X-ray diagnostic equipment, medical information processing device and program

Abstract

To appropriately evaluate time-series variation of the state of an analyte's bone.SOLUTION: An x-ray diagnostic apparatus according to an embodiment comprises a calculation unit and a display control unit. The calculation unit calculates an error of an index value for evaluating the state of an analyte's bone, on the basis of at least one of a photographic image and a photographing condition of the analyte corresponding to x-rays of two different types of energies. The display control unit causes information based on the calculated error of the index value to be displayed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The embodiments disclosed in the present specification and drawings are directed to an X-ray diagnostic apparatus. 、 Medical information processing device and programs Regarding. [Background technology]

[0002] Dual-energy X-ray absorptiometry (DXA) is a conventional technique for measuring bone condition indicators such as bone mineral density (BMD) and bone mineral content (BMC). DXA uses image data of a subject's body corresponding to two different energy levels of X-rays to distinguish between bone and soft tissue, and then calculates bone mineral density and bone mineral content.

[0003] Dedicated X-ray diagnostic equipment (hereafter referred to as "dedicated equipment") is known as a device for measuring indicators of bone condition. Dedicated equipment reduces the influence of scattered rays by taking images while sequentially moving a thin, rectangular X-ray irradiation area in the direction of the short side of the X-ray irradiation area. In recent years, bone density and bone mineral content have also been measured using the DXA method in non-dedicated X-ray diagnostic equipment (hereafter referred to as "general-purpose equipment").

[0004] Although the above-mentioned dedicated and general-purpose machines display bone density and bone mineral content, such displays do not allow for proper evaluation of time-series changes in bone density and bone mineral content. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-192054 [Non-patent literature]

[0006] [Non-Patent Document 1] "Proximal femoral BMD measurement manual," [Retrieved March 1, 2021], Internet<http: / / www.josteo.com / ja / guideline / doc / 4_1.pdf> Summary of the Invention [Problem to be solved by the invention]

[0007] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to be able to appropriately evaluate time-series changes in the bone condition of a subject. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described below can also be positioned as other problems. [Means for solving the problem]

[0008] An X-ray diagnostic apparatus according to an embodiment includes a calculation unit and a display control unit. The calculation unit calculates an error in an index value for evaluating a bone condition of a subject based on at least one of an image of the subject corresponding to X-rays of two different energies and imaging conditions. The display control unit displays information based on the calculated error in the index value. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of an X-ray diagnostic apparatus according to the first embodiment. [Figure 2] FIG. 2 is a flowchart showing an outline of a processing procedure performed by the X-ray diagnostic apparatus according to the first embodiment. [Figure 3] FIG. 3 is a flowchart showing a processing procedure by the calculation function and the control function according to the first embodiment. [Figure 4] FIG. 4 is a diagram for explaining an example of processing by the calculation function according to the first embodiment. [Figure 5] FIG. 5 is a diagram showing an example of information displayed by the control function according to the first embodiment. [Figure 6] FIG. 6 is a diagram showing an example of information displayed by the control function according to the first embodiment. [Figure 7] FIG. 7 is a flowchart showing a processing procedure by the calculation function and the control function according to the second embodiment. [Figure 8] FIG. 8 is a diagram showing an example of information displayed by the control function according to the second embodiment. [Figure 9] FIG. 9 is a diagram showing an example of information displayed by the control function according to the second embodiment. [Figure 10] FIG. 10 is a block diagram showing an example of the configuration of an X-ray diagnostic apparatus according to the third embodiment. [Figure 11] FIG. 11 is a diagram for explaining an example of processing by the calculation function and the control function according to another embodiment. [Figure 12] FIG. 12 is a block diagram showing an example of the configuration of a medical image processing apparatus according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of an X-ray diagnostic apparatus and a medical image processing apparatus will be described in detail with reference to the drawings. Note that the X-ray diagnostic apparatus and the medical image processing apparatus according to the present application are not limited to the embodiments shown below. In the following description, similar components will be given common reference numerals, and duplicated descriptions will be omitted.

[0011] (First embodiment) The configuration of an X-ray diagnostic apparatus according to the first embodiment will be described. The X-ray diagnostic apparatus according to this embodiment measures indices for evaluating bone condition by DXA. Indices for evaluating bone condition include BMD (bone mineral density) and BMC (bone mineral content). X-ray diagnostic apparatuses include dedicated machines for measuring bone condition as well as general-purpose machines such as X-ray TV apparatuses and general X-ray imaging apparatuses. In the first embodiment, a C-arm type X-ray TV apparatus, which is a general-purpose machine, will be described as an example.

[0012] Fig. 1 is a block diagram showing an example of the configuration of an X-ray diagnostic apparatus 1 according to the first embodiment. As shown in Fig. 1, the X-ray diagnostic apparatus 1 includes an X-ray high-voltage device 11, an X-ray tube 12, an X-ray aperture 13, a tabletop 14, a C-arm 15, an X-ray detector 16, a memory 17, a display 18, an input interface 19, and a processing circuit 20.

[0013] X-ray high voltage device 11 applies a high voltage to X-ray tube 12 under the control of processing circuit 20. For example, X-ray high voltage device 11 has electric circuits such as a transformer and a rectifier, and includes a high voltage generator that generates a high voltage to be applied to X-ray tube 12, and an X-ray control device that controls the output voltage according to the X-rays irradiated by X-ray tube 12. The high voltage generator may be of a transformer type or an inverter type.

[0014] The X-ray tube 12 is a vacuum tube having a cathode (filament) that generates thermoelectrons and an anode (target) that generates X-rays upon impact of the thermoelectrons. The X-ray tube 12 generates X-rays by irradiating thermoelectrons from the cathode to the anode using a high voltage applied from the X-ray high voltage device 11.

[0015] The X-ray aperture 13 has an X-ray aperture that narrows the irradiation range of the X-rays generated by the X-ray tube 12 and a filter that adjusts the X-rays emitted from the X-ray tube 12.

[0016] The X-ray aperture in the X-ray aperture 13 has, for example, four slidable aperture blades. By sliding the aperture blades, the X-ray aperture narrows the X-rays generated by the X-ray tube 12 and irradiates the subject P. Here, the aperture blades are plate-shaped members made of lead or the like, and are provided near the X-ray irradiation port of the X-ray tube 12 in order to adjust the X-ray irradiation range. Furthermore, the aperture blades may be formed so that opposing blades can move asymmetrically, or alternatively, the opposing blades may be formed so that only opposing blades can move symmetrically.

[0017] The filter in the X-ray aperture 13 changes the radiation quality of the transmitted X-rays depending on its material and thickness, in order to reduce the radiation dose to the subject P and improve the image quality of the X-ray image data, thereby reducing soft ray components that are easily absorbed by the subject P and high energy components that cause a decrease in contrast in the X-ray image data. In addition, the filter changes the X-ray dose and irradiation range depending on its material, thickness, position, etc., and attenuates the X-rays so that the X-rays irradiated from the X-ray tube 12 to the subject P have a predetermined distribution.

[0018] For example, the X-ray aperture 13 has a drive mechanism such as a motor, an actuator, etc., and controls the irradiation of X-rays by operating the drive mechanism under the control of the processing circuitry 20. For example, the X-ray aperture 13 applies a drive voltage to the drive mechanism in accordance with a control signal received from the processing circuitry 20, thereby adjusting the opening of the aperture blades of the X-ray aperture and controlling the irradiation range of the X-rays irradiated to the subject P. Furthermore, for example, the X-ray aperture 13 applies a drive voltage to the drive mechanism in accordance with a control signal received from the processing circuitry 20, thereby adjusting the position of the filter and controlling the distribution of the dose of X-rays irradiated to the subject P.

[0019] The top board 14 is a bed on which the subject P rests, and is placed on a couch (not shown). For example, the couch has a driving mechanism such as a motor, an actuator, etc., and the top board 14 is moved and tilted by operating the driving mechanism under the control of the processing circuitry 20.

[0020] The C-arm 15 holds the X-ray tube 12, the X-ray aperture 13, and the X-ray detector 16 so that they face each other across the subject P. For example, the C-arm 15 has a drive mechanism such as a motor, an actuator, etc., and applies a drive voltage to the drive mechanism in response to a control signal received from the processing circuitry 20, thereby rotating and moving the X-ray tube 12, the X-ray aperture 13, and the X-ray detector 16 relative to the subject P and controlling the X-ray irradiation position and irradiation angle.

[0021] The X-ray detector 16 is, for example, an X-ray flat panel detector (FPD) having detection elements arranged in a matrix. The X-ray detector 16 detects X-rays that are irradiated from the X-ray tube 12 and transmitted through the subject P, and outputs a detection signal corresponding to the detected X-ray dose to the processing circuitry 20. The X-ray detector 16 may be an indirect conversion type detector having a grid, a scintillator array, and a photosensor array, or may be a direct conversion type detector having semiconductor elements that convert incident X-rays into electrical signals.

[0022] The memory 17 is realized by, for example, a semiconductor memory element such as a RAM (Random Access Memory). The memory 17 temporarily stores the processing results by the processing circuitry 20. For example, the memory 17 receives and temporarily stores various data such as X-ray image data collected by the processing circuitry 20. Here, the X-ray image data in this application includes detection signals detected by the X-ray detector 16, projection data generated based on the detection signals, and X-ray images generated based on the projection data. The memory 17 also stores programs corresponding to various functions that are read out and executed by the processing circuitry 20.

[0023] The display 18 displays various types of information. For example, under the control of the processing circuitry 20, the display 18 displays a GUI for receiving instructions from an operator and various X-ray images. The display 18 also displays the results of processing by the processing circuitry 20. For example, the display 18 displays the measured values ​​of indices for evaluating the bone condition of the subject P (bone density and bone mineral content), errors in the measured values, etc.

[0024] The input interface 19 accepts various input operations from an operator, converts the accepted input operations into electrical signals, and outputs the electrical signals to the processing circuit 20. For example, the input interface 19 may be implemented by a mouse, keyboard, trackball, switch, button, joystick, a touchpad that performs input operations by touching the operation surface, a touchscreen that integrates a display screen and a touchpad, a non-contact input circuit using an optical sensor, a voice input circuit, or the like. The input interface 19 may also be implemented by a tablet terminal or the like that is capable of wireless communication with the device main body. The input interface 19 is not limited to those that have physical operation components such as a mouse and 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 device and outputs the electrical signals to the processing circuit 20 is also included as an example of the input interface 19.

[0025] The processing circuitry 20 controls the overall operation of the X-ray diagnostic apparatus 1. The processing circuitry 20 also functions as an acquisition function 201, a control function 202, and a calculation function 203 by reading and executing a program stored in the memory 17. The control function 202 is an example of a display control unit. The calculation function 203 is an example of a calculation unit.

[0026] It is important to properly evaluate the time-series changes in the bone condition of the subject. However, when comparing the measured values ​​in the past examination with the measured values ​​in the current examination, it is not possible to grasp at a glance whether the time-series changes can be said to be significant or not, and it is not possible to properly evaluate the time-series changes in the bone condition of the subject, simply by displaying the measured index values.

[0027] The X-ray diagnostic apparatus 1 configured as described above displays the error of the index value in addition to the index value used to evaluate the bone condition of the subject, thereby enabling appropriate evaluation of time-series changes in the bone condition of the subject.

[0028] The processing executed by the X-ray diagnostic apparatus 1 will be described below with reference to Fig. 2. Fig. 2 is a flowchart showing an outline of the processing procedure executed by the X-ray diagnostic apparatus 1.

[0029] The acquisition function 201 determines the X-ray conditions for dual energy imaging. For example, the acquisition function 201 determines the X-ray conditions input from the input interface 19 and the X-ray conditions stored in the memory 17 (for example, set at the time of the previous examination) as the X-ray conditions for imaging. When an operator issues an instruction to perform imaging via the input interface 19, the acquisition function 201 performs dual energy imaging according to the determined X-ray conditions.

[0030] The acquisition function 201 can also determine the X-ray conditions for dual-energy imaging based on positioning by fluoroscopy. In such a case, the acquisition function 201 first sequentially acquires fluoroscopic images for positioning in response to an operator's fluoroscopic execution operation. Here, the acquisition function 201 performs ABC (Automatic Brightness Control) control, for example, by comparing the average pixel value of the acquired fluoroscopic images with a threshold value and feeding back the comparison result to the X-ray conditions for the next fluoroscopic image.

[0031] Then, when the X-ray conditions have reached a stable state through ABC control, the acquisition function 201 stores the body thickness information based on the X-ray conditions in the memory 17 as "information on body thickness" of the subject, and determines the X-ray conditions for dual energy imaging (imaging using two different tube voltages) based on the "information on body thickness." Note that the X-ray conditions for dual energy imaging may be determined based on the X-ray conditions that have reached a stable state through ABC control. When the operator issues an instruction to perform imaging, the acquisition function 201 executes imaging according to the determined X-ray conditions (step S101).

[0032] For example, the acquisition function 201 performs imaging of a region including an ROI (Region of Interest) such as the lumbar vertebrae or the proximal femur using a first tube voltage (high voltage) and acquires X-ray image data corresponding to the first tube voltage. The acquisition function 201 also performs imaging of the same region including the ROI using a second tube voltage (low voltage) and acquires X-ray image data corresponding to the second tube voltage.

[0033] Note that the imaging for collecting images of a subject corresponding to X-rays of two different energies is not limited to the dual energy imaging described above. For example, imaging may be performed by irradiating a subject with X-rays of continuous energy once using a two-layer detector that splits X-ray energy continuous into X-rays of low energy and X-rays of high energy.

[0034] When the collection function 201 executes imaging, the calculation function 203 calculates index values ​​for evaluating the bone condition of the subject from the two types of X-ray image data collected by dual-energy imaging. The control function 202 displays the calculated index values ​​(e.g., bone density, bone mineral content, etc.) (step S102). For example, the calculation function 203 generates a bone image based on the two types of X-ray image data and measures the bone density, bone mineral content, etc. in the region of interest of the generated bone image. The control function 202 displays the measured bone density, bone mineral content, etc. on the display 18.

[0035] In step S102, the calculation function 203 calculates the error of the calculated index value (bone density, bone mineral content, etc.). The control function 202 displays the error of the calculated index value (bone density, bone mineral content, etc.).

[0036] An example of the process in step S102 will be described below with reference to Fig. 3. Here, the BMD (bone mineral density) will be used as an example of an index for evaluating the bone condition of the subject.

[0037] The calculation function 203 generates a bone image from two types of X-ray image data collected by dual-energy imaging, and also sets an ROI for the generated bone image (step S201).

[0038] The calculation function 203 may set an ROI specified by an operator. Alternatively, the calculation function 203 may set an ROI extracted from a bone image as a result of an existing segmentation process. The X-ray image data for which the ROI is set by the calculation function 203 may be any of a high-kV image acquired by imaging with a first tube voltage (high voltage), a low-kV image acquired by imaging with a second tube voltage (low voltage), or a bone-enhanced image (described later). Using a high-kV image or a bone-enhanced image in which bone regions are more clearly shown allows for more accurate setting of the ROI. Furthermore, when a bone-enhanced image is used, a material decomposition process (described later) is performed before setting the ROI.

[0039] Next, the calculation function 203 measures bone density based on the projection data (high kV image) collected by imaging with the first tube voltage (high voltage) and the projection data (low kV image) collected by imaging with the second tube voltage (low voltage) (step S202).

[0040] Specifically, the calculation function 203 obtains the distribution of linear attenuation coefficients for each of the two types of projection data, and solves simultaneous equations consisting of the linear attenuation coefficients and mixing amounts of two materials (bone and non-bone (soft tissue)) for each position (each pixel) of the distribution of linear attenuation coefficients to calculate the mixing amounts and mixing ratios of the two materials at each position. Furthermore, the calculation function 203 generates two types of projection data corresponding to bone and soft tissue, respectively, based on the mixing amounts of bone and soft tissue at each position. The projection data generated by the collection function 201 is stored in the memory 17.

[0041] Furthermore, the calculation function 203 calculates the densities of two materials (bone and non-bone (soft tissue)) at each position (each pixel) by solving simultaneous equations consisting of the mass attenuation coefficients and densities of two materials. For example, the calculation function 203 calculates the bone mineral density (BMD) in the ROI. m ) is calculated.

[0042] The calculation function 203 calculates the error of the index value (bone density) based on at least one of the photographed images of the subject corresponding to X-rays of two different energies and the photographing conditions. Here, the calculation function 203 calculates the error of the measured value of bone density obtained in a single DXA photograph or a single photograph using a two-layer detector. Note that the error of bone density according to the first embodiment includes an error caused by scattered rays contained in the photographed image and an error caused by quantum noise, etc.

[0043] An example of calculating the error of the index value (bone density) based on the captured image and the imaging conditions will be described below. The imaging conditions include the X-ray conditions (including the tube voltage, tube current, pulse width, etc.) for a single DXA imaging (or a single imaging using a two-layer detector), the geometric imaging conditions, and information on the body thickness of the subject.

[0044] (Errors caused by scattered radiation) The calculation function 203 calculates the error caused by the scattered radiation contained in the captured image (step S203). The error caused by the scattered radiation contained in the captured image is calculated as the difference between the bone density measured based on the image in which the scattered radiation is not reduced (original image) and the bone density measured based on the image in which the scattered radiation is reduced, as shown in Fig. 4.

[0045] More specifically, the calculation function 203 acquires a scattered ray image (high kV scattered ray image) for X-ray image data (high kV image) corresponding to a first tube voltage (high voltage) and a scattered ray image (low kV scattered ray image) for X-ray image data (low kV image) corresponding to a second tube voltage (low voltage). The scattered ray image is acquired by acquiring the scattered ray amount (scattered ray image) for each pixel based on the X-ray conditions (kV and mAs), geometric imaging conditions, and information related to the body thickness of the subject.

[0046] Geometric imaging conditions include the position information of the aperture blades, the Source to Image Receptor Distance (SID), the Source to Object Distance (SOD) (or the distance between the detector and the top plate), etc. For example, if the aperture blades can move asymmetrically, the position information of the aperture blades is expressed by four parameters. Also, if the aperture blades can only move symmetrically, the position information of the aperture blades is expressed by two parameters. The geometric imaging conditions for imaging are recorded in the DICOM tags of the captured high-kV and / or low-kV images.

[0047] Furthermore, information regarding the subject's body thickness may be obtained using "information regarding body thickness" acquired by ABC control, or may be calculated using X-ray image data collected by dual energy imaging.

[0048] The memory 17 stores in advance scattered radiation data indicating the relationship between scattered radiation and, for example, X-ray conditions, geometric imaging conditions, and body thickness. The calculation function 203 estimates the amount of scattered radiation for each dual-energy imaging based on the scattered radiation data, and acquires a "high-kV scattered radiation image" and a "low-kV scattered radiation image," respectively. The calculation function 203 estimates the "high-kV scattered radiation image" shown in FIG. 4 based on the X-ray conditions, geometric imaging conditions, and information related to the subject's body thickness for high-voltage imaging. Similarly, the calculation function 203 estimates the "low-kV scattered radiation image" shown in FIG. 4 based on the X-ray conditions, geometric imaging conditions, and information related to the subject's body thickness for low-voltage imaging.

[0049] Then, calculation function 203 generates each difference image (high-kV difference image, low-kV difference image) by excluding the high-kV scattered radiation image from the high-kV image and excluding the low-kV scattered radiation image from the low-kV image. Calculation function 203 sets an ROI based on the position and size of the ROI set in step S201 for the bone image (image with reduced scattered radiation) generated from each difference image, and calculates bone density in the set ROI. Calculation function 203 calculates the difference between the bone density in the ROI of the image with no scattered radiation reduction and the bone density in the ROI of the image with no scattered radiation reduction as an error caused by scattered radiation contained in the captured image.

[0050] (Errors caused by quantum noise, etc.) Returning to Fig. 3, after calculating the error due to scattered rays as described above, the calculation function 203 determines the error in the measurement value due to quantum noise, etc. (step S204). Errors due to quantum noise, etc. include errors due to quantum noise and circuit noise. The error due to quantum noise is an error due to X-ray variations that occur stochastically in the X-ray irradiation path, and the error due to circuit noise is an error due to operational variations that occur stochastically in the circuit included in the X-ray diagnostic apparatus 1.

[0051] The calculation function 203 calculates a value for evaluating the variation of values ​​based on the captured image as the error of the measurement value. For example, the calculation function 203 may calculate statistical information such as the standard deviation or variance of the bone density measured for each ROI (e.g., vertebral body) set in the captured image as the error caused by quantum noise or the like.

[0052] Furthermore, the calculation function 203 may calculate the sum of the quantum noise amount and the circuit noise amount as the error due to quantum noise, etc. For example, the calculation function 203 obtains the number of photons in an X-ray image based on the pixel values ​​of the X-ray image (e.g., a high kV image or a low kV image collected by dual energy imaging) and the amount of circuit noise, and estimates the amount of quantum noise based on the number of photons. The amount of circuit noise is calculated based on a signal acquired without X-ray irradiation.

[0053] Furthermore, the calculation function 203 may calculate the amount of quantum noise based on the bone-enhanced image and the soft-tissue-enhanced image generated based on the material decomposition process as an error caused by quantum noise, etc. For example, the calculation function 203 obtains the number of photons incident on each pixel by a simulation using the bone-enhanced image and the soft-tissue-enhanced image, and estimates the amount of quantum noise based on the number of photons.

[0054] In this way, in response to the calculation of the error due to quantum noise or the like, the control function 202 displays information based on the calculated error of the index value. For example, the control function 202 displays the measurement value of bone mineral density together with the error on the display 18 (step S205). The error includes an error due to scattered rays contained in the captured image and an error due to quantum noise or the like.

[0055] 5 is a diagram showing an example of information displayed on the display 18. The vertical axis indicates bone mineral density (BMD), and the horizontal axis indicates the examination date.

[0056] For example, the control function 202 displays the bone density measurement values ​​for "Date: a" and "Date: b," as well as an error bar that takes into account at least one of "error due to scattered radiation" and "error due to quantum noise, etc." The higher side of the error bar relative to the measurement value includes "error due to scattered radiation," since the bone density is underestimated due to the inclusion of scattered radiation. Furthermore, the higher and lower sides of the error bar relative to the measurement value include "error due to quantum noise, etc." Note that the information based on the error of the index value displayed by the control function 202 is not limited to the information indicating the error value described above, but may also be information derived based on the error. For example, the control function 202 may compare the calculated error with a reference error value and display the comparison result (e.g., the error exceeds the reference value).

[0057] The error when the conditions for estimating the error in the measurement value are changed may be displayed. An example of calculating the error in the index value (bone density) based on the imaging conditions will be described below. In such a case, the calculation function 203 calculates the error in the measurement value when the geometric imaging conditions are changed. Specifically, the calculation function 203 calculates the error in the bone density measurement value based on the geometric imaging conditions in the imaging conditions. For example, the calculation function 203 estimates the amount of scattered radiation incident on the ROI based on the geometric imaging conditions, and estimates the error in the measurement value based on the estimated amount of scattered radiation. As an example, the calculation function 203 calculates the "error caused by scattered radiation" when conditions such as the position information of the aperture blades, SID, and SOD are changed. The control function 202 displays the error in the measurement value when the geometric imaging conditions are changed.

[0058] FIG. 6 is a diagram showing an example of information displayed on the display 18 when the geometrical shooting conditions are changed, and shows a case in which the error in the measurement value is displayed when the geometrical shooting conditions at "Date: b" in FIG. 5 are changed.

[0059] For example, the control function 202 displays the error in the measurement value when the geometrical imaging conditions are changed (error bar indicated by a dotted line) alongside the display of the measurement value and error for "Date: b." The manner in which the error in the measurement value simulating the case where the geometrical imaging conditions are changed is not limited to the example shown in FIG. 6, and various other manners are possible. For example, the control function 202 can display an error bar in a different color or shape superimposed on the measurement value so that it can be distinguished from the error based on the actual conditions. The control function 202 can also display it in a separate window together with the GUI for changing the geometrical imaging conditions.

[0060] In the above-described embodiment, a case where bone density is used as an index value for evaluating the bone condition of a subject has been described, but the embodiment is not limited to this, and bone mineral content may also be used as an index value for evaluating the bone condition of a subject.

[0061] As described above, according to the first embodiment, the calculation function 203 calculates the error in the index value for evaluating the bone condition of the subject based on at least one of the photographed images of the subject corresponding to X-rays of two different energies and the photographing conditions. The control function 202 displays information based on the calculated error in the index value. Therefore, the X-ray diagnostic apparatus 1 according to the first embodiment can display the error in the measurement value for each examination in the examination of bone density and bone mineral content, making it possible to appropriately evaluate the time-series changes in the bone condition of the subject.

[0062] Furthermore, according to the first embodiment, the calculation function 203 calculates the error of the index value for evaluating the bone condition of the subject based on the geometric imaging conditions in the imaging conditions. Therefore, the X-ray diagnostic apparatus 1 according to the first embodiment makes it possible to accurately estimate the error even when the measurement values ​​of bone density and bone mineral content are calculated using a general-purpose machine that can change the geometric imaging conditions in various ways.

[0063] For example, when a bone density / bone mineral content test is performed using a general-purpose machine, the amount of scattered radiation incident on the ROI changes depending on the geometric imaging conditions (aperture blade opening, SID, SOD, etc.), which causes the amount of error in the measurement value to change. The X-ray diagnostic apparatus 1 according to the first embodiment can estimate the error based on the geometric imaging conditions, so it can accurately calculate the error even in measurements using such a general-purpose machine.

[0064] According to the first embodiment, the calculation function 203 calculates statistical information in the captured image as an error in an index value for evaluating the bone condition of the subject. Therefore, the X-ray diagnostic apparatus 1 according to the first embodiment makes it possible to calculate an error in a measurement value based on the captured image.

[0065] Furthermore, according to the first embodiment, the calculation function 203 estimates the amount of scattered radiation incident within the ROI based on the geometric imaging conditions, and estimates the error of the index value based on the estimated amount of scattered radiation. Therefore, the X-ray diagnostic apparatus 1 according to the first embodiment makes it possible to present the error of the index value taking into account the error due to scattered radiation.

[0066] Furthermore, according to the first embodiment, the calculation function 203 estimates an error including an error due to quantum noise. Therefore, the X-ray diagnostic apparatus 1 according to the first embodiment makes it possible to present an error in an index value that takes into account an error due to quantum noise.

[0067] Furthermore, according to the first embodiment, the calculation function 203 calculates the error in the index value when the geometrical imaging conditions are changed. The control function 202 displays the error in the index value when the geometrical imaging conditions are changed. Therefore, the X-ray diagnostic apparatus 1 according to the first embodiment makes it possible to perform various simulations related to the geometrical imaging conditions for the error in the index value.

[0069] (Variation 2) In the above-described embodiment, the scattered radiation dose is estimated based on scattered radiation data showing the relationship between the X-ray conditions, geometric imaging conditions, and body thickness, and the scattered radiation, and a "high-kV scattered radiation image" and a "low-kV scattered radiation image" are respectively acquired. However, the embodiment is not limited to this, and a "high-kV scattered radiation image" and a "low-kV scattered radiation image" may be respectively acquired using AI (artificial intelligence). In such a case, for example, a trained model is generated in advance using captured images and scattered radiation images based on the captured images as training data, and stored in memory 17. The calculation function 203 inputs the captured images (high-kV image and low-kV image) into the trained model to acquire a "high-kV scattered radiation image" and a "low-kV scattered radiation image." This allows the error of the index value to be displayed using only the captured images, without using the imaging conditions.

[0070] (Second embodiment) In the above-described first embodiment, a case where an error in an index value includes an error due to scattered radiation and an error due to quantum noise, etc. is described. In the second embodiment, a case where an error in an index value includes an error in the estimation accuracy of the scattered radiation amount and an error due to quantum noise, etc. is described. Note that the X-ray diagnostic apparatus 1 according to the second embodiment differs from the X-ray diagnostic apparatus 1 according to the first embodiment in the processing content by the calculation function 203. This will be mainly described below.

[0071] The processing procedure according to the second embodiment will be described below with reference to Fig. 7. Fig. 7 shows details of the processing in step S102 in Fig. 2. Here, BMD (bone mineral density) will be used as an example of an index for evaluating the bone condition of a subject.

[0072] For example, in the X-ray diagnostic apparatus 1 according to the second embodiment, as shown in FIG. 7, first, the calculation function 203 sets an ROI for the acquired X-ray image in the same manner as in the first embodiment (step S301).

[0073] Next, the calculation function 203 calculates the scattered radiation amount and the error in the estimation accuracy of the scattered radiation at each pixel for each of the two types of X-ray image data collected by dual energy imaging (step S302).

[0074] (Errors in the estimation accuracy of scattered radiation) The calculation function 203 calculates an error in the estimation accuracy of scattered radiation based on the imaging conditions. Specifically, the calculation function 203 calculates an "error in the estimation accuracy of scattered radiation" resulting from, for example, a discrepancy between the value used to estimate the scattered radiation dose and the actual value in information related to X-ray conditions and body thickness. For example, estimation accuracy data indicating the range of possible scattered radiation doses is generated in advance for each condition and stored in the memory 17. The calculation function 203 calculates the range of possible scattered radiation doses for each dual-energy imaging based on the estimation accuracy data. The calculation function 203 according to the second embodiment calculates an error in the measurement value based on the above-mentioned range of possible scattered radiation doses.

[0075] For example, the calculation function 203 estimates the error of the measurement value by statistical processing using the range of the amount of scattered radiation that can be estimated based on the imaging conditions of the "high kV image" and the range of the amount of scattered radiation that can be estimated based on the imaging conditions of the "low kV image." As an example, the calculation function 203 estimates the maximum range or the minimum range in the range based on the imaging conditions of the "high kV image" and the range based on the imaging conditions of the "low kV image" as the error of the measurement value.

[0076] Next, the calculation function 203 corrects the deviation in X-ray dose due to scattered radiation and calculates a bone-enhanced image and a soft-tissue-enhanced image (step S303). Specifically, the calculation function 203 generates difference images (high-kV difference image, low-kV difference image) by subtracting the corresponding scattered radiation images from the high-kV image and the low-kV image. Then, the bone-enhanced image and the soft-tissue-enhanced image are generated based on material decomposition processing using the difference images. Note that the corresponding scattered radiation images are generated from the high-kV image and the low-kV image using any of the methods described in the first embodiment.

[0077] Then, the calculation function 203 calculates the "error caused by quantum noise, etc." (step S304). Note that this step is executed using any of the methods described in the first embodiment, similar to step S204 in FIG.

[0078] Thereafter, the calculation function 203 calculates the errors of the bone-enhanced image and the soft-tissue-enhanced image based on the "error in the estimation accuracy of the scattered radiation amount" and the "error due to quantum noise, etc." (Step S305). Specifically, the calculation function 203 calculates the errors of the bone-enhanced image and the soft-tissue-enhanced image by a numerical method or an analytical method using the "error in the estimation accuracy of the scattered radiation amount" and the "error due to quantum noise, etc."

[0079] Then, the calculation function 203 calculates the measurement value and error of the bone density (step S306). Specifically, the calculation function 203 calculates the measurement value of the bone density based on the material decomposition process executed in step S303. The calculation function 203 also calculates the error of the measurement value of the bone density based on the error of the enhanced image calculated in step S305.

[0080] As described above, once the bone mineral density measurement value and error are calculated, the control function 202 displays the bone mineral density measurement value and error on the display 18 (step S307). Figure 8 is a diagram showing an example of information displayed on the display 18. The vertical axis indicates bone mineral density (BMD), and the horizontal axis indicates the examination date.

[0081] For example, the control function 202 displays the bone density measurement values ​​for "Date: a" and "Date: b", as well as an error bar indicating the error in the bone density measurement values ​​calculated based on "errors in the estimation accuracy of scattered radiation dose" and "errors due to quantum noise, etc."

[0082] As in the first embodiment, the control function 202 can display the error in the measurement value when the geometric imaging conditions are changed. That is, the calculation function 203 calculates the "error in the estimation accuracy of the scattered radiation dose" when conditions such as the position information of the aperture blades, SID, and SOD are changed. Then, the calculation function 203 calculates the error in the measurement value of bone density using the calculated "error in the estimation accuracy of the scattered radiation dose."

[0083] The control function 202 displays the error in the measurement value when the geometrical imaging conditions are changed. FIG. 9 is a diagram showing an example of information displayed on the display 18 when the geometrical imaging conditions are changed, and shows a case where the error in the measurement value when the geometrical imaging conditions are changed for "Date: b" in FIG. 8 is displayed. For example, the control function 202 displays the error in the measurement value when the geometrical imaging conditions are changed (the error bar shown by the dotted line) alongside the display of the measurement value and error for "Date: b." Note that in the second embodiment, as in the first embodiment, the display of the error in the measurement value when the geometrical imaging conditions are changed, which is simulated, can be displayed in various ways.

[0084] In the above-described embodiment, a case where bone density is used as an index value for evaluating the bone condition of a subject has been described, but the embodiment is not limited to this, and bone mineral content may also be used as an index value for evaluating the bone condition of a subject.

[0085] As described above, according to the second embodiment, the calculation function 203 estimates the error in the index value using the error in the estimation accuracy of the scattered radiation amount. Therefore, the X-ray diagnostic apparatus 1 according to the second embodiment can calculate the error corresponding to the estimation error of the scattered radiation amount.

[0086] (Third embodiment) In the third embodiment, a case will be described in which scattered rays are estimated using pixel values ​​in an area where X-rays are blocked by the aperture blades. That is, in the third embodiment, errors caused by scattered rays are calculated based on an image. FIG. 10 is a block diagram showing an example of the configuration of an X-ray diagnostic apparatus 1a according to the third embodiment. Note that the X-ray diagnostic apparatus 1a according to the third embodiment differs from the X-ray diagnostic apparatus 1 according to the first embodiment in that the processing circuitry 20a newly executes a correction function 204 and in the processing content of the calculation function 203. These will be mainly described below. Note that the correction function 204 is an example of a correction unit.

[0087] The correction function 204 corrects the amount of scattered radiation in the ROI based on pixel values ​​in the region other than the X-ray irradiation region defined by the X-ray aperture. Specifically, the correction function 204 first calculates the amount of scattered radiation in the region where X-rays are blocked, using the detection signal detected in the region where X-rays are blocked by the aperture blades as a signal caused by scattered radiation.

[0088] Then, the correction function 204 generates a coordinate-dependent scattered radiation function in the X-ray irradiation area (area where X-rays are not blocked by the aperture blades) based on the scattered radiation image estimated by the calculation function 203, and corrects the generated scattered radiation function using the amount of scattered radiation in the area where X-rays are blocked. For example, the correction function 204 multiplies the scattered radiation function by a constant at the boundary of X-ray irradiation by the aperture blades (the boundary between the position where X-rays are irradiated and the position where X-rays are blocked) so that the amount of scattered radiation based on the above-mentioned coordinate-dependent scattered radiation function becomes continuous.

[0089] Then, the correction function 204 calculates the amount of scattered radiation at each position in the X-ray irradiation area based on the corrected scattered radiation function. The calculation function 203 calculates the error of the measurement value using the amount of scattered radiation calculated by the correction function 204. Note that the scattered radiation image estimated by the calculation function 203 may be estimated based on the imaging conditions, or may be estimated using AI.

[0090] As described above, the X-ray diagnostic apparatus 1a according to the third embodiment can estimate the amount of scattered radiation using pixel values ​​in the region where X-rays are blocked by the aperture blades. Furthermore, the X-ray diagnostic apparatus 1a according to the third embodiment may estimate the amount of scattered radiation based on the position of the ROI.

[0091] Specifically, the calculation function 203 estimates the scattered radiation amount according to the aperture of the aperture blade or the distance from the ROI to the aperture blade. For example, if the aperture of the aperture blade or the distance from the ROI to the aperture blade is greater than a threshold, the calculation function 203 estimates the scattered radiation amount by the method described in the first embodiment. Here, the calculation function 203 may use the corrected scattered radiation amount calculated by the correction function 204 described above.

[0092] On the other hand, if the aperture blade opening or the distance from the ROI to the aperture blade is smaller than the threshold, the calculation function 203 calculates the amount of scattered radiation within the ROI based on pixel values ​​in an area other than the X-ray irradiation area defined by the X-ray aperture. That is, the calculation function 203 estimates the amount of scattered radiation within the ROI based on detection signals detected in an area where X-rays are blocked by the aperture blade. For example, the calculation function 203 calculates the amount of scattered radiation in the area where X-rays are blocked based on detection signals detected in the area, and uses the calculated amount of scattered radiation as the amount of scattered radiation within the ROI.

[0093] As described above, according to the third embodiment, the correction function 204 corrects the amount of scattered radiation within the ROI based on pixel values ​​in the region other than the X-ray irradiation region defined by the X-ray aperture. Therefore, the X-ray diagnostic apparatus 1a according to the third embodiment can correct the estimated amount of scattered radiation based on the amount of scattered radiation that is actually detected, making it possible to present a more accurate error.

[0094] According to the third embodiment, the calculation function 203 estimates the amount of scattered radiation in the ROI based on the position of the ROI. Therefore, the X-ray diagnostic apparatus 1a according to the third embodiment makes it possible to estimate the amount of scattered radiation according to the position of the ROI.

[0095] Furthermore, according to the third embodiment, the calculation function 203 calculates the amount of scattered radiation within the ROI based on pixel values ​​in an area other than the X-ray irradiation area defined by the X-ray aperture. Therefore, the X-ray diagnostic apparatus 1a according to the third embodiment makes it possible to estimate the amount of scattered radiation using the amount of scattered radiation that is actually detected.

[0096] (Other embodiments) Up to this point, the first to third embodiments have been described, but the present invention may be embodied in various different forms other than the first to third embodiments described above.

[0097] In the above-described embodiment, the case where the measurement value and error of the index value (bone density, bone mineral content, etc.) are displayed after dual energy imaging has been described. However, the embodiment is not limited to this, and it is also possible to calculate the error based on the imaging conditions before imaging, and determine whether the imaging conditions are appropriate and notify the result.

[0098] In such a case, the calculation function 203 calculates the error of the index value (bone density, bone mineral content, etc.) based on the imaging conditions used for a single DXA imaging (or imaging conditions used for imaging with a two-layer detector), and performs a judgment regarding the imaging conditions based on the calculated error and the past measurement value of the index value (bone density, bone mineral content, etc.) corresponding to the calculated error. The control function 202 displays the judgment result.

[0099] Here, the calculation function 203 can execute the above-mentioned determination by determining the imaging conditions by comparison with the absolute value and determining the conditions related to the evaluation of changes from past index values ​​(bone density, bone mineral content, etc.). These will be explained in order below.

[0100] First, when determining the imaging conditions by comparison with absolute values, the calculation function 203 calculates a representative error amount in the measurement value of the index value (bone density, bone mineral content, etc.) based on the geometric imaging conditions and X-ray conditions. For example, the calculation function 203 acquires information about the past body thickness of the subject to be examined, and calculates the error in the measurement value of the index value (bone density, bone mineral content, etc.) based on the acquired information about the past body thickness and the geometric imaging conditions and X-ray conditions for the current imaging. Note that the information about the subject's body thickness may be estimated based on positioning by fluoroscopy. Furthermore, the calculation of the representative error amount based on the imaging conditions may be performed based on data in which representative error amounts are associated with each imaging condition, which is stored in advance in the memory 17.

[0101] The calculation function 203 then determines whether or not adding the calculated representative error amount to the measurement value of a past index value (bone density, bone mineral content, etc.) can cause a problem in comparison with the absolute value. Here, the absolute value can be the YAM (Young Adult Mean) value, which indicates the degree of decrease when the bone density of a young adult is set to 100%, the average value for an age group corresponding to the age of the subject, the osteoporosis diagnostic threshold, etc. In other words, the calculation function 203 determines whether or not an error can cause a problem in the comparison when comparing such absolute values ​​with the measurement value.

[0102] The calculation function 203 can also recalculate the representative error amount in response to changes in the imaging conditions and determine whether the problem in the comparison with the absolute value is resolved. Note that the above-mentioned representative error amount may be set to a larger value in anticipation of the amount of change from the past in the index value (bone density, bone mineral content, etc.) measured this time.

[0103] Fig. 11 is a diagram for explaining an example of processing by the calculation function 203 and the control function 202 according to another embodiment. The vertical axis indicates bone mineral density (BMD), and the horizontal axis indicates the examination date. Fig. 11 also shows an example of a case where a determination regarding imaging conditions is performed before the examination on "Date: b."

[0104] For example, the calculation function 203 calculates a representative error amount based on the imaging conditions "Parameter A: 1111, Parameter B: 2222" used in the examination on "Date: b." Then, the calculation function 203 determines whether the threshold value "e" is included in the error range when the representative error amount is added to the BMD measurement value in the examination on "Date: a." In other words, the calculation function 203 determines whether the threshold value "e" is exceeded or not, depending on the error.

[0105] For example, as shown in the upper diagram of Fig. 11, when the threshold value "e" is included within the error range, the calculation function 203 determines that there is a problem in comparison with the threshold value. The control function 202 causes the display 18 to display, for example, the graph shown in the upper diagram of Fig. 11 as the determination result. Here, when it is determined that there is a problem in comparison with the threshold value, the control function 202 can further display information (for example, an alert) indicating that the shooting conditions are not appropriate in addition to displaying the graph shown in the upper diagram of Fig. 11.

[0106] Then, as shown in the lower diagram of FIG. 11 , the calculation function 203 recalculates the representative error amount in response to the process of changing the imaging conditions from "parameter A: 1111" to "parameter A: 3333." Furthermore, the calculation function 203 determines whether the threshold value "e" is included within the error range when the representative error amount is added to the BMD measurement value in the examination on "Date: a." Here, as shown in the lower diagram of FIG. 11 , if the threshold value "e" is not included within the error range, the calculation function 203 determines that the imaging conditions are appropriate. The control function 202 displays the graph shown in the lower diagram of FIG. 11 on the display 18 in response to the change in imaging conditions.

[0107] The imaging conditions may be changed based on an input operation by the operator, or may be changed automatically by the calculation function 203 based on preset information.

[0108] Next, when determining conditions for evaluating changes from past measurement values ​​of index values ​​(bone density, bone mineral content, etc.), the calculation function 203 determines a threshold value for an estimated error based on the past measurement values ​​of index values ​​(bone density, bone mineral content, etc.) and the purpose of the measurement. That is, the calculation function 203 determines a threshold value (such as threshold e in FIG. 11) for determining whether or not the imaging conditions are appropriate based on the past measurement values, the purpose, and the estimated error.

[0109] For example, the calculation function 203 sets a smaller threshold value as the measured value of the index value (bone density, bone mineral content, etc.) becomes smaller. In addition, the calculation function 203 sets a larger threshold value when the purpose of the measurement is a health checkup, sets a smaller threshold value when the purpose is to evaluate the efficacy of a drug, and sets a threshold value somewhere in between these two when the purpose is follow-up observation that does not include evaluation of the efficacy of a drug.

[0110] In addition, the above-mentioned determination of the shooting conditions by comparison with absolute values ​​and the determination of the conditions related to the evaluation of changes from past measurement values ​​of index values ​​(bone density, bone mineral content, etc.) may both be performed, or only one of them may be performed.

[0111] Furthermore, in the above-described embodiment, the case where the error in the index value (bone density, bone mineral content, etc.) includes an error due to scattered radiation and an error due to quantum noise, etc., and a case where the error in the estimation accuracy of the scattered radiation dose and an error due to quantum noise, etc., are described. However, the embodiment is not limited to this, and any of the error due to scattered radiation, the error due to quantum noise, etc., or the error in the estimation accuracy of the scattered radiation dose may be considered as the error in the index value (bone density, bone mineral content, etc.).

[0112] In the above-described embodiment, the various processes are executed by an X-ray diagnostic apparatus. However, the embodiment is not limited to this, and each of the above-described processes may be executed by a medical image processing apparatus.

[0113] Fig. 12 is a block diagram showing an example of the configuration of a medical information processing device 3 according to another embodiment. As shown in Fig. 12, the medical information processing device 3 is connected to an X-ray diagnostic apparatus 1 via a network 2. The medical information processing device 3 has a communication interface 31, a memory 32, an input interface 33, a display 34, and a processing circuit 35. The medical information processing device 3 is, for example, an information processing device such as a tablet terminal or a workstation.

[0114] The communication interface 31 is connected to the processing circuitry 35, and controls the transmission and communication of various data between the processing circuitry 35 and the X-ray diagnostic apparatus 1 and the like connected via a network. For example, the communication interface 31 is realized by a network card, a network adapter, a NIC (Network Interface Controller), or the like.

[0115] The memory 32 is connected to the processing circuitry 35 and stores various data. For example, the memory 32 is realized by a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory, a hard disk, an optical disk, or the like. In this embodiment, the memory 32 stores X-ray image data received from the X-ray diagnostic apparatus 1 (fluoroscopic images collected for positioning and X-ray images collected by dual-energy imaging), etc. The memory 32 also stores various information used in processing by the processing circuitry 35, processing results by the processing circuitry 35, etc.

[0116] The input interface 33 may be realized by a trackball for performing various settings, switch buttons, a mouse, a keyboard, a touchpad for performing input operations by touching the operation surface, a touch monitor in which the display screen and touchpad are integrated, a non-contact input circuit using an optical sensor, an audio input circuit, etc. The input interface 33 is connected to the processing circuit 35 and converts input operations received from the operator into electrical signals and outputs them to the processing circuit 35. Note that in this specification, the input interface 33 is not limited to those having physical operation components such as a mouse and a keyboard. For example, a processing circuit that receives electrical signals corresponding to input operations from an external input device provided separately from the device and outputs these electrical signals to a control circuit is also included as an example of an input interface.

[0117] The display 34 is connected to the processing circuit 35 and displays various information and images output from the processing circuit 35. For example, the display 34 is realized by a liquid crystal monitor, a CRT (Cathode Ray Tube) monitor, a touch monitor, etc. For example, the display 34 displays a UI (User Interface) for receiving instructions from an operator, various images, and various processing results by the processing circuit 35.

[0118] The processing circuitry 35 controls each component of the medical information processing device 3 in response to an input operation received from an operator via the input interface 33. As shown in FIG. 12 , the processing circuitry 35 executes, for example, a control function 351, a calculation function 352, and a correction function 353. Here, for example, the processing functions executed by the control function 351, the calculation function 352, and the correction function 353, which are components of the processing circuitry 35 shown in FIG. 12, are recorded in the memory 32 in the form of a computer-executable program. The processing circuitry 35 is, for example, a processor, which reads each program from the memory 32 and executes it to realize a function corresponding to each read program. In other words, the processing circuitry 35 in a state in which each program has been read has each function shown in the processing circuitry 35 in FIG. 12.

[0119] The control function 351 controls the entire medical information processing device 3. The control function 351 also transmits and receives data to and from the X-ray diagnostic apparatus 1 and executes the same processing as the control function 202 described above. The calculation function 352 executes the same processing as the calculation function 203 described above. The correction function 353 executes the same processing as the correction function 204 described above.

[0120] In the X-ray diagnostic apparatus described in each embodiment, each processing function is stored in the memory 17 in the form of a program executable by a computer. The processing circuitry 20 is a processor that reads and executes the programs from the memory 17 to realize the function corresponding to each program. In other words, the processing circuitry 20, after reading each program, has the function corresponding to the read program. Note that, in each of the above-described embodiments, the case where each processing function is realized by a single processing circuitry 20 has been described, but the embodiment is not limited to this. For example, the processing circuitry 20 may be configured by combining multiple independent processors, and each processor may execute a program to realize each processing function. Furthermore, each processing function possessed by the processing circuitry 20 may be realized by being distributed or integrated as appropriate across a single or multiple processing circuits.

[0121] The term "processor" used in the above description refers to circuits such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an Application Specific Integrated Circuit (ASIC), a programmable logic device (e.g., a Simple Programmable Logic Device (SPLD), a Complex Programmable Logic Device (CPLD), and a Field Programmable Gate Array (FPGA)). The processor realizes its functions by reading and executing programs stored in storage 111.

[0122] In the above-described embodiments, the memory 17 is described as storing a program corresponding to each processing function. However, a configuration may be adopted in which multiple memories 17 are distributed and the processing circuit 20 reads out the corresponding program from each memory 17. Also, instead of storing the program in the memory 17, the program may be directly embedded in the circuit of the processor. In this case, the processor realizes the function by reading and executing the program embedded in the circuit.

[0123] The components of each device according to the above-described embodiments are conceptual and functionally independent, and are not necessarily physically configured as shown in the drawings. In other words, the specific form of distribution and integration of each device is not limited to that shown in the drawings, and all or part of the devices can be functionally or physically distributed and integrated in any unit depending on various loads, usage conditions, etc. Furthermore, all or any part of the processing functions performed by each device can be realized by a CPU and a program analyzed and executed by the CPU, or can be realized as hardware using wired logic.

[0124] The control method described in the above-described embodiment can be realized by executing a prepared control program on a computer such as a personal computer or a workstation. This control program can be distributed via a network such as the Internet. This control program can also be recorded on a non-transitory computer-readable recording medium such as a hard disk, flexible disk (FD), CD-ROM, MO, or DVD, and executed by being read from the recording medium by a computer.

[0125] According to at least one of the embodiments described above, it is possible to appropriately evaluate time-series changes in the condition of the bones of a subject.

[0126] Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0127] 1, 1a X-ray diagnostic equipment 3 Medical information processing equipment 20, 20a, 35 Processing circuit 202, 351 Control functions 203, 352 Calculation function 204, 353 correction function

Claims

1. a calculation unit that calculates an index value for evaluating a bone condition of a subject based on photographed images of the subject corresponding to X-rays of two different energies, and calculates an error in the index value based on at least one of the photographed images and photographing conditions when the photographed images are taken; a display control unit that displays an error in the calculated index value as an error bar on a graph showing the numerical values ​​of the index value at a plurality of time points at which the index value was measured; An X-ray diagnostic apparatus comprising:

2. The X-ray diagnostic apparatus according to claim 1 , wherein the calculation unit calculates an error in an index value for evaluating a bone condition of the subject based on a geometric imaging condition in the imaging conditions.

3. 3. The X-ray diagnostic apparatus according to claim 1, wherein the calculation unit calculates statistical information of the index values ​​measured in each of a plurality of regions set in the captured image as an error in the index value for evaluating the bone condition of the subject.

4. The X-ray diagnostic apparatus according to claim 2 , wherein the calculation unit estimates an amount of scattered radiation incident within a region of interest based on the geometrical imaging conditions, and calculates an error in the index value based on the estimated amount of scattered radiation.

5. 5. The X-ray diagnostic apparatus according to claim 2, wherein the calculation unit estimates the error including an error due to quantum noise.

6. The X-ray diagnostic apparatus according to claim 2 , wherein the calculation unit estimates an amount of scattered radiation in the region of interest based on a position of the region of interest, and calculates an error in the index value based on the estimated amount of scattered radiation.

7. the calculation unit calculates an error in the index value when a geometrical imaging condition in the imaging condition is changed, 7. The X-ray diagnostic apparatus according to claim 2, wherein the display control unit displays an error in the index value when the geometrical imaging condition is changed.

8. a correction unit that corrects the amount of scattered radiation within the region of interest based on pixel values ​​in a region other than the X-ray irradiation region defined by the X-ray aperture; 7. The X-ray diagnostic apparatus according to claim 4, wherein the calculation unit calculates an error in the index value based on the amount of scattered radiation after correction.

9. The X-ray diagnostic apparatus according to claim 1 , wherein the calculation unit calculates the amount of scattered radiation within the region of interest based on pixel values ​​in a region other than the X-ray irradiation region defined by the X-ray aperture.

10. the calculation unit calculates an error in the index value based on a shooting condition of the captured image, and performs a determination regarding the conditions used for shooting the captured image based on the calculated error and a past measurement value corresponding to the error; 10. The X-ray diagnostic apparatus according to claim 1, wherein the display control unit displays the determination result.

11. a calculation unit that calculates an index value for evaluating a bone condition of a subject based on photographed images of the subject corresponding to X-rays of two different energies, and calculates an error in the index value based on at least one of the photographed images and photographing conditions when the photographed images are taken; a display control unit that displays an error in the calculated index value as an error bar on a graph showing the numerical values ​​of the index value at a plurality of time points at which the index value was measured; A medical information processing device comprising:

12. Calculating an index value for evaluating the bone condition of a subject based on photographed images of the subject corresponding to X-rays of two different energies, and calculating an error in the index value based on at least one of the photographed images and the photographing conditions when the photographed images are taken; a graph showing the index values ​​at the multiple time points at which the index values ​​were measured, the error of the calculated index values ​​being displayed as error bars of the numerical values; A program that causes a computer to perform each process.

Images