JP2019005417A - Dynamic image processing device and dynamic image processing system - Google Patents

Abstract

To suppress a flicker noise due to a signal estimation error of a structure in a dynamic chest image in which the structure is attenuated.SOLUTION: A control part 31 of a diagnosis console 3 determines a frame image used for correction of a signal value caused by a prescribed structure which is estimated for each of plural frame images acquired by dynamic imaging of a chest part from other frame images which are different from the correction object frame image, then performs identification of a shape of an area of the prescribed structure in the determined frame image to a shape of an area of the prescribed structure in the correction object frame image, then corrects an estimated signal value in the correction object frame image by using the estimated signal value in the frame image whose shape is subjected to identification. Then, based on the corrected estimated signal value, a signal component due to the prescribed structure in each of plural frame images is attenuated.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a dynamic image processing apparatus and a dynamic image processing system.

  In the X-ray image of the chest, not only the lung field to be diagnosed, but also structures such as ribs, clavicles and blood vessels that cover it are reflected at the same time. These hinder the diagnosis of the lung field.

  Therefore, for example, in Patent Document 1, a region of a structure such as a rib or a clavicle is extracted from each of a plurality of frame images of a chest dynamic image, and a signal component due to the structure of the extracted region is estimated. The subtraction is described from the frame image. Further, it is described that an error in estimating a signal component due to a structure between frame images is corrected using a plurality of frame images.

Japanese Patent Laid-Open No. 2006-73466

  Since hard structures (skeletons such as ribs and clavicles) hardly change in shape between adjacent frame images, suppression of signal estimation errors by the method described in Patent Document 1 can obtain a desired result. is expected. However, the shape of soft tissue such as blood vessels and the heart changes between adjacent frame images, and it is not possible to estimate the correct signal value simply by correcting using the representative value of the estimated signal value between the frame images. It can't be done and looks like an artifact. Even if it is a hard structure, when trying to increase the accuracy of signal estimation using non-adjacent frame images, the structure moves with breathing and the positional relationship with the X-ray source changes. Thus, since the shape is deformed on the image, it is difficult to correctly estimate the signal as in the case of the blood vessels and the heart. If there is a frame image that causes an error in signal estimation of the structure, there is a problem that flickering occurs when the attenuated dynamic image is reproduced, and it is difficult to observe the diagnosis target.

  An object of the present invention is to suppress flicker noise due to a signal estimation error of a structure in a chest dynamic image in which the structure is attenuated.

In order to solve the above-described problem, a dynamic image processing apparatus according to claim 1 is provided.
Extraction means for extracting a region of a predetermined structure from each of a plurality of frame images acquired by dynamic imaging of the chest of the subject;
Estimating means for estimating a signal value caused by the predetermined structure in the region of the predetermined structure extracted by the extracting means;
Determining means for determining a frame image to be used for correcting the estimation result by the estimating means in each of the plurality of frame images from a frame image different from the frame image to be corrected in the plurality of frame images;
The shape of the region of the predetermined structure in the frame image used for the correction determined by the determination unit is made the same as the shape of the region of the predetermined structure in the frame image to be corrected, and the shape is made the same Correction means for correcting the estimation result in the frame image to be corrected using the estimation result in a frame image;
Attenuating means for attenuating a signal component caused by the predetermined structure in each of the plurality of frame images based on the estimation result corrected by the correcting means;
Is provided.

The invention according to claim 2 is the invention according to claim 1,
The determination means includes a speed, period or frequency of movement of the diaphragm in the plurality of frame images, a speed, period or frequency of concentration change in the lung field in the plurality of frame images, a respiratory state during dynamic imaging of the subject, or Based on the disease of the subject, the number of frame images used for the correction is determined, and the determined number of frame images before and after the correction target frame image are determined as the frame images used for the correction.

The invention according to claim 3 is the invention according to claim 1 or 2,
The correction unit replaces the estimation result in the correction target frame image with a representative value of the estimation result at a position corresponding to the estimation result and the frame image used for the correction.

The invention according to claim 4 is the invention according to any one of claims 1 to 3,
The correction means determines whether or not an outlier is included in the estimation result in the frame image to be corrected based on the estimation result in the frame image used for the correction, and when the outlier is included The correction is performed for the outlier.

The dynamic image processing system of the invention according to claim 5 is:
Photographing means for performing dynamic photographing on the chest of the subject;
Extracting means for extracting a region of a predetermined structure from each of a plurality of frame images acquired by the photographing means;
Estimating means for estimating a signal value caused by the predetermined structure in the region of the predetermined structure extracted by the extracting means;
Determining means for determining a frame image to be used for correcting the estimation result by the estimating means in each of the plurality of frame images from a frame image different from the frame image to be corrected in the plurality of frame images;
The shape of the region of the predetermined structure in the frame image used for the correction determined by the determination unit is made the same as the shape of the region of the predetermined structure in the frame image to be corrected, and the shape is made the same Correction means for correcting the estimation result in the frame image to be corrected using the estimation result in a frame image;
Attenuating means for attenuating a signal component caused by the predetermined structure in each of the plurality of frame images based on the estimation result corrected by the correcting means;
Is provided.

  According to the present invention, it is possible to suppress flicker noise due to a signal estimation error of a structure in a chest dynamic image in which the structure is attenuated.

1 is a diagram illustrating an overall configuration of a dynamic image processing system in an embodiment of the present invention. 3 is a flowchart illustrating a shooting control process executed by a control unit of the shooting console of FIG. 1. It is a flowchart which shows the structure attenuation process performed by the control part of the diagnostic console of FIG. It is a figure which shows typically the processing content of the structure attenuation | damping process of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

[Configuration of Dynamic Image Processing System 100]
First, the configuration of the present embodiment will be described.
FIG. 1 shows the overall configuration of a dynamic image processing system 100 in the present embodiment.
As shown in FIG. 1, in the dynamic image processing system 100, an imaging device 1 and an imaging console 2 are connected by a communication cable or the like, and the imaging console 2 and the diagnostic console 3 are connected to a LAN (Local Area Network). Etc., and connected via a communication network NT. Each device constituting the dynamic image processing system 100 conforms to the DICOM (Digital Image and Communications in Medicine) standard, and communication between the devices is performed according to DICOM.

[Configuration of the photographing apparatus 1]
The imaging device 1 is an imaging unit that images dynamics of a living body, such as changes in the shape of lung expansion and contraction associated with respiratory motion, heart pulsation, and the like. Dynamic imaging is to irradiate a subject repeatedly with a pulse of X-ray radiation (pulse irradiation) or continuously with a low dose rate without interruption (continuous irradiation). In other words, obtaining a plurality of images showing the dynamics of the subject. A series of images obtained by dynamic imaging is called a dynamic image. Each of the plurality of images constituting the dynamic image is called a frame image. In the following embodiment, a case where dynamic imaging of the chest is performed by pulse irradiation will be described as an example.

The radiation source 11 is disposed at a position facing the radiation detection unit 13 across the subject M, and irradiates the subject M with radiation (X-rays) according to the control of the radiation irradiation control device 12.
The radiation irradiation control device 12 is connected to the imaging console 2 and controls the radiation source 11 based on the radiation irradiation conditions input from the imaging console 2 to perform radiation imaging. The radiation irradiation conditions input from the imaging console 2 are, for example, pulse rate, pulse width, pulse interval, number of imaging frames per imaging, X-ray tube current value, X-ray tube voltage value, additional filter type, etc. It is. The pulse rate is the number of times of radiation irradiation per second, and matches the frame rate described later. The pulse width is a radiation irradiation time per one irradiation. The pulse interval is a time from the start of one radiation irradiation to the start of the next radiation irradiation, and coincides with a frame interval described later.

The radiation detection unit 13 includes a semiconductor image sensor such as an FPD (Flat Panel Detector). The FPD has, for example, a glass substrate or the like, detects radiation that has been irradiated from the radiation source 11 and transmitted through at least the subject M at a predetermined position on the substrate according to its intensity, and detects the detected radiation as an electrical signal. A plurality of detection elements (pixels) converted and stored in a matrix are arranged in a matrix. Each pixel includes a switching unit such as a TFT (Thin Film Transistor). The FPD includes an indirect conversion type in which X-rays are converted into electric signals by a photoelectric conversion element via a scintillator, and a direct conversion type in which X-rays are directly converted into electric signals, either of which may be used.
The radiation detection unit 13 is provided to face the radiation source 11 with the subject M interposed therebetween.

  The reading control device 14 is connected to the imaging console 2. The reading control device 14 controls the switching unit of each pixel of the radiation detection unit 13 based on the image reading condition input from the imaging console 2 to switch the reading of the electrical signal accumulated in each pixel. Then, the image data is acquired by reading the electrical signal accumulated in the radiation detection unit 13. This image data is a frame image. The pixel signal value of the frame image represents a density value. Then, the reading control device 14 outputs the acquired frame image to the photographing console 2. The image reading conditions are, for example, a frame rate, a frame interval, a pixel size, an image size (matrix size), and the like. The frame rate is the number of frame images acquired per second and matches the pulse rate. The frame interval is the time from the start of one frame image acquisition operation to the start of the next frame image acquisition operation, and coincides with the pulse interval.

  Here, the radiation irradiation control device 12 and the reading control device 14 are connected to each other, and exchange synchronization signals to synchronize the radiation irradiation operation and the image reading operation.

[Configuration of the shooting console 2]
The imaging console 2 outputs radiation irradiation conditions and image reading conditions to the imaging apparatus 1 to control radiation imaging and radiographic image reading operations by the imaging apparatus 1, and also captures dynamic images acquired by the imaging apparatus 1. The image is displayed for confirming whether the image is suitable for confirmation of positioning or diagnosis by a photographer.
As shown in FIG. 1, the imaging console 2 includes a control unit 21, a storage unit 22, an operation unit 23, a display unit 24, and a communication unit 25, and each unit is connected by a bus 26.

The control unit 21 includes a CPU (Central Processing Unit) and a RAM (Random Access Memory).
) Etc. The CPU of the control unit 21 reads the system program and various processing programs stored in the storage unit 22 in accordance with the operation of the operation unit 23, expands them in the RAM, and performs shooting control processing described later according to the expanded programs. Various processes including the beginning are executed to centrally control the operation of each part of the imaging console 2 and the radiation irradiation operation and the reading operation of the imaging apparatus 1.

  The storage unit 22 is configured by a nonvolatile semiconductor memory, a hard disk, or the like. The storage unit 22 stores various programs executed by the control unit 21 and data such as parameters necessary for execution of processing by the programs or processing results. For example, the storage unit 22 stores a program for executing the shooting control process shown in FIG. The storage unit 22 stores the radiation irradiation condition and the image reading condition in association with the examination target part (here, the chest). Various programs are stored in the form of readable program code, and the control unit 21 sequentially executes operations according to the program code.

  The operation unit 23 includes a keyboard having a cursor key, numeric input keys, various function keys, and the like, and a pointing device such as a mouse. The control unit 23 controls an instruction signal input by key operation or mouse operation on the keyboard. To 21. In addition, the operation unit 23 may include a touch panel on the display screen of the display unit 24. In this case, the operation unit 23 outputs an instruction signal input via the touch panel to the control unit 21.

  The display unit 24 is configured by a monitor such as an LCD (Liquid Crystal Display) or a CRT (Cathode Ray Tube), and displays an input instruction, data, or the like from the operation unit 23 in accordance with an instruction of a display signal input from the control unit 21. To do.

  The communication unit 25 includes a LAN adapter, a modem, a TA (Terminal Adapter), and the like, and controls data transmission / reception with each device connected to the communication network NT.

[Configuration of diagnostic console 3]
The diagnostic console 3 is a dynamic image processing device that acquires a dynamic image from the imaging console 2 and displays the acquired dynamic image by performing image processing.
As shown in FIG. 1, the diagnostic console 3 includes a control unit 31, a storage unit 32, an operation unit 33, a display unit 34, and a communication unit 35, and each unit is connected by a bus 36.

  The control unit 31 includes a CPU, a RAM, and the like. The CPU of the control unit 31 reads the system program and various processing programs stored in the storage unit 32 in accordance with the operation of the operation unit 33 and develops them in the RAM, and the structure attenuation process according to the developed programs. Various processes including the above are executed, and the operation of each part of the diagnostic console 3 is centrally controlled. The control unit 31 functions as an extraction unit, an estimation unit, a determination unit, a correction unit, and an attenuation unit.

  The storage unit 32 is configured by a nonvolatile semiconductor memory, a hard disk, or the like. The storage unit 32 stores various programs including a program for executing an analysis process in the control unit 31, parameters necessary for executing the process by the program, or data such as a process result. These various programs are stored in the form of readable program codes, and the control unit 31 sequentially executes operations according to the program codes.

  Further, in the storage unit 32, a dynamic image taken in the past includes an identification ID, patient information (eg, patient ID, patient (subject) name, height, weight, age, sex, disease, etc.), examination information. (For example, examination ID, examination date, examination target part (here, chest), respiratory state to be photographed, etc.) are stored in association with each other.

  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. The operation unit 33 receives an instruction signal input by a key operation or a mouse operation on the keyboard by the user. Output to the control unit 31. The operation unit 33 may include a touch panel on the display screen of the display unit 34, and in this case, an instruction signal input via the touch panel is output to the control unit 31.

  The display unit 34 is configured by a monitor such as an LCD or a CRT, and performs various displays according to instructions of a display signal input from the control unit 31.

  The communication unit 35 includes a LAN adapter, a modem, a TA, and the like, and controls data transmission / reception with each device connected to the communication network NT.

[Operation of Dynamic Image Processing System 100]
Next, the operation of the dynamic image processing system 100 in the present embodiment will be described.

(Operation of the photographing apparatus 1 and the photographing console 2)
First, the photographing operation by the photographing apparatus 1 and the photographing console 2 will be described.
FIG. 2 shows photographing control processing executed in the control unit 21 of the photographing console 2. The photographing control process is executed in cooperation with the control unit 21 and a program stored in the storage unit 22.

  First, the operation part 23 of the imaging console 2 is operated by the imaging operator, and patient information and examination information are input (step S1).

  Next, the radiation irradiation conditions are read from the storage unit 22 and set in the radiation irradiation control device 12, and the image reading conditions are read from the storage unit 22 and set in the reading control device 14 (step S2).

  Next, a radiation irradiation instruction by the operation of the operation unit 23 is waited (step S3). Here, the imaging operator places the subject M between the radiation source 11 and the radiation detection unit 13 to perform positioning. Further, the subject (subject M) is instructed to breathe (deep breathing, rest breathing, breath holding, etc.). When preparation for imaging is completed, the operation unit 23 is operated to input a radiation irradiation instruction.

  When a radiation irradiation instruction is input by the operation unit 23 (step S3; YES), a photographing start instruction is output to the radiation irradiation control device 12 and the reading control device 14, and dynamic photographing is started (step S4). That is, radiation is emitted from the radiation source 11 at a pulse interval set in the radiation irradiation control device 12, and a frame image is acquired by the radiation detection unit 13.

  When photographing of a predetermined number of frames is completed, the control unit 21 outputs a photographing end instruction to the radiation irradiation control device 12 and the reading control device 14, and the photographing operation is stopped. The number of frames to be captured is the number of frames that can be captured for at least one respiratory cycle.

  The frame images acquired by shooting are sequentially input to the shooting console 2, stored in the storage unit 22 in association with a number (frame number) indicating the shooting order (step S5), and displayed on the display unit 24. (Step S6). The imaging operator confirms the positioning and the like from the displayed dynamic image, and determines whether an image suitable for diagnosis is acquired by imaging (imaging OK) or re-imaging is necessary (imaging NG). Then, the operation unit 23 is operated to input a determination result.

  When a determination result indicating photographing OK is input by a predetermined operation of the operation unit 23 (step S7; YES), an identification ID for identifying a dynamic image or each of a series of frame images acquired by dynamic photographing is displayed. Information such as patient information, examination information, radiation irradiation conditions, image reading conditions, imaging order number (frame number) is attached (for example, written in the header area of the image data in DICOM format), and the communication unit 25 is To the diagnostic console 3 (step S8). Then, this process ends. On the other hand, when a determination result indicating photographing NG is input by a predetermined operation of the operation unit 23 (step S7; NO), a series of frame images stored in the storage unit 22 is deleted (step S9), and this processing is performed. finish. In this case, re-shooting is necessary.

(Operation of diagnostic console 3)
Next, the operation in the diagnostic console 3 will be described.
When the diagnostic console 3 receives a series of frame images of the dynamic image from the imaging console 2 via the communication unit 35, the structure attenuation process is executed.
FIG. 3 shows a flowchart of the structure attenuation process. The structure attenuation process is executed in cooperation with the control unit 31 and the program stored in the storage unit 32.

  In the structure attenuation process, first, a lung field region is extracted for each frame image of the dynamic image (step S21).

  Any method may be used as the lung field extraction method in step S21. For example, as disclosed in Japanese Patent No. 2998733, in the X-ray image, in the lung field region, the image density of the left and right lung portions is higher than the surrounding density. Therefore, a density histogram of an arbitrary frame image is created, an image portion of a high density region corresponding to the lung field region is determined from the shape and area of the density histogram, and the contour of the image portion is extracted as the lung field contour. That's fine. Alternatively, as disclosed in Japanese Patent Application Laid-Open No. 2003-6661, the outline of a lung field region is extracted by performing template matching on an arbitrary frame image using a template that defines the outline of a standard lung field region. You can also

  Next, the region of the structure to be attenuated is extracted from the extracted lung field region (step S22). Examples of the structure to be attenuated include a bone part, a heart, and a blood vessel.

  The extraction method of the bone part is not particularly limited, and a known method can be applied. For example, as described in US Patent Application Publication No. 2014/0079309, it can be performed by a technique such as template matching with a rib template or clavicle template prepared in advance, or applying a curve fitting function after edge detection. Also, based on prior knowledge of bone structures such as ribs and clavicles, based on features such as position, shape, size, concentration gradient, direction, etc., we will investigate whether there is an error in the recognized bone region, The extracted part may be identified and removed from the bone region.

  The heart region extraction method is not particularly limited, and a known method can be applied. For example, as described in Japanese Patent No. 2796381, a boundary point on both the left and right sides of the contour of the heart is detected from the frame image, and a model function such as a moving dispersion trigonometric function is fitted to the detected boundary point, and the fitted model A method of determining the outline of the heart based on the function can be used.

  Moreover, the extraction method of the blood vessel region is not particularly limited, and a known method can be applied. For example, a blood vessel region can be extracted by extracting a line structure from a frame image using a Kasvand filter or Hessian matrix described in Japanese Patent Application Laid-Open No. 2017-18339.

  Next, in the structure region extracted from each frame image, a signal component (signal value) due to the structure is estimated (step S23).

  For example, the bone signal value is, for example, as described in WO 2015157067 A1, in an image in which a background trend (smooth signal change from the center of the lung field to the thorax) is removed by applying a low-pass filter to the lung field region, etc. It can be estimated by applying a smoothing filter along the extracted bone region. Or as described in Reference 1 (Seitaro Oda et al., Performance of Radiologists in Detection of Small Pulmonary Nodules on Chest Radiographs: Effect of Rib Suppression With a Massive-Training Artificial Neural Network, AJR193, Number5, November 2009) The bone signal may be estimated by a discriminator such as CNN or D-NN previously learned from correct answer data (Dual Energy Subtraction image or the like).

  Similarly, the signal value of the blood vessel can be estimated by applying a smoothing filter along the extracted blood vessel region in the image from which the background trend is removed, for example. The signal value of the heart can be estimated, for example, by applying a smoothing filter radially from the center of the extracted heart region in the image from which the background trend is removed. Further, the signal value may be estimated by a discriminator learned from correct answer data (Dual Energy Subtraction image or image attenuated by the above-described method) as in the case of bone.

  Next, for each frame image, another frame image used for correcting the estimated signal value is determined (step S24).

  In step S24, for example, the moving period (frequency) of the diaphragm is calculated from the dynamic image, and the number of frame images used for correcting the estimated signal value is determined based on the calculated moving period (frequency) of the diaphragm. For example, a table in which the moving period (frequency) of the diaphragm and the number of frame images used for correction are associated in advance is stored in the storage unit 32, and the calculated moving period (frequency) and the table stored in the storage unit 32 are stored. Based on this, the number of frame images used for correction is determined. For example, when the calculated moving period (frequency) of the diaphragm is a moving period of the diaphragm (about 3.3 to 5 seconds (0.2 Hz to 0.3 Hz)) in a normal healthy person, the frame image to be corrected Two frame images before and after are determined as frame images used for correction. When the calculated frequency is shorter than the moving period of the diaphragm in a normal healthy person (frequency is high), one frame image before and after the frame image to be corrected is determined as a frame image used for correction.

  Here, in the X-ray image obtained by photographing the front of the chest, the contour of the lower lung field becomes the boundary with the diaphragm, and therefore the diaphragm region in each frame image can be extracted by extracting the lower contour of the lung field region. it can. In addition, the moving period of the diaphragm is, for example, moved from the lowest coordinate position to the highest position in the horizontal direction of either one of the extracted left and right diaphragms and then returned to the original position. The time until return can be calculated as the movement period of the diaphragm. The frequency of diaphragm movement can be obtained by calculating the reciprocal of the movement period.

  Alternatively, for each frame image, the moving speed (movement amount) of the diaphragm with the adjacent frame image is calculated, and the number of frame images used for correcting the estimated signal value of each frame image based on the calculated moving speed May be determined. For example, a table in which the moving speed of the diaphragm and the number of frame images used for correction are associated in advance is stored in the storage unit 32 and used for correction based on the calculated moving speed and the table stored in the storage unit 32. Determine the number of frame images. For example, the number of frame images used for correction is reduced for frame images with a fast diaphragm moving speed, and the number of frame images used for correction is increased for frame images with a slow diaphragm moving speed. Based on the determined number of frame images, the determined number of frame images before and after the frame image to be corrected are determined as frame images to be used for correction.

  In this way, when the moving speed of the diaphragm is slow, the number of frame images is determined so that more frame images before and after the influence, and conversely, when the moving speed of the diaphragm is fast, the frames before and after that are close in time By only affecting the image, it is possible to prevent the correction by the previous and next frame images from adversely affecting the signal value and to improve the correction accuracy of the signal value.

  In the above description, the number of frame images used for correcting the estimated signal value is determined based on the moving period (frequency) and moving speed of the diaphragm, but instead of these, the density of the lung field region is determined. The period (frequency) of change (time change of density value) and the speed of density change may be used. For example, since the diaphragm does not move much for a patient with a disease, it is preferable to determine the number of frame images used for correcting the signal value estimated using the density change.

  Further, for example, a table in which a respiratory state (rest breathing, deep breathing, breath holding) or a disease is associated with the number of frame images used for correcting the estimated signal value in advance is stored in the storage unit 32, and the storage unit The number of frame images used for correcting the estimated signal value may be determined based on the table stored in 32.

  Next, the shape of the structure area of the frame image to be corrected and the other frame image used for correction are made identical (step S25).

  In step S25, for example, the structure area extracted from the correction target frame image is divided into small areas, and the position of each of the other frame images corresponding to each small area is obtained by pattern matching (local matching). By calculating the movement amount and movement direction of the feature points of each small area and performing warping processing based on the obtained movement amount and movement direction, the shape of the structure area in the other frame image is the frame image in the correction target. Align (align) with the shape of the structure area at.

  In addition, when the structure to be attenuated is a bone part, the movement amount of the bone part according to the age, sex, disease, and respiratory state (rest breathing, deep breathing, breath holding, etc.) from previously acquired dynamic images Information (parallel movement amount per frame, rotational movement amount, etc.) is created and stored in the storage unit 32, and the movement amount information stored in the storage unit 32 and the age and sex of the dynamic image to be corrected Based on the disease and respiratory state, the shape of each bone region of another frame image used for correction may be translated and / or rotated to match the shape of the bone region of the correction target frame image. .

  Next, the estimated signal value of each frame image is corrected based on the estimated signal value in the frame image used for correction (each frame image whose shape is identical in step S25) (step S26).

In step S26, for example, for each pixel in the structure region extracted from the frame image to be corrected, the pixel and the pixel at the same coordinate in the other frame image used for correction (the pixel at the corresponding position) are estimated. A representative value of the signal value (for example, an average value, a median value, or a weighted average value obtained by weighting a frame image used for correction) is calculated, and an estimated signal in the structure area of the frame image to be corrected The value is replaced with the calculated representative value.
Alternatively, for each pixel in the structure area extracted from the frame image to be corrected, the estimated signal value of the pixel is significantly different from the estimated signal value of the pixel at the same coordinate in another frame image used for correction. If it is an outlier, the estimated signal value of the pixel is used as a representative of the estimated signal value of the pixel at the same coordinate in another frame image used for correction. It may be replaced with a value. Whether the value is an outlier or not is determined based on, for example, an estimated signal value of a pixel to be corrected based on an upper limit value or a lower limit value of an estimated signal value of a pixel having the same coordinate in another frame image used for correction. When the value is more than the value, it can be determined that the value is an outlier.

  Then, by subtracting the corrected estimated signal value from each frame image, the signal component due to the structure is attenuated (step S27), and the structure attenuation process ends. Specifically, the corrected signal value is subtracted from the signal value of each pixel of the structure region extracted from each frame image, and the signal component due to the structure is attenuated from each frame image.

  The chest dynamic image in which the structure is attenuated by the structure attenuation process is displayed as a moving image on the display unit 34 by the control unit 31. Alternatively, an analysis process such as performing an inter-frame difference between adjacent frame images may be performed, and the analysis result may be displayed on the display unit 34.

  FIG. 4 is a diagram schematically showing the processing contents of the structure attenuation processing. As shown in FIG. 4, in the structure attenuation process, the shape of the structure area in the frame image used for correction is matched with the shape of the structure area in the frame image to be corrected, and then the frame image to be corrected is estimated. The signal value is corrected based on the estimated signal value in the frame image used for correction. Therefore, the estimation error of the signal component caused by the structure between the frame images can be suppressed with high accuracy, and the flicker noise due to the signal estimation error of the structure in the chest dynamic image with the structure attenuated can be suppressed. .

As described above, according to the control unit 31 of the diagnostic console 3, a region of a predetermined structure is extracted from each of a plurality of frame images obtained by dynamic imaging of the chest, and in the extracted region A signal value caused by a predetermined structure is estimated. Next, a frame image used for correcting the estimated signal value in each of the plurality of frame images is determined from frame images different from the frame image to be corrected, and a predetermined structure in the frame image used for the determined correction The shape of the region of the object is made the same as the shape of the region of the predetermined structure in the frame image to be corrected, and the estimated signal value in the frame image to be corrected using the estimated signal value in the frame image having the same shape Correct the value. Then, based on the corrected estimated signal value, a signal component caused by a predetermined structure in each of the plurality of frame images is attenuated.
Therefore, the estimation error of the signal component caused by the structure between the frame images can be suppressed with high accuracy, and the flicker noise due to the signal estimation error of the structure in the chest dynamic image with the structure attenuated can be suppressed. .

  For example, the control unit 31 may control the speed, period or frequency of the movement of the diaphragm in the plurality of frame images, the speed, period or frequency of the concentration change in the lung field in the plurality of frame images, the breathing state during dynamic imaging of the subject, or the subject. The number of frame images used for correction is determined based on the disease, and the frame image used for correction is determined based on the determined number of frame images. Therefore, an optimal number of frame images can be used for correction based on the speed of breathing, the breathing state, and the disease at the time of photographing.

  The control unit 31 corrects the estimation result in the correction target frame image by replacing the estimation result in the correction target frame image with a representative value of the estimation result and the estimation result at the corresponding position of the frame image used for correction. . Therefore, it is possible to easily correct the estimation result in the correction target frame image using the estimation result of the frame image used for correction.

  Further, the control unit 31 determines whether or not an outlier is included in the estimation result in the correction target frame image based on the estimation result in the frame image used for correction, and when the outlier is included. By correcting the outlier, the processing time can be shortened.

  In addition, the description content in the said embodiment is a suitable example of this invention, and is not limited to this.

  For example, in the above embodiment, after estimating a signal value due to a structure in a region of a predetermined structure of each frame image of the chest dynamic image, the shape of the region of the predetermined structure in the frame image used for correction In the above description, the shape of the region of the predetermined structure in the correction target frame image is made identical to the correction target frame image. However, after the shape is made identical, the signal value caused by the structure is estimated from each frame image. It is good also as performing.

  For example, in the above description, an example in which a hard disk, a semiconductor nonvolatile memory, or the like is used as a computer-readable medium of the program according to the present invention is 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. A carrier wave is also applied as a medium for providing program data according to the present invention via a communication line.

  In addition, the detailed configuration and detailed operation of each device constituting the dynamic image processing system can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 Dynamic image processing system 1 Imaging device 11 Radiation source 12 Radiation irradiation control device 13 Radiation detection part 14 Reading control device 2 Imaging console 21 Control part 22 Storage part 23 Operation part 24 Display part 25 Communication part 26 Bus 3 Diagnosis console 31 Control unit 32 Storage unit 33 Operation unit 34 Display unit 35 Communication unit 36 Bus

Claims (5)

Extraction means for extracting a region of a predetermined structure from each of a plurality of frame images acquired by dynamic imaging of the chest of the subject;
Estimating means for estimating a signal value caused by the predetermined structure in the region of the predetermined structure extracted by the extracting means;
Determining means for determining a frame image to be used for correcting the estimation result by the estimating means in each of the plurality of frame images from a frame image different from the frame image to be corrected in the plurality of frame images;
The shape of the region of the predetermined structure in the frame image used for the correction determined by the determination unit is made the same as the shape of the region of the predetermined structure in the frame image to be corrected, and the shape is made the same Correction means for correcting the estimation result in the frame image to be corrected using the estimation result in a frame image;
Attenuating means for attenuating a signal component caused by the predetermined structure in each of the plurality of frame images based on the estimation result corrected by the correcting means;
A dynamic image processing apparatus comprising:   The determination means includes a speed, period or frequency of movement of the diaphragm in the plurality of frame images, a speed, period or frequency of concentration change in the lung field in the plurality of frame images, a respiratory state during dynamic imaging of the subject, or The number of frame images used for the correction is determined based on the disease of the subject, and the determined number of frame images before and after the frame image to be corrected are determined as frame images used for the correction. Dynamic image processing device.   The dynamic image according to claim 1, wherein the correction unit replaces the estimation result in the correction target frame image with a representative value of the estimation result at a position corresponding to the estimation result and the frame image used for the correction. Processing equipment.   The correction means determines whether or not an outlier is included in the estimation result in the frame image to be corrected based on the estimation result in the frame image used for the correction, and when the outlier is included The dynamic image processing apparatus according to claim 1, wherein the correction is performed for the outlier. Photographing means for performing dynamic photographing on the chest of the subject;
Extracting means for extracting a region of a predetermined structure from each of a plurality of frame images acquired by the photographing means;
Estimating means for estimating a signal value caused by the predetermined structure in the region of the predetermined structure extracted by the extracting means;
Determining means for determining a frame image to be used for correcting the estimation result by the estimating means in each of the plurality of frame images from a frame image different from the frame image to be corrected in the plurality of frame images;
The shape of the region of the predetermined structure in the frame image used for the correction determined by the determination unit is made the same as the shape of the region of the predetermined structure in the frame image to be corrected, and the shape is made the same Correction means for correcting the estimation result in the frame image to be corrected using the estimation result in a frame image;
Attenuating means for attenuating a signal component caused by the predetermined structure in each of the plurality of frame images based on the estimation result corrected by the correcting means;
A dynamic image processing system comprising: