Dynamic analysis device, radiography system and program

Abstract

To output the same dynamic analysis result when a dynamic state indicated by an acquired dynamic image is the same even if an imaging condition differs in each imaging.SOLUTION: A dynamic analysis device 2 includes: analysis result generation means 21 for generating a dynamic analysis result A (a dynamic image, a static image, and a correlation value) by executing dynamic analysis for a dynamic image I acquired by executing dynamic imaging for a subject S by a radiation X; correction means 21 for correcting variations attributed to a difference in imaging conditions (body thickness and radiation dose) for each imaging in the dynamic analysis result A generated by the analysis result generation means 21 on the basis of a correction value calculated on the basis of a conversion formula; and output means 21 for outputting a dynamic analysis result AC after the correction by the correction means 21.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a dynamic analysis device, a radiography system, and a program. [Background technology]

[0002] Conventionally, one of multiple frame images constituting a dynamic image of the chest is set as a reference frame, and the difference between the pixel values ​​of pixels in the lung field area extracted from the reference frame image and the pixel values ​​of corresponding pixels in the other frame images (the amount of change in density from the reference frame image) is calculated as the blood flow feature of each pixel (see, for example, Patent Document 1). It has also been conventional to recognize a region of interest from image data, extract features from the region of interest, and perform gradation conversion on the image data based on the extracted features (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-151232 A [Patent Document 2] JP 2003-250789 A Summary of the Invention [Problem to be solved by the invention]

[0004] The blood flow feature amount calculated by the conventional technology described in Patent Document 1 was a relative value that fluctuated depending on the imaging conditions (e.g., the thickness of the subject, the dose of radiation that penetrated the subject, etc.). For this reason, when subjects with similar blood flow conditions in the lung fields were imaged, the display based on the blood flow feature amount of one subject may appear to have sufficient blood flow, while the display based on the blood flow feature amount of the other subject may appear to have weak blood flow. Such differences in appearance of the display may cause misdiagnosis. Furthermore, the conventional technology for performing gradation processing on moving images as described in Patent Document 2 corrects the signal values ​​of the image data themselves with the aim of making the moving images easier to view, and cannot be applied to dynamic analysis results (such as signal value differences).

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to output similar dynamic analysis results even if there are differences in the shooting conditions for each shooting, if the dynamics shown in the obtained dynamic images are similar. [Means for solving the problem]

[0006] In order to solve the above problems, a dynamic analysis device according to the present invention comprises: an analysis result generating means for generating a dynamic analysis result by performing dynamic analysis on a dynamic image obtained by performing dynamic imaging on a subject using radiation; a correction means for correcting the variation of the dynamic analysis result generated by the analysis result generating means, the variation being caused by the difference in the imaging conditions for each imaging; and an output means for outputting the dynamic analysis result corrected by the correction means, The correction means corrects the kinetic analysis result based on a conversion formula for correcting the kinetic analysis result, The conversion formula is a threshold value obtained by quantifying a plurality of spatial direction feature amounts obtained by different dynamic imaging and a state of a part corresponding to a pixel showing the spatial direction feature amount. and This is an approximation of the relationship between the spatial direction feature and the threshold based on the law of nature, The correction means substitutes the spatial direction feature amount into the conversion formula to calculate a threshold value, calculates a multiplier required to make the calculated threshold value a target value as a correction value, and multiplies the dynamic analysis result by the correction value to perform correction. do.

[0007] Further, the radiation imaging system according to the present invention comprises: an image generating means for generating a dynamic image by performing dynamic radiography on a subject; an analysis result generating means for generating a dynamic analysis result by performing a dynamic analysis on the dynamic image generated by the image generating means; a correction means for correcting the variation of the dynamic analysis result generated by the analysis result generating means, the variation being caused by the difference in the imaging conditions for each imaging; and an output means for outputting the dynamic analysis result corrected by the correction means, The correction means corrects the kinetic analysis result based on a conversion formula for correcting the kinetic analysis result, The conversion formula is a threshold value obtained by quantifying a plurality of spatial direction feature amounts obtained by different dynamic imaging and a state of a part corresponding to a pixel showing the spatial direction feature amount. and This is an approximation of the relationship between the spatial direction feature and the threshold based on the law of nature, The correction means substitutes the spatial direction feature amount into the conversion formula to calculate a threshold value, calculates a multiplier required to make the calculated threshold value a target value as a correction value, and multiplies the dynamic analysis result by the correction value to perform correction. do.

[0008] In addition, the program according to the present invention is On the computer, an analysis result generation process for generating a dynamic analysis result by performing a dynamic analysis on a dynamic image obtained by performing a dynamic image capturing process on a subject using radiation; a correction process for correcting variations in the dynamic analysis results generated by the analysis result generation process, the variations being caused by differences in the imaging conditions for each imaging; and an output process for outputting the dynamic analysis result corrected by the correction process. the correction process corrects the kinetic analysis result based on a conversion formula for correcting the kinetic analysis result; The conversion formula is a threshold value obtained by quantifying a plurality of spatial direction feature amounts obtained by different dynamic imaging and a state of a part corresponding to a pixel showing the spatial direction feature amount. and This is an approximation of the relationship between the spatial direction feature and the threshold based on the law of nature, The correction process includes substituting the spatial direction feature amount into the conversion formula to calculate a threshold value, calculating a multiplier required to make the calculated threshold value a target value as a correction value, and multiplying the dynamic analysis result by the correction value to perform correction. do. Effect of the Invention

[0009] According to the present invention, even if the shooting conditions differ for each shooting, if the dynamics shown in the obtained dynamic images are similar, similar dynamic analysis results can be output. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a radiation imaging system according to an embodiment of the present invention; [Diagram 2] 2 is a block diagram showing a dynamic analysis device provided in the radiography system of FIG. 1. [Diagram 3] 3 is a flowchart showing the flow of a dynamic analysis process executed by the dynamic analysis device of FIG. 2. [Figure 4] 3 is an image diagram showing an example of processing executed by the dynamic analysis device of FIG. 2. [Diagram 5] 3 is a conceptual diagram showing an example of a technique used in the processing executed by the dynamic analysis device of FIG. 2. [Figure 6] FIG. 6 is an image diagram showing an example of an image output by a dynamic analysis device to which the technique of FIG. 5 is applied. [Figure 7] 3 is a conceptual diagram showing an example of processing executed by the dynamic analysis device of FIG. 2. [Figure 8] 3 is a conceptual diagram showing an example of processing executed by the dynamic analysis device of FIG. 2. [Figure 9] 3 is a conceptual diagram showing an example of processing executed by the dynamic analysis device of FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited to the following embodiments and illustrated examples.

[0012] <1. Overview of the Radiography System> First, an overview of a radiation imaging system according to this embodiment (hereinafter, referred to as a system 100) will be described. FIG. 1 is a block diagram illustrating a system 100 .

[0013] As shown in FIG. 1, the system 100 includes a radiography device (hereinafter, referred to as the radiography device 1) and a dynamic analysis device 2. The system 100 according to this embodiment further includes a radiation generating device (hereinafter, referred to as a generating device 3) and a console 4. The devices 1 to 4 are capable of communicating with each other via, for example, a communication network N (such as a local area network (LAN), a wide area network (WAN), or the Internet).

[0014] In addition, the system 100 may be capable of communicating with a hospital information system (HIS), a radiology information system (RIS), a picture archiving and communication system (PACS), etc., which are not shown.

[0015] [1-1. Radiation Generator] The generator 3 generates the X-ray. The generating device 3 includes a generator 31 , an irradiation instruction switch 32 , and a radiation source 33 . The irradiation instruction switch 32 may be connected to the generator 31 via an operation console (not shown).

[0016] [1-1-1. Generator] When the irradiation instruction switch 32 is operated, the generator 31 applies a voltage to the radiation source 33 (tube) according to preset imaging conditions (conditions related to the subject S (imaged part, imaging direction, body size, body thickness, etc.), conditions related to the irradiation of radiation X (imaging mode (still image shooting, dynamic image shooting, etc.), tube voltage, tube current, irradiation time, current-time product (mAs value), etc.) and passes a current according to the imaging conditions to the radiation source 33.

[0017] [1-1-2.Radiation source] When a voltage is applied from the generator 31 and a current is passed through the radiation source 33, the radiation source 33 generates radiation X (e.g., X-rays) with a dose corresponding to the applied voltage and the passed current. In addition, the radiation source 33 is capable of moving in the X-axis direction, the Y-axis direction perpendicular to the X-axis, and the Z-axis direction perpendicular to the X-axis and Y-axis, and is also capable of rotating about a rotation axis parallel to the Y-axis and Z-axis to change the orientation of the radiation X irradiation port.

[0018] [1-1-3. Operation of the radiation generating device] The generator 3 thus configured is adapted to generate radiation X in a manner appropriate 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.

[0019] [1-1-4. Radiation Generators and Others] The generating device 3 may be installed in the radiography room, or may be configured together with the console 4 and the like as a movable device called a mobile cart.

[0020] [1-2.Radiation imaging device] Although not shown in the figure, the imaging device 1 is equipped with a sensor substrate on which pixels are arranged in a two-dimensional form (in a matrix), the pixels having radiation detection elements that generate an electric charge according to the dose when exposed to radiation X, and switching elements that store and release electric charge, a scanning circuit that switches each switching element on / off, a readout circuit that reads out the amount of electric charge released from each pixel as a signal value, a control unit that generates a radiographic image from the multiple signal values ​​read out by the readout circuit, and a communication unit that transmits data on the generated radiographic image and various signals to the outside and receives various information and signals.

[0021] The imaging device 1 accumulates and releases electric charges and reads out signal values ​​in synchronization with the timing at which radiation X is irradiated from the generating device 3, thereby generating a radiological image according to the dose of the irradiated radiation X. 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 a dynamic image is to be generated, 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.

[0022] The imaging device 1 may be integrated with the generating device 3 (for example, a CT (Computed Tomography) device, etc.). The photographing device 1 may be configured to store and transfer the generated dynamic image in the form of image data, or to display it in real time on a display device connected to the photographing device 1. An example of real-time display is fluoroscopy.

[0023] [1-3. Console] The console 4 is composed of a PC, a mobile terminal, a dedicated device, etc. Moreover, the console 4 sets the above-mentioned imaging conditions in at least one of the imaging device 1 and the generating device 3. Furthermore, the console 4 sets the imaging conditions based on imaging order information acquired from another system (such as an HIS or RIS) or on an operation performed by a user (such as a technician). The console 4 is also capable of acquiring image data of a radiation image generated by the imaging device 1, storing the image data in itself, or transmitting the image data to other devices (the dynamic analysis device 2, PACS, etc.).

[0024] [1-4.Dynamic analysis device] The dynamic analysis device 2 performs dynamic analysis on dynamic images acquired from another device, thereby generating dynamic analysis results. The dynamic analysis device 2 is composed of a PC, a dedicated device, and the like. The dynamic analysis device 2 will be described in detail later.

[0025] [1-5. Outline of operation of the radiography system] The system 100 configured in this manner operates as follows. First, the generator 3 irradiates radiation X to the subject S (the area to be diagnosed of the examinee) located between the radiation source 33 of the generator 3 and the imaging device 1, which are arranged opposite each other with a gap between them. The imaging device 1 then generates a radiation image (still image, dynamic image) showing the area to be diagnosed, and transmits the image data to at least one of the dynamic analysis device 2 and the console 4. That is, the imaging device 1 serves as an image generating means for generating a dynamic image by performing dynamic imaging of the subject S using radiation X. When the behavior analysis device 2 receives the image data, it executes a behavior analysis process (described in detail later) and outputs the behavior analysis result.

[0026] [1-6. Radiography systems and others] So far, the system 100 has been described as including the dynamic analysis device 2 in addition to the console 4, but the console 4 may also function as the dynamic analysis device. Specifically, the radiation imaging system may be configured with the imaging device 1, the generator 3, and a console that also functions as a dynamic analysis device.

[0027] <2. Details of the dynamic analysis device> Next, the dynamic analysis device 2 included in the above-mentioned system 100 will be described in detail. FIG. 2 is a block diagram showing the behavioral analysis device 2, FIG. 3 is a flowchart showing the flow of the behavioral analysis process executed by the behavioral analysis device 2, and FIGS. 4 to 7 are image diagrams and conceptual diagrams showing an example of the process executed by the behavioral analysis device 2.

[0028] [2-1. Configuration of dynamic analysis device] As shown in FIG. 2, the dynamic analysis device 2 includes a control unit 21, a storage unit 22, a communication unit 23, and It is equipped with: The dynamic analysis device 2 according to this embodiment further includes a display unit 24 and an operation unit 25. The units 21 to 25 are electrically connected to each other via a bus or the like.

[0029] The control unit 21 is composed of a CPU (Central Processing Unit), a RAM (Random Access Memory), and the like. The CPU of the control unit 21 reads out various programs stored in the memory unit 22 and expands them in the RAM, executes various processes according to the expanded programs, and provides centralized control of the operation of each part of the dynamic analysis device 2.

[0030] The storage unit 22 is composed of a non-volatile memory, a hard disk, or the like. Moreover, the storage unit 22 stores various programs (including a program for dynamic analysis processing, which will be described later) executed by the control unit 21, parameters required for executing the programs, and the like. The storage unit 22 according to this embodiment stores a predetermined conversion formula. The conversion formula will be described in detail later. Moreover, the storage unit 22 according to the present embodiment stores the correspondence relationship (color map) between the signal value (difference value) and the RGB value. In addition, the memory unit 22 in this embodiment is capable of storing image data of radiation images acquired from other devices (such as the imaging device 1) and image data of various images generated by the control unit 21 based on dynamic images.

[0031] The communication unit 23 is composed of a communication module and the like. The communication unit 23 is configured to transmit and receive various signals and data to and from other devices (the photographing device 1, the console 4, etc.) connected by wire or wirelessly via a communication network N (LAN (Local Area Network), WAN (Wide Area Network), the Internet, etc.).

[0032] The display unit 24 displays various screens used for diagnosis by the user. The display unit 24 is composed of, for example, an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube), or the like. The display unit 24 displays a radiographic image corresponding to the image signal received from the control unit 21, a dynamic analysis result, and the like.

[0033] The operation unit 25 is configured so as to be operable by the user. The operation unit 25 includes 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 24, and the like. The operation unit 25 outputs to the control unit 21 a control signal corresponding to an operation performed by the user.

[0034] In addition, the dynamic analysis device 2 may not be equipped with a display unit 24 and an operation unit 25, and may be configured to receive control signals from an input device provided separately from the dynamic analysis device 2, for example via a communication unit 23, or to output image signals to a display device (monitor) provided separately from the dynamic analysis device 2. In addition, if the other device (console 4, etc.) has a display unit and an operation unit, it may be configured to receive control signals from the operation unit of the other device and output image signals to the display unit of the other device (the display unit and operation unit may be shared with the other device).

[0035] [2-2. Operation of the dynamic analysis device] The control unit 21 of the behavior analysis device 2 configured as above executes a behavior analysis process, for example, as shown in FIG. 3, when a predetermined condition is met. The specified conditions include, for example, the power of the dynamic analysis device 2 being turned on, image data of a dynamic image being acquired from another device, a specified control signal being received from another device, and a specified operation being performed on the operation unit 25.

[0036] 2-2-1. Acquiring dynamic images In this dynamic analysis process, the control unit 21 first executes an acquisition process (step S1). In this acquisition process, the control unit 21 acquires dynamic images from other devices (the imaging device 1, the console 4, the PACS, etc.). In the acquisition process according to this embodiment, the control unit 21 receives information from another device via the communication unit 23. It should be noted that when the dynamic analysis process is started in response to acquisition of image data of a dynamic image, this acquisition process is not necessary.

[0037] [2-2-2. Setting the processing area] In the dynamic analysis process according to this embodiment, the control unit 21 acquires a dynamic image and then executes an analysis region setting process (step S2). In this analysis region setting process, the control unit 21 sets an analysis region R in the dynamic image I. A Set. This "analysis area R A " is the processing area R set in the processing area setting process described later. P or the processing area R P and includes, for example, a lung field region, a heart region, etc. In this analysis region setting process, the control unit 21 sets the analysis region R A The area to be detected is recognized, and a contour is set so as to surround the recognized area.

[0038] In addition, in this analysis region setting process, the control unit 21 manually or automatically sets the analysis region R A Set. Analysis area R A The method of setting is not particularly limited, but the analytical region R A When automatically setting, the control unit 21 sets an analysis region R A A trained model that has been machine-learned to output the above information may be used.

[0039] Meanwhile, the shape of a lung field region can be expressed by the following formula (1) using a principal component analysis technique using lung field data D of a plurality of various shapes (coordinates) as shown in FIG. M+Ae1+Be2+Ce3+··(1) M: average shape coordinates, A, B, C...=constant, e i (i=1,2,3 ) = Principal component vector For this reason, the lung field area is analyzed as R A When automatically setting to , the trained model uses the dynamic image I of the lung field as input data, and the principal component vector e in the above formula (1) is i It is possible to use a machine learning (deep learning) system that outputs combinations of the above. By using such a trained model, when a dynamic chest image I is input, a lung field (analysis area R) with multiple contour points P on the contour line of the lung field region, as shown in Fig. 6, is generated. A ) dynamic image I can be output. In addition, when displaying the contour of the lung field based on the output, multiple contour points P are each spline-interpolated to obtain the analysis region R A It is possible to generate contour lines of the

[0040] In the analytical region setting process according to this embodiment, the control unit 21 also executes a block region setting process. In this block region setting process, the control unit 21 divides each frame constituting the dynamic image I into a plurality of block regions R each having a size of one pixel or more. B Divide into: In the block region setting process according to this embodiment, the control unit 21 sets the analysis region R A multiple block regions R B Divide into: In the block region setting process according to the present embodiment, the control unit 21 sets the analysis region R A For example, as shown in FIG. 4, a rectangular block region R of 10 mm×10 mm arranged in a matrix is B Or, a smoothing process of 10 mm × 10 mm size is performed for each pixel, and one pixel is divided into a block region R BSet as.

[0041] The control unit 21 according to the present embodiment serves as a block region setting means by executing the analysis region setting process described above.

[0042] [2-2-3. Generation of dynamic analysis results] After acquiring the dynamic image I or the analysis area R A After setting, the control unit 21 executes the analysis result generation process as shown in FIG. 3 (step S3). In this analysis result generating process, the control unit 21 generates a dynamic analysis result A by performing a dynamic analysis on the dynamic image I. In the analysis result generating process according to this embodiment, the control unit 21 generates, as the dynamic analysis result A, (a) a moving image consisting of a plurality of frames, (b) a still image, or (c) a correlation value.

[0043] (a. When generating video images as dynamic analysis results) In the analysis result generation process in which the dynamic analysis result A becomes a moving image, the control unit 21 generates the dynamic analysis result A as the difference between the signal value of a pixel in one frame that constitutes the dynamic image I and the signal value of a pixel corresponding to the pixel in another frame. Specifically, first, a reference frame setting process is executed. In this reference frame setting process, the control unit 21 sets one frame constituting the dynamic image I as an initial reference frame. In the reference frame setting process according to the present embodiment, the control unit 21 sets the block region R B Each time, a different frame is set as the reference frame.

[0044] Specifically, for example, as shown in FIG. 7, among a plurality of frames, the frame that exhibits the lowest signal value in a preset RPI (cardiac region) is set as the reference frame. Also, other block regions R B In one block region R BThe frame showing the highest signal value within a preset search range (for example, in the case of 15 fps, ±0.1333 seconds (two frames before and after)) from the reference frame in the block region R B The reference frame in is set as It is desirable for this "search range" to be equal to or less than half the time (seconds) required for one heartbeat. For example, if the number of frames obtained by imaging one heartbeat is 15, half the imaging time (search range) will include the reference frame ±7 frames. It should be noted that if the frame rate is changed, the number of frames within the search range also changes (for example, in the case of 30 fps, the number of frames within the search range is twice that in the case of 15 fps). After setting the reference frame, the control unit 21 sets the difference between the signal value of the pixel in the reference frame and the signal value of the pixel corresponding to the pixel in another frame as the dynamic analysis result A, and calculates the dynamic analysis result A in the block region R. B Generated every 10 seconds.

[0045] (b. When generating still images as dynamic analysis results) On the other hand, in the analysis result generating process in which the dynamic analysis result A becomes a still image, the control unit 21 first executes an evaluation value calculation process. In this evaluation value calculation process, the control unit 21 calculates an evaluation value of the change in signal value over time from the dynamic image I for each pixel. After calculating the evaluation values, the control unit 21 generates the maximum value, median value, minimum value, integrated value, or average value of the calculated evaluation values ​​as the dynamic analysis result A.

[0046] (c. When generating correlation values ​​as dynamic analysis results) In the analysis result generating process in which the dynamic analysis result A becomes the correlation value, the control unit 21 first executes a waveform acquiring process. In this waveform acquisition process, the control unit 21 acquires a reference signal waveform. Before, after, or in parallel with acquiring the reference signal waveform, the control unit 21 executes a waveform calculation process. In this waveform calculation process, the control unit 21 calculates a signal waveform from the dynamic image I acquired in the acquisition process. After acquiring the reference signal waveform and calculating the signal waveform, the control unit 21 generates, as a dynamic analysis result A, a correlation value indicating the correlation between the acquired reference signal waveform and the calculated signal waveform. The method described in JP 2012-239796 A can be used to obtain the reference signal waveform, calculate the signal waveform, and calculate the correlation value, for example.

[0047] The control unit 21 according to this embodiment performs the analysis result generating process described above, thereby serving as a reference frame setting means, a waveform acquiring means, a waveform calculating means, an evaluation value calculating means, and an analysis result generating means.

[0048] [2-2-4. Calculation of feature quantities] After generating the behavior analysis result A, the control unit 21 executes a feature amount calculation process as shown in FIG. 3 (step S4). In this feature amount calculation process, the control unit 21 calculates a spatial direction feature amount. Specifically, first, the control unit 21 executes a processing area setting process. In this processing region setting process, the control unit 21 sets a processing region R in the dynamic image I. P Set For example, when the subject S is the chest of a subject and the dynamic analysis result A is an analysis result regarding pulmonary blood flow, in this feature amount calculation process, the control unit 21 divides the lung field region, the pulmonary hilum region, the heart region, the aortic arch region, or the artery region into a processing region R P Set to.

[0049] (Processing when the dynamics analysis result is a video image) When the dynamic analysis result A is a video image (including a correlation value), the control unit 21 next executes a time direction feature amount calculation process. In this time direction feature calculation process, the control unit 21 calculates the maximum, median, minimum, integrated value or average value of the change in signal value over time from the dynamic analysis result A as the time direction feature value for each pixel. As described above, in the dynamic analysis process according to this embodiment, in order to execute the above-mentioned processing region setting process, in the time direction feature amount calculation process according to this embodiment, the control unit 21 sets the processing region R as shown in FIG. P The maximum value, median value, minimum value, integrated value or average value of the change in the signal value over time is calculated for each pixel as a time direction feature amount. In the time direction feature value calculation process according to this embodiment, the control unit 21 determines the minimum value of the change in signal value over time as the time direction feature value. In the time direction feature value calculation process according to the present embodiment, the control unit 21 generates a summary image I S (If the minimum value is used as the time direction feature, a MinIP image is created.)

[0050] Summary Image I S After creating the vector, the control unit 21 executes a spatial direction feature amount calculation process. In this spatial direction feature amount calculation process, the control unit 21 calculates the time direction feature amount of each pixel calculated in the above-mentioned time direction feature amount calculation process (summary image I S ), the maximum value, the median value, the minimum value, the integrated value, or the average value is calculated as the spatial direction feature amount. In the spatial direction feature value calculation process according to this embodiment, the control unit 21 determines the minimum value of the time direction feature values ​​as the spatial direction feature value.

[0051] (Processing when dynamic analysis results are still images) On the other hand, when the dynamic analysis result A is a still image, the control unit 21 skips the time direction feature amount calculation process and executes the space direction feature amount calculation process. From the dynamic analysis result A (still image) generated in the analysis result generation process, the maximum value, median value, minimum value, integrated value, or average value of the signal value of each pixel is calculated as a spatial direction feature amount. As described above, in the dynamic analysis process according to this embodiment, the processing region setting process is executed, so in the spatial direction feature amount calculation process according to this embodiment, the control unit 21 sets the processing region R PFrom the above, the maximum value, median value, minimum value, integrated value or average value of the change over time in the signal value of each pixel is calculated as the spatial direction feature amount. Moreover, in the spatial direction feature amount calculation process according to this embodiment, the control unit 21 determines the minimum value of the time direction feature amounts as the spatial direction feature amount.

[0052] In this processing region setting process, the control unit 21 sets the analysis region R A The processing area R P The setting may be set to . In addition, in this feature calculation process, the lung field area is treated as a processing area R P When the processing area R is set to 0, the control unit 21 sets the processing area R P In this way, the influence of the positional displacement of the structure on the lung field can be reduced. The control unit 21 according to the present embodiment performs the feature amount calculation process described above, thereby serving as a processing region setting means, a time direction feature amount calculation means, and a space direction feature amount calculation means.

[0053] [2-2-5. Calculation of correction value] After calculating the spatial direction feature amount, the control unit 21 executes a correction value calculation process as shown in FIG. 3 (step S5). In this correction value calculation process, the control unit 21 calculates a correction value based on the spatial direction feature amount calculated in the spatial direction feature amount calculation process and the conversion formula stored in the storage unit 22 . The conversion formula is used to correct the dynamic analysis result A, and is calculated based on at least two dynamic analysis results A: a dynamic analysis result A obtained by performing dynamic analysis on one dynamic image I, and a dynamic analysis result A obtained by performing dynamic analysis on another dynamic image I different from the one dynamic image I. Specifically, the conversion formula is a linear approximation of the distribution of a scatter plot plotting the relationship between multiple spatial direction feature amounts obtained by different dynamic imaging and threshold values ​​(gain values) that quantify the actual blood flow state when visually observing the area corresponding to the pixel showing the spatial direction feature amount, and is expressed in the form of the following formula (1). Threshold = constant a × spatial direction feature value – constant b (1)

[0054] Then, the control unit 21 substitutes the spatial direction feature amount calculated in the feature amount calculation process into the conversion formula to calculate a threshold value. Then, the control unit 21 sets a multiplier required to make the calculated threshold value the target value as a correction value (a value obtained by dividing the target value by the threshold value as the correction value).

[0055] In this correction value calculation process, the control unit 21 may newly calculate a conversion formula instead of using a conversion formula stored in advance. In addition, when executing this correction value calculation process, the control unit 21 may be configured to update the conversion formula stored in the memory unit 22 (to reflect the dynamic analysis result A of the newly acquired dynamic image I in the conversion formula). The control unit 21 according to the present embodiment serves as a correction value calculation means by executing the correction value calculation process described above.

[0056] [2-2-6. Correction of dynamic analysis results] After calculating the correction value, the control unit 21 executes a correction process (step S6). In this correction process, the control unit 21 corrects the dynamic analysis result A based on the correction value calculated in the correction value calculation process. More specifically, as shown in FIG. 9, the control unit 21 multiplies the dynamic analysis result A (the difference value, evaluation value, and correlation value of each pixel) by a correction value, and designates it as the corrected dynamic analysis result A. C Let us assume that. By the control unit 21 executing this correction process, the variation in the generated dynamic analysis result A caused by the difference in the imaging conditions for each imaging is corrected. The correction value used in this correction process is calculated based on the conversion formula stored in the storage unit 22 in the correction value calculation process, so it can also be said that the control unit 21 corrects the dynamic analysis result A based on the conversion formula. In the case where the dynamic analysis result A is a video image, in the correction process according to this embodiment, the control unit 21 corrects the summary image I generated in the time direction feature amount calculation process based on the correction value. S Also correct. The control unit 21 according to the present embodiment serves as a correction means by executing the correction process described above.

[0057] [2-2-7. Output of dynamic analysis results] After correcting the dynamic analysis result A, the control unit 21 executes an output process as shown in FIG. 3 (step S7). In this output process, the control unit 21 outputs the corrected dynamic analysis result A C Output. In the output process according to this embodiment, the control unit 21 outputs the corrected dynamic analysis result A C The corrected kinetic analysis result A is obtained by coloring each signal value according to the magnitude of the signal value. C is displayed in color on the display unit 24. Specifically, for example, each pixel is colored using a correspondence (color map) between difference values ​​and RGB values ​​stored in a storage unit.

[0058] In this output process, the control unit 21 outputs the dynamic analysis result A after correction based on a predetermined threshold value. C The signal values ​​of the above may be binarized, and the dynamic analysis result A may be displayed on the display unit 24 as a binarized image. In addition, in this output process, the control unit 21 may be configured to execute a threshold adjustment process. In this threshold adjustment process, the control unit 21 adjusts the threshold in response to an operation performed on the operation unit 25. The control unit 21 according to the present embodiment serves as a threshold adjustment unit and an output unit by executing the output process described above.

[0059] [2-2-8. Dynamic analysis processing etc.] In addition, in the above dynamic analysis process, the control unit 21 may be configured to apply a filter process to the signal values ​​of the dynamic image I to remove from the signal values ​​components of movements different from the movement of the subject of dynamic analysis (for example, breathing when blood flow is the subject of dynamic analysis). In addition, in the dynamic analysis process, the control unit 21 may skip the analysis region setting process and execute the analysis result generation process for the entire frame of the dynamic image. In addition, the control unit 21 sets the analysis region R A may be set as a plurality of small regions, and the dynamics analysis result A may be generated for each small region in the analysis result generation process.

[0060] <3.Effects> As described above, the dynamic analysis device 2 according to this embodiment performs dynamic analysis on a dynamic image I obtained by performing dynamic imaging of a subject S using radiation X, thereby generating a dynamic analysis result A, corrects the variation in the generated dynamic analysis result A caused by the difference in imaging conditions for each imaging, and generates the corrected dynamic analysis result A. C The control unit 21 (analysis result generating means, correction means, output means) outputs the above. Therefore, according to the dynamic analysis device 2 or system 100, even if the shooting conditions differ for each shooting, if the dynamics shown in the obtained dynamic image I are similar, the same dynamic analysis result A can be output.

[0061] <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.

[0062] For example, in the system 100 according to the above embodiment, the dynamic analysis device 2 is provided with the functions of an analysis result generating means, a correction means, and an output means, but at least any of these functions may be provided in a device other than the dynamic analysis device 2.

[0063] Also, for example, in the above description, 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. As other computer-readable media, a portable recording medium such as a CD-ROM can be applied. Furthermore, a carrier wave can be applied as a medium for providing data of the program according to the present invention via a communication line. [Explanation of symbols]

[0064] 100) Radiography System 1. Imaging device 2 Dynamic analysis device 21 Control section 22 Memory section 23 Communications Department 24 Display section 25 Control section 3. Radiation Generator 31 Generator 32 Irradiation switch 33 Radiation source 4 Console A Dynamic analysis results A C Corrected kinetic analysis results I Dynamic Images I S Summary Image N Communication Network P contour point R A analysis area R P Processing area R B Block Area S Subject X radiation

Claims

1. an analysis result generating means for generating a dynamic analysis result by performing dynamic analysis on a dynamic image obtained by performing dynamic imaging on a subject using radiation; a correction means for correcting the variation of the dynamic analysis result generated by the analysis result generating means, the variation being caused by the difference in the imaging conditions for each imaging; and an output means for outputting the dynamic analysis result corrected by the correction means, The correction means corrects the kinetic analysis result based on a conversion formula for correcting the kinetic analysis result, the conversion formula is a formula that approximates a relationship between a spatial direction feature amount and a threshold value based on a plurality of spatial direction feature amounts obtained by different dynamic imaging and threshold values ​​that digitize states of parts corresponding to pixels that indicate the spatial direction feature amounts, The correction means substitutes the spatial direction feature amount into the transformation formula to calculate a threshold value, calculates a multiplier required to make the calculated threshold value a target value as a correction value, and multiplies the dynamic analysis result by the correction value to perform correction.

2. The dynamic analysis apparatus according to claim 1 , further comprising a storage unit for storing the conversion formula.

3. The dynamic analysis result is a video image consisting of a plurality of frames, a time direction feature value calculation means for calculating a maximum value, a median value, a minimum value, an integrated value or an average value of a time-dependent change in a signal value for each pixel from the dynamic analysis result; a spatial direction feature amount calculation means for calculating a maximum value, a median value, a minimum value, an integrated value, or an average value as a spatial direction feature amount from the time direction feature amount of each pixel calculated by the time direction feature amount calculation means; a correction value calculation means for calculating a correction value based on the spatial direction feature calculated by the spatial direction feature calculation means and the transformation formula, 3. The kinetic analysis apparatus according to claim 1, wherein the correction means corrects the kinetic analysis result based on the correction value calculated by the correction value calculation means.

4. a processing region setting means for setting a processing region for the dynamic analysis result, The dynamic analysis device according to claim 3 , wherein the time direction feature calculation means calculates, for each pixel, a maximum value, a median value, a minimum value, an integrated value or an average value of a time-dependent change in signal value from the processing region set by the processing region setting means as the time direction feature.

5. The dynamic analysis result is a still image, a spatial direction feature amount calculation means for calculating a maximum value, a median value, a minimum value, an integrated value, or an average value of a signal value of each pixel as a spatial direction feature amount from the dynamic analysis result generated by the analysis result generation means; a correction value calculation means for calculating a correction value based on the spatial direction feature calculated by the spatial direction feature calculation means and the transformation formula, 3. The kinetic analysis apparatus according to claim 1, wherein the correction means corrects the kinetic analysis result based on the correction value calculated by the correction value calculation means.

6. a processing region setting means for setting a processing region for the dynamic analysis result, 6. The dynamic analysis device according to claim 5, wherein the spatial direction feature calculation means calculates, as the spatial direction feature, a maximum value, a median value, a minimum value, an integrated value or an average value of a time-dependent change in the signal value of each pixel from the processing area set by the processing area setting means.

7. the subject is a chest of a subject, The dynamic analysis result is an analysis result regarding pulmonary blood flow, 7. The dynamic analysis apparatus according to claim 4, wherein the processing region setting means sets a lung field region, a pulmonary hilum region, a heart region, an aortic arch region, or an artery region as the processing region.

8. The dynamic analysis device according to claim 7 , wherein, when the processing area setting means sets the lung field area as the processing area, the contour of the processing area is set closer to the center of the lung field than the contour of the actually recognized lung field.

9. The dynamic analysis device according to claim 1 or claim 2, wherein the analysis result generating means generates the difference between a signal value of a pixel in one frame constituting the dynamic image and a signal value of a pixel corresponding to the pixel in another frame as the dynamic analysis result.

10. a reference frame setting means for setting one frame constituting the dynamic image as a reference frame; 10. The dynamic analysis device according to claim 9, wherein the analysis result generating means generates, as the dynamic analysis result, a difference between a signal value of a pixel in the reference frame and a signal value of a pixel corresponding to the pixel in another frame.

11. a block region setting means for dividing each frame constituting the dynamic image into a plurality of block regions each having a size of one pixel or more; 11. The dynamic analysis apparatus according to claim 10, wherein the reference frame setting means sets a different frame as the reference frame for each block region set by the block region setting means.

12. A waveform acquisition means for acquiring a reference signal waveform; A waveform calculation means for calculating a signal waveform from the dynamic image, 3. The dynamic analysis device according to claim 1, wherein the analysis result generating means generates a value indicating the correlation between the reference signal waveform acquired by the waveform acquiring means and the signal waveform calculated by the waveform calculating means as the dynamic analysis result.

13. an evaluation value calculation means for calculating an evaluation value of a change in a signal value over time from the dynamic image; 3. The dynamic analysis device according to claim 1, wherein the analysis result generating means generates a maximum value, a median value, a minimum value, an integrated value, or an average value of the evaluation values ​​calculated by the evaluation value calculating means as the dynamic analysis result.

14. The dynamic analysis result is a moving image or a still image consisting of a plurality of frames, 3. The dynamic analysis device according to claim 1, wherein the output means displays the corrected dynamic analysis results in color on the display unit by coloring each signal value of the corrected dynamic analysis results according to the magnitude of the signal value.

15. The dynamic analysis result is a moving image or a still image consisting of a plurality of frames, The dynamic analysis device according to claim 1 or claim 2, wherein the output means binarizes each signal value of the corrected dynamic analysis result based on a predetermined threshold value, thereby displaying the corrected dynamic analysis result on the display unit as a binary image.

16. An operation unit that can be operated by a user; The dynamic analysis device according to claim 15 , further comprising: a threshold adjustment means for adjusting the threshold in response to an operation performed on the operation unit.

17. an image generating means for generating a dynamic image by performing dynamic radiography on a subject; an analysis result generating means for generating a dynamic analysis result by performing a dynamic analysis on the dynamic image generated by the image generating means; a correction means for correcting the variation of the dynamic analysis result generated by the analysis result generating means, the variation being caused by the difference in the imaging conditions for each imaging; and an output means for outputting the dynamic analysis result corrected by the correction means, The correction means corrects the kinetic analysis result based on a conversion formula for correcting the kinetic analysis result, the conversion formula is a formula that approximates a relationship between a spatial direction feature amount and a threshold value based on a plurality of spatial direction feature amounts obtained by different dynamic imaging and threshold values ​​that digitize states of parts corresponding to pixels that indicate the spatial direction feature amounts, the correction means substitutes the spatial direction feature amount into the transformation formula to calculate a threshold value, calculates a multiplier required to make the calculated threshold value a target value as a correction value, and multiplies the dynamic analysis result by the correction value to perform correction.

18. On the computer, an analysis result generation process for generating a dynamic analysis result by performing a dynamic analysis on a dynamic image obtained by performing a dynamic image capturing process on a subject using radiation; a correction process for correcting variations in the dynamic analysis results generated by the analysis result generation process, the variations being caused by differences in the imaging conditions for each imaging; and an output process for outputting the dynamic analysis result corrected by the correction process. the correction process corrects the kinetic analysis result based on a conversion formula for correcting the kinetic analysis result; the conversion formula is a formula that approximates a relationship between a spatial direction feature amount and a threshold value based on a plurality of spatial direction feature amounts obtained by different dynamic imaging and threshold values ​​that digitize states of parts corresponding to pixels that indicate the spatial direction feature amounts, The correction process is a program for correcting the dynamic analysis result by substituting the spatial direction feature amount into the transformation formula, calculating a threshold value, calculating a multiplier required to make the calculated threshold value a target value as a correction value, and multiplying the dynamic analysis result by the correction value.

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