Radiographic imaging device for obtaining improved radiographic images and method of operating the radiographic imaging device

Abstract

The radiation imaging apparatus of the present disclosure includes an image output unit that outputs a first radiation image included in a series of radiation images acquired by radiation imaging of a subject, an image brightness information extraction unit that acquires brightness information from the first radiation image, a first irradiation condition calculation unit that determines a first irradiation condition based on the brightness information, an irradiation control unit that controls the dose of radiation based on the first irradiation condition, a second irradiation condition calculation unit that determines a second irradiation condition based on a second radiation image generated based on the first irradiation condition when the imaging site of the subject is fixed, and a dose reduction unit that reduces or maintains the dose of radiation based on the second irradiation condition.

Description

[Technical Field]

[0001] TECHNICAL FIELD The present disclosure relates to a radiographic imaging device for acquiring improved radiographic images and a method of operating the radiographic imaging device. BACKGROUND When acquiring successive radiographic images, the radiographic imaging device determines irradiation conditions using different methods. [Background technology]

[0002] Low-dose radiation imaging devices are becoming increasingly important in medical imaging because they reduce the risk of side effects. Such devices can achieve low doses by using advanced software algorithms, improved hardware components, and new types of radiation sources.

[0003] Radiographic imaging devices that achieve low doses are limited in that they may produce images with reduced contrast and spatial resolution, which may make it more difficult to detect small lesions or abnormalities. Low-dose imaging may also be incompatible with certain types of imaging procedures that require high-dose imaging to visualize specific structures or abnormalities.

[0004] Additionally, low-dose radiography equipment can be relatively expensive, which can limit accessibility, and implementing new technologies and techniques can require additional education and expertise from radiologists and radiologists, making adoption of low-dose imaging equipment difficult.

[0005]

[0003] As a type of low-dose radiation imaging device, a radiation imaging device is widely known as equipment used during surgery and treatment by continuously irradiating X-rays onto a target area of ​​a human or animal body to obtain a fluoroscopic image of the target area in real time. When performing surgery on a patient using a radiation imaging device, there is a problem in that the irradiation conditions and image brightness cannot be maintained at a constant level because they are affected by objects other than the target of interest, such as the surgeon's hands and surgical tools. Furthermore, existing automatic irradiation condition adjustment methods use irradiation conditions that can be used for various subjects, so that a radiation dose greater than the appropriate dose for the actual subject being imaged may be irradiated.

[0006] Despite these limitations, there is a demand for using low-dose radiation imaging devices in medical imaging because minimizing radiation exposure can reduce the risk of side effects and improve patient safety. Accordingly, various studies are being conducted to realize low-dose radiation imaging devices. Summary of the Invention [Problem to be solved by the invention]

[0007] The present disclosure provides a radiation imaging device that can quickly obtain low-dose radiation images, minimizing the burden on patients and users. [Means for solving the problem]

[0008] The radiation image capturing device according to the present disclosure includes an image output unit that outputs a first radiation image included in successive radiation images acquired by radiation capturing of a subject, an image brightness information extraction unit that acquires brightness information from the first radiation image, a first irradiation condition calculation unit that determines first irradiation conditions based on the brightness information, an irradiation control unit that controls the radiation dose based on the first irradiation conditions, a second irradiation condition calculation unit that determines second irradiation conditions based on second radiation images generated based on the first irradiation conditions when the imaging region of the subject is fixed, and a dose reduction unit that reduces or maintains the radiation dose based on the second irradiation conditions.

[0009] The value obtained by subtracting the radiation dose based on the second irradiation condition from the radiation dose based on the first irradiation condition of the radiographic imaging device according to the present disclosure is equal to or smaller than 70% of the dose based on the first irradiation condition.

[0010] The radiographic image capturing apparatus according to the present disclosure deactivates the first irradiation condition calculation unit when the dose is reduced by the dose reducing unit.

[0011] The radiation image capturing device according to the present disclosure generates an improved current frame image by accumulating and averaging pixel values ​​included in a current frame image included in a third radiation image output using a reduced dose by a dose reduction unit and a previous frame image included in the third radiation image.

[0012] The radiographic imaging device according to the present disclosure further includes an image post-processing unit that performs post-processing on the third radiographic image output at the reduced dose by the dose reduction unit, and the image post-processing unit adjusts at least one of the brightness information and the contrast information of the third radiographic image to be similar to at least one of the brightness information and the contrast information of the second radiographic image.

[0013] A radiographic imaging device according to the present disclosure includes a radiation irradiation unit that irradiates radiation onto a subject, an image acquisition unit that receives radiation irradiated from the radiation irradiation unit and passed through the subject to generate successive radiographic images, and a control unit that controls the radiation irradiation unit and the image acquisition unit. A method for operating the radiographic imaging device includes the steps of: acquiring brightness information based on first radiographic images included in the successive radiographic images; determining first irradiation conditions based on the brightness information using a first algorithm; controlling the radiation dose based on the first irradiation conditions; acquiring second radiographic images included in the successive radiographic images and generated based on the first irradiation conditions; acquiring motion presence / absence information indicating whether the imaging region of the subject has been fixed; determining second irradiation conditions based on the second radiographic images using a second algorithm if the motion presence / absence information indicates that the imaging region of the subject has been fixed; controlling the radiation dose based on the second irradiation conditions; and acquiring third radiographic images included in the successive radiographic images and generated based on the second irradiation conditions.

[0014] In the method for operating a radiographic imaging device according to the present disclosure, the radiation dose based on the second irradiation condition is equal to or greater than 30% of the radiation dose based on the first irradiation condition.

[0015] In the method for operating a radiographic imaging device according to the present disclosure, the first algorithm for determining the first irradiation condition and the second algorithm for determining the second irradiation condition are different from each other.

[0016] The step of acquiring a third radiographic image in the method of operating a radiographic imaging device according to the present disclosure includes a step of generating an improved current frame image by accumulating and averaging pixel values ​​included in at least a portion of a current frame image included in the third radiographic image and pixel values ​​included in at least a portion of a previous frame image included in the third radiographic image.

[0017] The step of acquiring a third radiation image in the method of operating a radiation image capturing device according to the present disclosure includes the steps of: generating a motion detection image including motion detection information for each pixel of a difference image obtained by subtracting a current frame image included in the third radiation image from a previous frame image included in the third radiation image; generating a motion probability image based on the generated motion detection image and motion detection images accumulated up to the previous frame; and generating an improved current frame image by blending the current frame image and the previous frame image based on the motion probability image.

[0018] The step of generating a motion probability image in the operating method of the radiographic imaging device according to the present disclosure includes a step of generating a motion probability image by combining one or more of the motion detection image of the current frame and the motion detection images up to the previous frame, and the step of generating an improved current frame image includes a step of variably determining a mixing ratio of the current frame image and the previous frame image according to a value indicating the degree of motion of each pixel of the motion probability image, and the mixing ratio is determined so that the greater the degree of motion indicated by the value of each pixel of the motion probability image, the greater the reflection ratio of the current frame image compared to the previous frame image.

[0019] In the method for operating a radiographic imaging device according to the present disclosure, the step of acquiring brightness information includes a step of acquiring the brightness information by averaging pixel values ​​included in at least a portion of the first radiographic image, and the step of determining first irradiation conditions includes a step of determining first irradiation conditions such that the brightness information is increased when the brightness information is smaller than predetermined first critical brightness information, and a step of determining first irradiation conditions such that the brightness information is decreased when the brightness information is larger than the predetermined first critical brightness information.

[0020] In the method for operating a radiographic imaging device according to the present disclosure, the step of acquiring brightness information by averaging pixel values ​​included in at least a portion of a first radiographic image includes the steps of acquiring an area in which the subject appears from the first radiographic image based on an object area acquisition model, and acquiring brightness information by averaging pixel values ​​included in the area in which the subject appears.

[0021] The step of determining the second irradiation conditions in the method of operating the radiographic imaging device according to the present disclosure includes the steps of downsampling the second radiographic image in units of patches of a predetermined size to obtain a downsampled image, obtaining a minimum pixel value from among pixel values ​​included in the downsampled image, and, if the minimum pixel value is greater than predetermined second critical brightness information, determining the second irradiation conditions so that the minimum pixel value is equal to the second critical brightness information.

[0022] In the method for operating a radiographic imaging device according to the present disclosure, the step of determining second irradiation conditions so that the minimum pixel value is equal to the second critical brightness information includes the steps of determining a reduction rate based on the minimum pixel value and the second critical brightness information, and determining second irradiation conditions so that the radiation irradiation unit irradiates a dose obtained by subtracting the dose under the first irradiation conditions multiplied by the reduction rate from the dose under the first irradiation conditions, wherein the reduction rate is greater than 0 and less than a predetermined maximum reduction rate.

[0023] The step of acquiring the motion presence / absence information in the operating method of the radiographic imaging device according to the present disclosure includes a step of determining the motion presence / absence information to indicate that the imaging region of the subject is not fixed, if the time period during which at least one of the first radiographic image and the second radiographic image is acquired is less than a predetermined critical time, and a step of determining the motion presence / absence information to indicate that the imaging region of the subject is fixed, if the time period during which at least one of the first radiographic image and the second radiographic image is acquired is equal to or greater than the predetermined critical time.

[0024] In addition, a program for implementing the above-described method of operating the radiation image capturing apparatus may be recorded on a computer-readable recording medium. [Effects of the Invention]

[0025] The radiographic imaging device of the present disclosure can explicitly fix image brightness to solve the above-mentioned problems, and when the radiographic imaging device determines that the imaging region is fixed, it can reduce the radiation exposure of the patient by using irradiation conditions optimized for the region.

[0026] The radiation imaging device of the present disclosure can minimize radiation exposure for patients and users by acquiring low-dose radiation images. The radiation imaging device of the present disclosure can also provide users with high-sharpness images at low doses, thereby assisting users in making medical decisions. The radiation imaging device of the present disclosure can also minimize image processing, thereby quickly acquiring low-dose radiation images, thereby helping users perform medical procedures more quickly. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a diagram illustrating a mobile radiographic imaging device according to an embodiment of the present disclosure. [Figure 2] 1 is a block diagram showing various configurations that may be included in a radiographic image capturing apparatus according to an embodiment of the present disclosure; [Figure 3] 10 is a flowchart illustrating an operation method of a radiation image capturing apparatus according to an embodiment of the present disclosure. [Figure 4] 10 is a flowchart illustrating an operation method of a radiation image capturing apparatus according to an embodiment of the present disclosure. [Figure 5] 10 is a flowchart illustrating the operation of a radiographic image capturing apparatus according to an embodiment of the present disclosure. [Figure 6] FIG. 10 is a diagram illustrating downsampling according to an embodiment of the present disclosure. [Figure 7] 10 is a flowchart illustrating a process for obtaining a second irradiation condition according to an embodiment of the present disclosure. [Figure 8] FIG. 2 is a diagram for explaining the operation of the radiation image capturing device according to an embodiment of the present disclosure. [Figure 9]10 is a flowchart illustrating the operation of a radiographic image capturing apparatus according to an embodiment of the present disclosure. [Figure 10] FIG. 2 is a diagram for explaining the operation of the radiation image capturing device according to an embodiment of the present disclosure. [Figure 11] FIG. 2 is a diagram for explaining the operation of the radiation image capturing device according to an embodiment of the present disclosure. [Figure 12] FIG. 2 is a diagram for explaining the operation of the radiation image capturing device according to an embodiment of the present disclosure. BEST MODE FOR CARRYING OUT THE INVENTION

[0028] The advantages and features of the disclosed embodiments, and methods for achieving them, will become apparent from the following detailed description of the embodiments taken in conjunction with the accompanying drawings. However, the present disclosure may be embodied in various different forms and is not limited to the following embodiments. The following embodiments are provided solely for the purpose of completeness and completeness of the disclosure, and to fully convey the scope of the invention to those skilled in the art.

[0029] The terms used in this specification will be briefly explained, and the disclosed embodiments will be specifically explained.

[0030] The terms used in this specification have been selected from currently widely used general terms while taking into consideration the function of the present disclosure, but these may change depending on the intentions of engineers in the relevant field, precedents, the emergence of new technologies, etc. In addition, in certain cases, terms may be arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the relevant description of the invention. Therefore, the terms used in this disclosure should be defined based on the meanings of the terms and the overall content of the present disclosure, rather than simply by the names of the terms.

[0031] In this specification, the singular expression includes the plural expression unless the context clearly dictates otherwise, and the plural expression includes the singular expression unless the context clearly dictates otherwise.

[0032] When a part of the entire specification is described as "comprising" a certain element, this means that it may further include other elements, but not excluding other elements, unless specifically stated to the contrary.

[0033] Additionally, the term "module" as used herein refers to a software or hardware component that performs a specific function. However, the term "module" is not limited to software or hardware. A "module" may be configured to reside on an addressable storage medium or to execute on one or more processors. Thus, by way of example, "module" includes components such as software components, object-oriented software components, class components, and task components, as well as processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided within components and "modules" may be combined into fewer components and "modules" or further separated into additional components and "modules."

[0034] According to one embodiment of the present disclosure, a "unit" may be embodied with a processor and memory. The term "processor" should be broadly interpreted to include a general-purpose processor, a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a controller, a microcontroller, a state machine, etc. In some environments, a "processor" may refer to an application specific integrated circuit (ASIC), a programmable logic device (PLD), a field programmable gate array (FPGA), etc. The term "processor" may also refer to a combination of processing devices, such as, for example, a combination of a DSP and a microprocessor, a combination of multiple microprocessors, a combination of one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0035] The term "memory" should be interpreted broadly to include any electronic component capable of storing electronic information. The term "memory" may refer to various types of processor-readable media, such as random access memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable PROM (EEPROM), flash memory, magnetic or optical data storage devices, registers, etc. Memory is said to be in electronic communication with a processor when the processor can read information from or store information in the memory. Memory that is integrated into a processor is in electronic communication with the processor.

[0036] Hereinafter, the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present disclosure. In order to clearly explain the present disclosure, the drawings will be omitted to avoid the need for explanation.

[0037] FIG. 1 is a diagram showing a mobile radiographic imaging device according to an embodiment of the present disclosure.

[0038] 1 illustrates an example of a C-arm type radiographic imaging device 100 according to an embodiment of the present disclosure. However, the present disclosure is not limited to this, and the radiographic imaging device 100 of the present disclosure may have various forms.

[0039] A radiographic imaging device according to an embodiment of the present disclosure can acquire video images by being configured in a C-arm form as shown in Fig. 1. The radiographic imaging device can capture an image of a region of interest of a subject S, which is an imaging target, using radiation such as X-rays.

[0040] 1, the radiographic imaging device 100 may include a radiation irradiator 111 that outputs radiation, for example, X-rays, and an image acquirer 112 that receives the radiation that has passed through a subject S and acquires image data, and the radiation irradiator 111 and the image acquirer 112 may be supported on both ends of a C-arm 110. For example, the radiographic imaging device may be applied to a mobile C-arm X-ray imaging device, an interventional X-ray device, an interventional angiography C-arm X-ray device, etc.

[0041] The support structure supports the radiation emitting unit 111 and the image acquiring unit 112 and is configured to change the spatial and rotational positions of the radiation emitting unit 111 and the image acquiring unit 112 in order to change the imaging position and angle of the subject S. For example, the support structure may include a support body 150, a lift column 130 fastened to the support body 150 so as to be movable in a vertical direction D1, and a forward / backward moving arm 120 fastened to the lift column 130 so as to be movable in a vertical direction D2 relative to the lift column 130.

[0042] The C-arm 110 is fastened to the forward / backward movement arm 120 so as to be rotatable relative to the forward / backward movement arm 120 in at least one rotational direction, and the radiation irradiation unit 111 and the image acquisition unit 112 are fastened to both ends of the C-arm 110. In this case, the C-arm 110 can move up and down together with the forward / backward movement arm 120 and move forward and backward horizontally, and can also be fastened to the forward / backward movement arm 120 so as to be rotatable relative to the forward / backward movement arm 120 in at least one rotational direction, for example, an orbital rotation direction R1 and an axial rotation direction R2 centered on a direction parallel to the horizontal movement direction of the forward / backward movement arm 120. Although not shown in the drawings, the support structure may include an actuator such as a motor for vertical movement of the lift column 130, horizontal movement of the forward / backward movement arm 120, and rotation of the C-arm 110. The elements for supporting and driving the C-arm 110, which is a support member supporting the radiation irradiation unit 111 and the image acquisition unit 112, i.e., the forward / backward movement arm 120, the lift column 130, and the actuators provided thereon, can be said to be driving elements for driving the C-arm 110, and a combination of these can be said to be a driving unit for driving the C-arm 110. In addition, the forward / backward movement arm 120 may be configured to enable panning rotation of the C-arm 110 through lateral rotation. The shape of the support member is not limited to a C-shape, and in other embodiments of the present disclosure, arms shaped like U-shapes, G-shapes, O-shapes, etc. may be used as the support member instead of the C-shape.

[0043] The display unit 140 is configured to display at least one of real-time position information, image data, reference position information, and radiation output information. The display unit 140 may be any device capable of displaying information and images, such as a printer, a CRT display, an LCD display, a PDP display, an OLED display, an FED display, an LED display, a DLP display, a PFD display, a 3D display, a transparent display, etc. The display unit 140 may also be implemented in a form capable of displaying and inputting information, such as a touch screen that can receive input from a user.

[0044] FIG. 2 is a block diagram showing various components that may be included in a radiographic imaging device according to an embodiment of the present disclosure.

[0045] 2, the radiation imaging apparatus 100 may include at least one of a control unit 200, a sensor unit 210, a communication unit 220, a memory 230, an output unit 240, and an input unit 250. While FIG. 1 schematically illustrates the exterior of the radiation imaging apparatus 100, FIG. 2 illustrates a functionally separated block diagram of the radiation imaging apparatus 100. At least one of the control unit 200, the sensor unit 210, the communication unit 220, the memory 230, the output unit 240, and the input unit 250 in FIG. 2 may be included inside at least one of the radiation irradiation unit 111, the image acquisition unit 112, the support body 150, the lift column 130, and the forward / backward movement arm 120 in FIG. 1, or may be coupled to the outside of at least one of the radiation irradiation unit 111, the image acquisition unit 112, the support body 150, the lift column 130, and the forward / backward movement arm 120.

[0046] The radiographic imaging apparatus 100 according to the embodiment of the present disclosure may include a control unit 200. The control unit 200 may be embodied in the form of an information processing device, such as one or more computers, capable of information processing and calculation. For example, the computer may include a control unit such as a CPU, a storage unit such as a ROM (read only memory) or a RAM (random access memory), and a graphics control unit such as a GPU (graphics processing unit). The computer may also include a communication unit such as a network card, and input / output units such as a keyboard, a display, or a touch screen. These computer components may be connected via a bus as known in the art and may be operated and controlled by executing a program stored in the storage unit.

[0047] The radiographic imaging device 100, which may be embodied in the form of a computer capable of information processing, may be installed in the radiographic imaging device 100 shown in FIG. 1 and configured to perform image processing functions. In this case, the radiographic imaging device may be configured to receive and process images captured as part of the radiographic imaging device, and the processed images may be displayed on the display unit 140 of the radiographic imaging device.

[0048] The radiation imaging device 100 may include a sensor unit 210. The sensor unit 210 may acquire various information using at least one sensor. The sensor unit 210 may be a sensor using a measuring means such as pressure, potential, or optics. For example, the sensor unit 210 may include at least one of a distance measuring sensor or an encoder. The sensor may also include a pressure sensor, an infrared sensor, an LED sensor, a touch sensor, etc., but is not limited thereto. The sensor unit may be included in at least one of the radiation emitting unit 111, the image acquiring unit 112, the support body 150, the lift column 130, the forward / backward moving arm 120, and the C-arm 110.

[0049] The radiographic imaging apparatus 100 may also include a communication unit 220. The communication unit 220 may be configured to enable the radiographic imaging apparatus 100 to communicate with an internal module or an external device via wired or wireless communication. The external device may include an external server or a user terminal. The user terminal may include a PC, a smartphone, a tablet, or a wearable device. The communication unit 220 may include a wired / wireless communication module for network connection. Examples of wireless communication technologies include Wireless LAN (WLAN) (Wi-Fi), Wireless Broadband (Wibro), World Interoperability for Microwave Access (Wimax), and High Speed ​​Downlink Packet Access (HSDPA). Examples of wired communication technologies include Digital Subscriber Line (XDSL), Fibers to the Home (FTTH), and Power Line Communication (PLC). The network connection unit may also include a short-range communication module to transmit and receive data to and from any device / terminal located in a short distance. For example, short range communication technologies that may be used include, but are not limited to, Bluetooth (registered trademark), RFID (Radio Frequency Identification), Infrared Data Association (IrDA), UWB (Ultra-Wideband), and ZigBee.

[0050] The radiation imaging apparatus 100 may include a memory 230. The control unit 200 may execute commands stored in the memory. The control unit 200 and the memory 230 may be, but are not limited to, independent hardware. The control unit 200 may include the memory 230. That is, the memory 230 may be included in the control unit 200 or may be external to the control unit 200. The memory 230 may store various information related to the radiation imaging apparatus 100. For example, the memory 230 may include information related to an operation method of the radiation irradiation unit 111, and may include, but is not limited to, captured images and user authentication information.

[0051] The memory 230 may be implemented as a non-volatile storage medium capable of persistently storing any data. For example, the memory 230 may include, but is not limited to, a disk, optical disk, magneto-optical storage device, flash memory, and / or battery-backed memory-based storage device. The memory 230 may refer to, but is not limited to, a primary storage device directly accessed by the processor, such as random access memory (RAM), including dynamic random access memory (DRAM) and static random access memory (SRAM), and a volatile storage device in which stored information is instantly erased when power is turned off. The memory 230 may be operated by the control unit 200. The control unit 200 may also execute commands stored in the memory 230.

[0052] Furthermore, the radiation image capturing apparatus 100 may further include an operation unit that provides an interface for operating the radiation image capturing apparatus 100. The operation unit may include an output unit 240 and an input unit 250.

[0053] The output unit 240 may output, under the control of the control unit 200, sound and images indicating imaging-related information such as X-ray irradiation or enabling confirmation of the status of the main body. The output unit 240 may include the display unit 140. The output unit 240 may include a speaker or a display. The output unit 240 may output medical images generated by the control unit 200. The output unit 240 may output information necessary for a user to operate the radiographic imaging device 100, such as a user interface (UI), user information, or subject information. Examples of the output unit 240 may include a speaker, a printer, a CRT display, an LCD display, a PDP display, an OLED display, an FED display, an LED display, a VFD display, a DLP display, an FPD display, a 3D display, a transparent display, etc., and may include various other output devices within the scope obvious to those skilled in the art.

[0054] The radiographic image capturing apparatus 100 may be connected to a workstation via wired or wireless communication. The workstation may be located in a space physically separated from the radiographic image capturing apparatus 100.

[0055] The workstation may include a storage server. The storage server may store medical images, information about the subject, information about the user (medical professional), etc. The workstation may include a review device. The review device may receive medical images from the storage server based on a user's command and diagnose the medical images. The workstation and the radiation image capturing device 100 may transmit, store, process, and output data in accordance with the DICOM (Digital Imaging and Communications in Medicine) standard. The workstation may also include a PACS (Picture Archiving and Communication System).

[0056] The workstation may include an output unit, an input unit, and a control unit. The output unit and the input unit provide a user with an interface for operating the workstation and the radiation image capturing apparatus 100. The control unit of the workstation may control the workstation and the radiation image capturing apparatus 100.

[0057] The radiographic imaging apparatus 100 can be controlled through a workstation, and can also be controlled by a control unit 200 included in the radiographic imaging apparatus 100. Therefore, a user can control the radiographic imaging apparatus 100 through a workstation, or can control the radiographic imaging apparatus 100 through an operation unit and the control unit 200 included in the radiographic imaging apparatus 100. In other words, a user can remotely control the radiographic imaging apparatus 100 through a workstation, or can directly control the radiographic imaging apparatus 100.

[0058] The control unit of the workstation and the control unit 200 of the radiographic imaging device 100 may be separate, but are not limited to this. The control unit of the workstation and the control unit 200 of the radiographic imaging device 100 may be embodied as a single integrated control unit, or the integrated control unit may be included in only one of the workstation and the radiographic imaging device 100. Hereinafter, the control unit 200 may refer to the control unit of the workstation and / or the control unit of the radiographic imaging device 100.

[0059] The output unit and input unit of the workstation and the output unit 240 and input unit 250 of the radiation imaging device 100 may provide a user with an interface for operating the radiation imaging device 100. The workstation and the radiation imaging device 100 may each include an output unit and an input unit, but are not limited thereto. The output unit or the input unit may be implemented in only one of the workstation and the radiation imaging device 100.

[0060] Hereinafter, the input unit 250 refers to the input unit of the workstation and / or the input unit of the radiation image capturing device 100, and the output unit 240 refers to the output unit of the workstation and / or the output unit of the radiation image capturing device 100.

[0061] The input unit 250 may receive inputs from a user of commands for operating the radiographic imaging apparatus 100 and various information related to X-ray imaging. The control unit 200 may control or operate the radiographic imaging apparatus 100 based on the information input to the input unit 250. The input unit 250 may include a joystick, a keyboard, a mouse, a touch screen, a shooting button, an unlocking button, a voice recognizer, a fingerprint recognizer, an iris recognizer, a human body motion recognizer, etc., and may also include other input devices obvious to those skilled in the art.

[0062] A user can input a command for X-ray irradiation through the input unit 250, and a switch for inputting such a command may be provided on the input unit 250. The switch may be provided so that an irradiation command for X-ray irradiation is input when pressed at least once.

[0063] For example, when a user presses a switch, the switch inputs a preparation command instructing preheating for X-ray irradiation, and when the switch is pressed further in this state, an irradiation command for actual X-ray irradiation is input. In this manner, when a user operates the switch, the control unit 200 generates a signal corresponding to the command input through the switch operation, i.e., a preparation signal, and transmits the signal to a high voltage generator that generates a high voltage for generating X-rays. The high voltage generator may be included in the radiation irradiation unit 111.

[0064] The high voltage generator included in the radiation irradiation unit 111 receives a preparation signal from the control unit 200 to start preheating, and when preheating is complete, transmits a preparation completion signal to the control unit 200. In order to detect X-rays, the image acquisition unit 112 also needs to prepare for X-ray detection, and the control unit 200 transmits a preparation signal to the image acquisition unit 112 so that the image acquisition unit 112 can prepare to detect X-rays that have passed through the subject, as well as preheating the high voltage generator. When the image acquisition unit 112 receives the preparation signal, it prepares to detect X-rays, and when detection preparation is complete, transmits a detection preparation completion signal to the control unit 200.

[0065] When the preheating of the high voltage generator included in the radiation irradiator 111 is completed and the image acquirer 112 is ready to detect X-rays, the controller 200 transmits an irradiation signal to the high voltage generator, and the high voltage generator generates a high voltage and applies it to the X-ray source included in the radiation irradiator 111, causing the X-ray source to irradiate X-rays. The X-ray source can vary the X-ray irradiation dose depending on at least one of the tube voltage, tube current, and X-ray pulse irradiation time controlled by the controller 200.

[0066] When transmitting the irradiation signal, the control unit 300 may transmit a sound or light output signal to the output unit 240 so that the output unit 240 outputs a predetermined sound or light so that the subject or the user can be notified of the X-ray irradiation. The output unit 240 may also output a sound or light indicating other imaging-related information in addition to the X-ray irradiation. The output unit 240 may be included in the operation unit, but is not limited thereto. The output unit 240 or a part of the output unit 240 may be located at a location different from the location where the operation unit is located. For example, it may be located on a wall of an imaging room where X-ray imaging of the subject is performed.

[0067] The control unit 200 controls the positions of the radiation irradiating unit 111 and the image acquiring unit 112, the timing and conditions for imaging, etc., according to imaging conditions set by the user.

[0068] Specifically, the control unit 200 controls the high voltage generator and the image acquiring unit 112 according to commands input through the input unit 250, thereby controlling the timing of X-ray irradiation, the intensity of X-rays, the area of ​​X-ray irradiation, etc. The control unit 200 also adjusts the position of the image acquiring unit 112 according to predetermined imaging conditions, and controls the operation timing of the image acquiring unit 112.

[0069] The control unit 200 also generates a medical image of the subject using image data received through the image acquisition unit 112. Specifically, the control unit 200 receives image data from the image acquisition unit 112, removes noise from the image data, and adjusts a dynamic range and interleaving to generate a medical image of the subject.

[0070] The workstation may further include a communication unit (not shown) that can be connected to a server, a medical device, a portable terminal, etc. via a network. The workstation may be one of the external devices.

[0071] The control unit 200 according to an embodiment of the present disclosure will be described in more detail below. The control unit 200 may include at least one hardware module or at least one software module. Here, a module may refer to at least one of hardware or software divided into functional units. More specifically, the control unit 200 of the radiographic imaging device 100 may include at least one of an image output unit 201, an image brightness information extraction unit 202, a first irradiation condition calculation unit 203, an irradiation control unit 204, a second irradiation condition calculation unit 205, and a dose reduction unit 206.

[0072] The image output unit 201 may be configured to output a first radiation image included in a series of radiation images acquired by radiographing a subject. The image output unit 201 may be included in the control unit 200 and configured to process data acquired from the image acquisition unit 112 to generate a series of radiation images. However, the present invention is not limited thereto, and the image output unit 201 may be included in the output unit 240 and configured to display images generated by the control unit 200. The series of radiation images may be called, for example, at least one of X-ray video, X-ray motion imaging, and fluoroscopy.

[0073] The radiographic imaging device 100 can capture a series of radiographic images. That is, the radiographic imaging device 100 can capture a moving image. The series of radiographic images can include a plurality of still radiographic images. In the present disclosure, a still radiographic image can be referred to as a frame image.

[0074] The first radiographic image may be included in a series of radiographic images. The first radiographic image may include at least one frame image. The first radiographic image may be an image acquired by image processing at least one frame image. The radiographic image capturing device 100 may store predetermined irradiation conditions. The predetermined irradiation conditions may include at least one of a predetermined tube voltage, a predetermined tube current, and a predetermined X-ray pulse irradiation time. The predetermined irradiation conditions may be stored in the radiographic image capturing device 100 or may be automatically selected at the time of capturing. Alternatively, the predetermined irradiation conditions may be selected by the user. The radiographic image capturing device 100 controls the radiation emitting unit 111 to irradiate the subject with radiation based on the predetermined irradiation conditions, and the image acquiring unit 112 can acquire the first radiographic image.

[0075] The first radiographic image may include an image of the subject. In order for the subject to appear clearly in the radiographic image, it may be necessary to change the irradiation conditions according to the subject information. However, since the first radiographic image uses predetermined irradiation conditions, it may not be an image optimized according to the subject information. Here, the subject information may include at least one of the subject's thickness, the subject's type, the subject's location, the subject's material, and the subject's density. Therefore, the radiographic image capturing device 100 may further include the following components to implement a low radiation dose and determine optimized irradiation conditions for the subject.

[0076] The image brightness information extracting unit 202 may include a step of acquiring brightness information from the first radiation image. The image brightness information extracting unit 202 may be included in the control unit 200.

[0077] The region of interest may be extracted automatically without user intervention. The image brightness information extraction unit 202 may acquire brightness information based on at least one of statistical values ​​such as maximum value, minimum value, average value, median value, and standard deviation of pixels, distribution of pixel values ​​(e.g., histogram), feature points extracted from the image, and feature point locations. The process by which the image brightness information extraction unit 202 acquires brightness information will be described later.

[0078] The first irradiation condition calculation unit 203 can determine the first irradiation condition based on the brightness information. The first irradiation condition calculation unit 203 can also be included in the control unit 200. The first irradiation condition calculation unit 203 may be configured to control the brightness information of the first radiographic image so that it resembles predetermined brightness information. The first irradiation condition may be information for controlling the radiation irradiator 111. The first irradiation condition may include at least one of a first tube voltage, a first tube current, and an irradiation time of the first X-ray pulse.

[0079] The first irradiation condition calculation unit 203 may determine at least one of the first tube voltage, the first tube current, and the irradiation time of the first X-ray pulse of the radiation irradiator 111 based on the brightness information of the first radiographic image. For example, the X-ray irradiation dose may increase as at least one of the first tube voltage and the first tube current increases. The irradiation time of the first X-ray pulse is proportional to the time during which the X-ray source emits X-rays, and the longer the irradiation time of the first X-ray pulse, the greater the X-ray irradiation dose. Furthermore, the brightness information of the first radiographic image may become brighter as the irradiation dose increases. However, this is not limited thereto, and the brightness information of the first radiographic image may become darker as the irradiation dose increases. The first irradiation condition calculation unit 203 may determine first irradiation conditions including at least one of the first tube voltage, the first tube current, and the irradiation time of the first X-ray pulse so that the brightness information of the first radiographic image is similar to predetermined brightness information. The first irradiation conditions may be different from the predetermined irradiation conditions. However, in certain cases, the first irradiation conditions may be the same as the predetermined irradiation conditions.

[0080] The irradiation control unit 204 can control the dose of radiation based on the first irradiation condition. The irradiation control unit 204 can be included in the control unit 200. The irradiation control unit 204 can control the operation of the radiation emitting unit 111 based on the first irradiation condition including at least one of a first tube voltage, a first tube current, and an irradiation time of the first X-ray pulse acquired from the first irradiation condition calculation unit 203.

[0081] The radiation irradiator 111 can irradiate the subject with radiation based on the first irradiation condition. The image acquirer 112 can acquire a second radiation image based on radiation based on at least one of the determined tube voltage, tube current, and X-ray pulse irradiation time. The second radiation image may be a radiation image generated after the first radiation image. The second radiation image may be included in a series of radiation images. The second radiation image may include at least one frame image in a moving image.

[0082] Furthermore, if the first radiation image is an image based on predetermined irradiation conditions, the second radiation image may be an image based on the first irradiation conditions. Since the subject appearing in the second radiation image is similar to the predetermined brightness information, the subject may appear clearly in the second radiation image. Therefore, the user can easily diagnose the patient based on the second radiation image. However, the second radiation image may not be based on the minimum radiation dose. The radiation image capturing device 100 may further perform the following process to maintain image quality while utilizing the minimum radiation dose.

[0083] The second irradiation condition calculation unit 205 may be included in the control unit 200. When the imaging region of the subject is fixed, the second irradiation condition calculation unit 205 may determine the second irradiation condition based on the second radiation image generated under the first irradiation condition. The second irradiation condition may be an irradiation condition for achieving a minimum dose while maintaining image quality. The second irradiation condition may be different from the first irradiation condition. However, in certain cases, the second irradiation condition may be the same as the first irradiation condition. The second irradiation condition may include at least one of a second tube voltage, a second tube current, and an irradiation time of the second X-ray pulse. The second irradiation condition may be a minimum irradiation condition for maintaining image quality of the fixed imaging region similar to that of the image obtained under the first irradiation condition.

[0084] The value obtained by subtracting the radiation dose based on the second irradiation condition from the radiation dose based on the first irradiation condition may be equal to or less than 70% of the radiation dose based on the first irradiation condition. That is, the radiation dose based on the second irradiation condition may be equal to or greater than 30% of the radiation dose based on the first irradiation condition. Since the radiation dose based on the second irradiation condition is smaller than the radiation dose based on the first irradiation condition, the patient or user may be exposed to less radiation. However, the radiographic imaging device 100 of the present disclosure can provide images of the same quality, thereby protecting the health of the patient and user while increasing convenience for the user.

[0085] The dose reducing unit 206 can reduce or maintain the radiation dose based on the second irradiation condition. The dose reducing unit 206 can be included in the control unit 200. The dose reducing unit 206 can be independent of the irradiation control unit 204. However, the present invention is not limited thereto, and the dose reducing unit 206 can have the same configuration as the irradiation control unit 204.

[0086] The dose reducing unit 206 can control the radiation dose based on the second irradiation condition, and can control the operation of the radiation emitting unit 111 based on the second irradiation condition including at least one of the second tube voltage, the second tube current, and the irradiation time of the second X-ray pulse acquired from the second irradiation condition calculating unit 205.

[0087] The radiation emitting unit 111 may irradiate the subject with radiation based on the second irradiation condition. The image acquiring unit 112 may acquire a third radiation image based on radiation based on at least one of the determined second tube voltage, second tube current, and second X-ray pulse irradiation time. The third radiation image may be a radiation image generated after the second radiation image. The third radiation image may be included in a series of radiation images. The third radiation image may include at least one frame image in a moving image.

[0088] Furthermore, if the second radiographic image is an image based on the first irradiation condition, the third radiographic image may be an image based on the second irradiation condition. The third radiographic image may maintain substantially the same quality as the second radiographic image. That is, the sharpness and noise of the subject appearing in the third radiographic image may be substantially the same as the sharpness and noise of the subject appearing in the second radiographic image. However, the dose of radiation irradiated to the subject to obtain the third radiographic image may be smaller than or the same as the dose of radiation irradiated to the subject to obtain the second radiographic image.

[0089] When the dose is reduced by the dose reducing unit 206, the first irradiation condition calculation unit 203 can be deactivated. That is, the radiographic imaging device 100 does not need to acquire the first irradiation condition by the first irradiation condition calculation unit 203. The radiographic imaging device 100 can adjust the subject of successive radiographic images not to match predetermined brightness information. The radiographic imaging device 100 can capture successive radiographic images based on the second irradiation condition. The radiographic imaging device 100 can capture a third radiographic image using the minimum dose based on the second irradiation condition. The condition for acquiring the second irradiation condition is that the subject is fixed. If the subject does not move, high-quality radiographic images can be acquired even using the minimum dose. This reduces side effects of radiation on the user and patient.

[0090] Furthermore, the radiation image capturing device 100 may generate an improved current frame image by accumulating and averaging pixel values ​​included in a current frame image included in the third radiation image and a previous frame image included in the third radiation image output by the dose reducing unit 206. In the present disclosure, the pixel value may be a pixel value of a pixel included in a display, or may be a pixel value indicating the degree of excitation by radiation of one of a plurality of pixels included in the image acquiring unit 112. The pixel value may have a value of 10 bits or more and 16 bits or less.

[0091] As already described, the third radiation image may include at least one frame image. The third radiation image may include a current frame image 830 and a previous frame image 820. The current frame image may be the frame most recently acquired by the image acquisition unit 112. The previous frame image 820 may be at least one frame image acquired before the current frame image. The previous frame image 820 may include a previous frame image 822 and an (n-2) frame image 821, etc. The previous frame image may be the frame image immediately before the current frame image.

[0092] The radiation imaging device 100 may generate an improved current frame image by accumulating and averaging a current frame image and a predetermined number of previous frame images. The predetermined number may be equal to or greater than 1. The predetermined number may refer to the number of frames. The radiation imaging device 100 may cumulatively average the pixel value of one pixel in the current frame image and the pixel value of the previous frame image at a position corresponding to the one pixel in the current frame image. The radiation imaging device 100 may acquire a pixel value included in the improved current frame image by accumulating and averaging the pixel values ​​of corresponding pixels in the current frame image and the previous frame image. Corresponding pixels mean that the position (coordinate value) of a pixel in the current frame image and the position (coordinate value) of a pixel in the previous frame image are the same. The radiation imaging device 100 may generate an improved current frame image by acquiring a cumulative average value of all pixels included in the current frame image and all pixels included in the previous frame image.

[0093] As described above, since the object does not move, the change in pixel value of pixels at the same position in consecutive frame images is small. Therefore, when an improved current frame image is obtained by performing cumulative averaging as described above, the influence of noise can be minimized. This is because noise occurs when pixel values ​​of pixels change significantly.

[0094] The radiographic imaging device 100 may further include an image post-processing unit 207 that performs post-processing on the third radiographic image output at the reduced dose by the dose reduction unit 206. The image post-processing unit 207 may adjust at least one of brightness information and contrast information of at least one of the first, second, and third radiographic images so as to maintain a predetermined brightness based on predetermined brightness information. Unlike the first irradiation condition calculation unit 203, the image post-processing unit 207 does not determine irradiation conditions for controlling the radiation irradiation unit 111, but may process the radiographic image using software.

[0095] The image post-processing unit 207 of the radiographic imaging device 100 may adjust pixel values ​​of the third radiographic image so that brightness information of the third radiographic image resembles predetermined brightness information. The radiographic imaging device 100 may adjust all pixel values ​​included in the third radiographic image using the same ratio or the same subtraction value, so that brightness information of the third radiographic image may resemble predetermined brightness information. The predetermined brightness information may be brightness information stored in memory.

[0096] However, the predetermined brightness information is not limited thereto, and may be a value measured by the image brightness information extraction unit 202. For example, the radiographic imaging device 100 may measure brightness information of at least one of the first and second radiographic images using the image brightness information extraction unit 202. The radiographic imaging device 100 may measure brightness information of the second radiographic image. The image post-processing unit 207 of the radiographic imaging device 100 may adjust pixel values ​​of the third radiographic image so that the brightness information of the third radiographic image is similar to the brightness information of the second radiographic image. The image post-processing unit 207 may adjust at least one of the brightness information and contrast information of the third radiographic image so that the brightness information is similar to at least one of the brightness information and contrast information of the second radiographic image. The radiographic imaging device 100 may adjust all pixel values ​​included in the third radiographic image using the same ratio or the same subtraction value, so that the brightness information of the third radiographic image may be similar to the brightness information of the second radiographic image.

[0097] For reference, in this disclosure, "similar" may mean that the difference between the two pieces of information is equal to or smaller than a predetermined range. For example, "the brightness information of the second radiographic image is similar to the brightness information of the third radiographic image" may mean that the absolute value of the difference between the brightness information of the second radiographic image and the brightness information of the third radiographic image is equal to or smaller than a predetermined range. The predetermined range may be equal to or larger than 0.

[0098] Hereinafter, the operation method of the radiation image capturing apparatus will be described in detail.

[0099] FIG. 3 is a flowchart showing an operation method of the radiation image capturing apparatus according to an embodiment of the present disclosure.

[0100] As already described, the radiographic imaging device 100 may include a radiation irradiator 111 that irradiates a subject with radiation. The radiographic imaging device 100 may also include an image acquirer 112 that receives radiation that has been irradiated from the radiation irradiator 111 and passed through the subject, and generates successive radiographic images.

[0101] The radiation image capturing apparatus 100 may include a control unit 200 that controls the radiation emitting unit and the image acquiring unit 112. The control unit 200 may perform the following operations.

[0102] The control unit 200 may execute step 310 of acquiring a first radiation image. The image output unit 201 may output the first radiation image. The first radiation image may be included in a series of radiation images. The first radiation image may include at least one frame image. The first radiation image may be an image acquired by image processing at least one frame image. The radiation image capturing device 100 may store predetermined irradiation conditions. The predetermined irradiation conditions may include at least one of a predetermined tube voltage, a predetermined overcurrent, and a predetermined X-ray pulse irradiation time. The radiation image capturing device 100 may control the radiation emitting unit 111 based on the predetermined irradiation conditions to irradiate the subject with radiation. The image acquiring unit 112 may acquire the first radiation image.

[0103] The control unit 200 may perform step 320 of acquiring brightness information based on a first radiation image included in the sequence of radiation images. The brightness information may be acquired by the image brightness information extraction unit 202.

[0104] The control unit 200 may perform step 330 of determining a first illumination condition based on the brightness information using a first algorithm. As described above, the first illumination condition may be determined by the first illumination condition calculation unit 203.

[0105] To further explain steps 320 and 330, please refer to FIG.

[0106] FIG. 4 is a flowchart showing an operation method of the radiation image capturing apparatus according to an embodiment of the present disclosure.

[0107] The step 320 of acquiring brightness information may include the following steps.

[0108] The control unit 200 may perform step 410 of acquiring brightness information by averaging pixel values ​​included in at least a portion of the first radiographic image. In order to acquire brightness information by averaging pixel values ​​included in at least a portion of the first radiographic image, the control unit 200 may perform step 411 of acquiring a region where an object appears from the first radiographic image based on an object region acquisition model. The control unit 200 may determine the region where an object appears from the first radiographic image based on a predetermined algorithm. The predetermined algorithm may be a machine learning model or a rule-based model. The control unit 200 may determine the region where an object appears based on information about the object and the first radiographic image. Here, the information about the object may include at least one of the thickness of the object, the type of the object, the location of the object, the material of the object, and the density of the object. The predetermined algorithm may be selected based on the information about the object. The control unit 200 may determine the region where an object appears from the first radiographic image based on the selected predetermined algorithm. The region where an object appears may be a partial region of the first radiographic image. The region where an object appears may refer to an area within the outline of the object appearing in the first radiographic image.

[0109] The control unit 200 may perform step 412 of acquiring brightness information by averaging pixel values ​​included in the region where the object appears. However, without being limited thereto, the control unit 200 may acquire at least one of a minimum value, an average value, and a median value of pixel values ​​of pixels in the region where the object appears as brightness information. However, without being limited thereto, the control unit 200 may acquire at least one of a minimum value, an average value, and a median value of pixel values ​​of all pixels of the first radiological image as brightness information.

[0110] The control unit 200 may perform the following process to execute the step 330 of determining the first irradiation condition.

[0111] If the brightness information is smaller than predetermined first critical brightness information, the control unit 200 may perform step 420 of determining first irradiation conditions so that the brightness information is increased. Also, if the brightness information is larger than the predetermined first critical brightness information, the control unit 200 may perform step 440 of determining first irradiation conditions so that the brightness information is decreased. Also, if the brightness information is equal to the predetermined first critical brightness information, the control unit 200 may perform step 430 of determining the first irradiation conditions as predetermined irradiation conditions. The predetermined irradiation conditions may be irradiation conditions used to acquire the first radiographic image.

[0112] As described above, the first irradiation condition may include at least one of the first tube voltage, the first tube current, and the irradiation time of the first X-ray pulse. The first irradiation condition calculation unit 203 may determine at least one of the first tube voltage, the first tube current, and the irradiation time of the first X-ray pulse of the radiation irradiator 111 based on brightness information of the first radiographic image. For example, the X-ray irradiation dose may increase as at least one of the first tube voltage and the first tube current increases. The irradiation time of the first X-ray pulse is proportional to the time it takes for the X-ray source to emit X-rays, and the longer the irradiation time of the first X-ray pulse, the higher the X-ray irradiation dose. At least one of the first tube voltage, the first battery, and the irradiation time of the first X-ray pulse may have a linear relationship with the irradiation dose. However, the relationship is not limited thereto, and at least one of the first tube voltage, the first tube current, and the irradiation time of the first X-ray pulse may have a nonlinear relationship with the irradiation dose.

[0113] The control unit 200 may determine at least one of the first tube voltage, the first tube current, and the irradiation time of the first X-ray pulse included in the predetermined irradiation conditions by modifying at least one of the predetermined tube voltage, the predetermined tube current, and the predetermined X-ray pulse irradiation time included in the predetermined irradiation conditions based on at least one of the predetermined first irradiation condition function and the first irradiation condition table. The first irradiation condition function or the first irradiation condition table may be a function or a table for determining the first irradiation conditions based on the predetermined irradiation conditions and brightness information of the first radiographic image.

[0114] According to an embodiment of the present disclosure, the brightness information of the first radiographic image may be brighter as the radiation dose increases. In this case, if the brightness information is smaller than predetermined first critical brightness information, the first irradiation condition may be greater than the predetermined irradiation condition. That is, if the brightness information is smaller than the predetermined first critical brightness information, at least one of the first tube voltage, the first tube current, and the first X-ray pulse irradiation time included in the first irradiation condition may be greater than at least one of the predetermined tube voltage, the predetermined tube current, and the predetermined X-ray pulse irradiation time included in the predetermined irradiation condition. Furthermore, if the brightness information is greater than the predetermined first critical brightness information, the first irradiation condition may be less than the predetermined irradiation condition. That is, if the brightness information is greater than the predetermined first critical brightness information, at least one of the first tube voltage, the first tube current, and the first X-ray pulse irradiation time included in the first irradiation condition may be less than at least one of the predetermined tube voltage, the predetermined tube current, and the predetermined X-ray pulse irradiation time included in the predetermined irradiation condition. Furthermore, if the brightness information is the same as predetermined first critical brightness information, the first irradiation condition may be the same as the predetermined irradiation condition, i.e., if the brightness information is the same as predetermined first critical brightness information, at least one of the first tube voltage, the first tube current, and the first X-ray pulse irradiation time included in the first irradiation condition may be the same as at least one of the predetermined tube voltage, the predetermined tube current, and the predetermined X-ray pulse irradiation time included in the predetermined irradiation condition.

[0115] However, without being limited thereto, according to various embodiments of the present disclosure, the brightness information of the first radiographic image may become darker as the exposure dose increases. For example, the control unit 200 may use an inverted image obtained by inverting pixel values ​​of the image acquired from the image acquisition unit 112. Therefore, the brightness information of the first radiographic image, which is an inverted image, may become darker as the exposure dose increases. In this case, if the brightness information is smaller than the predetermined first critical brightness information, the first irradiation condition may be smaller than the predetermined irradiation condition. That is, if the brightness information is smaller than the predetermined first critical brightness information, at least one of the first tube voltage, the first tube current, and the first X-ray pulse irradiation time included in the first irradiation condition may be smaller than at least one of the predetermined tube voltage, the predetermined tube current, and the predetermined X-ray pulse irradiation time included in the predetermined irradiation condition. Furthermore, if the brightness information is larger than the predetermined first critical brightness information, the first irradiation condition may be larger than the predetermined irradiation condition. That is, when the brightness information is greater than the predetermined first critical brightness information, at least one of the first tube voltage, the first tube current, and the first X-ray pulse irradiation time included in the first irradiation condition may be greater than at least one of the predetermined tube voltage, the predetermined tube current, and the predetermined X-ray pulse irradiation time included in the predetermined irradiation condition.

[0116] As described above, the control unit 200 may determine the first irradiation conditions, including at least one of the first tube voltage, the first tube current, and the irradiation time of the first X-ray pulse, so that the brightness information of the first radiographic image is identical to the predetermined brightness information. The first irradiation conditions may be different from the predetermined irradiation conditions. However, in certain cases, the first irradiation conditions may be identical to the predetermined irradiation conditions. The control unit 200 may determine the brightness information of radiographic images generated after the first radiographic image is identical to the predetermined brightness information based on the first irradiation conditions.

[0117] The control unit 200 can repeatedly acquire the first irradiation conditions at a predetermined cycle. The radiographic imaging device 100 can provide moving images, and the subject can continuously change. The radiographic imaging device 100 can continuously acquire the first irradiation conditions and irradiate radiation accordingly, thereby providing the user with an optimal radiographic image.

[0118] 3, the control unit 200 may perform step 340 of controlling the radiation dose based on the first irradiation condition. Step 340 may be performed by the irradiation control unit 204. As described above, the radiation dose may be determined by at least one of the first tube voltage, the first tube current, and the irradiation time of the first X-ray pulse, which are included in the first irradiation condition.

[0119] The control unit 200 may execute step 350 of acquiring a second radiographic image included in the series of radiographic images and generated based on the first irradiation condition. The second radiographic image may be a radiographic image generated after the first radiographic image. The second radiographic image may be included in the series of radiographic images. The second radiographic image may include at least one frame image in a moving image. Furthermore, if the first radiographic image is an image based on predetermined irradiation conditions, the second radiographic image may be an image based on the first irradiation condition. Since an object appearing in the second radiographic image has similar brightness information to the predetermined brightness information, the object may appear clearly in the second radiographic image. Therefore, a user can easily diagnose a patient based on the second radiographic image. However, the second radiographic image may not be based on the minimum radiation dose. The radiographic image capturing device 100 may further execute the following process to maintain image quality while utilizing the minimum radiation dose.

[0120] The control unit 200 may perform step 360 of acquiring motion presence / absence information indicating whether the imaging region of the subject is stationary. The motion presence / absence information may be acquired from a user through the input unit 250. For example, the user may input the motion presence / absence information to the radiation image capturing apparatus 100 after confirming that the subject is stationary.

[0121] However, the present invention is not limited thereto, and the motion presence / absence information may be automatically acquired. More specifically, the step 360 of acquiring the motion presence / absence information may include the following steps.

[0122] The control unit 200 may execute a step of determining the presence / absence of motion information to indicate that the imaging region of the subject is not immobilized if the time taken to acquire at least one of the first and second radiographic images is less than a predetermined critical time. The critical time may be a time sufficient for the patient to be immobilized. In the primary environment, the subject may be a patient undergoing surgery. The patient may be anesthetized for surgery. When the patient is placed in the radiographic imaging device, the patient hardly moves. Therefore, if the time taken from the start of acquisition of at least one of the first and second radiographic images by the radiographic imaging device 100 is less than a predetermined critical time, the control unit 200 may determine the presence / absence of motion information to indicate that the imaging region of the subject is not immobilized. Here, the start time of acquisition of the first radiographic image may refer to the start time of acquisition of the first radiographic image of the subject. Furthermore, the start time of acquisition of the second radiographic image may refer to the start time of acquisition of the radiographic image under the first irradiation condition. The start time of acquisition of the second radiographic image may refer to the end time of acquisition of the first radiographic image. The difference between the time when the first radiographic image begins to be acquired and the time when the second radiographic image begins to be acquired may be within 5 seconds.

[0123] If the time taken to capture at least one of the first and second radiographic images is equal to or longer than a predetermined critical time, the control unit 200 may determine the motion information to indicate that the imaging region of the subject is fixed. That is, the radiographic imaging device 100 may assume that the subject is fixed after the predetermined critical time.

[0124] If the motion presence / absence information indicates that the imaging region of the subject is fixed, the control unit 200 may execute step 370 of determining second irradiation conditions based on the second radiation image using a second algorithm. Step 370 may be executed by the second irradiation condition calculation unit 205.

[0125] The first algorithm for determining the first illumination condition and the second algorithm for determining the second illumination condition may be different from each other. In the following, reference will be made to FIG. 5 to describe step 370 of determining the second illumination condition.

[0126] Fig. 5 is a flowchart showing the operation of the radiographic imaging device according to an embodiment of the present disclosure, and Fig. 6 is a diagram for explaining downsampling according to an embodiment of the present disclosure.

[0127] 5 and 6, the step 370 of determining the second irradiation condition may include the following operation. The control unit 200 may perform a step of downsampling the second radiation image 610 in units of patches 611 of a predetermined size to obtain a downsampled image 620. The patches 611 of the predetermined size may be smaller than the second radiation image 610. If the size of the second radiation image 610 is n×m, the size of the patches 611 of the predetermined size may be a×b. n may be the number of pixels on the horizontal axis included in the second radiation image 610, and m may be the number of pixels on the vertical axis included in the second radiation image 610. Furthermore, a may be the number of pixels on the horizontal axis of the patches 611 of the predetermined size, and b may be the number of pixels on the vertical axis of the patches 611 of the predetermined size. n may be greater than or equal to a, and m may be greater than or equal to b.

[0128] The control unit 200 may determine one of the average, minimum, maximum, and median of pixel values ​​of pixels included in a patch 611 of a predetermined size in the second radiation image 610 as the pixel value of one pixel 621 of the downsampled image 620. The control unit 200 may determine one of the average, minimum, maximum, and median of pixel values ​​of pixels included in a patch 612 of a next predetermined size in the second radiation image 610 as the pixel value of one pixel 622 of the downsampled image 620. The sizes of the patch 611 of the predetermined size and the patch 612 of the next predetermined size may be the same or may not overlap each other. The control unit 200 may obtain the downsampled image 620 by repeating the above process for the entire second radiation image 610.

[0129] Although the patches 611 and 612 of the predetermined size do not overlap each other in the above description, the present invention is not limited thereto. The patches of the predetermined size may overlap each other. For example, the control unit 200 may determine one of the average, minimum, maximum, and median of pixel values ​​of pixels included in the patch 631 of the predetermined size from the second radiological image 630 as the pixel value of one pixel 641 of the downsampled image 640. The control unit 200 may determine one of the average, minimum, maximum, and median of pixel values ​​of pixels included in the patch 632 of the next predetermined size from the second radiological image 630 as the pixel value of one pixel 642 of the downsampled image 640. The sizes of the patch 631 of the predetermined size and the patch 632 of the next predetermined size may be the same or may overlap each other. The control unit 200 may obtain the downsampled image 640 by repeating the above process for the entire second radiological image 630. If patches of a predetermined size are downsampled in an overlapping manner, downsampled image 640 may be larger than downsampled image 620 .

[0130] Although downsampling is performed on the entire region of the second radiographic image 630 in the above example, the present invention is not limited to this. The control unit 200 may perform downsampling on a region of interest in the second radiographic image to obtain a downsampled image. The region of interest may be a region selected by a user or a region automatically selected by the radiographic image capturing apparatus 100. For example, the region of interest may be a region in which an object appears. The region in which an object appears has already been described, so a duplicated description will be omitted.

[0131] The control unit 200 may perform a step of acquiring a minimum pixel value among pixel values ​​included in the downsampled image (one of 620 and 640). If the minimum pixel value is greater than predetermined second critical brightness information, the control unit 200 may perform a step of determining second illumination conditions so that the minimum pixel value is equal to the second critical brightness information. If the minimum pixel value is less than or equal to the predetermined second critical brightness information, the control unit 200 may perform a step of determining the second illumination conditions to be equal to the first illumination conditions. If the minimum pixel value is less than or equal to the predetermined second critical brightness information, the control unit 200 may not determine the second illumination conditions. The second critical brightness information may be acquired based on the performance of the detector. The second critical brightness information is the smallest pixel value that can be processed successfully by at least one of the image acquisition unit 112 and the image post-processing unit 207 included in the control unit 200, and may be a predefined constant. If the performance of the image acquisition unit 112 and the image post-processing unit 207 is poor, the pixel may contain noise components, and values ​​below a certain pixel value may be values ​​due to noise rather than radiation. Therefore, the second critical brightness information may be a value associated with the minimum radiation dose that can indicate that the pixel has been excited by radiation. That is, the better the performance of the image acquisition unit 112 and the image post-processing unit 207, the smaller the second critical brightness information may be.

[0132] Referring to FIG. 7, the step of determining the second illumination condition so that the minimum pixel value is equal to the second critical brightness information will be described.

[0133] FIG. 7 is a flowchart illustrating a process for obtaining a second irradiation condition according to an embodiment of the present disclosure.

[0134] The step of determining the second illumination condition so that the minimum pixel value is equal to the second critical brightness information may include the following steps.

[0135] The control unit 200 may perform step 710 of determining a reduction rate based on the minimum pixel value and second critical brightness information. The second critical brightness information is the smallest pixel value that can be processed successfully by at least one of the image acquiring unit 112 and the image post-processing unit 207 included in the control unit 200, and may be a predefined constant. The reduction rate may be greater than or equal to 0 and less than or equal to a predetermined maximum reduction rate. The maximum reduction rate may be greater than or equal to 65% and less than or equal to 75%. For example, the maximum reduction rate may be 70%. The unit of the reduction rate may be, but is not limited to, %.

[0136] The control unit 200 can obtain the reduction rate based on the following formula:

[0137] Reduction rate = min(max(1-2nd critical brightness information / minimum pixel value, 0), maximum reduction rate)*100

[0138] The radiation dose based on the second irradiation condition may be greater than or equal to 30% of the radiation dose based on the first irradiation condition. If the reduced dose is determined to be the maximum reduction rate of 70%, the radiation dose based on the second irradiation condition may be 30% of the radiation dose based on the first irradiation condition.

[0139] The control unit 200 may execute step 720 of determining the second irradiation conditions so that the radiation irradiation unit irradiates a dose obtained by subtracting the dose according to the first irradiation condition multiplied by the reduction rate from the dose according to the first irradiation condition.

[0140] The second irradiation condition may include at least one of a second tube voltage, a second tube current, and an irradiation time of the second X-ray pulse. The controller 200 may determine at least one of the second tube voltage, the second tube current, and the irradiation time of the second X-ray pulse based on the reduction rate determined in step 710. For example, the X-ray irradiation dose may increase as at least one of the second tube voltage and the second tube current increases. The irradiation time of the second X-ray pulse is proportional to the time during which the X-ray source emits X-rays, and the X-ray irradiation quality may increase as the irradiation time of the second X-ray pulse increases. Furthermore, the brightness information of the radiographic image may increase as the irradiation dose increases. However, the present invention is not limited thereto, and the brightness information of the radiographic image may decrease as the irradiation dose increases. The controller 200 may determine the second irradiation condition, including at least one of the second tube voltage, the second tube current, and the irradiation time of the second X-ray pulse, based on the reduction rate. The second irradiation condition may be different from the first irradiation condition. However, in certain cases, the second irradiation condition may be the same as the first irradiation condition.

[0141] At least one of the second tube current and the irradiation time of the second X-ray pulse may have a linear relationship with the exposure dose. Furthermore, the second tube voltage may have a nonlinear relationship with the exposure dose. The controller 200 may determine at least one of the second tube current and the irradiation time of the second X-ray pulse by decreasing the decrease rate from at least one of the first tube current and the irradiation time of the first X-ray pulse. However, the present invention is not limited thereto. The controller 200 may determine at least one of the second tube current and the irradiation time of the second X-ray pulse corresponding to the decrease rate by applying a predetermined decrease rate determination function or decrease rate determination table to at least one of the first tube current and the irradiation time of the first X-ray pulse. Furthermore, the controller 200 may obtain a voltage decrease rate corresponding to the decrease rate based on the voltage decrease rate determination function or voltage decrease rate determination table. The controller 200 may determine the second tube voltage by decreasing the first tube voltage by the voltage decrease rate.

[0142] 3, the control unit 200 may perform step 380 of controlling the radiation dose based on the second irradiation condition. Step 380 may be performed by at least one of the dose reduction unit 206 and the irradiation control unit 204. As already described, the second irradiation condition may be determined based on the first irradiation condition and the reduction rate. The radiation dose based on the second irradiation condition may be smaller than or equal to the radiation dose based on the first irradiation condition. That is, the control unit 200 may determine the radiation dose according to the second irradiation condition using the following formula:

[0143] Dose under the second irradiation condition = Dose under the first irradiation condition * (1 - reduction rate / 100)

[0144] The control unit 200 may execute step 390 of acquiring a third radiographic image included in the sequence of radiographic images and generated based on the second irradiation condition. The third radiographic image may be a radiographic image generated after the second radiographic image. The third radiographic image may be included in the sequence of radiographic images. The third radiographic image may include at least one frame image in a moving image.

[0145] Furthermore, if the second radiographic image is an image based on the first irradiation condition, the third radiographic image may be an image based on the second irradiation condition. The third radiographic image may maintain substantially the same quality as the second radiographic image. That is, the sharpness and noise of the subject appearing in the third radiographic image may be substantially the same as the sharpness and noise of the subject appearing in the second radiographic image. However, the dose of radiation irradiated to the subject to obtain the third radiographic image may be smaller than or the same as the dose of radiation irradiated to the subject to obtain the second radiographic image.

[0146] The control unit 200 can repeatedly acquire the second irradiation conditions at a predetermined cycle. The radiographic imaging device 100 can provide moving images, and the subject can continuously change. The radiographic imaging device 100 continuously acquires the second irradiation conditions, thereby irradiating radiation, thereby obtaining radiographic images of the subject with a low dose and maintaining high quality of the radiographic images.

[0147] In the radiographic imaging device 100 according to an embodiment of the present disclosure, the control unit 200 can fix the second irradiation condition based on a user input or a predetermined condition. When the control unit 200 fixes the second irradiation condition, the control unit 200 can be expected to maintain a low radiation dose because it does not change the second irradiation condition when an object other than the subject enters the imaging area. For example, when a medical device or the like enters the imaging area, the radiographic imaging device 100 can maintain a low radiation dose under the second irradiation condition without changing the radiation dose to change the brightness of the radiographic image.

[0148] The third radiographic image may be post-processed to improve the quality of the image. The following describes how the third radiographic image is post-processed.

[0149] FIG. 8 is a diagram for explaining the operation of the radiographic image capturing apparatus according to an embodiment of the present disclosure.

[0150] The step 390 of acquiring a third radiation image may include the following process: The control unit 200 may perform a step of accumulating and averaging pixel values ​​included in at least a portion of a current frame image 830 included in the third radiation image and pixel values ​​included in at least a portion of a previous frame image 820 included in the third radiation image to generate an improved current frame image 840. The step of acquiring the improved current frame image 840 may be performed by an image post-processing unit 207 included in the control unit 200.

[0151] As already described, the third radiation image may include a current frame image 830 and a previous frame image 820. The current frame image may be the frame most recently acquired by the image acquisition unit 112. The previous frame image 820 may be at least one frame image acquired before the current frame image. The previous frame image 820 may include a previous frame image 822 and an (n-2) frame image 821. The previous frame image may be the frame image immediately before the current frame image.

[0152] The control unit 200 may generate an improved current frame image 840 by accumulating and averaging the current frame image 830 and a predetermined number of previous frame images 820. The predetermined number may be equal to or greater than 1. The predetermined number may refer to the number of frames. For convenience of explanation, the following description will be given assuming that the predetermined number is 1. The same explanation may also be applied to cases where the predetermined number is 2 or more.

[0153] The control unit 200 may cumulatively average the pixel value of one pixel in the current frame image 830 and the pixel value of the previous frame image 820 at a position corresponding to the one pixel in the current frame image. The radiation image capturing device 100 may acquire a pixel value included in the improved current frame image 840 by cumulatively averaging the pixel values ​​of pixels at corresponding positions in the current frame image 830 and the previous frame image 820. Pixels at corresponding positions mean that the pixel positions (coordinate values) in the current frame image 830 and the previous frame image 820 are the same. The control unit 200 may generate the improved current frame image 840 by acquiring a cumulative average value of all pixels included in the current frame image 830 and all pixels included in the previous frame image 820. However, the present invention is not limited to this, and the control unit 200 may generate the improved current frame image 840 by acquiring a cumulative average value of pixel values ​​of pixels included in at least a portion of the current frame image 830 and the previous frame image 820. At least a portion of the current frame image 830 may be at least one of a region of interest or a region in which an object appears.

[0154] As described above, since an object does not move, the change in pixel value of pixels at the same position in consecutive frame images is small. Therefore, when an improved current frame image is obtained by performing the cumulative average as described above, the influence of noise can be minimized. This is because noise occurs when the pixel value of a pixel changes significantly.

[0155] Fig. 9 is a flowchart showing the operation of a radiographic image capturing apparatus according to an embodiment of the present disclosure. Fig. 10 is a diagram for explaining the operation of a radiographic image capturing apparatus according to an embodiment of the present disclosure. Fig. 11 is a diagram for explaining the operation of a radiographic image capturing apparatus according to an embodiment of the present disclosure. Fig. 12 is a diagram for explaining the operation of a radiographic image capturing apparatus according to an embodiment of the present disclosure.

[0156] 9 to 12 can be executed by the image post-processing unit 207 included in the control unit 200. The image post-processing unit 207 does not control the radiation irradiation unit 111, but can correct the acquired first to third radiation images using software to output radiation images of improved quality.

[0157] The image post-processing unit 207 included in the control unit 200 may further perform the following process when performing the step 390 of acquiring the third radiation image.

[0158] Referring to FIG. 9, the control unit 200 may perform step 910 of generating a motion detection image including motion detection information for each pixel of a difference image obtained by subtracting a current frame image included in the third radiation image from a previous frame image included in the third radiation image.

[0159] 9 and 10, the control unit 200 can generate a motion-detected image by performing threshold processing on the difference image. As a result, as shown in FIG. 10, a motion-detected image 1010 can be generated from the noise-processed current frame image 830 and the previous frame image 820. Here, the motion-detected image 1010 can be obtained based on a subtraction image obtained by subtracting the previous frame image 820 from the current frame image 830.

[0160] The control unit 200 generates a difference image by subtracting the current frame image 830, which has been subjected to noise processing, i.e., noise reduction and noise stabilization processing, from the previous frame image 820. To reduce noise, the control unit 200 may obtain the sum of absolute differences by adding the absolute values ​​of the differences between the pixel values ​​of any two pixels from the upper left, upper, upper right, left, right, lower left, lower, and lower right adjacent to the center pixel to be noise reduced. The selected adjacent pixels may be appropriately determined according to needs and requirements. For example, the control unit 200 may calculate the sum of absolute values ​​of the differences between the center pixel and any two pixels from the upper left, upper, upper right, left, right, lower left, lower, and lower right adjacent to the center pixel.

[0161] For example, the control unit 200 calculates the sum of the absolute values ​​of the difference between the pixel value of the central pixel and the pixel value of the upper left pixel and the difference between the pixel value of the central pixel and the pixel value of the upper pixel (A1), the sum of the absolute values ​​of the difference between the pixel value of the central pixel and the pixel value of the upper left pixel and the difference between the pixel value of the central pixel and the pixel value of the upper pixel (A2), the sum of the absolute values ​​of the difference between the pixel value of the central pixel and the pixel value of the upper left pixel and the difference between the pixel value of the central pixel and the pixel value of the pixel The sum of absolute values ​​of the difference between the pixel value of the cell and the pixel value of the pixel to the right (A4), the sum of absolute values ​​of the difference between the pixel value of the central pixel and the pixel value of the upper left pixel and the difference between the pixel value of the central pixel and the pixel value of the lower left pixel (A5), the sum of absolute values ​​of the difference between the pixel value of the central pixel and the pixel value of the upper left pixel and the pixel value of the central pixel and the pixel value of the pixel value of the lower right pixel (A6), and the sum of absolute values ​​of the difference between the pixel value of the central pixel and the pixel value of the upper left pixel and the pixel value of the central pixel and the pixel value of the lower right pixel (A7) can be obtained. The control unit 200 can obtain a sum of absolute values ​​of a difference between the pixel value of the center pixel and the pixel value of the upper pixel and a difference between the pixel value of the center pixel and the pixel value of the upper right pixel (A8); a sum of absolute values ​​of a difference between the pixel value of the center pixel and the pixel value of the upper pixel and a difference between the pixel value of the center pixel and the pixel value of the left pixel (A9); a sum of absolute values ​​of a difference between the pixel value of the center pixel and the pixel value of the upper pixel and a difference between the pixel value of the center pixel and the pixel value of the right pixel (A10); a sum of absolute values ​​of a difference between the pixel value of the center pixel and the pixel value of the upper pixel and a difference between the pixel value of the center pixel and the pixel value of the lower left pixel (A11); a sum of absolute values ​​of a difference between the pixel value of the center pixel and the pixel value of the upper pixel and a difference between the pixel value of the center pixel and the pixel value of the lower right pixel (A12); and a sum of absolute values ​​of a difference between the pixel value of the center pixel and the pixel value of the upper pixel and a difference between the pixel value of the center pixel and the pixel value of the lower right pixel (A13). The control unit 200 can determine the sum of the absolute values ​​of the differences between the central pixel and the surrounding pixels through the above process.That is, the control unit 200 can obtain the sum of absolute values ​​(A1 to A29) through the above process. At this time, it can be determined that the pixel having the most similar direction to the center pixel is the one with the smaller sum of absolute values ​​(Ak). For example, if A1 is the smallest among A1 to A29, the upper left pixel and the upper pixel can be selected, and the direction proceeding to the upper left pixel, center pixel, and upper pixel in order can be selected.

[0162] Since impulse noise is a pixel having a particularly large absolute value compared to surrounding pixels, in order to eliminate this, the control unit 200 may update the pixel value of the center pixel to a noise-reduced pixel value by correcting the pixel value of the center pixel using pixel values ​​of two adjacent pixels that have the smallest sum of absolute values ​​of the differences between the pixel values ​​of the center pixel and the two selected adjacent pixels. For example, the control unit 200 may replace the pixel value of the center pixel with an average or median value of the pixel values ​​of the center pixel and the two selected pixels. By updating the pixel value of the center pixel in this manner while shifting the mask in sequence, noise reduction through pixel value updating may be performed.

[0163] Although the above describes an embodiment in which pixels surrounding a central pixel within a frame are considered, the present invention is not limited thereto. The control unit 200 may further use at least one of a frame immediately before the current frame and a frame immediately after the current frame. The frame immediately after the current frame may be an image acquired from the image acquisition unit 112 and acquired immediately after the current frame. The current frame may be a frame undergoing noise processing, and the frame immediately after may be a frame before noise processing. The previous frame may be a frame immediately before the current frame, for which noise processing has been completed.

[0164] The control unit 200 may obtain an absolute value of a difference between the pixel value of the central pixel of the current frame and any one of the central pixel of the immediately preceding frame at the same position as the central pixel of the current frame, and any one of the adjacent upper left, upper, upper right, left, right, lower left, lower, and lower right pixels. The control unit 200 may also obtain an absolute value of a difference between the pixel value of the central pixel of the current frame and any one of the adjacent upper left, upper, upper right, left, right, lower left, lower, and lower right pixels of the immediately succeeding frame at the same position as the central pixel of the current frame. The control unit 200 may select two pixels having the smallest sum of the two absolute values. The control unit 200 may replace the pixel value of the central pixel of the current frame with an average or median value of the pixel value of the central pixel of the current frame and the pixel value of the selected two pixels.

[0165] The control unit 200 may stabilize noise by reducing the deviation between noise in a noise-reduced current frame image and a previous frame image. For example, the amount of photons incident on each sensor for acquiring a radiographic image is not constant over time but appears randomly and is independent, so the noise characteristics of a radiographic image generally follow a Poisson distribution. In an embodiment of the present disclosure, in order to remove noise having Poisson distribution characteristics, the noise is approximated to noise having Gaussian distribution characteristics through the Anscombe transform. Because the Anscombe transform approximates to a Gaussian distribution with a standard deviation close to 1, the transformed data has a stable noise deviation.

[0166] The control unit 200 may generate a difference image by calculating the difference in pixel values ​​of each pixel at the same position for all pixels between the current frame image 830 and the previous frame image 820. The difference image may include information about the movement of the object and information about residual noise. Additionally, the generated difference image may be stabilized by using a mean filter or a median filter.

[0167] The controller 200 determines a critical pixel value for motion detection of the difference image and performs threshold processing based on the determined critical pixel value to detect the presence or absence of motion in each pixel, thereby generating a motion-detected image 1010. If the critical pixel value for motion detection is set too low, the motion detection sensitivity increases and the noise reduction level decreases. Conversely, if the critical pixel value is set too high, the motion detection sensitivity decreases and motion blur may occur. Because X-ray images are acquired under different dose conditions and subject characteristics, it is difficult to predict the pixel values ​​of the acquired images, and therefore it is necessary to set an appropriate critical pixel value depending on the pixel values.

[0168] The control unit 200 according to an embodiment of the present disclosure may apply an adaptive critical pixel value whose size varies depending on the size of the pixel value of each pixel in the difference image. For example, the critical pixel value for determining motion may be set to decrease as the pixel value of the pixel increases.

[0169] If the absolute value of a pixel value of a pixel included in the difference image is equal to or greater than a predetermined critical pixel value, the control unit 200 may set the pixel value of the corresponding pixel included in the motion-detecting image 1010 to "0," and, for example, if the absolute value of a pixel value of a pixel included in the difference image is less than the predetermined critical pixel value, the pixel value of the corresponding pixel included in the motion-detecting image 1010 may be "1." However, without being limited thereto, if the absolute value of a pixel value of a pixel included in the difference image is equal to or greater than the predetermined critical pixel value, the control unit 200 may set the pixel value of the corresponding pixel included in the motion-detecting image 1010 to "1," and, for example, if the absolute value of the pixel value of a pixel included in the difference image is less than the predetermined critical pixel value, the pixel value of the corresponding pixel included in the motion-detecting image 1010 may be "0."

[0170] The motion-sensitive image 1010 may include information regarding the presence or absence of motion for each pixel. For example, a pixel with motion may be set to have a value of "0," and a pixel with no motion may be set to have a value of "1." That is, all pixels in the motion-sensitive image 1010 may have a pixel value of 0 or 1, and a pixel with a value of 0 may indicate that there is motion relative to the previous frame image, and a pixel with a value of 1 may indicate that there is no motion relative to the previous frame image. However, the present invention is not limited to this.

[0171] The control unit 200 may generate an improved current frame image 840 based on the motion-detected image 1010. As described with reference to FIG. 8 , the control unit 200 may perform the step of generating the improved current frame image 840 by accumulating and averaging pixel values ​​included in at least a portion of the current frame image 830 included in the third radiation image and pixel values ​​included in at least a portion of the previous frame image 820 included in the third radiation image. In this case, the control unit 200 may further use the motion-detected image 1010. More specifically, for pixels in which motion is detected in the motion-detected image 1010, the control unit 200 may determine pixel values ​​of the current frame image 830 as pixel values ​​of the improved current frame image 840, and for pixels in which motion is not detected, may determine pixel values ​​of the improved current frame image 840 by accumulating and averaging pixel values ​​of the current frame image 830 and the previous frame image 820. However, the present invention is not limited thereto, and the control unit 200 may use a motion probability image instead of the motion-detected image 1010 to generate the improved current frame image 840.

[0172] Also, referring to FIG. 9, the control unit 200 may perform operation 920 of generating a motion probability image based on the generated motion detection image and motion detection images accumulated up to the previous frame.

[0173] 9 and 10, the control unit 200 may accumulate motion detection results in a separate memory in chronological order to generate a motion probability image 1020. The motion probability image 1020 may be used to determine an appropriate blending ratio of the previous frame image 820 and the current frame image 830 to generate an improved current frame image 840. As described above, the previous frame image 820 may include at least one frame. The current frame image 830 may include one frame.

[0174] The control unit 200 may perform the following process to perform step 920 of generating a motion probability image: The control unit 200 may perform a step of generating a motion probability image 1020 by combining a motion detection image 1010 of the current frame and one or more motion detection images up to previous frames.

[0175] More specifically, FIG. 11 illustrates a method for generating a motion probability image 1020 using a motion detection image 1010. The control unit 200 may generate and update the motion probability image 1020 by accumulating the motion detection image 1010 obtained through motion detection in a separate memory in time order for each frame. The image on the left side of FIG. 11 illustrates the accumulated and stored motion detection image 1110, and the image on the right side illustrates the motion probability image 1120 obtained by adding together the motion detection images. The motion probability image 1120 for the current frame may be generated by adding together the values ​​of the same pixel in the motion detection image 1010 for the previous frame and the motion detection image 1010 for the current frame. That is, the motion probability image 1120 for a particular frame is obtained by adding together the pixel values ​​of the same pixel in all motion detection images obtained up to that frame. For example, referring to FIG. 11, if the current frame is the fourth frame, the sum of the values ​​of the same pixel in the motion detection images obtained from the previous four frames is the value of the same pixel in the motion probability image for the current frame.

[0176] If a pixel determined to have motion in a motion-detected image is represented as bright with a value of "0" and a pixel determined to have no motion is represented as dark with a value of "1," each pixel of the motion probability image has a value corresponding to the sum of the motion detection values ​​(0 or 1) of the corresponding pixel and has a different value, i.e., different brightness, depending on the number of motion detections. For example, assuming a motion probability image consisting of 10 frames, the corresponding motion probability image is obtained by adding up the 10 motion-detected images, and each pixel of the motion probability image has one of the values ​​between 0 and 10. Here, if the same pixel in all the motion-detected images has a value of 0, the corresponding pixel in the motion probability image has a value of 0, and if the same pixel in all the motion-detected images has a value of 10, the corresponding pixel in the motion probability image has a value of 10. Therefore, as shown in FIG. 10, each pixel of the motion probability image has a pixel value, i.e., brightness, depending on the number of times motion is detected in the same pixel in the motion-detected images up to the corresponding frame.

[0177] In this sense, it can be determined that the brighter the pixel value in the generated motion probability image 1020, the higher the motion probability, and the darker the pixel value, the lower the motion probability. For example, if motion is detected at the same pixel position while frames progress in chronological order, the motion probability will be high, and if no motion is detected, the motion probability will be low.

[0178] The value of each pixel in the motion probability image 1020 indicates the degree of motion, or motion probability value, of the pixel. That is, if there is motion, a judgment value of "0" is assigned, and if there is no motion, a judgment value of "1" is assigned. The smaller the pixel value in the motion probability image 1020, the greater the motion probability of the pixel.

[0179] 12 illustrates an example of a process for generating a motion detection image 1010 and a motion probability image 1020 from an input image as frames progress. A motion detection image is generated by subtracting the frame image of each frame from the previous frame image, and the motion probability image 1020 can be generated by combining the motion detection image and the motion detection image of the previous frame.

[0180] Referring to FIG. 9, the control unit 200 may perform step 930 of generating an improved current frame image by blending the current frame image and the previous frame image based on the motion probability image.

[0181] To perform step 930 of generating an improved current frame image, the control unit 200 may perform a step of variably determining a blending ratio of the current frame image 830 and the previous frame image 820 according to a value indicating the degree of motion of each pixel of the motion probability image 1020. In addition, the control unit 200 may determine the blending ratio such that the greater the degree of motion indicated by the value of each pixel of the motion probability image 1020, the greater the reflection ratio of the current frame image compared to the previous frame image.

[0182] Here, the current frame image 830 may be a current frame image in a state in which noise has been reduced by the control unit 200, and the previous frame image 820 may be a previous frame image in which noise has been reduced by the control unit 200. Furthermore, the previous frame image 820 may be a frame image that has been improved in the past, or may be a frame image that has not been improved. In this case, the control unit 200 may generate an improved current frame image 840 by mixing the current frame image 830 and the previous frame image 820 at an appropriate mixing ratio based on the motion probability image 1020. That is, the control unit 200 may perform a weighted average of the current frame image 830 and the previous frame image 820 based on the motion probability image 1020.

[0183] The greater the degree to which the value of each pixel in the motion probability image 1020 indicates motion, the greater the reflection rate of the current frame image 830. That is, the blending rate can be determined so that the higher the motion probability determined by the pixel values ​​included in the motion probability image 1020, the higher the weight of the current frame image 830. For example, the reflection rate can be determined so that the greater the degree to which the pixel values ​​of the motion probability image 1020 indicate motion on a pixel-by-pixel basis, the greater the reflection rate of the current frame image 830 linearly increases.

[0184] As a specific example, for pixels with a lot of movement, a predetermined weight (α1), for example, 0.8, is assigned to the corresponding pixel of the current frame image 830, and a weight (1-α1), for example, 0.2, is assigned to the corresponding pixel of the previous frame image 820, and this blending process can be performed for all pixels.

[0185] Meanwhile, for pixels with little motion, a predetermined weight (α2), for example, 0.2, is assigned to the corresponding pixel of the current frame image 830, and a weight (1-α2), for example, 0.8, is assigned to the corresponding pixel of the previous frame image 820, so that the current frame image 830 and the previous frame image 820 can be blended. When the weight of the current frame image 830 is increased for pixels with a lot of motion, an image without motion blur can be obtained. As a result, the improved current frame image 840 is updated based on motion probability so that pixels with a lot of motion reflect more of the current frame value and pixels with little motion reflect more of the previous frame value, thereby improving noise reduction performance as frames accumulate over time.

[0186] The above description has focused on various embodiments. Those skilled in the art will understand that the present disclosure may be embodied in modified forms without departing from the essential characteristics of the present disclosure. Therefore, the disclosed embodiments should be considered from an illustrative rather than a restrictive perspective. The scope of the present disclosure is defined by the claims, not the above description, and all differences within the scope of the claims should be construed as being within the scope of the present disclosure.

[0187] Meanwhile, the above-described embodiments of the present disclosure can be created as a computer-executable program and can be implemented on a general-purpose digital computer that runs the program using a computer-readable recording medium, including storage media such as magnetic storage media (e.g., ROMs, floppy disks, hard disks, etc.) and optically readable media (e.g., CD-ROMs, DVDs, etc.).

Claims

1. In the radiation imaging device, an image output unit that outputs a first radiographic image included in a series of radiographic images acquired by radiographing the subject; an image brightness information extractor that acquires brightness information from the first radiation image; a first illumination condition calculation unit that determines a first illumination condition based on the brightness information; an irradiation control unit that controls a dose of radiation based on the first irradiation condition; a second irradiation condition calculation unit that determines a second irradiation condition based on a second radiographic image generated based on the first irradiation condition when the imaging region of the subject is fixed; a dose reduction unit that reduces or maintains the dose of radiation based on the second irradiation condition; deactivating the first irradiation condition calculation unit when the dose is reduced by the dose reduction unit; Deactivating the first irradiation condition calculation unit includes: the first irradiation condition calculation unit does not acquire the first irradiation condition, and the second irradiation condition calculation unit indicates that successive radiation images will be acquired based on the second irradiation condition determined.

2. 2. The radiographic imaging device according to claim 1, wherein a value obtained by subtracting a radiation dose based on the second irradiation condition from a radiation dose based on the first irradiation condition is equal to or smaller than 70% of the radiation dose based on the first irradiation condition.

3. A radiographic imaging device, an image output unit that outputs a first radiographic image included in a series of radiographic images acquired by radiographing the subject; an image brightness information extractor that acquires brightness information from the first radiation image; a first illumination condition calculation unit that determines a first illumination condition based on the brightness information; an irradiation control unit that controls a dose of radiation based on the first irradiation condition; a second irradiation condition calculation unit that determines a second irradiation condition based on a second radiographic image generated based on the first irradiation condition when the imaging region of the subject is fixed; a dose reduction unit that reduces or maintains the dose of radiation based on the second irradiation condition; generating an improved current frame image by accumulating and averaging pixel values ​​included in a current frame image included in a third radiation image output by the dose reduction unit and a previous frame image included in the third radiation image.

4. A radiographic imaging device, an image output unit that outputs a first radiographic image included in a series of radiographic images acquired by radiographing the subject; an image brightness information extractor that acquires brightness information from the first radiation image; a first illumination condition calculation unit that determines a first illumination condition based on the brightness information; an irradiation control unit that controls a dose of radiation based on the first irradiation condition; a second irradiation condition calculation unit that determines a second irradiation condition based on a second radiographic image generated based on the first irradiation condition when the imaging region of the subject is fixed; a dose reduction unit that reduces or maintains the dose of radiation based on the second irradiation condition; the radiation image capturing device further includes an image post-processing unit that performs post-processing on the third radiation image output at the reduced dose by the dose reducing unit; the image post-processing unit adjusts at least one of the brightness information and the contrast information of the third radiographic image so that the brightness information and the contrast information of the third radiographic image are similar to at least one of the brightness information and the contrast information of the second radiographic image.

5. a radiation irradiation unit that irradiates a subject with radiation; an image acquisition unit that receives radiation that has been irradiated from a radiation irradiation unit and passed through the subject, and generates successive radiation images; a control unit that controls the radiation irradiation unit and the image acquisition unit, the control unit acquiring brightness information based on a first radiation image included in the series of radiation images; determining a first illumination condition based on the brightness information by a first algorithm; controlling a dose of radiation based on the first irradiation condition; acquiring a second radiation image included in the series of radiation images and generated based on the first irradiation condition; acquiring motion information indicating whether the imaging region of the subject is fixed; determining a second irradiation condition based on the second radiation image by a second algorithm when the motion information indicates that the imaging region of the subject is fixed; controlling the dose of radiation based on the second irradiation condition; acquiring a third radiation image included in the series of radiation images and generated based on the second exposure condition; and acquiring the third radiation image, the third radiation image being acquired based on the pixel values ​​of at least a portion of a current frame image included in the third radiation image and the pixel values ​​of at least a portion of a previous frame image included in the third radiation image, thereby generating an improved current frame image.

6. The dose of radiation based on the second irradiation condition is the dose of radiation based on the first irradiation condition.

6. The method of claim 5, wherein the amount of radiation is greater than or equal to 30% of the amount of radiation.

7. The method of operating a radiographic imaging apparatus according to claim 5 , wherein the first algorithm for determining the first irradiation condition and the second algorithm for determining the second irradiation condition are different from each other.

8. A radiation irradiation unit that irradiates a subject with radiation; an image acquisition unit that receives radiation that has been irradiated from a radiation irradiation unit and passed through the subject, and generates successive radiation images; a control unit that controls the radiation irradiation unit and the image acquisition unit, the control unit acquiring brightness information based on a first radiation image included in the series of radiation images; determining a first illumination condition based on the brightness information by a first algorithm; controlling a dose of radiation based on the first irradiation condition; acquiring a second radiation image included in the series of radiation images and generated based on the first irradiation condition; acquiring motion information indicating whether the imaging region of the subject is fixed; determining a second irradiation condition based on the second radiation image by a second algorithm when the motion information indicates that the imaging region of the subject is fixed; controlling the dose of radiation based on the second irradiation condition; acquiring a third radiation image included in the series of radiation images and generated based on the second exposure condition; The step of acquiring the third radiological image comprises: generating a motion detecting image including motion detecting information for each pixel of a difference image obtained by subtracting a current frame image included in the third radiation image from a previous frame image included in the third radiation image; generating a motion probability image based on the generated motion detection image and motion detection images accumulated up to a previous frame; generating an improved current frame image by blending the current frame image and the previous frame image based on the motion probability image.

9. generating the motion probability image includes generating the motion probability image by summing one or more of the motion detection image of the current frame image and the motion detection images of the previous frames; generating the improved current frame image includes variably determining a mixing ratio of the current frame image and the previous frame image according to a value indicating a degree of motion of each pixel of the motion probability image; 9. The method of claim 8, wherein the mixing ratio is determined such that the greater the degree of motion indicated by the value of each pixel of the motion probability image, the greater the reflection ratio of the current frame image compared to the previous frame image.

10. A radiation irradiation unit that irradiates a subject with radiation; an image acquisition unit that receives radiation that has been irradiated from a radiation irradiation unit and passed through the subject, and generates successive radiation images; a control unit that controls the radiation irradiation unit and the image acquisition unit, the control unit acquiring brightness information based on a first radiation image included in the series of radiation images; determining a first illumination condition based on the brightness information by a first algorithm; controlling a dose of radiation based on the first irradiation condition; acquiring a second radiation image included in the series of radiation images and generated based on the first irradiation condition; acquiring motion information indicating whether the imaging region of the subject is fixed; determining a second irradiation condition based on the second radiation image by a second algorithm when the motion information indicates that the imaging region of the subject is fixed; controlling the dose of radiation based on the second irradiation condition; acquiring a third radiation image included in the series of radiation images and generated based on the second exposure condition; The step of obtaining the brightness information includes obtaining the brightness information by averaging pixel values ​​included in at least a portion of the first radiation image; The step of determining the first irradiation condition includes: If the brightness information is smaller than a predetermined first critical brightness information, determining the first illumination condition so that the brightness information is increased; and if the brightness information is greater than predetermined first critical brightness information, determining the first irradiation condition so that the brightness information becomes smaller.

11. The step of obtaining the brightness information by averaging pixel values ​​included in at least a portion of the first radiation image includes: acquiring a region in which the object appears from the first radiation image based on an object region acquisition model; 11. The method of claim 10, further comprising: obtaining the brightness information by averaging pixel values ​​included in the area where the object appears.

12. A radiation irradiation unit that irradiates a subject with radiation; an image acquisition unit that receives radiation that has been irradiated from a radiation irradiation unit and passed through the subject, and generates successive radiation images; a control unit that controls the radiation irradiation unit and the image acquisition unit, the control unit acquiring brightness information based on a first radiation image included in the series of radiation images; determining a first illumination condition based on the brightness information by a first algorithm; controlling a dose of radiation based on the first irradiation condition; acquiring a second radiation image included in the series of radiation images and generated based on the first irradiation condition; acquiring motion information indicating whether the imaging region of the subject is fixed; determining a second irradiation condition based on the second radiation image by a second algorithm when the motion information indicates that the imaging region of the subject is fixed; controlling the dose of radiation based on the second irradiation condition; acquiring a third radiation image included in the series of radiation images and generated based on the second exposure condition; The step of determining the second irradiation condition includes: downsampling the second radiation image in units of patches of a predetermined size to obtain a downsampled image; obtaining a minimum pixel value from among pixel values ​​included in the downsampled image; and if the minimum pixel value is greater than predetermined second critical brightness information, determining second irradiation conditions so that the minimum pixel value is equal to the second critical brightness information.

13. determining a second illumination condition so that the minimum pixel value is equal to the second critical brightness information; determining a reduction rate based on the minimum pixel value and the second critical brightness information; determining second irradiation conditions so that a dose obtained by subtracting a value obtained by multiplying the dose under the first irradiation conditions by the reduction rate from the dose under the first irradiation conditions is irradiated from the radiation irradiating unit; The method of operating a radiation image capturing apparatus according to claim 12, wherein the decrease rate is greater than 0 and less than a predetermined maximum decrease rate.

14. A radiation irradiation unit that irradiates a subject with radiation; an image acquisition unit that receives radiation that has been irradiated from a radiation irradiation unit and passed through the subject, and generates successive radiation images; a control unit that controls the radiation irradiation unit and the image acquisition unit, the control unit acquiring brightness information based on a first radiation image included in the series of radiation images; determining a first illumination condition based on the brightness information by a first algorithm; controlling a dose of radiation based on the first irradiation condition; acquiring a second radiation image included in the series of radiation images and generated based on the first irradiation condition; acquiring motion information indicating whether the imaging region of the subject is fixed; determining a second irradiation condition based on the second radiation image by a second algorithm when the motion information indicates that the imaging region of the subject is fixed; controlling the dose of radiation based on the second irradiation condition; acquiring a third radiation image included in the series of radiation images and generated based on the second exposure condition; The stage of acquiring motion information is as follows: determining the motion presence / absence information to indicate that the imaging region of the subject is not fixed when a time period during which at least one of the first radiation image and the second radiation image is acquired is less than a predetermined critical time period; determining the motion presence / absence information to indicate that the imaging region of the subject is fixed when a time period during which at least one of the first radiation image and the second radiation image was acquired is equal to or longer than a predetermined critical time period.

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