradiation Detecting the emitted radiation with a radiation detector, and reading a second radiation image signal output from the radiation detector and generating a second radiation image based on the second radiation image signal.
  • the amount of radiation to be irradiated at the time of photographing in one of the photographing directions is irradiated at the time of photographing in the other of the photographing directions.
  • a step of controlling a radiation source that emits radiation so as to be lower than a radiation dose, and a step of performing image processing for suppressing graininess on a radiation image generated by imaging in one imaging direction It is characterized by having.
  • the stereoscopic radiographic image generation program of the present invention includes a radiation source capable of irradiating radiation from two different imaging directions, a radiation detector for detecting the irradiated radiation, and a radiation image signal output from the radiation detector.
  • the amount of radiation to be irradiated at the time of imaging in one of the imaging directions to a stereoscopic radiographic image generation apparatus including an image generation unit that generates a radiographic image based on the radiographic image signal ,
  • a step of controlling a radiation source for irradiating radiation so as to be lower than a radiation dose to be irradiated at the time of imaging in the other imaging direction of each imaging direction, and radiation generated by imaging in one imaging direction A step of performing image processing for suppressing graininess on the image.
  • image processing for suppressing graininess include unsharpening processing and processing for reducing the enhancement degree of high-frequency components.
  • the image processing for suppressing the graininess may be performed with different processing intensities for both of the radiographic images obtained in the respective photographing directions.
  • the granularity is stronger than the radiographic image obtained in the other (higher radiation dose) imaging direction. It is preferable to perform image processing to suppress the property.
  • the angle formed by the imaging direction of the other of the two imaging directions (the one with the higher radiation dose) and the direction orthogonal to the detection surface of the radiation detector is one of the two imaging directions ( It is preferable to make it smaller than the angle formed by the direction perpendicular to the imaging direction of the lower radiation dose). At this time, it is preferable that the angle formed by the other imaging direction (the one with the higher radiation dose) and the direction perpendicular to the detection surface of the radiation detector is 0 °.
  • the radiation dose to be irradiated from the radiation source during one imaging in the two imaging directions Since the radiation dose emitted from the radiation source during imaging in the other of the directions is set lower, the exposure dose of the patient when acquiring a stereo image can be reduced, and imaging in one imaging direction can be performed.
  • the quality of stereoscopic display using a stereo image is also maintained by performing image processing that suppresses graininess on the radiation image generated in step (b).
  • FIG. 1 Schematic configuration diagram of a stereo breast image radiographing display system using an embodiment of a radiographic image radiographing display system of the present invention
  • FIG. 1 The figure which looked at the arm part of the stereo breast image radiographing display system shown in FIG. 1 from the right direction of FIG.
  • the block diagram which shows schematic structure inside the computer of the stereo breast image radiographing display system shown in FIG.
  • FIG. 1 is a diagram showing a schematic configuration of a breast image radiographing display system
  • FIG. 2 is a diagram of an arm portion of the stereo mammography radiographing display system shown in FIG. 1, viewed from the right side in FIG. 1, and
  • FIG. It is a block diagram which shows schematic structure inside the computer of a breast image radiography display system.
  • a breast image radiographing display system 1 of the present embodiment includes a mammography apparatus 10, a computer 8 connected to the mammography apparatus 10, a monitor 9 connected to the computer 8, and an input unit. 7.
  • the mammography apparatus 10 includes a base 11, a rotary shaft 12 that can move in the vertical direction (Z direction) with respect to the base 11, and can rotate.
  • the arm part 13 connected with the base 11 is provided.
  • FIG. 2 shows the arm 13 viewed from the right direction in FIG.
  • the arm section 13 has an alphabet C shape, and a radiation table 16 is attached to one end of the arm section 13 so as to face the imaging table 14 at the other end.
  • the rotation and vertical movement of the arm unit 13 are controlled by an arm controller 31 incorporated in the base 11.
  • a radiation image detector 15 (corresponding to a radiation detector) such as a flat panel detector and a detector controller 33 that controls reading of a charge signal from the radiation image detector 15 are provided. Yes. Further, inside the imaging table 14, a charge amplifier that converts the charge signal read from the radiation image detector 15 into a voltage signal, a correlated double sampling circuit that samples the voltage signal output from the charge amplifier, A circuit board provided with an AD conversion unit for converting a voltage signal into a digital signal is also installed. The detector controller 33 and the circuit board described above and the computer 8 constitute an image generating means.
  • the photographing table 14 is configured to be rotatable with respect to the arm unit 13, and even when the arm unit 13 rotates with respect to the base 11, the direction of the photographing table 14 is fixed to the base 11. can do.
  • the radiographic image detector 15 can repeatedly perform recording and reading of radiographic images, and a so-called direct conversion type radiographic image detector that directly receives radiation and generates charges may be used.
  • a so-called indirect conversion type radiation image detector that converts radiation once into visible light and converts the visible light into a charge signal may be used.
  • a radiation image signal readout method a radiation image signal is read out by turning on / off a TFT (thin film transistor) switch, or by irradiating reading light. It is desirable to use a so-called optical readout system from which a radiation image signal is read out, but the present invention is not limited to this, and other systems may be used.
  • the radiographic image signal output from the radiographic image detector 15 is AD-converted into radiographic image data.
  • a radiation source 17 and a radiation source controller 32 are accommodated in the radiation irradiation unit 16.
  • the radiation source controller 32 controls the timing of irradiating radiation from the radiation source 17 and the radiation generation conditions (tube voltage, tube current, time, tube current time product, etc.) in the radiation source 17.
  • a compression plate 18 that is disposed above the imaging table 14 and presses and compresses the breast M, a support portion 20 that supports the compression plate 18, and a support portion 20 that extends in the vertical direction.
  • a moving mechanism 19 for moving in the (Z direction) is provided. The position of the compression plate 18 and the compression pressure are controlled by the compression plate controller 34.
  • the computer 8 includes a central processing unit (CPU) and a storage device such as a semiconductor memory, a hard disk, and an SSD.
  • a processing unit 8c is configured.
  • the controller 8a outputs predetermined control signals to the various controllers 31 to 34 to control the entire system. A specific control method will be described in detail later.
  • the radiation image storage unit 8b stores radiation image data for each imaging angle acquired by the radiation image detector 15.
  • the image processing unit 8c is for performing various image processing on the radiation image data. The processing for suppressing graininess according to the present invention is also performed by the image processing unit 8c.
  • the input unit 7 is composed of a pointing device such as a keyboard and a mouse, for example, and accepts input of shooting conditions and operation instructions by the photographer.
  • the monitor 9 is configured to display a stereo image by using the two radiographic image data output from the computer 8 to display the radiographic image for each imaging direction as a two-dimensional image.
  • radiographic images based on two radiographic image data are displayed using two screens, and one of the radiographic images is observed by using a half mirror, a polarizing glass, or the like. It is possible to adopt a configuration in which a stereo image is displayed by being incident on the right eye of the observer and the other radiation image is incident on the left eye of the observer.
  • two radiographic images may be displayed in a superimposed manner while being shifted by a predetermined amount of parallax, and this may be configured to generate a stereo image by observing with a polarizing glass, or a parallax barrier method and a lenticular method
  • a stereo image may be generated by displaying two radiation images on a stereoscopically viewable 3D liquid crystal.
  • the device that displays a stereo image and the device that displays a two-dimensional image may be configured separately, or may be configured as the same device if they can be displayed on the same screen.
  • the breast M is set on the imaging table 14, and the breast M is compressed with a predetermined pressure by the compression plate 18.
  • various imaging conditions including a combination of an angle formed by two different imaging directions (hereinafter referred to as a convergence angle ⁇ ) and an imaging angle ⁇ ′ constituting the convergence angle ⁇ are input in the input unit 7, An instruction to start shooting is input.
  • the control unit 8 a outputs information about the convergence angle ⁇ and the imaging angle ⁇ ′ constituting the convergence angle ⁇ to the arm controller 31.
  • the unit 7 can set an arbitrary convergence angle ⁇ .
  • the convergence angle ⁇ is preferably set to 4 ° or more and 15 ° or less because it is difficult to perform appropriate stereoscopic viewing if the convergence angle ⁇ is too small or too large.
  • the combination of the shooting angles ⁇ ′ is not particularly limited as long as one shooting angle ⁇ ′ is smaller than the other shooting angle ⁇ ′.
  • the one shooting angle ⁇ ′ described above, that is, the shooting angle ⁇ ′ for shooting an image for two-dimensional observation is preferably 0 °. This is because an image taken from the front of the radiation image detector 15 is most suitable for two-dimensional observation.
  • the arm controller 31 receives the information on the convergence angle ⁇ output from the control unit 8a, and the arm controller 31 moves the arm unit 13 in the direction perpendicular to the detection surface 15a based on the information on the convergence angle ⁇ .
  • a control signal is output to obtain a shooting angle ⁇ ′ tilted by 4 °.
  • the arm unit 13 rotates 4 ° according to the control signal output from the arm controller 31.
  • the control unit 8a outputs a control signal to the radiation source controller 32 so as to irradiate an amount of radiation lower than the amount according to the imaging conditions, and reads out a radiation image to the detector controller 33.
  • a control signal is output so that In response to this control signal, the radiation source 17 is irradiated with an amount of radiation that is lower than the amount according to the imaging conditions, and a radiation image obtained by imaging the breast M from the direction at the imaging angle ⁇ ′ of 4 ° is the radiation detector 15. And the radiation image data is read out by the detector controller 33.
  • the image processing unit 8c performs processing for suppressing the granularity of the radiation image by using the read radiation image data as an input. Specifically, a known unsharpening process or a process of lowering the enhancement degree for a known high-frequency component is performed (for details, refer to Japanese Patent Laid-Open Nos. 2003-263635 and 10-105701).
  • the processed radiographic image data is stored in the radiographic image storage unit 8b.
  • the radiographic image data with the imaging angle ⁇ ′ of 4 ° is used only as one image for stereoscopic display.
  • the irradiation when irradiating with an amount of radiation that is lower than the amount according to the imaging conditions, the irradiation may be performed by shortening only the irradiation time without changing the irradiation intensity compared to the normal imaging. It is also possible to reduce the irradiation intensity without changing the irradiation time as compared with the normal shooting, and to irradiate the radiation, or lower the irradiation intensity compared to the normal shooting and the irradiation time. You may make it shorten and perform irradiation.
  • the arm controller 31 outputs a control signal so that the arm unit 13 is in a direction perpendicular to the imaging table 14.
  • a control signal is output so that the shooting angle ⁇ ′ with the arm 13 in the direction perpendicular to the detection surface 15a is 0 °.
  • the arm 13 In response to the control signal output from the arm controller 31, the arm 13 is in a direction perpendicular to the detection surface 15a. Subsequently, the control unit 8a outputs a control signal to the radiation source controller 32 so as to irradiate an amount of radiation corresponding to the imaging conditions, and controls the detector controller 33 to read out a radiation image. Is output. In response to this control signal, an amount of radiation corresponding to the imaging conditions is emitted from the radiation source 17, and a radiation image obtained by imaging the breast M from the direction where the imaging angle ⁇ ′ is 0 ° is detected by the radiation detector 15.
  • the compression plate 18 When imaging is completed, the compression plate 18 is moved to release the compression of the breast M, and the radiation image data is read out by the detector controller 33 and stored in the radiation image storage unit 8b.
  • the image processing unit 8c does not perform the above-described graininess suppression process on the radiation image data obtained by the imaging at the imaging angle ⁇ ′ of 0 °.
  • the processing may be performed with a processing intensity weaker than the granularity suppression processing performed on the radiographic image data obtained by imaging at an imaging angle ⁇ ′ of 4 °.
  • the radiographic image data having an imaging angle ⁇ ′ of 0 ° serves as both an image for two-dimensional observation and one image for stereoscopic display.
  • the afterimage of the radiation detector 15 is reduced.
  • imaging with a low radiation dose and imaging with a high radiation dose are continuously performed, a low radiation dose is obtained. If imaging is performed first, the influence of the afterimage of the radiation detector 15 during subsequent imaging can be suppressed.
  • the graininess suppression process is performed before the radiation image data is stored in the radiation image storage unit 8b.
  • the graininess suppression process is not performed at this timing, and a stereo image is displayed.
  • the graininess suppression process may be performed as one of the predetermined signal processes.
  • the radiographic image data with an imaging angle of 0 ° that serves as both an image for two-dimensional observation and one image for stereoscopic display is maintained only for stereoscopic display while maintaining high image quality.
  • the exposure dose of the patient when acquiring a stereo image can be reduced by reducing the radiation dose to be irradiated.
  • the quality of the stereoscopic display is maintained by the image processing unit 8c performing image processing for suppressing graininess on the radiographic image data obtained by imaging at the imaging angle ⁇ ′ of 4 °.
  • the radiographic image capturing apparatus of the present invention is a mammographic image capturing apparatus.
  • the subject is not limited to the breast, and for example, a radiographic image capturing apparatus that captures the chest, head, or the like is used. Is also possible.

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Abstract

[Problem] To both reduce the amount of radiation to which a patient is exposed and maintain the quality of a stereoscopic display when generating radiological images for the right and left eyes to achieve a stereoscopic view using binocular disparity. [Solution] Provided are: a radiation source (17) capable of sending radiation from two different imaging directions; a radiation detector (15) that detects the sent radiation; a detector controller (33) that reads radiological image signals output from the radiation detector (15) to generate radiological images; a radiation source controller (32) that controls the radiation source (17) such that the amount of radiation sent from the radiation source (17) during imaging in one imaging direction among the two imaging directions is lower than the amount of radiation sent from the radiation source (17) during imaging in the other imaging direction; and an image processing unit (8c) that performs image processing to suppress graininess in the radiological image taken with the lower amount of radiation.

Description

立体視用放射線画像生成装置および方法並びにプログラムStereoscopic radiographic image generation apparatus and method
　本発明は、両眼視差を用いた立体視を行うための左右両目用の放射線画像を生成する技術に関するものである。 The present invention relates to a technique for generating radiographic images for left and right eyes for performing stereoscopic viewing using binocular parallax.
　従来、複数の画像を組み合わせて表示することにより、視差を利用して立体視できることが知られている。このような立体視できる画像（以下、立体視画像またはステレオ画像という）は、同一の被写体を異なる位置から撮影して取得された互いに視差のある複数の画像に基づいて生成される。 Conventionally, it is known that stereoscopic viewing can be performed using parallax by displaying a combination of a plurality of images. Such a stereoscopically viewable image (hereinafter referred to as a stereoscopic image or a stereo image) is generated based on a plurality of images having parallax obtained by photographing the same subject from different positions.
　そして、このような立体視画像の生成は、デジタルカメラやテレビなどの分野だけでなく、放射線画像撮影の分野においても利用されている。すなわち、被検者に対して互いに異なる方向から放射線を照射し、その被検者を透過した放射線を放射線画像検出器によりそれぞれ検出して互いに視差のある複数の放射線画像を取得し、これらの放射線画像に基づいて立体視画像を生成することが行われている。そして、このように立体視画像を生成することによって奥行感のある放射線画像を観察することができ、より診断に適した放射線画像を観察することができる（例えば特許文献１参照）。 And the generation of such stereoscopic images is used not only in the fields of digital cameras and televisions, but also in the field of radiographic imaging. That is, the patient is irradiated with radiation from different directions, the radiation transmitted through the subject is detected by a radiation image detector, and a plurality of radiation images having parallax are obtained, and these radiations are acquired. A stereoscopic image is generated based on the image. By generating a stereoscopic image in this way, a radiographic image having a sense of depth can be observed, and a radiographic image more suitable for diagnosis can be observed (see, for example, Patent Document 1).
　また、読影者が立体視をしやすくするため、放射線画像検出器の検出面に垂直な正対方向からＸ線を照射して得られた放射線画像を利き目に与え、正対方向から所定の角度傾けた斜入方向からＸ線を照射して得られた放射線画像を他方の目に与えるようにすることも提案されている（特許文献２参照）。さらに、このとき、通常のマンモグラフィと同じ撮影方向である正対方向の放射線画像の品質を確保するため、正対方向から撮影する場合の放射線量を斜入方向の場合よりも多くすることも提案されている（特許文献２参照）。 Also, in order to make it easier for the image interpreter to stereoscopically view, a radiographic image obtained by irradiating X-rays from the facing direction perpendicular to the detection surface of the radiation image detector is given to the dominant hand, It has also been proposed to give a radiographic image obtained by irradiating X-rays from an obliquely inclined direction (see Patent Document 2). Furthermore, at this time, in order to ensure the quality of the radiographic image in the facing direction, which is the same imaging direction as normal mammography, it is also proposed to increase the radiation dose when imaging from the facing direction than in the oblique direction. (See Patent Document 2).
特開２０１０－１１０５７１号公報JP 2010-110571 A 特開２０１０－１８７７３５号公報JP 2010-187735 A
　ところで、上記のようなステレオ画像を取得する放射線画像撮影装置では、２次元画像のみ取得する通常の放射線画像撮影装置と比較して、取得する画像の枚数が倍以上に多くなるため、患者の被曝量が増加するという問題がある。 By the way, in the radiographic imaging apparatus which acquires a stereo image as described above, the number of images to be acquired is more than doubled compared to a normal radiographic imaging apparatus that acquires only a two-dimensional image. There is a problem that the amount increases.
　そこで、本出願人は、上記問題を緩和するという観点から、ステレオ画像のうちの一方の画像の撮影時の放射線量を他方の画像よりも低くすることを提案している（米国仮出願61/385,374）。これは、本出願人が見出した、立体視表示の際に左右の画像の画質が一致していなくても立体視表示が可能であるという新たな知見に基づいたものである。 Therefore, from the viewpoint of alleviating the above problem, the present applicant has proposed that the radiation dose at the time of photographing one of the stereo images is lower than that of the other image (US provisional application 61 / 385,374). This is based on the new knowledge found by the present applicant that stereoscopic display is possible even when the image quality of the left and right images does not match during stereoscopic display.
　一方、低線量で撮影された画像は、高線量で撮影された画像よりも画質が低いため、立体視表示が困難になる可能性があり、診断精度の低下が問題となり得る。 On the other hand, an image captured at a low dose has a lower image quality than an image captured at a high dose, so that stereoscopic display may be difficult, and degradation of diagnostic accuracy may be a problem.
　本発明は、上記の事情に鑑みてなされたものであり、患者の被曝量の低減と立体視表示の品質の維持の両立を実現する立体視用放射線画像生成装置および方法並びにプログラムを提供することを目的とする。 The present invention has been made in view of the above circumstances, and provides a stereoscopic radiographic image generation apparatus, method, and program that achieves both reduction in patient exposure and maintenance of stereoscopic display quality. With the goal.
　本発明は、上記新たな知見に関連して見出された、立体視表示の際に左右の画像に対して異なる画像処理を行っても立体視表示が可能であるという知見に基づいたものである。 The present invention is based on the finding that the stereoscopic display is possible even when different image processing is performed on the left and right images in the stereoscopic display, which is found in association with the above-mentioned new knowledge. is there.
　具体的には、本発明の立体視用放射線画像生成装置は、互いに異なる２つの撮影方向から放射線を照射可能な放射線源と、照射された放射線を検出する放射線検出器と、放射線検出器から出力された放射線画像信号を読み取り、その放射線画像信号に基づいて放射線画像を生成する画像生成部と、２つの撮影方向のうちの一方の撮影方向での撮影時に放射線源から照射させる放射線量を、２つの撮影方向のうちの他方の撮影方向での撮影時に放射線源から照射させる放射線量よりも低くするように、放射線源を制御する制御部と、一方の撮影方向での撮影で生成された放射線画像に対して粒状性を抑制する画像処理を行う画像処理部とを設けたことを特徴とする。 Specifically, the stereoscopic radiographic image generation apparatus of the present invention includes a radiation source capable of emitting radiation from two different imaging directions, a radiation detector for detecting the irradiated radiation, and an output from the radiation detector. An image generation unit that reads the radiographic image signal that is generated and generates a radiographic image based on the radiographic image signal, and a radiation dose that is irradiated from a radiation source during imaging in one of the two imaging directions is 2 A radiographic image generated by imaging in one imaging direction and a control unit that controls the radiation source so as to be lower than the radiation dose emitted from the radiation source during imaging in the other imaging direction of the one imaging direction And an image processing unit that performs image processing for suppressing graininess.
　本発明の立体視用放射線画像生成方法は、所定の第１の撮影方向から放射線を照射するステップと、照射された放射線を放射線検出器で検出するステップと、放射線検出器から出力された第１の放射線画像信号を読み取り、その第１の放射線画像信号に基づいて第１の放射線画像を生成するステップと、第１の撮影方向とは異なる第２の撮影方向から放射線を照射するステップと、照射された放射線を放射線検出器で検出するステップと、放射線検出器から出力された第２の放射線画像信号を読み取り、その第２の放射線画像信号に基づいて第２の放射線画像を生成するステップとを有する方法であって、各撮影方向のうちの一方の撮影方向での撮影時に照射させる放射線量が、各撮影方向のうちの他方の撮影方向での撮影時に照射させる放射線量よりも低くなるように、放射線を照射する放射線源を制御するステップと、一方の撮影方向での撮影で生成された放射線画像に対して粒状性を抑制する画像処理を行うステップとをさらに有することを特徴とする。 The stereoscopic radiographic image generation method of the present invention includes a step of irradiating radiation from a predetermined first imaging direction, a step of detecting the irradiated radiation with a radiation detector, and a first output from the radiation detector. Reading the radiation image signal of the first and generating a first radiation image based on the first radiation image signal, irradiating radiation from a second imaging direction different from the first imaging direction, and irradiation Detecting the emitted radiation with a radiation detector, and reading a second radiation image signal output from the radiation detector and generating a second radiation image based on the second radiation image signal. The amount of radiation to be irradiated at the time of photographing in one of the photographing directions is irradiated at the time of photographing in the other of the photographing directions. A step of controlling a radiation source that emits radiation so as to be lower than a radiation dose, and a step of performing image processing for suppressing graininess on a radiation image generated by imaging in one imaging direction It is characterized by having.
　本発明の立体視用放射線画像生成プログラムは、互いに異なる２つの撮影方向から放射線を照射可能な放射線源と、照射された放射線を検出する放射線検出器と、放射線検出器から出力された放射線画像信号を読み取り、その放射線画像信号に基づいて放射線画像を生成する画像生成部とを備えた立体視用放射線画像生成装置に、各撮影方向のうちの一方の撮影方向での撮影時に照射させる放射線量が、各撮影方向のうちの他方の撮影方向での撮影時に照射させる放射線量よりも低くなるように、放射線を照射する放射線源を制御するステップと、一方の撮影方向での撮影で生成された放射線画像に対して粒状性を抑制する画像処理を行うステップとを実行させることを特徴とする。 The stereoscopic radiographic image generation program of the present invention includes a radiation source capable of irradiating radiation from two different imaging directions, a radiation detector for detecting the irradiated radiation, and a radiation image signal output from the radiation detector. The amount of radiation to be irradiated at the time of imaging in one of the imaging directions to a stereoscopic radiographic image generation apparatus including an image generation unit that generates a radiographic image based on the radiographic image signal , A step of controlling a radiation source for irradiating radiation so as to be lower than a radiation dose to be irradiated at the time of imaging in the other imaging direction of each imaging direction, and radiation generated by imaging in one imaging direction A step of performing image processing for suppressing graininess on the image.
　ここで、「粒状性を抑制する画像処理」の具体例としては、非鮮鋭化処理や、高周波成分の強調度を下げる処理が挙げられる。 Here, specific examples of “image processing for suppressing graininess” include unsharpening processing and processing for reducing the enhancement degree of high-frequency components.
　また、この粒状性を抑制する画像処理を、各撮影方向で得られた放射線画像の両方に対して、異なる処理強度で行うようにしてもよい。この場合、上記一方（放射線量が低い方）の撮影方向で得られた放射線画像に対して、上記他方（放射線量が高い方）の撮影方向で得られた放射線画像よりも強い処理強度で粒状性を抑制する画像処理を行うようにすることが好ましい。 Further, the image processing for suppressing the graininess may be performed with different processing intensities for both of the radiographic images obtained in the respective photographing directions. In this case, with respect to the radiographic image obtained in the one (lower radiation dose) imaging direction, the granularity is stronger than the radiographic image obtained in the other (higher radiation dose) imaging direction. It is preferable to perform image processing to suppress the property.
　本発明において、上記２つの撮影方向のうちの他方（放射線量が高い方）の撮影方向と放射線検出器の検出面に直交する方向とのなす角度が、上記２つの撮影方向のうちの一方（放射線量が低い方）の撮影方向と直交する方向とのなす角度よりも小さくすることが好ましい。このとき、上記他方の撮影方向（放射線量が高い方）と放射線検出器の検出面に直交する方向とのなす角度は、０°とすることが好ましい。 In the present invention, the angle formed by the imaging direction of the other of the two imaging directions (the one with the higher radiation dose) and the direction orthogonal to the detection surface of the radiation detector is one of the two imaging directions ( It is preferable to make it smaller than the angle formed by the direction perpendicular to the imaging direction of the lower radiation dose). At this time, it is preferable that the angle formed by the other imaging direction (the one with the higher radiation dose) and the direction perpendicular to the detection surface of the radiation detector is 0 °.
　本発明によれば、互いに異なる２つの撮影方向において放射線源から放射線を照射して撮影を行なう際に、２つの撮影方向のうちの一方の撮影時に放射線源から照射させる放射線量を、２つの撮影方向のうちの他方の撮影時に放射線源から照射させる放射線量よりも低くするようにしたので、ステレオ画像を取得する際の患者の被曝量を低減させることができるとともに、一方の撮影方向での撮影で生成された放射線画像に対して粒状性を抑制する画像処理を行うことにより、ステレオ画像を用いた立体視表示の品質も維持される。 According to the present invention, when imaging is performed by irradiating radiation from a radiation source in two different imaging directions, the radiation dose to be irradiated from the radiation source during one imaging in the two imaging directions Since the radiation dose emitted from the radiation source during imaging in the other of the directions is set lower, the exposure dose of the patient when acquiring a stereo image can be reduced, and imaging in one imaging direction can be performed. The quality of stereoscopic display using a stereo image is also maintained by performing image processing that suppresses graininess on the radiation image generated in step (b).
本発明の放射線画像撮影表示システムの一実施の形態を用いたステレオ乳房画像撮影表示システムの概略構成図Schematic configuration diagram of a stereo breast image radiographing display system using an embodiment of a radiographic image radiographing display system of the present invention 図１に示すステレオ乳房画像撮影表示システムのアーム部を図１の右方向から見た図The figure which looked at the arm part of the stereo breast image radiographing display system shown in FIG. 1 from the right direction of FIG. 図１に示すステレオ乳房画像撮影表示システムのコンピュータ内部の概略構成を示すブロック図The block diagram which shows schematic structure inside the computer of the stereo breast image radiographing display system shown in FIG.
　以下、図面を参照して本発明の放射線画像撮影装置の一実施の形態を用いたステレオ乳房画像撮影表示システムについて説明する。まず、本実施の形態の乳房画像撮影表示システム全体の概略構成について説明する。図１は乳房画像撮影表示システムの概略構成を示す図、図２は図１に示すステレオ乳房画像撮影表示システムのアーム部を図１の右方向から見た図、図３は図１に示すステレオ乳房画像撮影表示システムのコンピュータ内部の概略構成を示すブロック図である。 Hereinafter, a stereo breast image radiographing display system using an embodiment of the radiographic image radiographing apparatus of the present invention will be described with reference to the drawings. First, a schematic configuration of the entire breast image capturing and displaying system according to the present embodiment will be described. 1 is a diagram showing a schematic configuration of a breast image radiographing display system, FIG. 2 is a diagram of an arm portion of the stereo mammography radiographing display system shown in FIG. 1, viewed from the right side in FIG. 1, and FIG. It is a block diagram which shows schematic structure inside the computer of a breast image radiography display system.
　本実施形態の乳房画像撮影表示システム１は、図１に示すように、乳房画像撮影装置１０と、乳房画像撮影装置１０に接続されたコンピュータ８と、コンピュータ８に接続されたモニタ９および入力部７とを備えている。 As shown in FIG. 1, a breast image radiographing display system 1 of the present embodiment includes a mammography apparatus 10, a computer 8 connected to the mammography apparatus 10, a monitor 9 connected to the computer 8, and an input unit. 7.
　そして、乳房画像撮影装置１０は、図１に示すように、基台１１と、基台１１に対し上下方向（Ｚ方向）に移動可能であり、かつ回転可能な回転軸１２と、回転軸１２により基台１１と連結されたアーム部１３を備えている。なお、図２には、図１の右方向から見たアーム部１３を示している。 As shown in FIG. 1, the mammography apparatus 10 includes a base 11, a rotary shaft 12 that can move in the vertical direction (Z direction) with respect to the base 11, and can rotate. The arm part 13 connected with the base 11 is provided. FIG. 2 shows the arm 13 viewed from the right direction in FIG.
　アーム部１３はアルファベットのＣの形をしており、その一端には撮影台１４が、その他端には撮影台１４と対向するように放射線照射部１６が取り付けられている。アーム部１３の回転および上下方向の移動は、基台１１に組み込まれたアームコントローラ３１により制御される。 The arm section 13 has an alphabet C shape, and a radiation table 16 is attached to one end of the arm section 13 so as to face the imaging table 14 at the other end. The rotation and vertical movement of the arm unit 13 are controlled by an arm controller 31 incorporated in the base 11.
　撮影台１４の内部には、フラットパネルディテクタ等の放射線画像検出器１５（放射線検出器に相当する）と、放射線画像検出器１５からの電荷信号の読み出しを制御する検出器コントローラ３３が備えられている。また、撮影台１４の内部には、放射線画像検出器１５から読み出された電荷信号を電圧信号に変換するチャージアンプや、チャージアンプから出力された電圧信号をサンプリングする相関２重サンプリング回路や、電圧信号をデジタル信号に変換するＡＤ変換部などが設けられた回路基板なども設置されている。なお、上述した検出器コントローラ３３や回路基板と、コンピュータ８によって画像生成手段が構成される。 Inside the imaging table 14, a radiation image detector 15 (corresponding to a radiation detector) such as a flat panel detector and a detector controller 33 that controls reading of a charge signal from the radiation image detector 15 are provided. Yes. Further, inside the imaging table 14, a charge amplifier that converts the charge signal read from the radiation image detector 15 into a voltage signal, a correlated double sampling circuit that samples the voltage signal output from the charge amplifier, A circuit board provided with an AD conversion unit for converting a voltage signal into a digital signal is also installed. The detector controller 33 and the circuit board described above and the computer 8 constitute an image generating means.
　また、撮影台１４はアーム部１３に対し回転可能に構成されており、基台１１に対してアーム部１３が回転したときでも、撮影台１４の向きは基台１１に対し固定された向きとすることができる。 In addition, the photographing table 14 is configured to be rotatable with respect to the arm unit 13, and even when the arm unit 13 rotates with respect to the base 11, the direction of the photographing table 14 is fixed to the base 11. can do.
　放射線画像検出器１５は、放射線画像の記録と読出しを繰り返して行うことができるものであり、放射線の照射を直接受けて電荷を発生する、いわゆる直接変換型の放射線画像検出器を用いてもよいし、放射線を一旦可視光に変換し、その可視光を電荷信号に変換する、いわゆる間接変換型の放射線画像検出器を用いるようにしてもよい。また、放射線画像信号の読出方式としては、ＴＦＴ（thin film transistor）スイッチをオン・オフされることによって放射線画像信号が読みだされる、いわゆるＴＦＴ読出方式のものや、読取光を照射することによって放射線画像信号が読み出される、いわゆる光読出方式のものを用いることが望ましいが、これに限らずその他のものを用いるようにしてもよい。放射線画像検出器１５から出力された放射線画像信号はＡＤ変換されて放射線画像データとされる。 The radiographic image detector 15 can repeatedly perform recording and reading of radiographic images, and a so-called direct conversion type radiographic image detector that directly receives radiation and generates charges may be used. A so-called indirect conversion type radiation image detector that converts radiation once into visible light and converts the visible light into a charge signal may be used. As a radiation image signal readout method, a radiation image signal is read out by turning on / off a TFT (thin film transistor) switch, or by irradiating reading light. It is desirable to use a so-called optical readout system from which a radiation image signal is read out, but the present invention is not limited to this, and other systems may be used. The radiographic image signal output from the radiographic image detector 15 is AD-converted into radiographic image data.
　放射線照射部１６の中には放射線源１７と、放射線源コントローラ３２が収納されている。放射線源コントローラ３２は、放射線源１７から放射線を照射するタイミングと、放射線源１７における放射線発生条件（管電圧、管電流、時間、管電流時間積等）を制御するものである。 A radiation source 17 and a radiation source controller 32 are accommodated in the radiation irradiation unit 16. The radiation source controller 32 controls the timing of irradiating radiation from the radiation source 17 and the radiation generation conditions (tube voltage, tube current, time, tube current time product, etc.) in the radiation source 17.
　また、アーム部１３の中央部には、撮影台１４の上方に配置されて乳房Ｍを押さえつけて圧迫する圧迫板１８と、その圧迫板１８を支持する支持部２０と、支持部２０を上下方向（Ｚ方向）に移動させる移動機構１９が設けられている。圧迫板１８の位置、圧迫圧は、圧迫板コントローラ３４により制御される。 Further, in the central portion of the arm portion 13, a compression plate 18 that is disposed above the imaging table 14 and presses and compresses the breast M, a support portion 20 that supports the compression plate 18, and a support portion 20 that extends in the vertical direction. A moving mechanism 19 for moving in the (Z direction) is provided. The position of the compression plate 18 and the compression pressure are controlled by the compression plate controller 34.
　コンピュータ８は、中央処理装置（ＣＰＵ）および半導体メモリやハードディスクやＳＳＤ等のストレージデバイスなどを備えており、これらのハードウェアによって、図３に示すような制御部８ａ、放射線画像記憶部８ｂおよび画像処理部８ｃが構成されている。 The computer 8 includes a central processing unit (CPU) and a storage device such as a semiconductor memory, a hard disk, and an SSD. The control unit 8a, the radiation image storage unit 8b, and the image shown in FIG. A processing unit 8c is configured.
　制御部８ａは、各種のコントローラ３１～３４に対して所定の制御信号を出力し、システム全体の制御を行うものである。具体的な制御方法については後で詳述する。放射線画像記憶部８ｂは、放射線画像検出器１５によって取得された撮影角度毎の放射線画像データを記憶するものである。画像処理部８ｃは、放射線画像データに対して種々の画像処理を施すためのものである。本発明の粒状性を抑制する処理も、この画像処理部８ｃで行われる。 The controller 8a outputs predetermined control signals to the various controllers 31 to 34 to control the entire system. A specific control method will be described in detail later. The radiation image storage unit 8b stores radiation image data for each imaging angle acquired by the radiation image detector 15. The image processing unit 8c is for performing various image processing on the radiation image data. The processing for suppressing graininess according to the present invention is also performed by the image processing unit 8c.
　入力部７は、たとえば、キーボードやマウスなどのポインティングデバイスから構成されるものであり、撮影者による撮影条件などの入力や操作指示の入力なども受け付けるものである。 The input unit 7 is composed of a pointing device such as a keyboard and a mouse, for example, and accepts input of shooting conditions and operation instructions by the photographer.
　モニタ９は、コンピュータ８から出力された２つの放射線画像データを用いて、撮影方向毎の放射線画像をそれぞれ２次元画像として表示することにより、ステレオ画像を表示するように構成されたものである。 The monitor 9 is configured to display a stereo image by using the two radiographic image data output from the computer 8 to display the radiographic image for each imaging direction as a two-dimensional image.
　ステレオ画像を表示する構成としては、たとえば、２つの画面を用いて２つの放射線画像データに基づく放射線画像をそれぞれ表示させて、これらをハーフミラーや偏光グラスなどを用いることで一方の放射線画像は観察者の右目に入射させ、他方の放射線画像は観察者の左目に入射させることによってステレオ画像を表示する構成を採用することができる。 As a configuration for displaying a stereo image, for example, radiographic images based on two radiographic image data are displayed using two screens, and one of the radiographic images is observed by using a half mirror, a polarizing glass, or the like. It is possible to adopt a configuration in which a stereo image is displayed by being incident on the right eye of the observer and the other radiation image is incident on the left eye of the observer.
　または、たとえば、２つの放射線画像を所定の視差量だけずらして重ね合わせて表示し、これを偏光グラスで観察することでステレオ画像を生成する構成としてもよいし、もしくはパララックスバリア方式およびレンチキュラー方式のように、２つの放射線画像を立体視可能な３Ｄ液晶に表示することによってステレオ画像を生成する構成としてもよい。 Or, for example, two radiographic images may be displayed in a superimposed manner while being shifted by a predetermined amount of parallax, and this may be configured to generate a stereo image by observing with a polarizing glass, or a parallax barrier method and a lenticular method As described above, a stereo image may be generated by displaying two radiation images on a stereoscopically viewable 3D liquid crystal.
　また、ステレオ画像を表示する装置と２次元画像を表示する装置とは別個に構成するようにしてもよいし、同じ画面上で表示できる場合には同じ装置として構成するようにしてもよい。 Further, the device that displays a stereo image and the device that displays a two-dimensional image may be configured separately, or may be configured as the same device if they can be displayed on the same screen.
　次に、本実施形態の乳房画像撮影表示システムの作用について説明する。
　最初に撮影台１４の上に乳房Ｍが設置され、圧迫板１８により乳房Ｍが所定の圧力によって圧迫される。
　次に、入力部７おいて、２つの異なる撮影方向がなす角度（以下、輻輳角θという）および輻輳角θを構成する撮影角度θ'の組み合わせを含む種々の撮影条件が入力された後、撮影開始の指示が入力される。 Next, the operation of the mammography / display system of the present embodiment will be described.
First, the breast M is set on the imaging table 14, and the breast M is compressed with a predetermined pressure by the compression plate 18.
Next, after various imaging conditions including a combination of an angle formed by two different imaging directions (hereinafter referred to as a convergence angle θ) and an imaging angle θ ′ constituting the convergence angle θ are input in the input unit 7, An instruction to start shooting is input.
　そして、入力部７において撮影開始の指示があると、乳房Ｍのステレオ画像の撮影が行われる。具体的には、まず、制御部８ａが、輻輳角θと輻輳角θを構成する撮影角度θ'の情報をアームコントローラ３１に出力する。なお、本実施の形態においては、撮影枚数を減らすべく２次元観察用の画像と立体視表示するための一方の画像とを兼ねるようにするため、このときの輻輳角θの情報としてθ＝４°、輻輳角θを構成する撮影角度θ’の組み合わせとしてθ’＝０°とθ’＝４°の組み合わせが設定されているものとするが、これに限られるものではなく、撮影者は入力部７において任意の輻輳角θを設定可能である。なお、輻輳角θは小さすぎても大きすぎても適切な立体視を行なわせることが難しくなるため、４°以上１５°以下に設定されることが望ましい。また、撮影角度θ’の組み合わせについても、一方の撮影角度θ’が他方の撮影角度θ’よりも小さいものである限り、特に限定されるものではない。なお、撮影角度θ’の組み合わせとしては、上記の一方の撮影角度θ’、すなわち２次元観察用の画像を撮影するための撮影角度θ’は０°とすることが望ましい。これは、放射線画像検出器１５の正面から撮影した画像が、最も２次元観察に適しているからである。 Then, when there is an instruction to start photographing at the input unit 7, a stereo image of the breast M is photographed. Specifically, first, the control unit 8 a outputs information about the convergence angle θ and the imaging angle θ ′ constituting the convergence angle θ to the arm controller 31. In the present embodiment, in order to reduce the number of images to be taken, the image for two-dimensional observation and one image for stereoscopic display are combined, so that information on the convergence angle θ at this time is θ = 4. Assuming that the combination of θ ′ = 0 ° and θ ′ = 4 ° is set as the combination of the shooting angles θ ′ constituting the convergence angle θ, this is not restrictive, and the photographer inputs The unit 7 can set an arbitrary convergence angle θ. Note that the convergence angle θ is preferably set to 4 ° or more and 15 ° or less because it is difficult to perform appropriate stereoscopic viewing if the convergence angle θ is too small or too large. Further, the combination of the shooting angles θ ′ is not particularly limited as long as one shooting angle θ ′ is smaller than the other shooting angle θ ′. As a combination of the shooting angle θ ′, the one shooting angle θ ′ described above, that is, the shooting angle θ ′ for shooting an image for two-dimensional observation is preferably 0 °. This is because an image taken from the front of the radiation image detector 15 is most suitable for two-dimensional observation.
　アームコントローラ３１において、制御部８ａから出力された輻輳角θの情報が受け付けられ、アームコントローラ３１は、この輻輳角θの情報に基づいて、アーム部１３を検出面１５ａに垂直な方向に対して４°傾く撮影角度θ'となる制御信号を出力する。 The arm controller 31 receives the information on the convergence angle θ output from the control unit 8a, and the arm controller 31 moves the arm unit 13 in the direction perpendicular to the detection surface 15a based on the information on the convergence angle θ. A control signal is output to obtain a shooting angle θ ′ tilted by 4 °.
　アームコントローラ３１から出力された制御信号に応じてアーム部１３が４°回転する。続いて制御部８ａは、放射線源コントローラ３２に対して撮影条件に応じた量よりも低くした量の放射線の照射を行うよう制御信号を出力するとともに、検出器コントローラ３３に対して放射線画像の読出しを行うよう制御信号を出力する。この制御信号に応じて、放射線源１７から撮影条件に応じた量よりも低くした量の放射線が照射され、乳房Ｍを撮影角度θ'が４°の方向から撮影した放射線画像が放射線検出器１５によって検出され、検出器コントローラ３３によって放射線画像データが読み出される。 The arm unit 13 rotates 4 ° according to the control signal output from the arm controller 31. Subsequently, the control unit 8a outputs a control signal to the radiation source controller 32 so as to irradiate an amount of radiation lower than the amount according to the imaging conditions, and reads out a radiation image to the detector controller 33. A control signal is output so that In response to this control signal, the radiation source 17 is irradiated with an amount of radiation that is lower than the amount according to the imaging conditions, and a radiation image obtained by imaging the breast M from the direction at the imaging angle θ ′ of 4 ° is the radiation detector 15. And the radiation image data is read out by the detector controller 33.
　そして、画像処理部８ｃが、読み出された放射線画像データを入力として、放射線画像の粒状度を抑制する処理を行う。具体的には、公知の非鮮鋭化処理、あるいは、公知の高周波成分に対する強調度を下げる処理を行う（詳細は、特開2003-263635号公報、特開平10-105701号公報等参照）。処理済みの放射線画像データは、放射線画像記憶部８ｂに記憶される。なお、撮影角度θ'が４°の放射線画像データは、立体視表示するための一方の画像としてのみに用いられるものとなる。 Then, the image processing unit 8c performs processing for suppressing the granularity of the radiation image by using the read radiation image data as an input. Specifically, a known unsharpening process or a process of lowering the enhancement degree for a known high-frequency component is performed (for details, refer to Japanese Patent Laid-Open Nos. 2003-263635 and 10-105701). The processed radiographic image data is stored in the radiographic image storage unit 8b. The radiographic image data with the imaging angle θ ′ of 4 ° is used only as one image for stereoscopic display.
　なお、撮影条件に応じた量よりも低くした量の放射線の照射を行う場合は、通常撮影時と比較して照射強度を変えずに照射時間のみ短くして放射線の照射を行うようにしてもよいし、通常撮影時と比較して照射時間を変えずに照射強度のみ弱くして放射線の照射を行うようにしてもよいし、通常撮影時と比較して照射強度を弱くするとともに照射時間も短くして放射線の照射を行うようにしてもよい。 In addition, when irradiating with an amount of radiation that is lower than the amount according to the imaging conditions, the irradiation may be performed by shortening only the irradiation time without changing the irradiation intensity compared to the normal imaging. It is also possible to reduce the irradiation intensity without changing the irradiation time as compared with the normal shooting, and to irradiate the radiation, or lower the irradiation intensity compared to the normal shooting and the irradiation time. You may make it shorten and perform irradiation.
　続いて、アームコントローラ３１は、アーム部１３が撮影台１４に垂直な方向となるよう制御信号を出力する。すなわち、本実施形態においては、アーム部１３を検出面１５ａに垂直な方向とする撮影角度θ'が０°となる制御信号を出力する。 Subsequently, the arm controller 31 outputs a control signal so that the arm unit 13 is in a direction perpendicular to the imaging table 14. In other words, in the present embodiment, a control signal is output so that the shooting angle θ ′ with the arm 13 in the direction perpendicular to the detection surface 15a is 0 °.
　アームコントローラ３１から出力された制御信号に応じてアーム部１３が検出面１５ａに対して垂直な方向となる。続いて制御部８ａは、放射線源コントローラ３２に対して撮影条件に応じた量の放射線の照射を行うよう制御信号を出力するとともに、検出器コントローラ３３に対して放射線画像の読出しを行うよう制御信号を出力する。この制御信号に応じて、放射線源１７から撮影条件に応じた量の放射線が照射され、乳房Ｍを撮影角度θ'が０°の方向から撮影した放射線画像が放射線検出器１５によって検出される。撮影が終了すると圧迫板１８を移動させて乳房Ｍの圧迫を解除するとともに、検出器コントローラ３３によって放射線画像データが読み出され、放射線画像記憶部８ｂに記憶される。ここで、この撮影角度θ'が０°での撮影で得られた放射線画像データに対しては、画像処理部８ｃは上記の粒状性抑制処理を行わない。あるいは、撮影角度θ'が４°での撮影で得られた放射線画像データに対して行った粒状性抑制処理よりも弱い処理強度で処理を行うようにしてもよい。なお、撮影角度θ'が０°の放射線画像データは、２次元観察用の画像と立体視表示するための一方の画像とを兼ねるものとなる。 In response to the control signal output from the arm controller 31, the arm 13 is in a direction perpendicular to the detection surface 15a. Subsequently, the control unit 8a outputs a control signal to the radiation source controller 32 so as to irradiate an amount of radiation corresponding to the imaging conditions, and controls the detector controller 33 to read out a radiation image. Is output. In response to this control signal, an amount of radiation corresponding to the imaging conditions is emitted from the radiation source 17, and a radiation image obtained by imaging the breast M from the direction where the imaging angle θ ′ is 0 ° is detected by the radiation detector 15. When imaging is completed, the compression plate 18 is moved to release the compression of the breast M, and the radiation image data is read out by the detector controller 33 and stored in the radiation image storage unit 8b. Here, the image processing unit 8c does not perform the above-described graininess suppression process on the radiation image data obtained by the imaging at the imaging angle θ ′ of 0 °. Alternatively, the processing may be performed with a processing intensity weaker than the granularity suppression processing performed on the radiographic image data obtained by imaging at an imaging angle θ ′ of 4 °. Note that the radiographic image data having an imaging angle θ ′ of 0 ° serves as both an image for two-dimensional observation and one image for stereoscopic display.
　低い放射線量で撮影を行なった場合には放射線検出器１５の残像が少なくなるため、このように、低い放射線量での撮影および高い放射線量での撮影を連続的に行なう場合に、低い放射線量での撮影を先に行なうようにすれば、後の撮影時における放射線検出器１５の残像の影響を抑えることができる。 When imaging is performed with a low radiation dose, the afterimage of the radiation detector 15 is reduced. Thus, when imaging with a low radiation dose and imaging with a high radiation dose are continuously performed, a low radiation dose is obtained. If imaging is performed first, the influence of the afterimage of the radiation detector 15 during subsequent imaging can be suppressed.
　そして、ユーザーからステレオ画像表示が要求された際には、コンピュータ８の放射線画像記憶部８ｂに記憶された２つの放射線画像データが放射線画像記憶部８ｂから読み出された後、所定の信号処理が施されてモニタ９に出力され、モニタ９において、乳房Ｍのステレオ画像が表示される。なお、本実施形態では、放射線画像データが放射線画像記憶部８ｂに記憶される前に粒状性抑制処理を行うようにしたが、このタイミングで粒状性抑制処理を行わずに、ステレオ画像表示の際に、上記所定の信号処理の１つとして粒状性抑制処理を行うようにしてもよい。 When a stereo image display is requested by the user, after two pieces of radiographic image data stored in the radiographic image storage unit 8b of the computer 8 are read from the radiographic image storage unit 8b, predetermined signal processing is performed. Applied to the monitor 9 and a stereo image of the breast M is displayed on the monitor 9. In the present embodiment, the graininess suppression process is performed before the radiation image data is stored in the radiation image storage unit 8b. However, the graininess suppression process is not performed at this timing, and a stereo image is displayed. In addition, the graininess suppression process may be performed as one of the predetermined signal processes.
　また、ユーザーから２次元画像表示が要求された際には、コンピュータ８の放射線画像記憶部８ｂに記憶された２つの放射線画像データのうち撮影角度θ'が０°の放射線画像データが放射線画像記憶部８ｂから読み出された後、所定の信号処理が施されてモニタ９に出力され、モニタ９において、乳房Ｍの２次元画像が表示される。 When a two-dimensional image display is requested by the user, radiation image data with an imaging angle θ ′ of 0 ° is stored in the radiation image among the two radiation image data stored in the radiation image storage unit 8b of the computer 8. After being read from the unit 8 b, predetermined signal processing is performed and output to the monitor 9, and a two-dimensional image of the breast M is displayed on the monitor 9.
　このような構成とすることにより、２次元観察用の画像と立体視表示するための一方の画像とを兼ねる撮影角度０°の放射線画像データについては高画質を維持しつつ、立体視表示のみに用いる放射線画像データについては照射する放射線量を低くした分、ステレオ画像を取得する際の患者の被曝量を低減させることができる。一方、画像処理部８ｃが、撮影角度θ'が４°での撮影で得られた放射線画像データに対して粒状性を抑制する画像処理を行うことにより、立体視表示の品質も維持される。 By adopting such a configuration, the radiographic image data with an imaging angle of 0 ° that serves as both an image for two-dimensional observation and one image for stereoscopic display is maintained only for stereoscopic display while maintaining high image quality. With respect to the radiation image data to be used, the exposure dose of the patient when acquiring a stereo image can be reduced by reducing the radiation dose to be irradiated. On the other hand, the quality of the stereoscopic display is maintained by the image processing unit 8c performing image processing for suppressing graininess on the radiographic image data obtained by imaging at the imaging angle θ ′ of 4 °.
　なお、上記実施の形態においては、本発明の放射線画像撮影装置を乳房画像撮影装置としているが、被検体としては乳房に限らず、たとえば胸部や頭部等を撮影する放射線画像撮影装置を用いることも可能である。 In the above embodiment, the radiographic image capturing apparatus of the present invention is a mammographic image capturing apparatus. However, the subject is not limited to the breast, and for example, a radiographic image capturing apparatus that captures the chest, head, or the like is used. Is also possible.

Claims (7)

  1. 　互いに異なる２つの撮影方向から放射線を照射可能な放射線源と、
    　前記照射された放射線を検出する放射線検出器と、
    　該放射線検出器から出力された放射線画像信号を読み取り、該放射線画像信号に基づいて放射線画像を生成する画像生成部と、
    　前記２つの撮影方向のうちの一方の撮影方向での撮影時に前記放射線源から照射させる放射線量を、前記２つの撮影方向のうちの他方の撮影方向での撮影時に前記放射線源から照射させる放射線量よりも低くするように、前記放射線源を制御する制御部と、
    　前記一方の撮影方向での撮影で生成された放射線画像に対して粒状性を抑制する画像処理を行う画像処理部とを備えたことを特徴とする立体視用放射線画像生成装置。     A radiation source capable of emitting radiation from two different imaging directions;
    A radiation detector for detecting the irradiated radiation;
    An image generation unit that reads a radiation image signal output from the radiation detector and generates a radiation image based on the radiation image signal;
    The amount of radiation irradiated from the radiation source during imaging in one of the two imaging directions is the amount of radiation irradiated from the radiation source during imaging in the other imaging direction of the two imaging directions. A control unit for controlling the radiation source so as to be lower than
    A stereoscopic radiographic image generation apparatus, comprising: an image processing unit that performs image processing for suppressing graininess on a radiographic image generated by imaging in the one imaging direction.
  2. 　前記画像処理が、非鮮鋭化処理であることを特徴とする請求項１記載の立体視用放射線画像生成装置。 The radiological image generation apparatus for stereoscopic vision according to claim 1, wherein the image processing is unsharpening processing.
  3. 　前記画像処理が、前記一方の撮影方向での撮影で生成された放射線画像の高周波成分の強調度を下げる処理であることを特徴とする請求項１記載の立体視用放射線画像生成装置。 2. The stereoscopic radiographic image generation apparatus according to claim 1, wherein the image processing is a process of reducing the enhancement degree of a high-frequency component of a radiographic image generated by imaging in the one imaging direction.
  4. 　前記他方の撮影方向と前記放射線検出器の検出面に直交する方向とのなす角度が、前記一方の撮影方向と前記直交する方向とのなす角度よりも小さいことを特徴とする請求項１から３のいずれか１項記載の立体視用放射線画像生成装置。 The angle formed between the other imaging direction and the direction orthogonal to the detection surface of the radiation detector is smaller than the angle formed between the one imaging direction and the orthogonal direction. The radiographic image generation apparatus for stereoscopic vision according to any one of the above.
  5. 　前記他方の撮影方向と前記放射線検出器の検出面に直交する方向とのなす角度が０°であることを特徴とする請求項４記載の立体視用放射線画像生成装置。 5. The stereoscopic radiographic image generation apparatus according to claim 4, wherein an angle formed between the other imaging direction and a direction orthogonal to a detection surface of the radiation detector is 0 °.
  6. 　所定の第１の撮影方向から放射線を照射するステップと、
    　前記照射された放射線を放射線検出器で検出するステップと、
    　該放射線検出器から出力された第１の放射線画像信号を読み取り、該第１の放射線画像信号に基づいて第１の放射線画像を生成するステップと、
    　前記第１の撮影方向とは異なる第２の撮影方向から放射線を照射するステップと、
    　前記照射された放射線を放射線検出器で検出するステップと、
    　該放射線検出器から出力された第２の放射線画像信号を読み取り、該第２の放射線画像信号に基づいて第２の放射線画像を生成するステップとを有する立体視用放射線画像生成方法であって、
    　前記各撮影方向のうちの一方の撮影方向での撮影時に照射させる放射線量が、前記各撮影方向のうちの他方の撮影方向での撮影時に照射させる放射線量よりも低くなるように、放射線を照射する放射線源を制御するステップと、
    　前記一方の撮影方向での撮影で生成された放射線画像に対して粒状性を抑制する画像処理を行うステップとをさらに有することを特徴とする立体視用放射線画像生成方法。     Irradiating radiation from a predetermined first imaging direction;
    Detecting the irradiated radiation with a radiation detector;
    Reading a first radiographic image signal output from the radiation detector and generating a first radiographic image based on the first radiographic image signal;
    Irradiating radiation from a second imaging direction different from the first imaging direction;
    Detecting the irradiated radiation with a radiation detector;
    A radiographic image generation method for stereoscopic vision, comprising: reading a second radiographic image signal output from the radiation detector, and generating a second radiographic image based on the second radiographic image signal,
    Irradiation is performed such that the radiation dose to be irradiated at the time of imaging in one of the imaging directions is lower than the radiation dose to be irradiated at the time of imaging in the other imaging direction of the imaging directions. Controlling the radiation source to be
    And a step of performing image processing for suppressing graininess on a radiographic image generated by imaging in the one imaging direction.
  7. 　互いに異なる２つの撮影方向から放射線を照射可能な放射線源と、前記照射された放射線を検出する放射線検出器と、該放射線検出器から出力された放射線画像信号を読み取り、該放射線画像信号に基づいて放射線画像を生成する画像生成部とを備えた立体視用放射線画像生成装置に、
    　前記各撮影方向のうちの一方の撮影方向での撮影時に照射させる放射線量が、前記各撮影方向のうちの他方の撮影方向での撮影時に照射させる放射線量よりも低くなるように、放射線を照射する放射線源を制御するステップと、
    　前記一方の撮影方向での撮影で生成された放射線画像に対して粒状性を抑制する画像処理を行うステップとを実行させることを特徴とする立体視用放射線画像生成プログラム。
     
          A radiation source capable of emitting radiation from two different imaging directions, a radiation detector for detecting the irradiated radiation, a radiation image signal output from the radiation detector, and reading the radiation image signal based on the radiation image signal A stereoscopic radiographic image generation apparatus including an image generation unit that generates a radiographic image,
    Irradiation is performed such that the radiation dose to be irradiated at the time of imaging in one of the imaging directions is lower than the radiation dose to be irradiated at the time of imaging in the other imaging direction of the imaging directions. Controlling the radiation source to be
    And a step of performing image processing for suppressing graininess on a radiographic image generated by imaging in the one imaging direction.

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