Dynamic analysis device, dynamic analysis method, and program

Abstract

To provide a dynamic analysis device, etc. which enables even a medical doctor who is not used to interpretation of a dynamic analysis image to perform diagnosis accurately.SOLUTION: A dynamic analysis device for performing dynamic analysis on a dynamic image obtained by irradiating a subject with radiation comprises: a generation unit which generates as a dynamic analysis image the difference between the signal value of each pixel of a single reference frame constituting the dynamic image and the signal value of each pixel corresponding to another frame; a detection unit which when the signal value of each pixel of the dynamic analysis image is a first threshold or less, detects the pixel as a signal lowering region showing lowering of a bloodstream; and a determination unit which determines bloodstream deficiency when the area of the detected signal lowering region is a second threshold or less.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] As one of the analytical processes for dynamic images, an analytical process has been developed that can visualize the amount of change in high-frequency signals in the lung field synchronized with the heartbeat and express minute changes in blood flow. This analytical process is effective for evaluating pulmonary embolism, etc. Patent Document 1 describes a dynamic analysis device that displays the dynamic analysis results in color or binary by coloring each signal value of the dynamic analysis results according to the magnitude of the signal value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-149901 Summary of the Invention [Problem to be solved by the invention]

[0004] However, while conventional technology displays changes in blood flow within the lung field in color or binary, doctors who are not accustomed to interpreting images have the problem that they cannot correctly assess the presence or absence of blood flow defects unless they undergo training. Also, because interpretation is subjective, there are cases where the degree of blood flow defects cannot be accurately assessed.

[0005] Therefore, in order to solve the above problem, the present invention aims to provide a dynamic analysis device, a dynamic analysis method, and a program that allow even doctors who are not accustomed to interpreting dynamic analysis images to make accurate diagnoses. [Means for solving the problem]

[0006] The dynamic analysis device according to the present invention comprises: A dynamic analysis device that performs dynamic analysis on a dynamic image obtained by irradiating a subject with radiation, a generation unit that generates a dynamic analysis image that measures blood flow based on signal values ​​of pixels of the dynamic image; a detection unit that detects each pixel of the dynamic analysis image as a signal decrease region indicating a decrease in blood flow when the signal value of the pixel is equal to or less than a first threshold; The apparatus further includes a determination unit that determines whether or not there is a blood flow defect based on a result of comparison between the detected quantitative value of the signal drop area or the area other than the signal drop area and a second threshold value.

[0007] The dynamic analysis method according to the present invention comprises: A dynamic analysis method for performing dynamic analysis on a dynamic image obtained by irradiating a subject with radiation, comprising: a generating step of generating a dynamic analysis image that measures blood flow based on signal values ​​of pixels of the dynamic image; a detection step of detecting a pixel of the dynamic analysis image as a signal decrease region indicating a decrease in blood flow when the signal value of the pixel is equal to or less than a first threshold; and a determination step of determining whether or not there is a blood flow defect based on the result of comparing the quantitative value of the detected signal drop region or non-signal drop region other than the signal drop region with a second threshold value.

[0008] The program according to the present invention comprises: A computer as a dynamic analysis device that performs dynamic analysis on dynamic images obtained by irradiating a subject with radiation, a generation unit that generates a dynamic analysis image that measures blood flow based on signal values ​​of pixels of the dynamic image; a detection unit that detects a pixel of the dynamic analysis image as a signal decrease region indicating a decrease in blood flow when the signal value of the pixel is equal to or less than a first threshold; a determination unit that determines whether or not there is a blood flow defect based on a comparison result between the detected quantitative value of the signal drop region or the non-signal drop region other than the signal drop region and a second threshold value; Function as. [Effects of the Invention]

[0009] According to the present invention, even doctors who are not accustomed to interpreting dynamic analysis images can intuitively evaluate blood flow defects and diagnose diseases without overlooking them. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of a schematic configuration of a radiation imaging system according to an embodiment of the present invention. [Figure 2] FIG. 1 is a diagram showing an example of a block diagram of a dynamic analysis apparatus according to an embodiment of the present invention. [Figure 3] 10 is a flowchart showing an example of the operation of the dynamic analysis device when determining the presence or absence of a blood flow defect using a dynamic analysis image in PH2 mode according to this embodiment. [Figure 4] 10 is a flowchart showing the flow of dynamic analysis processing in PH2 mode according to the present embodiment. [Figure 5] FIG. 10 is a diagram showing a dynamic analysis image in PH2 mode when coloring according to the present embodiment is performed. [Figure 6] FIG. 10 is a diagram showing an example of a dynamic analysis image in which each pixel is colored according to the magnitude of the signal value after gain adjustment processing according to the present embodiment. [Figure 7] FIG. 10 is a diagram showing an example of a dynamic analysis image when a signal drop region according to the present embodiment is subjected to an enhancement process. [Figure 8] 10A and 10B are diagrams showing an example of a dynamic analysis image in PH2 mode, a dynamic analysis image showing a signal drop area, and statistical information displayed on the display unit according to the present embodiment. [Figure 9] FIG. 10 is a diagram showing an example of a method for setting a first threshold value and the like according to a first modified example. [Figure 10] FIG. 10 is a diagram showing an example of a method for setting a first threshold value and the like according to a second modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0012] [Configuration example of radiation imaging system 100] FIG. 1 is a diagram showing an example of a schematic configuration of a radiation imaging system 100 according to this embodiment. The radiation imaging system 100 includes a radiation generating device 1, a radiation image capturing device 2, a console 3, and a dynamic analysis device 4. Hereinafter, the radiation generating device 1 may be referred to as the generating device 1, and the radiation image capturing device 2 may be referred to as the capturing device 2. The generating device 1, the capturing device 2, the console 3, and the dynamic analysis device 4 are communicably connected to each other via a network N. Examples of the network N include a LAN, a WAN, or the Internet. LAN is an abbreviation for Local Area Network. WAN is an abbreviation for Wide Area Network. The communication method of the network N may be wired communication or wireless communication.

[0013] The generating device 1 includes a generator 11, an exposure switch 12, and a radiation source 13. Based on the operation of the exposure switch 12, the generator 11 applies a voltage according to preset imaging conditions to the radiation source 13, which includes, for example, a tube. The generator 11 may have an operation unit that accepts input of irradiation conditions, etc. When a voltage is applied from the generator 11, the radiation source 13 generates radiation R at a dose according to the applied voltage. The radiation R is, for example, X-rays.

[0014] The generator 1 generates radiation R in a manner corresponding to the type of radiographic image, for example, a still image or a dynamic image. Specifically, in the case of a still image, the generator 1 irradiates radiation R only once per pressing of the exposure switch 12. In the case of a dynamic image, the generator 1 acquires a series of images of the subject S through dynamic imaging, in which pulsed radiation such as X-rays is repeatedly irradiated to the subject S at predetermined time intervals in response to a single imaging operation. Repeated irradiation of pulsed radiation at predetermined time intervals is called pulse irradiation. Dynamic imaging also includes acquiring a series of images of the subject S by continuously irradiating the subject S with a low dose rate without interruption in response to a single imaging operation. Continuous irradiation of radiation without interruption is called continuous irradiation. A series of images acquired through dynamic imaging is called a dynamic image. Each of the images constituting a dynamic image is called a frame image. Dynamic imaging includes video imaging, but does not include capturing still images while displaying the video. Dynamic imaging includes video, but does not include images acquired by capturing still images while displaying the video.

[0015] The imaging device 2 generates digital image data showing the imaging region of the subject S. For example, a portable FPD is used as the imaging device 2. FPD is an abbreviation for Flat Panel Detector. The imaging device 2 may be configured integrally with the generating device 1.

[0016] Although not shown, the imaging device 2 includes, for example, an imaging element, a sensor board, a scanning unit, a readout unit, a control unit, and a communication unit. The imaging element generates an electric charge according to the dose of radiation R when exposed to the radiation. The sensor board has switch elements arranged two-dimensionally (in a matrix) that accumulate and release electric charge. The scanning unit switches each switch element on and off. The readout unit reads out the amount of electric charge released from each pixel as a signal value. The control unit generates image data of the radiation image from the multiple signal values ​​read out by the readout unit. The image data includes still image data or moving image data. The communication unit transmits the generated image data and various signals to other devices such as the console 3, and receives various information and signals from other devices.

[0017] The console 3 sets imaging conditions for the generator 1 and the imaging device 2, etc., and controls the reading operation of the radiation images captured by the imaging device 2. The console 3 is also called an imaging control device, and is configured, for example, by a personal computer, etc.

[0018] The imaging conditions include, for example, patient conditions related to the subject S, irradiation conditions related to the irradiation of radiation R, and image reading conditions related to the image reading of the imaging device 2. The patient conditions include, for example, the imaging region, imaging direction, and physique. The irradiation conditions include, for example, tube voltage (kV), tube current (mA), irradiation time (ms), and current-time product (mAs value). The image reading conditions include, for example, pixel size, image size, and frame rate. The console 3 may automatically set the imaging conditions based on order information acquired from an HIS / RIS, etc. Alternatively, the console 3 may manually set the imaging conditions by a user, such as a doctor or radiologist, operating an operation unit 41, which will be described later.

[0019] The dynamic analysis device 4 performs dynamic analysis on dynamic images acquired from other devices such as the imaging device 2 and the console 3. For example, as one type of dynamic analysis, the dynamic analysis device 4 performs a process of visualizing the amount of change in high-frequency signals (blood flow volume change) in the lung field synchronized with the heartbeat, and expressing minute changes in blood flow. In this embodiment, this dynamic analysis process is called PH2 mode. Specifically, the dynamic analysis device 4 calculates the difference between the signal value of a pixel in a predetermined region extracted from the reference frame of the dynamic image and the signal value of a pixel in a corresponding predetermined region of another frame image as the blood flow feature of each pixel. The dynamic analysis device 4 displays the results of the dynamic analysis of the dynamic image on the screen of the display unit 42.

[0020] [Configuration example of dynamic analysis device 4] Next, the configuration of the dynamic analysis device 4 according to this embodiment will be described. Fig. 2 is a diagram showing an example of a block diagram of the dynamic analysis device 4 according to this embodiment.

[0021] The dynamic analysis device 4 includes a control unit 40, an operation unit 41, a display unit 42, a storage unit 43, and a communication unit 44. The control unit 40, the operation unit 41, the display unit 42, the storage unit 43, and the communication unit 44 are connected to each other via wiring such as a bus 45.

[0022] The control unit 40 includes, for example, a processor such as a CPU that performs calculations and control, and a memory. CPU is an abbreviation for Central Processing Unit. The control unit 40 executes a program P (described later) stored in, for example, a memory such as a RAM, the storage unit 43, etc., thereby performing dynamic analysis processing on dynamic images, determining the presence or absence of blood flow defects from the dynamic analysis images, etc. The control unit 40 may include electronic circuits such as ASIC and FPGA. ASIC is an abbreviation for Application Specific Integrated Circuit, and FPGA is an abbreviation for Field Programmable Gate Array.

[0023] In this embodiment, the control unit 40 functions as a generator, corrector, detector, determiner, and output unit. The processor of the control unit 40 executes a program P stored in the memory unit 43, etc., thereby realizing the functions of the generator, corrector, detector, determiner, and output unit. The generator generates a dynamic analysis image that measures blood flow based on the signal values ​​of pixels in the dynamic image. More specifically, the generator calculates the difference between the signal values ​​of each pixel in one reference frame constituting the dynamic image and the signal values ​​of corresponding pixels in other frames as part of the dynamic analysis process, thereby generating a dynamic analysis image in PH2 mode. The corrector improves the contrast of the generated dynamic analysis image by correcting for variations in the imaging conditions between each imaging session. The detector detects each pixel in the dynamic analysis image as a signal drop region indicating a decrease in blood flow value when the signal value of that pixel is equal to or less than a first threshold value. The first threshold value is a threshold value used to determine whether each pixel in the dynamic analysis image corresponds to a signal drop region indicating a decrease in blood flow. The determination unit determines whether or not there is a blood flow defect based on the result of comparing a quantitative value, such as area, of the detected signal drop region or a non-signal drop region other than the signal drop region with a second threshold. When the quantitative value is area, the second threshold is a threshold for determining whether the area of ​​the signal drop region or the like corresponds to a blood flow defect or the like. When it is determined that there is a blood flow defect in the dynamic image, the output unit outputs determination information regarding the blood flow defect to the display unit 42 or the like.

[0024] The operation unit 41 includes, for example, a mouse, a keyboard, switches, buttons, etc. The operation unit 41 may be, for example, a touch panel integrally combined with a display, or an interface that accepts voice input. The operation unit 41 accepts instructions corresponding to various input operations from the user, converts the accepted instructions into operation signals, and outputs the signals to the control unit 40.

[0025] The display unit 42 is, for example, a display such as a liquid crystal display or an organic EL display. EL is an abbreviation for Electro Luminescence. The display unit 42 displays an image that has undergone predetermined analysis processing, a GUI for accepting various input operations from the user, and the like. GUI is an abbreviation for Graphical User Interface. Specifically, the display unit 42 displays a dynamic analysis image obtained by dynamic analysis of the dynamic image, and determination information including the presence or absence of blood flow defects and the like determined based on the dynamic analysis image.

[0026] The storage unit 43 includes any storage module, such as an HDD, SSD, ROM, and RAM. HDD is an abbreviation for Hard Disk Drive. SSD is an abbreviation for Solid State Drive. ROM is an abbreviation for Read Only Memory. The storage unit 43 stores, for example, system programs, application programs, and various data. Specifically, the storage unit 43 stores a program P for executing a dynamic analysis process for a dynamic image, a determination process for determining the presence or absence of a blood flow defect or the like from the dynamic analysis image, and the like. The storage unit 43 may also store a first threshold for determining whether each pixel of the dynamic analysis image corresponds to a signal drop region that indicates a drop in blood flow, and a second threshold for determining whether the area of ​​the signal drop region corresponds to a blood flow defect or the like.

[0027] The communication unit 44 includes, for example, a communication module including a NIC, a receiver, and a transmitter. NIC is an abbreviation for Network Interface Card. The communication unit 44 communicates various information and image data with the generation device 1, the imaging device 2, the console 3, etc. via the network N.

[0028] [Example of dynamic analysis device 4 operation] Next, the flow of the dynamic analysis processing method according to this embodiment will be described. Fig. 3 is a flowchart showing an example of the operation of the dynamic analysis device 4 when determining the presence or absence of blood flow defects using a dynamic analysis image in PH2 mode according to this embodiment. Note that the following describes a case where the processing region of the dynamic image is a lung field region. Furthermore, as the dynamic analysis processing, a case where the PH2 mode is executed, which visualizes the amount of change in high-frequency signals in the lung field synchronized with the heartbeat and expresses minute changes in blood flow volume, will be described.

[0029] The control unit 40 acquires dynamic images from other devices such as the imaging device 2 and the console 3 via the communication unit 44 (step S1). After acquiring the dynamic images, the control unit 40 proceeds to step S2.

[0030] The control unit 40 executes a dynamic analysis process in PH2 mode on the acquired dynamic image (step S2). To execute the dynamic analysis process in PH2 mode, the control unit 40 proceeds to a subroutine shown in FIG. 4. FIG. 4 is a flowchart showing the flow of the dynamic analysis process in PH2 mode according to this embodiment. Note that the dynamic analysis process in PH2 mode can be implemented using, for example, the technology disclosed in Japanese Patent Application Laid-Open No. 2002-222144.

[0031] As shown in FIG. 4, the control unit 40 sets an analysis area RA in each frame of the acquired dynamic image (step S20). The analysis area RA is an area that coincides with an area including a processing area RP set in the processing area setting process described below. The analysis area RA includes a lung field area. The analysis area RA may be acquired, for example, by using a trained model that has been machine-learned to output the analysis area RA for the acquired dynamic image. In this case, the control unit 40 inputs the dynamic image of the lung field area into the trained model, and acquires, as an output result from the trained model, a dynamic image of the analysis area RA in which multiple contour points are added on the contour line of the lung field area. The analysis area RA may be set by another automatic method or manually by the user.

[0032] Next, the control unit 40 divides the set analysis region RA of each frame constituting the dynamic image into a plurality of block regions RB each having a size of one pixel or more. For example, the control unit 40 divides the analysis region RA into rectangular block regions RB of 10 mm x 10 mm arranged in a matrix. After the control unit 40 sets the analysis region, it proceeds to step S21.

[0033] The control unit 40 generates a dynamic analysis image G1 in PH2 mode by performing dynamic analysis on the dynamic image (step S21). Step S21 corresponds to a generation step. For example, the control unit 40 calculates the difference between the signal value of a pixel in one reference frame constituting the dynamic image and the signal value of a pixel corresponding to a pixel in another frame. The control unit 40 may set a different frame as the reference frame for each set block region RB. The reference frame may be, for example, the frame showing the lowest signal value or the frame showing the highest signal value in a predetermined RPI (cardiac region) among multiple frames. Note that, although a dynamic image is generated as the dynamic analysis image G1, a still image may also be generated as the dynamic analysis image G1, or a correlation value may also be generated as the dynamic analysis image G1.

[0034] Here, for patients with low blood flow, the amplitude of the signal waveform in the dynamic analysis image G1 is small, and the contrast is low when each pixel is displayed in color. FIG. 5 is a diagram showing the dynamic analysis image G1 obtained in step S21 according to this embodiment when coloring the dynamic analysis image. For example, a short patient will have low blood flow. In this case, the color contrast in the dynamic analysis image G1 shown in FIG. 5 is low, and it may be difficult to accurately determine whether or not there is a blood flow defect. Therefore, in this embodiment, gain adjustment is performed on the generated dynamic analysis image G1 to improve the color contrast of the dynamic analysis image G1. After completing generation of the dynamic analysis image G1, the control unit 40 proceeds to step S22.

[0035] The control unit 40 executes a feature calculation process (step S22). The feature calculation process includes a processing region setting process, a time direction feature calculation process, and a space direction feature calculation process. First, the control unit 40 executes a processing region setting process for setting a processing region RP in the dynamic image. For example, if the subject S is the chest of a subject and the dynamic analysis image G1 is an analysis result related to pulmonary blood flow, the control unit 40 sets the lung field region, hilar region, cardiac region, aortic arch region, or arterial region as the processing region RP.

[0036] Next, the control unit 40 executes a time direction feature calculation process. The control unit 40 calculates, for each pixel from the dynamic analysis image G1, the maximum, median, minimum, integrated value, or average value of the change in signal value over time as the time direction feature. For example, the control unit 40 sets the minimum value of the change in signal value over time as the time direction feature. The control unit 40 creates a summarized image IS in which the calculated time direction feature values ​​for each pixel are collected into one image.

[0037] Next, the control unit 40 executes a spatial direction feature calculation process. The control unit 40 calculates a maximum value, a median value, a minimum value, an integrated value, or an average value as a spatial direction feature from the summarized image IS calculated in the time direction feature calculation process. For example, the control unit 40 sets the minimum value of the time direction feature as the spatial direction feature. After the control unit 40 finishes calculating the feature, the process proceeds to step S23.

[0038] The control unit 40 executes a correction value calculation process (step S23). The control unit 40 calculates the correction value based on the spatial direction feature calculated in the spatial direction feature calculation process and a conversion formula stored in the storage unit 43. The conversion formula is for correcting the dynamic analysis image G1. The conversion formula may be calculated based on a dynamic analysis image obtained by performing dynamic analysis on at least two dynamic images. Specifically, the conversion formula is a linear approximation of the distribution of a scatter diagram plotting the relationship between multiple spatial direction feature values ​​obtained by different dynamic imaging and threshold values ​​(gain values) that digitize the actual state of blood flow when visually observing a region corresponding to a pixel indicating the spatial direction feature value. The conversion formula is expressed in the form of the following formula (1). Threshold = constant a × spatial direction feature value − constant b (1)

[0039] Next, the control unit 40 calculates a threshold value by substituting the spatial direction feature calculated in the feature calculation process into the conversion formula (1). The control unit 40 sets the multiplier required to make the calculated threshold value the target value as the correction value. In other words, the correction value is a value obtained by dividing the target value by the threshold value. Note that the conversion formula does not have to be stored in advance, but may be newly calculated. The conversion formula may be updated in accordance with newly acquired dynamic images, etc. After the control unit 40 has finished calculating the correction value, the process proceeds to step S24.

[0040] The control unit 40 corrects the dynamic analysis image G1 based on the correction value calculated in the correction value calculation process (step S24). Specifically, the control unit 40 multiplies the dynamic analysis image G1, such as the calculated difference value, evaluation value, correlation value, etc. of each pixel, by the correction value, and generates a corrected dynamic analysis image G2. By performing the correction process, the control unit 40 can correct variations in the generated dynamic analysis image G1 due to differences in shooting conditions for each shooting. The control unit 40 may correct the summarized image IS created in the time direction feature calculation process based on the correction value.

[0041] The control unit 40 colors each pixel of the dynamic analysis image G2 after gain adjustment. Specifically, the control unit 40 colors each pixel of the lung field region of the acquired corrected dynamic analysis image G2 according to the magnitude of the signal value of each pixel. As a coloring method, for example, a table in which the signal value of each pixel corresponds to each RGB level can be used. In this embodiment, the corrected dynamic analysis image G2 is expressed in color using a 511-level gradation from black (R:0, G:0, B:0) to red (R:255, G:0, B:0) to yellow (R:255, G:255, B:0). In this case, pixels with less blood flow are expressed in black, and pixels with more blood flow are expressed in red and yellow.

[0042] FIG. 6 shows an example of a dynamic analysis image G2 colored according to the signal value of each pixel after gain adjustment according to this embodiment. In the dynamic analysis image G2, areas close to the heart have a high blood flow volume and a high signal value, and are therefore represented in yellow. Note that in FIG. 6, yellow is represented in white for convenience. On the other hand, areas farther from the heart have a low blood flow volume and a low signal value, and are therefore represented in black. Furthermore, in the dynamic analysis image G2, areas where diseases such as blood flow defects occur are represented in black because of the low blood flow volume and low signal value. By performing gain adjustment, the color contrast can be increased even in patients with low blood flow, making it relatively easier to determine the presence or absence of blood flow defects. After coloring the corrected dynamic analysis image, the control unit 40 terminates the subroutine and proceeds to step S3 of FIG. 3.

[0043] As shown in FIG. 3, the control unit 40 classifies each pixel in the lung field region of the acquired dynamic analysis image G2 into pixels with signal values ​​equal to or less than a first threshold and pixels with signal values ​​exceeding the first threshold (step S4). In other words, the control unit 40 extracts pixels with signal values ​​equal to or less than the first threshold from among the multiple pixels in the lung field region. Step S4 corresponds to a detection step. The first threshold can be set, for example, based on a red-red scale close to black, which indicates reduced blood flow and a high possibility of blood flow deficiency. The red-red scale close to black corresponds, for example, to 15% of the 511 color scales, or (R: 76, G: 0, B: 0) in RGB display. The correspondence between the occurrence of blood flow deficiency and the magnitude of the signal value of each pixel in the dynamic image can be obtained, for example, using the diagnostic results of previous dynamic images. Note that although the color representation is 511 scales, the dynamic analysis image G2 may also be represented using a color scale from 0 to 100, i.e., a 101-scale gradation. In this case, 15 scales can be set as the first threshold representing blood flow deficiency. Furthermore, the first threshold value is not limited to 15% of the total color range, and can be changed as needed depending on the purpose of the test. For example, if the purpose is a screening test, the first threshold value can be set to a smaller value because higher sensitivity is required.

[0044] The control unit 40 adds each pixel of the kinetic analysis image G2 that is classified as being equal to or less than the first threshold to a signal drop region that indicates that the blood flow is below a certain reference value (step S5). After completing the process of adding the corresponding image to the signal drop region, the control unit 40 proceeds to step S6.

[0045] Meanwhile, the control unit 40 adds each pixel of the dynamic analysis image G2 that exceeds the classified first threshold to a non-signal drop region, which indicates that the blood flow exceeds a certain reference value (step S11). Areas other than the signal drop region in the dynamic analysis image G2 become non-signal drop regions. After completing the process of adding the corresponding image to the non-signal drop region, the control unit 40 proceeds to step S6.

[0046] The control unit 40 generates a dynamic analysis image G3 by highlighting each pixel that corresponds to the signal drop region on the dynamic analysis image G2. Specifically, the control unit 40 applies a color corresponding to the signal drop region to each pixel added to the signal drop region. The color corresponding to the signal drop region is a color different from the color expressed in FIG. 6 and is not particularly limited, but is, for example, yellow-green. In contrast, the control unit 40 does not apply a new color to each pixel added to the non-signal drop region, but maintains the color applied in step S24.

[0047] FIG. 7 is a diagram showing an example of a dynamic analysis image G3 in which signal drop regions according to this embodiment have been enhanced. In FIG. 7, yellow-green signal drop regions are shown hatched for convenience. In the dynamic analysis image G3, the peripheral areas of the right and left lungs within the lung field are primarily enhanced in yellow-green as signal drop regions. This allows users, such as doctors, to accurately and quickly identify areas in the lung field of the dynamic analysis image G3 where blood flow defects have occurred.

[0048] The control unit 40 calculates the area of ​​the signal drop region in the processing region of the dynamic analysis image G3 (step S7). For example, the control unit 40 calculates an area ratio, which is the ratio of the area of ​​the signal drop region to the total area of ​​the processing region of the dynamic image analysis. After calculating the area of ​​the signal drop region, the control unit 40 proceeds to step S8.

[0049] The control unit 40 determines whether the area, which is the calculated quantitative value of the signal drop region, is equal to or greater than a second threshold (step S8). Step S8 corresponds to the determination step. The second threshold can be set to, for example, 20%. This is because when the ratio of the area of ​​the signal drop region to the total area of ​​the processing region of the dynamic analysis image G3 is 20% or more, there is generally a high possibility of blood flow deficiency. Note that the second threshold is not limited to 20% and can be changed as appropriate depending on the purpose of the test. For example, if the purpose is a screening test, the second threshold may be set to a smaller value because increased sensitivity is required.

[0050] If the control unit 40 determines that the calculated area ratio, which is the ratio of the area of ​​the signal drop region to the total area of ​​the processing region of the dynamic analysis image G3, is equal to or greater than the second threshold, the process proceeds to step S9. In this case, the control unit 40 determines that a blood flow defect has occurred in the processing region of the acquired dynamic analysis image G3 (step S9), and proceeds to step S10. At this time, the control unit 40 may determine that there is a possibility of pulmonary embolism if there is no abnormality in the background lung in the processing region of the dynamic analysis image G3. Conversely, the control unit 40 may determine that there is a possibility of a disease other than pulmonary embolism if there is an abnormality in the background lung in the processing region of the dynamic analysis image G3.

[0051] On the other hand, if the control unit 40 determines in step S8 that the area of ​​the signal drop region within the calculated processing region is less than the second threshold, the process proceeds to step S12. In this case, the control unit 40 determines that no blood flow defect has occurred in the predetermined region of the acquired dynamic analysis image G3 (step S12), and the process proceeds to step S10.

[0052] The control unit 40 outputs the PH2 mode dynamic analysis image G2, the dynamic analysis image G3 showing the signal drop region, and determination information regarding blood flow defects, etc. to the display unit 42 (step S10). The determination information includes, for example, statistical information I of the signal drop region. The determination information may also include the presence or absence of blood flow defects, the name of a disease such as pulmonary embolism, etc.

[0053] FIG. 8 shows an example of a dynamic analysis image G2 in PH2 mode, a dynamic analysis image G3 in which the signal drop region has been enhanced, and statistical information I, all displayed on the display unit 42 according to this embodiment. The examination screen 240 of the display unit 42 displays the dynamic analysis image G2 in PH2 mode, a dynamic analysis image G3 generated from the dynamic analysis image G2, and statistical information I related to the signal drop region. The dynamic analysis image G2 is a dynamic image in PH2 mode with gain adjustment and is displayed, for example, on the left side of the screen. The dynamic analysis image G3 is a still image in which the signal drop region, where blood flow in the lung field is reduced, is highlighted and is displayed, for example, on the right side of the screen. Note that the dynamic analysis image G3 is not limited to a still image and may be a moving image. The dynamic analysis image G3 has a threshold adjustment slider H for adjusting the first threshold. Adjusting the threshold adjustment slider H changes the sensitivity for determining whether or not an area corresponds to a signal drop region. The statistical information I is displayed, for example, below the dynamic analysis image G3. The statistical information I displays, for example, the area and occupancy rate of the signal reduction region for each of the right and left lungs in the lung field region in the dynamic analysis image G3. The statistical information I may also include determination information indicating the presence or absence of blood flow defect, the name of a disease such as pulmonary embolism, etc.

[0054] The display content of the display unit 42 may be at least one of a dynamic analysis image G2 in PH2 mode, a dynamic analysis image G3 in which a signal drop area is highlighted, and statistical information I. Furthermore, the display of the signal drop area in the dynamic analysis image G3 may be turned on and off. Furthermore, multiple dynamic analysis images G3 including signal drop areas determined using multiple first thresholds may be displayed side by side on the screen of the display unit 42. Furthermore, adjustment of the first threshold and the like is not limited to the threshold adjustment slider H. For example, the first threshold may be adjustable by directly inputting a numerical value or by operating a numerical value increase / decrease button.

[0055] In the above-described embodiment, the first threshold is set based on the level of color display when each pixel of the lung field region of the dynamic analysis image G2 after gain adjustment is displayed in color. However, this is not limiting. For example, the first threshold may be set based on the amount of X-ray transmission for each pixel of the lung field region of the dynamic analysis image before gain adjustment. Specifically, the first threshold can be set as follows: Generally, in areas where blood vessel pulsation is sufficient, such as the origin of the pulmonary artery, blood vessel pulsation changes by approximately 6%. In this case, if the change in blood vessel pulsation falls below 0.9% of approximately 6%, there is a high possibility of a blood flow defect. Therefore, the first threshold can be set to 0.9%. Furthermore, if the change in blood vessel pulsation of approximately 6% is expressed as 100, 0.9% corresponds to 15% of 6%, so the first threshold may be set to 15.

[0056] The method for determining whether or not a blood flow defect has occurred from the dynamic analysis image G3 is not limited to the above-described method. For example, in the above example, the presence or absence of a blood flow defect is determined using the area of ​​the signal drop region, but it may also be determined using the area of ​​the non-signal drop region. In this case, the second threshold value can be set to, for example, less than 80%. The control unit 40 can determine that the signal drop region is a region where a blood flow defect has occurred when the area of ​​the non-signal drop region is less than 80%. As another determination method, for example, the ratio of the signal drop region to the non-signal drop region can be used. The ratio of the signal drop region to the non-signal drop region is, for example, 1:4. In this case, the control unit 40 determines that a blood flow defect has occurred when the ratio of the signal drop region to the non-signal drop region is 1:4 (1 / 4 or more). Alternatively, the presence or absence of a blood flow defect may be determined using a value obtained by dividing the ratio of the signal drop region to the non-signal drop region. In this case, the second threshold value is set to, for example, 0.25 or more.

[0057] According to this embodiment, even physicians, such as private practitioners and trainees, who are not accustomed to interpreting dynamic analysis images G2 and the like in PH2 mode can intuitively evaluate blood flow defects because the dynamic analysis image G3 showing the signal drop areas and statistical information I related to blood flow defects are displayed on the display unit 42. This allows for diagnosis without overlooking any diseases. Furthermore, according to this embodiment, the area and occupancy rate of the signal drop areas in the dynamic analysis image G3 are displayed on the display unit 42, allowing for objective determination of the presence or absence of disease. For example, by comparing the area, etc. of the signal drop areas with those of previous dynamic analysis images, it is possible to determine whether the blood flow defect has recovered or worsened.

[0058] [First Modification] In the above-described embodiment, a single first threshold value is used to determine the signal drop region of the processing region. However, multiple first threshold values ​​may be set depending on the distance from a reference position, such as the center of the processing region. This is because, for example, the blood flow rate in the pulmonary artery generally decreases from the center of the large blood vessels toward the periphery just before the capillaries. Blood vessels closer to the heart are larger and therefore have a greater blood flow. Blood vessels further from the heart are smaller and therefore have a smaller blood flow. Therefore, setting the first threshold value taking into account the actual blood flow in a state without a disease such as a blood flow defect may result in more accurate determination of the signal drop region. The first threshold value may also be changed depending on the imaging position. For example, in the case of upright imaging, the first threshold value may be set depending on the vertical position. The first threshold value is set higher at the lower side and lower at the upper side. This is because, in the upright position, gravity increases blood flow in the lower side and decreases blood flow in the upper side.

[0059] In the first modification, for example, the lung field region of the dynamic analysis image G2 is divided into multiple concentric regions based on the center of the lung field region, and a different first threshold value is set for each divided region. Note that components having the same configuration and function as those in the above embodiment are denoted by the same reference numerals and will not be described in detail.

[0060] FIG. 9 is a diagram showing an example of a method for setting the first threshold value and the like according to the first modification. In the first modification, the lung field of the dynamic analysis image G2 is divided concentrically from the center of the lung field outward into a first region R1, a second region R2, a third region R3, a fourth region R4, and a fifth region R5. The heart is located approximately at the center of the lung field. The first region R1 is the region closest to the center of the lung field, and the fifth region R5 is the region farthest from the center of the lung field. Next, different first threshold values ​​are set for the divided first region R1, the second region R2, the third region R3, the fourth region R4, and the fifth region R5. Specifically, the first threshold value is set smaller as the distance from the center of the lung field increases. In other words, the first threshold value is set to decrease in the order of the first region R1, the second region R2, the third region R3, the fourth region R4, and the fifth region R5.

[0061] The control unit 40 determines whether or not the pixels in each divided region of the lung field of the dynamic analysis image correspond to a signal drop region using a first threshold value set for each region. For example, the control unit 40 determines whether or not each pixel in a first region R1 of the lung field corresponds to a signal drop region using the first threshold value set for the first region R1. Similarly, the control unit 40 determines whether or not each pixel in a second region R2, a third region R3, a fourth region R4, and a fifth region R5 corresponds to a signal drop region using the first threshold value set for each region.

[0062] Furthermore, when the lung field region of the dynamic analysis image G2 is divided into multiple concentric regions based on the center of the lung field region, a second threshold value may be set for each divided region. Specifically, a second threshold value is set for each of the first region R1, second region R2, third region R3, fourth region R4, and fifth region R5 shown in FIG. 9. The second threshold value may be set based on the area ratio of the signal reduction region to the total area of ​​the divided region in a dynamic analysis image obtained by another dynamic imaging. The second threshold value may be set arbitrarily, but may be set to 20%, for example.

[0063] The control unit 40 calculates the signal drop area for each of the first, second, third, fourth, and fifth regions R1, R2, R3, R4, and R5 obtained by dividing the lung field in the dynamic analysis image G2. The control unit 40 then determines whether the area of ​​the calculated signal drop area for each region is equal to or greater than a second threshold. Specifically, the control unit 40 determines whether the area of ​​the signal drop area for the first region R1 is equal to or greater than a second threshold set for the first region R1. Similarly, the control unit 40 determines whether the area of ​​the signal drop area for each of the second, third, fourth, and fifth regions R2, R3, R4, and R5 is equal to or greater than a second threshold set for the respective region.

[0064] According to the first modification, the lung field region of the dynamic analysis image is divided into multiple regions according to the distance from a reference position such as the heart, and a first threshold and a second threshold are set for each divided region. This makes it possible to determine whether a region corresponds to a signal drop region and whether a blood flow defect exists, taking into account the original blood flow in a state without a disease such as a blood flow defect. As a result, it is possible to prevent an area with originally low blood flow from being mistakenly diagnosed as a signal drop region or having a blood flow defect.

[0065] [Second Modification] In the second modification, multiple regions are provided for the left and right lungs in the lung field region, with the center of the lung field as a reference, and different first threshold values ​​are set for each region. Note that components having the same configurations and functions as those in the above embodiment are denoted by the same reference numerals and will not be described in detail.

[0066] FIG. 10 is a diagram showing an example of a method for setting the first threshold value and other parameters according to the second modification. In the second modification, the right lung in the lung field region of the dynamic analysis image G2 is divided from the center outward into a first region T1 and a second region T2. ​​Similarly, the left lung in the lung field region of the dynamic analysis image G2 is divided from the center outward into a third region T3 and a fourth region T4. The first region T1 and the third region T3 are the regions closest to the center of the lung field, and the second region R2 and the fourth region T4 are the regions farthest from the center of the lung field. In this embodiment, different first threshold values ​​are set for the divided first region T1, second region T2, third region T3, and fourth region T4, and the first threshold value is set to a smaller value depending on the distance from the center of the lung field. The first region T1 and the third region T3 are approximately the same distance from the center of the lung field, so the same value may be used. Similarly, the second region T2 and the fourth region T4 are approximately the same distance from the center of the lung field, so the same value may be used.

[0067] The control unit 40 determines whether or not the pixels in each divided region of the lung field of the dynamic analysis image correspond to a signal drop region using a first threshold value set for each region. For example, the control unit 40 determines whether or not the pixels in the first region R1 of the lung field correspond to a signal drop region using a first threshold value set for the first region T1. Similarly, the control unit 40 determines whether or not the pixels in the second region T2, the third region T3, and the fourth region T4 correspond to a signal drop region using a first threshold value set for each region.

[0068] Furthermore, when the lung field region of the dynamic analysis image G2 is divided into multiple regions for the right lung and the left lung based on the center of the lung field region, a second threshold value may be set for each divided region. Specifically, a second threshold value is set for each of the first region R1, second region R2, third region R3, and fourth region R4 shown in FIG. 10. The second threshold value may be set based on the area ratio of the signal reduction region to the total area of ​​the divided region in a dynamic analysis image obtained by another dynamic imaging. The second threshold value may be set arbitrarily, but may be set to 20%, for example.

[0069] The control unit 40 calculates the signal drop areas in the first region R1, second region R2, third region R3, and fourth region R4 obtained by dividing the lung field region of the dynamic analysis image G2. The control unit 40 then determines whether the area of ​​the calculated signal drop area in each region is equal to or greater than a second threshold. Specifically, the control unit 40 determines whether the area of ​​the signal drop area in the first region R1 is equal to or greater than a second threshold set for the first region R1. Similarly, the control unit 40 determines whether the area of ​​the signal drop area in each of the second region R2, third region R3, and fourth region R4 is equal to or greater than the second threshold set for the respective region.

[0070] According to the second modification, the lung field region of the dynamic analysis image is divided into multiple regions according to the distance from a reference position such as the heart, and a first threshold and a second threshold are set for each divided region. This makes it possible to determine whether a region corresponds to a signal drop region and whether a blood flow defect exists, taking into account the original blood flow in a state without a disease such as a blood flow defect. As a result, it is possible to prevent an area with originally low blood flow from being erroneously diagnosed as a signal drop region or having a blood flow defect.

[0071] While the preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the technical scope of the present disclosure is not limited to such examples. Furthermore, various modifications and improvements will naturally fall within the technical scope of the present disclosure, provided that they are within the scope of the technical ideas described in the claims of those skilled in the art. Specifically, in the above-described embodiment, after performing gain adjustment on the generated dynamic analysis image, the signal drop area in the processing area is detected and it is determined whether or not a blood flow defect has occurred, but this is not limited to this. For example, it is also possible to detect the signal drop area in the processing area for a dynamic analysis image that has not undergone gain adjustment and determine whether or not a blood flow defect has occurred.

[0072] In the above-described embodiment, the areas of the signal drop regions and non-signal drop regions are used to determine whether or not a blood flow defect has occurred from the dynamic analysis image G3, but this is not limiting. For example, the signal values ​​of the signal drop regions and non-signal drop regions of the dynamic analysis image G3 may be measured, and the average, standard deviation, and integral value may be calculated from the measurement results of each signal value. The control unit 40 can determine whether or not a blood flow defect has occurred based on the results of comparing the quantitative value obtained by the calculation with a second threshold value preset according to the quantitative value. [Explanation of symbols]

[0073] 4 Dynamic analysis device 40 control unit (generation unit, detection unit, determination unit, correction unit, output unit) 42 Display section 100 Radiography System G1,G2,G3 dynamic analysis images I Statistical information (judgment information) P Program

Claims

1. A dynamic analysis device that performs dynamic analysis on a dynamic image obtained by irradiating a subject with radiation, a generation unit that generates a dynamic analysis image that measures blood flow based on signal values ​​of pixels of the dynamic image; a detection unit that, when a signal value of each pixel of the dynamic analysis image is equal to or less than a first threshold, detects the pixel as a signal decrease region indicating a decrease in blood flow value; a determination unit that determines whether or not there is a blood flow defect based on a comparison result between the quantitative value of the detected signal drop region or the non-signal drop region other than the signal drop region and a second threshold value; A dynamic analysis device comprising:

2. the second threshold is set as an area ratio of the entire area of ​​the processing region of the dynamic image to the area of ​​the signal decrease region, when the quantitative value is defined as an area. The dynamic analysis device according to claim 1 .

3. The processing area of ​​the dynamic image is divided into a plurality of areas; The second threshold is set for each divided region based on an area ratio of an area of ​​a signal decrease region to an entire area of ​​the divided region when the quantitative value is an area. The dynamic analysis device according to claim 1 .

4. the dynamic analysis image is expressed in a plurality of levels of color according to the signal value of each pixel of the dynamic analysis image; The first threshold is set to a color of a predetermined stage among a plurality of stages that represents a blood flow defect. The dynamic analysis device according to claim 1 .

5. a correction unit that corrects variations in the generated dynamic analysis image due to differences in imaging conditions for each imaging; the first threshold is set based on the dynamic analysis image after the variation has been corrected; The dynamic analysis device according to claim 4.

6. The processing area of ​​the dynamic image is divided into a plurality of areas according to a distance from a predetermined reference position; The first threshold value is set to a different value for each of the divided regions. The dynamic analysis device according to claim 1 .

7. an output unit that outputs, when the determination unit determines that there is a blood flow defect in the dynamic analysis image, determination information regarding the blood flow defect; The dynamic analysis device according to claim 1 .

8. The output unit outputs the signal decrease region in the dynamic analysis image by coloring the signal decrease region in a color different from the color of the non-signal decrease region. The dynamic analysis device according to claim 7.

9. A dynamic analysis method for performing dynamic analysis on a dynamic image obtained by irradiating a subject with radiation, comprising: a generating step of generating a dynamic analysis image that measures blood flow based on signal values ​​of pixels of the dynamic image; a detection step of detecting a pixel of the dynamic analysis image as a signal decrease region indicating a decrease in blood flow when the signal value of the pixel is equal to or less than a first threshold; a determination step of determining whether or not there is a blood flow defect based on a comparison result between the detected quantitative value of the signal drop region or the non-signal drop region other than the signal drop region and a second threshold value; A dynamic analysis method comprising:

10. A computer as a dynamic analysis device that performs dynamic analysis on dynamic images obtained by irradiating a subject with radiation, a generation unit that generates a dynamic analysis image that measures blood flow based on signal values ​​of pixels of the dynamic image; a detection unit that detects a pixel of the dynamic analysis image as a signal decrease region indicating a decrease in blood flow when the signal value of the pixel is equal to or less than a first threshold; a determination unit that determines whether or not there is a blood flow defect based on a comparison result between the detected quantitative value of the signal drop region or the non-signal drop region other than the signal drop region and a second threshold value; A program to function as a

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