JP2012175996A - Radiographic imaging method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the impact of radiation vignetting due to a grid, and prevent the occurrence of a situation in which it is not possible to carry out stereoscopic and diagnostic imaging properly due to the excessive impact of scattered radiation, in a radiographic imaging method and device in which stereoscopy is carried out using a grid.SOLUTION: Thickness information of a subject M is acquired, and if the thickness information does not exceed a specified threshold, imaging is carried out using a grid 30 in one imaging direction among two imaging directions, and without using the grid 30 in the other imaging direction. If the thickness information exceeds the specified threshold, imaging is carried out using the grid 30 in the two imaging directions.

Description

  The present invention relates to a radiographic imaging method and apparatus for irradiating a subject with radiation from a plurality of different imaging directions and detecting a radiographic image for each imaging direction, and in particular, a grid for removing scattered rays caused by the subject. The present invention relates to a radiographic image capturing method and apparatus for performing image capturing using a camera.

  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, in general, in a radiographic imaging apparatus, in order to prevent scattered radiation scattered in a subject from entering the radiation image detector, in order to remove the scattered radiation on the detection surface side of the radiation image detector. The grid is arranged.

  Such a problem of scattered radiation is the same in a radiographic imaging apparatus that captures a stereoscopic image. For example, Patent Document 1 proposes a radiographic imaging apparatus that performs stereo imaging using a grid. Yes.

  And in patent document 1, when performing a stereo imaging | photography using a grid, for example, when an imaging angle exceeds 10 degrees, the radiation dose which reaches | attains a radiographic image detector by the eclipse of the radiation in a grid reduces. In view of this, it has been proposed to take a picture without using a grid.

JP 2010-233858 A

  However, if the subject is photographed without using the grid as in Patent Document 1 until the subject is relatively thick, the influence of scattered radiation becomes large and the sharpness is greatly reduced, so that a stereoscopic view is obtained. As for one of the two radiographic images, information in the subject is almost lost, and there is a problem that appropriate stereoscopic vision and image diagnosis cannot be performed.

  In view of the above circumstances, the present invention can reduce the influence of vignetting caused by the grid as described above, and the influence of scattered radiation becomes excessive, so that stereoscopic viewing and image diagnosis cannot be performed appropriately. An object of the present invention is to provide a radiographic imaging method and apparatus capable of preventing the situation from occurring.

  The radiographic image capturing apparatus of the present invention includes a radiation irradiating unit that irradiates a subject with radiation from two different imaging directions, and a radiographic image that detects a radiographic image for each imaging direction by irradiation of radiation from the radiation irradiating unit. In a radiographic imaging apparatus comprising a detector and provided with a grid for removing scattered radiation generated by the subject between the subject and the radiographic image detector, a thickness information acquisition unit that acquires thickness information of the subject When the thickness information is within a predetermined threshold, shooting is performed using a grid for one of the two shooting directions, and shooting is performed without using the grid for the other shooting direction. If the thickness information is larger than a predetermined threshold value, shooting is performed using a grid in two shooting directions. .

  In the radiographic imaging device of the present invention, when the thickness information is within a predetermined threshold, the larger one of the two imaging directions and the angle formed by the perpendicular of the detection surface of the radiographic image detector is larger. The shooting direction can be taken without using a grid.

  In addition, when the thickness information is within a predetermined threshold, the radiation source is controlled so that the radiation dose at the time of imaging without using the grid is lower than the radiation dose at the time of imaging using the grid. A control unit can be provided.

  Further, a moving mechanism for moving the grid can be provided.

  In addition, the subject is a breast, a compression plate that compresses the breast is provided, and the thickness information acquisition unit acquires thickness information based on the position information of the compression plate.

  In addition, a selection instruction receiving unit that receives a selection instruction as to whether or not to perform shooting without using a grid is provided, and an instruction to perform shooting without using a grid is received by the selection instruction receiving unit, and thickness information Can be taken without using the grid for the other shooting direction.

  The radiographic image capturing method of the present invention is a radiographic image capturing method in which a subject is irradiated with radiation from two different imaging directions, and a radiographic image for each imaging direction is detected by a radiation image detector. In a radiographic image capturing method for capturing a radiographic image by providing a grid for removing scattered radiation from the subject between the subject and the radiographic image detector, the thickness information of the subject is acquired, and the thickness information is If it is within the predetermined threshold, shooting is performed using the grid for one of the two shooting directions, and shooting is performed without using the grid for the other shooting direction. When is larger than a predetermined threshold, shooting is performed using a grid in two shooting directions.

  According to the radiographic imaging method and apparatus of the present invention, when thickness information of a subject is acquired and the thickness information is within a predetermined threshold, one imaging direction of two imaging directions is obtained. While taking a picture using a grid and taking a picture without using a grid for the other picture taking direction, it is possible to prevent a reduction in radiation dose due to grid vignetting for the other picture taking direction. Since the thickness of the subject is not large, it is possible to prevent a situation in which the effect of scattered radiation becomes excessive and stereoscopic viewing and image diagnosis are not properly performed. At this time, the radiographic image captured in the other imaging direction is affected by some scattered radiation. However, in the stereoscopic view in which two radiographic images are observed at the same time, of the two radiographic images, Even if the image quality of only one radiographic image is somewhat lowered, it is considered that an appropriate stereoscopic image can be observed if the image quality of the other radiographic image is good.

  When the thickness information is larger than a predetermined threshold, shooting is performed using the grid in the two shooting directions. Therefore, when the subject is thick, the influence of scattered radiation becomes excessive, and stereoscopic vision and image It is possible to prevent a situation in which diagnosis cannot be performed properly.

  Furthermore, in the radiographic image capturing method and apparatus of the present invention, when the thickness information is within a predetermined threshold value, imaging is performed without using the grid as described above, so the radiation dose at the time of imaging using the grid As a result, the radiation dose at the time of imaging without using the grid can be made lower, and thereby the exposure dose of the subject can be reduced.

  Further, in the radiographic image capturing method and apparatus according to the present invention, a selection instruction as to whether or not to perform imaging without using a grid is received, and an instruction to perform imaging without using a grid is received, and thickness information is received. When the image is within a predetermined threshold and the shooting is performed without using the grid for the other shooting direction, the photographer can arbitrarily select whether to perform shooting without using the grid. Therefore, it is possible to perform shooting according to the purpose and the photographer's request.

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 state which moved the radiation source unit in the mammography imaging 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.

  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. FIG. 2 shows the arm 13 viewed from the right direction in FIG.

  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 movement of the arm unit 13 in the vertical direction is controlled by an arm controller 31 incorporated in the base 11.

  Inside the imaging table 14, a radiographic image detector 15 such as a flat panel detector, a grid 30 for removing scattered radiation generated when the breast is irradiated with radiation, and a charge from the radiographic image detector 15. A detector controller 33 is provided for controlling signal readout and the like.

  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.

  As described above, the grid 30 is for removing scattered radiation, and is formed by alternately arranging a member that absorbs radiation and a member that transmits radiation in a striped or lattice shape. Is.

  Further, a grid moving mechanism (not shown in FIG. 1) for moving the grid 30 in the direction of arrow A shown in FIG. The grid moving mechanism moves the grid 30 to the position indicated by the solid line in FIG. 1 when performing imaging using the grid 30, and indicates the position indicated by the dotted line in FIG. 1 when performing imaging without using the grid 30. The grid 30 is moved. It is assumed that the arm 13 is provided with a predetermined space so that the grid 30 can be retracted at a position indicated by a dotted line in FIG. A known actuator can be used as the grid moving mechanism. A method for controlling the grid moving mechanism will be described in detail later.

  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.

  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 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 40, the radiation image storage unit 41, and the display as shown in FIG. A control unit 42 and a thickness information acquisition 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 display control unit 42 performs predetermined signal processing on the radiographic image signal read from the radiographic image storage unit 41, and then displays a breast stereo image on the monitor 3.

  The thickness information acquisition unit 43 is installed on the imaging table 14 and acquires the thickness information of the breast of the subject M in a state of being compressed by the compression plate 18. The thickness information in the present embodiment is information indicating the thickness of the breast in the direction perpendicular to the breast installation surface. The breast thickness information may be set and input by the photographer using the input unit 4, or the position information of the compression plate 18 is acquired from the compression plate controller 34, and based on the position information of the compression plate 18. Thus, the thickness information may be acquired. When the photographer makes a setting input using the input unit 4, a gauge may be provided on the arm unit 13 so that the photographer can check the thickness of the breast.

  The grid moving mechanism 35 shown in FIG. 3 is provided in the imaging table 14 shown in FIG. 1 as described above, and moves the grid 30 based on the control signal output from the control unit 40 of the computer 2. It is something to be made.

  The input unit 4 is configured by a pointing device such as a keyboard and a mouse, for example, and receives input by a photographer such as predetermined imaging conditions and breast thickness information described above.

  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 mammography / display system of this embodiment will be described with reference to the flowchart shown in FIG.

  First, the breast of the subject M is placed on the imaging table 14, and the breast is compressed by the compression plate 18 with a predetermined pressure (S10). Next, the thickness information acquisition unit 43 acquires breast thickness information (S12).

  Then, when an imaging start instruction is input by the photographer, the first radiographic image of the two radiographic images constituting the stereo image is captured (S14).

  Specifically, first, the control unit 40 reads a preset shooting angle θ for shooting a stereo image, and outputs information on the read shooting angle θ to the arm controller 31. In the present embodiment, θ = 0 ° and θ = 4 ° are stored in advance as information on the shooting angle θ. However, the present invention is not limited to this. Can be set.

  Then, the arm controller 31 receives the information of the shooting angles θ = 0 ° and θ = 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 θ = 0 °, a control signal is output so that the arm unit 13 is perpendicular to the imaging table 14 as shown in FIG.

  At this time, the control unit 40 sends a control signal to the grid moving mechanism 35 when the grid 30 is not arranged at the position (the position indicated by the solid line in FIG. 1) when photographing using the grid 30. The grid 30 is moved to the position where the image is output and shooting is performed using the grid.

  Then, in a state where the arm unit 13 is in a direction perpendicular to the imaging table 14 according to the control signal output from the arm controller 31, the control unit 40 notifies the radiation source controller 32 and the detector controller 33. On the other hand, a control signal is output so as to perform radiation irradiation and readout of a radiographic image signal. In response to this control signal, radiation is emitted from the radiation source 17, and the radiation passes through the grid 30 and is then applied to the breast. A radiographic image obtained by photographing the breast from 0 ° direction is detected by the radiographic image detector 15, the radiographic image signal is read by the detector controller 33, and predetermined signal processing is performed on the radiographic image signal. Then, it is memorize | stored in the radiographic image storage part 41 of the computer 2 (S16).

  Subsequently, the control unit 40 captures a radiographic image at an imaging angle θ = 4 °. At this time, the control unit 40 sets the thickness information acquired by the thickness information acquisition unit 43 in S12 in advance. It is determined whether it is within the threshold value (S18). And when the thickness information acquired by the thickness information acquisition part 43 is less than a threshold value (S18, YES), the control part 40 outputs a control signal to the grid movement mechanism 35, and shows the dotted line shown in FIG. The grid 30 is moved to a position and saved (S20). The threshold value can be set to, for example, about 2 cm to 3 cm, but can be arbitrarily set using the input unit 4 according to the allowable reduction in sharpness due to the influence of scattered rays.

  On the other hand, when the thickness information acquired by the thickness information acquisition unit 43 is larger than the threshold (S18, NO), the control unit 40 uses the position as it is, that is, the grid 30 without moving the grid 30. The position in the case of performing shooting is kept (S22).

  Then, as described above, the control unit 40 arranges the grid 30 based on the breast thickness information, and then captures a radiographic image at an imaging angle θ = 4 ° (S24).

  Specifically, according to the control signal output from the control unit 40, the arm controller 31 controls the arm unit 13 to rotate + θ ° with respect to the direction perpendicular to the imaging table 14, as shown in FIG. Is output. That is, in the present embodiment, the control signal is output so that the arm unit 13 is rotated by 4 ° with respect to the direction perpendicular to the imaging table 14.

  Then, in a state where the arm unit 13 is 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 outputs the radiation image signal. A control signal is output for reading. In response to this control signal, radiation is emitted from the radiation source 17, a radiation image obtained by photographing the breast from the 4 ° direction is detected by the radiation image detector 15, and the radiation image signal is read by the detector controller 33. After the predetermined signal processing is performed, the signal is stored in the radiation image storage unit 41 of the computer 2 (S26).

  Then, the two radiographic image signals stored in the radiographic image storage unit 41 are read by the display control unit 42, and after the predetermined processing is performed on these radiographic image signals in the display control unit 42, 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 (S28).

  According to the breast image radiographing display system of the above-described embodiment, when the breast thickness information is acquired and the thickness information is within a predetermined threshold, the radiographing angle θ = 0 ° between the two radiographing angles. Since the image is taken using the grid 30 and the image is taken without using the grid 30 for the image angle θ = 4 °, the radiation due to the vignetting of the grid 30 is used for the image with the image angle θ = 4 °. In addition to preventing the radiation dose from being reduced, the thickness of the subject is not large, so that it is possible to prevent the situation where the effect of scattered radiation becomes excessive and stereoscopic viewing and image diagnosis are not properly performed. .

  When the thickness information is larger than a predetermined threshold, the grid 30 is used for shooting at two shooting angles. Therefore, when the subject is thick, the influence of scattered rays becomes excessive and stereoscopic viewing or It is possible to prevent a situation in which image diagnosis cannot be performed appropriately.

  In the above embodiment, the grid 30 is not used for imaging at an imaging angle θ = 4 ° when the breast thickness information is within a predetermined threshold, but at this time, the imaging angle θ = 0 °. The control unit 40 controls the radiation source 17 so that the radiation dose at the imaging angle θ = 4 ° without using the grid 30 is lower than the radiation dose at the time of imaging. Also good. That is, when the grid 30 is not used, it is not necessary to consider the reduction in the radiation dose due to the radiation vignetting in the grid 30, so that the radiation dose emitted from the radiation source 17 can be lowered by that amount. The exposure amount of the subject M can be reduced.

  Specifically, for example, when the transmittance of the radiation of the breast is 1/20 and the transmittance of the grid 30 is 1/2, in order to reach the radiation image detector 15 with 10 mR of radiation, the grid 30 is In the case of photographing using 400 mR of radiation from the radiation source 17, it is not necessary to consider the transmittance of the grid 30 in photographing without using the grid 30. Is emitted from the radiation source 17. Therefore, the exposure dose of the subject can be halved at this time.

  In the above-described embodiment, the presence / absence of the grid 30 is determined based on only the breast thickness information for imaging at an imaging angle θ = 4 °. When the input unit 4 accepts the selection instruction, and the input unit 4 accepts an instruction to perform imaging without using the grid 30, and the breast thickness information is within a threshold value, the imaging is performed. You may make it perform imaging | photography which does not use the grid 30 about angle (theta) = 4 degrees. When the input unit 4 receives an instruction not to perform imaging without using the grid 30, even when the breast thickness information is within the threshold value, imaging is performed for the imaging angle θ = 4 °. As with the shooting at the angle θ = 0 °, the shooting using the grid 30 may be performed.

  Further, in the above-described embodiment, imaging is performed for the imaging angle θ = 0 ° and the imaging angle θ = 4 °, and the imaging is performed without using the grid 30 based on the breast thickness information for the imaging angle θ = 4 °. For example, when different imaging angles are adopted as the two imaging angles, the larger one of the two imaging angles formed by the perpendicular to the detection surface of the radiation image detector 15 is used. It is desirable to perform imaging without using the grid 30 based on breast thickness information regarding the imaging angle. The two shooting angles may be the same shooting angle, for example, ± 2 °. In this case, which shooting angle is used for shooting with a low dose without using the grid 30. You may make it carry out.

  In the above embodiment, the imaging target is the breast. However, the imaging target of the radiographic imaging device of the present invention is not limited to the breast. For example, a part such as a hand that is relatively thin and hardly affected by scattered radiation. May be the subject of shooting.

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 board 30 Grid 35 Grid moving mechanism 40 Control part 41 Radiation Image storage unit 42 Display control unit 43 Thickness information acquisition unit

Claims (7)

A radiation irradiating unit that irradiates radiation from two different imaging directions with respect to the subject; and a radiation image detector that respectively detects a radiation image for each imaging direction by irradiation of the radiation of the radiation irradiating unit, In a radiographic imaging apparatus provided with a grid for removing scattered radiation generated by the subject between the subject and the radiographic image detector,
A thickness information acquisition unit for acquiring thickness information of the subject;
When the thickness information is within a predetermined threshold, shooting is performed using the grid for one shooting direction of the two shooting directions, and the grid is not used for the other shooting direction. Take a photo at
When the thickness information is larger than the predetermined threshold value, the radiographic image capturing apparatus is configured to perform imaging using the grid in the two imaging directions.   When the thickness information is within a predetermined threshold value, an image is taken without using the grid for an image taking direction having a larger angle formed with a perpendicular to the detection surface of the radiation image detector among the two image taking directions. The radiographic image capturing apparatus according to claim 1, wherein:   When the thickness information is within a predetermined threshold, the radiation source is such that the dose of the radiation at the time of imaging without using the grid is lower than the dose of the radiation at the time of imaging using the grid. The radiographic imaging apparatus according to claim 1, further comprising a control unit that controls   The radiographic imaging apparatus according to any one of claims 1 to 3, further comprising a moving mechanism for moving the grid. The subject is a breast, and includes a compression plate that compresses the breast,
The radiographic image capturing apparatus according to claim 1, wherein the thickness information acquisition unit acquires the thickness information based on position information of the compression plate. A selection instruction receiving unit that receives a selection instruction as to whether to perform shooting without using the grid;
When the selection instruction receiving unit receives an instruction to perform imaging without using the grid, and the thickness information is within a predetermined threshold, the grid is used for the other imaging direction. The radiographic image capturing apparatus according to claim 1, wherein the radiographic image capturing apparatus performs non-capturing imaging. A radiographic imaging method for irradiating a subject with radiation from two different imaging directions, and detecting a radiographic image for each of the imaging directions with a radiation image detector by irradiation of the radiation, In a radiographic image capturing method for capturing the radiographic image by providing a grid for removing scattered radiation due to the subject between the radiographic image detector,
Obtaining thickness information of the subject,
When the thickness information is within a predetermined threshold value, shooting is performed using the grid for one of the two shooting directions, and the grid is used for the other shooting direction. Shoot without using it,
When the thickness information is larger than the predetermined threshold value, the radiographic image capturing method is characterized by performing imaging using the grid in the two imaging directions.

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