JP2010268979A - Moving image processor and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make medical physicians easily identify the sites with the ventilation function and the function of the pulmonary blood stream degraded in a lung from a dynamic image of a chest part. <P>SOLUTION: In a console 3 for diagnosis, a control part 31 acquires upper and lower positions of a diaphragm from each frame image of the dynamic image of the chest part transmitted from a photographing console 2 to calculate hourly changes in the upper and lower positions of the diaphragm while the area of the lung field of each frame image in the dynamic image is divided into a plurality of smaller blocks A1 to calculate hourly changes in pixel signal values within each smaller block A1 thus divided. Then, as to each of the smaller blocks A1, a phase-delay time is calculated between the hourly changes in the pixel signal values within the smaller block relative and the hourly changes in the upper and lower positions of the diaphragm and each smaller block A1 is shown on a display part 34 according to a brightness value to match the phase-delay time. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a moving image processing apparatus and a program.

  In contrast to the conventional still image and diagnosis of radiation using a film / screen or photostimulable phosphor plate, a dynamic image of the region to be examined is taken using a semiconductor image sensor such as an FPD (flat panel detector), Attempts have been made to apply it to diagnosis. Specifically, by utilizing the responsiveness of reading / erasing of image data of the semiconductor image sensor, pulsed radiation is continuously irradiated from the radiation source in accordance with the reading / erasing timing of the semiconductor image sensor. Take multiple shots per second to capture the dynamics of the area to be examined. By sequentially displaying a series of a plurality of images acquired by imaging, a doctor can recognize a series of movements of a region to be examined.

  Various techniques for displaying dynamic images in an easy-to-view manner have also been proposed. For example, in Patent Document 1, a dynamic image acquired continuously in time series is treated as a “spatio-temporal three-dimensional image” with a time direction as a depth, and a transverse image and sagittal image are created. A technique for displaying in an observable manner is described.

JP 2004-305487 A

  By the way, in pulmonary diagnosis, it is important to observe whether there is a place where the lung function (ventilation function or pulmonary blood flow function) is reduced. However, it is difficult for a doctor to observe a dynamic image and visually recognize an abnormal part of the function. In particular, there are individual differences in lung respiratory motion and heart pulsation, and it is difficult to visually recognize abnormalities in the ventilation function and pulmonary blood flow function in consideration of individual differences.

  An object of the present invention is to make it possible for a doctor to easily identify a portion where a lung ventilation function or a pulmonary blood flow function is lowered from a chest dynamic image.

In order to solve the above-described problem, a dynamic image processing apparatus according to claim 1 is provided.
Obtaining an index value indicating a periodic movement of a predetermined part from a chest dynamic image, calculating a time change of the index value, dividing a lung field region included in the chest dynamic image into a plurality of regions, Image analysis means for calculating a temporal change of a pixel signal value in each divided area and calculating a phase delay time of a temporal change in the pixel signal value in the area with respect to a temporal change in the index value for each area;
Display means for displaying the phase delay time calculated for each region;
Is provided.

The invention according to claim 2 is the invention according to claim 1,
The image analysis means determines whether or not the function of each region is abnormal based on whether or not the phase delay time calculated for each region exceeds a predetermined threshold,
The display means displays a determination result for each area.

The invention according to claim 3 is the invention according to claim 1 or 2,
The image analysis means calculates the phase delay time by extracting a pixel signal component having substantially the same frequency as the time change of the index value indicating the predetermined periodical motion of the predetermined region for each region.

The invention according to claim 4 is the invention according to any one of claims 1 to 3,
The periodic motion of the predetermined part is lung respiratory motion, and the index value is a value indicating the vertical position of the diaphragm in the chest dynamic image.

The invention according to claim 5 is the invention according to any one of claims 1 to 3,
The predetermined periodical motion is a heart beat, and the index value is either a value indicating a heart wall position in the chest dynamic image or a pixel signal value of the aortic arch or pulmonary artery.

The invention according to claim 6 is the invention according to claim 3,
The chest dynamic image is an image taken during breathing,
The image analysis means includes an index that changes from the chest dynamic image in accordance with a phase delay time of a time change of the pixel signal value of each region with respect to a time change of an index value indicating respiratory motion of the lungs and a heart beat. Calculating the phase delay time of the time change of the pixel signal value of each region with respect to the time change of the value,
The display means displays each phase delay time calculated for each region.

The program of the invention described in claim 7 is:
Computer
Obtaining an index value indicating a periodic movement of a predetermined part from a chest dynamic image, calculating a time change of the index value, dividing a lung field region included in the chest dynamic image into a plurality of regions, Image analysis means for calculating a time change of a pixel signal value in each divided area and calculating a phase delay time of a time change of the pixel signal value in the area with respect to a time change in the index value for each area;
Display means for displaying the phase delay time calculated for each region;
To function as.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible for a doctor to identify easily the location where the ventilation function of a lung and the pulmonary blood flow function have fallen from the chest dynamic image.

It is a figure which shows the whole structure of the dynamic image diagnosis assistance system in embodiment of this 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 image analysis process performed by the control part of the diagnostic console of FIG. It is a flowchart which shows the ventilation analysis process performed in step S11 of FIG. It is a figure which shows the frame image of the several time phase T (T = t0-t6) image | photographed in one respiration cycle. It is a figure for demonstrating each part used at the time of the calculation of the distance of the lung apex and the perpendicular direction of a diaphragm. It is a figure which shows the example of the small block which divided | segmented the lung field area | region. It is a figure which shows the time change of the vertical position of a diaphragm, the time change of the average signal value of a certain small block, and a phase delay time. It is a figure which shows an example of the delay degree map etc. with respect to the time change of the up-and-down position of the diaphragm displayed on the display part of the diagnostic console of FIG. It is a flowchart which shows the pulmonary blood flow analysis process performed in step S12 of FIG. It is a figure for demonstrating each part used at the time of calculation of a heart wall position. It is a figure for demonstrating calculation of the reference position of a heart wall position. It is a figure which shows the time change of the heart wall position, the time change of the average signal value of a certain small block, and a phase delay time. It is a figure which shows an example of the delay degree map etc. with respect to the time change of the heart wall position displayed on the display part of the diagnostic console of FIG. It is a figure which shows typically an aortic arch and a pulmonary artery.

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

[Configuration of Dynamic Image Diagnosis Support System 100]
First, the configuration will be described.
FIG. 1 shows the overall configuration of a dynamic image diagnosis support system 100 in the present embodiment.
As shown in FIG. 1, in the dynamic image diagnosis support 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). ) Or the like via a communication network NT. Each device constituting the dynamic image diagnosis support 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 apparatus 1 is an apparatus that images the dynamics of the chest with periodicity (cycle), such as pulmonary expansion and contraction morphological changes, heart pulsation, and the like accompanying respiratory motion. Dynamic imaging is performed by continuously irradiating a human chest with radiation such as X-rays to acquire a plurality of images (that is, continuous imaging). A series of images obtained by this continuous shooting is called a dynamic image. Each of the plurality of images constituting the dynamic image is called a frame image.
As shown in FIG. 1, the imaging apparatus 1 includes a radiation source 11, a radiation irradiation control device 12, a radiation detection unit 13, a reading control device 14, a cycle detection sensor 15, a cycle detection device 16, and the like.

The radiation source 11 irradiates the subject M with radiation (X-rays) under 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, imaging start / end timing, X-ray tube current value, X-ray tube voltage value, filter type at the time of continuous irradiation. Etc. 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 the time from the start of one radiation irradiation to the start of the next radiation irradiation in continuous imaging, and coincides with a frame interval described later.

  The radiation detection unit 13 is configured by a semiconductor image sensor such as an FPD. 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 pixels to be converted and stored are arranged in a matrix. Each pixel includes a switching unit such as a TFT (Thin Film Transistor).

  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. 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 in continuous shooting, 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.

  The cycle detection sensor 15 detects the respiratory motion state of the subject M and outputs detection information to the cycle detection device 16. As the cycle detection sensor 15, for example, a respiration monitor belt, a CCD (Charge Coupled Device) camera, an optical camera, a spirometer, or the like can be applied.

  Based on the detection information input by the cycle detection sensor 15, the cycle detection device 16 determines the number of respiratory cycles and the state during one cycle of the current respiratory motion (for example, inspiration, inspiration to expiration conversion point, The state of the conversion point of exhalation and exhalation to inspiration is detected, and the detection result (cycle information) is output to the control unit 21 of the imaging console 2. The cycle detection device 16 receives, for example, detection information indicating that the state of the lung is a conversion point from inspiration to expiration by a cycle detection sensor 15 (respiration monitor belt, CCD camera, optical camera, spirometer, etc.). The timing is set as the base point of one cycle, and the period until the next timing when this state is detected is recognized as one cycle.

[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. Displayed for confirmation of whether the image is suitable for confirmation of positioning or diagnosis.
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 shooting control processing program for executing the shooting control process shown in FIG. In addition, the storage unit 22 stores radiation irradiation conditions and image reading conditions in association with the examination target region. 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 diagnosis console 3 is a moving image processing apparatus that acquires a dynamic image from the imaging console 2, displays the acquired dynamic image, and makes a diagnostic interpretation by a doctor.
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 out the system program and various processing programs stored in the storage unit 32 in accordance with the operation of the operation unit 33 and expands them in the RAM, and performs image analysis described later according to the expanded programs. Various processes including the process are executed to centrally control the operation of each part of the diagnostic console 3. The control unit 31 implements an image analysis unit by executing an image analysis process described later.

  The storage unit 32 is configured by a nonvolatile semiconductor memory, a hard disk, or the like. The storage unit 32 stores data such as parameters necessary for execution of processing or data such as processing results by various programs and programs including an image analysis processing program for executing image analysis processing by the control unit 31. 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.

  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 control unit 33 controls an instruction signal input by key operation or mouse operation on the keyboard. To 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 as a display unit is configured by a monitor such as an LCD or a CRT, and displays an input instruction, data, or the like from the operation unit 33 in accordance with a display signal instruction 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 Diagnosis Support System 100]
Next, the operation in the dynamic image diagnosis support system 100 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 photographing control processing program stored in the control unit 21 and the storage unit 22.

  First, the operation unit 23 of the imaging console 2 is operated by the imaging engineer, and patient information (patient name, height, weight, age, sex, etc.) of the imaging target (subject M) is 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). The frame rate (pulse rate) is preferably 5 frames / second or more. Normally, the delay time difference between the ventilation in the lung field and the pulmonary blood flow is 1 second or less. Therefore, to accurately express the phase delay time (detailed later) in a plurality of stages (at least 5 stages), 5 This is because it requires more than frames / second.

  Next, the radiation irradiation instruction by the operation of the operation unit 23 is waited. When the radiation irradiation instruction is input by the operation unit 23 (step S3; YES), the cycle detection start instruction is output to the cycle detection device 16, and the cycle The detection of the respiratory motion of the subject M by the detection sensor 15 and the cycle detection device 16 is started (step S4). When the cycle detection device 16 detects a predetermined state (for example, a conversion point from inspiration to expiration), an imaging start instruction is output to the radiation irradiation control device 12 and the reading control device 14, and dynamic imaging starts. (Step S5). 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 the cycle detecting device 16 detects a predetermined number of dynamic cycles, the control unit 21 outputs an instruction to end imaging to the radiation irradiation control device 12 and the reading control device 14, and the imaging operation is stopped.

  Frame images obtained by shooting are sequentially input to the shooting console 2, stored in the storage unit 22 in association with numbers indicating the shooting order (step S6), and displayed on the display unit 24 (step S7). . The imaging engineer confirms the positioning and the like based on 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 that the shooting is OK is input by a predetermined operation of the operation unit 23 (step S8; YES), an identification ID for identifying the dynamic image or each of a series of frame images acquired by the dynamic shooting is displayed. Information such as patient information, examination target part, radiation irradiation condition, image reading condition, imaging order number, cycle information, etc. are attached (for example, written in the header area of image data in DICOM format) To the diagnostic console 3 (step S9). 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 S8; NO), a series of frame images stored in the storage unit 22 is deleted (step S10), and this processing is performed. finish.

(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, it cooperates with the control unit 31 and the image analysis processing program stored in the storage unit 32. As a result, the image analysis processing shown in FIG. 3 is executed.

  In the image analysis process, a ventilation analysis process is first executed (step S11).

  FIG. 4 shows a flow of ventilation analysis processing. The ventilation analysis process is executed in cooperation with the control analysis unit 31 and the ventilation analysis process program stored in the storage unit 32.

  First, the temporal change in the vertical position of the diaphragm is calculated from the dynamic image (step S101).

  The diaphragm promotes the respiratory motion of the lungs by its vertical movement. FIG. 5 shows frame images of a plurality of time phases T (T = t0 to t6) taken in one respiratory cycle. As shown in FIG. 5, the respiratory cycle is composed of an expiration period and an inspiration period. In the exhalation period, air is exhausted from the lungs by raising the diaphragm, and the area of the lung field is reduced as shown in FIG. At the maximum expiratory position, the diaphragm is in the highest position. During the inspiration period, air is taken into the lungs as the diaphragm descends, and the lung field region in the thorax increases as shown in FIG. At the maximum inspiratory position, the diaphragm is in the lowest position. Thus, in the chest dynamic image, the change in the vertical position of the diaphragm becomes an index value indicating the respiratory motion of the lungs.

  Here, as can be seen from FIG. 5, the vertical position of the lung apex is hardly affected by the respiratory motion, and its position is hardly changed. Therefore, the vertical distance D between the lung apex and the diaphragm (see FIG. 6) is It can be said that it represents the vertical position of the diaphragm. Therefore, by calculating the vertical distance D between the lung apex and the diaphragm of each frame image of the dynamic image, it is possible to acquire the temporal change of the vertical position of the diaphragm.

For example, in step S101, first, the following processing is performed for each frame image.
First, extraction of the lung field region R of the left lung field and the right lung field shown in FIG. 6 is performed. Since the lung field region R has a large amount of radiation (X-ray) transmission, the pixel signal value (density value; hereinafter referred to as signal value) is higher than the surrounding region. Therefore, first, a density histogram is created from the signal value of each pixel of the frame image, and a threshold value is obtained by discriminant analysis or the like. Next, a region having a signal higher than the obtained threshold is extracted as a candidate for the lung region R. Next, edge detection is performed near the boundary of the candidate area, and a point where the edge is maximum in a small area near the boundary is extracted along the boundary. Then, the boundary line of the lung field region R is obtained by approximating the extracted edge point with a polynomial function.
When the lung field region R is extracted, the lung apex and diaphragm reference positions P1 and P2 are specified from the left and right lung field regions R. For example, the reference position P1 of the pulmonary apex is defined in advance as the position of the uppermost end of the lung field region R, and the reference position P1 of the pulmonary apex is extracted by extracting the position at the uppermost position in the vertical direction in the lung field region R. Identify. Further, the reference position P2 of the diaphragm is defined in advance as an average position in the vertical direction of the diaphragm curve C (shown by a dotted line in FIG. 6), and the diaphragm curve C is extracted from the lung field region R, The average position is obtained, and the obtained position is specified as the reference position P2 of the diaphragm. Then, a distance D between the vertical position (Y coordinate) of the identified reference position P1 of the lung apex and the reference position P2 of the diaphragm is calculated.

When the vertical distances D of P1 and P2 in the left lung field and the right lung field are calculated from each frame image of the dynamic image, the temporal change of the distance D indicates the vertical position of the diaphragm as an index value indicating respiratory motion Is obtained as a time change.
In FIG. 8, the time change of the vertical position of the diaphragm acquired from the dynamic image is shown by a dotted line. In FIG. 8, the horizontal axis represents the elapsed time t from the start of dynamic imaging, and the vertical axis represents the distance D.

Next, a time change period T0 and an angular frequency ω0 of the upper and lower positions of the diaphragm are calculated (step S102).
In step S102, for example, the time from the maximum value (peak) of the distance D between the lung apex and the diaphragm to the next maximum value (peak) is calculated as the period T0. The angular frequency ω0 is calculated by ω0 = 2π / T0.

  Next, warping processing (nonlinear distortion conversion processing) is performed on each frame image, and alignment of the lung field region R is performed between the frame images (step S103). In step S103, for example, a plurality of points (landmarks) having the same anatomical feature position are extracted from each frame image, and each landmark from the reference image is set with the first frame image taken as the reference image. The point shift value is calculated. Then, based on the calculated shift value of each point of the landmark, the shift value of all pixels is calculated using an approximation process of a six-dimensional polynomial, and an image is generated by shifting each pixel by the calculated shift value. To do.

  Next, the lung field region R of each frame image is divided into a plurality of regions (small blocks A1), and the average signal value (density average value) of the pixels in each small block A1 is calculated (step S104). For example, as shown in FIG. 7, the rectangular area circumscribing the lung field area R is divided into 0.4 to 4 cm square small blocks A1, and the average signal value of the pixels is calculated for each block.

Next, the time change of the calculated average signal value is calculated for each small block A1 (step S105).
In FIG. 8, the time change of the average signal value of a certain small block A1 is shown by a solid line. In FIG. 8, the horizontal axis indicates the elapsed time t from the start of dynamic imaging, and the vertical axis indicates the average signal value of the pixels in the small block A1. The signal value of the lung field in the radiation (X-ray) image is determined by the amount of X-ray transmission through the lung field, and the amount of X-ray transmission varies depending on the expansion and contraction of the lung. Therefore, the signal value in a certain area of the lung field is changing. This means that the amount of air contained in the alveoli in that area has changed with the expansion and contraction of the lung, that is, the ventilation volume has changed. The change in the average signal value of each small block A1 has a correlation with the change in the ventilation amount in the small block A1.

Next, for each small block A1, the phase delay time of the time change of the average signal value with respect to the time change of the upper and lower positions of the diaphragm (time change of the index value) is calculated (step S106).
The phase delay time in step S106 can be calculated by a time delay time calculation method using Fourier series expansion.
First, the phase change phase α1 of the index value and the time change phase α2 of the average signal value of each small block A1 are calculated. The phase α1 is calculated by the following [Equation 1].
The phase α2 can be calculated by replacing x (t) in α1 with the average signal value of the small block A1 at time t.
When the phases α1 and α2 are calculated, the phase delay time αT of the time change of the average signal value of each small block A1 with respect to the time change of the index value is calculated. αT is calculated by the following [Equation 2].

  Alternatively, the phase delay time in step S106 can be calculated by cross-correlation. In calculating the phase delay time based on cross-correlation, first, the time change of the average signal value of each small block A1 is filtered by a low-pass filter in the time direction (for example, cutoff frequency 0.5 Hz). Next, a cross-correlation value between the temporal change in the vertical position of the diaphragm as the index value and the temporal change in the average signal value of each small block A1 after filtering is calculated. Then, the time when the cross-correlation value is maximized is calculated as the phase delay time αT of each small block A1.

  According to the calculation method of step S106 described above, the phase delay time is calculated by extracting the pixel signal component having substantially the same frequency as the temporal change in the upper and lower positions of the diaphragm, so the time of the average signal value of each small block A1 Only the information about the ventilation volume can be extracted from the change, the influence of the pulmonary blood flow can be removed, and the phase delay time of the ventilation volume can be calculated with high accuracy.

  Then, a luminance value corresponding to the phase delay time of each small block A1 is calculated, and a delay degree map M1 in which each small block A1 of the reference image is displayed with the calculated luminance value is displayed on the display unit 34 (step 34). S107).

Further, the threshold value of the phase delay time of each small block A1 is read from the storage unit 32, and the ventilation of each small block A1 is determined depending on whether or not the phase delay time of each small block A1 calculated in step S106 exceeds the threshold value. It is determined whether or not the function is abnormal (step S108). The storage unit 32 stores a threshold value corresponding to the distance from the position specified as the reference position P2 of the diaphragm. In step S108, the distance from the reference position P2 is calculated for each small block A1, and it is determined whether or not the threshold corresponding to the calculated distance is exceeded.
Then, the abnormality determination result M2 in which the small block A1 determined to be abnormal in the above-described reference image is displayed in a color different from the other blocks is displayed side by side on the delay degree map M1 (step S109).

FIG. 9 shows an example of the delay degree map M1 and the abnormality determination result M2 displayed on the display unit 34. In FIG. 9, a standard delay degree map M0 is displayed together with M1 and M2. The standard delay degree map shows the phase delay time of the time change of the average signal value of each small block A1 with respect to the time change of the upper and lower positions of the diaphragm in a normal lung field. This standard delay degree map M0 is created based on a plurality of dynamic images obtained by photographing normal lung fields.
In the standard delay degree map M0 and the delay degree map M1 in FIG. 9, white (maximum luminance value) indicates that there is no delay from the temporal change in the upper and lower positions of the diaphragm, which is an index value of respiratory motion, and for a predetermined millisecond (for example, (33 milliseconds) Every time there is a delay, the brightness value is displayed by one step down.

  In the lung field, the respiratory movement is promoted by the vertical movement of the diaphragm and ventilation is performed. Therefore, as shown in the standard delay degree map M0 in FIG. 9, the change in the ventilation amount of each small block A1 according to the distance from the diaphragm. The phase delay time of the time change of the average signal value indicating is different. However, if the ventilation function is normal, the degree of phase delay is substantially constant according to the distance from the diaphragm. However, if there is a part where the ventilation function is abnormal in the lung field region, the phase delay of that part becomes large. Therefore, as shown in FIG. 9, the standard delay degree map M0 and the delay degree map M1 obtained by dynamic imaging of the subject M are displayed side by side, so that the ventilation function can be locally performed in the lung field of the subject M. It becomes possible for a doctor to easily identify a portion where the drop is low. In addition, by displaying the small block A1 having a phase delay time larger than a predetermined threshold value in a different color in the abnormality determination result M2, the doctor can more easily identify the abnormal part where the ventilation function is locally reduced. It becomes possible to do. By displaying the delay degree map M1 and the abnormality determination result M2, the doctor can easily recognize, for example, when there is chronic obstructive pulmonary disease (COPD), interstitial pneumonia, pneumothorax, and the like. According to the delay degree map M1 in FIG. 9, it can be seen that the subject M is suspected of being abnormal due to pneumothorax or the like in the upper left lung field.

  When the operation unit 33 instructs the shift to the pulmonary blood flow analysis, the process shifts to step S12 in FIG. 3 and the pulmonary blood flow analysis process is executed (step S12).

  FIG. 10 shows a flow of pulmonary blood flow analysis processing. This process is realized by cooperation between the control unit 31 and the pulmonary blood flow analysis processing program stored in the storage unit 32.

First, the time change of the heart wall position of the left ventricle is calculated from the dynamic image (step S201).
Since the position of the heart wall changes depending on the heart beat, in the chest dynamic image, the time change of the heart wall position can be used as an index value indicating the heart beat.

For example, in step S201, first, the following processing is performed for each frame image.
First, extraction of the lung field R of the left lung field and the right lung field shown in FIG. 11 and the specification of the position P1 of the lung apex in the left lung field are performed.
Next, the heart region H is recognized. In the recognition of the heart region H, first, the search region is limited from the circumscribed rectangular region of the lung field region R. Next, a density histogram is created from the signal value of each pixel in the search region, a threshold value is obtained by a discriminant analysis method or the like, and a region having a signal lower than the threshold value is extracted as a candidate region for the heart. Next, edge detection is performed within the candidate region, and the contour line of the heart region is extracted by tracking the maximum value of the differential value greater than or equal to a predetermined size. At this time, the contour edge point search region is limited based on the shape of the approximate heart region so as not to track the background or the edge inside the heart. Then, template matching is performed on the extracted contour image of the heart region using a heart contour template, and the template region at the position where the correlation value is maximized is recognized as the heart region H.
Next, the reference position P3 of the heart wall of the left ventricle is specified. For example, the leftmost edge point of the heart region H whose vertical direction is a predetermined distance from the lung apex reference position P1 is specified as the heart wall reference position P3. Since the gently curved portion of the left edge of the heart region H corresponds to the left ventricle, the gradient of the heart edge with respect to the vertical coordinate (Y coordinate) (the absolute value of the inclination (in FIG. 12) from top to bottom. (Absolute value of ΔX / ΔY) is determined, and the position of the point at which the distance from the lung apex becomes equal to or greater than the predetermined threshold is determined as the reference position P3 of the heart wall only after the gradient becomes equal to or less than the predetermined threshold. May be.

When the position of P3 is specified from each frame image of the dynamic image, the temporal change of the heart wall position is calculated based on the horizontal position of P3 (the X coordinate of P3) of each frame image.
FIG. 13 shows a time change of the heart wall position calculated from the dynamic image by a dotted line. In FIG. 13, the horizontal axis indicates the elapsed time t from the start of dynamic imaging, and the vertical axis indicates the horizontal position of the reference position P3 of the heart wall.

Next, the time change period T0 and the angular frequency ω0 of the heart wall position are calculated (step S202).
In step S202, for example, the time from the maximum value (peak) of the heart wall position to the next maximum value (peak) is calculated as the period T0. The angular frequency ω0 is calculated by ω0 = 2π / T0.

  Next, warping processing (nonlinear distortion conversion processing) is performed on each frame image, and alignment of the lung field region R is performed between the frame images (step S203). The process in step S203 is the same as the process in step S103.

  Next, the lung field region R of each frame image is divided into small blocks A1, and the average signal value (density average value) of the pixels in each small block A1 is calculated (step S204). For example, a rectangular region circumscribing the lung field region R is divided into small blocks A1 each having a size of 0.4 to 4 cm square, and an average signal value of pixels is calculated for each block.

Next, the time change of the calculated average signal value is calculated for each small block A1 (step S205).
In FIG. 13, the time change of the average signal value of a certain small block A1 is shown by a solid line. In FIG. 13, the horizontal axis represents the elapsed time t from the start of dynamic imaging, and the vertical axis represents the average signal value of the pixels in the small block A1. The signal value of the lung field in the radiation (X-ray) image varies depending on the pulmonary blood flow generated by the heart beat. Therefore, the change in the average signal value of each small block A1 is correlated with the change in the pulmonary blood flow in the small block A1.

Next, for each small block A1, the phase delay time of the time change of the average signal value with respect to the time change of the heart wall position (time change of the index value) is calculated (step S206).
The phase delay time in step S206 can be calculated by, for example, a time delay time calculation method by Fourier series expansion shown in the above [Equation 1] and [Equation 2]. Alternatively, the phase delay time can be calculated by cross-correlation. In the calculation of the phase delay time based on the cross-correlation, first, the time change of the heart wall position is filtered with a high-pass filter in the time direction (for example, a cutoff frequency of 0.7 Hz). Further, the temporal change of the average signal value of each small block A1 is filtered by a high-pass filter in the time direction (for example, a cutoff frequency of 0.7 Hz). Next, a cross-correlation value between the temporal change of the heart wall position after filtering and the temporal change of the average signal value of each small block A1 after filtering is calculated. Then, the time when the cross-correlation value is maximum is calculated as the phase delay time of each small block A1.

  According to the calculation method of step S206 described above, since the phase delay time is calculated by extracting pixel signal components having substantially the same frequency as the time change of the heart wall position, the time change of the average signal value of each small block A1. Thus, only the information about the pulmonary blood flow can be taken out, the influence of ventilation (respiration) can be removed, and the phase delay time of the pulmonary blood flow can be calculated with high accuracy. Further, it is not necessary to hold the breath for pulmonary blood flow analysis during dynamic imaging. In addition, when dynamic imaging is performed with the breath held, there is no need for filtering because there is no influence of breathing.

  Then, a luminance value corresponding to the phase delay time of each small block A1 is calculated, and a delay degree map M11 in which each small block A1 of the reference image is displayed with the calculated luminance value is displayed on the display unit 34 (step 34). S207).

Further, the threshold value of the phase delay time of each small block A1 is read from the storage unit 32, and the lung of each small block A1 is determined depending on whether or not the phase delay time of each small block A1 calculated in step S206 exceeds the threshold value. It is determined whether or not the blood flow function is abnormal (step S208). The storage unit 32 stores a threshold value of the phase delay time corresponding to the distance from the center of the heart. In step S208, for each small block A1, the distance from the center of the heart (for example, the center of the circumscribed circle of the heart region H) is calculated, and whether or not the threshold corresponding to the calculated distance is exceeded. Is judged.
Then, the abnormality determination result M12 in which the small block A1 determined to be abnormal in the above-described reference image is displayed in a color different from the other blocks is displayed side by side on the delay degree map M11 (step S209).

FIG. 14 shows an example of the delay degree map M11 and the abnormality determination result M12 displayed on the display unit 34. In FIG. 14, a standard delay degree map M10 is displayed together with M11 and M12. The standard delay degree map M10 shows the phase delay time of the time change of the average signal value of each small block A1 with respect to the time change of the heart wall position, which is an index value of the heart beat, in the normal lung field. . The standard delay degree map M10 is created based on a plurality of dynamic images obtained by photographing normal lung fields.
In the standard delay degree map M10 and the delay degree map M11 of FIG. 14, the phase delay time of each small block A1 is displayed in luminance, but white (maximum luminance value) is a heart wall that is an index value of heart beat. This indicates that there is no delay from the time change, and the luminance value is displayed by one step down every predetermined millisecond (for example, 33 milliseconds).

  In the lung field, blood is pushed out from the heart by the pulsation of the heart, and this blood flows through the blood vessels in each part of the lung field. Therefore, as shown in the standard delay degree map M10 in FIG. 14, it depends on the distance from the center of the heart. The phase lag of the time change of the average signal value indicating the pulmonary blood flow in each small block A1 differs. However, the degree of the phase delay is substantially constant according to the distance from the heart if the pulmonary blood flow function is normal. However, if there is a part where the pulmonary blood flow function is abnormal in the lung field region, the phase delay of that part becomes large. Therefore, as shown in FIG. 14, the pulmonary blood flow function is locally reduced by displaying the standard delay degree map M10 and the delay degree map M11 obtained by dynamic imaging of the patient side by side. The location can be easily identified by the doctor. In addition, by displaying, in the abnormality determination result M12, the small block A1 having a phase delay time larger than a predetermined threshold value in a different color, it is easier for a doctor to identify an abnormal location where the pulmonary blood flow function is locally reduced. Can be identified. By displaying the delay degree map M11 and the abnormality determination result M12, for example, when there is a lesion such as pulmonary thromboembolism or pulmonary infarction, the doctor can easily recognize it. According to the delay degree map M2 in FIG. 14, it can be seen that the subject M is suspected of having an abnormality in the right lung field due to pulmonary thromboembolism or the like.

  In the above pulmonary blood flow analysis processing, the heart wall position is used as an index value indicating the heart beat, and the phase delay time of the time change of the average signal value of each small block A1 with respect to the time change of the heart wall position is represented by the luminance. Although the display is based on the value or the like, the index value indicating the pulsation of the heart is not limited to this. For example, the signal value of the aortic arch or pulmonary artery in the dynamic image is used as an index value indicating the pulsation of the heart. It is good also as displaying by.

FIG. 15 schematically shows the aortic arch and pulmonary artery in the chest image.
As shown in FIG. 15, the aortic arch is usually seen slightly above the center on the left lung field mediastinum side on the chest front X-ray image, and appears as a shadow curved in a convex shape to the left. The position can be recognized by extracting an edge from the chest front X-ray image (that is, each frame image) and performing template matching using the template of the aortic arch shadow. An ROI (Region Of Interest) is set in the recognized aortic arch shadow, and the average signal value in the ROI is used as an index value indicating the pulsation of the heart.
The left pulmonary artery is located slightly below the aortic arch in the left lung field and is included in the shadow of a white pattern called pulmonary pattern. Among them, the thick artery protrudes slightly to the left from the mediastinum and runs downward Appears as a shadow. Similar to the aortic arch, the position can be recognized by extracting the edge and performing template matching using the thick artery shadow template. An ROI is set in a portion of the recognized left pulmonary artery shadow as close to the mediastinum as possible, and an average signal value in the ROI is used as an index value indicating the heartbeat.

  The aortic arch is the main trunk of the artery that pumps blood from the left ventricle of the heart to the whole body, and the pulmonary artery is the artery that pumps blood from the right ventricle to the lung, and each signal value shows the heartbeat significantly It is. In observing pulmonary blood flow, it is preferable to extract the signal value change on the pulmonary artery, but the pulmonary artery is difficult to identify because the shadow is pale compared to the aortic arch, and it may be hidden in the heart, so in image processing The signal value of the aortic arch is preferably used as an index value of the heart beat.

  Note that the processing results of the image analysis processing (the phase delay time and the abnormality determination result of each small block A1) are preferably stored in the storage unit 32 in association with the dynamic image. This is because it is not necessary to perform image analysis processing when the dynamic image is read next.

  As described above, according to the diagnostic console 3 according to the present invention, the control unit 31 acquires the vertical position of the diaphragm from each frame image of the dynamic image of the chest transmitted from the imaging console 2, and While calculating the temporal change of the vertical position, dividing the lung field region of each frame image of the dynamic image into a plurality of small blocks A1, calculating the temporal change of the pixel signal value in each of the divided small blocks A1, For the small block A1, the phase delay time of the temporal change of the pixel signal value in the small block with respect to the temporal change of the vertical position of the diaphragm is calculated. Each small block A1 is displayed on the display unit 34 with a luminance value corresponding to the phase delay time.

  Therefore, in the lung field, it is displayed how the phase delay time of the time change of the signal value indicating the ventilation volume is distributed with respect to the time change of the vertical position of the diaphragm, which is an index of the respiratory motion of the lung. When there is a place where the ventilation function of the lung is lowered, the doctor can easily identify it.

  Further, the control unit 31 determines whether or not the ventilation function of each small block A1 is abnormal based on whether or not the calculated phase delay time of each small block A1 exceeds a predetermined threshold value, Since the determination result is displayed on the display unit 34, it becomes possible for the doctor to more easily recognize an abnormal portion where the lung ventilation function is reduced. Further, since the respiratory motion of the subject M is used as a reference, an abnormality in the ventilation function of each block is determined depending on how much the signal value of each block in the lung field changes with respect to the reference. Therefore, it is possible to make an abnormality determination with high accuracy.

  In calculating the phase lag time, the pixel lag component is extracted by extracting the pixel signal component having substantially the same frequency as the temporal change in the upper and lower positions of the diaphragm, so only the information on the ventilation volume is extracted from the dynamic image, and the pulmonary blood flow The phase delay time can be calculated with high accuracy.

  In addition, the control unit 31 of the diagnostic console 3 obtains the heart wall position from each frame image of the chest dynamic image transmitted from the imaging console 2 and calculates the temporal change of the heart wall position. The lung field region of each frame image is divided into a plurality of small blocks A1, the temporal change of the pixel signal value in each of the divided small blocks A1 is calculated, and the small block with respect to the temporal change of the heart wall position is calculated for each small block A1. The phase delay time of the time change of the pixel signal value in the block is calculated. Each small block A1 is displayed on the display unit 34 with a luminance value corresponding to the phase delay time.

  Therefore, in the lung field, it is displayed how the phase delay time of the time change of the signal value indicating the pulmonary blood flow is distributed with respect to the time change of the heart wall position as an index of the heart beat. When there is a portion where the pulmonary blood flow function is lowered, the doctor can easily identify it.

  Further, the control unit 31 determines whether or not the pulmonary blood flow function of each small block A1 is abnormal based on whether or not the calculated phase delay time of each small block A1 exceeds a predetermined threshold value. And since a judgment result is displayed on the display part 34, it becomes possible for a doctor to recognize the abnormal location where the pulmonary blood flow function has fallen more easily. In addition, since the heart beat of the subject M is used as a reference, an abnormality in the pulmonary blood flow function of each block is determined depending on how much the signal value of each block in the lung field changes with respect to the reference. Therefore, it is possible to accurately determine an abnormality in consideration of individual differences in pulsation.

  In calculating the phase lag time, the pixel lag component is extracted by extracting the pixel signal component of approximately the same frequency as the time change of the heart wall position, so only the information on the pulmonary blood flow is extracted from the dynamic image, and the influence of ventilation Therefore, the phase delay time can be calculated with high accuracy. Further, it is not necessary for the subject M to hold his or her breath during shooting.

  Further, in the image analysis processing, the phase delay time of the time change of the average signal value of each small block A1 with respect to the time change of the vertical position of the diaphragm and the time change of the heart wall position from the dynamic image of the chest taken during breathing Since the phase lag time of the time change of the average signal value of each small block A1 with respect to each is calculated and the respective phase lag times calculated for each small block A1 are displayed on the display unit 34, respectively, It becomes possible to analyze both the ventilation function and the pulmonary blood flow function.

In addition, the description in this Embodiment mentioned above is an example of the suitable dynamic image diagnosis assistance system which concerns on this invention, and is not limited to this.
For example, in the above-described embodiment, the standard delay degree maps M0 and M10 and the delay degree maps M1 and M11 are displayed with luminance values corresponding to the phase delay time, but are displayed in a color corresponding to the phase delay time. It is good as well.

  In the above embodiment, the case where both the ventilation function and the pulmonary blood flow function are analyzed has been described as an example. However, the function to be analyzed may be selected by operating the operation unit 33. .

For example, in the above description, an example in which a hard disk, a semiconductor non-volatile 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 other computer-readable media, a portable recording medium such as a CD-ROM can be applied. Further, 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 diagnosis support system 100 can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 Dynamic image diagnosis support system 1 Imaging device 11 Radiation source 12 Radiation irradiation control device 13 Radiation detection unit 14 Reading control device 15 Cycle detection sensor 16 Cycle detection device 2 Imaging console 21 Control unit 22 Storage unit 23 Operation unit 24 Display unit 25 Communication unit 26 Bus 3 Diagnosis console 31 Control unit 32 Storage unit 33 Operation unit 34 Display unit 35 Communication unit 36 Bus

Claims (7)

Obtaining an index value indicating a periodic movement of a predetermined part from a chest dynamic image, calculating a time change of the index value, dividing a lung field region included in the chest dynamic image into a plurality of regions, Image analysis means for calculating a temporal change of a pixel signal value in each divided area and calculating a phase delay time of a temporal change in the pixel signal value in the area with respect to a temporal change in the index value for each area;
Display means for displaying the phase delay time calculated for each region;
A dynamic image processing apparatus comprising: The image analysis means determines whether or not the function of each region is abnormal based on whether or not the phase delay time calculated for each region exceeds a predetermined threshold,
The dynamic image processing apparatus according to claim 1, wherein the display unit displays a determination result for each region.   The said image analysis means calculates the said phase delay time by extracting the pixel signal component of the frequency substantially the same as the time change of the index value which shows the periodic motion of the said predetermined part about each said area | region. 2. The dynamic image processing apparatus according to 2.   The dynamic image according to any one of claims 1 to 3, wherein the cyclic motion of the predetermined part is a respiratory motion of the lung, and the index value is a value indicating a vertical position of the diaphragm in the chest dynamic image. Processing equipment.   The periodic motion of the predetermined part is a heart beat, and the index value is either a value indicating a heart wall position in the chest dynamic image or a pixel signal value of an aortic arch or a pulmonary artery. The dynamic image processing apparatus according to any one of 1 to 3. The chest dynamic image is an image taken during breathing,
The image analysis means includes an index that changes from the chest dynamic image in accordance with a phase delay time of a time change of the pixel signal value of each region with respect to a time change of an index value indicating respiratory motion of the lungs and a heart beat. Calculating the phase delay time of the time change of the pixel signal value of each region with respect to the time change of the value,
The dynamic image processing apparatus according to claim 3, wherein the display unit displays each phase delay time calculated for each region. Computer
Obtaining an index value indicating a periodic movement of a predetermined part from a chest dynamic image, calculating a time change of the index value, dividing a lung field region included in the chest dynamic image into a plurality of regions, Image analysis means for calculating a time change of a pixel signal value in each divided area and calculating a phase delay time of a time change of the pixel signal value in the area with respect to a time change in the index value for each area;
Display means for displaying the phase delay time calculated for each region;
Program to function as.