JP2018175320A - Radiography system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately reduce an influence of a subcutaneous soft tissue in a radiation image.SOLUTION: A radiography system 100 causes a first image acquisition device 1 to apply radiation to a subject H and dynamically capture an image thereof to acquire a dynamic image of the subject H, and, at same timing as that of imaging of each frame image of the dynamic image, causes a second image acquisition device 2 to capture an image of a lateral face of the subject H. A console 3 specifies a position and thickness of a subcutaneous soft tissue of the subject H on the basis of the image acquired by the second image acquisition device 2, estimates a radiation attenuation amount by the subcutaneous soft tissue at each pixel of each frame image of the dynamic image on the basis of the specified position and thickness of the subcutaneous soft tissue, and corrects each frame image of the dynamic image on the basis of the estimated radiation attenuation amount.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a radiation imaging system.

  In recent years, it has been proposed to use a dynamic image obtained by radiography of the chest movement from the front or the back for diagnosis. However, in the chest, bones such as sternum and clavicle and soft tissue are mixed, and there is a problem that it is difficult to use for image diagnosis.

  Therefore, for example, in Patent Document 1, for each of a plurality of frame images constituting a dynamic image, a first frame consisting of a bone shadow image excluding soft tissue shadow and a second frame consisting of a soft tissue image excluding bone shadow are described. It is described to generate and generate an X-ray motion image of bone shadow and / or an X-ray motion image of soft tissue from an original X-ray motion image.

JP, 2015-43894, A

  By the way, as shown by a broken line in FIG. 8 in the dynamic image of the chest, subcutaneous soft tissues such as the breast and subcutaneous fat are reflected, and the lung field is observed or analyzed using the dynamic image using radiation. In these cases, these subcutaneous soft tissues are an inhibiting factor.

  However, Patent Document 1 does not describe taking into consideration the influence of subcutaneous soft tissue when observing lung dynamics associated with respiration. Further, in the technology described in Patent Document 1, the structure other than the lung field is recognized from the original X-ray moving image itself, and the influence of the structure other than the lung field can not be recognized with high accuracy.

  An object of the present invention is to accurately reduce the influence of subcutaneous soft tissue in a radiation image.

In order to solve the above-mentioned subject, the radiography system of the invention according to claim 1 is
A first image acquisition unit configured to acquire a radiation image of the living body by irradiating the living body with radiation and capturing the radiation;
A second image acquisition unit that acquires an image obtained by capturing the subcutaneous soft tissue of the living body by imaging the living body from a direction different from that of the first image acquisition unit;
The position and thickness of the subcutaneous soft tissue of the living body included in the radiation image are specified based on the image acquired by the second image acquisition unit, and the position and thickness of the subcutaneous soft tissue of the living body specified are specified. Estimation means for estimating the radiation attenuation amount by the subcutaneous soft tissue at each pixel of the radiation image;
A correction unit configured to correct the radiation image based on the radiation attenuation amount estimated by the estimation unit;
Equipped with

In the invention described in claim 2, in the invention described in claim 1,
The second image acquisition unit images the living body from a direction different from the first image acquisition unit by a visible light camera, an infrared sensor, a microwave sensor, an ultrasonic sensor, or a radar sensor.

The invention described in claim 3 is the invention described in claim 2
The first image acquisition means acquires a radiation image of the front of the living body,
The second image acquisition unit acquires an image of the side surface of the living body.

In the invention according to claim 4, in the invention according to claim 3,
The second image acquisition means converts and acquires an image obtained by photographing the side of the living body with the visible light camera into an image showing only a silhouette or an outline of the side of the living body.

In the invention according to claim 5, in the invention according to claim 3,
The second image acquisition unit captures, with the visible light camera, a shadow of the side surface of the living body obtained by irradiating light from the light source to the side surface of the living body, and acquires an image of the shadow of the side surface of the living body .

In the invention according to claim 6, in the invention according to claim 1,
The second image acquisition means radiographs the living body from a direction different from that of the first image acquisition means, and the obtained radiation image and the radiation image obtained by the first image acquisition means Based on the three-dimensional image capturing the subcutaneous soft tissue of the living body.

In the invention according to claim 7, in the invention according to any one of claims 1 to 6,
The first image acquisition unit acquires a plurality of frame images indicating the movement of the living body by dynamic imaging.
The second image acquisition unit captures a plurality of the images by capturing the living body at the same timing as each of the plurality of frame images captured by the first image acquisition unit.
The estimation unit is a position of subcutaneous soft tissue of the living body included in each frame image acquired by the first image acquisition unit based on the images acquired at the same timing by the second image acquisition unit. Identify the thickness.

In the invention according to claim 8, in the invention according to any one of claims 1 to 6,
The first image acquisition unit acquires a plurality of frame images indicating the movement of the living body by dynamic imaging.
The second image acquisition unit captures the image of the living body at the same timing as any one of the plurality of frame images by the first image acquisition unit, and acquires the image.
The estimation means detects the position of the feature point of the subcutaneous soft tissue of the living body from each of the plurality of frame images, and the position of the feature point detected in each of the frame images and the second image acquisition means The difference between the timing at which the image is acquired and the position of the feature point detected in the frame image acquired at the same timing as the timing at which each frame image is acquired and the image acquisition by the second image acquisition means Position and thickness of the subcutaneous soft tissue of the living body which is calculated based on the image acquired by the second image acquiring means, calculated as the movement amount of the feature point between The position and thickness of the subcutaneous soft tissue of the living body included in each frame image are specified based on the movement amount calculated for.

In the invention according to claim 9, in the invention according to any one of claims 1 to 6,
The first image acquisition unit acquires a plurality of frame images indicating the movement of the living body by dynamic imaging.
The second image acquisition unit captures the image of the living body at the same timing as any one of the plurality of frame images by the first image acquisition unit, and acquires the image.
The estimation unit detects a predetermined structure from each of the plurality of frame images, and the image is acquired by the position of the predetermined structure detected in each of the frame images and the second image acquisition unit. The timing at which each frame image is acquired and the timing at which the image is acquired by the second image acquisition means are the difference from the position of the predetermined structure detected in the frame image acquired at the same timing as the timing Of the position and thickness of the subcutaneous soft tissue of the living body which is calculated based on the image acquired by the second image acquiring means and calculated as the amount of movement of the predetermined structure between The position and thickness of the subcutaneous soft tissue of the living body included in each frame image are specified based on the calculated movement amount.

  According to the present invention, it is possible to accurately reduce the influence of subcutaneous soft tissue in a radiation image.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the whole structure of the radiation imaging system which concerns on this embodiment. It is a figure which shows typically imaging | photography by the 1st image acquisition apparatus of FIG. It is a block which shows the functional structure of the console of FIG. It is a flowchart which shows the image acquisition process A performed by the control part of FIG. It is a flowchart which shows the subcutaneous soft-tissue removal process A performed in step S3 of FIG. It is a flowchart which shows the image acquisition process B performed by the control part of FIG. It is a flowchart which shows the subcutaneous soft-tissue removal process B performed in FIG.6 S13. It is a figure which shows an example of the dynamic image of a chest.

  Hereinafter, preferred embodiments according to the present invention will be described with reference to the drawings. The present invention is not limited to the illustrated example.

First Embodiment
(Configuration of radiation imaging system 100)
First, the configuration of the first embodiment according to the present invention will be described.
FIG. 1 shows an example of the overall configuration of a radiation imaging system 100 according to the present embodiment.
As shown in FIG. 1, a radiation imaging system 100 includes a first image acquisition device 1, a second image acquisition device 2, and a console 3. The console 3 is communicably connectable to the first image acquisition device 1 and the second image acquisition device via a communication network such as a LAN (Local Area Network).

(First image acquisition device 1)
The first image acquisition device 1 is a device that performs dynamic imaging on a subject H.
With dynamic imaging, radiation such as X-rays is applied in pulses to the object H repeatedly at predetermined time intervals (pulse irradiation), or continuously at a low dose rate without interruption (continuous irradiation) ) Means to acquire multiple images. In the dynamic imaging, for example, the dynamic of the subject H having a cycle (cycle) such as a change in form of expansion and contraction of the lung accompanying respiratory movement, a pulse of the heart and the like is taken. A series of images obtained by this continuous imaging is called a dynamic image. Further, each of a plurality of images constituting a dynamic image is called a frame image.
In the present embodiment, the radiation imaging system 100 will be described as imaging the movement of the chest with the subject H as the chest.

FIG. 2 shows a schematic configuration of the first image acquisition device 1. As shown in FIG. 2, the first image acquisition device 1 is configured to include a radiation source 11, an imaging control unit 12, an exposure switch 13, a radiation detection unit 14, a communication unit 15, and the like. The radiation source 11 and the radiation detection unit 14 are disposed across the subject H in the front-rear direction of the subject H, and acquire a dynamic image of the front of the chest of the subject H.
In the following description, the radiation irradiation direction of the radiation source 11 is the z direction, the vertical direction (vertical direction) is the y direction, and the direction orthogonal to the z direction and the y direction is the x direction.

  The radiation source 11 emits radiation (X-ray) to the subject H according to the control of the imaging control unit 12.

  The imaging control unit 12 controls the radiation source 11 and the radiation detection unit 14 based on the imaging conditions transmitted from the console 3 to perform radiation imaging. The shooting conditions input from the console 3 are, for example, tube current, tube voltage, frame rate (number of frame images shot per unit time (1 second)), total shooting time per shot or total number of shot frame images The additional filter type, the image size (matrix size), and in the case of pulse irradiation, the irradiation time per frame image, and the like.

  The radiation switch 13 inputs a radiation irradiation instruction signal to the console 3 by being pressed.

  The radiation detection unit 14 is a portable radiation detector (FPD: Flat Panel Detector) compatible with dynamic imaging. The radiation detection unit 14 detects radiation that has been emitted from the radiation source 11 and transmitted through at least the subject H at a predetermined position on a substrate such as a glass substrate according to its intensity, and converts the detected radiation into an electrical signal A plurality of radiation detection elements to be stored are arranged in a matrix (two-dimensional). For example, a switching unit such as a thin film transistor (TFT) is connected to each radiation detection element, and accumulation and reading of an electrical signal to each radiation detection element are controlled by control of the switching unit by the imaging control unit 12. (Frame image) is acquired. FPDs include an indirect conversion type in which radiation is converted into an electrical signal by a photoelectric conversion element through a scintillator, and a direct conversion type in which radiation is directly converted into an electrical signal, any of which may be used.

  The communication unit 15 includes a LAN adapter and the like, and controls data transmission and reception with an external device such as the console 3 connected to a communication network N such as a LAN.

(Second image acquisition device 2)
The second image acquisition device 2 is a device that images the subject H from a direction different from that of the first image acquisition device 1 and acquires an image capturing a breast of the subject H and subcutaneous soft tissue such as subcutaneous fat.
As the second image acquisition device 2, for example, a sensor for acquiring an image of the side surface of the subject H (image taken from the x direction), for example, a visible light camera, an infrared sensor, a microwave sensor, an ultrasonic sensor, a radar sensor Etc. can be used. The second image acquisition device 2 is arranged such that the range in the y direction of the image to be acquired is the same as the range in the y direction of the image acquired by the first image acquisition device 1.
The second image acquisition device 2 acquires a side image obtained by photographing the subject H from the side based on the control from the console 3, and transmits the side image to the console 3.

(Console 3)
The console 3 controls an operation of acquiring a dynamic image of the subject H by the first image acquisition device 1 and an operation of acquiring a side image of the object H by the second image acquisition device 2. In addition, the console 3 specifies the position and thickness of the subcutaneous soft tissue of the subject H in each frame image of the dynamic image based on the side image acquired by the second image acquisition device 2, and specifies the specified position and thickness. Based on each frame image of the dynamic image, correction is performed to remove the influence of the subcutaneous soft tissue.

  FIG. 3 shows an example of the functional configuration of the console 3. As shown in FIG. 3, the console 3 includes a control unit 31, a storage unit 32, an operation unit 33, a display unit 34, a communication unit 35 and the like, and the units are connected by a bus 36.

The control unit 31 includes a central processing unit (CPU) and a random access memory (RAM).
And so on. The CPU of the control unit 31 reads out the system program and various processing programs stored in the storage unit 32 according to the operation of the operation unit 33, expands them in the RAM, and operates the respective parts of the console 3 according to the expanded program. And centrally control the operations of the first image acquisition device 1 and the second image acquisition device 2. Further, the control unit 31 executes various processes including an image acquisition process A to be described later according to the expanded program, and functions as an estimation unit and a correction unit.

The storage unit 32 is configured by a non-volatile semiconductor memory, a hard disk or the like. The storage unit 32 stores data such as parameters necessary for execution of processing according to various programs or programs executed by the control unit 31 or processing results. For example, the storage unit 32 stores a program for executing the image acquisition process A shown in FIG. The various programs are stored in the form of readable program code, and the control unit 31 sequentially executes operations according to the program code.
The storage unit 32 also stores imaging conditions at the time of dynamic imaging in the first image acquisition device 1. The photographing conditions can be set by the user by the operation of the operation unit 33.

Also, the storage unit 32, the correction coefficient used in removing the effects of subcutaneous soft tissue from dynamic images (attenuation coefficient) mu ^v are stored. The correction coefficient μ ^v is obtained by the following steps (1) to (4).
(1) the length of the first radiation source 11 of the image acquisition apparatus 1 and the radiation detecting section 14 as a standard SID (L _SID0), fat thickness L _OBJ0 between radiation source 11 and the radiation detecting section 14 (or its Equivalent product). At this time, the fat is placed so as to cover a part of the radiation field (for photographing the air part and the fat part).
(2) The radiation detection unit 14 reads an image by irradiating radiation from the radiation source 11 at a mAs value = mAs ₀ at a tube voltage V (for example, 40 kV to 120 kV in 10 kV increments) that can be used for imaging. Note that the setting as to whether or not to perform binning processing or the like in the radiation detection unit 14 is the same as at the time of shooting of the actual dynamic image.
(3) A representative value (for example, an average value, a median value, a maximum value, a minimum value, etc.) of pixel values (signal values) of a portion where fat of the acquired image is taken is P ^v _obj0 , and other fats _Let P ^v _{air 0} be a representative value of pixel values in a portion where the image is not captured.
(4) The correction coefficient μ ^v is determined by the following (Equation 1). The correction coefficient μ ^v is calculated for each value of the tube voltage V.
μ ^v = P ^v _{air 0} −P ^v _{obj 0} (Expression 1)
The storage unit 32 stores the values of mAs ₀ , L _SID0 , and L _obj0 described above, together with the correction coefficient μ ^v .

  In addition, the storage unit 32 associates the corrected image obtained by performing the correction for removing the influence of the subcutaneous soft tissue on the dynamic image transmitted from the first image acquisition device 1 in association with the patient information of the subject H, examination information, etc. Remember. Patient information includes patient ID, patient's name, age, gender and the like. The examination information includes the examination ID, the examination date, the examination site (here, the front of the chest), and the like.

  The operation unit 33 includes a keyboard having cursor keys, numeric input keys, various function keys and the like, and a pointing device such as a mouse, and controls a command signal input by key operation on the keyboard or mouse operation. Output to 31 In addition, the operation unit 33 may include a touch panel on the display screen of the display unit 34. In this case, the operation unit 33 outputs an instruction signal input via the touch panel to the control unit 31.

  The display unit 34 is configured by a monitor such as an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube), and displays an input instruction or data from the operation unit 33 according to an instruction of a display signal input from the control unit 31. Do.

  The communication unit 35 includes a LAN adapter and the like, and controls data transmission / reception with external devices such as the first image acquisition device 1 and the second image acquisition device 2 connected to a communication network N such as a LAN. Do.

(Operation of radiation imaging system 100)
Next, the operation of the radiation imaging system 100 will be described.
FIG. 4 shows the flow of the image acquisition process A executed by the console 3. The image acquisition processing A is executed by cooperation of the control unit 31 and the program stored in the storage unit 32. Hereinafter, the image acquisition processing A will be described with reference to FIG.

  First, the photographer performs positioning by placing the subject H between the radiation source 11 and the radiation detection unit 14. If the second image acquisition device 2 is a visible light camera, no clothes will be worn, and if it is other than a visible light camera, it will be dressed. Further, it instructs the subject (subject H) a breathing state. For example, it instructs the subject (subject H) to ease and urges resting breathing. If the type of diagnosis target is ventilation, rest breathing may be prompted, and if the type of diagnosis target is blood flow, the subject may be instructed to hold their breath. When the imaging preparation is completed, the exposure switch 13 is pressed to input a radiation irradiation instruction.

  When the exposure switch 13 is pressed and a radiation irradiation instruction is input from the first image acquisition device 1, the control unit 31 transmits an imaging start instruction to the first image acquisition device 1 and starts dynamic imaging. To obtain a plurality of frame images in front of the subject H (step S1). Further, in synchronization with (at the same timing) photographing of each frame image by the first image acquisition device 1, the second image acquisition device 2 is made to acquire the side image (side image) of the subject H (step S2) .

Each frame image of the dynamic image acquired by the first image acquisition device 1 is attached with the image number (number indicating the acquisition order of the image) and the imaging condition (including tube voltage V, mAs value), and the console is sequentially Sent to 3 Each side image acquired by the second image acquisition device 2 is sequentially transmitted to the console 3 with an image number (a number indicating the acquisition order of the images).
When the second image acquisition device 2 is a visible light camera, it is desirable not to visualize an image captured by the visible light camera from the viewpoint of privacy protection. Therefore, in the image processing unit of the second image acquisition device 2, for example, the image acquired by the visible light camera is binarized and converted into an image consisting of only the silhouette or skin line information (outline) of the subject H and the console Send to 3 Alternatively, the second image acquisition device 2 captures a shadow of the side surface of the subject H obtained by irradiating light from the light source to the side surface of the subject H using a visible light camera and obtains an image of the shadow of the side surface of the subject H And may be sent to the console 3.
When the control unit 31 of the console 3 receives an image from the first image acquisition device 1 and the second image acquisition device 2 by the communication unit 35, each frame image and each side image of the received dynamic image are represented by image numbers. It associates and stores in RAM.

  Next, the control unit 31 executes subcutaneous soft tissue removal processing A on each frame image of the acquired dynamic image using the corresponding (photographed at the same timing) side image (step S3).

  FIG. 5 shows the flow of the subcutaneous soft tissue removing process A performed in step S3 of FIG. The subcutaneous soft tissue removing process A is executed by the cooperation of the control unit 31 and the program stored in the storage unit 32. The subcutaneous soft tissue removing process A will be described below with reference to FIG.

First, the control unit 31 specifies the thickness of the subcutaneous soft tissue at each pixel of the frame image of the dynamic image based on the side image corresponding to the frame image of the dynamic image (photographed at the same timing) (step S31) .
The subcutaneous soft tissue in the chest is approximately the breast, with fat and mammary gland as the main components. By specifying the thickness of the subcutaneous soft tissue (breast) at each pixel of the frame image of the dynamic image, it is possible to specify the transmission distance of radiation at each pixel.

  In step S31, first, a breast lower end line as a feature point of the subcutaneous soft tissue is detected from the side image. The side image is an image representing the shape of the chest viewed from the side, and, for example, a skin line at the boundary between the background and the subject H can be obtained by performing binarization processing. For example, this skin line is tracked from below, and a position where the x coordinate has changed by a predetermined value or more in a predetermined direction is detected as a breast lower end line. Then, edge detection is performed on the frame image of the dynamic image, and the edge where the lower edge line of the breast detected from the side image and the y coordinate are at the same position is the lower edge line of the breast, and the lower edge line of both images matches. Align. Then, for example, the distance between the x-coordinate of the skin line at each y-coordinate in the side image and the x-coordinate of the skin line at the bottom of the breast lower end line is specified as the thickness of subcutaneous soft tissue at each y-coordinate, and this thickness is a dynamic image The thickness of the subcutaneous soft tissue at each pixel of the same y coordinate of the frame image of The position of the pixel where the thickness of the subcutaneous soft tissue is greater than 0 is specified as the position of the subcutaneous soft tissue.

Next, the control unit 31 determines the radiation attenuation amount by the subcutaneous soft tissue at each pixel of the frame image of the dynamic image based on SID (Source to Image Distance), mAs value, and thickness of the subcutaneous soft tissue at the time of dynamic imaging. It estimates (step S32).
SID is the distance from the radiation irradiation port of the radiation source 11 to the radiation detection unit 14. In the present embodiment, the SID is measured in advance and stored in the storage unit 32, but may be measured and acquired by a sensor or the like. The mAs value can be obtained from incidental information of the frame image of the dynamic image.

In step S32, the control unit 31, the correction coefficient corresponding to the voltage V using the storage unit 32 in the photographing mu ^v, L _SID0 a SID during photographing when calculating the correction coefficient mu ^v, the correction coefficient mu ^v L _obj0 , which is the thickness of fat placed at the time of shooting when calculated, is read, SID at the time of shooting is L _SID , mAs value is mAs ₁ , and the thickness obtained in step S31 is L _{obj (x, y)} The radiation attenuation amount μ _xy of (x, y) is calculated by the following (Equation 2). μ _xy represents the signal amount of radiation attenuated by the subcutaneous soft tissue, and is a correction value of the influence of the subcutaneous soft tissue at each pixel.
^{_{μ xy = μ v × (mAs}} 1 × L SID0 2 × L obj (x, y)) / (mAs 0 × L SID 2 × L obj0) ( Equation 2)

Next, the control unit 31 corrects each pixel value of the frame image of the dynamic image using the calculated radiation attenuation amount μ _xy (step S33).
Each pixel value P _2xy after correction can be obtained by the pixel value P _1Xy obtained by photographing the correction value mu _xy by the following (Equation 3).
_{P 2xy = P 1xy + μ xy} ( Equation 3)

  By executing the above-mentioned subcutaneous soft tissue removal processing A for each frame image of the dynamic image, it is possible to correct the signal value attenuated by the subcutaneous soft tissue in each frame image. When the subcutaneous soft tissue removing process A ends, the control unit 31 proceeds to step S4 in FIG.

In step S4 of FIG. 4, the control unit 31 performs kinetic analysis using each frame image of the kinetic image from which the influence of the subcutaneous soft tissue has been removed (step S4). The kinetic analysis may include, for example, inter-frame difference processing in which difference values are calculated between frame images temporally adjacent to each other by applying a high-pass filter or low-pass filter in the time direction to the dynamic image. It is not something to be done.
Then, the result of the kinetic analysis is displayed on the display unit 34 (step S5), and the image acquisition process A is ended.

  As described above, according to the radiation imaging system 100, the radiation attenuation amount by the subcutaneous soft tissue at each pixel of each frame image of the dynamic image acquired by the first image acquisition device 1 is dynamically transmitted by the second image acquisition device 2. The frame image of the dynamic image is corrected based on the estimated radiation attenuation amount estimated using each frame image of the side surface acquired at the same timing as imaging. Therefore, since the radiation attenuation amount can be estimated with high accuracy compared to the case of estimating the radiation attenuation amount by the subcutaneous soft tissue from each frame image of the dynamic image, the influence of the subcutaneous soft tissue can be accurately removed (reduced) Can.

Second Embodiment
Next, a second embodiment of the present invention will be described.
In the first embodiment, an example of specifying the position and thickness of the subcutaneous soft tissue of each frame image of the dynamic image has been described based on each side image acquired at the same timing as each frame image of the dynamic image. In the second embodiment, an example will be described in which the position and thickness of the subcutaneous soft tissue in each frame image of the dynamic image are specified from one side image.

  In the second embodiment, the storage unit 32 of the console 3 stores a program for executing the image acquisition process B shown in FIG. The other configuration is the same as that described in the first embodiment, and therefore the description will be used. The operation of the second embodiment will be described below.

  FIG. 6 shows the flow of the image acquisition process B executed by the console 3. The image acquisition processing B is executed by the cooperation of the control unit 31 and the program stored in the storage unit 32. Hereinafter, the image acquisition processing B will be described with reference to FIG.

  First, the photographer performs positioning by placing the subject H between the radiation source 11 and the radiation detection unit 14. If the second image acquisition device 2 is a visible light camera, no clothes will be worn, and if it is other than a visible light camera, it will be dressed. Further, it instructs the subject (subject H) a breathing state. For example, it instructs the subject (subject H) to ease and urges resting breathing. If the type of diagnosis target is ventilation, rest breathing may be prompted, and if the type of diagnosis target is blood flow, the subject may be instructed to hold their breath. When the imaging preparation is completed, the exposure switch 13 is pressed to input a radiation irradiation instruction.

  When the exposure switch 13 is pressed and a radiation irradiation instruction is input from the first image acquisition device 1, the control unit 31 transmits an imaging start instruction to the first image acquisition device 1 and starts dynamic imaging. To obtain a plurality of frame images (step S11). Further, in synchronization with (at the same timing) photographing of any one frame image by the first image acquisition device 1, the second image acquisition device 2 acquires one side image (step S12).

The side image acquired by the second image acquisition device 2 is transmitted to the console 3. In addition, each frame image of the dynamic image acquired by the first image acquisition device 1 is accompanied by an image number (number indicating the acquisition order of the images) and imaging conditions (including tube voltage V and mAs values). Are sent to the console 3 sequentially.
When the second image acquisition device 2 is a visible light camera, the image processing unit of the second image acquisition device 2 may, for example, binarize the image acquired by the visible light camera to obtain the silhouette of the subject H Alternatively, it is converted into an image consisting only of skin line information (outline) and transmitted to the console 3. Alternatively, the shadow of the side of the subject H obtained by irradiating the side of the subject H with light from the light source is captured by a visible light camera, and an image of the shadow of the side of the subject H is acquired and transmitted to the console 3 It is also good.
When the control unit 31 of the console 3 receives an image from the first image acquisition device 1 and the second image acquisition device 2 by the communication unit 35, the control unit 31 stores the frame image and the side image of the received dynamic image in the RAM.

  Next, the control unit 31 executes subcutaneous soft tissue removal processing B on each frame image of the acquired dynamic image using the acquired one side image, and the dynamic of which the influence of the subcutaneous soft tissue is removed An image is generated (step S13).

  FIG. 7 shows the flow of the subcutaneous soft tissue removing process B performed in step S13. The subcutaneous soft tissue removing process B is executed by the cooperation of the control unit 31 and the program stored in the storage unit 32. The subcutaneous soft tissue removing process B will be described below with reference to FIG.

First, the control unit 31 specifies the thickness of the subcutaneous soft tissue at each pixel position of each frame image of the dynamic image based on the side image (step S131).
The subcutaneous soft tissue in the chest is approximately the breast, with fat and mammary gland as the main components. By specifying the thickness of the subcutaneous soft tissue (breast) at each pixel of the frame image of the dynamic image, it is possible to specify the transmission distance of radiation at each pixel.

  In step S132, (a) a method of estimating from the movement of the lower breast line, (b) a method of estimating from the movement of bones such as ribs, as a method of specifying the thickness of subcutaneous soft tissue at each pixel of each frame image. (C) Any of the methods of estimating from lung field movement can be used. Each of these will be described below.

(A) Method of Estimating from Movement of Bottom Breast Line First, the bottom breast line as a feature point of the subcutaneous soft tissue is detected from the side image.
Next, edge detection is performed on the frame image of the dynamic image captured at the same timing as the side image, and an edge having the y coordinate at substantially the same position as the breast lower end line detected from the side image is detected as the breast lower end line. As for other frame images, the lower edge line of the breast is detected by separately detecting the vicinity of the lower edge line of the breast detected from the frame image captured at the same timing as the side surface image.
Then, the difference between the lower breast line of the frame image of the dynamic image taken at the same timing as that of the side image and the other frame image is the frame image of the dynamic image taken at the same timing as the lateral image and the other frame images Calculated as the movement amount of the lower breast line between
Next, for example, the distribution of the thickness of the subcutaneous soft tissue for each y coordinate is acquired from the side image. For example, the distance between the x-coordinate of the skin line at each y-coordinate and the x-coordinate of the skin line at the bottom of the breast lower end line is acquired as the thickness of the subcutaneous soft tissue at each y-coordinate. The position where the thickness is greater than 0 is the position of the subcutaneous soft tissue.
The relative position between the breast lower end line and the thickness distribution of the subcutaneous soft tissue is regarded as unchanged, and the thickness of the subcutaneous soft tissue in the side image according to the movement amount of the breast lower end line calculated for each frame image of the dynamic image. Is translated to identify the thickness of subcutaneous soft tissue at each pixel position of each frame image.

(B) Method of Estimating from Movements of Bones such as Ribs First, a bone portion (here, ribs) is detected for each frame image of a dynamic image. The method of detecting the rib contour is not particularly limited, and a known method can be applied as disclosed in, for example, JP-A-5-176919.
Next, the difference in the position of the y coordinate of the rib between the frame image of the dynamic image taken at the same timing as the side image and the frame image of the dynamic image taken at the same timing as the lateral image It is calculated as the movement amount of the rib between the frame image.
Next, for example, the distribution of the thickness of the subcutaneous soft tissue for each y coordinate is acquired from the side image. For example, the distance between the x-coordinate of the skin line at each y-coordinate and the x-coordinate of the skin line under the lower breast line is acquired as the thickness. The position where the thickness is greater than 0 is the position of the subcutaneous soft tissue.
The subcutaneous soft tissue such as the breast is considered to move up and down in the same direction and the same amount of movement according to the movement of the ribs, and the thickness of the subcutaneous soft tissue in the side image according to the movement of the ribs detected in each frame image of the dynamic image. Is translated to identify the thickness of subcutaneous soft tissue at each pixel position of each frame image.

(C) Method of Estimating from Movement of Lung Field As a premise of processing, a standard value of the relationship between the movement of the lung field and the movement of the breast accompanying it is calculated in advance by statistical processing and stored in the storage unit 32.
In step S131, lung field extraction is first performed for each frame image of the dynamic image. The lung field region may be extracted from each frame image using any known method. For example, a threshold value is obtained from the histogram of pixel values of each pixel of each frame image by discriminant analysis, and a region having a signal higher than the threshold value is primarily extracted as a lung field region candidate. Then, edge detection is performed near the boundary of the primary lung field region candidate extracted, and the boundary of the lung region can be extracted by extracting the point where the edge is maximum in the small region near the boundary along the boundary. it can.
Then, the difference of the y-coordinate position of the lung area between the frame image of the dynamic image taken at the same timing as the side image and the other frame image is the frame image of the dynamic image taken at the same timing as the side image It is calculated as the amount of movement of the lung region with respect to the other frame images. The position of the y-coordinate of the lung region may be, for example, an average value of the y-coordinates of the contour of the lower portion of the lung region.
Next, for example, the distribution of the thickness of the subcutaneous soft tissue for each y coordinate is acquired from the side image. For example, the distance between the x-coordinate of the skin line at each y-coordinate and the x-coordinate of the skin line under the lower breast line is acquired as the thickness.
Then, from the relationship between the movement of the lung field calculated for each frame image of the dynamic image and the movement of the lung field and the breast calculated in advance, the movement of the subcutaneous soft tissue including the breast was estimated and estimated. The thickness distribution of the subcutaneous soft tissue in the side image is moved in parallel according to the amount of movement, and the thickness of the subcutaneous soft tissue at each pixel position in the lung field region of each frame image is acquired.

  Next, the control unit 31 calculates the radiation attenuation amount (correction value) of each pixel of the frame image of the dynamic image based on the SID at the dynamic imaging, the mAs value, and the thickness of the subcutaneous soft tissue (step S132). Since the process of step S132 is the same as that described in step S32, the description will be used.

  Next, the control unit 31 corrects each pixel value of each frame image of the dynamic image using the calculated radiation attenuation amount (step S133), and proceeds to step S14 in FIG. Since the process of step S133 is the same as that described in step S33, the description will be used.

In step S14 of FIG. 6, the control unit 31 performs kinetic analysis using each frame image of the kinetic image from which the influence of the subcutaneous soft tissue has been removed (step S14).
Then, the result of the kinetic analysis is displayed on the display unit 34 (step S15), and the image acquisition process B is ended.

  As described above, the first and second embodiments of the present invention have been described, but the contents described in the above-described embodiments and modifications are preferred examples of the radiation imaging system according to the present invention, and Absent.

  For example, in the above embodiment, the second image acquisition device 2 acquires a side image of the subject H by various sensors, and the console 3 specifies the position and thickness of the subcutaneous soft tissue based on the side image. Although the embodiment of the present invention is not limited to this. For example, the second image acquisition device 2 performs radiation imaging of the subject H from a direction different from the radiation image of the first image acquisition device 1, and the acquired radiation image and the first image acquisition device 1 It is also possible to acquire a stereoscopic image capturing the subcutaneous soft tissue of the living body based on the radiographic image and to identify the position and thickness of the subcutaneous soft tissue based on the stereoscopic image. The function of generating a stereoscopic image from two radiation images may be provided in the second image acquisition device 2 or may be realized by the control unit 31 of the console 3. That is, the function as the second image acquisition unit may be realized by cooperation of the second image acquisition device 2 and the console 3.

  Further, in the above embodiment, the radiation attenuation amount is estimated by specifying the position and thickness of the subject H for the pixels of the entire area of each frame of the dynamic image. The radiation attenuation amount may be estimated by specifying the position and thickness.

  Moreover, in the said embodiment, although demonstrated as performing a kinetic analysis based on the dynamic image which removed the influence of a subcutaneous soft tissue, the display of the dynamic image which removed the influence of a subcutaneous soft tissue for a doctor's diagnosis It may be displayed on 34.

  In the above embodiment, the present invention is applied to the case of removing the influence of the subcutaneous soft tissue from the dynamic image of the chest. However, the present invention is not limited thereto, and a radiation image of another part ( The present invention is also applicable to the case of removing the influence of subcutaneous soft tissue from dynamic images, still images).

  In the above description, an example using a hard disk, a non-volatile memory of a semiconductor or the like as a computer readable medium of the program according to the present invention has been disclosed, but the present invention is not limited to this example. As another computer readable medium, a portable recording medium such as a CD-ROM can be applied. In addition, carrier wave (carrier wave) is also applied as a medium for providing data of the program according to the present invention through a communication line.

  In addition, the detailed configuration and the detailed operation of each device constituting the radiation imaging system can be appropriately modified without departing from the scope of the invention.

100 radiation imaging system 1 first image acquisition device 11 radiation source 12 imaging control unit 13 exposure switch 14 radiation detection unit 15 communication unit 2 second image acquisition device 3 console 31 control unit 32 storage unit 33 operation unit 34 display unit 35 Communication unit 36 Bus

Claims (9)

A first image acquisition unit configured to acquire a radiation image of the living body by irradiating the living body with radiation and capturing the radiation;
A second image acquisition unit that acquires an image obtained by capturing the subcutaneous soft tissue of the living body by imaging the living body from a direction different from that of the first image acquisition unit;
The position and thickness of the subcutaneous soft tissue of the living body included in the radiation image are specified based on the image acquired by the second image acquisition unit, and the position and thickness of the subcutaneous soft tissue of the living body specified are specified. Estimation means for estimating the radiation attenuation amount by the subcutaneous soft tissue at each pixel of the radiation image;
A correction unit configured to correct the radiation image based on the radiation attenuation amount estimated by the estimation unit;
Radiography system provided with   The second image acquisition unit according to claim 1, wherein the living body is imaged from a direction different from the first image acquisition unit by a visible light camera, an infrared sensor, a microwave sensor, an ultrasonic sensor, or a radar sensor. Radiography system. The first image acquisition means acquires a radiation image of the front of the living body,
The radiation imaging system according to claim 2, wherein the second image acquisition unit acquires an image of a side surface of the living body.   The second image acquisition means converts and acquires an image obtained by photographing the side of the living body with the visible light camera into an image showing only a silhouette or outline of the side of the living body. Radiographic system as described.   The second image acquisition unit captures, with the visible light camera, a shadow of the side surface of the living body obtained by irradiating light from the light source to the side surface of the living body, and acquires an image of the shadow of the side surface of the living body The radiation imaging system according to claim 3.   The second image acquisition means radiographs the living body from a direction different from that of the first image acquisition means, and the obtained radiation image and the radiation image obtained by the first image acquisition means The radiography system according to claim 1 which acquires a three-dimensional picture which caught subcutaneous soft tissue of said living body based on it. The first image acquisition unit acquires a plurality of frame images indicating the movement of the living body by dynamic imaging.
The second image acquisition unit captures a plurality of the images by capturing the living body at the same timing as each of the plurality of frame images captured by the first image acquisition unit.
The estimation unit is a position of subcutaneous soft tissue of the living body included in each frame image acquired by the first image acquisition unit based on the images acquired at the same timing by the second image acquisition unit. The radiographic imaging system as described in any one of Claims 1-6 which specifies thickness. The first image acquisition unit acquires a plurality of frame images indicating the movement of the living body by dynamic imaging.
The second image acquisition unit captures the image of the living body at the same timing as any one of the plurality of frame images by the first image acquisition unit, and acquires the image.
The estimation means detects the position of the feature point of the subcutaneous soft tissue of the living body from each of the plurality of frame images, and the position of the feature point detected in each of the frame images and the second image acquisition means The difference between the timing at which the image is acquired and the position of the feature point detected in the frame image acquired at the same timing as the timing at which each frame image is acquired and the image acquisition by the second image acquisition means Position and thickness of the subcutaneous soft tissue of the living body which is calculated based on the image acquired by the second image acquiring means, calculated as the movement amount of the feature point between The position and thickness of the subcutaneous soft tissue of the living body included in each of the frame images are specified based on the movement amount calculated for Radiation imaging system according to any one of. The first image acquisition unit acquires a plurality of frame images indicating the movement of the living body by dynamic imaging.
The second image acquisition unit captures the image of the living body at the same timing as any one of the plurality of frame images by the first image acquisition unit, and acquires the image.
The estimation unit detects a predetermined structure from each of the plurality of frame images, and the image is acquired by the position of the predetermined structure detected in each of the frame images and the second image acquisition unit. The timing at which each frame image is acquired and the timing at which the image is acquired by the second image acquisition means are the difference from the position of the predetermined structure detected in the frame image acquired at the same timing as the timing Of the position and thickness of the subcutaneous soft tissue of the living body which is calculated based on the image acquired by the second image acquiring means and calculated as the amount of movement of the predetermined structure between The position and thickness of the subcutaneous soft tissue of the living body included in each of the frame images are specified based on the calculated amount of movement. Radiation imaging system according to an item or Re.