Radiation image analysis device, radiation image processing method, and radiation image processing program

Abstract

Even after performing registration between frame images, accurate analysis results can be obtained. [Solution] The radiation image analysis device comprises: a first processing unit that performs a first processing on each of a plurality of frame images included in the radiation dynamic image of the target area of ​​a subject, which reduces the components of structures different from the target area in the frame image; a second processing unit that performs a second processing on the plurality of frame images, which associates the positions within the target area; and an analysis unit that analyzes the radiation dynamic image including the plurality of frame images on which the first and second processing have been performed.

Description

Technical Field

[0001] The present invention relates to a radiation image analysis apparatus, a radiation image processing method, and a radiation image processing program.

Background Art

[0002] There is known a radiation image analysis apparatus that performs kinetic analysis on a radiation dynamic image composed of a plurality of frame images obtained by irradiating a target part of a patient with radiation. For example, the radiation image analysis apparatus performs kinetic analysis on a radiation dynamic image of a patient's chest. In this case, since the lungs move due to breathing or the like, the radiation image analysis apparatus performs alignment called registration across a plurality of frame images so that the kinetic analysis can be correctly performed.

[0003] For example, in the apparatus disclosed in Patent Document 1, a first image and a second image of a target part of a patient are arranged in a template space including standard shape information of the target part, and the first image and the second image arranged in the template space are aligned.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, as disclosed in Patent Document 1, when an image of a patient's chest is transformed to fit the template space, the pixel values ​​of not only the lung field being analyzed but also the thickness of the body in front of and behind the lung field change. If the pixel values ​​of the thickness of the body in front of and behind the lung field also change, it can affect the results of the dynamic analysis and potentially lead to inaccurate results. For example, when obtaining blood flow in the blood vessels of the lung field as a result of the dynamic analysis, it is possible to obtain higher blood flow values ​​even if there are areas where blood flow is actually reduced.

[0006] The object of the present invention is to provide a radiation image analysis device, a radiation image processing method, and a radiation image processing program that can obtain accurate analysis results even when registration is performed between frame images. [Means for solving the problem]

[0007] The radiation image analysis device according to the present invention is A first processing unit performs a first processing operation on each of several frame images included in the radiodynamic image of the target area of ​​the subject, which reduces the component of a structure different from the target area in the frame image. A second processing unit performs a second processing operation to associate the positions within the target area between the plurality of frame images, An analysis unit that analyzes the radiodynamic image, which includes a plurality of frame images that have undergone the first and second processing, It is equipped with.

[0008] The radiation image processing method according to the present invention is In a radiation image analysis device, For each of the multiple frame images included in the radiodynamic image of the target area of ​​the subject, a first process is performed to reduce the components of structures different from the target area in the frame image. A second process is performed to associate the positions within the target area between the multiple frame images. The radiodynamic image, which includes multiple frame images that have undergone the first and second processing, is analyzed.

[0009] The radiation image processing program according to the present invention is In the computer of the radiation image analysis device, A first process is performed on each of the multiple frame images included in the radiodynamic image of the target area of ​​the subject, which reduces the component of structures different from the target area in the frame image. A second process is performed to associate the positions within the target area between the plurality of frame images, Analysis process for analyzing the radiodynamic image, which includes a plurality of frame images that have undergone the first and second processes, Make it run. [Effects of the Invention]

[0010] According to the present invention, accurate analysis results can be obtained even when registration is performed between frame images. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is an explanatory diagram illustrating an example of the configuration of a radiation image processing system according to an embodiment of the present invention. [Figure 2] Figure 2 is a block diagram illustrating an example of the functional configuration of the imaging control unit in a radiation imaging system that constitutes a radiation image processing system. [Figure 3] Figure 3 is a block diagram illustrating an example of the functional configuration of a radiography control device that constitutes a radiographic image processing system. [Figure 4] Figure 4 is a block diagram illustrating an example of the functional configuration of a radiation image analysis device that constitutes a radiation image processing system. [Figure 5] Figure 5 is a functional block diagram illustrating the radiation image processing method performed by the radiation image analysis device. [Figure 6] Figure 6 is a schematic diagram illustrating a conventional registration process. [Figure 7] Figure 7 is a schematic diagram illustrating the registration process in the radiation image processing method shown in Figure 5. [Figure 8] FIG. 8 is a diagram showing an analysis result of blood flow obtained by performing dynamic analysis on a dynamic image using a conventional registration process. [Figure 9] FIG. 9 is a diagram showing an analysis result of blood flow obtained by performing dynamic analysis on a dynamic image using the registration process in the radiation image processing method shown in FIG. 5. [Figure 10] FIG. 10 is a functional block diagram for explaining a modification example of the body thickness reduction process in the radiation image processing method shown in FIG. 5. MODE FOR CARRYING OUT THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0013] <Configuration of Radiation Image Processing System> FIG. 1 is a diagram for explaining a radiation image processing system 1 of the present embodiment. The radiation image processing system 1 includes a radiation image imaging system 10, a radiation imaging control device (console device) 20, a radiation image analysis device 30, an image management device 40, and a client terminal 50.

[0014] In the example shown in FIG. 1, the radiation image imaging system 10 is arranged in a shooting room, and the radiation imaging control device 20 is arranged in an operation room. The radiation image imaging system 10, the radiation imaging control device 20, the radiation image analysis device 30, the image management device 40, and the client terminal 50 are connected to each other via a communication network N. As the communication network N, for example, a communication network conforming to the DICOM (Digital Image and Communications in Medicine) standard or the like is used.

[0015] Furthermore, a radiation information terminal 60, which functions as a radiation information system, is connected to the communication network N to transmit information related to radiation examinations, such as patient examination order information, to the radiation image processing system 1. Examples of radiation information terminals 60 include RIS (Radiology Information System).

[0016] The radiography imaging system 10 performs dynamic radiography (hereinafter referred to as dynamic imaging), which is the acquisition of dynamic radiographic images (hereinafter referred to as dynamic images), based on the control of the radiography control device 20. The radiography control device 20 controls the radiography imaging system 10 based on examination order information, etc., transmitted from the radiography information terminal 60. The dynamic images generated by the radiography imaging system 10 are processed by the radiography control device 20 as described later and transmitted to the radiography image analysis device 30. The radiography image analysis device 30 performs dynamic analysis on the dynamic images. The dynamic images and the results of the dynamic analysis are transmitted to an image management device 40, which is a medical image management system, for management. The image management device 40 may be, for example, a PACS (Picture Archiving and Communication System). The dynamic images and the results of the dynamic analysis are transmitted to a client terminal 50 and viewed by medical professionals such as doctors.

[0017] In this embodiment, motion imaging refers to obtaining multiple frame images by repeatedly irradiating a subject with pulsed radiation (e.g., X-rays) at a predetermined frame rate (pulsed irradiation). Motion image refers to a series of frame images obtained by motion imaging. Motion analysis refers to analytical processing applied to motion images, and includes not only processing to analyze the movement of a subject based on the motion image, but also processing to enhance or reduce (remove) predetermined structures by analyzing the motion image.

[0018] The radiographic imaging system 10, the radiographic imaging control device 20, and the radiographic image analysis device 30 each have a processor and memory, and are a type of computer that realizes predetermined functions by reading, expanding, and executing programs stored in memory.

[0019] [Radiological imaging system 10] As shown in Figure 1, the radiation imaging system 10 comprises an imaging control unit 11, a radiation irradiation unit 12, an imaging table 13, a radiation detection unit 14, a display unit 15, and an audio output unit 16.

[0020] The imaging control unit 11 acquires setting information regarding dynamic imaging settings from the radiation imaging control device 20. Based on the setting information, the imaging control unit 11 sets the imaging conditions for dynamic imaging, and based on these imaging conditions, controls the radiation irradiation unit 12 to irradiate the patient M (subject) with radiation and perform imaging. The imaging control unit 11 is composed of a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), etc.

[0021] The setting information refers to information regarding the settings for performing dynamic imaging on patient M. For example, the setting information includes at least one of several types of dynamic analysis that the radiographic image analysis device 30 can perform on the dynamic image. If multiple types of dynamic analysis are combined, the setting information may also include information regarding that combination. The setting information is set in the radiographic imaging control device 20 (described later) by the operator of the radiographic image processing system 1, such as a radiographer.

[0022] The imaging conditions include various factors such as pulse rate, pulse width, pulse interval, number of frames per scan, radiation dose per unit time, and the patient M's physical condition (respiratory status, etc.). The pulse rate is the number of radiation exposures per second and corresponds to the frame rate of the image data. The pulse width is the radiation exposure time per exposure. The pulse interval is the time from the start of one radiation exposure to the start of the next and corresponds to the time interval (frame interval) between multiple image data. The imaging conditions can be automatically determined by the imaging control unit 11 of the radiation imaging system 10 based on the setting information.

[0023] The radiation irradiation unit 12 is positioned opposite the radiation detection unit 14, which is fixed to the imaging table 13. The radiation irradiation unit 12 irradiates radiation according to the control of the imaging control unit 11.

[0024] The radiation detection unit 14 is composed of a semiconductor image sensor such as an FPD (Flat Panel Detector). The radiation detection unit 14 has a substrate on which multiple detection elements (pixels) are arranged in a matrix to detect radiation irradiated from the radiation irradiation unit 12 according to its intensity, and to convert the detected radiation into an electrical signal and store it. Each pixel on the substrate is composed of a switching unit such as a TFT (Thin Film Transistor).

[0025] The radiation detection unit 14 controls the switching unit of each pixel based on the image reading conditions input from the radiation imaging control device 20 to read the electrical signal accumulated in each pixel and outputs intensity information for each pixel to the image generation unit 113. The image reading conditions include, for example, the frame rate, frame interval, pixel size, and image size (matrix size). The frame rate is the number of frame images acquired per second and is the same as the pulse rate. The frame interval is the time from the start of one image data acquisition operation to the start of the next frame image acquisition operation and is the same as the pulse interval.

[0026] The imaging control unit 11 and the radiation detection unit 14 are connected to each other and exchange synchronization signals to synchronize the radiation irradiation operation and the image reading operation.

[0027] In this way, the radiation imaging system 10 performs dynamic imaging of radiation images by having the radiation irradiation unit 12 irradiate radiation under the control of the imaging control unit 11, and the radiation detection unit 14 generate image data based on the intensity of the irradiated radiation.

[0028] The display unit 15 and the audio output unit 16 provide instructions to patient M regarding the posture, physical condition, respiratory condition, etc., when performing dynamic imaging of patient M. The display unit 15 is a display device such as a CRT (Cathode Ray Tube), liquid crystal display (Liquid Crystal Display), or organic EL (Electro Luminescence) display. The audio output unit 16 is an audio output device such as a speaker. The audio output unit 16 provides instructions to patient M regarding physical condition, respiratory condition, etc., for example, by auto-voice. The display unit 15 and the audio output unit 16 may each provide the same instructions to patient M, or only one of them may provide instructions.

[0029] Figure 2 is a block diagram illustrating an example of the functional configuration of the imaging control unit 11 in the radiation image acquisition system 10, which constitutes the radiation image processing system 1. The imaging control unit 11 includes a setting information acquisition unit 111, an imaging condition determination unit 112, an image generation unit 113, and a storage unit 114.

[0030] The setting information acquisition unit 111 acquires setting information from the radiation imaging control device 20.

[0031] The imaging condition determination unit 112 determines the imaging conditions for performing dynamic imaging of patient M based on the setting information. Information showing the correspondence between multiple types of dynamic analysis and imaging conditions suitable for each dynamic analysis is stored in advance in the storage unit 114. In addition, information showing the correspondence between combinations of multiple types of dynamic analysis and imaging conditions suitable for those combinations is also stored in advance in the storage unit 114. The imaging condition determination unit 112 simply needs to read the information showing the correspondence from the storage unit 114 for the dynamic analysis or combination of multiple types of dynamic analysis indicated by the setting information, and compare it with the setting information to determine the imaging conditions.

[0032] In addition, in cases such as screening or emergency situations, it may not be possible to set the dynamic analysis information. In such cases, the imaging condition determination unit 112 determines the imaging conditions by having the operator select at least one imaging condition from a plurality of predefined imaging conditions. The imaging condition determination unit 112 also has the operator select examination order information and determines the imaging conditions based on the selected examination order information. Thus, if dynamic analysis cannot be set before dynamic imaging, dynamic analysis is set after dynamic imaging with the imaging conditions selected by the operator, and dynamic analysis is performed using the radiographic image analysis device 30 (analysis by the analysis unit 314, described later).

[0033] The image generation unit 113 performs dynamic imaging of patient M based on the determined imaging conditions and generates multiple frames of radiographic images. Specifically, the image generation unit 113 controls the operation of the radiation irradiation unit 12 and the radiation detection unit 14 based on the imaging conditions, and generates image data by acquiring intensity information regarding the radiation intensity transmitted through the subject from the radiation detection unit 14 for each pixel.

[0034] As described above, the memory unit 114 pre-stores information such as the correspondence between multiple types of motion analysis and shooting conditions suitable for each motion analysis, and the correspondence between combinations of multiple types of motion analysis and shooting conditions suitable for those combinations.

[0035] [Radiography control device 20] The radiography control device 20 is, for example, a computer such as a PC (Personal Computer) or workstation. The radiography control device 20 may be a desktop computer, as shown in the example in Figure 1, or it may be a portable computer, such as a laptop computer or tablet computer.

[0036] The radiography control device 20 receives inspection order information from the radiography information terminal 60, etc., and transmits it to the radiography imaging system 10, thereby controlling the dynamic imaging of the radiography imaging system 10.

[0037] The examination order information includes various information related to the dynamic imaging to be performed next, such as instructions regarding respiration, patient information, examination information, imaging information, and data attributes. The examination information includes information such as the examination ID, the area to be examined (e.g., chest, especially the lungs or heart), and the type of analysis (e.g., ventilation analysis, pulmonary blood flow analysis, measurement of maximum ventilation). Examination order information is generated, for example, when a physician requests dynamic imaging of patient M from the radiographic image processing system 1.

[0038] Furthermore, the radiography control device 20 generates setting information indicating at least one of several types of dynamic analysis that the radiography image analysis device 30 can perform, based on the operator's input. When combining multiple types of dynamic analysis, the radiography control device 20 generates setting information indicating the combination of multiple types of dynamic analysis. The operator recognizes which of the multiple types of dynamic analysis to combine by, for example, referring to the contents of the examination order information, and performs an input operation to generate the setting information based on this. Alternatively, the operator may recognize which dynamic analysis to combine based on information conveyed by a physician or other person through another method.

[0039] Figure 3 is a block diagram illustrating an example of the functional configuration of the radiography control device 20 that constitutes the radiography image processing system 1. The radiography control device 20 includes a control unit 21, a storage unit 22, an operation unit 23, a display unit 24, and a communication unit 25. Each component of the radiography control device 20 is connected to the others by a bus 26.

[0040] The radiography control device 20 outputs setting conditions set by the operator and other personnel, as well as inspection order information previously acquired from the radiography information terminal 60, etc., to the radiography imaging system 10, and controls the imaging process performed by the radiography imaging system 10. The radiography control device 20 may also display the dynamic images generated by the radiography imaging system 10, for example, for the operator to review.

[0041] The control unit 21 is composed of a CPU and RAM, etc. In the control unit 21, the CPU reads system programs and various processing programs stored in the memory unit 22 in response to the operation of the operation unit 23, loads them into the RAM, and controls the operation of each part of the radiography control device 20 based on the loaded programs.

[0042] The storage unit 22 is composed of non-volatile semiconductor memory, a hard disk, or the like. The storage unit 22 stores various programs executed by the control unit 21, parameters necessary for processing by the programs, or data such as processing results (dynamic images, etc.). The various programs are stored in the form of readable program code, and the control unit 21 sequentially executes operations according to the program code.

[0043] Furthermore, the memory unit 22 stores image reading conditions for performing dynamic imaging. In addition, the memory unit 22 stores examination order information transmitted from the radiation information terminal 60, etc. When the radiation imaging control device 20 controls the dynamic imaging of the radiation imaging system 10, it reads the image reading conditions and examination order information corresponding to patient M from the memory unit 22 and transmits them.

[0044] The operation unit 23 is an operating device such as a keyboard equipped with cursor keys, number input keys, and various function keys, a pointing device such as a mouse or trackball, and a touch panel. The operation unit 23 generates instruction signals based on the operator's input and outputs them to the control unit 21.

[0045] The display unit 24 is composed of display devices such as a CRT, liquid crystal display, or organic EL display. The display unit 24 displays input instructions from the operation unit 23 and image data (such as motion images) generated by the radiation imaging system 10, in accordance with the instructions of the display signals input from the control unit 21.

[0046] The communications unit 25 transmits and receives data between the radiation image acquisition system 10, the radiation image analysis device 30, the radiation information terminal 60, etc.

[0047] [Radiation Image Analysis Device 30] The radiation image analysis device 30 is, for example, a computer such as a PC or workstation. The radiation image analysis device 30 may be a desktop computer or a portable computer, such as a laptop or tablet computer.

[0048] The radiation image analysis device 30 performs motion analysis on motion images captured by the radiation image acquisition system 10 based on the setting information set in the radiation imaging control device 20.

[0049] Figure 4 is a block diagram illustrating an example of the functional configuration of a radiation image analysis device 30 that constitutes the radiation image processing system 1. The radiation image analysis device 30 includes a control unit 31, a storage unit 32, an operation unit 33, a display unit 34, and a communication unit 35. Each component of the radiation image analysis device 30 is connected by a bus 36.

[0050] The control unit 31 is composed of a CPU and RAM, etc. In the control unit 31, the CPU reads system programs and various processing programs stored in the memory unit 32 in response to the operation of the operation unit 33, expands them into RAM, and performs operational control and dynamic analysis of each part of the radiation image analysis device 30 based on the expanded programs. As a processing program, the control unit 31 executes, for example, a radiation image processing program that performs the radiation image processing method described later.

[0051] The control unit 31 includes an image acquisition unit 311, a first processing unit 312, a second processing unit 313, and an analysis unit 314.

[0052] The image acquisition unit 311 acquires dynamic images, which are multiple frames of radiographic images generated by the radiographic image acquisition system 10 and the radiographic image acquisition control device 20.

[0053] The first processing unit 312 performs a first processing on each of the multiple frame images included in the dynamic image of the target area of ​​patient M, reducing the components of structures different from the target area of ​​patient M in the frame image.

[0054] The components of structures other than the target area are the components of structures other than the target area that overlap with the target area in terms of the direction of radiation irradiation to patient M. In this case, the first processing unit 312 may perform a recognition process to recognize parts of patient M other than the target area as components of structures other than the target area, and reduce the components of the recognized structures.

[0055] In the following explanation, we will use the component of body thickness as an example of the component of a structure different from the target area. However, the component of a structure different from the target area is not limited to the component of body thickness; it may also include, for example, the component of artificial materials.

[0056] The first processing unit 312, as a first process, extracts the body thickness component by, for example, calculating a time-direction representative value of the frame image, and subtracts the body thickness component in the frame image from the frame image. The time-direction representative value calculation process will be described in detail later, but as the body thickness component, it calculates representative values ​​for each certain range in the time direction within multiple frame images (for example, the time-direction average, median, maximum, or minimum value of the pixel values ​​of multiple frame images).

[0057] The first processing unit 312 may perform logarithmic transformation of the frame image before the first processing, which includes the calculation of time-direction representative values.

[0058] After the first processing, the second processing unit 313 performs a second processing operation in which it associates each position within the target area with other frames of images and aligns the coordinates of each associated position. Specifically, the second processing unit 313 ensures that the coordinates (x,y) of each associated position are the same across all frames of images. This process of associating each position within the target area with other frames of images and aligning the coordinates of each associated position is called registration processing.

[0059] The second processing unit 313, as a second process, for example, uses optical flow processing to track each position within the target area across multiple frame images and associate each position.

[0060] The analysis unit 314 performs motion analysis on a motion image containing multiple frame images that have undergone the first and second processing, as set in the configuration information, and obtains the analysis results. For example, the analysis unit 314 performs analysis based on signal changes in multiple frame images. In this case, if the analysis unit 314 cannot analyze the motion image (cannot obtain analysis results), it determines that analysis is not possible.

[0061] The analysis unit 314 has various types of dynamic analysis, such as blood flow analysis mode, ventilation analysis mode, adhesion analysis mode, diaphragm displacement analysis mode, and orthopedic-related measurement mode. Each mode is briefly described below.

[0062] The blood flow analysis mode visualizes signal changes within the lung field that are synchronized with the heartbeat.

[0063] The ventilation analysis mode extracts temporal signal changes in a specific time-frequency band and visualizes the behavior of lung tissue during respiration.

[0064] Adhesion analysis mode is a mode that visualizes the degree of adhesion in tissues.

[0065] The diaphragm displacement analysis mode tracks the vertical movement of the diaphragm during respiration.

[0066] The orthopedic measurement mode measures the positional changes of specified bones, such as in the limbs, and displays the trajectory of their movement.

[0067] The storage unit 32 is composed of non-volatile semiconductor memory, a hard disk, or the like. The storage unit 32 stores various programs executed by the control unit 31, parameters necessary for processing by those programs, or data such as processing results (dynamic images, analysis results, etc.). The various programs are stored in the form of readable program code, and the control unit 31 sequentially executes operations according to the program code.

[0068] Furthermore, the memory unit 32 stores patient information, examination information, and list information indicating the status (for example, progress status such as receiving, dynamic analysis in progress, analysis completed, etc.) related to each dynamic image generated by the radiographic imaging system 10. In addition, the memory unit 32 stores the analysis results associated with the dynamic images.

[0069] The operation unit 33 is an operating device such as a keyboard equipped with cursor keys, numeric input keys, and various function keys, a pointing device such as a mouse or trackball, and a touch panel. The operation unit 33 generates instruction signals based on the operator's input and outputs them to the control unit 31. The operation unit 33 may also be equipped with a touch panel on the display screen of the display unit 34, in which case it outputs instruction signals input via the touch panel to the control unit 31.

[0070] The display unit 34 is composed of display devices such as a CRT, liquid crystal display, or organic EL display. The display unit 34 displays input instructions from the operation unit 33 and image data (dynamic images, analysis results, etc.) generated by the radiation imaging system 10, in accordance with the instructions of the display signals input from the control unit 31.

[0071] The communication unit 35 transmits and receives data between the radiography control device 20 and the image management device 40, etc.

[0072] [Radiation Image Processing Methods] Figure 5 is a functional block diagram illustrating the radiation image processing method performed by the radiation image analysis device 30.

[0073] After the radiographic imaging system 10 and the radiographic imaging control device 20 capture dynamic images of the target area of ​​patient M, the image acquisition unit 311 of the control unit 31 of the radiographic image analysis device 30 acquires the dynamic images. The radiographic images consisting of multiple frames that make up the dynamic images at this stage are images before the following processing and are called true images G11 (processing B11).

[0074] The first processing unit 312 of the control unit 31 performs a logarithmic transformation on each true image G11 to obtain a logarithmic image G12 after the logarithmic transformation (processes B12 and B13). In other words, the first processing unit 312 performs a logarithmic transformation on the true image G11 to obtain a logarithmic image G12 before the time-direction representative value calculation process and optical flow processing described below. Note that the logarithmic transformation is not mandatory, and subsequent processing can be performed even with the true image G11, but performing the logarithmic transformation improves the accuracy of the processing and dynamic analysis described later.

[0075] The first processing unit 312 performs a time-direction representative value calculation process on each logarithmic image G12 and obtains a processed logarithmic image G13 (processing B14, B15). By processing the logarithmic image G12 with the time-direction representative value calculation process, a processed logarithmic image G13 can be obtained, which is an image corresponding to a component of a structure different from the target part (in this case, the body thickness component).

[0076] Here, the temporal representative value calculation process calculates representative values ​​for a certain range in the temporal direction in multiple logarithmic images G12 as the body thickness component. The temporal representative value is, for example, a value extracted from a region that has widths in both the spatial and temporal directions from the point of interest within one of the multiple logarithmic images G12. As the temporal representative value calculation process, a process can be used to calculate the median, mean, maximum, minimum, etc., of pixel values ​​in a region with arbitrary widths in the temporal and spatial directions of multiple logarithmic images G12 as representative values.

[0077] Such a time-direction representative value calculation process can be carried out using, for example, a 3D median filter. Alternatively, the process in process B14 may be any other process that performs the same processing as the time-direction representative value calculation process described above.

[0078] The processed logarithmic image G13 should ideally contain as few blood flow components as possible and as many components of structures other than the target site as possible. To remove as many blood flow components as possible, the time width of the time representative value calculation process should ideally be an integer multiple of the heart rate cycle. On the other hand, to include as many components of structures other than the target site as possible, it is desirable to minimize the time width as much as possible. Therefore, the time width of the time representative value calculation process should ideally be equivalent to one heart rate cycle. This time width corresponds to the time of a predetermined number of logarithmic images G12, including the single logarithmic image G12 of interest.

[0079] Furthermore, it is desirable to widen the spatial width of the temporal representative value calculation process to ensure that the target object is included within the region even when structures other than the target part are moving within the frame image. This allows the target object to be included within the region even when structures other than the target part are moving within the frame image, thereby reducing the gap between the representative value and the actual image value.

[0080] The first processing unit 312 obtains a body thickness reduction image G14 by subtracting the corresponding processed logarithmic image G13 from each logarithmic image G12 (processing B16, B17).

[0081] The processes B14 to B17 described above constitute the first process in the present invention, namely the body thickness reduction process.

[0082] The second processing unit 313 of the control unit 31 performs optical flow processing between logarithmic images G12 to obtain the deformation field G15 (processing B18, B19). Specifically, the second processing unit 313 performs optical flow between logarithmic images G12 adjacent in the time direction. Hereafter, images adjacent in the time direction will be referred to as adjacent images. The second processing unit 313 then calculates motion vectors by finding corresponding points between adjacent logarithmic images G12 for each small region and obtains the deformation field G15.

[0083] The second processing unit 313 performs registration processing on multiple body thickness reduction images G14 based on the deformation field G15 between adjacent logarithmic images G12 corresponding to the body thickness reduction images G14. In other words, it associates each position within the target area across multiple body thickness reduction images G14 and obtains a registration image G16 by aligning the coordinates of each associated position (processing B20, B21).

[0084] The processes B18 to B21 described above constitute the second process in the present invention.

[0085] The analysis unit 314 of the control unit 31 performs a dynamic analysis set in the configuration information, for example, a blood flow analysis mode, on the multiple registration images G16 after the second processing, and obtains an analysis result G17 that visualizes the signal changes in the lung field synchronized with the heartbeat (processing B22, B23).

[0086] Here, with reference to Figures 6 and 7, the conventional registration process and the registration process in the present invention will be explained. Figure 6 is a schematic diagram illustrating the conventional registration process. Figure 7 is a schematic diagram illustrating the registration process in the radiation image processing method shown in Figure 5.

[0087] Conventionally, when performing registration, for example, when registering the lung region, the captured frame image (frame before deformation) is deformed to match the deformation reference frame, and then alignment is performed (see the left and center figures in Figure 6). For example, in the aforementioned Patent Document 1, alignment is performed by placing the captured image in a template space containing standard shape information of the target area.

[0088] When the conventional registration described above is performed, not only the lung field being analyzed but also the thickness of the tissue before and after the lung field is deformed, and the pixel values ​​of these areas also change (see the right-hand figure in Figure 6). If the pixel values ​​of the thickness of the tissue before and after the lung field also change, the thickness component (body thickness component) will affect the dynamic analysis of the lung field, potentially leading to inaccurate analysis results.

[0089] Therefore, in the radiation image processing method according to this embodiment, before the registration process, a process is performed to remove the body thickness portion other than the lung field to be analyzed, that is, a process to remove the body thickness component from the image. For this reason, the frame image after the removal of the body thickness component (frame before deformation) is deformed to match the deformation reference frame and alignment is performed (see Figure 7). In this case, since the body thickness component has been removed, the body thickness portion before and after the lung field is not deformed, and the pixel values ​​of that portion do not change. As a result, the influence of the body thickness component on the dynamic analysis of the lung field portion is suppressed, and more accurate analysis results can be obtained.

[0090] Figure 8 shows the results of blood flow analysis obtained by performing dynamic analysis on dynamic images using a conventional registration process. Figure 9 shows the results of blood flow analysis obtained by performing dynamic analysis on dynamic images using the registration process in the radiation image processing method shown in Figure 5.

[0091] Conventionally, when performing registration of the lung region, for example, as mentioned above, the thickness component can affect the dynamic analysis of the lung region, potentially leading to inaccurate analysis results. For example, when obtaining blood flow in the lung region through dynamic analysis, even if there are areas where blood flow is actually reduced, a higher blood flow value may be obtained, and as shown in Figure 8, it may not be possible to visualize the areas with reduced blood flow in the analysis results.

[0092] In contrast, in the radiation image processing method according to this embodiment, as described above, the body thickness component is removed before the registration process, thereby suppressing the influence of the body thickness component on the dynamic analysis of the lung field. Therefore, for example, when acquiring blood flow in the lung field by dynamic analysis, if there is an area where blood flow is actually reduced, the area of ​​reduced blood flow can be visualized in the analysis results (black area in Figure 9), as shown in Figure 9, and a more accurate analysis result can be obtained. By referring to this analysis result, physicians can evaluate the condition of the lung field more accurately.

[0093] Here, we demonstrate a dynamic analysis using the blood flow analysis mode and illustrate the results obtained. However, this is not the only option; for example, a dynamic analysis using the ventilation analysis mode could be performed to obtain the ventilation state (the behavior of the lung tissue) as an analysis result.

[0094] As described above, the radiographic image analysis device 30 comprises a first processing unit 312, a second processing unit 313, and an analysis unit 314. The first processing unit 312 performs a first processing on each of the multiple frame images included in the dynamic image of the target area of ​​patient M, reducing the components of structures other than the target area in the frame image. After the first processing, the second processing unit 313 performs a second processing to associate the positions within the target area between the multiple frame images. The analysis unit 314 analyzes the radiographic dynamic image including the multiple frame images on which the first and second processing have been performed.

[0095] Thus, the first processing unit 312 performs a first processing to reduce the body thickness component of patient M in each of the multiple frame images included in the dynamic image. As a result, the second processing unit 313 can perform a second processing to associate the positions within the target area between the multiple frame images in which the influence of the body thickness component has been suppressed. In other words, the radiographic image analysis device 30 can acquire dynamic images in which the influence of the body thickness component has been suppressed. As a result, the analysis unit 314 performs dynamic analysis of the dynamic images in which the influence of the body thickness component has been suppressed, and can obtain more accurate analysis results.

[0096] This embodiment is particularly suitable for patients M who cannot hold their breath during imaging, for example, patients M admitted to the ICU (Intensive Care Unit). By performing motion imaging on patients M who are in a state of spontaneous breathing or mechanical ventilation and cannot hold their breath, and then processing the motion images as described above to perform motion analysis, it is possible to obtain analysis results such as the blood flow state and ventilation state of the patient M's lungs. Based on the obtained analysis results, a physician can diagnose and understand the condition of the patient M's lungs, for example, the possibility of pulmonary embolism and their respiratory state.

[0097] <Variation> Figure 10 is a functional block diagram illustrating a modified version of the body thickness reduction process in the radiation image processing method shown in Figure 5. The body thickness reduction process may be the one shown in Figure 10 instead of the one shown in Figure 5. The body thickness reduction process of this modified version will be described below with reference to Figure 10.

[0098] The first processing unit 312 performs a blood vessel removal process on each logarithmic image G12 to obtain a blood vessel-removed dynamic image G31 (blood vessel-removed image in the present invention) (processes B31, B32). The first processing unit 312 performs a blood vessel removal process to obtain a blood vessel-removed dynamic image G31 by, for example, extracting a portion from the lung field that has a signal change synchronized with the heartbeat, determining the extracted portion as a blood vessel, and removing the portion from the logarithmic image G12.

[0099] Furthermore, process B31 may also remove bone tissue such as the clavicle and ribs in addition to blood vessels. For example, in the logarithmic image G12, process B31 recognizes each bone tissue such as the clavicle and ribs by analyzing them using anatomical knowledge of two-dimensional X-ray imaging. Then, process B31 obtains the signal of the recognized bone tissue and removes (or attenuates) only that signal to remove the bone tissue.

[0100] The first processing unit 312 performs optical flow processing between the vascular removal dynamic images G31 to acquire a deformation field G32 (correspondence information in this invention) (processing B33, B34). Specifically, the first processing unit 312 performs optical flow between adjacent vascular removal dynamic images G31, and for each small region, it finds corresponding points between adjacent vascular removal dynamic images G31 to calculate motion vectors and acquire the deformation field G32.

[0101] The first processing unit 312 performs registration processing based on the deformation field G32 between adjacent logarithmic images G31 corresponding to the logarithmic images G12 in a plurality of logarithmic images G12. In other words, it performs correspondence between each position within the target area across the plurality of logarithmic images G12 to obtain a dynamic image G33 of the body as stationary (an image of the body as stationary in this invention) (processing B35, B36).

[0102] The first processing unit 312 performs a time averaging process to calculate a single time-averaged image G34 from the motion image G33 in which the body is stationary (processes B37, B38). The blood flow component disappears from the time-averaged image G34.

[0103] The first processing unit 312 performs inverse registration processing (process B39) by making one time-averaged image G34 follow the movement of the logarithmic image G12 (for example, by making it follow the movement of the lungs in the logarithmic image G12). This inverse registration processing acquires an inverse registration dynamic image G35 (body thickness image in the present invention) (process B40). The first processing unit 312 can, for example, perform inverse registration processing, that is, processing to associate one time-averaged image G34 with the logarithmic image G12, based on the deformation field G32 described above. This makes it possible to create an inverse registration dynamic image G35 (body thickness image) consisting of frame images that do not contain blood flow components, corresponding to each frame image of the logarithmic image G12 (for example, following the movement of the lungs in the logarithmic image G12).

[0104] The first processing unit 312 obtains a body thickness reduction image G36 by subtracting the corresponding frame image in the inverse registration dynamic image G35 (body thickness image) from each frame image of the logarithmic image G12 (processing B41, B42).

[0105] The processes B31 to B42 described above are the first process in this modified example, i.e., the body thickness reduction process, and it is possible to obtain a body thickness reduction image G36 that is equivalent to or better than the processes B14 to B17 described in the above embodiment.

[0106] Subsequently, by performing the same processing as processes B18 to B23 described in the above embodiment, the radiation image analysis device 30 can acquire dynamic images in which the influence of the body thickness component is suppressed, even in this modified example. As a result, the analysis unit 314 performs dynamic analysis of the dynamic images in which the influence of the body thickness component is suppressed, and can obtain more accurate analysis results.

[0107] The embodiments described above are merely examples of how the present invention can be implemented, and the technical scope of the present invention should not be interpreted as being limited by these embodiments. In other words, the present invention can be implemented in various forms without departing from its gist or its main features.

[0108] For example, in the above embodiment, the radiation image analysis device 30 has a first processing unit 312, but the radiation imaging control device 20 may also have a first processing unit 312. In this case, the radiation imaging control device 20 performs the first processing with the first processing unit 312, and the radiation image analysis device 30 performs the second processing with the second processing unit 313. [Explanation of symbols]

[0109] 1. Radiation Image Processing System 10. Radiation imaging system 11. Image capture control unit 12 Radiation irradiation area 13 Shooting platform 14. Radiation detection unit 15 Display section 16 Audio output section 20. Radiography control device 21 Control Unit 22 Memory section 23 Control section 24 Display section 25 Communications Department 26 bus 30. Radiation Image Analysis Device 31 Control Unit 32 Storage section 33 Operation section 34 Display section 35 Communications Department 36 bus 40 Image management device 50 client terminals 60 Radiation Information Terminal 111 Configuration Information Acquisition Unit 112 Shooting Condition Determination Unit 113 Image generation unit 114 Storage section 311 Image acquisition unit 312 First Processing Unit 313 Second Processing Unit 314 Analysis Department

Claims

1. A first processing unit performs a first processing operation on each of several frame images included in the radiodynamic image of the target area of ​​the subject, which reduces the component of a structure different from the target area in the frame image. A second processing unit performs a second processing operation to associate the positions within the target area between the plurality of frame images, An analysis unit that analyzes the radiodynamic image, which includes a plurality of frame images that have undergone the first and second processing, Equipped with, Radiation image analysis device.

2. The second processing unit performs a registration process to align the coordinates of the associated positions with the plurality of frame images that have undergone the second processing. The radiation image analysis apparatus according to claim 1.

3. The analysis unit performs analysis based on signal changes in multiple frame images included in the radiodynamic image. The radiation image analysis apparatus according to claim 1.

4. The analysis unit performs an analysis of the blood flow of the subject. The radiation image analysis apparatus according to claim 1.

5. The aforementioned target area is the lung field. The analysis unit performs processing to analyze the blood flow in the lung field. The radiation image analysis apparatus according to claim 1.

6. The aforementioned target area is the lung field. The analysis unit performs processing to analyze the ventilation state of the lung field. The radiation image analysis apparatus according to claim 1.

7. The first processing unit, as a first process, subtracts from the frame image components of structures different from the target part in the frame image. The radiation image analysis apparatus according to claim 1.

8. The components of the aforementioned structure are those of the structure located in a position that overlaps with the target area in terms of the direction of radiation irradiation to the subject. The radiation image analysis apparatus according to claim 1.

9. The first processing unit performs a recognition process to recognize parts of the subject other than the target part as components of the structure, and reduces the recognized components of the structure. The radiation image analysis apparatus according to claim 1.

10. The first processing unit subtracts a representative value in the time direction from the plurality of frame images. The radiation image analysis apparatus according to claim 1.

11. The aforementioned representative value in the time direction is the time-direction mean, median, maximum, or minimum value of the pixel values ​​of the plurality of frame images. The radiation image analysis apparatus according to claim 10.

12. The first processing unit subtracts representative values ​​for each certain time range within the plurality of frame images. The radiation image analysis apparatus according to claim 1.

13. The aforementioned representative value is a value extracted from within a region having spatial and temporal widths, respectively, from the point of interest within one of the multiple frame images. The aforementioned width in the time direction is the time corresponding to a predetermined number of frame images, including the one frame image. The radiation image analysis apparatus according to claim 12.

14. The aforementioned time-direction width is the time equivalent to one heartbeat cycle. The radiation image analysis apparatus according to claim 13.

15. The representative values ​​for each certain range in the time direction are the mean, median, maximum, or minimum values ​​in the time direction. The radiation image analysis apparatus according to claim 14.

16. The first processing unit performs logarithmic transformation of the frame image before the first processing. The radiation image analysis apparatus according to claim 1.

17. The first processing unit is, A process to remove blood vessels from the lung field of the subject in the frame image to obtain a blood vessel-removed image, The process involves tracking the position within the target area across multiple images of blood vessel removal and acquiring correspondence information to associate that position, and then, based on the correspondence information, performing position matching across the multiple frame images to obtain an image of the body standing still. The process of calculating a time-averaged image from the aforementioned images of a stationary body, A reverse registration process is performed to associate the time-averaged image with the multiple frame images and to create a body thickness image corresponding to the multiple frame images. A process to obtain a thickness-reduced image by subtracting the thickness image corresponding to the frame image from the frame image, To do The radiation image analysis apparatus according to claim 7.

18. The second processing unit, as the second process, tracks the position within the target area across the plurality of frame images and associates the positions. The radiation image analysis apparatus according to claim 1.

19. The second processing unit performs positional mapping within the target area by optical flow processing. The radiation image analysis apparatus according to claim 18.

20. In a radiation image analysis device, For each of the multiple frame images included in the radiodynamic image of the target area of ​​the subject, a first process is performed to reduce the components of structures different from the target area in the frame image. A second process is performed to associate the positions within the target area between the multiple frame images. The radiodynamic image, which includes a plurality of frame images that have undergone the first and second processing, is analyzed. Radiation image processing method.

21. In the computer of the radiation image analysis device, A first process is performed on each of the multiple frame images included in the radiodynamic image of the target area of ​​the subject, which reduces the component of structures different from the target area in the frame image. A second process is performed to associate the positions within the target area between the plurality of frame images, Analysis process for analyzing the radiodynamic image, which includes a plurality of frame images that have undergone the first and second processes, To execute A program for processing radiation images.

Images