Dose management device, dose setting method, and dose setting program

Abstract

Set appropriate doses for dose management in dynamic imaging. [Solution] The dose management device includes a ratio acquisition unit that acquires the ratio of a first reference dose defined for when a first part of a subject is irradiated with radiation and captured as a still image, and a second reference dose defined for when the first part is irradiated with radiation and captured as a moving image, and a setting unit that sets a fourth reference dose for when the second part is captured as a moving image based on a third reference dose for when the second part is captured as a still image and the ratio.

Description

Technical Field

[0001] The present invention relates to a dose management apparatus, a dose setting method, and a dose setting program.

Background Art

[0002] In order to optimize the exposure dose of a patient, it is recommended to use a Diagnostic Reference Level (DRL). As the DRL, for example, an exposure dose (DRL value) for a patient with a standard body type is defined according to an examination modality, an examination region, and the like. In a dose management apparatus, dose management for radiographic image capturing is performed by comparing the exposure dose of the patient with the DRL value (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] In radiographic image capturing, in general radiography for capturing still images, dose management is performed by comparison with a DRL value as described above in order to optimize the exposure dose of a patient. Also in dynamic radiography for capturing a dynamic image having a plurality of frame images, it is desirable that dose management is performed similarly to general radiography in order to optimize the exposure dose of the patient. However, dynamic radiography is currently a new radiography technique that is transitioning from the stage of clinical research to the stage of being used in medical practice, and the method of dose management including setting of DRL values has not been established.

[0005] An object of the present invention is to provide a dose management apparatus, a dose setting method, and a dose setting program capable of setting an appropriate dose for dose management in dynamic radiography.

Means for Solving the Problems

[0006] The dose control device according to the present invention is A ratio acquisition unit that acquires the ratio of a first reference dose specified for when a first part of a subject is irradiated with radiation and a still image is taken of that part, and a second reference dose specified for when the first part is irradiated with radiation and a dynamic image is taken of that part, A setting unit sets a fourth reference dose for when the second part is captured in motion, based on a third reference dose for when the second part is captured in still images and the ratio, It is equipped with.

[0007] The dose setting method according to the present invention is In a dose control device, The ratio of a first reference dose specified for the case where a first part of the subject is irradiated with radiation and a still image is taken, to a second reference dose specified for the case where the first part is irradiated with radiation and a dynamic image is taken, is determined. A third reference value for the dose when the second part is captured as a still image, and the ratio, are used to set a fourth reference value for the dose when the second part is captured as a moving image.

[0008] The dose setting program according to the present invention is The computer in the dose management device, A process to determine the ratio between a first reference dose specified for the case in which a first part of a subject is irradiated with radiation and a still image is taken, and a second reference dose specified for the case in which the first part is irradiated with radiation and a dynamic image is taken. A process to set a fourth reference dose for when the second part is captured in motion, based on a third reference dose for when the second part is captured in still images and the ratio, Make it run. [Effects of the Invention]

[0009] According to the present invention, it is possible to set an appropriate dose for dose management in dynamic imaging. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is an explanatory diagram illustrating an example of the configuration of a radiation image processing system according to an embodiment of the present invention. [Figure 2] Figure 2 is a block diagram illustrating an example of the functional configuration of the imaging control unit in a radiation imaging system that constitutes a radiation image processing system. [Figure 3] Figure 3 is a block diagram illustrating an example of the functional configuration of a radiography control device that constitutes a radiographic image processing system. [Figure 4] Figure 4 is a block diagram illustrating an example of the functional configuration of a radiation image analysis device that constitutes a radiation image processing system. [Figure 5] Figure 5 is a block diagram illustrating an example of the functional configuration of a dose control device that constitutes a radiation image processing system. [Figure 6] Figure 6 illustrates the DRL value (incident surface dose) for dynamic radiography, which is set based on the DRL value (incident surface dose) for general radiography, in the dose management device shown in Figure 5. [Figure 7] Figure 7 illustrates the DRL value (incident surface dose) for dynamic radiography, which is set based on the DRL value (incident surface dose) set by the facility for general radiography, in the dose control device shown in Figure 5. [Figure 8] Figure 8 is a graph displayed for comparison in the dose management device shown in Figure 5, comparing the DRL values ​​shown in Figures 6 and 7 with the patient's radiation dose. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0012] <Configuration of the Radiation Image Processing System> Figure 1 is a diagram for explaining the radiation image processing system 100 of the present embodiment. The radiation image processing system 100 includes a radiation image capturing system 10, a radiation capturing control apparatus (console apparatus) 20, a radiation image analysis apparatus 30, an image management apparatus 40, a client terminal 50, a dose management apparatus 60, and a modality 70.

[0013] In the example shown in Figure 1, the radiation image capturing system 10 is arranged in an imaging room, and the radiation capturing control apparatus 20 is arranged in an operation room. Note that the radiation image capturing system 10 and the radiation capturing control apparatus 20 may be configured to be mounted on a movable cart such as a rounds vehicle, for example.

[0014] The radiation image capturing system 10, the radiation capturing control apparatus 20, the radiation image analysis apparatus 30, the image management apparatus 40, the client terminal 50, and the dose management apparatus 60 are connected to one another via a communication network N. As the communication network N, for example, a communication network conforming to the DICOM (Digital Image and Communications in Medicine) standard or the like is used.

[0015] Further, a modality 70 including radiation image capturing apparatuses other than the radiation image capturing system 10 and the radiation capturing control apparatus 20 illustrated in Figure 1 is also connected to the communication network N. The modality 70 includes an X-ray CT (Computed Tomography) apparatus that captures tomographic images, a general X-ray imaging apparatus that captures still images, and the like. In the present embodiment, the radiation image capturing subject to dose management is dynamic imaging performed by the radiation image capturing system 10 and the radiation capturing control apparatus 20 illustrated in Figure 1.

[0016] Although not illustrated, a radiation information terminal serving as a radiation information system that transmits information related to radiological examinations, such as patient examination order information, to the radiation image processing system 100 is connected to the communication network N. Examples of the radiation information terminal include RIS (Radiology Information System) and the like.

[0017] The radiation image capturing system 10 performs radiation dynamic image capturing (hereinafter referred to as dynamic image capturing), which is capturing of a radiation dynamic image (hereinafter referred to as dynamic image), under the control of the radiation capturing control device 20. The radiation capturing control device 20 controls the radiation image capturing system 10 based on examination order information and the like transmitted from a radiation information terminal. The dynamic image generated by the radiation image capturing system 10 is processed by the radiation capturing control device 20 and then transmitted to the radiation image analysis device 30. The radiation image analysis device 30 executes dynamic analysis on the dynamic image. The dynamic image and the result of the dynamic analysis are transmitted to and managed by the image management device 40 serving as a medical image management system. Examples of the image management device 40 include PACS (Picture Archiving and Communication System) and the like. The dynamic image and the result of the dynamic analysis are transmitted to the client terminal 50 and viewed by medical personnel such as doctors.

[0018] In the present embodiment, dynamic image capturing refers to obtaining a moving image composed of a plurality of frame images by repeatedly irradiating a subject with pulsed radiation (for example, X-rays) at a predetermined frame rate (pulse irradiation). Further, the dynamic image refers to a moving image composed of a series of frame images obtained by dynamic image capturing. Further, the dynamic analysis refers to an analysis process performed on a dynamic image, and includes not only a process of analyzing the movement of a subject based on the dynamic image, but also a process of analyzing the dynamic image to emphasize or attenuate (remove) a predetermined structure.

[0019] Each of the radiation image capturing system 10, the radiation capturing control device 20, and the radiation image analysis device 30 is a type of computer that has a processor and a memory, and implements predetermined functions by reading, developing, and executing a program stored in the memory.

[0020] [Radiation Image Capturing System] As shown in Figure 1, the radiation imaging system 10 comprises an imaging control unit 11, a radiation irradiation unit 12, an imaging table 13, a radiation detection unit 14, a display unit 15, and an audio output unit 16.

[0021] The imaging control unit 11 acquires setting information regarding dynamic imaging settings from the radiation imaging control device 20. Based on the setting information, the imaging control unit 11 sets the imaging conditions for dynamic imaging, controls the radiation irradiation unit 12 based on those imaging conditions, irradiates the patient M (subject) with radiation, and performs imaging. The imaging control unit 11 is composed of a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), etc.

[0022] The setting information refers to information regarding the settings for performing dynamic imaging on patient M. For example, the setting information includes at least one of several types of dynamic analysis that the radiographic image analysis device 30 can perform on the dynamic images. If multiple types of dynamic analysis are combined, the setting information may also include information regarding that combination. The setting information is set in the radiographic imaging control device 20 (described later) by the operator of the radiographic image processing system 100, such as a radiographer.

[0023] The imaging conditions include, for example, conditions related to patient M, such as the imaging area, imaging direction, patient M's position, patient M's build, patient M's condition, patient M's age, and patient M's sex. The imaging area is, for example, the chest, legs, etc. Patient M's build may be specified by numerical values ​​such as patient M's weight, height, BMI (Body Mass Index), body thickness, etc., or by categories such as large, medium, small, thin, average, overweight, etc. Patient M's condition includes types of breathing such as breath-holding and deep breathing. Patient M's age may be specified by numerical values ​​or by categories such as child, adult, etc. Patient M's sex may be identified by physical structural characteristics.

[0024] Furthermore, the imaging conditions also include conditions related to radiation irradiation, such as the type of examination, tube voltage, tube current, imaging time, current-time product, distance, pulse rate, pulse width, pulse interval, number of frames per imaging, and dose per unit time during radiation irradiation. Distance is the distance from the radiation irradiation unit 12 (radiation source) to the radiation detection unit 14 (Focus Film Distance: FFD, or Source Image receptor Distance: SID). The pulse rate is the number of radiation irradiations per second and corresponds to the frame rate of the image data. The pulse width is the radiation irradiation time per radiation irradiation. The pulse interval is the time from the start of one radiation irradiation to the start of the next radiation irradiation and corresponds to the temporal interval (frame interval) between multiple image data.

[0025] These shooting conditions can be automatically determined by the shooting control unit 11 of the radiation imaging system 10 based on the setting information.

[0026] The radiation irradiation unit 12 is positioned opposite the radiation detection unit 14, which is fixed to the imaging table 13. The radiation irradiation unit 12 irradiates radiation according to the operation of the irradiation instruction switch 11a connected to the imaging control unit 11.

[0027] Specifically, the radiation irradiation unit 12 applies a voltage to the radiation source (tube) according to the preset imaging conditions based on the operation of the irradiation instruction switch 11a, and generates radiation (e.g., X-rays) in a dose corresponding to the applied voltage.

[0028] The radiation irradiation unit 12 generates radiation in a manner corresponding to the radiation image to be generated (still image, motion image, etc.). For example, in the case of a still image, radiation is irradiated only once for each press of the irradiation instruction switch 11a. In the case of a motion image, pulsed radiation is continuously irradiated from the time the irradiation instruction switch 11a is pressed (instruction to start shooting) until it is released (instruction to end shooting).

[0029] The radiation detection unit 14 is composed of a semiconductor image sensor such as an FPD (Flat Panel Detector) and generates digital data of the radiation image. The radiation detection unit 14 has a substrate in which a plurality of detection elements (pixels) are arranged in a matrix, and each pixel on the substrate detects the incident radiation and converts it into an electrical signal corresponding to the intensity of the detected radiation and stores it. Each pixel on the substrate is composed of a switching unit such as a TFT (Thin Film Transistor).

[0030] The radiation detection unit 14 controls the switching unit of each pixel based on the image reading conditions input from the radiation imaging control device 20 to read the electrical signal accumulated in each pixel and outputs intensity information for each pixel to the image generation unit 113. The image reading conditions include, for example, the frame rate, frame interval, pixel size, and image size (matrix size). The frame rate is the number of frame images acquired per second and is the same as the pulse rate. The frame interval is the time from the start of one image data acquisition operation to the start of the next frame image acquisition operation and is the same as the pulse interval.

[0031] The imaging control unit 11 and the radiation detection unit 14 are connected to each other and exchange synchronization signals to synchronize the radiation irradiation operation and the image reading operation.

[0032] In this way, the radiation imaging system 10 performs dynamic imaging of radiation images by having the radiation irradiation unit 12 irradiate radiation under the control of the imaging control unit 11, and generating image data based on the radiation intensity detected by the radiation detection unit 14.

[0033] The display unit 15 and the audio output unit 16 provide instructions to patient M regarding the posture to be taken (shooting position), physical condition, respiratory condition, etc., when performing dynamic imaging of patient M. The display unit 15 is, for example, a display device such as a CRT (Cathode Ray Tube), liquid crystal display (Liquid Crystal Display), or organic EL (Electro Luminescence) display. The audio output unit 16 is, for example, an audio output device such as a speaker. The audio output unit 16 provides instructions to patient M regarding physical condition, respiratory condition, etc., for example, by auto-voice. The display unit 15 and the audio output unit 16 may each provide the same instructions to patient M, or only one of them may provide instructions.

[0034] Figure 2 is a block diagram illustrating an example of the functional configuration of the imaging control unit 11 in the radiation image acquisition system 10, which constitutes the radiation image processing system 100. The imaging control unit 11 includes a setting information acquisition unit 111, an imaging condition determination unit 112, an image generation unit 113, and a storage unit 114.

[0035] The setting information acquisition unit 111 acquires setting information from the radiation imaging control device 20.

[0036] The imaging condition determination unit 112 determines the imaging conditions for performing dynamic imaging of patient M based on the setting information. Information showing the correspondence between multiple types of dynamic analysis and imaging conditions suitable for each dynamic analysis is stored in advance in the storage unit 114. In addition, information showing the correspondence between combinations of multiple types of dynamic analysis and imaging conditions suitable for those combinations is also stored in advance in the storage unit 114. The imaging condition determination unit 112 simply needs to read the information showing the correspondence from the storage unit 114 for the dynamic analysis or combination of multiple types of dynamic analysis indicated by the setting information, and compare it with the setting information to determine the imaging conditions.

[0037] In addition, in cases such as screening or emergency situations, it may not be possible to set the dynamic analysis information. In such cases, the imaging condition determination unit 112 determines the imaging conditions by having the operator select at least one imaging condition from a plurality of predefined imaging conditions. The imaging condition determination unit 112 also has the operator select examination order information and determines the imaging conditions based on the selected examination order information. Thus, if dynamic analysis cannot be set before dynamic imaging, dynamic analysis is set after dynamic imaging with the imaging conditions selected by the operator, and the dynamic analysis is performed by the radiographic image analysis device 30.

[0038] The image generation unit 113 performs dynamic imaging of patient M based on the determined imaging conditions and generates multiple frames of radiographic images. Specifically, the image generation unit 113 controls the operation of the radiation irradiation unit 12 and the radiation detection unit 14 based on the imaging conditions, and generates image data by acquiring intensity information regarding the radiation intensity transmitted through the subject from the radiation detection unit 14 for each pixel.

[0039] As described above, the memory unit 114 pre-stores information showing the correspondence between multiple types of motion analysis and shooting conditions suitable for each motion analysis, as well as information showing the correspondence between combinations of multiple types of motion analysis and shooting conditions suitable for those combinations.

[0040] [Radiography control device] The radiography control device 20 is, for example, a computer such as a PC (Personal Computer) or workstation. The radiography control device 20 may be a desktop computer, as shown in the example in Figure 1, or it may be a portable computer, such as a laptop computer or a tablet computer.

[0041] The radiography control device 20 receives inspection order information from the radiography information terminal and transmits it to the radiography imaging system 10, thereby controlling the dynamic imaging of the radiography imaging system 10.

[0042] The examination order information includes various information related to the dynamic imaging to be performed next, such as instructions regarding respiration, patient information, examination information, imaging information, and data attributes. The examination information includes information such as the examination ID, target area (e.g., chest, abdomen, lungs, heart, etc.), and type of analysis (e.g., ventilation analysis, pulmonary blood flow analysis, measurement of maximum ventilation, etc.). The examination order information is generated, for example, when a doctor requests dynamic imaging of patient M from the radiographic image processing system 100.

[0043] Furthermore, the radiography control device 20 generates setting information indicating at least one of several types of dynamic analysis that the radiography image analysis device 30 can perform, based on the operator's input. When combining multiple types of dynamic analysis, the radiography control device 20 generates setting information indicating the combination of multiple types of dynamic analysis. The operator recognizes which of the multiple types of dynamic analysis to combine by, for example, referring to the contents of the examination order information, and performs an input operation to generate the setting information based on this. Alternatively, the operator may recognize which dynamic analysis to combine based on information conveyed by a physician or other person through another method.

[0044] Figure 3 is a block diagram illustrating an example of the functional configuration of a radiography control device 20 that constitutes a radiographic image processing system 100. The radiography control device 20 includes a control unit 21, a storage unit 22, an operation unit 23, a display unit 24, and a communication unit 25. Each component of the radiography control device 20 is connected to the others by a bus 26.

[0045] The radiography control device 20 outputs setting conditions set by the operator and other personnel, as well as inspection order information acquired in advance from the radiography information terminal, to the radiography imaging system 10, and controls the imaging process performed by the radiography imaging system 10. The radiography control device 20 may also display the dynamic images generated by the radiography imaging system 10, for example, for the operator to review.

[0046] The control unit 21 is composed of a CPU and RAM, etc. In the control unit 21, the CPU reads system programs and various processing programs stored in the memory unit 22 in response to the operation of the operation unit 23, loads them into the RAM, and controls the operation of each part of the radiography control device 20 based on the loaded programs.

[0047] The storage unit 22 is composed of non-volatile semiconductor memory, a hard disk, or the like. The storage unit 22 stores various programs executed by the control unit 21, parameters necessary for processing by the programs, or data such as processing results (dynamic images, etc.). The various programs are stored in the form of readable program code, and the control unit 21 sequentially executes operations according to the program code.

[0048] Furthermore, the memory unit 22 stores the image reading conditions for performing dynamic imaging. In addition, the memory unit 22 stores the examination order information transmitted from the radiation information terminal. When the radiation imaging control device 20 controls the dynamic imaging of the radiation imaging system 10, it reads the image reading conditions and examination order information corresponding to patient M from the memory unit 22 and transmits them.

[0049] The operation unit 23 is an operating device such as a keyboard equipped with cursor keys, number input keys, and various function keys, a pointing device such as a mouse or trackball, and a touch panel. The operation unit 23 generates instruction signals based on the operator's input and outputs them to the control unit 21.

[0050] The display unit 24 is composed of display devices such as a CRT, liquid crystal display, or organic EL display. The display unit 24 displays input instructions from the operation unit 23 and image data (such as motion images) generated by the radiation imaging system 10, in accordance with the instructions of the display signals input from the control unit 21.

[0051] The communication unit 25 transmits and receives data between the radiation image acquisition system 10, the radiation image analysis device 30, and the like.

[0052] [Radiation Image Analysis Equipment] The radiation image analysis device 30 is, for example, a computer such as a PC or workstation. The radiation image analysis device 30 may be a desktop computer or a portable computer, such as a laptop computer or a tablet computer.

[0053] The radiation image analysis device 30 performs motion analysis on motion images captured by the radiation image acquisition system 10 based on the setting information set in the radiation imaging control device 20.

[0054] Figure 4 is a block diagram illustrating an example of the functional configuration of a radiation image analysis device 30 that constitutes a radiation image processing system 100. The radiation image analysis device 30 includes a control unit 31, a storage unit 32, an operation unit 33, a display unit 34, and a communication unit 35. Each component of the radiation image analysis device 30 is connected by a bus 36.

[0055] The control unit 31 is composed of a CPU and RAM, etc. In the control unit 31, the CPU reads system programs and various processing programs stored in the memory unit 32 in response to the operation of the operation unit 33, expands them into RAM, and performs operational control and dynamic analysis of each part of the radiation image analysis device 30 based on the expanded programs.

[0056] The control unit 31 acquires dynamic images, which are multiple frames of radiographic images generated by the radiographic imaging system 10 and the radiographic imaging control device 20, and performs dynamic analysis on the dynamic images as set in the configuration information, and obtains the analysis results. For example, the control unit 31 performs the analysis based on signal changes in the multiple frame images.

[0057] The control unit 31 has various types of dynamic analysis, such as blood flow analysis mode, ventilation analysis mode, adhesion analysis mode, diaphragm displacement analysis mode, and orthopedic-related measurement mode. Each mode is briefly described below.

[0058] The blood flow analysis mode visualizes signal changes within the lung field that are synchronized with the heartbeat.

[0059] The ventilation analysis mode extracts temporal signal changes in a specific time-frequency band and visualizes the behavior of lung tissue during respiration.

[0060] Adhesion analysis mode is a mode that visualizes the degree of adhesion in tissues.

[0061] The diaphragm displacement analysis mode tracks the vertical movement of the diaphragm during respiration.

[0062] The orthopedic measurement mode measures the positional changes of specified bones, such as in the limbs, and displays the trajectory of their movement.

[0063] The storage unit 32 is composed of non-volatile semiconductor memory, a hard disk, or the like. The storage unit 32 stores various programs executed by the control unit 31, parameters necessary for processing by those programs, or data such as processing results (dynamic images, analysis results, etc.). The various programs are stored in the form of readable program code, and the control unit 31 sequentially executes operations according to the program code.

[0064] Furthermore, the memory unit 32 stores patient information, examination information, and list information indicating the status (for example, progress status such as receiving, dynamic analysis in progress, analysis completed, etc.) related to each dynamic image generated by the radiographic imaging system 10.

[0065] The operation unit 33 is an operating device such as a keyboard equipped with cursor keys, numeric input keys, and various function keys, a pointing device such as a mouse or trackball, and a touch panel. The operation unit 33 generates instruction signals based on the operator's input and outputs them to the control unit 31. The operation unit 33 may also be equipped with a touch panel on the display screen of the display unit 34, in which case it outputs instruction signals input via the touch panel to the control unit 31.

[0066] The display unit 34 is composed of display devices such as a CRT, liquid crystal display, or organic EL display. The display unit 34 displays input instructions from the operation unit 33 and data generated by the radiation imaging system 10 (dynamic images, analysis results, etc.) according to the instructions of the display signals input from the control unit 31.

[0067] The communication unit 35 transmits and receives data between the radiography control device 20 and the image management device 40, etc.

[0068] [Image management device, client terminal] The image management device 40 and client terminal 50 are, for example, computers such as PCs and workstations. The image management device 40 and client terminal 50 may be desktop computers or portable computers, such as laptop computers or tablet computers. Since the image management device 40 and client terminal 50 may be well-known image management devices and client terminals, a detailed explanation is omitted here.

[0069] [Dose control device] The dose management device 60 is also a computer, such as a PC or workstation. The dose management device 60 may be a desktop computer or a portable computer, such as a laptop computer or a tablet computer.

[0070] The dose management device 60 records and manages dose information related to radiation doses associated with the acquisition of still and dynamic radiographic images. Specifically, the dose management device 60 has a recording function for recording dose information and a management function for managing dose information. The recording function records and stores information, including dose information associated with the acquisition of radiographic images, for each individual patient. The management function manages dose information by comparing the stored dose information for each individual patient with a set diagnostic reference level.

[0071] While diagnostic reference levels are defined for general radiography, depending on the area being examined, there are no defined diagnostic reference levels for dynamic radiography, which captures moving images, making dose management difficult.

[0072] Therefore, in this embodiment, the dose management device 60 is further equipped with a setting function (ratio acquisition unit 611, setting unit 612, and correction unit 613) for setting a diagnostic reference level for a dynamic image acquisition device for which no diagnostic reference level has been set. The setting function (ratio acquisition unit 611, setting unit 612, and correction unit 613) will be described below with reference to Figure 5.

[0073] Figure 5 is a block diagram illustrating an example of the functional configuration of a dose management device 60 that constitutes a radiation image processing system 100. The dose management device 60 includes a control unit 61, a storage unit 62, an operation unit 63, a display unit 64, and a communication unit 65. Each component of the dose management device 60 is connected by a bus 66.

[0074] The control unit 61 is composed of a CPU and RAM, etc. In the control unit 61, the CPU reads system programs and various processing programs stored in the memory unit 62 in response to the operation of the operation unit 63, expands them into RAM, and performs operation control and dose management of each part of the dose management device 60 based on the expanded programs.

[0075] The control unit 61 includes a ratio acquisition unit 611, a setting unit 612, and a correction unit 613. The first diagnostic reference levels L1 to L5 in the following are examples of the first to fifth reference values, respectively.

[0076] The ratio acquisition unit 611 reads, for example, the first diagnostic reference level L1 and the second diagnostic reference level L2 stored in the memory unit 62. The first diagnostic reference level L1 is a diagnostic reference level for the dose specified when a predetermined part of a subject (an example of a first part) is irradiated with radiation and a still image is taken. The second diagnostic reference level L2 is a diagnostic reference level for the dose specified when a predetermined part is irradiated with radiation and a dynamic image is taken. The ratio acquisition unit 611 then acquires the ratio R = L2 / L1.

[0077] Furthermore, the ratio acquisition unit 611 may use the fifth diagnostic reference level L5 instead of the first diagnostic reference level L1 to determine the ratio R = L2 / L5. The fifth diagnostic reference level L5 is a diagnostic reference level for the dose specified when a predetermined part of a subject is irradiated with radiation and a still image is taken, and is a diagnostic reference level specified by the imaging facility itself.

[0078] The setting unit 612 reads, for example, the third diagnostic reference level L3 stored in the memory unit 62. The third diagnostic reference level L3 is the diagnostic reference level for the dose when a target area different from the predetermined area (an example being the second area) is photographed as a still image. Then, based on the third diagnostic reference level L3 and the ratio R, the setting unit 612 sets the fourth diagnostic reference level L4, which is the dose used for dose management when photographing the target area as a dynamic image. Specifically, the fourth diagnostic reference level L4 = L3 × R. Here, the target area is a different area from the predetermined area, but it may also be the same area as the predetermined area.

[0079] The correction unit 613 corrects the fourth diagnostic reference level L4 according to the target area (for example, the thickness of the target area). In addition, if the target area is the chest, the correction unit 613 may correct the fourth diagnostic reference level L4 according to the respiratory status of the subject.

[0080] The storage unit 62 is composed of non-volatile semiconductor memory, a hard disk, or the like. The storage unit 62 stores various programs executed by the control unit 61 (for example, a dose setting program that executes a dose setting method) and parameters necessary for processing by the program. The various programs are stored in the form of readable program code, and the control unit 61 sequentially executes operations according to the program code.

[0081] Furthermore, the memory unit 62 stores dose information of the radiation dose at the time of imaging in still images and motion images received from the radiography control device 20. For example, the memory unit 62 stores still images and motion images received from the radiography control device 20 in association with the corresponding dose information. The memory unit 62 may also store dose information of the radiation dose to which the patient was exposed in ways other than the imaging of still images and motion images.

[0082] The memory unit 62 also stores the first diagnostic reference level L1 to the fifth diagnostic reference level L5, the ratio R, etc. The first diagnostic reference level L1 is, for example, the diagnostic reference level (DRL value) for each examination item of general radiography as defined in DRLs2020 (for example, items such as the imaging site and the age of the patient being examined).

[0083] The operation unit 63 is an operating device such as a keyboard equipped with cursor keys, numeric input keys, and various function keys, a pointing device such as a mouse or trackball, and a touch panel. The operation unit 63 generates instruction signals based on the operator's input and outputs them to the control unit 61. The operation unit 63 may also be equipped with a touch panel on the display screen of the display unit 64, in which case it outputs instruction signals input via the touch panel to the control unit 61.

[0084] The display unit 64 is composed of a display device such as a CRT, liquid crystal display, or organic EL display. The display unit 64 displays input instructions from the operation unit 63 and data from the dose management device 60, etc., according to the instructions of the display signals input from the control unit 61.

[0085] The communication unit 65 transmits and receives data between the radiography control device 20 and the image management device 40, etc.

[0086] In the example shown in Figure 1, the dose control device 60 is a separate device from the radiation imaging control device 20 and the image management device 40, but it does not have to be a separate device and may be included in the radiation imaging control device 20, the image management device 40, etc.

[0087] [Method for setting dose] (Example setting 1) The method for setting a diagnostic reference level for dynamic radiography, for which no diagnostic reference level has been set in the dose management device 60, will be explained with reference to Figure 6. Figure 6 is a diagram illustrating the DRL value (incident surface dose) for dynamic radiography, which is set based on the DRL value (incident surface dose) for general radiography, in the dose management device 60 shown in Figure 5. Here, the incident surface dose is used as the DRL value, so the explanation will be given using the incident surface dose as an example, but other doses may be used as the DRL value, for example, area dose (DAP: Dose-Area Product).

[0088] As shown in Figure 6, for general radiography, the incident surface dose listed in each column from "Frontal chest (less than 100kV)" to "Frontal pelvis" is defined as the DRL value.

[0089] In general radiography, the incident surface dose for the front of the chest (100kV or higher) is set at 0.3mGy as the DRL value (first diagnostic reference level L1). Furthermore, in dynamic radiography using a radiographic imaging system 10 and radiographic imaging control device 20 installed in a certain facility, the incident surface dose for the front of the chest (100kV or higher) is set at 0.45mGy as the DRL value (second diagnostic reference level L2). In this case, the ratio acquisition unit 611 of the control unit 61 calculates the ratio R = L2 / L1. In this example, the ratio R = 1.5.

[0090] Then, the setting unit 612 of the control unit 61 uses the ratio R to set the DRL value for each field in dynamic imaging (4th diagnostic reference level L4) by multiplying the DRL value for each field (3rd diagnostic reference level L3) specified for general radiography by the ratio R. For example, for "frontal chest (less than 100kV)", the DRL value for general radiography is "0.4mGy", so multiplying by the ratio R=1.5 results in a DRL value for dynamic imaging of "0.6mGy".

[0091] As described above, the control unit 61 sets a fourth diagnostic reference level L4, which is the diagnostic reference level, for dynamic imaging for which no diagnostic reference level has been set.

[0092] As described above, the dose management device 60 comprises a ratio acquisition unit 611 and a setting unit 612. Here, the first diagnostic reference level L1 is the dose set for when a predetermined part of the subject is irradiated with radiation and a still image is taken (general radiography), and the second diagnostic reference level L2 is the dose set for when a predetermined part is irradiated with radiation and a dynamic image is taken (dynamic radiography). The ratio acquisition unit 611 acquires the ratio R = L2 / L1 of the first diagnostic reference level L1 and the second diagnostic reference level L2. The setting unit 612 sets the fourth diagnostic reference level L4 for the dose when the target part is irradiated with radiation and a dynamic image is taken, based on the third diagnostic reference level L3 for the dose when the target part is irradiated with radiation and the ratio R set by the ratio acquisition unit. Specifically, the setting unit 612 sets the fourth diagnostic reference level L4 for the dose used for dose management when the target part is irradiated with dynamic image by multiplying the third diagnostic reference level L3 by the ratio R.

[0093] Since the dose management device 60 has the configuration described above, it is possible to set an appropriate diagnostic reference level for dose management in dynamic imaging.

[0094] (Example setting 2) In the example shown in Figure 6, the prescribed DRL value (first diagnostic reference level L1) is used directly for general radiography. However, some radiography facilities do not use the prescribed DRL value (first diagnostic reference level L1) for general radiography, but instead use their own DRL value (fifth diagnostic reference level L5).

[0095] In this case, when setting a diagnostic reference level for dynamic radiography where no diagnostic reference level has been set, the facility's own DRL value (5th diagnostic reference level L5) is used instead of the DRL value (1st diagnostic reference level L1) specified for general radiography. In this case, the method for setting a diagnostic reference level for dynamic radiography where no diagnostic reference level has been set will be explained with reference to Figure 7. Figure 7 is a diagram illustrating the DRL value (incident surface dose) for dynamic radiography set in the dose control device 60 shown in Figure 5, based on the DRL value (incident surface dose) set by the facility for general radiography.

[0096] This example setting is basically the same as Example Setting 1 above. Here, in general radiography, the incident surface dose for "frontal chest (100kV or higher)" is set to "0.2mGy," which is unique to the radiography facility, as the DRL value (5th diagnostic reference level L5). Furthermore, in dynamic radiography using the radiography imaging system 10 and radiography control device 20 installed in the facility, the incident surface dose for "frontal chest (100kV or higher)" is set to "0.30mGy," which is the DRL value (2nd diagnostic reference level L2). In this case, the ratio acquisition unit 611 of the control unit 61 calculates the ratio R = L2 / L5. In this example, the ratio R = 1.5.

[0097] Then, the setting unit 612 of the control unit 61 uses a ratio R=1.5 to set the DRL value for each field in dynamic imaging (4th diagnostic reference level L4) by multiplying the DRL value for each field (5th diagnostic reference level L5) set for general radiography by the ratio R=1.5. For example, for "frontal chest (less than 100kV)", the DRL value for general radiography is "0.3mGy", so multiplying by the ratio R=1.5 results in a DRL value of "0.45mGy" for the radiography imaging device.

[0098] As described above, the control unit 61 sets a fourth diagnostic reference level L4, which is the diagnostic reference level, for dynamic imaging for which no diagnostic reference level has been set.

[0099] The dose management device 60 then manages the patient's dose information using the diagnostic reference level set as described above.

[0100] Specifically, when the radiographic imaging system 10 and the radiographic imaging control device 20 capture still or moving images, the control unit 21 of the radiographic imaging control device 20 calculates the incident surface dose at the time of imaging based on the actual imaging conditions, which are the imaging execution conditions. For example, the control unit 21 calculates the incident surface dose at the time of imaging based on the imaging execution conditions, such as the type of examination, FFD (or SID), tube voltage, current-time product, frame rate, imaging time, patient's position, patient's physique, patient's condition, patient's age, patient's gender, etc.

[0101] The control unit 21 of the radiation imaging control device 20 transmits the imaging conditions, incident surface dose, etc., in association with the captured still and moving images, to the radiation image analysis device 30, image management device 40, dose management device 60, etc., via the communication unit 25. The dose management device 60 may also acquire the imaging conditions, incident surface dose, etc., along with the still and moving images, from the radiation imaging control device 20, image management device 40, etc., depending on its operation.

[0102] The control unit 61 of the dose management device 60 stores and accumulates transmitted or acquired still images, dynamic images, shooting conditions, incident surface dose, etc., in the storage unit 62, and displays information comparing the set diagnostic reference level with the incident surface dose for patients subject to dose management on the display unit 24.

[0103] Here, Figure 8 is a graph displayed for comparison in the dose management device 60 shown in Figure 5, and it compares the DRL values ​​shown in Figures 6 and 7 with the patient's radiation dose.

[0104] In this way, the control unit 61 provides dose management information to the operator of the dose management device 60 by displaying a graph on the display unit 24 that compares the set diagnostic reference level with the exposure dose for patients subject to dose management. The control unit 61 may also provide the operator of the dose management device 60 with information to review the currently set diagnostic reference level by, for example, displaying the exposure doses of multiple patients for each examination item in a histogram. Furthermore, the control unit 61 may calculate the number of still and dynamic images (frames) and the shooting time that are permissible thereafter based on the set diagnostic reference level and the patient's exposure dose, and provide the calculated results to the radiography control device 20.

[0105] (Example setting 3) In the above setting examples 1 and 2, the influence of each body part is not taken into consideration, but you may set the diagnostic reference level while taking the influence of each body part into consideration.

[0106] For example, in the chest, the amount of radiation transmitted varies depending on the breathing state, so it is better to adjust the diagnostic reference level according to the breathing state. Specifically, since the amount of radiation transmitted increases when taking an X-ray while inhaling compared to when exhaling, the diagnostic reference level can be set lower. For example, in a chest X-ray taken during a health checkup, the image is taken while inhaling, so the diagnostic reference level can be set lower.

[0107] In this example configuration, the control unit 61 has a correction unit 613, which corrects the DRL value (4th diagnostic reference level L4) for frontal chest imaging while the patient is inhaling, using a correction coefficient α. In this case, the correction coefficient α is, for example, 0.9. In this case, for "frontal chest imaging (100kV or higher)" shown in Figure 6, the DRL value (4th diagnostic reference level L4) for dynamic imaging is "0.30", so this is multiplied by the correction coefficient α = 0.9 to set "0.27" as the corrected DRL value.

[0108] Furthermore, since the amount of X-ray transmission also changes with body thickness, the DRL value (4th diagnostic reference level L4) may be corrected according to the body thickness. For example, since the lateral aspect of the lumbar spine is thicker than other areas, the correction unit 613 of the control unit 61 corrects the DRL value (4th diagnostic reference level L4) for imaging of the lateral aspect of the lumbar spine using a correction coefficient α. If the correction coefficient α in this case is, for example, 1.3, then the DRL value (4th diagnostic reference level L4) for dynamic imaging of the "lateral aspect of the lumbar spine" shown in Figure 6 is "13.5", so this is multiplied by the correction coefficient α = 1.3 to set "17.55" as the corrected DRL value.

[0109] As described above, the control unit 61 corrects the fourth diagnostic reference level L4, which is a diagnostic reference level, according to the part of the body.

[0110] (Example setting 4) In the above example setting 1, the target area (an example of the second area) was a different area from the predetermined area (an example of the first area), but the target area may be the same area as the predetermined area.

[0111] In this example setting, the ratio acquisition unit 611 acquires the ratio R=L2 / L1 based on the first diagnostic reference level L1 and the second diagnostic reference level L2, similar to the setting example 1 above.

[0112] In this example, the setting unit 612 also reads, for example, the third diagnostic reference level L3 stored in the memory unit 62. However, this third diagnostic reference level L3 is a value set by the imaging facility for when the target area, which is the same as the predetermined area, is photographed as a still image (general radiography), and is a different value from the first diagnostic reference level L1. Then, the setting unit 612 sets the fourth diagnostic reference level L4 (=L3×R) of the dose used for dose management when photographing the target area as a dynamic image, based on the third diagnostic reference level L3 and the ratio R.

[0113] For example, in general radiography, the incident surface dose for the front of the chest (100kV or higher) is specified as "0.3mGy" as the DRL value (first diagnostic reference level L1). Also, in dynamic radiography using the radiography imaging system 10 and radiography control device 20, the incident surface dose for the front of the chest (100kV or higher) is specified as "0.45mGy" as the DRL value (second diagnostic reference level L2). In this case, the ratio acquisition unit 611 of the control unit 61 calculates the ratio R = L2 / L1. In this example, the ratio R = 1.5.

[0114] The setting unit 612 of the control unit 61 sets the DRL value (4th diagnostic reference level L4) for dynamic imaging by multiplying the DRL value (3rd diagnostic reference level L3) set for general imaging by the above ratio R for "frontal chest (100kV or higher)". For example, suppose the DRL value (3rd diagnostic reference level L3) set for general imaging for "frontal chest (100kV or higher)" is "0.2mGy". The setting unit 612 multiplies "0.2mGy" by the above ratio R=1.5 to obtain and set "0.3mGy" as the DRL value (4th diagnostic reference level L4) for dynamic imaging for "frontal chest (100kV or higher)".

[0115] As described above, the control unit 61 sets a fourth diagnostic reference level L4, which is a diagnostic reference level unique to the imaging facility, even for dynamic imaging where a diagnostic reference level is defined.

[0116] In the above, the fourth diagnostic reference level L4 is set as a dose value for dose management, but it may also be set as a dose value that is the shooting condition for dynamic imaging.

[0117] The embodiments described above are merely examples of how the present invention can be implemented, and the technical scope of the present invention should not be interpreted as being limited by these embodiments. In other words, the present invention can be implemented in various forms without departing from its gist or its main features. [Explanation of symbols]

[0118] 10. Radiation imaging system 11. Image capture control unit 12 Radiation irradiation area 13 Shooting platform 14. Radiation detection unit 15 Display section 16 Audio output section 20. Radiography control device 30. Radiation Image Analysis Device 40 Image management device 50 client terminals 60. Dose control device 61 Control Unit 62 Storage section 63 Operation section 64 Display section 65 Communications Department 66 Bus 70 Modalities 100 Radiation Image Processing Systems 611 Ratio acquisition part 612 Settings Section 613 Correction Unit

Claims

1. A ratio acquisition unit that acquires the ratio of a first reference dose specified for when a first part of a subject is irradiated with radiation and a still image is taken of the subject, and a second reference dose specified for when the first part is irradiated with radiation and a dynamic image is taken of the subject, A setting unit sets a fourth reference dose for when the second part is photographed in motion, based on a third reference dose for when the second part is photographed in still image and the ratio, A dose control device equipped with the following features.

2. The second part is a different part from the first part. The third reference value is a value specified for the case where the second part is captured in a still image. The dose control device according to claim 1.

3. The second part is the same part as the first part, The third reference value is a value set for the case where the second part is captured as a still image, and is a different value from the first reference value. The dose control device according to claim 1.

4. The ratio acquisition unit determines the ratio using a fifth reference value for the dose, which is determined by the imaging facility itself, instead of the first reference value, when the first part is photographed with the still image. The dose control device according to claim 1.

5. The system includes a correction unit that corrects the fourth reference value according to the second part, The dose control device according to claim 1.

6. The correction unit corrects the fourth reference value according to the thickness of the second part. The dose control device according to claim 5.

7. If the second site is the chest, the system includes a correction unit that corrects the fourth reference value according to the respiratory state of the subject. The dose control device according to claim 1.

8. In a dose control device, The ratio of a first reference dose specified for the case where a first part of the subject is irradiated with radiation and a still image is taken, to a second reference dose specified for the case where the first part is irradiated with radiation and a dynamic image is taken, is determined. Based on the third reference dose for when the second part is photographed as a still image and the ratio, a fourth reference dose for when the second part is photographed as a moving image is set. Method for setting the dose.

9. The computer in the dose management device, A process to determine the ratio between a first reference dose specified for the case in which a first part of a subject is irradiated with radiation and a still image is taken, and a second reference dose specified for the case in which the first part is irradiated with radiation and a dynamic image is taken. A process to set a fourth reference dose for when the second part is photographed in motion, based on a third reference dose for when the second part is photographed in still image and the ratio, A dose setting program that executes the procedure.

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