JP2012175995A - Radiographic imaging method, and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To acquire radiographic images allowing reduction of a blink that occurs upon 3D viewing while leaving information useful in medical image diagnosis, in a radiation image acquisition method and device acquiring a plurality of radiation images constituting a stereoscopic image.SOLUTION: Per-direction radiographic images detected by irradiating radiation to a subject from two imaging directions different from each other is acquired, and blurring processing is applied to an area present in only one acquired radiation image and absent in the other radiation image.

Description

  The present invention relates to a radiographic image acquisition method and apparatus for acquiring radiographic images for each imaging direction detected by irradiating a subject with radiation from two different imaging directions.

  Conventionally, it is known that stereoscopic viewing can be performed using parallax by displaying a plurality of images in combination. 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 directions.

  Such generation of 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. And by generating a stereoscopic image in this way, a radiographic image with a sense of depth can be observed, and a radiographic image more suitable for diagnosis can be observed.

  Here, as described above, the plurality of radiographic images constituting the stereoscopic image are obtained by imaging the subject from different imaging directions, and thus are areas that exist only in one radiographic image. The region that does not exist in the other radiographic image exists at the end of each radiographic image.

  When such a region exists at the end of each radiographic image, only one two-dimensional image is displayed for this region portion, so that it cannot be stereoscopically viewed, and the entire radiographic image is stereoscopically viewed. It is observed as flickering and becomes very uncomfortable for the observer, and it becomes a burden of stereoscopic vision.

  Therefore, in Patent Document 1, for example, a region that exists only in one radiographic image but that does not exist in the other radiographic image is subjected to mask processing or the like, thereby deleting information in this region. Has been proposed.

JP 2010-103866 A

  However, unlike the image of the digital camera disclosed in Patent Document 1, the radiographic image includes information effective for medical image diagnosis even in an area that exists only in one image. There is a possibility that proper medical image diagnosis cannot be performed if this is completely deleted.

  In view of the above circumstances, the present invention provides a radiographic image acquisition method and apparatus for acquiring radiographic images for each imaging direction detected by irradiating a subject with radiation from two different imaging directions. It is an object of the present invention to provide a radiological image acquisition method and apparatus capable of reducing flicker during stereoscopic viewing as described above while leaving information useful for diagnosis.

  The radiological image acquisition apparatus of the present invention includes a radiological image acquisition unit that acquires radiographic images for each imaging direction detected by irradiating a subject with radiation from two different imaging directions, and a radiological image acquisition unit. An image processing unit that performs a blurring process on a region that exists only in one acquired radiographic image and does not exist in the other radiographic image is provided.

  In the radiological image acquisition apparatus of the present invention, the image processing unit may perform a restoration process for returning the radiographic image subjected to the blurring process to the radiographic image before the blurring process.

  In addition, it is possible to provide a display unit that switches and displays the radiographic image subjected to the blurring process and the radiographic image subjected to the restoration process.

  In addition, an image switching receiving unit that receives a selection instruction for whether the radiographic image is stereoscopically viewed or two-dimensionally provided is provided, and when the stereoscopic switching selection instruction is received by the image switching receiving unit, a blurring process is performed. The radiographic image subjected to the restoration process is displayed, and when the selection instruction for two-dimensional viewing is received in the image switching reception unit, the radiographic image subjected to the restoration process can be displayed.

  In addition, it is possible to provide a radiation image storage unit that stores a radiographic image before blurring processing, and a display unit that switches between a radiographic image subjected to blurring processing and a radiographic image before blurring processing.

  In addition, an image switching receiving unit that receives a selection instruction for whether the radiographic image is stereoscopically viewed or two-dimensionally provided is provided, and when the stereoscopic switching selection instruction is received by the image switching receiving unit, a blurring process is performed. When the radiographic image subjected to 2D viewing is displayed in the image switching accepting unit, the radiographic image before blurring processing is displayed.

  The radiological image acquisition method of the present invention acquires a radiographic image for each radiographing direction detected by irradiating a subject with radiation from two different radiographing directions, and exists only in the acquired radiographic image. A blurring process is performed on a region that is present and that does not exist in the other radiation image.

  According to the radiographic image acquisition method and apparatus of the present invention, a radiographic image for each radiographing direction detected by irradiating a subject with radiation from two different radiographing directions is acquired, and the acquired one radiation Since the blur processing is applied to the area that exists only in the image and does not exist in the other radiation image, the image information of the subject may be left to some extent in the blur area. Therefore, it can be effectively used for medical image diagnosis, and the above-described flicker can be reduced because the blurred region is not clearly recognized when stereoscopically viewed.

  Further, in the radiological image acquisition apparatus of the present invention, a restoration process for returning the radiographic image subjected to the blurring process to the radiographic image before the blurring process is also performed. When a radiographic image is displayed and a two-dimensional image is observed, if the radiographic image subjected to the restoration process is displayed, the medical image can be obtained by observing both the stereoscopic image and the two-dimensional image. The accuracy of image diagnosis can be improved, and the diagnostic accuracy can be further improved because blurring processing is not performed in medical image diagnosis using a two-dimensional view image. In addition, the same effect can be obtained by displaying the radiographic image before the blurring process instead of the radiographic image subjected to the restoration process.

1 is a schematic configuration diagram of a breast image photographing display system using an embodiment of a radiographic image photographing device of the present invention. The figure which shows the movement of the radiation source unit at the time of performing stereo imaging | photography of CC imaging | photography in the mammography imaging | photography display system shown in FIG. The figure which shows the movement of the radiation source unit at the time of performing the stereo imaging | photography of MLO imaging | photography in the mammography imaging | photography display system shown in FIG. 1 is a block diagram showing a schematic configuration inside a computer of the breast image capturing and displaying system shown in FIG. The flowchart for demonstrating the effect | action of the mammography imaging display system using one Embodiment of the radiographic imaging apparatus of this invention. The figure which shows the area | region which performs a blurring process with respect to the radiographic image for right eyes and the radiographic image for left eyes acquired by MLO imaging | photography. The figure which shows the area | region which performs a blurring process with respect to the radiographic image for right eyes and the radiographic image for left eyes acquired by CC imaging | photography

  Hereinafter, a breast image radiographing display system using an embodiment of a radiographic image radiographing apparatus of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of the entire breast image photographing display system of the present embodiment.

  As shown in FIG. 1, a breast image radiographing display system 1 according to the present embodiment includes a mammography apparatus 10, a computer 2 connected to the mammography apparatus 10, a monitor 3 connected to the computer 2, and an input unit. 4 is provided.

  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 be rotated. The arm part 13 connected with the base 11 is provided.

  The arm portion 13 has an alphabet C shape, and an imaging table 14 on which a breast is installed is attached to one end, and a radiation source unit 16 is attached to the other end so as to face the imaging table 14. The rotation and vertical movement of the arm unit 13 by the rotating shaft 12 are controlled by an arm controller 31 incorporated in the base 11.

  Further, in the central portion of the arm portion 13, the compression plate 18 is disposed above the imaging table 14 and presses the breast to press it, the support portion 20 that supports the compression plate 18, and the support portion 20 in the vertical direction. A moving mechanism 19 for moving is provided. The position of the compression plate 18 and the compression pressure are controlled by the compression plate controller 34.

  The mammography apparatus 10 of the present embodiment is configured to be able to perform stereo imaging of breast CC imaging (head-to-tail imaging) and MLO imaging (inside / outside oblique imaging). Has been. 1 and 2 show the posture of the arm unit 13 during CC imaging, and FIG. 3 shows the posture of the arm unit 13 during MLO imaging.

  In the mammography apparatus 10 of the present embodiment, when performing CC imaging stereo imaging, as shown in FIG. 2, the arm unit 13 is tilted by a predetermined angle + θ1 from the vertical direction and the vertical direction. Depending on the state, two radiographic images are taken. At this time, the imaging table 14 and the compression plate 18 are supported to be rotatable with respect to the arm unit 13, and the breast installation surface of the imaging table 14 and the compression surface of the compression plate 18 are maintained in a horizontal state. .

  In MLO imaging, as shown in FIG. 3, the arm unit 13 is installed at a predetermined imaging angle + θ2 of 45 ° or more and less than 90 °, and is inclined from the imaging angle + θ2 by a predetermined angle + θ1. Then, two radiographic images are taken. Note that the imaging table 14 and the compression plate 18 are supported so as to be rotatable with respect to the arm unit 13 as described above, and when performing MLO imaging, the breast mounting surface of the imaging table 14 and the compression surface of the compression plate 18 are: It shall be maintained in a state parallel to the direction orthogonal to the imaging angle + θ2.

  A radiographic image detector 15 such as a flat panel detector and a detector controller 33 that controls reading of a charge signal from the radiographic image detector 15 are provided inside the imaging table 14.

  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 radiation image detector 15 can repeatedly perform recording and reading of a radiation image, and may use a so-called direct type radiation image detector that directly receives radiation and generates charges. Alternatively, a so-called indirect 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 reading method, a radiation image signal is read by turning on / off a TFT (thin film transistor) switch, or by irradiating reading light. A so-called optical readout system in which a radiation image signal is read out can be used, but the invention is not limited to this, and other types may be used.

  A radiation source 17 and a radiation source controller 32 are housed in the radiation source unit 16. The radiation source controller 32 controls the timing of irradiating radiation from the radiation source 17 and the radiation generation conditions (tube current, time, tube voltage, etc.) in the radiation source 17.

  The computer 2 includes a central processing unit (CPU) and a semiconductor memory, a storage device such as a hard disk and an SSD, and the like. With these hardware, a control unit 40, a radiation image storage unit 41, an image as shown in FIG. A processing unit 42 and a display control unit 43 are configured.

  The control unit 40 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 41 stores two radiation image signals detected by the radiation image detector 15 by photographing from two different photographing directions.

  The image processing unit 42 receives the radiographic image for each imaging direction stored in the radiographic image storage unit 41, and is an area that exists only in one radiographic image as described above, and does not exist in the other radiographic image. Blur processing is performed on the area.

  That is, if the radiographic images for each imaging direction are respectively the right-eye radiographic image and the left-eye radiographic image, the right-eye radiographic image is an area that exists only in the right-eye radiographic image and does not exist in the left-eye radiographic image. A blurring process is performed on the region, and the left-eye radiographic image is a region that exists only in the left-eye radiographic image and is not present in the right-eye radiographic image. As the blurring process, for example, a smoothing process may be used, and a moving average method, a median filter process, or the like can be used.

  The display control unit 43 displays a breast stereo image on the monitor 3 after performing predetermined signal processing on the radiographic image subjected to the blurring process in the image processing unit 42.

  The input unit 4 is configured by a pointing device such as a keyboard and a mouse, for example, and includes predetermined shooting conditions such as CC shooting and MLO shooting, and instructions for selecting a stereo image display mode and a two-dimensional viewing image display mode. It accepts input by the photographer. The stereo image display mode and the two-dimensional viewing image display mode will be described in detail later.

  The monitor 3 is configured to be able to display a stereo image using two radiation image signals output from the computer 2. As a configuration for displaying a stereo image, for example, a radiographic image based on two radiographic image signals is displayed using two screens, and one of the radiographic images is observed by using a half mirror or a polarizing glass. 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. 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.

  Next, the operation of the breast image radiographing display system of this embodiment will be described with reference to the flowchart shown in FIG. Here, a case where stereo shooting of MLO shooting is performed will be described.

  First, predetermined photographing conditions including an instruction to select stereo photographing for MLO photographing are input by the photographer using the input unit 4 (S10).

  When the input unit 4 receives an instruction to select stereo shooting for MLO shooting, the control unit 40 reads preset shooting angles + θ2 and + θ1 for stereo shooting of MLO shooting, and provides information on the read shooting angles. Output to the arm controller 31. In this embodiment, it is assumed that + θ2 = 30 ° and + θ1 = 4 ° are stored in advance as information on the shooting angle + θ2, but the present invention is not limited to this. Can be set.

  Then, the arm controller 31 receives information on the photographing angles + θ2 = 30 ° and + θ1 = 4 ° output from the control unit 40, and the arm controller 31 first receives the control signal output from the control unit 40. Based on the information of + θ2 = 30 °, a control signal is output so that the arm portion 13 is inclined by 30 ° from a direction perpendicular to the imaging table 14 as shown in FIG.

  Then, according to the control signal output from the arm controller 31, the arm unit 13 is inclined by 30 ° from the direction perpendicular to the imaging table 14. In this state, the test object is placed on the imaging table 14. The breast of the person M is installed, and the breast is compressed with a predetermined pressure by the compression plate 18 (S12).

  Next, when an imaging start instruction is input by the photographer after the breast has been installed, the first radiographic image of the two radiographic images constituting the stereo image is captured (S14).

  Specifically, the control unit 40 outputs a control signal to the radiation source controller 32 and the detector controller 33 so as to perform radiation irradiation and readout of the radiation image signal. In response to this control signal, radiation is emitted from the radiation source 17, a radiation image obtained by photographing the breast from a direction perpendicular to the breast installation surface is detected by the radiation image detector 15, and a radiation image signal is detected by the detector controller 33. After being read out and subjected to predetermined signal processing on the radiation image signal, it is stored in the radiation image storage unit 41 of the computer 2 (S16).

  Subsequently, as shown in FIG. 3, the arm controller 31 outputs a control signal so that the arm unit 13 rotates by + θ1 from a state where the arm unit 13 is inclined by 30 ° with respect to a direction perpendicular to the imaging table 14. That is, in the present embodiment, the control signal is output so that the arm portion 13 is further rotated by + θ1 = 4 ° from a state in which the arm portion 13 is inclined by 30 ° with respect to the direction perpendicular to the imaging table 14.

  Then, in a state in which the arm unit 13 is further rotated by 4 ° according to the control signal output from the arm controller 31, the control unit 40 applies radiation to the radiation source controller 32 and the detector controller 33 and the radiation image signal. A control signal is output so as to read out. In accordance with this control signal, radiation is emitted from the radiation source 17, and a radiation image obtained by photographing the breast from a direction inclined by 4 ° with respect to the vertical direction of the breast installation surface is detected by the radiation image detector 15, The radiographic image signal is read by the detector controller 33, subjected to predetermined signal processing, and then stored in the radiographic image storage unit 41 of the computer 2 (S18).

  As described above, the radiographic image captured from the vertical direction with respect to the breast installation surface and the radiographic image captured from the direction inclined by 4 ° from the vertical direction are read from the radiographic image storage unit 41 and image processing unit 42. Is input.

  Then, in the image processing unit 42, the blurring process is performed on these two radiation images as described above (S20). FIG. 6 shows a radiographic image taken from a direction perpendicular to the breast installation surface when a radiographic image for the right eye is used, and a radiographic image taken from a direction inclined by 4 ° from the vertical direction is used as a radiographic image for the left eye. The area to which the blurring process is applied is shown in gray. Note that the region to be subjected to the blurring process is set based on the distance between the radiation source 17 and the breast, the distance between the radiation source 17 and the radiation image detector 15 (breast compression thickness), and two imaging angles. Is.

  Then, the right-eye radiographic image and the left-eye radiographic image subjected to the blurring process in the image processing unit 42 are input to the display control unit 43, and the display control unit 43 performs predetermined processing on these radiographic image signals. After being applied, it is output to the monitor 3. Then, on the monitor 3, the radiographic image for the right eye and the radiographic image for the left eye are respectively displayed, and a stereo image of the breast is displayed (S22).

  According to the breast image radiographing display system of the above-described embodiment, a radiographic image for each radiographing direction detected by irradiating radiation to the breast from two mutually different radiographing directions is acquired, and the acquired one radiation Since the blur processing is applied to the area that exists only in the image and does not exist in the other radiation image, the image information of the breast may be left to some extent in the blur area. Therefore, it can be effectively used for medical image diagnosis, and the above-described flicker can be reduced because the blurred region is not clearly recognized when stereoscopically viewed.

  Further, in the above-described embodiment, the case of stereo imaging of MLO imaging has been described. Similarly, in the case of stereo imaging of CC imaging, a radiographic image captured from the vertical direction with respect to the breast installation surface and 4 from the vertical direction thereof. The radiation image taken from the tilted direction may be blurred and displayed on the monitor 3. FIG. 7 shows that in CC imaging, a blurring process is performed on a right-eye radiographic image captured from a direction perpendicular to the breast installation surface and a left-eye radiographic image captured from a direction inclined by 4 ° from the vertical direction. The area is shown in gray.

  In the above embodiment, the operation of displaying a stereo image on the monitor 3 has been described. However, not only the stereo image but also a two-dimensional image for two-dimensional viewing may be displayed on the monitor 3.

  Specifically, for example, when the input unit 4 receives a selection instruction for the stereo image display mode or the two-dimensional viewing image display mode, and receives a selection instruction for the stereo image display mode, the blur processing is performed as described above. When both the radiographic image for the right eye and the radiographic image for the left eye displayed are displayed on the monitor 3 and the selection instruction for the two-dimensional viewing image display mode is received, the radiograph is taken from the direction perpendicular to the breast installation surface. Alternatively, only the right-eye radiographic image may be displayed on the monitor 3 as a two-dimensional view image.

  In addition, since the two-dimensional image displayed on the monitor 3 in the two-dimensional image display mode is not stereoscopically viewed, it is not necessary to perform the blurring process as described above. Since it is necessary to observe even a fine part, it is desirable that the radiation image be before blurring.

  Therefore, the image processing unit 42 performs a restoration process for returning to the right-eye radiographic image before the blurring process on the right-eye radiographic image subjected to the blurring process in the image processing unit 42, and the restoration process is performed. It is desirable to display the right-eye radiation image on the monitor 3 as a two-dimensional viewing image. In addition, as this restoration process, an inverse filter process, a Wiener filter process, a least square filter process, or the like can be used. Further, returning to the radiation image before the blurring process does not necessarily return completely, and the restoration process may be a process that brings the radiation image before the blurring process closer.

  Further, the method for displaying the right-eye image before the blurring process is not limited to the method of performing the restoration process as described above. For example, in order to perform the blurring process in the image processing unit 42, the radiation image is stored from the radiation image storage unit 41. Is read out, the right-eye radiographic image before blurring processing is stored in the radiographic image storage unit 41, and the two-dimensional view image is displayed using the stored right-eye radiographic image before blurring processing. May be.

  In the above description, in the two-dimensional viewing image display mode, only the right-eye radiographic image captured from the direction perpendicular to the breast installation surface is displayed as a two-dimensional viewing image. When the screen is composed of two separate screens for the right eye and the left eye, either the right-eye radiation image or the left-eye radiation image before the blurring process or after the restoration process is two-dimensionally displayed on the two screens. You may make it display as a visual image.

  Further, the breast imaging apparatus of the above-described embodiment performs imaging of the right-eye radiation image and the left-eye radiation image by moving the radiation source unit 16 in the left-right direction in front of the subject M. For example, the radiation source unit 16 is moved in the front-rear direction of the subject M, that is, in the direction away from the chest wall of the subject M, and the right-eye radiation image and the left-eye radiation image are captured. Also good. Even in this case, for the right-eye radiographic image, the region that exists only in the right-eye radiographic image and that does not exist in the left-eye radiographic image is subjected to blurring processing. The blur processing may be performed on a region that exists only in the left-eye radiographic image and does not exist in the right-eye radiographic image.

  In the above embodiment, the case where the radiographic image acquisition apparatus of the present invention is applied to a breast image radiographing display system has been described. However, the radiographic image acquisition apparatus of the present invention is not limited to an apparatus for imaging a breast, and other The present invention can also be applied to an imaging apparatus that images other parts such as the chest and head of the body.

DESCRIPTION OF SYMBOLS 1 Mammography imaging display system 2 Computer 3 Monitor 4 Input part 10 Mammography apparatus 13 Arm part 14 Imaging stand 15 Radiation image detector 16 Radiation source unit 17 Radiation source 18 Compression plate 40 Control part 41 Radiation image storage part 42 Image processing Part 43 Display control part

Claims (7)

A radiological image acquisition unit that acquires radiographic images for each of the imaging directions detected by irradiating the subject with radiation from two different imaging directions;
An image processing unit that performs blurring processing on a region that exists only in one of the radiographic images acquired by the radiological image acquisition unit and does not exist in the other radiographic image. Radiation image acquisition device.   The radiographic image acquisition apparatus according to claim 1, wherein the image processing unit performs a restoration process for returning the radiographic image subjected to the blurring process to the radiographic image before the blurring process.   The radiographic image acquisition apparatus according to claim 2, further comprising a display unit configured to switch and display the radiographic image subjected to the blurring process and the radiographic image subjected to the restoration process. An image switching reception unit that receives a selection instruction to stereoscopically or two-dimensionally view the radiation image;
When the display switching instruction is received by the image switching reception unit, the display unit displays the blurred radiographic image, and the image switching reception unit selects the two-dimensional viewing. The radiographic image acquisition apparatus according to claim 3, wherein when an instruction is accepted, the radiographic image subjected to the restoration process is displayed. A radiation image storage unit for storing the radiation image before the blurring process;
The radiographic image acquisition apparatus according to claim 1, further comprising: a display unit that switches and displays the radiographic image subjected to the blurring process and the radiographic image before the blurring process. An image switching reception unit that receives a selection instruction to stereoscopically or two-dimensionally view the radiation image;
When the display switching instruction is received by the image switching reception unit, the display unit displays the blurred radiographic image, and the image switching reception unit selects the two-dimensional viewing. 6. The radiological image acquisition apparatus according to claim 5, wherein when an instruction is received, the radiographic image before the blurring process is displayed. Obtaining a radiation image for each of the photographing directions detected by irradiating the subject with radiation from two different photographing directions;
A radiological image acquisition method comprising performing blurring processing on a region that exists only in one acquired radiological image and does not exist in the other radiographic image.