JP2012170670A - Radiation imaging apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the radiation dose to which a subject is exposed, and to reduce the total capacity of acquired stereoscopic vision images in performing polynocular stereoscopic vision imaging.SOLUTION: Stereoscopic imaging is performed from a plurality of reference imaging directions to acquire polynocular stereoscopic images. At this time, at least one imaging condition is set out of: an imaging condition in which a radiation dose in imaging the subject from a reference imaging direction D2 of facing the subject from the front is made larger than radiation doses from other reference imaging directions D1, D3; an imaging condition in which a grid is used only when imaging from at least one imaging direction in imaging from the reference imaging direction D2; an imaging condition in which the resolution of radiation images acquired by imaging from the reference imaging directions D1, D3 is made lower than that of radiation images acquired by imaging from the reference imaging direction D2; and an imaging condition in which the density resolution of the radiation images acquired by imaging from the reference imaging directions D1, D3 is made lower than that of the radiation images acquired by imaging from the reference imaging direction D2.

Description

  The present invention relates to a radiographic image capturing apparatus and method for capturing a radiographic image for displaying a stereoscopic image of a subject.

  As an apparatus for displaying a medical image such as a radiographic image, an apparatus for displaying a stereoscopic image (three-dimensional image, stereo image) based on stereoscopic image data including parallax information between the left and right eyes has been proposed. Such a stereoscopic image is obtained by irradiating a subject with radiation from different directions, detecting radiation transmitted through the subject with a radiation detector, and obtaining a plurality of radiation images having parallax with each other. Based on the image, it is displayed three-dimensionally so as to be stereoscopically viewable. Thus, by displaying the stereoscopic image in a three-dimensional manner so as to be stereoscopically viewed, it is possible to observe a radiographic image with a sense of depth, thereby making diagnosis easier.

  By the way, a multi-lens photographing device has been proposed as a device for photographing an image for displaying a stereoscopic image. The multi-view photographing device performs multi-view stereoscopic photographing that acquires a plurality of sets of images composed of two images for displaying a stereoscopic image at each of a plurality of photographing positions. Then, a plurality of sets of images acquired by such a multi-lens imaging device are three-dimensionally displayed on a three-dimensional display device provided with a lenticular, thereby observing a stereoscopic image from a direction corresponding to each imaging direction. be able to. In this way, when a stereoscopic image is displayed with multiple eyes, it is peculiar to the case where stereoscopic vision is performed as compared with the case where a stereoscopic image is displayed using an image acquired by photographing at only one place. It is known that fatigue when observing a stereoscopic image can be reduced because the discrepancy between convergence and adjustment is reduced.

  It has also been proposed to apply such a multi-view imaging device to a radiographic image (see Patent Document 1). Also, a method has been proposed in which a plurality of shooting directions are set, and from which shooting direction a stereoscopic image is shot is determined according to shooting parameters (see Patent Document 2).

  By the way, when taking a radiographic image, there is a case where a grid is arranged in front of the radiation detector in order to prevent scattering of radiation by the subject, but two radiographic images for displaying a stereoscopic image are displayed. When acquiring, it is necessary to irradiate the subject with radiation from different directions. For example, it is necessary to perform imaging from an imaging direction having a predetermined angle with respect to the front of the subject and the front. Here, when the grid is used when irradiating the subject from a direction having a predetermined angle with respect to the front, the attenuation of the radiation by the grid increases, so that it is necessary to increase the radiation dose. However, increasing the radiation dose increases the exposure of the subject. For this reason, a method has been proposed in which the grid is used only for shooting from the front and the shooting is performed without using the grid for shooting from an angled direction (see Patent Document 3).

  In addition, in a radiographic imaging device, in order to observe the affected area in more detail, the radiation source is moved, the subject is irradiated with radiation from a plurality of different directions, and imaging is performed. Tomosynthesis photography that can obtain an image in which the cross section is emphasized has been proposed. In tomosynthesis imaging, depending on the characteristics of the imaging device and the required tomographic image, the radiation source can be moved in parallel with the radiation detector, or moved in a circle or ellipse arc to create different irradiation angles. A plurality of radiographic images are acquired by imaging the subject at the irradiation position, and a tomographic image is generated by reconstructing these radiographic images using a simple backprojection method or a backprojection method such as a filter backprojection method. .

  In performing such tomosynthesis imaging, a method has been proposed in which the radiation intensity from the direction perpendicular to the detection surface of the radiation detector is made larger than the radiation intensity from other directions (see Patent Document 4). In addition, when performing tomosynthesis imaging, there has also been proposed a method for correcting a radiographic image in order to compensate for differences in image quality of a plurality of acquired images when radiation doses from a plurality of imaging directions differ (patent) Reference 5).

JP 2008-116790 A JP 2006-212056 A JP 2010-233858 A JP 2007-75615 A JP 2010-119507 A

  When performing the above-described tomosynthesis imaging, as described in Patent Document 4, the radiation intensity can be reduced according to the imaging direction, whereby the exposure dose to the subject can be reduced. However, it has not been proposed to reduce the exposure dose to the subject by changing the radiation intensity according to the imaging direction when performing the above-described multi-view stereoscopic imaging. Furthermore, it has not been proposed to reduce the total capacity of radiographic images acquired by multi-view imaging.

  The present invention has been made in view of the above circumstances, and an object thereof is to reduce the exposure dose to a subject when performing multi-view stereoscopic imaging.

  Another object of the present invention is to reduce the total volume of radiographic images acquired when performing multi-view stereoscopic imaging.

A radiographic imaging apparatus according to the present invention includes a radiation irradiating means for irradiating a subject with radiation,
Radiation detecting means for detecting the radiation irradiated by the radiation irradiating means and transmitted through the subject and outputting a radiation image of the subject;
In order to acquire a plurality of stereoscopic images of the subject viewed from a plurality of viewpoints, the subject is irradiated with the radiation from two imaging directions having a predetermined convergence angle in each of a plurality of reference imaging directions. Imaging control means for performing multi-view stereoscopic imaging by detecting two radiation images by the radiation detection means;
Of the plurality of reference imaging directions, an imaging condition for making the radiation dose at the time of imaging from a reference imaging direction facing the subject from the front larger than an imaging dose at the time of imaging from another reference imaging direction, Imaging conditions that use a grid only when imaging from at least one imaging direction when imaging from the reference imaging direction facing from the front, and the two radiation images acquired by imaging from the reference imaging direction facing the subject from the front In contrast, the imaging conditions for lowering the resolution of the two radiographic images acquired by imaging from the other reference imaging direction, and the two radiographic images acquired by imaging from the other reference imaging direction On the other hand, at least one of the imaging conditions for lowering the density resolution of the two radiographic images acquired by imaging from the other reference imaging direction. It is characterized in that a shooting condition setting means for setting an imaging condition.

  When imaging is performed according to “imaging conditions using a grid only when imaging from at least one imaging direction when imaging from the reference imaging direction facing the subject from the front”, the grid is not used when imaging from another reference direction. It will not be used.

  The radiographic image capturing apparatus according to the present invention may further include display means for displaying a multi-view stereoscopic image based on the two radiographic images acquired in each of the plurality of reference imaging directions.

  In this case, the display means has a stereoscopic image acquired by imaging from the other reference imaging direction around the stereoscopic image acquired by imaging from the reference imaging direction facing the subject from the front. It is good also as a means to display.

A radiation image display method according to the present invention includes radiation irradiating means for irradiating a subject with radiation,
An imaging method in a radiographic imaging apparatus, comprising: a radiation detection unit that detects radiation that has been irradiated by the radiation irradiation unit and transmitted through the subject, and outputs a radiation image of the subject,
In order to acquire a plurality of stereoscopic images of the subject viewed from a plurality of viewpoints, the subject is irradiated with the radiation from two imaging directions having a predetermined convergence angle in each of a plurality of reference imaging directions. When performing multi-view stereoscopic imaging by detecting two radiation images by the radiation detection means,
Of the plurality of reference imaging directions, an imaging condition for making the radiation dose at the time of imaging from a reference imaging direction facing the subject from the front larger than an imaging dose at the time of imaging from another reference imaging direction, Imaging conditions that use a grid only when imaging from at least one imaging direction when imaging from the reference imaging direction facing from the front, and the two radiation images acquired by imaging from the reference imaging direction facing the subject from the front In contrast, the imaging conditions for lowering the resolution of the two radiographic images acquired by imaging from the other reference imaging direction, and the two radiographic images acquired by imaging from the other reference imaging direction On the other hand, at least one of the imaging conditions for lowering the density resolution of the two radiographic images acquired by imaging from the other reference imaging direction. It is characterized in that setting the imaging conditions.

  When displaying a multi-view stereoscopic image, a stereoscopic image acquired by imaging from the reference imaging direction facing the subject from the front is mainly used for observation, and a stereoscopic image acquired by imaging from other reference imaging directions is used. The visual image is used as an auxiliary. For this reason, the stereoscopic image acquired by imaging from another reference imaging direction is not required to have the same image quality as the stereoscopic image acquired by imaging from the reference imaging direction facing the subject from the front, and the other reference imaging directions are not required. Even if the image quality of the stereoscopic image acquired by shooting from is somewhat poor, it does not affect multi-view stereoscopic viewing.

  According to the present invention, when performing multi-view stereoscopic imaging, the radiation dose at the time of imaging from the reference imaging direction facing the subject from the front among the plurality of reference imaging directions is determined at the time of imaging from other reference imaging directions. An imaging condition that is larger than the imaging dose, an imaging condition that uses the grid only when imaging from at least one imaging direction when imaging from the reference imaging direction facing the subject from the front, and a reference imaging direction facing the subject from the front For the two radiographic images acquired by the above imaging, the imaging conditions for lowering the resolution of the two radiographic images acquired by imaging from other reference imaging directions, and the reference imaging direction facing the subject from the front Among the imaging conditions for lowering the density resolution of two radiographic images acquired by imaging from other reference imaging directions with respect to two radiographic images acquired by imaging It is obtained so as to set at least one photographing condition.

  For this reason, by setting an imaging condition that makes the radiation dose at the time of imaging from the reference imaging direction facing the subject larger than the imaging dose at the time of imaging from other reference imaging directions, multi-view stereoscopic viewing is achieved. The exposure dose to the subject can be reduced without affecting the subject.

  In addition, by setting the shooting conditions to use the grid only when shooting from at least one shooting direction when shooting from the reference shooting direction facing the subject from the front, shooting from the reference shooting direction facing the subject from the front Sometimes it is possible to remove the scattered radiation from the grid, but it is not necessary to increase the radiation dose when taking images from other reference imaging directions. Can be reduced.

  In addition, an imaging condition for lowering the resolution of two radiographic images acquired by imaging from other reference imaging directions is lower than two radiographic images acquired by imaging from the standard imaging direction facing the subject from the front. By setting, it is possible to reduce the capacity of two radiographic images acquired by imaging from other reference imaging directions, so that radiation acquired by multi-view stereoscopic imaging without affecting multi-view stereoscopic viewing The total capacity of the image can be reduced.

  Also, an imaging condition that lowers the density resolution of two radiographic images acquired by imaging from other reference imaging directions with respect to two radiographic images acquired by imaging from the standard imaging direction facing the subject from the front. Since it is possible to reduce the capacity of two radiographic images acquired by imaging from other reference imaging directions, it is acquired by multi-view stereoscopic shooting without affecting multi-view stereoscopic viewing. The total capacity of the radiographic image can be reduced.

1 is a schematic configuration diagram of a radiographic imaging device according to an embodiment of the present invention. The figure which looked at the arm part of the radiographic imaging apparatus shown in FIG. 1 from the right direction of FIG. The block diagram which shows schematic structure inside the computer of the radiographic imaging apparatus shown in FIG. Diagram for explaining multi-eye stereo shooting The figure for demonstrating the display of a multi-eye stereo image A flowchart showing processing performed in the present embodiment

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a radiographic imaging apparatus according to an embodiment of the present invention. The radiographic image capturing apparatus 1 acquires a plurality of radiographic images by capturing the breast M from different imaging directions in order to display a stereo image for stereoscopically viewing the radiographic image of the breast. In particular, multi-eye stereo photography is performed to display a multi-eye stereo image that can form a stereo image from a plurality of directions. As shown in FIG. 1, the radiographic imaging device 1 includes an imaging unit 10, a computer 2 connected to the imaging unit 10, a monitor 3 connected to the computer 2, and an input unit 4.

  The imaging unit 10 includes a base 11, a rotary shaft 12 that is movable in the vertical direction (Z direction) with respect to the base 11, and a rotatable rotation shaft 12 and an arm portion 13 that is connected to the base 11 by the rotation shaft 12. I have. FIG. 2 shows the arm 13 viewed from the right direction in FIG.

  The arm portion 13 has an alphabet C shape, and a radiation table 16 is attached to one end of the arm portion 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 detector 15 such as a flat panel detector and a detector controller 33 that controls reading of a charge signal from the radiation detector 15 are provided inside the imaging table 14.

  The imaging table 14 includes a charge amplifier that converts the charge signal read from the radiation detector 15 into a voltage signal, a correlated double sampling circuit that samples the voltage signal output from the charge amplifier, and a voltage signal. A circuit board or the like provided with an AD conversion unit for converting into a digital signal is also installed.

  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.

  The radiation detector 15 can repeatedly perform recording and reading of a radiation image, and may use a so-called direct type radiation detector that directly receives radiation to generate charges, or radiation. May be used as a so-called indirect radiation detector that converts the light into visible light and converts the visible light into a charge signal. 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 a radiation image is emitted by irradiating reading light. It is desirable to use a so-called optical readout system in which a signal is read out, but the present invention is not limited to this, and other systems may be used.

  A radiation source 17 and a radiation source controller 32 are housed inside 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 current, time, tube voltage, etc.) in the radiation source 17.

  Further, in the central portion of the arm portion 13, a compression plate 18 that is disposed above the imaging table 14 and presses against the breast M, a support portion 20 that supports the compression plate 18, and a support portion 20 are arranged 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.

  A grid 24 for removing scattered radiation of radiation that has passed through the breast M is disposed above the imaging table 14. In order to prevent the radiation scattered by the breast M from irradiating the radiation detector 15, the grid 24 is made of lead or the like that does not transmit radiation at a fine pitch of, for example, about 10 pieces / mm and aluminum or wood that easily transmits. They are arranged alternately. The grid 24 can be taken in and out of the imaging table 14 by a grid controller 35. The grid controller 35 operates according to the photographing conditions set by the operator, and puts the grid 24 in and out of the photographing table 14. Note that the operator may operate by giving an instruction from the input unit 4 to be described later, and the grid 24 may be moved in and out of the imaging table 14.

  The computer 2 includes a central processing unit (CPU) and a storage device such as a semiconductor memory, a hard disk, and an SSD. The control unit 2a, the radiation image storage unit 2b, and the radiographing unit shown in FIG. A condition setting unit 2c and a display control unit 2d are configured.

  The control part 2a outputs a predetermined control signal with respect to various controllers 31-35, and controls the whole apparatus. A specific control method will be described later. Note that the control unit 2a corresponds to a photographing control unit.

  The radiation image storage unit 2b stores a plurality of radiation images acquired by multi-eye stereo imaging. Here, the multi-eye stereo imaging performed in the present embodiment will be described. FIG. 4 is a diagram for explaining multi-eye stereo shooting. As shown in FIG. 4, multi-eye stereo shooting is performed by performing stereo shooting from a plurality of (three in the present embodiment) shooting directions (hereinafter referred to as reference shooting directions) D1 to D3. In the present embodiment, the reference imaging direction D2 is the direction of the perpendicular of the radiation detector 15 (that is, the Z direction), and the reference imaging directions D1 and D3 are −θ1 degrees and + θ1 with respect to the Z direction (0 degrees), respectively. The direction is inclined at a degree.

  In this embodiment, in each of the reference imaging directions D1 to D3, imaging is performed from two imaging directions based on the reference imaging direction, and two radiation images are acquired. For example, in the reference imaging direction D1, imaging is performed from each of two imaging directions D1-1 and D1-2 that form an angle θ0 (convergence angle) with respect to the reference imaging direction D1, and two radiation images G1-1 and G1 are taken. Get G1-2. In the reference imaging direction D2, imaging is performed from each of the two imaging directions D2-1 and D2-2 that form the convergence angle θ0 with respect to the reference imaging direction D2, and two radiation images G2-1 and G2-2 are acquired. To do. In the reference imaging direction D3, imaging is performed from each of the two imaging directions D3-1 and D3-2 that form the convergence angle θ0 with respect to the reference imaging direction D3, and two radiation images G3-1 and G3-2 are acquired. To do.

  The shooting condition setting unit 2c sets different shooting conditions for each of the reference shooting directions D1 to D3 when performing multi-eye stereo shooting. In the present embodiment, at least one of the following four shooting conditions is set according to an instruction from the input unit 4 by the operator.

1. Of the reference imaging directions D1 to D3, the radiation dose at the time of imaging from the reference imaging direction D2 facing the breast M from the front is made larger than the imaging dose at the time of imaging from the other reference imaging directions D1 and D3. Shooting conditions.

2. Of the reference photographing directions D1 to D3, the grid 24 is used only when photographing from the reference photographing direction D2 facing the breast M from the front, and the grid 24 is not used when photographing from the other reference photographing directions D1 and D3. Shooting conditions.

3. Radiation images G1 acquired by imaging from the other reference imaging directions D1 and D3 with respect to the two radiation images G2-1 and G2-2 acquired by imaging from the reference imaging direction D2 facing the breast M from the front. Third imaging condition for reducing the resolution of -1, G1-2, G3-1, and G3-2.

4). Radiation images G1 acquired by imaging from the other reference imaging directions D1 and D3 with respect to the two radiation images G2-1 and G2-2 acquired by imaging from the reference imaging direction D2 facing the breast M from the front. Third imaging condition for reducing density resolution of -1, G1-2, G3-1, and G3-2.

  As for the first imaging condition, in this embodiment, since imaging is performed from three reference imaging directions D1 to D3, the radiation dose at the time of imaging from the reference imaging directions D1 and D3 is set as the reference imaging. It is set to 1/3 of the radiation dose at the time of imaging from the direction D2. Regarding the third imaging condition, the radiographic image acquired by imaging from the reference imaging directions D1 and D3 with respect to the resolution of the radiographic images G2-1 and G2-2 acquired by imaging from the reference imaging direction D2. The resolution of G1-1, G1-2, G3-1, and G3-2 is halved. As for the fourth imaging condition, when the density resolution of the radiation images G2-1 and G2-2 acquired by imaging from the reference imaging direction D2 is set to 14 bits, for example, the imaging from the reference imaging directions D1 and D3 is performed. The density resolution of the acquired radiation images G1-1, G1-2, G3-1, and G3-2 is set to 10 bits. The radiation dose, resolution, and concentration resolution are not limited to the above values, and arbitrary values can be adopted.

  The display control unit 2d performs predetermined processing on the six radiographic images G1-1, G1-2, G2-1, G2-2, G3-1, and G3-2 read from the radiographic image storage unit 2b. After the application, a multi-view stereo image of the breast M is displayed on the monitor 3.

  The monitor 3 can display a multi-view stereo image using the six radiation images G1-1, G1-2, G2-1, G2-2, G3-1, and G3-2 output from the computer 2. It is configured. Specifically, the monitor 3 includes a lenticular 3A. As shown in FIG. 5, the radiation images G1-1, G1-2, G2-1, and G2- at the corresponding positions on one lens of the lenticular 3A. 2, G3-1 and G3-2 are displayed on the monitor 3 so as to be divided into strips and arranged so that the stereo image of the breast M can be viewed stereoscopically from three directions.

  Thereby, when the multi-view stereo image displayed on the monitor 3 is viewed from the direction corresponding to the reference imaging direction D1, the stereo image based on the radiation images G1-1 and G1-2 is stereoscopically viewed. In addition, when the multi-view stereo image displayed on the monitor 3 is viewed from the direction corresponding to the reference imaging direction D2, the stereo image based on the radiation images G2-1 and G2-2 is stereoscopically viewed. Further, when the multi-view stereo image displayed on the monitor 3 is viewed from the direction corresponding to the reference photographing direction D3, the stereo image based on the radiation images G3-1 and G3-2 is stereoscopically viewed.

  The input unit 4 is configured by a pointing device such as a keyboard and a mouse, for example, and receives an input of shooting conditions and an input of a shooting start instruction by an operator.

  Next, processing performed in the present embodiment will be described. FIG. 6 is a flowchart showing processing performed in the present embodiment. First, the patient's breast M is placed on the imaging table 14, and the breast M is compressed with a predetermined pressure by the compression plate 18 (step ST1). Next, after the type of shooting condition to be used is input at the input unit 4, an instruction to start shooting is input (step ST2).

  When there is an instruction to start imaging at the input unit 4, multi-eye stereo imaging of the breast M is performed. Specifically, first, the control unit 2a resets the reference imaging direction for moving the radiation source 17 (i = 1, step ST3), and the radiation source 17 at the radiation source position Pi that becomes the current reference imaging direction Di. Is read from the storage device of the computer 2, and information on the read shooting direction angle αi is output to the arm controller 31. In this embodiment, α1 = −θ1 degrees when i = 1, α2 = 0 degrees when i = 2, and α3 = + θ1 degrees when i = 3. Then, the arm controller 31 receives the information on the shooting direction angle αi output from the control unit 2 a, and the arm controller 31 outputs a control signal for rotating the arm unit 13 to the arm controller 31. Here, when i = 1, as shown in FIG. 4, a control signal for rotating the arm unit 13 is output to the arm controller 31 so that the radiation source 17 moves to the radiation source position P1 in the reference imaging direction D1. . Then, in response to the control signal output from the arm controller 31, the arm unit 13 rotates to move the radiation source 17 to the radiation source position Pi that is the current reference imaging direction Di (step ST4).

  Next, shooting conditions for the current reference shooting direction Di are set by the shooting condition setting unit 2c (step ST5). In the present embodiment, since at least one of the first to fourth imaging conditions described above is specified by the operator, the specified imaging conditions are set.

  Then, stereo shooting is performed in the current reference shooting direction Di according to the set shooting conditions (step ST6). Specifically, first, the control unit 2a reads the convergence angle θ0 that defines the imaging direction for acquiring the two radiation images Gi-1 and Gi-2 in the reference imaging direction Pi, and the read convergence angle θ0. Is output to the arm controller 31. In this embodiment, it is assumed that θ0 = 4 degrees is stored in advance as information on the convergence angle θ0 at this time. However, the present invention is not limited to this, and an arbitrary convergence angle is set by the operator in the input unit 4. Is possible.

  Then, the arm controller 31 receives the information of the convergence angle θ0 output from the control unit 2a, and the arm controller 31 outputs a control signal for rotating the arm unit 13 to the arm controller 31. Here, when i = 1, as shown in FIG. 4, the radiation source position P1-1 becomes the imaging direction D1-1 of −θ0 / 2 degrees (ie, −2 degrees) with respect to the reference imaging direction D1. A control signal for rotating the arm unit 13 so that the radiation source 17 moves is output to the arm controller 31. In response to the control signal output from the arm controller 31, the arm unit 13 rotates to move the radiation source 17 to the imaging position Pi-1.

  In this state, the control unit 2a outputs a control signal to the radiation source controller 32 and the detector controller 33 so as to irradiate the radiation and read out the radiation image signal. In response to this control signal, radiation is emitted from the radiation source 17, a radiation image obtained by imaging the breast M from the radiation source position Pi- 1 is detected by the radiation detector 15, and the radiation from the radiation detector 15 is detected by the detector controller 33. The image signal is read out, subjected to predetermined signal processing on the radiation image signal, and then stored as a radiation image Gi-1 in the radiation image storage unit 2b of the computer 2.

  Next, the arm controller 31 outputs a control signal so that the arm unit 13 is rotated by + θ0 / 2 degrees from the shooting position Pi in the reference shooting direction Di. In response to the control signal output from the arm controller 31, the arm unit 13 rotates to move the radiation source 17 to the imaging position Pi-2.

  In this state, the control unit 2a outputs a control signal to the radiation source controller 32 and the detector controller 33 so as to irradiate the radiation and read out the radiation image signal. In response to this control signal, radiation is emitted from the radiation source 17, a radiation image obtained by imaging the breast M from the radiation source position Pi- 2 is detected by the radiation detector 15, and the radiation from the radiation detector 15 is detected by the detector controller 33. The image signal is read out, subjected to predetermined signal processing on the radiation image signal, and then stored as a radiation image Gi-2 in the radiation image storage unit 2b of the computer 2.

  Next, the control unit 2a determines whether or not shooting from all the reference shooting directions has been completed (step ST7). If step ST7 is negative, the shooting direction is set to the next shooting direction (i = i + 1), step ST8), and return to step ST4, and the processing after step ST4 is repeated.

  Here, when the first imaging condition is set as the imaging condition at the time of stereo imaging, the radiation dose at the time of imaging from the reference imaging direction D2 facing the breast M from the front among the reference imaging directions D1 to D3. The imaging is performed with the imaging dose larger than the imaging dose at the time of imaging from the other reference imaging directions D1 and D3.

  When the second imaging condition is set, imaging is performed using the grid 24 only during imaging from the reference imaging direction D2 where the breast M is viewed from the front among the reference imaging directions D1 to D3. Specifically, when the grid 24 is used, the control unit 2a outputs a control signal to the grid controller 35 so that the grid 24 is positioned on the imaging table 14, and according to the control signal, The grid 24 is moved onto the photographing table 14 and photographing is performed. On the contrary, when the grid 24 is not used, the control unit 2a outputs a control signal to the grid controller 35 so that the grid 24 is retracted from the imaging table 14, and the grid 24 captures an image according to the control signal. The image is taken away from the table 14.

  Note that when shooting is performed using the grid 24, the grid 24 may be used only when shooting from one of the two shooting directions Di-1 and Di-2.

  When the third imaging condition is set, another reference imaging direction is applied to the two radiographic images G2-1 and G2-2 acquired by imaging from the reference imaging direction D2 facing the breast M from the front. The resolutions of the radiation images G1-1, G1-2, G3-1, and G3-2 acquired by photographing from D1 and D3 are lowered. Thereby, the capacity | capacitance of radiographic image G1-1, G1-2, G3-1, G3-2 becomes smaller than the capacity | capacitance of radiographic image G2-1, G2-2.

  When the fourth imaging condition is set, another reference imaging direction is applied to the two radiographic images G2-1 and G2-2 acquired by imaging from the reference imaging direction D2 facing the breast M from the front. The density resolution of the radiation images G1-1, G1-2, G3-1, and G3-2 acquired by photographing from D1 and D3 is lowered. Thereby, the capacity | capacitance of radiographic image G1-1, G1-2, G3-1, G3-2 becomes smaller than the capacity | capacitance of radiographic image G2-1, G2-2.

  If step ST7 is affirmed, the radiographic images G1-1, G1-2, G2-1, G2-2, and G3- acquired in each of the three reference imaging directions D1 to D3 stored in the radiographic image storage unit 2b. 1 and G3-2 are read out, a predetermined process is performed on these radiographic images in the display control unit 2d, and then output to the monitor 3. A multi-view stereo image of the breast M is displayed on the monitor 3 (Step ST9).

  Here, when displaying a multi-view stereo image, a stereo image acquired by photographing from the reference photographing direction D2 facing the breast M from the front is mainly used for observation, and from other reference photographing directions D1 and D3. A stereo image acquired by photographing is used as an auxiliary. For this reason, the stereo image acquired by imaging from the other reference imaging directions D1 and D3 is not required to have the same image quality as the stereo image acquired by imaging from the reference imaging direction D2 facing the breast M from the front. Even if the image quality of the stereo image acquired by shooting from the shooting directions D1 and D3 is somewhat poor, it does not affect multi-view stereoscopic viewing.

  According to the present embodiment, when performing multi-eye stereo shooting, the radiation dose at the time of shooting from the reference shooting direction D2 facing the breast M from the front among the plurality of reference shooting directions D1 to D3 is determined as another reference shooting direction D1. , The first imaging condition that is larger than the imaging dose at the time of imaging from D3, the grid 24 is used only at the time of imaging from at least one imaging direction at the time of imaging from the reference imaging direction D2 facing the breast M from the front. The radiographic images G2-1 and G2-2 acquired by the imaging conditions 2 and the imaging from the reference imaging direction D2 facing the breast M from the front are acquired by imaging from the other reference imaging directions D1 and D3. The radiographic images G1-1, G1-2, G3-1, G3-2 are obtained by the third imaging condition for lowering the resolution, and the radiography acquired from the imaging from the reference imaging direction D2 facing the breast M from the front. The density resolution of the radiation images G1-1, G1-2, G3-1, and G3-2 acquired by imaging from the other reference imaging directions D1 and D3 is lower than that of the line images G2-1 and G2-2. At least one of the fourth imaging conditions is set.

  Therefore, by setting the first imaging condition, it is possible to reduce the exposure dose to the breast M that is the subject without affecting the stereoscopic view of the multi-view stereo image. In addition, by setting the second imaging condition, the radiation from the scattered radiation is removed by the grid 24 at the time of imaging from the reference imaging direction D2 facing the breast M from the front, while from other reference imaging directions D1 and D3. Since the grid 24 is not used at the time of imaging, there is no need to increase the radiation dose, so that the exposure dose of the breast M can be reduced without affecting the stereoscopic view of the multi-view stereo image.

  Moreover, since the capacity | capacitance of the radiographic images G1-1, G1-2, G3-1, and G3-2 can be reduced by setting the 3rd and 4th imaging conditions, it has influence on the stereoscopic vision of a multi-view stereo image. Without affecting, the total capacity of the radiographic image acquired by multi-eye stereo imaging can be reduced.

  In the above embodiment, there are three reference shooting directions. However, the present invention is not limited to this, and multi-eye stereo shooting may be performed from two or four or more reference shooting directions. Here, when performing multi-view stereo imaging from four or more reference imaging directions, the first imaging condition may be such that the radiation dose is reduced in the reference imaging direction away from the direction facing the breast M from the front. As for the second imaging condition, the grid 24 may be used only when imaging in the standard imaging direction with the breast M facing from the front. With regard to the third and fourth imaging conditions, the resolution and density resolution may be lowered for a radiographic image acquired by imaging from the reference imaging direction away from the direction facing the breast M from the front.

  Moreover, in the said embodiment, although the radiographic imaging apparatus of this invention is set as the apparatus which image | photographs the radiographic image of a breast, it is not restricted to a breast as a subject, For example, the radiographic imaging apparatus which image | photographs a chest, a head, etc. It is also possible to use.

DESCRIPTION OF SYMBOLS 1 Radiation imaging device 2 Computer 2a Control part 2b Radiation image memory | storage part 2c Imaging condition setting part 2d Display control part 3 Monitor 4 Input part 10 Imaging part 13 Arm part 14 Imaging stand 15 Radiation detector 16 Radiation irradiation part 17 Radiation source 18 Compression plate 22 Collimator 24 Grid

Claims (4)

Radiation irradiation means for irradiating the subject with radiation;
Radiation detecting means for detecting the radiation irradiated by the radiation irradiating means and transmitted through the subject and outputting a radiation image of the subject;
In order to acquire a plurality of stereoscopic images of the subject viewed from a plurality of viewpoints, the subject is irradiated with the radiation from two imaging directions having a predetermined convergence angle in each of a plurality of reference imaging directions. Imaging control means for performing multi-view stereoscopic imaging by detecting two radiation images by the radiation detection means;
Of the plurality of reference imaging directions, an imaging condition for making the radiation dose at the time of imaging from a reference imaging direction facing the subject from the front larger than an imaging dose at the time of imaging from another reference imaging direction, Imaging conditions that use a grid only when imaging from at least one imaging direction when imaging from the reference imaging direction facing from the front, and the two radiation images acquired by imaging from the reference imaging direction facing the subject from the front In contrast, the imaging conditions for lowering the resolution of the two radiographic images acquired by imaging from the other reference imaging direction, and the two radiographic images acquired by imaging from the other reference imaging direction On the other hand, at least one of the imaging conditions for lowering the density resolution of the two radiographic images acquired by imaging from the other reference imaging direction. Radiographic imaging apparatus characterized by comprising an imaging condition setting means for setting an imaging condition.   The radiographic image capturing apparatus according to claim 1, further comprising display means for displaying a multi-view stereoscopic image based on the two radiographic images acquired in each of the plurality of reference imaging directions.   The display means displays a stereoscopic image acquired by imaging from the other reference imaging direction around the stereoscopic image acquired by imaging from the reference imaging direction facing the subject from the front. The radiographic image capturing apparatus according to claim 2, wherein: Radiation irradiation means for irradiating the subject with radiation;
An imaging method in a radiographic imaging apparatus, comprising: a radiation detection unit that detects radiation that has been irradiated by the radiation irradiation unit and transmitted through the subject, and outputs a radiation image of the subject,
In order to acquire a plurality of stereoscopic images of the subject viewed from a plurality of viewpoints, the subject is irradiated with the radiation from two imaging directions having a predetermined convergence angle in each of a plurality of reference imaging directions. When performing multi-view stereoscopic imaging by detecting two radiation images by the radiation detection means,
Of the plurality of reference imaging directions, an imaging condition for making the radiation dose at the time of imaging from a reference imaging direction facing the subject from the front larger than an imaging dose at the time of imaging from another reference imaging direction, Imaging conditions that use a grid only when imaging from at least one imaging direction when imaging from the reference imaging direction facing from the front, and the two radiation images acquired by imaging from the reference imaging direction facing the subject from the front In contrast, the imaging conditions for lowering the resolution of the two radiographic images acquired by imaging from the other reference imaging direction, and the two radiographic images acquired by imaging from the other reference imaging direction On the other hand, at least one of the imaging conditions for lowering the density resolution of the two radiographic images acquired by imaging from the other reference imaging direction. Radiation image capturing method characterized by setting the imaging conditions.

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