Image processing device, image processing method, and program

Abstract

The X-ray CT image data should be displayed with an appropriate window width and window level when the energy value being displayed is changed. [Solution] The image processing apparatus according to the embodiment comprises a display control unit and a determination unit. The display control unit causes the display unit to display the first CT image data, which is displayed at a first keV value, at a first window width and a first window level. The determination unit determines the second window width and the second window level based on statistical information relating to the first window width, the first window level, the CT values ​​of a specific region corresponding to the first keV value and the second keV value, and the CT values ​​of a specific region corresponding to the first keV value and the second keV value. The display control unit causes the display unit to display the second CT image data at a second keV value at the determined second window width and second window level.

Description

Technical Field

[0001] The embodiments disclosed in this specification and the drawings relate to an image processing apparatus, an image processing method, and a program.

Background Art

[0002] Conventionally, X-ray computed tomography (CT) apparatuses, particularly dual energy (DE) CT apparatuses and photon counting (PC) CT apparatuses, can acquire X-ray energy information. Such DECT apparatuses and PCCT apparatuses can generate monochromatic image data (monochromatic X-ray image data) that depicts a subject at a single energy of an arbitrary value from data obtained by scanning the subject. Therefore, such DECT apparatuses and PCCT apparatuses can obtain a plurality of monochromatic image data having different X-ray energy values for the same cross-section from the data obtained by a single scan.

[0003] Since the contrast and signal-to-noise ratio of an image change when the energy value is different, when reading monochromatic image data, the user may display monochromatic image data corresponding to other energy values by changing the energy value (kilo electron Volt: keV) of the display target. In such a case, the visibility of the monochromatic image data corresponding to the changed energy value may decrease if the window width (Window Width: WW) and window level (Window Level: WL) before the change remain the same.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] One of the problems that the embodiments disclosed herein and in the drawings aim to solve is to display X-ray CT image data with an appropriate window width and window level in response to changes in the energy value of the display target. However, the problems that the embodiments disclosed herein and in the drawings aim to solve are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0006] The image processing apparatus according to the embodiment comprises a display control unit and a determination unit. The display control unit causes the display unit to display first CT image data, displayed at a first keV value, at a first window width and a first window level. The determination unit determines a second window width and a second window level, which are different from the first window width and the first window level, based on the first window width, the first window level, the CT value of a specific region corresponding to the first keV value, the CT value of a specific region corresponding to a second keV value different from the first keV value, statistical information relating to the CT value of a specific region corresponding to the first keV value, and statistical information relating to the CT value of a specific region corresponding to a second keV value. The display control unit causes the display unit to display second CT image data at the determined second window width and second window level. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 shows an example of a medical image processing system according to the first embodiment. [Figure 2] Figure 2 shows an example of the configuration of an X-ray CT apparatus according to the first embodiment. [Figure 3]Figure 3 shows an example of the configuration of a workstation according to the first embodiment. [Figure 4] Figure 4 shows an example of the configuration of the CT value database according to the first embodiment. [Figure 5] Figure 5 shows an example of changing the energy value of CT image data displayed on the display according to the first embodiment. [Figure 6] Figure 6 shows an example of the display of monochromatic image data related to the comparative example. [Figure 7] Figure 7 is a flowchart showing an example of the image display processing flow according to the first embodiment. [Modes for carrying out the invention]

[0008] The following describes in detail embodiments of the image processing apparatus, image processing method, and program with reference to the drawings.

[0009] (First Embodiment) Figure 1 shows an example of a medical image processing system S according to the first embodiment. As shown in Figure 1, the medical image processing system S includes, for example, an X-ray CT (Computed Tomography) device 1, a workstation 2, and a medical image storage device 3. The X-ray CT device 1, the workstation 2, and the medical image storage device 3 are connected to each other via a network N such as a hospital LAN (Local Area Network). In addition to the devices shown in Figure 1, the medical image processing system S may also include an electronic medical record system, a hospital information system (HIS), a laboratory information system (LIS), a radiology information system (RIS), etc., or may be included as part of these systems, or may be connected to these systems in a communicative manner.

[0010] The X-ray CT apparatus 1 acquires CT image data of a subject by X-ray scanning the subject. More specifically, the X-ray CT apparatus 1 in this embodiment is a dual-energy (DE) CT apparatus or a photon counting (PC) CT apparatus capable of acquiring CT image data corresponding to multiple energy values. In this embodiment, the term "CT image data" refers to both multi-energy data corresponding to multiple energy values ​​and monochromatic image data corresponding to a specific energy value.

[0011] Workstation 2 is a computer composed of a PC (Personal Computer) or a server, etc. Workstation 2 displays CT image data based on scans performed by X-ray CT apparatus 1 in various ways, for example. Workstation 2 is an example of an image processing apparatus in this embodiment.

[0012] The medical image storage device 3 is a device for storing medical image data of a subject. The medical image storage device 3 includes, for example, a processing circuit such as a processor, a storage circuit, a network interface, an input interface, and a display. More specifically, the medical image storage device 3 is, for example, a PACS (Picture Archiving and Communication System) server device and stores medical image data in a format compliant with DICOM (Digital Imaging and Communications in Medicine). The medical image data is, for example, CT image data.

[0013] Here, we will explain the configuration of the X-ray CT scanner 1.

[0014] FIG. 2 is a diagram showing an example of the configuration of the X-ray CT apparatus 1 according to the first embodiment. The X-ray CT apparatus 1 of the present embodiment is a DECT apparatus capable of collecting detection data of X-rays corresponding to two or more types of energy values (tube voltages). The X-ray CT apparatus 1 collects, for example, detection data of X-rays corresponding to two types of energy values (tube voltages) of at least 135 kVp (kilo Volt Peak) and 80 kVp.

[0015] As shown in FIG. 2, the X-ray CT apparatus 1 includes a gantry apparatus 10, a couch apparatus 30, and a console apparatus 40. In the present embodiment, the rotation axis of the rotating frame 13 or the longitudinal direction of the top plate 33 of the couch apparatus 30 in the non-tilt state is defined as the Z-axis direction, the axial direction orthogonal to the Z-axis direction and horizontal with respect to the floor surface is defined as the X-axis direction, and the axial direction orthogonal to the Z-axis direction and perpendicular to the floor surface is defined as the Y-axis direction. In FIG. 2, for convenience of explanation, a plurality of gantry apparatuses 10 are drawn, but in the actual configuration of the X-ray CT apparatus 1, there is only one gantry apparatus 10.

[0016] The gantry apparatus 10 and the couch apparatus 30 operate based on an operation from a user via the console apparatus 40 or an operation from a user via an operation unit provided in the gantry apparatus 10 or the couch apparatus 30. The gantry apparatus 10, the couch apparatus 30, and the console apparatus 40 are connected to each other in a communicable manner by wire or wirelessly.

[0017] The gantry apparatus 10 is an apparatus having an imaging system that irradiates a subject P with X-rays and collects detection data of the X-rays transmitted through the subject P. More specifically, the gantry apparatus 10 includes an X-ray tube 11 (X-ray generation unit), a wedge 16, a collimator 17, an X-ray detector 12, an X-ray high voltage apparatus 14, a DAS (Data Acquisition System) 18, a rotating frame 13, and a control apparatus 15.

[0018] The X-ray tube 11 is a vacuum tube that generates X-rays by irradiating thermoelectrons from the cathode (filament) toward the anode (target) by applying a high voltage from the X-ray high-voltage device 14 and supplying a filament current. X-rays are generated when the thermoelectrons collide with the target. The X-rays generated at the tube focus in the X-ray tube 11 are shaped into a cone beam shape through, for example, the collimator 17 and irradiated onto the subject P. For example, the X-ray tube 11 includes a rotating anode type X-ray tube that generates X-rays by irradiating thermoelectrons onto the rotating anode.

[0019] The X-ray tube 11 of the present embodiment generates X-rays with two voltage values of 135 kVp and 80 kVp. As a method for generating X-rays with two voltage values, for example, there is rapid kV switching that rapidly switches between two high and low tube voltages in one scan, but other methods may be adopted. For example, the X-ray CT apparatus 1 may include two X-ray tubes 11 that generate different tube voltages. Alternatively, a dual layer detector method that separates the X-rays generated by the X-ray tube 11 into two energy values on the X-ray detector 12 side may be adopted.

[0020] The X-ray detector 12 detects the X-rays irradiated from the X-ray tube 11 and outputs an electrical signal corresponding to the detected X-ray dose to the DAS 18.

[0021] The rotating frame 13 supports the X-ray tube 11 and the X-ray detector 12 so as to be rotatable about the rotation axis. In addition to the X-ray tube 11 and the X-ray detector 12, the rotating frame 13 further supports the X-ray high-voltage device 14 and the DAS 18. Such a rotating frame 13 is housed in a substantially cylindrical housing in which an opening (bore) forming a imaging space is formed.

[0022] The X-ray high-voltage device 14 includes an electrical circuit such as a transformer and a rectifier, a high-voltage generator that has the function of generating a high voltage to be applied to the X-ray tube 11 and a filament current to be supplied to the X-ray tube 11, and an X-ray control device that controls the output voltage according to the X-rays irradiated by the X-ray tube 11. The high-voltage generator may be of the transformer type or the inverter type. The X-ray high-voltage device 14 may be installed on the rotating frame 13 or on the fixed frame (not shown) side of the mounting device 10.

[0023] The control device 15 is equipped with a processing circuit such as a CPU (Central Processing Unit) and has the function of controlling the operation of the frame device 10 and the bed device 30 by receiving input signals from the console device 40 or the input interface 43 attached to the frame device 10. For example, the control device 15 receives input signals and controls the rotation of the rotating frame 13, the tilt of the frame device 10, and the operation of the bed device 30 and the top plate 33. The control of tilting the frame device 10 may be achieved by the control device 15 rotating the rotating frame 13 around an axis parallel to the X-axis direction based on the tilt angle information input by the input interface 43 attached to the frame device 10. The control device 15 may be installed on the frame device 10 or on the console device 40.

[0024] The wedge 16 is a filter for adjusting the amount of X-rays emitted from the X-ray tube 11. Specifically, the wedge 16 is a filter that transmits and attenuates the X-rays emitted from the X-ray tube 11 so that the X-rays emitted from the X-ray tube 11 to the subject P have a predetermined distribution. The wedge 16 is, for example, a wedge filter or bow-tie filter, and is a filter made of aluminum processed to have a predetermined target angle and a predetermined thickness.

[0025] The collimator 17 is a lead plate or the like used to focus the X-rays that have passed through the wedge 16 into the X-ray irradiation area, and a slit is formed by combining multiple lead plates or the like.

[0026] DAS18 collects detection data related to the subject P. More specifically, DAS18 collects the signal detected by the X-ray detector 12. DAS18 includes, for example, an amplifier, an A / D (analog-to-digital) converter, and a control circuit. DAS18 may also include other components. Furthermore, under the control of the control device 15, DAS18 transmits (transfers) detection data (raw data) based on the X-ray detection results acquired from the X-ray detector 12 to the console device 40. DAS18 may be directly connected to the console device 40 for communication or connected via the control device 15.

[0027] The patient bed device 30 is a device for placing and moving the subject P to be scanned, and comprises a base 31, a patient bed drive device 32, a tabletop 33, and a tabletop support frame 34. The base 31 is a housing that supports the tabletop support frame 34 so that it can move vertically. The patient bed drive device 32 is a motor or actuator that moves the tabletop 33 on which the subject P is placed along the long axis of the tabletop 33. The patient bed drive device 32 moves the tabletop 33 according to the control of the console device 40 or the control device 15. The tabletop 33, which is provided on the upper surface of the tabletop support frame 34, is a plate on which the subject P is placed. In addition to the tabletop 33, the patient bed drive device 32 may also move the tabletop support frame 34 along the long axis of the tabletop 33.

[0028] The console device 40 is a device that controls the rigging device 10 and generates CT image data based on the scan results from the rigging device 10. The console device 40 has a memory 41 (storage unit), a display 42 (display unit), an input interface 43 (input unit), a processing circuit 44 (processing unit), and a network interface 45 (communication unit). Data communication between the memory 41, the display 42, the input interface 43, the processing circuit 44, and the network interface 45 is performed via a bus (BUS).

[0029] Memory 41 is a storage device such as an HDD (Hard Disk Drive), SSD (Solid State Drive), or integrated circuit storage device that stores various types of information. For example, memory 41 stores projection data and reconstructed image data. In addition to HDDs and SSDs, memory 41 may also be a drive device that reads and writes various types of information to portable storage media such as CDs (Compact Discs), DVDs (Digital Versatile Discs), and flash memory, or semiconductor memory elements such as RAM (Random Access Memory). Furthermore, the storage area of ​​memory 41 may be located within the X-ray CT apparatus 1 or in an external storage device connected via a network. Memory 41 also stores the control program for the console device 40 according to this embodiment.

[0030] The display 42 displays various types of information. For example, the display 42 outputs medical images (CT images) generated by the processing circuit 44, a GUI (Graphical User Interface) for receiving various operations from the operator, etc. For example, the display 42 can be a liquid crystal display (LCD), an organic electroluminescent display (OELD), a plasma display, or any other display as appropriate. The display 42 may also be mounted on the stand device 10. The display 42 may be a desktop type, or it may consist of a tablet terminal or the like that can communicate wirelessly with the console device 40.

[0031] The input interface 43 receives various input operations from the operator and converts the received input operations into electrical signals, which are then output to the processing circuit 44. For example, the input interface 43 receives data collection conditions when collecting detection data, reconstruction conditions when reconstructing CT image data, and image processing conditions for CT image data from the operator. The input interface 43 can be appropriately configured to include, for example, a mouse, keyboard, trackball, switch, button, joystick, touchpad, and touch panel display.

[0032] In this embodiment, the input interface 43 is not limited to those comprising physical operating components such as a mouse, keyboard, trackball, switch, button, joystick, touchpad, and touch panel display. For example, an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and outputs this electrical signal to the processing circuit 44 is also included as an example of the input interface 43. Furthermore, the input interface 43 is an example of an input unit. The input interface 43 may also be provided on the mounting device 10. In addition, the input interface 43 may consist of a tablet terminal or the like that can communicate wirelessly with the console device 40 main unit.

[0033] The network interface 45 is connected to the processing circuit 44 and controls the transmission and communication of various data between the device connected via the network N. For example, the network interface 45 may be implemented by a network card, network adapter, NIC (Network Interface Controller), etc.

[0034] The processing circuit 44 is a processor that reads and executes programs from the memory 41 to realize functions corresponding to each program. For example, the processing circuit 44 includes a control function 441, a preprocessing function 442, a reconstruction function 443, an image processing function 444, and a transmission function 445. The control function 441 is an example of a control unit. The preprocessing function 442 is an example of a preprocessing unit. The reconstruction function 443 is an example of a reconstruction unit. The image processing function 444 is an example of an image processing unit. The transmission function 445 is an example of a transmission unit.

[0035] Here, for example, the control function 441, preprocessing function 442, reconstruction function 443, image processing function 444, and transmission function 445, which are components of the processing circuit 44, are stored in memory 41 in the form of programs that can be executed by a computer. In other words, the processing circuit 44, when each program has been read, will have the functions shown in the processing circuit 44 of Figure 2. In Figure 2, the processing functions performed by the control function 441, preprocessing function 442, reconstruction function 443, image processing function 444, and transmission function 445 are explained as being realized by a single processor, but the processing circuit 44 may also be configured by combining multiple independent processors, and each processor may realize the functions by executing a program. Also, in Figure 2, the memory 41 is explained as storing the programs corresponding to each processing function, but multiple memory circuits may be distributed and arranged so that the processing circuit 44 reads the corresponding programs from individual memory circuits.

[0036] The above description illustrates an example in which a "processor" reads and executes programs corresponding to each function from a memory circuit, but the embodiments are not limited to this. The term "processor" refers to circuits such as a CPU (Central Processing Unit), GPU (Graphics Processing Unit), Application Specific Integrated Circuit (ASIC), and Programmable Logic Device (e.g., Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA)). If the processor is a CPU, for example, it realizes its functions by reading and executing programs stored in memory 41. On the other hand, if the processor is an ASIC, instead of storing programs in memory 41, the functions are directly incorporated as logic circuits within the processor's circuitry. In this embodiment, each processor is not limited to being configured as a single circuit; multiple independent circuits may be combined to form a single processor and realize its functions. Furthermore, multiple components shown in Figure 2 may be integrated into a single processor to realize its functions.

[0037] The control function 441 controls various processes based on input operations received from the operator via the input interface 43. Specifically, the control function 441 controls the CT scan performed by the pallet machine 10. For example, the control function 441 controls the collection of detection data of X-rays that have passed through the subject P in the pallet machine 10 by controlling the operation of the X-ray high-voltage device 14, the X-ray detector 12, the control device 15, the DAS 18, and the patient table drive device 32.

[0038] The preprocessing function 442 generates projection data by applying preprocessing such as logarithmic transformation, offset correction, inter-channel sensitivity correction, and beam hardening correction to the detection data output from DAS18.

[0039] The reconstruction function 443 generates CT image data by performing a reconstruction process on the projection data generated by the preprocessing function 442, using methods such as filtered back projection (FBP). Since the X-ray CT apparatus 1 of this embodiment is a DECT apparatus capable of collecting X-ray detection data corresponding to two types of energy values ​​(tube voltage), the reconstruction function 443 generates multi-energy data corresponding to multiple energy values ​​through the reconstruction process.

[0040] The reconstruction process includes various correction processes such as scattering correction and beam hardening correction, as well as the application of a reconstruction function under reconstruction conditions. The reconstruction process performed by the reconstruction function 443 is not limited to the FBP method; known processes such as iterative reconstruction and deep neural networks that output a reconstructed image from projection data input may be used as appropriate. The reconstruction function 443 stores the reconstructed CT image data in the memory 41.

[0041] In this embodiment, the data before preprocessing is referred to as raw data (detection data), the detection data preprocessed by the preprocessing function 442 is referred to as projection data, and the projection data reconstructed by the reconstruction function 443 is referred to as CT image data.

[0042] The image processing function 444 converts the CT image data generated by the reconstruction function 443 into tomographic image data of an arbitrary cross-section or 3D image data using a known method, based on input operations received from the operator via the input interface 43. For example, the image processing function 444 may generate monochromatic image data from multi-energy data. The generation of 3D image data and monochromatic image data may also be performed by the reconstruction function 443. Furthermore, the image processing function 444 may add supplementary information such as patient information of subject P and examination date and time to the multi-energy data and monochromatic image data.

[0043] The transmission function 445 transmits CT image data to the workstation 2 and the medical image storage device 3 via the network interface 45 and the network N. For example, the transmission function 445 transmits multi-energy data and monochromatic image data to the medical image storage device 3. The CT image data may be transmitted to the medical image storage device 3 from the X-ray CT device 1 or from the workstation 2.

[0044] Next, we will describe the configuration of workstation 2.

[0045] Figure 3 shows an example of the configuration of a workstation 2 according to the first embodiment. As shown in Figure 3, the workstation 2 includes, for example, a network interface 21, a memory circuit 22, a processing circuit 23, an input interface 24, and a display 25.

[0046] The network interface 21 receives CT image data transmitted from the X-ray CT device 1 via the network N. The network interface 21 may also receive CT image data from the medical image storage device 3. Furthermore, the network interface 21 may acquire various information such as CT scan examination orders and imaging conditions from the X-ray CT device 1 or other systems.

[0047] The memory circuit 22 stores various programs and various data used in the processing of the workstation 2. The memory circuit 22 is implemented using semiconductor memory elements such as ROM (Read Only Memory), RAM, and flash memory, as well as hard disks, optical discs, etc. The memory circuit 22 can also be used as a hardware-based non-transient storage medium. The memory circuit 22 is an example of a memory unit.

[0048] Furthermore, the memory circuit 22 stores, for example, the CT value of a specific region and statistical information related to the CT value, associating them with the energy value to be displayed. The CT value of a specific region stored in the memory circuit 22 is, for example, a representative value. The statistical information related to the CT value is, for example, the standard deviation (SD), median, and variance of the CT value. In this embodiment, the case where the statistical information related to the CT value is the standard deviation of the CT value will be explained as an example. For example, the memory circuit 22 stores a CT value database 22a in which the representative value and the standard deviation of the CT value of a specific region are registered as associations. The memory circuit 22 also stores coefficient information 22b.

[0049] Figure 4 shows an example of the configuration of the CT value database 22a according to the first embodiment. As shown in Figure 4, the CT value database 22a is a database that associates the energy value (keV) to be displayed with the representative value of the CT value of the fat region and the standard deviation of the CT value of the fat region. The representative value of the CT value of a specific region and the standard deviation of the CT value of a specific region registered in the CT value database 22a are information used in the automatic window width and window level change processing described later.

[0050] The specific region is the area that serves as the basis for the window width and window level when displaying CT image data. In other words, in the automatic window width and window level adjustment process described later, the window width and window level that allow the specific region in the CT image data to be displayed clearly are identified.

[0051] The specific region is, for example, the soft tissue in subject P. More specifically, in this embodiment, the specific region is the fat region, or the region in which any organ specified by the user or the CT scan examination order is depicted. For example, if the CT scan is an examination focusing on the liver, the specific region may be the liver. In the following, this embodiment will describe the case where the specific region is the fat region as an example.

[0052] The energy values ​​shown in Figure 4 are examples only and are not limited to the values ​​shown in Figure 4.

[0053] The representative CT values ​​of the adipose region registered in the CT value database 22a are the general CT values ​​of the adipose region at each energy value. The CT values ​​of the adipose region may be the average of the CT values ​​of the adipose region from multiple CT image data generated in the past, or they may be theoretical values.

[0054] The standard deviation of the CT values ​​of the fat region registered in the CT value database 22a is the standard deviation of the CT values ​​of the fat region for each energy value. The standard deviation of the CT values ​​of the fat region may be a value calculated from the CT values ​​of the fat region of multiple CT image data generated in the past, or it may be a theoretical value.

[0055] The coefficient information 22b consists of the values ​​of coefficients α and β, which are used in the automatic window width and window level change processing described later. The values ​​of coefficients α and β are predetermined and stored in the memory circuit 22. Coefficients α and β will be described later.

[0056] The input interface 24 can be implemented by, for example, a trackball, switch buttons, a mouse, a keyboard, etc. However, in this embodiment, the input interface 24 is not limited to those equipped with physical operating components such as a mouse or keyboard. For example, an electrical signal processing circuit that receives electrical signals corresponding to input operations from an external input device provided separately from the workstation 2 and outputs these electrical signals to the processing circuit 23 is also included as an example of the input interface 24.

[0057] The input interface 24 is connected to the processing circuit 23 and converts various input operations received from the operator into electrical signals, which are then output to the processing circuit 23.

[0058] The display 25 displays CT image data and various GUIs under the control of the processing circuit 23. The display 25 is an example of a display unit.

[0059] The processing circuit 23 is a processor that controls the entire workstation 2. The processing circuit 23 includes an acquisition function 231, a reception function 232, a decision function 233, and a display control function 234. The acquisition function 231 is an example of an acquisition unit. The reception function 232 is an example of a reception unit. The decision function 233 is an example of a decision unit. The display control function 234 is an example of a display control unit.

[0060] Here, for example, the processing functions of the processing circuit 23, namely the acquisition function 231, the reception function 232, the decision function 233, and the display control function 234, are stored in the memory circuit 22 in the form of a program that can be executed by a computer. In other words, the processing circuit 23, when each program has been read, will have the functions shown in the processing circuit 23 of Figure 3. In Figure 3, it has been explained that the processing functions performed by the acquisition function 231, the reception function 232, the decision function 233, and the display control function 234 are realized by a single processor, but the processing circuit 23 may also be configured by combining multiple independent processors, with each processor realizing the functions by executing a program. Also, in Figure 3, it has been explained that a single memory circuit 22 stores the programs corresponding to each processing function, but it is also possible to have multiple memory circuits distributed and the processing circuit 23 read the corresponding programs from individual memory circuits.

[0061] The above description illustrates an example in which the "processor" reads and executes programs corresponding to each function from a memory circuit, but the embodiments are not limited to this. The term "processor" refers to circuits such as CPUs, GPUs, ASICs, and programmable logic devices. If the processor is a CPU, for example, the processor realizes its functions by reading and executing programs stored in the memory circuit 22. On the other hand, if the processor is an ASIC, instead of storing programs in the memory circuit 22, the functions are directly incorporated as logic circuits within the processor's circuitry. In this embodiment, each processor is not limited to being configured as a single circuit; multiple independent circuits may be combined to form a single processor and realize its functions. Furthermore, the multiple components shown in Figure 3 may be integrated into a single processor to realize its functions.

[0062] The acquisition function 231 acquires various data via the network interface 21. More specifically, the acquisition function 231 acquires CT image data from the X-ray CT device 1 or the medical image storage device 3. For example, the acquisition function 231 acquires multi-energy data corresponding to multiple energy values, or multiple monochromatic image data, each corresponding to a single energy value. The acquisition function 231 may also acquire various information such as the CT scan examination order and imaging conditions from the X-ray CT device 1 or other systems.

[0063] The reception function 232 accepts various user operations via the input interface 24. For example, the reception function 232 accepts user operations to change the energy value of the CT image data to be displayed on the display 25.

[0064] The operation to change the energy value of the CT image data to be displayed is, in the case where the CT image data is monochromatic image data, the operation to display monochromatic image data with a different energy value from a state where monochromatic image data with a certain energy value is displayed on the display 25. In this case, the monochromatic image data with the energy value before the change and the monochromatic image data with the other energy value after the change are the same cross-sectional image data acquired from the same subject P in a single scan. In this embodiment, such an operation to change the energy value of the CT image data to be displayed is called a change operation. In other words, a change operation is an operation to display the same cross-section of the same subject P with monochromatic image data corresponding to different energy values.

[0065] For example, multiple monochromatic image data corresponding to different energy values ​​captured by subject P in a single scan may be stored in the memory circuit 22 as a single set of monochromatic image data. Alternatively, multi-energy data capable of generating multiple monochromatic image data corresponding to different energy values ​​may be stored in the memory circuit 22.

[0066] The determination function 233 determines the window width and window level for displaying monochromatic image data corresponding to the changed energy value when the user has requested a change in the energy value of the CT image data to be displayed.

[0067] The display control function 234 causes the display 25 to display various CT image data. More specifically, the display control function 234 causes the display 25 to display monochromatic image data at the window width and window level determined by the determination function 233.

[0068] Figure 5 shows an example of changing the energy value of CT image data displayed on the display 25 according to the first embodiment. In the example shown in Figure 5, the display control function 234 displays a slider bar 81 superimposed on the monochromatic image data, which allows the user to change the energy value of the monochromatic image data to be displayed. Operating the slider bar 81 to change the energy value of the displayed data is one example of a change operation. Note that the change operation is not limited to operating the slider bar 81, and may also be an operation to input an energy value, an operation to select from a list box, etc.

[0069] In the example shown in Figure 5, monochromatic image data 90a corresponding to an energy value of 70 keV is displayed first. The display control function 234 displays the monochromatic image data 90a corresponding to the energy value of 70 keV with, for example, a window width of "380" and a window level of "40". The window width and window level of the monochromatic image data 90a may be values ​​manually set by the user, or predetermined values. For example, the memory circuit 22 may store initial values ​​for the window width and window level corresponding to each energy value, and the display control function 234 may first display the monochromatic image data 90a with these initial values. Alternatively, the user may manually change the window width and window level of the monochromatic image data 90a from the initial values.

[0070] Here, the user can operate the slider bar 81 to display monochromatic image data 90b corresponding to an energy value of 35 keV, which is lower than 70 keV. The reception function 232 accepts the 35 keV energy value indicated by the slider bar 81 operated by the user as the changed energy value. In other words, the reception function 232 accepts the user's change operation to change the display target on the display 25 from monochromatic image data 90a corresponding to an energy value of 70 keV to monochromatic image data 90b corresponding to an energy value of 35 keV.

[0071] When the reception function 232 receives a change operation from the user, the determination function 233 determines an appropriate window width and window level for displaying the Monochromatic image data 90b corresponding to the changed energy value, based on the window width and window level of the Monochromatic image data 90a before the change, the representative value of the CT value of a specific region corresponding to the energy value before and after the change, and the standard deviation of the CT value of a specific region corresponding to the energy value before and after the change. Generally, the appropriate window width and window level will differ if the energy value of the display target is different.

[0072] More specifically, the decision function 233 determines the window width and window level for displaying the Monochromatic image data 90b corresponding to the energy value specified by the user's modification operation, according to the following equations (1) and (2). In equations (1) and (2), the window width (WW) and window level (WL) of the Monochromatic image data 90a that were displayed before the modification operation are referred to as "WW before modification" and "WL before modification," respectively. The window width and window level suitable for displaying the Monochromatic image data 90b corresponding to the energy value specified by the user's modification operation are referred to as "WW after modification" and "WL after modification."

[0073] WW after modification = WW before modification + (Difference between the standard deviation of the CT value in a specific region corresponding to the modified energy value and the standard deviation of the CT value in a specific region corresponding to the original energy value) × α...(1) Modified WL = Original WL + (Difference between the CT value of a specific region corresponding to the modified energy value and the CT value of a specific region corresponding to the original energy value) × β...(2)

[0074] The determination function 233 reads and uses the "standard deviation of the CT value of the specific region corresponding to the changed energy value," the "standard deviation of the CT value of the specific region corresponding to the energy value before the change," the "CT value of the specific region corresponding to the changed energy value," and the "CT value of the specific region corresponding to the energy value before the change" from the CT value database 22a stored in the memory circuit 22. The determination function 233 also reads and uses the coefficients α and β in equations (1) and (2) from the coefficient information 22b stored in the memory circuit 22.

[0075] Applying equations (1) and (2) to the example shown in Figure 5, the decision function 233 calculates the window width and window level for displaying Monochromatic image data 90b corresponding to the energy value "35keV" specified by the user's change operation, as shown in equations (1)' and (2)' below, if the energy value of Monochromatic image data 90a displayed before the user's change operation was 70keV and the energy value specified as the display target in the change operation is 35keV.

[0076] WW at 35keV = WW at 70keV + (Difference between the standard deviation of CT values ​​in the fatty region at 35keV and the standard deviation of CT values ​​in the fatty region at 70keV) × α···(1)´ WL at 35 keV = WL at 70 keV + (difference between CT value of the adipose region at 35 keV and CT value of the adipose region at 70 keV) × β···(2)´

[0077] The monochromatic image data 90a shown in Figure 5 is an example of the first CT image data in this embodiment. The monochromatic image data 90b is an example of the second CT image data in this embodiment. The energy value "70 keV" of the original monochromatic image data 90a is an example of the first keV value. The energy value "35 keV" of the modified monochromatic image data 90b is an example of the second keV value. The window width "380" and window level "40" of the original monochromatic image data 90a are examples of the first window width and first window level. The window width "667" and window level "82" of the modified monochromatic image data 90b are examples of the second window width and second window level.

[0078] When the reception function 232 receives a change operation from the user, the display control function 234 causes the display 25 to display monochromatic image data 90b with the changed window width and changed window level determined by the decision function 233.

[0079] The display control function 234 may generate monochromatic image data 90a and 90b from multi-energy data corresponding to multiple energy values ​​in response to user operation and display them on the display 25. Alternatively, the display control function 234 may read monochromatic image data 90a and 90b that have been pre-generated corresponding to a single energy value from the memory circuit 22 in response to user operation and display them on the display 25. Known methods can be used for the format in which the memory circuit 22 stores information on multi-energy data or monochromatic image data 90a and 90b, and for the method by which the display control function 234 reads this information.

[0080] Monochromatic image data 90a and monochromatic image data 90b are CT image data corresponding to different energy values, but they are the same cross-sectional image data acquired from the same subject P in a single scan. For example, monochromatic image data 90a and monochromatic image data 90b are CT image data generated from a single multi-energy data set.

[0081] By manipulating the slider bar 81, the user can display monochromatic image data 90a and 90b, which are images at any single energy value, by changing the target energy value. Hereafter, when monochromatic image data 90a and 90b are not distinguished, they will simply be referred to as monochromatic image data 90. Also, since monochromatic image data 90b corresponds to a lower energy value than monochromatic image data 90a, it will also be called low keV image data.

[0082] Generally, monochromatic image data 90b, which corresponds to a lower energy value (e.g., 35 keV), can enhance the contrast of the depicted organs more effectively than monochromatic image data 90a, which corresponds to a standard energy value (e.g., 70 keV). On the other hand, low-keV image data such as monochromatic image data 90b has a high CT value. Therefore, if monochromatic image data 90b is displayed with the same window width and window level as monochromatic image data 90a, the display on the display 25 may become too bright, reducing visibility for the user.

[0083] Figure 6 shows an example of the display of monochromatic image data 91a and 91b related to the comparative example. In the example shown in Figure 6, monochromatic image data 91a corresponds to an energy value of 70 keV, and monochromatic image data 91b corresponds to an energy value of 35 keV.

[0084] In Figure 6, the monochromatic image data 91a is displayed on the display 25 with a window width of "380" and a window level of "40". The user then changes the energy value of the displayed image to 35 keV through a modification operation.

[0085] In Figure 6, the 35keV monochromatic image data 91b is displayed on the display 25 with the same window width "380" and window level "40" as before the change. As a result, the display on the display 25 is brighter for monochromatic image data 91b than for the 70keV monochromatic image data 91a and the 35keV monochromatic image data 90b shown in Figure 5, and some areas are overexposed, reducing the visibility of organs. In particular, soft tissues such as fatty regions are prone to such overexposure if low-keV image data is not displayed with an appropriate window width and window level.

[0086] In contrast, in Figure 5 above, when the energy value of the displayed object was changed from 70 keV to 35 keV, the window width and window level were changed to values ​​suitable for displaying the 35 keV monochromatic image data 90b. As a result, the 35 keV monochromatic image data 90b shown in Figure 5 does not exhibit overexposure compared to the comparative example 35 keV monochromatic image data 91b shown in Figure 6, and visibility is maintained.

[0087] Here, we will describe the flow of image display processing, including the automatic window width and window level change process, which is performed on workstation 2 configured as described above.

[0088] Figure 7 is a flowchart showing an example of the image display processing flow according to the first embodiment. Before this flowchart is executed, CT image data is acquired from the X-ray CT apparatus 1 or the medical image storage device 3. The CT image data may be multi-energy data corresponding to multiple energy values ​​(e.g., 35 keV, 70 keV) or single-energy data corresponding to multiple tube voltage values.

[0089] The reception function 232 accepts the user's specification of the CT image data to be displayed (S1). For example, the reception function 232 may accept the user's input of patient information or examination date and time, etc., to specify the multi-energy data to be displayed, or a set of monochromatic image data 90 including monochromatic image data 90a, 90b. Alternatively, the display control function 234 may display a selection screen on the display 25 showing thumbnail images of the CT image data to be displayed, allowing the user to make a selection.

[0090] When the display control function 234 receives a specification of CT image data to be displayed by the user, it displays the Monochromatic image data 90 corresponding to a representative energy value from the selected CT image data on the display 25 (S2). Here, 70 keV is used as an example of a representative energy value. The representative energy value may be stored in the memory circuit 22 in association with multi-energy data or Monochromatic image data 90a, 90b, for example, or it may be specified in advance by the user. The display control function 234 displays the Monochromatic image data 90a corresponding to 70 keV from the multi-energy data or set of Monochromatic image data 90 selected by the user, with the initial window width and window level corresponding to 70 keV.

[0091] Although not shown in Figure 7, the user may change the window width and window level for displaying the monochromatic image data 90a from their default values ​​by operating the input interface 24. When the reception function 232 receives a request from the user to change the window width and window level, the display control function 234 displays the monochromatic image data 90a at the changed window width and window level.

[0092] Then, when the reception function 232 receives a user request to change the energy value (keV) (S3 "Yes"), the determination function 233 calculates a window width and window level suitable for displaying the CT image data with the changed energy value (S4). Specifically, the determination function 233 uses equations (1) and (2) described above to calculate a window width and window level suitable for displaying the CT image data with the changed energy value (for example, if the changed energy value is 35 keV, then Monochromatic image data 90b). Note that if the window width and window level for displaying Monochromatic image data 90a have been changed by the user from their initial values ​​at the time of S3, then the "WW before change" and "WL before change" used in equations (1) and (2) will be the window width and window level changed by the user.

[0093] Then, the display control function 234 displays the modified energy value CT image data (for example, monochromatic image data 90b) on the display 25 with a window width and window level suitable for displaying the modified energy value CT image data calculated by the determination function 233 (S5).

[0094] Then, if the reception function 232 has not received a request from the user to end the display of CT image data (S6 "No"), the process returns to S3.

[0095] If the reception function 232 has not received a request from the user to change the energy value (keV) (S3 "No"), the reception function 232 will wait for the user's operation.

[0096] Furthermore, if the reception function 232 receives a request from the user to end the display of CT image data (S6 "Yes"), the processing of this flowchart ends.

[0097] Thus, the workstation 2 of this embodiment determines a suitable window width and window level for displaying the Monochromatic image data 90b corresponding to the changed energy value, based on the current window width, current window level, CT value of a specific region corresponding to the energy value before and after the change, and the standard deviation of the CT value of the specific region corresponding to the energy value before and after the change of the displayed Monochromatic image data 90a, and displays the Monochromatic image data 90b at the determined window width and window level. For this reason, according to the workstation 2 of this embodiment, the Monochromatic image data 90b can be displayed at an appropriate window width and window level in response to a change in the energy value to be displayed.

[0098] For example, as mentioned above, the contrast changes when the energy value of the displayed object differs. Therefore, displaying monochromatic image data 90a and 90b corresponding to different energy values ​​with the same window width and window level may result in overexposure. For this reason, manually adjusting the window width and window level each time the user changes the energy value of the displayed object during image interpretation is time-consuming and may interrupt the image interpretation process. Furthermore, if the user has adjusted the window width and window level appropriately for the 70keV monochromatic image data 90a before the change, resetting the adjusted window width and window level and displaying the changed 35keV monochromatic image data 90b will result in repeated adjustments and wasted effort. The workstation 2 of this embodiment can reduce the time and waste associated with such operations.

[0099] Furthermore, in this embodiment, when the workstation 2 receives a user operation to change the energy value of the display target while the monochromatic image data 90a is being displayed, it determines a suitable window width and window level for displaying the monochromatic image data 90b corresponding to the changed energy value, and displays the monochromatic image data 90b at the determined window width and window level. Therefore, according to the workstation 2 of this embodiment, the user can change the energy value of the display target at a desired timing while the monochromatic image data 90a is being displayed, and view the changed monochromatic image data 90b at an appropriate window width and window level.

[0100] Furthermore, the workstation 2 of this embodiment includes a storage circuit 22 in which a CT value database 22a is stored. Based on the representative value of the CT value of a specific region and the standard deviation of the CT value of the specific region in the energy values ​​before and after the change, which are registered in the CT value database 22a, the workstation 2 of this embodiment determines a suitable window width and window level for displaying monochromatic image data 90b corresponding to the changed energy value. Therefore, according to the workstation 2 of this embodiment, the computational load and time required for determining the window width and window level can be reduced by using the pre-stored CT value and standard deviation.

[0101] Furthermore, in this embodiment, the specific region is either a fatty region or a region in which any organ specified by the user or examination order is depicted. Fatty regions are prone to overexposure in low-keV data and are easily affected if the window width and window level are not appropriate. In addition, by prioritizing the visibility of any organ specified by the user or examination order, the accuracy of image interpretation for that organ can be improved.

[0102] Furthermore, in this embodiment, as an example of multiple CT image data corresponding to different energy values, Monochromatic image data 90a and 90b obtained from the same scan of subject P are given. Since the appearance of Monochromatic image data 90 differs depending on the energy value, there is a need for the user to change the corresponding energy value when interpreting the image and display multiple Monochromatic image data 90a and 90b with an appropriate window width and window level.

[0103] (Second embodiment) In the first embodiment described above, the workstation 2 pre-stored the CT value database 22a in the memory circuit 22. In contrast, the workstation 2 of this embodiment dynamically identifies the representative value of the CT value in a specific region and the standard deviation of the CT value in a specific region from the CT image data to be displayed.

[0104] The medical image processing system S of this embodiment comprises an X-ray CT scanner 1, a workstation 2, and a medical image storage device 3, similar to the first embodiment. The configurations of the X-ray CT scanner 1 and the medical image storage device 3 are the same as in the first embodiment.

[0105] Furthermore, the workstation 2 of this embodiment includes a network interface 21, a memory circuit 22, a processing circuit 23, an input interface 24, and a display 25, similar to the first embodiment.

[0106] The processing circuit 23 of the workstation 2 in this embodiment includes an acquisition function 231, a reception function 232, a determination function 233, and a display control function 234, similar to the first embodiment.

[0107] The acquisition function 231, the reception function 232, and the display control function 234 have the same functions as in the first embodiment.

[0108] In addition to the same functions as in the first embodiment, the determination function 233 of this embodiment identifies representative values ​​and standard deviations of CT values ​​for specific regions from monochromatic image data 90a and 90b. For example, the determination function 233 recognizes specific regions (e.g., fat regions) from monochromatic image data 90a and monochromatic image data 90b respectively through image processing. The determination function 233 then identifies representative values ​​and standard deviations of CT values ​​for specific regions corresponding to 70keV from monochromatic image data 90a corresponding to 70keV. Furthermore, the determination function 233 identifies representative values ​​and standard deviations of CT values ​​for specific regions corresponding to 35keV from monochromatic image data 90b corresponding to 35keV.

[0109] Therefore, according to the workstation 2 of this embodiment, in addition to the same effects as in the first embodiment, even if the memory circuit 22 does not pre-store the CT value database 22a, it is possible to display monochromatic image data 90b with an appropriate window width and window level in response to changes in the energy value to be displayed.

[0110] Furthermore, according to the workstation 2 of this embodiment, instead of using pre-stored representative values ​​and standard deviations of CT values, the appropriate window width and window level for displaying the monochromatic image data 90b are determined based on the representative values ​​and standard deviations of CT values ​​of a specific region actually obtained from the monochromatic image data 90a and 90b to be displayed. This enables highly accurate adjustment of the window width and window level in accordance with the actual CT values.

[0111] (Third embodiment) In the first embodiment described above, the values ​​of the coefficients α and β used to calculate the window width and window level were pre-stored in the memory circuit 22 as coefficient information 22b. In contrast, the workstation 2 of this embodiment outputs the values ​​of the coefficients α and β using the first trained model.

[0112] The medical image processing system S of this embodiment comprises an X-ray CT scanner 1, a workstation 2, and a medical image storage device 3, similar to the first embodiment. The configurations of the X-ray CT scanner 1 and the medical image storage device 3 are the same as in the first embodiment.

[0113] Furthermore, the workstation 2 of this embodiment includes a network interface 21, a memory circuit 22, a processing circuit 23, an input interface 24, and a display 25, similar to the first embodiment.

[0114] The processing circuit 23 of the workstation 2 in this embodiment includes an acquisition function 231, a reception function 232, a determination function 233, and a display control function 234, similar to the first embodiment.

[0115] The acquisition function 231, the reception function 232, and the display control function 234 have the same functions as in the first embodiment.

[0116] In addition to the same functions as in the first embodiment, the determination function 233 of this embodiment causes the first trained model to output coefficients α and β, and inputs the output coefficients α and β into equations (1) and (2) similar to those in the first embodiment to determine the window width and window level for displaying monochromatic image data 90b corresponding to the energy value specified by the user's modification operation.

[0117] The first trained model outputs the coefficient α in equation (1) and the coefficient β in equation (2). The first trained model is an AI (Artificial Intelligence) model generated by deep learning or other machine learning. The first trained model is, for example, a model that has been trained by associating the window width and window level of the energy value before modification and the Monochromatic image data 90a corresponding to that energy value with the window width and window level that can appropriately display the energy value after modification and the Monochromatic image data 90b corresponding to that energy value, and the representative value of the CT value of a specific region and the standard deviation of the CT value of the specific region in the Monochromatic image data 90a and 90b before and after modification. Note that the window width and window level that can appropriately display each of the Monochromatic image data 90 may be, for example, the window width and window level manually adjusted by the user. The training method and training data of the first trained model are not limited to these examples.

[0118] For example, the decision function 233 may obtain coefficients α and β from the first trained model by inputting the original energy value (e.g., 70 keV), the modified energy value selected by the user (e.g., 35 keV), and the window width and window level of the original monochromatic image data 90a into the first trained model.

[0119] Furthermore, the determination function 233 obtains the information to be input to equations (1) and (2), other than the coefficients α and β, from the CT value database 22a stored in the memory circuit 22 and the window width and window level of the monochromatic image data 90a currently displayed on the display 25, similar to the first embodiment.

[0120] The first trained model may be incorporated into the decision function 233. Alternatively, the first trained model may be stored in the memory circuit 22 and accessed by the decision function 233.

[0121] According to the workstation 2 of this embodiment, in addition to the same effects as the first embodiment, by providing a first trained model that outputs coefficient α in equation (1) and coefficient β in equation (2), it may be possible to determine a more appropriate window width and window level by using coefficients α and β that have been stored in advance as fixed values. For example, even if the image quality of the monochromatic image data 90 changes due to changes in imaging conditions or imaging technique, and the required display mode changes, optimization based on new training data can be performed by retraining the first trained model.

[0122] In this embodiment, the workstation 2 may acquire a first pre-trained model that has been trained externally in advance, or the workstation 2's processing circuit 23 may be equipped with a learning function that trains the first pre-trained model. The learning function is an example of a learning unit.

[0123] (Fourth embodiment) In the third embodiment described above, the values ​​of the coefficients α and β used to calculate the window width and window level were output by the first trained model. In contrast, in this fourth embodiment, the workstation 2 causes the second trained model to output the window width and window level for displaying the monochromatic image data 90b corresponding to the energy value specified by the user's modification operation.

[0124] The medical image processing system S of this embodiment comprises an X-ray CT scanner 1, a workstation 2, and a medical image storage device 3, similar to the first embodiment. The configurations of the X-ray CT scanner 1 and the medical image storage device 3 are the same as in the first embodiment.

[0125] Furthermore, the workstation 2 of this embodiment includes a network interface 21, a memory circuit 22, a processing circuit 23, an input interface 24, and a display 25, similar to the first embodiment.

[0126] The processing circuit 23 of the workstation 2 in this embodiment includes an acquisition function 231, a reception function 232, a determination function 233, and a display control function 234, similar to the first embodiment.

[0127] The acquisition function 231, the reception function 232, and the display control function 234 have the same functions as in the first embodiment.

[0128] In addition to the same functions as in the first embodiment, the determination function 233 of this embodiment causes the second trained model to output a window width and window level for displaying monochromatic image data 90b corresponding to the energy value specified by the user's modification operation.

[0129] The second trained model receives inputs such as the energy value before the change, the window width and window level of the Monochromatic image data 90a corresponding to that energy value, a representative value of the CT value of a specific region corresponding to the energy value before and after the change, and the standard deviation of the CT value of a specific region corresponding to the energy value before and after the change, and outputs a window width and window level that allows the Monochromatic image data 90b corresponding to the energy value after the change to be displayed appropriately.

[0130] The second pre-trained model is an AI model generated by deep learning or other machine learning methods. For example, the second pre-trained model is a model trained by associating the window width and window level of the original energy value and the corresponding Monochromatic image data 90a with the window width and window level that allows the modified energy value and the corresponding Monochromatic image data 90b to be displayed appropriately, as well as the representative value of the CT value in a specific region of the Monochromatic image data 90a and 90b before and after the modification, and the standard deviation of the CT value in that specific region. The training method and training data for the second pre-trained model are not limited to these examples.

[0131] For example, the decision function 233 may input the original energy value (e.g., 70 keV), the modified energy value selected by the user (e.g., 35 keV), and the window width and window level of the original monochromatic image data 90a into a second trained model, thereby obtaining a window width and window level suitable for displaying the monochromatic image data 90b corresponding to the modified energy value (e.g., 35 keV) from the second trained model.

[0132] According to the workstation 2 of this embodiment, in addition to the same effects as in the first embodiment, the modified window width and window level can be directly obtained by the second trained model.

[0133] Similar to the third embodiment, the workstation 2 of this embodiment may acquire a second pre-trained model that has been trained externally in advance, or the processing circuit 23 of the workstation 2 may be equipped with a learning function that trains the second pre-trained model. The learning function is an example of a learning unit.

[0134] (Fifth embodiment) In the first to fourth embodiments described above, the workstation 2 performed image display processing, including automatic window width and window level adjustment. However, this processing may be performed by the X-ray CT apparatus 1 or other devices. Examples of other devices include, for example, an information processing terminal such as a radiologist's work PC. An information processing terminal such as a radiologist's work PC may be an example of an image processing device.

[0135] Furthermore, when the X-ray CT apparatus 1 performs image display processing including automatic window width and window level adjustment, for example, the processing circuit 44 of the X-ray CT apparatus 1 may, in addition to the configuration shown in Figure 2, further include the reception function 232, the determination function 233, and the display control function 234, which were described as functions of the processing circuit 23 of the workstation 2 in the first embodiment. In this case, the X-ray CT apparatus 1 may be an example of an image processing apparatus.

[0136] (modified version) In the embodiments described above, monochromatic image data 90 was given as an example of CT image data to be displayed, but the CT image data to be displayed is not limited to this. For example, when displaying multiple CT image data obtained by different tube voltages using a single energy (Single Energy) system with a conventional X-ray CT system other than a DECT system or PCCT system, the window width and window level determination method described in the embodiments described above may be used.

[0137] Furthermore, although the above embodiments targeted reconstructed CT image data, the methods for determining the window width and window level described in the above embodiments may also be applied to projection data before reconstruction in order to determine the reconstruction function.

[0138] Furthermore, although only the change in energy value was described as an example in each of the embodiments described above, conditions other than the energy value may also be changed. For example, if any of the image acquisition conditions, image generation conditions, or acquired image information are changed, the determination function 233 of the workstation 2 may determine an appropriate window width and window level for displaying the CT image data after the changes in these conditions, using the methods described in each of the embodiments described above.

[0139] Furthermore, while the above embodiments described an example of changing the display target from Monochromatic image data 90a corresponding to a high energy value (e.g., 70 keV) to Monochromatic image data 90b corresponding to a low energy value (e.g., 35 keV), the methods of the above embodiments are also applicable when changing the display target from Monochromatic image data 90b corresponding to a low energy value to Monochromatic image data 90a corresponding to a high energy value.

[0140] Furthermore, while 35 keV and 70 keV were given as examples of multiple energy values ​​in each of the embodiments described above, the energy values ​​are not limited to these. Also, the displayable monochromatic image data 90 are not limited to two types.

[0141] The various types of data discussed in this specification are typically digital data.

[0142] According to at least one embodiment described above, X-ray CT image data can be displayed with an appropriate window width and window level in response to changes in the energy value to be displayed.

[0143] While several embodiments have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be implemented in a variety of other forms, and various omissions, substitutions, modifications, and combinations of embodiments are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0144] With respect to the above embodiments, the following additional notes are disclosed as aspects of the invention and selective features.

[0145] (Note 1) A display control unit that displays first CT image data, shown at a first keV value, on a display unit with a first window width and first window level, The system includes a determination unit that determines a second window width and a second window level different from the first window width and the first window level based on the first window width, the first window level, the CT value of a specific region corresponding to the first keV value, the CT value of the specific region corresponding to a second keV value different from the first keV value, and statistical information relating to the CT value of the specific region corresponding to the first keV value and statistical information relating to the CT value of the specific region corresponding to the second keV value. The display control unit causes the display unit to display the second CT image data of the second keV value at the determined second window width and second window level. Image processing device.

[0146] (Note 2) The image processing device may further include a receiving unit that receives a user's change operation to change the display target from the first CT image data to the second CT image data. The determination unit may determine the second window width and the second window level when the reception unit receives the user's change operation. The display control unit may, when the reception unit receives the user's change operation, cause the display unit to display the second CT image data on the display unit at the determined second window width and second window level.

[0147] (Note 3) The image processing device may include a storage unit that stores a representative value of the CT value of the specific region corresponding to the first keV value, statistical information relating to the CT of the specific region corresponding to the first keV value, a representative value of the CT value of the specific region corresponding to the second keV value, and statistical information relating to the CT value of the specific region corresponding to the second keV value. The determination unit may determine the second window width and the second window level based on a representative value of the CT value of the specific region corresponding to the first keV value stored in the storage unit, statistical information relating to the CT value of the specific region corresponding to the first keV value, a representative value of the CT value of the specific region corresponding to the second keV value, and statistical information relating to the CT value of the specific region corresponding to the second keV value.

[0148] (Note 4) The determination unit may identify a representative value of the CT value of the specific region corresponding to the first keV value and statistical information relating to the CT value of the specific region corresponding to the first keV value from the first CT image data, and identify a representative value of the CT value of the specific region corresponding to the second keV value and statistical information relating to the CT value of the specific region corresponding to the second keV value from the second CT image data.

[0149] (Note 5) The aforementioned specific region may be a fatty region, or a region in which any organ specified by the user or examination order is visualized.

[0150] (Note 6) The first CT image data and the second CT image data may be monochromatic image data obtained from the same scan of the subject.

[0151] (Note 7) The aforementioned statistical information regarding the CT value may also be the standard deviation of the CT value.

[0152] (Note 8) The determination unit may calculate the second window width using the following formula (1) and the second window level using the following formula (2). The second window width = the first window width + (the difference between the standard deviation of the CT value of the specific region corresponding to the second keV value and the standard deviation of the CT value of the specific region corresponding to the first keV value) × α...(1) Second window level = First window level + (Difference between the CT value of the specific region corresponding to the second keV value and the CT value of the specific region corresponding to the first keV value) × β···(2)

[0153] (Note 9) The image processing device may include a first trained model that outputs the coefficient α in equation (1) and the coefficient β in equation (2). The determination unit may read the coefficients α and β output from the first trained model and input them into equations (1) and (2).

[0154] (Note 10) The image processing device may include a second trained model that receives input of the first window width, the first window level, the CT value of the specific region corresponding to the first keV value, the CT value of the specific region corresponding to the second keV value, and statistical information relating to the CT value of the specific region corresponding to the first keV value and statistical information relating to the CT value of the specific region corresponding to the second keV value, and outputs the second window width and the second window level. The determination unit may determine the second window width and the second window level using the second trained model.

[0155] (Note 11) A first display control step involves displaying first CT image data, shown at a first keV value, on a display unit with a first window width and a first window level. A determination step in which a second window width and a second window level different from the first window width and the first window level are determined based on the first window width, the first window level, the CT value of a specific region corresponding to the first keV value, the CT value of the specific region corresponding to a second keV value different from the first keV value, and statistical information relating to the CT value of the specific region corresponding to the first keV value and statistical information relating to the CT value of the specific region corresponding to the second keV value, A second display control step involves causing the display unit to display the second CT image data of the second keV value at the determined second window width and second window level, Image processing methods including [specific details omitted].

[0156] (Note 12) A first display control step involves displaying first CT image data, shown at a first keV value, on a display unit with a first window width and a first window level. A determination step in which a second window width and a second window level different from the first window width and the first window level are determined based on the first window width, the first window level, the CT value of a specific region corresponding to the first keV value, the CT value of the specific region corresponding to a second keV value different from the first keV value, and statistical information relating to the CT value of the specific region corresponding to the first keV value and statistical information relating to the CT value of the specific region corresponding to the second keV value, A second display control step involves causing the display unit to display the second CT image data of the second keV value at the determined second window width and second window level, A program that causes a computer to execute something. [Explanation of symbols]

[0157] 1 X-ray CT device 2 Workstations 3. Medical image storage device 10. Mounting device 11 X-ray tube 12 X-ray detectors 13 rotation frames 14 X-ray high-voltage equipment 15 Control device 16 Wedge 17 Collimator 18 DAS 21,45 Network Interfaces 22 Memory circuit 22a CT Value Database 22b Coefficient Information 23,44 Processing Circuits 24,43 Input Interfaces 25,42 displays 30 Bed equipment 31 base 32 Bed drive mechanism 33 Top plate 34. Tabletop support frame 90,90a,90b,91a,91b Monochromatic image data 40 Console device 41 memory 81 Slide bar 200 Image storage device 231 Acquisition function 232 Reception function 233 Decision Function 234 Display control function 441 Control Functions 442 Pre-processing function 443 Reconfiguration function 444 Image Processing Functions 445 Transmission function N Network P Subject S Medical Image Processing System

Claims

1. A display control unit that displays first CT image data, which is displayed at a first keV value, on a display unit with a first window width and a first window level, The system includes a determination unit that determines a second window width and a second window level different from the first window width and the first window level based on the first window width, the first window level, the CT value of a specific region corresponding to the first keV value, the CT value of the specific region corresponding to a second keV value different from the first keV value, and statistical information relating to the CT value of the specific region corresponding to the first keV value and statistical information relating to the CT value of the specific region corresponding to the second keV value. The display control unit causes the display unit to display the second CT image data of the second keV value at the determined second window width and second window level. Image processing device.

2. The system further includes a reception unit that receives a user's change operation to change the display target from the first CT image data to the second CT image data, The determination unit determines the second window width and the second window level when the reception unit receives the user's change operation. When the reception unit receives the user's change operation, the display control unit causes the display unit to display the second CT image data at the determined second window width and second window level. The image processing apparatus according to claim 1.

3. The system includes a storage unit that stores a representative value of the CT value of the specific region corresponding to the first keV value, statistical information relating to the CT of the specific region corresponding to the first keV value, a representative value of the CT value of the specific region corresponding to the second keV value, and statistical information relating to the CT value of the specific region corresponding to the second keV value. The determination unit determines the second window width and the second window level based on the representative value of the CT value of the specific region corresponding to the first keV value stored in the storage unit, statistical information relating to the CT value of the specific region corresponding to the first keV value, the representative value of the CT value of the specific region corresponding to the second keV value, and statistical information relating to the CT value of the specific region corresponding to the second keV value. The image processing apparatus according to claim 1.

4. The determination unit identifies a representative value of the CT value of the specific region corresponding to the first keV value and statistical information relating to the CT value of the specific region corresponding to the first keV value from the first CT image data, and identifies a representative value of the CT value of the specific region corresponding to the second keV value and statistical information relating to the CT value of the specific region corresponding to the second keV value from the second CT image data. The image processing apparatus according to claim 1.

5. The aforementioned specific region is a fatty region, or a region in which any organ specified by the user or examination order is visualized. The image processing apparatus according to claim 1.

6. The first CT image data and the second CT image data are monochromatic image data obtained from the same scan of the subject. The image processing apparatus according to claim 1.

7. The aforementioned statistical information regarding CT values ​​is the standard deviation of CT values. The image processing apparatus according to any one of claims 1 to 6.

8. The determination unit calculates the second window width using the following formula (1) and calculates the second window level using the following formula (2). The second window width = the first window width + (the difference between the standard deviation of the CT value in the specific region corresponding to the second keV value and the standard deviation of the CT value in the specific region corresponding to the first keV value) × α ... (1) Second window level = First window level + (Difference between the CT value of the specific region corresponding to the second keV value and the CT value of the specific region corresponding to the first keV value) × β ... (2) The image processing apparatus according to claim 7.

9. The system comprises a first trained model that outputs the coefficient α in equation (1) and the coefficient β in equation (2), The determination unit reads the coefficients α and β output from the first trained model and inputs them into equations (1) and (2). The image processing apparatus according to claim 8.

10. The system includes a second trained model that receives input of the first window width, the first window level, the CT value of the specific region corresponding to the first keV value, the CT value of the specific region corresponding to the second keV value, and statistical information relating to the CT value of the specific region corresponding to the first keV value and statistical information relating to the CT value of the specific region corresponding to the second keV value, and outputs the second window width and the second window level. The determination unit determines the second window width and the second window level using the second trained model. The image processing apparatus according to claim 1.

11. A first display control step involves displaying first CT image data, which is displayed at a first keV value, on a display unit with a first window width and a first window level. A determination step of determining a second window width and a second window level different from the first window width and the first window level based on the first window width, the first window level, the CT value of a specific region corresponding to the first keV value, the CT value of the specific region corresponding to a second keV value different from the first keV value, and statistical information relating to the CT value of the specific region corresponding to the first keV value and statistical information relating to the CT value of the specific region corresponding to the second keV value, A second display control step involves causing the display unit to display the second CT image data of the second keV value at the determined second window width and second window level, Image processing methods including [specific details omitted].

12. A first display control step involves displaying first CT image data, which is displayed at a first keV value, on a display unit with a first window width and a first window level. A determination step of determining a second window width and a second window level different from the first window width and the first window level based on the first window width, the first window level, the CT value of a specific region corresponding to the first keV value, the CT value of the specific region corresponding to a second keV value different from the first keV value, and statistical information relating to the CT value of the specific region corresponding to the first keV value and statistical information relating to the CT value of the specific region corresponding to the second keV value, A second display control step involves causing the display unit to display the second CT image data of the second keV value at the determined second window width and second window level, A program that causes a computer to execute something.

Images