JP7547950B2 - Dynamic analysis device and program - Google Patents

Description

The present invention relates to a dynamic analysis device and program.

Various techniques have been proposed for obtaining information for diagnosing a subject's lungs by analyzing dynamic images showing the lung field.
For example, Patent Document 1 describes an image processing device that includes a difference means for generating a plurality of difference images indicating the difference in pixel values between a plurality of images that constitute a dynamic image of an object, and a display means for sequentially switching between and displaying the generated difference images.
Furthermore, Patent Document 2 describes a dynamic analysis device that includes an index value measuring means for measuring changes over time in index values relating to the position and shape of blood vessels in multiple regions within a dynamic image obtained by radiographing a part of a subject that includes blood vessels, an elongation rate calculating means for calculating the elongation rate of blood vessels in each region based on the changes over time in the index value of each measured region, and an elongation rate display means for displaying a list of the calculated elongation rates in each region.

Patent No. 4404291 JP 2019-058368 A

However, conventional image processing devices that capture changes in pixel values, such as those described in Patent Document 1, may produce artifacts A caused by movement or deformation of areas other than the lungs (e.g., ribs, breasts, fat, etc.) located around the lungs when quantifying (visualizing) the analysis results.
For example, it is known that when breathing in an upright position, the amount of ventilation in the upper lung fields is small.
However, when a dynamic image obtained by dynamic imaging of the chest of a subject in a standing position is analyzed using a dynamic analysis device that captures changes in pixel values, artifacts A due to movement or deformation of parts other than the lungs may occur in the upper lung field region. As a result, the information indicating the ventilation function output by this dynamic analysis device (dynamic image I with a conventional color map M _C superimposed thereon) may appear to have no or only a small difference between the upper lung field region and the middle and lower lung field regions, as shown in FIG.
Although it is relatively easy to remove ribs from dynamic images by performing image processing on the dynamic images, it is difficult to remove breasts and fat.

Furthermore, in order to accurately calculate the elongation rate using a conventional dynamic analysis device that captures changes in distance of blood vessels, such as that described in Patent Document 2, it is necessary to detect the blood vessels shown in the dynamic images with high accuracy (to avoid mistakenly identifying parts other than blood vessels as blood vessels).
However, detecting blood vessels with high accuracy from dynamic images is difficult and time-consuming, so when using this dynamic analysis device, the time between completing dynamic imaging and starting diagnosis becomes long.
In addition, dynamic analysis devices that capture changes in the distance of blood vessels cannot analyze the dynamics of peripheral areas where blood vessels do not exist or are so thin that they cannot be detected. For this reason, when using such dynamic analysis devices, it is difficult to obtain information showing the ventilation function of the entire lungs.

The present invention has been made in consideration of the above problems, and aims to make it possible to easily and in a relatively short time obtain information indicating the ventilation function of the entire lungs, without being affected by the movement or deformation of areas other than the lungs that are located around the lungs, when analyzing dynamic images obtained by dynamic imaging of the lungs of a subject.

In order to solve the above problems, a dynamic analysis device according to the present invention comprises:
a measuring means for specifying the positions of a plurality of evaluation points arranged in a lung field area captured in a frame in frames other than the frame by estimating where a small area of a specific density around the evaluation point will move in the next frame, calculating the distance between the plurality of evaluation points for each frame , and measuring the change over time in the distance between the plurality of evaluation points based on the distance between the plurality of evaluation points;
and an output means for outputting information indicating the ventilation function of the lungs of the subject based on the change over time in the distance between the evaluation points measured by the measurement means.
In addition, the dynamic analysis device according to the present invention comprises:
a measuring means for specifying the positions of a plurality of evaluation points arranged in a lung field area captured in a frame in frames other than the frame by estimating where a small area of a specific density around the evaluation point will move in the next frame, calculating the distance between the plurality of evaluation points for each frame , and measuring the change over time in the distance between the plurality of evaluation points based on the distance between the plurality of evaluation points;
and an output means for outputting information indicating a ventilatory function of the lungs of the subject based on a change over time in the distance between the evaluation points measured by the measurement means ,
The measurement means calculates the area of a polygon having vertices made up of three or more evaluation points arranged around a reference evaluation point for each group of evaluation points that have been divided in advance, and treats the area of the polygon as distance information for the group .

In addition, the program according to the present invention is
On the computer,
a measurement process for determining the positions of evaluation points arranged in a dynamic image consisting of a plurality of frames obtained by dynamic imaging of the lungs of a subject, the evaluation points being arranged in image data, in a frame other than the one frame , by estimating where a small area of a specific density around the evaluation points will move to in the next frame, calculating the distance between the plurality of evaluation points for each frame, and measuring the change over time in the distance between the plurality of evaluation points based on the distance between the plurality of evaluation points;
and an output process for outputting information indicating the ventilatory function of the lungs of the subject based on the change over time of the distance between the evaluation points measured in the measurement process.
In addition, the program according to the present invention is
On the computer,
a measurement process for determining the positions of evaluation points arranged in a dynamic image consisting of a plurality of frames obtained by dynamic imaging of the lungs of a subject, the evaluation points being arranged in image data, in a frame other than the one frame , by estimating where a small area of a specific density around the evaluation points will move to in the next frame, calculating the distance between the plurality of evaluation points for each frame, and measuring the change over time in the distance between the plurality of evaluation points based on the distance between the plurality of evaluation points;
an output process for outputting information indicating a ventilatory function of the lungs of the subject based on a change over time in the distance between the evaluation points measured in the measurement process ;
The measurement process calculates the area of a polygon whose vertices are three or more evaluation points arranged around a reference evaluation point for each group of evaluation points that have been divided in advance, and uses the area of the polygon as distance information for the group.

According to the present invention, when analyzing dynamic images obtained by dynamic imaging of the lungs of a subject, information indicating the ventilation function of the entire lungs can be obtained easily and in a relatively short time without being affected by the movement or deformation of areas other than the lungs that are located around the lungs.

1 is a block diagram showing an example of a radiation imaging system according to an embodiment of the present invention. FIG. 11 is a block diagram showing another example of a radiation imaging system according to an embodiment of the present invention. FIG. 3 is a block diagram showing a dynamic analysis device provided in the radiography system of FIGS. 4 is a flowchart showing a flow of a dynamic analysis process executed by the dynamic analysis device of FIG. 3 . FIG. 13 is a diagram showing a frame in which evaluation points are placed in a lung field region. FIG. 13 is a diagram showing a group G of multiple evaluation points. FIG. 13 is a diagram showing the movement of evaluation points accompanying the movement of the lung field region. FIG. 13 is a diagram illustrating an example of a method for calculating the amount of change in an area between evaluation points. FIG. 4 is a diagram showing an example of information indicating ventilation function output by the dynamic analysis device of FIG. 3 . FIG. 13 is a diagram showing information indicating ventilation function output by a conventional dynamic analysis device.

The present invention is based on the new finding that changes in distance between multiple evaluation points placed at any location within a lung field region captured in a dynamic image show a correlation with ventilation function.
"Ventilation" refers to the process in which the air in the alveoli flows out to the trachea and in from the trachea to the alveoli due to the contraction and expansion of the alveoli that accompanies breathing.
This fact has been confirmed by comparison with the results of clinical studies using pulmonary ventilation scintigraphy.

Embodiments of the present invention will be described below with reference to the drawings. However, the technical scope of the present invention is not limited to the following embodiments and illustrated examples.

<1. Radiography System>
First, a schematic configuration of a radiation imaging system (hereinafter, referred to as a system 100) according to this embodiment will be described.
FIG. 1 is a block diagram illustrating a system 100 .

As shown in FIG. 1, the system 100 includes a radiation imaging apparatus (hereinafter, referred to as imaging apparatus 1) and a console 2.
The system 100 according to this embodiment further includes a radiation generating device (hereinafter, a radiation generating device 3 ) and a dynamic analysis device 4 .
The devices 1 to 4 are capable of communicating with each other, for example, via a communication network N (such as a local area network (LAN), a wide area network (WAN), or the Internet).

The system 100 may be installed in an imaging room, or may be configured to be movable (for example, as a mobile cart).
Furthermore, the system 100 may be capable of communicating with a Hospital Information System (HIS), a Radiology Information System (RIS), or the like, which are not shown.

[1-1. Radiation Generator]
The generating device 3 includes a generator 31, an irradiation instruction switch 32, and a radiation source 33 (a tube).

Based on the operation of the irradiation instruction switch 32, the generator 31 applies a tube voltage according to the preset imaging conditions to the radiation source 33 and passes a tube current according to the imaging conditions to the radiation source 33.

When a tube voltage is applied from the generator 31 and a tube current flows, the radiation source 33 generates a dose of radiation X (e.g., X-rays) according to the applied tube voltage and the flowing tube current.

Moreover, the generating device 3 according to this embodiment is configured to generate radiation X in a manner that corresponds to the form of the radiation image to be generated (a still image, or a dynamic image made up of a plurality of frames).
In the case of a still image, radiation X is irradiated only once each time the irradiation instruction switch 32 is pressed.
In the case of dynamic images, each time the irradiation instruction switch 32 is pressed, irradiation of pulsed radiation X is repeated multiple times per predetermined time (for example, 15 times per second), or irradiation of radiation X is continued for a predetermined time.

[1-2. Radiography Equipment]
The imaging device 1 generates digital data of a radiation image showing an imaging region of a subject S.
The imaging device 1 according to this embodiment is a portable FPD (Flat Panel Detector).
Specifically, although not shown in the figures, the imaging device 1 according to this embodiment includes a sensor substrate on which image pickup elements that generate charges according to the dose when exposed to radiation X and switch elements that accumulate and release charges are arranged in a two-dimensional form (in a matrix), a scanning unit that switches each switch element on/off, a readout unit that reads out the amount of charge released from each pixel as a signal value, a control unit that controls each unit and generates a radiographic image from the multiple signal values read out by the readout unit, and a communication unit that transmits the generated radiographic image, various signals, etc. to other devices (the console 2, the generator 3, the dynamic analysis device 4, etc.) and receives various information, various signals, etc. from the other devices.

The imaging device 1 is adapted to generate still or dynamic images by storing and releasing electric charges and reading out signal values in synchronization with the timing at which radiation X is emitted from the generating device 3 .
When a still image is to be generated, a radiation image is generated only once for each depression of the irradiation instruction switch 32 .
When generating a dynamic image, the generation of frames constituting the dynamic image is repeated multiple times per predetermined time (for example, 15 times per second) for each depression of the irradiation instruction switch 32 .
Hereinafter, the operation of the imaging device 1 to generate dynamic images showing the imaging target part of the subject will be referred to as dynamic imaging.

The imaging device 1 may be integrated with the generating device 3 (for example, a CT (Computed Tomography) device, etc.).
Furthermore, the imaging device 1 may be configured to display the generated dynamic image in real time on a display device connected to the imaging device 1 (for example, to perform fluoroscopy).

[1-3. Console]
The console 2 sets various imaging conditions for at least one of the imaging device 1 and the generating device 3 .
The console 2 is composed of a PC, a dedicated device, and the like.
The imaging conditions include, for example, conditions related to the subject S (imaged part, imaging direction, physique, etc.) and conditions related to irradiation of radiation X (tube voltage, tube current, irradiation time, current-time product (mAs value), etc.).
The console 2 may set the shooting conditions automatically based on shooting order information obtained from another system (HIS, RIS, etc.), or may set the shooting conditions (manually) based on operations performed on the operation unit by a user (e.g., a technician, etc.).

[1-4. Dynamic analysis device]
The dynamic analysis device 4 analyzes the dynamic images generated by the imaging device 1, and outputs various information for assisting diagnosis (for example, information indicating the ventilation function of the lungs).
The dynamic analysis device 4 is composed of a PC, a dedicated device, and the like.
The dynamics analysis device 4 will be described in detail later.

[1-5. Shooting process]
The imaging of the subject S using the system 100 configured in this manner is carried out in the following manner.
First, a user (technologist, etc.) places the subject S between the radiation source 33 of the generating device 3 and the imaging device 1, which are arranged facing each other with a gap between them, and performs positioning.
When the user operates the irradiation instruction switch 32, the generator 3 irradiates the part of the subject S to be imaged with radiation X.
The imaging device 1 generates a radiation image (still image, dynamic image) showing the imaging region at the timing when the imaging device 1 receives radiation X from the generation device 3 .
When the generated radiation image is a dynamic image, the imaging device 1 transmits the dynamic image to the dynamic analysis device 4 directly or via the console 2 .
The dynamic analysis device 4 analyzes the dynamics of the imaging site of the subject S using the received dynamic images, and outputs various information (such as information indicating the ventilation function of the lungs).

[1-6. Other]
So far, the system 100 including the dynamic analysis device 4 has been described, but the dynamic analysis device 4 may also be another device constituting the system 100 (for example, the console 2).
Specifically, for example, as shown in FIG. 2, a radiation imaging system 100A may be configured by the imaging device 1, the generator 3, and a console 2A also serving as a dynamic analysis device.

2. Details of the dynamics analysis device
Next, details of the dynamic analysis devices 4, 2A included in the above-mentioned systems 100, 100A will be described using a single dynamic analysis device 4 as an example.
FIG. 3 is a block diagram showing the dynamic analysis device 4, FIG. 4 is a flowchart showing the flow of the dynamic analysis processing performed by the dynamic analysis device 4, FIG. 5 is a diagram showing a frame F in which an evaluation point P is placed in the lung field region R _L , FIG. 6 is a diagram showing a group G of multiple evaluation points P, FIG. 7 is a diagram showing the movement of the evaluation point P associated with the movement of the lung field region R _L , FIG. 8 is a diagram showing an example of a method for calculating the amount of change in the area between evaluation points P and evaluation points P, and FIG. 9 is a diagram showing an example of information indicating the ventilation function output by the dynamic analysis device 4 of this embodiment.

2-1. Configuration of dynamic analysis device
As shown in FIG. 3, the dynamic analysis device 4 includes a control unit 41, a storage unit 42, and a communication unit 43.
The dynamic analysis device 4 according to this embodiment further includes a display unit 44 and an operation unit 45 .
The units 41 to 45 are electrically connected to each other via a bus or the like.

The control unit 41 is composed of a CPU (Central Processing Unit), a RAM (Random Access Memory), and the like.
The CPU reads out various programs stored in the ROM, loads them into the RAM, executes various processes in accordance with the loaded programs, and centrally controls the operation of each part of the dynamic analysis device 4.

The storage unit 42 is composed of a non-volatile memory, a hard disk, and the like.
The storage unit 42 also stores various programs executed by the control unit 41, parameters required for executing the programs, and the like.
The storage unit 42 may be capable of storing radiation images acquired from other devices (the imaging device 1, the dynamic analysis device 4, etc.).
This is also fine.

The communication unit 43 is composed of a communication module and the like.
The communication unit 43 is configured to send and receive various signals, various data, etc. between other devices (the imaging device 1, the generating device 3, the dynamic analysis device 4, etc.) connected by wire or wirelessly via the communication network N.

The display unit 44 is composed of, for example, an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube), or the like.
The display unit 44 then displays a radiation image or the like in accordance with the image signal received from the control unit 41 .

The operation unit 45 can be operated by the user.
The operation unit 45 includes, for example, a keyboard (cursor keys, numeric input keys, various function keys, etc.), a pointing device (mouse, etc.), a touch panel laminated on the surface of the display unit 44, etc.
The operation unit 45 then outputs a control signal to the control unit 41 in accordance with the operation performed by the user.

The dynamic analysis device 4 may not include a display unit 44 and an operation unit 45, and may receive a control signal from an input device provided separately from the dynamic analysis device 4, for example, via a communication unit 43, or output an image signal to a display device (monitor) provided separately from the dynamic analysis device 4.

2-2. Operation of the dynamic analysis device
The control unit 41 of the behavior analysis device 4 configured as above is adapted to execute a behavior analysis process, for example, as shown in FIG. 4, when a predetermined condition is met.
The specified conditions include, for example, the power of the dynamic analysis device 4 being turned on, the imaging device 1 starting to generate and transmit a radiological image, receiving a specified control signal from another device, and performing a specified operation on the operation unit 45.

(Acquisition process)
In this dynamic analysis process, the control unit 41 first executes an acquisition process (step S1).
In this acquisition process, the control unit 41 acquires from the imaging device 1 a dynamic image I obtained by dynamic imaging of the imaging target part (lungs) of the subject.
In the acquisition process according to this embodiment, the control unit 41 acquires the dynamic image I data by having the communication unit 43 receive the dynamic image I data.
In addition, in this acquisition process, the control unit 41 may acquire the data of the dynamic image I stored in a storage medium (e.g., a USB memory, an SD card, etc.) by having a reading unit (not shown) read the data.
Furthermore, if the acquisition of dynamic image I is the trigger for starting the dynamic analysis process, this acquisition process is not necessary.

(Placement Processing)
After acquiring the dynamic image I, the control unit 41 executes a placement process (step S2).
In this placement process, the control unit 41 places a plurality of evaluation points P at a plurality of locations in the lung field region R _L captured in the dynamic image I, as shown in FIG.
In the placement process according to this embodiment, the control unit 41 places an evaluation point P in a lung field region _RL that appears in a reference frame F out of a plurality of frames F that constitute a dynamic image I.
In the placement process according to this embodiment, the control unit 41 sets the reference frame F to, for example, a frame showing the lung field region _RL at the maximum inspiration position (most expanded state). This reduces overlapping of blood vessels in the depth direction, thereby improving the tracking accuracy of the evaluation point P.
In the placement process according to this embodiment, the control unit 41 places evaluation points P at at least 10 locations in the left lung region and at least 10 locations in the right lung region of the lung field region _RL .

Furthermore, in the placement process according to this embodiment, the control unit 41 places the evaluation points P so that they are distributed in a matrix.
At this time, the control unit 41 arranges each evaluation point P so that the interval between two adjacent evaluation points P is greater than the size of a pixel (for example, about 0.4 mm).
Specifically, when the target region in which the evaluation points P are to be placed is the lung field region _RL , the interval between the evaluation points P is set to, for example, about 10 mm.
Furthermore, when the target region in which the evaluation points P are to be placed is the cardiac region, the interval between the evaluation points P is set to, for example, about 5 mm.
Furthermore, when the target region in which the evaluation points P are to be placed is the throat region, the interval between the evaluation points P is set to, for example, about 2 mm.

Furthermore, in the placement process according to this embodiment, the control unit 41 divides the multiple evaluation points P arranged in a matrix into n (here, 3) rows vertically and m (here, 3) columns horizontally, as shown in FIG. 6, and each divided group of n x m (here, 9) evaluation points P constitutes one group G.
The control unit 41 may be configured to group less than nine evaluation points P into one group G in the peripheral portion of the lung field region _RL .

In this arrangement process, the control unit 41 may arrange the evaluation points P in a staggered manner or randomly.
In addition, in this placement process, the control unit 41 may be configured to place the evaluation points P outside the lung field region _RL as well.
Furthermore, in this placement process, the control unit 41 may be configured to determine the placement location of the evaluation point P described above in accordance with operations performed on the operation unit 45 (user preferences) rather than automatically determining the placement location of the evaluation point P in accordance with the above.
In addition, after the control unit 41 automatically determines the placement locations of the evaluation points P, the placement of any evaluation points P may be adjusted in response to an operation performed on the operation unit 45 .

Furthermore, when arranging the evaluation points P, the control unit 41 may vary the density (arrangement interval) of the evaluation points P arranged in the lung field region R _L for each part. For example, for a dynamic image I of the lung field region R _L obtained by dynamic imaging in a standing position, the lung field region R _L is divided into an upper lung field region and a lower lung field region (or an upper lung field region, a middle lung field region, and a lower lung field region), and more evaluation points P are arranged in the lower lung field region than in other regions. This is because the lower lobes of the lungs move more when breathing in a standing position.
Furthermore, when placing the evaluation points P, the control unit 41 may be configured to determine the placement density of the evaluation points P in accordance with operations performed on the operation unit 45, rather than automatically determining the placement density of the evaluation points P as described above.
The control unit 41 performs the above-described arrangement process, thereby serving as an arrangement means in the systems 100 and 100A.

(Measurement processing)
After placing the evaluation points P in the lung field region R _L , the control unit 41 executes a measurement process (step S3).
In this measurement process, the control unit 41 first analyzes the movement of each evaluation point P.
Specifically, the control unit 41 uses image processing (e.g., optical flow (dense optical flow)) on the dynamic image I to estimate where a small area of a specific density around the evaluation point P will move to in the next frame F, thereby determining the amount and direction of movement of each evaluation point P in each frame F.
This makes it possible for each evaluation point P to move on the dynamic image I in accordance with the movement of the lung field region _RL .
For example, if the evaluation point P (hereinafter referred to as the reference evaluation point P _C ) located at the center of each group G is used as the reference (fixed and observed), the other surrounding evaluation points P will move radially away from the reference evaluation point P _C when the lung field region R _L expands, and will move closer to the reference evaluation point P _C when the lung field region R _L contracts, as shown in Figure 7 .

After analyzing the movement of the evaluation points P, the control unit 41 measures the change over time of the distances between the multiple evaluation points P (hereinafter, distance information) (the change accompanying the playback of the dynamic image I).
In this measurement process, the control unit 41 measures the change over time in distance information for each group G of evaluation points P that have been divided in advance.
In the calculation process according to this embodiment, the control unit 41 calculates, for each of a plurality of groups G in a single frame F, the average value of each distance from the reference evaluation point P _C in the single group G to the other evaluation points P arranged around the single group G, and regards the calculated average value as the distance information for the single group G in a single frame F.
Furthermore, the control unit 41 calculates the distance information in each group G for each of the multiple frames F. The distance information in one group G obtained from each frame F arranged in chronological order represents the change in the distance information in the same group G over time.

In addition, in this measurement process, the control unit 41 may calculate the area of a polygon whose vertices are the reference evaluation point P _C of group G and other evaluation points P arranged around it, and use that area as distance information.
In addition, in this measurement process, the control unit 41 may be configured to take the average value of some of the distances between all other evaluation points P in the group G and the reference evaluation point P _C as the distance information.
Further, the subsequent calculations may be performed using any one of the distances between all the other evaluation points P in the group G and the reference evaluation point P _C (without calculating the distance information).
The control unit 41 performs the measurement process described above, thereby serving as a measurement means in the systems 100 and 100A.

(Calculation process)
After measuring the change over time in the distance information, the control unit 41 executes a calculation process (step S4).
In this calculation process, the control unit 41 calculates information indicating the ventilation function of the lungs based on the change over time in the measured distance information.
In the calculation process according to this embodiment, the control unit 41 calculates a numerical value of at least one of the lung expansion volume and the lung ventilation volume as information indicating the ventilation function.
Specifically, the difference between the distance information in a frame F depicting the lung field region R _L in a first state and the distance information in a frame F depicting the lung field region R _L in a second state different from the first state is calculated as the amount of change in the distance information.
In the calculation process according to the present embodiment, the control unit 41 sets the "first state" to, for example, the maximum expiratory level and the "second state" to the maximum inspiratory level. In this way, the maximum value of the amount of change can be calculated.
Moreover, the control unit 41 calculates the amount of change for each group G.

Furthermore, after calculating the amount of change, the control unit 41 links each calculated amount of change to the reference evaluation point P _C as the amount of change at the location where the reference evaluation point P _C is located.

Furthermore, in the calculation process according to this embodiment, the control unit 41 calculates the amount of change in a small region R _S (pixels) in which no evaluation point P is located, based on each calculated amount of change.
Specifically, for example, as shown in FIG. 8, the change amounts are calculated by linear interpolation based on the distances (number of pixels) from two reference evaluation points P _C associated with each other.

After calculating the amount of change, the control unit 41 calculates a numerical value of at least one of the lung expansion volume and the lung ventilation volume based on the calculated amount of change.
When calculating the amount of lung expansion, the control unit 41 sums up all the calculated amounts of change and determines the sum as the amount of lung expansion.
On the other hand, when calculating the ventilation volume of the lungs, the control unit 41 sums up the amounts of change calculated by multiplying each amount by a predetermined coefficient, and determines the sum as the ventilation volume.
The coefficients are determined in advance, for example, based on the results of clinical experiments.

In this calculation process, the control unit 41 may calculate the ventilation volume or ventilation rate of the left lung and the ventilation volume or ventilation rate of the right lung separately.
In addition, when multiplying the amount of change by a coefficient in this calculation process, the control unit 41 may vary (weight) the coefficient to be multiplied depending on the part in the lung. For example, for a dynamic image I of the lung field region R _L obtained by dynamic imaging in a standing position, the coefficient to be multiplied by the amount of change obtained from the upper lung field region is relatively small, and the coefficient to be multiplied by the amount of change obtained from the lower lung field region is relatively large. This is because the amount of ventilation in the upper lobes is small when breathing in a standing position.
In addition, in this calculation process, the control unit 41 may calculate the rate of change of the distance from the amount of change. In this way, the ease with which the lungs expand and contract (pulmonary compliance) can be obtained as information indicating the ventilation function.
The control unit 41 performs the calculation process described above, thereby serving as a calculation means in the systems 100 and 100A.

(Output processing)
After calculating the value indicating the ventilation function, the control unit 41 executes an output process (step S5).
In this output process, the control unit 41 outputs information indicating the calculated ventilation function of the lungs.
That is, in this output process, the control unit 41 outputs a numerical value of at least one of the lung expansion volume and the lung ventilation volume based on the change over time of the measured distance information.

In the output process according to this embodiment, the control unit 41 causes the display unit 44 to display the numerical value of at least one of the expansion volume and the ventilation volume in the form of an image using a color map M, as shown in FIG. 9, for example.
Specifically, the control unit 41 makes the display color (e.g., blue (a color that evokes air)) of areas with relatively small expansion or ventilation volumes relatively lighter, and makes the display color of areas with relatively large expansion or ventilation volumes relatively darker.
At this time, the control unit 41 may compare the expansion volume or ventilation volume with a predetermined threshold value, and not display the color indicating the expansion volume or ventilation volume for areas showing a ventilation volume below the threshold value.
In addition, when an evaluation point P is placed in the area outside the lung field area _RL and the amount of change in the outer area is also calculated, the control unit 41 may be configured to mask the outer area and not display a color indicating the expansion or ventilation volume in that area (only displaying the lung field area _RL where the expansion or ventilation volume is effective).

In addition, in this output process, the control unit 41 may be configured to superimpose the evaluation score P on the dynamic image I.
In this case, the control unit 41 may treat one group G (group of evaluation points P) as one rough block (for example, a block formed by connecting multiple other evaluation points P surrounding a reference evaluation point _PC with lines), change the shape of the block G in accordance with the movement of the lung field region _RL , and fill the inner area (surrounded by the lines connecting the evaluation points P) with a color corresponding to the amount of change associated with the reference evaluation point _PC .
In addition, in this output process, the control unit 41 may display each calculated change amount as a vector (so that the extension direction can be seen).
In addition, in this output process, the control unit 41 may display the numerical values of at least one of the expansion volume and the ventilation volume in a graph (for example, a three-dimensional bar graph with the lung field region _RL on the XY plane and the expansion volume and the ventilation volume on the Z axis).
The control unit 41 performs the output process described above, thereby serving as an output unit in the systems 100 and 100A.

(Dynamic analysis processing, etc.)
In the dynamic analysis process, the control unit 41 may be configured to execute an attenuation process before executing a placement process.
In this case, the control unit 41 attenuates the signal value components of the bones that appear in the lung field region R _L .
Then, in the placement process, the control unit 41 places an evaluation point P on the dynamic image I in which the signal value components of the bones are attenuated.
In this manner, the control unit 41 serves as an attenuation means in the system 100, 100A, and the tracking accuracy of the evaluation point P can be improved.

In addition, in the dynamic analysis process, the control unit 41 may be configured to execute the manifestation process before executing the placement process.
In this case, the control unit 41 visualizes the blood vessels that appear in the lung field region R _L .
Methods for making the blood vessels more visible include, for example, a method of emphasizing the contours of the blood vessels by edge enhancement processing, a method of reducing the effects of noise by smoothing processing, and a method of dividing an image into blood vessels and other parts by binarization processing.
Then, in the placement process, the control unit 41 places an evaluation point P on the dynamic image I in which the blood vessels are visualized (for example, on the blood vessels).
In this way, the control unit 41 serves as a revealing means in the system 100, 100A, and the tracking accuracy of the evaluation point P can be improved.

<3. Actions and Effects>
The dynamic analysis device 4 according to the present embodiment described above includes a control unit 41 (measurement means, output means) which is arranged at multiple locations in the lung field region _RL of the subject depicted in a dynamic image I consisting of multiple frames F, measures the change over time in the distance between multiple evaluation points P which move following the movement of the _lung field region RL, and outputs information indicating the ventilation function of the subject's lungs based on the change over time in the distance between the measured evaluation points P.

For this reason, when the dynamic analysis device 4 is used to analyze a dynamic image I obtained by dynamic imaging of the chest of a subject S in a standing position, for example, the movement of the evaluation point P is captured (not a change in signal value), so no artifacts due to movement, deformation, etc. of parts other than the lungs are generated in the upper lung field region. As a result, the information indicating the ventilation function output by the dynamic analysis device 4 accurately represents the actual ventilation function of the lungs, as shown in Figure 9 (the ventilation function of the upper lung field region (area surrounded by a circle) appears to be lower than that of the middle and lower lung field regions).
Furthermore, in the analysis using this dynamic analysis device 4, it is not necessary to detect with high accuracy the blood vessels shown in the dynamic image I. Therefore, when this dynamic analysis device 4 is used, the time from the end of dynamic imaging to the start of diagnosis can be shortened compared to the conventional method.
Furthermore, this dynamic analysis device 4 can analyze the dynamics even in peripheral areas where there are no blood vessels or where the blood vessels are so thin that they cannot be detected, by locating the evaluation point P. Therefore, when this dynamic analysis device 4 is used, information indicating the ventilation function of the entire lungs can be obtained.

Therefore, with the dynamic analysis device 4 according to this embodiment, when analyzing the dynamic image I obtained by dynamic imaging of the lungs of the subject S, information indicating the ventilation function of the entire lungs can be obtained easily and in a relatively short time without being affected by the movement, deformation, etc. of parts other than the lungs.

＜4. Other＞
It goes without saying that the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention.

For example, in the above explanation, a hard disk or a non-volatile semiconductor memory is used as a computer-readable medium for the program according to the present invention, but the present invention is not limited to this example. Portable recording media such as CD-ROMs can be used as other computer-readable media. Furthermore, carrier waves can also be used as a medium for providing data for the program according to the present invention via a communication line.

100, 100A Radiography system 1 Imaging device 2 Console 2A Console (kinetic analysis device)
3 Generator 31 Generator 32 Irradiation instruction switch 33 Radiation source 4 Dynamic analysis device 41 Control unit 42 Memory unit 43 Communication unit 44 Display unit 45 Operation unit A Artifact F Frame G Group I Dynamic image M Color map N Communication network P Evaluation point P _C Reference evaluation point R _L Lung field area R _S Small area S Subject X Radiation

Claims (15)

a measuring means for specifying the positions of a plurality of evaluation points arranged in a lung field area captured in a frame in frames other than the frame by estimating where a small area of a specific density around the evaluation point will move in the next frame, calculating the distance between the plurality of evaluation points for each frame , and measuring the change over time in the distance between the plurality of evaluation points based on the distance between the plurality of evaluation points;
and an output means for outputting information indicating the ventilatory function of the subject's lungs based on the change over time in the distance between the evaluation points measured by the measurement means. a measuring means for specifying the positions of a plurality of evaluation points arranged in a lung field area captured in a frame in frames other than the frame by estimating where a small area of a specific density around the evaluation point will move in the next frame, calculating the distance between the plurality of evaluation points for each frame , and measuring the change over time in the distance between the plurality of evaluation points based on the distance between the plurality of evaluation points;
and an output means for outputting information indicating a ventilatory function of the lungs of the subject based on a change over time in the distance between the evaluation points measured by the measurement means ,
The measurement means calculates the area of a polygon whose vertices are three or more of the evaluation points arranged around a reference evaluation point for each group of evaluation points that have been divided in advance, and the area of the polygon is used as distance information for the group . 3. The dynamic analysis apparatus according to claim 1, wherein the output means outputs a numerical value of at least one of a pulmonary ventilation volume and a pulmonary expansion volume as the information indicating the ventilation function. the measuring means measures a change over time in distances between a plurality of the evaluation points for each group of the evaluation points that has been divided in advance;
4. The dynamic analysis device according to claim 3 , wherein the output means outputs a value of at least one of the expansion volume and the ventilation volume based on a change over time of the plurality of distances measured by the measurement means. 5. The dynamic analysis device according to claim 3 , wherein the output means outputs a numerical value of at least one of the expansion volume and the ventilation volume in the form of an image using a color map. A calculation means for calculating a value of at least one of the expansion volume and the ventilation volume based on a change over time of the distance between the evaluation points measured by the measurement means,
6. The dynamic analysis device according to claim 3 , wherein the output means outputs a numerical value of at least one of the expansion volume and the ventilation volume calculated by the calculation means. The calculation means is
calculating, as a change in distance, a difference between a distance between the evaluation point serving as a reference in a frame showing the lung field region in a first state and the other evaluation points arranged around it, and a distance between the evaluation point serving as a reference in a frame showing the lung field region in a second state different from the first state and the other evaluation points arranged around it;
The dynamic analysis device according to claim 6 , further comprising a step of calculating a value of at least one of the expansion volume and the ventilation volume based on the calculated change amount. The dynamic analysis apparatus according to claim 7 , wherein the first state is a maximum expiratory level. The dynamic analysis apparatus according to claim 1 , further comprising: a placement unit that places a plurality of the evaluation points in the lung field region. Further, the imaging apparatus includes an attenuation means for attenuating a signal value component of a bone appearing in the lung field region,
The dynamic analysis device according to claim 9 , wherein the positioning means positions the evaluation points on a dynamic image in which the signal value components of the bones have been attenuated by the attenuation means. A visualization means for visualizing blood vessels in the lung field region,
11. The dynamic analysis device according to claim 9 , wherein the positioning means positions the evaluation points on a dynamic image in which the blood vessels are visualized by the visualization means. The dynamic analysis device according to claim 9 , wherein the arrangement means automatically determines the arrangement positions of the evaluation points. Further comprising an operation unit operable by a user,
12. The dynamic analysis device according to claim 9 , wherein the arrangement means determines the arrangement positions of the evaluation points in response to an operation performed on the operation unit. On the computer,
a measurement process for determining the positions of evaluation points arranged in a dynamic image consisting of a plurality of frames obtained by dynamic imaging of the lungs of a subject, the evaluation points being arranged in image data, in a frame other than the one frame , by estimating where a small area of a specific density around the evaluation points will move to in the next frame, calculating the distance between the plurality of evaluation points for each frame, and measuring the change over time in the distance between the plurality of evaluation points based on the distance between the plurality of evaluation points;
and an output process for outputting information indicating the ventilatory function of the subject's lungs based on the change over time in the distance between the evaluation points measured in the measurement process. On the computer,
a measurement process for determining the positions of evaluation points arranged in a dynamic image consisting of a plurality of frames obtained by dynamic imaging of the lungs of a subject, the evaluation points being arranged in image data, in a frame other than the one frame , by estimating where a small area of a specific density around the evaluation points will move to in the next frame, calculating the distance between the plurality of evaluation points for each frame, and measuring the change over time in the distance between the plurality of evaluation points based on the distance between the plurality of evaluation points;
an output process for outputting information indicating a ventilatory function of the lungs of the subject based on a change over time in the distance between the evaluation points measured in the measurement process ;
The measurement process is a program that calculates the area of a polygon whose vertices are three or more evaluation points arranged around a reference evaluation point for each group of evaluation points that have been divided in advance, and uses the area of the polygon as distance information for the group .

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