Radiographic system, radiographic method, information processing device, information processing method, program, radiographic device, imaging control device, and imaging control method

Abstract

A radiographic system that acquires bone information on the basis of a first radiographic image and a second radiographic image acquired by prescribed radiographic imaging, said radiographic system comprising a processing unit that causes a notification unit to issue an alert relating to the bone information on the basis of the irradiation time of the prescribed radiographic imaging.

Description

Radiography system, radiation imaging method, information processing device, information processing method, program, radiation imaging apparatus, imaging control device, and imaging control method

[0001] This disclosure relates to a radiography system, a radiography method, an information processing device, an information processing method, a program, a radiography apparatus, a radiography control device, and a radiography control method.

[0002] For the diagnosis of osteoporosis and other conditions, a measurement method called BMD (Bone Mineral Density) is used. As a method for measuring bone mineral density, for example, dual-energy X-ray absorptiometry (DEXA), also known as the "DEXA method," is a technique that uses two types of radiation (X-rays) with different energy distributions to measure bone density from the difference in X-ray absorption coefficients between soft tissue and bone tissue. Conventionally, bone density calculation devices using the DEXA method used line sensors to irradiate X-rays line by line and acquire data. Such devices have a fixed positional relationship between the X-ray irradiation position and the position of the X-ray receiving sensor, making them dedicated devices for DEXA.

[0003] In contrast, in recent years, digital image diagnosis using radiographic images acquired with flat panel sensors (hereinafter referred to as "FPDe"), which are radiation detection devices for general radiography different from those used for bone density measurement, has become widespread and is also being applied to bone density measurement. When performing bone density imaging using FPDe, X-rays are irradiated onto the entire surface of the FPD (cone beam imaging) to acquire a radiographic image, and calibration is required between the value calculated from the output value of the FPDe and the actual bone density value. By imaging a bone density calibration phantom (Quality Control phantom: hereinafter referred to as "QC phantom") with a known bone density, data for bone density calibration and bone density calibration values ​​can be obtained. By calibrating the value calculated from the output value of the FPDe with this bone density calibration value, the bone density can be determined.

[0004] Furthermore, the accuracy of bone density calculations may decrease depending on the state of two radiation images with different energy distributions. Patent Document 1 discloses a technique for evaluating whether the calculation accuracy has decreased due to the influence of gases within the subject.

[0005] Patent No. 6851259 specification

[0006] However, the technology described in Patent Document 1 has the problem that it is not possible to determine whether the accuracy of bone density calculation is reduced due to insufficient radiation exposure from the radiation generating device. In particular, with the DEXA method, it is not possible to determine whether or not there is insufficient radiation exposure by visual inspection of the image, which may result in inaccurate bone density calculations.

[0007] In view of the above issues, this disclosure provides a technology that can notify of insufficient radiation exposure in DEXA radiography.

[0008] A radiography system according to one aspect of the present disclosure is a radiography system that acquires bone information based on a first radiography image and a second radiographic image acquired by a predetermined radiography, and has processing means for causing a notification unit to notify a warning regarding bone information based on the radiation irradiation time of the predetermined radiography.

[0009] A radiography system according to another aspect of the present disclosure has a control means capable of performing a first radiography, in which one imaging is performed based on a single irradiation permission, and a second radiography, in which two imagings are performed based on a single irradiation permission, wherein the control means acquires bone information based on the two imagings obtained from the second radiography.

[0010] An information processing device according to another aspect of the present disclosure is an information processing device for processing information acquired from a radiography device capable of performing a first imaging for bone information calculation and a second imaging different from the first imaging for bone information calculation, the device having a processing means for determining whether the radiation exposure is insufficient based on a comparison of the radiation exposure time to the radiography device with the permitted time of the permitted radiation exposure standard, the processing means causing a warning display to be shown in the notification unit if the radiation exposure is insufficient based on the comparison.

[0011] An information processing method according to another aspect of the present disclosure is an information processing method for an information processing device that processes information acquired from a radiography apparatus capable of performing a first imaging for bone information calculation and a second imaging different from the first imaging for bone information calculation, comprising: a determination step of determining whether radiation irradiation is insufficient based on a comparison of the radiation irradiation time to the radiography apparatus with the permitted time of the permitted standard for radiation irradiation; and a notification step of causing a warning display to be shown in a notification unit if the radiation irradiation is insufficient based on the comparison.

[0012] According to this disclosure, it will be possible to notify of insufficient radiation exposure in DEXA radiography. This will enable the acquisition of bone information of the subject with high accuracy.

[0013] The attached drawings are included in the specification and constitute a part thereof, illustrating embodiments in this disclosure and used to explain the technical ideas derived from this disclosure together with their descriptions. A diagram showing the configuration of a radiography apparatus according to the first embodiment. A diagram showing the configuration of an amplification unit according to the first embodiment. A diagram showing a processing flow including radiation insufficiency determination according to the first embodiment. A diagram showing an example sequence for radiation insufficiency determination in DEXA imaging according to the first embodiment. A diagram showing an example sequence for radiation insufficiency determination in DEXA imaging according to the first embodiment. A diagram showing an example configuration of a radiography system according to the first embodiment. A diagram showing an example of DEXA imaging operation in a radiography apparatus according to the first embodiment. A diagram explaining the principle for calculating bone density using the DEXA method according to the first embodiment. A diagram showing an example of notification in case of insufficient irradiation according to the first embodiment. A diagram showing an example of notification in case of insufficient irradiation according to the first embodiment. A diagram showing an example sequence in general radiography different from DEXA imaging according to the first embodiment. A diagram showing an example configuration of a radiography system of an embodiment. A diagram explaining the relationship between switching the imaging mode and the first waiting time and the second waiting time in a radiography system of the second embodiment. A diagram illustrating the process of switching from the first to the second imaging mode as one of several imaging modes with different radiation doses in the second embodiment of the radiography system. A diagram illustrating the first and second waiting times in the third embodiment of the radiography system. A diagram illustrating the process when an instruction to switch to the third imaging mode is received during the waiting period after switching from the first to the second imaging mode in the fourth embodiment of the radiography system. A diagram illustrating the process when an instruction to switch to the third imaging mode is received during the waiting period after switching from the first to the second imaging mode in the fourth embodiment of the radiography system. A diagram schematically showing the relationship between the switching of imaging modes and the first and second waiting times in the third embodiment of the radiography system. A diagram showing an example configuration of a bone density measurement system in the fifth embodiment. A diagram showing the relationship between the difference in transmittance between bone and soft tissue and the bone density value for low-energy and high-energy radiation. A diagram showing an example configuration of a radiography device in the fifth embodiment. A diagram showing a detailed circuit configuration example of the amplification unit.A diagram showing the imaging flow for DEXA imaging in the bone density measurement system of the fifth embodiment. A diagram illustrating the alignment process for aligning the QC phantom during QC imaging with the position of the bone to be measured in the subject during DEXA imaging in the fifth embodiment. A diagram showing the imaging flow for follow-up observation of DEXA imaging in the bone density measurement system of the fifth embodiment. A diagram illustrating the process for aligning the position and posture of the subject for follow-up observation.

[0014] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the scope of the claims. While the embodiments describe multiple features, not all of these features are necessary, and the features may be combined in any way. Furthermore, in the attached drawings, the same or similar configurations are given the same reference numeral, and redundant descriptions are omitted. The radiation in the disclosed art includes not only beams of alpha rays, beta rays, gamma rays, etc., which are produced by particles (including photons) emitted by radioactive decay, but also beams with energy of equal or greater energy, such as X-rays, particle beams, and cosmic rays.

[0015] (First Embodiment) Figure 5 shows an example configuration of a radiography system 500 including a radiography apparatus 100, according to the first embodiment of radiography. The radiography apparatus 100 is capable of performing a first radiography, which involves taking one image based on a single irradiation permission, and a second radiography, which involves taking two images based on a single irradiation permission. The radiography system 500 includes the radiography apparatus 100, an information processing device 502, an access point 503, a communication device 504, a synchronization control device 505, a radiation generator 506, and a bone information calculation device 510. The radiography apparatus 100 is capable of performing a first radiography for bone information calculation and a second radiography (general radiography) that is different from the first radiography for bone information calculation.

[0016] The radiography device 100 captures a radiographic image based on the radiation 507 that has passed through the subject H. The radiation incident on the radiography device 100 is converted into an electric charge, which is then processed as image data and sent to the information processing device 502.

[0017] The information processing device 502 is a control device implemented using known technologies such as a general-purpose computer, and includes a display unit, an input unit, a storage unit, and a control unit. The information processing device 502 performs image processing for correction, storage, and display of image data received from the radiography apparatus 100. At this time, some or all of the image processing functions may be performed by the radiography apparatus 100. Functionally, the information processing device 502 includes a determination unit that determines whether radiation exposure is insufficient based on a comparison of the radiation exposure time to the radiography apparatus 100 with the permitted radiation exposure time standard, and a notification unit that displays a warning on the display unit if radiation exposure is insufficient based on the comparison of radiation exposure times.

[0018] Furthermore, the information processing device 502 displays radiation images to the operator through the display unit and provides instructions for shooting. The information processing device 502 also has an input unit that allows the operator to input setting information such as shooting conditions and the light field 800, which is the area where radiation is detected. For example, before shooting, the above-mentioned shooting conditions, the light field 800, the maximum permitted irradiation time, and other input setting information are transmitted to the radiation imaging device 100 and set. The control unit of the information processing device 502 also has functions to compare the acquired signal strength with a threshold, respond to connection requests, and transmit information for communication via the wireless communication unit, such as wireless information, which will be described later.

[0019] The access point 503 is a device that relays radio waves for wireless information exchange between the radiography apparatus 100 and the information processing apparatus 502. At this time, the radiography apparatus 100's control unit 180 controls the communication unit 190 to perform wireless communication. In Figure 5, the access point 503 is connected to the information processing apparatus 502 via the synchronization control device 505, but it may also be directly connected to the information processing apparatus 502.

[0020] The communication device 504 is connected to the information processing device 502 and is a device that transmits and receives radio waves for performing short-range wireless communication between the radiation imaging device 100 and the information processing device 502. For example, the communication device 504 is a dongle connected to the information processing device 502 via a USB (Universal Serial Bus) interface. Further, the communication device 504 is a device corresponding to at least one of the Bluetooth (registered trademark) Basic Rate / Enhanced Data Rate (BR / EDR) standard or the Bluetooth Low Energy (BLE) standard.

[0021] Also, the communication device 504 may be an RFID (radio frequency identifier) device that exchanges information by short-range wireless communication using an electromagnetic field, radio waves, etc. from a tag embedded with ID information. The communication method of the RFID may be either an electromagnetic induction method or a radio wave method. Further, the communication device 504 may have an access point function.

[0022] In the above description and FIG. 5, an example where the communication device 504 is connected to the information processing device 502 is shown, but this is not the only case. The communication device 504 may be connected to other devices constituting the radiation imaging system 500, such as the radiation generation device 506. Also, the communication device 504 may be substituted by using a device pre-embedded in the radiation imaging system 500.

[0023] A status notification device 509 is connected to the information processing device 502 as a notification unit to the operator. The status notification device 509 notifies the operator of the current state of the radiation imaging device 100 or the completion of a specific process based on the information of the radiation imaging device 100 received from the radiation imaging device 100 via the access point 503 or received from the communication device 504.

[0024] The status notification device 509 uses a light emitter such as an LED, for example, and notifies the operator by associating a plurality of lighting patterns with the current state of the radiation imaging apparatus 100 in advance. Further, the status notification device 509 may use a sound source such as a speaker. In that case, the pattern of the buzzer sound is associated with the current state of the radiation imaging apparatus 100 in advance to notify the operator. These forms may also be used in combination.

[0025] Also, although an example in which the status notification device 509 is connected to the information processing device 502 has been shown, it may be substituted by using devices such as a display or a speaker provided in the information processing device 502.

[0026] The synchronization control device 505 (synchronization control unit) has a circuit that mediates communication and monitors the states of the radiation imaging apparatus 100 and the radiation generation device 506. For example, the synchronization control device 505 controls the irradiation of the radiation 507 from the radiation generation device 506 or controls the imaging of the subject H by the radiation imaging apparatus 100. Further, the synchronization control device 505 may incorporate a HUB or the like that connects a plurality of network devices.

[0027] The radiation generation device 506 has, for example, a radiation tube that accelerates electrons at a high voltage and collides them with an anode in order to generate radiation 507 such as X-rays. Note that typically X-rays are used as the radiation 507, but α-rays, β-rays, γ-rays, or neutron rays may also be used.

[0028] The in-hospital LAN 508 is a local area network constructed within the hospital and has a function of transmitting and receiving radiation images taken by the radiation imaging system 500 to and from various locations within the hospital.

[0029] In the radiation imaging system 500 shown in FIG. 5, the radiation 507 irradiated from the radiation generation device 506 is irradiated onto the subject H who is a patient. The radiation imaging apparatus 100 generates a radiation image based on the radiation 107 that has passed through the subject H.

[0030] The radiography system 500 can perform imaging using both synchronous and asynchronous imaging. Synchronized imaging is an imaging method in which the timing of radiation irradiation and imaging is synchronized by exchanging electrical synchronization signals between the radiography device 100 and the radiation generator 506 via a synchronization control device 505.

[0031] On the other hand, asynchronous imaging is an imaging method in which the radiography apparatus 100 starts imaging when it detects the incidence of radiation, without exchanging electrical synchronization signals between the radiography apparatus 100 and the radiation generator 506. In asynchronous imaging, the radiography apparatus 100 may transfer the radiation image after each imaging, or it may store the captured images internally in the radiography apparatus 100 without transferring them after each imaging.

[0032] Furthermore, the radiography system 500 can perform imaging under conditions commonly used in radiography, such as fluoroscopy, continuous imaging, still image imaging, DSA imaging, roadmap imaging, programmed imaging, tomography, tomosynthesis imaging, imaging for bone information calculation using the DEXA method, and bone suppression imaging to reduce bone density in radiographic images. In particular, this technology has the potential to improve the reliability of bone density calculation accuracy when imaging using the DEXA method, as even slight under-irradiation that is not visible to the naked eye can significantly affect the accuracy of bone density calculation. In bone suppression, when processing images using multiple images, there is the advantage that the user can choose whether or not to perform bone suppression processing when there is under-irradiation.

[0033] The radiography system 500 is configured with various functions, including the imaging frame rate, tube voltage, tube current, sensor readout area, sensor drive binning setting, collimator aperture setting, radiation window width, and whether or not to store radiation images in the radiography device 100.

[0034] The information processing device 502 receives input such as dose, upper limit irradiation time (ms), tube current (mA), tube voltage (kV), and the region of interest (ROI) where radiation should be monitored, through an input device provided in the information processing device. When the exposure switch attached to the radiation generator 506 is operated (irradiation start operation), the synchronization control device 505 transmits a start request signal (irradiation permission request signal) to the radiography device 100. The start request signal is a signal requesting the start of radiation irradiation.

[0035] Upon receiving a start request signal (irradiation permission request signal), the radiography apparatus 100 begins preparing to accept radiation irradiation. Once the radiography apparatus 100 is ready for imaging, it transmits a start-ready signal (irradiation permission signal) to the radiation generator 506 via the access point 503 or communication device 504. The start-ready signal is a signal that indicates that it is possible to start radiation irradiation. Upon receiving the start-ready signal (irradiation permission signal), the radiation generator 506 begins irradiating with radiation 507. After radiation irradiation stops, the radiography apparatus 100 sequentially scans the drive lines 110 (drive lines 110 other than the detection drive line 111) to which only the imaging pixels 101 are connected, and acquires a radiation image by reading the image signal of each imaging pixel 101 with the readout circuit 160. In the first imaging for bone information calculation, the radiography apparatus 100 functions as an acquisition unit that acquires a first radiographic image generated by irradiation with radiation of a first energy, and a second radiographic image generated by irradiation with radiation of a second energy different from the first energy.

[0036] The radiation generator 506 and the information processing device 502 are connected by a serial communication cable, and the irradiation conditions are set and radiation implementation information (results such as the mAs value after radiation irradiation) is obtained from the information processing device 502. Alternatively, the connection may be made using Ethernet instead of a serial communication cable.

[0037] Furthermore, the synchronization control device 505 and the radiation generator 506 are connected by a dedicated line and communicate whether or not there is a request for irradiation permission, whether radiation irradiation is permitted, and whether irradiation is stopped. The synchronization control device 505 receives an irradiation request (start request signal) from the radiation generator 506. The synchronization control device 505 also sends an irradiation permission (start ready signal) synchronized with the imaging timing of the radiography device 100 to the radiation generator 506, causing the radiation generator 506 to irradiate with radiation.

[0038] Furthermore, the radiation generator 506 stops irradiating with radiation when the exposure switch is released or when the maximum permitted irradiation time, which has been set in advance, is reached.

[0039] The radiography apparatus 100 transmits the image generated by receiving radiation to the information processing device 502, and the information processing device 502 displays the radiation image acquired from the radiography apparatus 100 on a display unit. After imaging, the information processing device 502 also transmits the radiation image to the bone information calculation device 510 via the hospital LAN 508, and the bone information calculation device 510 calculates the bone information of the subject. In the DEXA method, the bone information calculation device 510 acquires two radiation images with different energy distributions (a first radiation image and a second radiation image) and functions as a calculation unit that calculates the bone information of the subject using the two radiation images. Here, the bone information of the subject includes at least one of bone mineral density and bone density.

[0040] Figure 1 shows an example configuration of a radiography apparatus 100 according to the first embodiment. The radiography apparatus 100 has a plurality of pixels arranged in an imaging area IR to form a plurality of rows and a plurality of columns, a plurality of drive lines 110, and a plurality of signal lines 120. The plurality of drive lines 110 are arranged corresponding to a plurality of rows of pixels, with each drive line 110 corresponding to any one pixel row. The plurality of signal lines 120 are arranged corresponding to a plurality of columns of pixels, with each signal line 120 corresponding to any one pixel column.

[0041] The multiple pixels include multiple imaging pixels 101 used to acquire a radiation image. Each imaging pixel 101 includes a conversion element 102 that converts radiation into an electrical signal, and a switch element 103 that connects the corresponding signal line 120 to the conversion element 102.

[0042] The conversion element 102 may consist of a scintillator that converts radiation into light and a photoelectric conversion element that converts light into an electrical signal. The scintillator is generally formed in a sheet shape to cover the imaging area IR and is shared by multiple pixels. Alternatively, the conversion element 102 may consist of a conversion element that directly converts radiation into an electrical signal.

[0043] The switching element 103 may include, for example, a thin-film transistor (TFT) in which the active region is made of a semiconductor such as amorphous silicon or polycrystalline silicon.

[0044] The first electrode of the conversion element 102 is connected to the first main electrode of the switch element 103, and the second electrode of the conversion element 102 is connected to the bias line 130. One bias line 130 extends in the column direction and is commonly connected to the second electrodes of multiple conversion elements 102 arranged in the column direction. The bias line 130 receives a bias voltage Vs from the power supply circuit 140. The second main electrode of the switch element 103 of one or more imaging pixels 101 included in one column is connected to one signal line 120. The control electrode of the switch element 103 of one or more imaging pixels 101 included in one row is connected to one drive line 110.

[0045] The drive circuit 150 is configured to supply drive signals to the pixels to be driven through a plurality of drive lines 110 according to signals from the control unit 180. In the first embodiment, the drive signal is a signal to turn on the switch element included in the pixel to be driven. The switch element of each pixel is turned on by a high-level signal and turned off by a low-level signal. Therefore, this high-level signal is called the drive signal. When a drive signal is supplied to a pixel, the signal stored in the conversion element of that pixel becomes readable by the read circuit 160.

[0046] The readout circuit 160 is configured to read signals from multiple pixels through multiple signal lines 120. The readout circuit 160 includes multiple amplification units 161, a multiplexer 162, and an analog-to-digital converter (hereinafter referred to as an A / D converter (ADC)) 163.

[0047] Each of the multiple signal lines 120 is connected to the corresponding amplifier unit 161 among the multiple amplifier units 161 of the readout circuit 160. One signal line 120 corresponds to one amplifier unit 161. The multiplexer 162 selects the multiple amplifier units 161 in a predetermined order and supplies the signals from the selected amplifier units 161 to the AD converter 163. The AD converter 163 converts the supplied signals into digital signals and outputs them.

[0048] The signal read from the imaging pixel 101 is supplied to the signal processing unit 170, where it is processed through calculations, storage, and other operations. Specifically, the signal processing unit 170 includes a calculation unit 171 and a storage unit 172. The calculation unit 171 generates a radiation image based on the signal read from the imaging pixel 101 and supplies it to the control unit 180.

[0049] The control unit 180 controls the drive circuit 150 and the read circuit 160 based on information from the signal processing unit 170. Based on information from the signal processing unit 170, the control unit 180 controls, for example, the start and end of exposure (accumulation of charge corresponding to radiation irradiated by the imaging pixel 101). The control unit 180 may be composed of a general-purpose processing circuit such as a microprocessor, or it may be composed of a dedicated processing circuit such as an ASIC (Application Specific Integrated Circuit). If the control unit 180 is composed of a general-purpose processing circuit, the control unit 180 may further include a memory.

[0050] In the DEXA method, in order to acquire two radiation images with different energy distributions, the control unit 180 controls the drive circuit 150 for multiple frames, thereby enabling the acquisition of radiation images with different energy distributions. Furthermore, during acquisition, the control unit 180 can determine radiation deficiency from the status of the exposure permission request signal from the synchronization control device 505 and radiation irradiation information from the radiation generator 506 (information related to mAs values ​​and irradiation stoppage).

[0051] The communication unit 190 is controlled by the control unit 180 and has the function of communicating between the radiography apparatus 100 and external devices (for example, an information processing device 502, a synchronization control device 505, a radiation generator 506, a bone information calculation device 510, etc.). Communication can be performed using any communication unit 190 that implements the desired method and standard of communication, such as wired communication or wireless communication, and is not limited to a specific standard. Furthermore, multiple communication units 190 may be installed to support multiple communication standards.

[0052] Figure 2 shows a detailed circuit configuration example of the amplification unit 161. The amplification unit 161 includes a differential amplifier circuit AMP and a sample-and-hold circuit SH. The differential amplifier circuit AMP amplifies the signal appearing on the signal line 120 and outputs it. The control unit 180 can reset the potential of the signal line 120 by supplying a signal φR to the switching element of the differential amplifier circuit AMP.

[0053] The output from the differential amplifier circuit AMP can be held by the sample-and-hold circuit SH. The control unit 180 causes the sample-and-hold circuit SH to hold the signal by supplying a signal φSH to the switch element of the sample-and-hold circuit SH. The signal held by the sample-and-hold circuit SH is read out by the multiplexer 162.

[0054] Figure 3 illustrates a processing flow including radiation exposure deficiency determination according to the first embodiment. Referring to Figure 3, a method by which the control unit 180 or information processing device 502 of the radiation imaging apparatus 100 determines radiation exposure deficiency will be described.

[0055] In step S301, the radiography apparatus 100 first turns on the power to the control unit 180 and enters a state where it can communicate with the radiation generator 506 and the information processing device 502.

[0056] In step S302, when the information processing device 502 performs imaging by the DEXA method (BMD imaging) based on user operation, it transmits setting information necessary for BMD imaging (imaging conditions including imaging parameters such as the time to accumulate charge and the number of images to be acquired) to the radiography apparatus 100. The radiography apparatus 100 transmits the setting information (imaging conditions including imaging parameters) received from the information processing device 502 to the synchronization control device 505. Note that the transmission of setting information to the synchronization control device 505 may also be transmitted from the radiation generator 506 or the information processing device 502.

[0057] When the control unit 180 receives an instruction from the synchronization control device 505 to start preparing for image capture, it resets the charge of the conversion element 102 as a preparatory operation and prepares for image generation. In terms of power consumption, it is preferable for the control unit 180 to periodically reset the charge of the conversion element 102.

[0058] In step S303, the control unit 180, based on the reception of an irradiation permission request signal from the radiation generator 506 via the synchronization control device 505, prepares for imaging and then starts imaging. When the control unit 180 receives an irradiation permission request signal from the radiation generator 506 via the synchronization control device 505 (S402, S403 in Figure 4A), it resets the charge of the conversion element 102 and controls the readout circuit and drive circuit so that the conversion element 102 can accumulate and read out charge due to radiation. The control unit 180 determines the start of radiation irradiation from the communication status between the synchronization control device 505 and the radiography device 100. Specifically, this is the reception of a start request signal (irradiation permission request signal) from the synchronization control device 505 (S403 in Figure 4A) or the transmission of a start-ready signal (irradiation permission signal) from the radiography device 100 (S405 in Figure 4A). By determining that communication of irradiation information including one of these has taken place, it is possible to determine whether or not irradiation has started in that imaging. If there is no irradiation information (S303-NO), the process returns to S302 because radiation has not yet been emitted from the radiation generator 506. On the other hand, if the determination in S303 indicates that there is irradiation information (S303-YES), the control unit 180 determines that radiation irradiation has started and proceeds to S304.

[0059] In step S304, the control unit 180 determines, via the synchronization control device 505, whether the irradiation permission request signal has been invalidated in the radiation generator 506 (for example, S411 in Figure 4B). Specifically, if the irradiation permission request signal is invalidated before the permitted time for radiation irradiation has elapsed to the maximum permitted irradiation time (standard permitted time), the synchronization control device 505 determines that irradiation has stopped and sends an irradiation stop signal to the radiography device 100 (for example, S412 in Figure 4B). When the control unit 180 receives the irradiation stop signal from the synchronization control device 505, it determines that radiation irradiation has stopped (S304-YES) and proceeds to S305. On the other hand, in the determination in S304, if the control unit 180 does not receive an irradiation stop signal from the synchronization control device 505 before the preset standard permitted time (maximum permitted irradiation time), it determines that radiation irradiation has not stopped (S304-NO) and proceeds to S307.

[0060] In step S305, the control unit 180 or the information processing device 502 determines whether there was insufficient radiation (insufficient irradiation) in the imaging. The determination of whether there was insufficient radiation in the imaging is made during the period from the receipt of the aforementioned start request signal (radiation permission request signal) to the end of imaging to the information processing device 502 (for example, the end of image transmission or the end of charge reading). The control unit 180 or the information processing device 502 can determine whether there was insufficient radiation based on a comparison of the radiation irradiation time to the radiography device with a preset standard permission time (maximum irradiation permission time). If the radiation irradiation time ends before the preset standard permission time (maximum irradiation permission time), the control unit 180 determines that there was insufficient radiation (insufficient irradiation dose) (S305-YES), and proceeds to S306. On the other hand, if the determination in S305 indicates that the radiation irradiation time has reached the predetermined standard permitted time (maximum permitted irradiation time) and has ended, the control unit 180 determines that there is no shortage of radiation irradiation (S305-NO) and proceeds to S307.

[0061] Furthermore, as a method for determining insufficient radiation exposure, the control unit 180 or the information processing device 502 can determine insufficient radiation (insufficient radiation dose) by comparing the radiation exposure information received from the radiation generator 506 with pre-set setting information (such as mAs value). In other words, the control unit 180 or the information processing device 502 may determine whether the radiation exposure to the radiography device is insufficient based on a comparison of the radiation exposure information emitted from the radiation generator 506 with pre-acquired standard radiation exposure information. Here, the radiation exposure information includes at least one of the following: the tube voltage when irradiating with radiation, the radiation exposure time, the tube current when irradiating with radiation, and the integrated value (mAs) of the tube current and the radiation exposure time.

[0062] In step S306, the control unit 180 notifies at least one of the information processing device 502 or the bone information calculation device 510 of the occurrence of insufficient radiation exposure. At least one of the information processing device 502 or the bone information calculation device 510 performs display control to display a warning to the user that there may be insufficient radiation exposure or low bone density calculation accuracy.

[0063] In step S307, the control unit 180 transmits the radiation image to the information processing device 502. The information processing device 502 performs image processing, such as image correction, on the radiation image received from the control unit 180, and performs display control to display the processed radiation image on the display unit.

[0064] In step S308, the information processing device 502 receives radiation irradiation information received from the radiation generator 506 and displays the received irradiation information. By displaying the information, the user can confirm whether the intended irradiation was performed.

[0065] In step S309, the information processing device 502 transmits the radiographic image to the bone information calculation device 510. The bone information calculation device 510 calculates the bone information (bone mineral density, bone density) of the subject after user operations such as bone identification have been performed. In the DEXA method, the bone information calculation device 510 acquires two radiographic images with different energy distributions (first radiographic image, second radiographic image) and calculates the bone information of the subject identified based on user operations. The bone information of the subject includes at least one of bone mineral density and bone density.

[0066] In step S310, the results are registered in the database and the imaging is completed. As described above, by determining whether there was insufficient irradiation during BMD imaging, it becomes possible to calculate highly accurate bone information (bone mineral density and bone mineral density).

[0067] Figures 4A and 4B show examples of sequences for determining insufficient irradiation in DEXA imaging according to the first embodiment. Referring to Figures 4A and 4B, an example of a sequence in which the radiation generator 506, the synchronization control device 505, the radiography apparatus 100, and the information processing device 502 perform insufficient irradiation determination will be described. The radiography apparatus 100 is capable of performing a first radiography, in which one image is taken based on one irradiation permission, and a second radiography, in which two images are taken based on one irradiation permission.

[0068] In S401, the radiography apparatus 100 transmits imaging conditions, such as imaging parameters necessary for the operation of the synchronization control device 505, from the setting information received from the information processing device 502. The imaging parameters include, for example, the maximum number of irradiations when the exposure SW is held down, the maximum permitted irradiation time for a single radiation irradiation, and the preparation time from when the radiography apparatus 100 receives the irradiation permission request signal until it can transmit irradiation permission. The setting information transmitted from the information processing device 502 to the radiography apparatus 100 may include information indicating whether it is DEXA imaging (imaging for bone density measurement) or general radiography other than DEXA imaging. The imaging parameters transmitted from the radiography apparatus 100 to the synchronization control device 505 may include information indicating whether it is DEXA imaging (imaging for bone density measurement) or general radiography other than DEXA imaging. In DEXA imaging, two radiation irradiations are automatically performed at predetermined timings with one operation of the exposure switch, while in general radiography, one radiation irradiation is automatically performed at predetermined timings with one operation of the exposure switch. In general radiography, even if radiation irradiation is stopped midway, it is sufficient if the image can be evaluated; therefore, there is no need for the notification unit to display a warning or other notification if radiation irradiation is stopped midway.

[0069] However, in DEXA imaging, if radiation is stopped midway through either of the two radiation doses, it may become impossible to accurately acquire bone density information. Therefore, in DEXA imaging, if radiation is stopped midway through either of the two radiation doses, the notification unit of the information processing device 502 will issue a warning or other notification. An indicator may also be provided on the radiography device 100 as a notification unit for a warning display to inform the user of the possibility of insufficient radiation exposure.

[0070] In S402, the radiation generator 506 asserts an irradiation permission request signal based on a user operation such as pressing the exposure switch. That is, based on a user operation such as pressing the exposure switch, the radiation generator 506 transmits a signal to the synchronization control device 505 to activate the irradiation permission request signal.

[0071] In S403, when the irradiation permission request signal is asserted, the synchronization control device 505 transmits an irradiation permission request signal to the radiography device 100. Furthermore, the synchronization control device 505 monitors the time until it receives an irradiation permission signal from the radiography device 100. The synchronization control device 505 then starts measuring the timeout period. This is preferable in terms of reducing invalid exposure in cases where synchronization cannot be achieved due to a malfunction of the radiography device 100 or an abnormality in the communication path.

[0072] In S404, the radiography apparatus 100 transmits information about the processing time actually required for imaging preparation, that is, information about the preparation operation time, to the synchronization control device 505. The synchronization control device 505 may receive the information about the preparation operation time and use it as a threshold for determining a timeout.

[0073] In S405, once the radiography apparatus 100 has completed preparation for imaging, it enters a state where it can store radiation as an electric charge and transmits an irradiation permission signal to the synchronization control device 505. The radiography apparatus 100 may also notify the synchronization control device 505 of the preparation time (S404) information and the irradiation permission signal together. Notifying the synchronization control device 505 of the preparation time (S404) information and the irradiation permission signal (S405) together is preferable in terms of reducing communication processing time.

[0074] In S406, if the synchronization control device 505 receives an irradiation permission signal from the radiography device 100 within the timeout period, it asserts the irradiation permission signal to the radiation generator 506 for the maximum irradiation permission time during which radiation is irradiated. That is, if the synchronization control device 505 receives an irradiation permission signal from the radiography device 100 within the timeout period, it transmits a signal to the radiation generator 506 to activate the irradiation permission signal. The radiation generator 506 irradiates radiation upon assertion (activation) of the irradiation permission signal.

[0075] In S407, when the maximum permitted irradiation time is reached, the radiography apparatus 100 transmits an irradiation-not permitted signal to the synchronization control device 505 to stop irradiation. Furthermore, it reads out the charge to generate the first image and performs preparation driving for the acquisition of the second image. Performing preparation driving makes it possible to suppress the afterimage of the first image. The radiography apparatus 100 may also generate a correction image to subtract the dark current component, and acquiring the correction image at this timing is preferable in terms of reducing artifacts in the first image.

[0076] In S408, when the synchronization control device 505 receives a signal that irradiation is not permitted, it negates the irradiation permission signal to the radiation generator 506. That is, when the synchronization control device 505 receives a signal that irradiation is not permitted, it sends a signal to the radiation generator 506 to invalidate (inactivate) the irradiation permission signal. The radiation generator 506 stops irradiating radiation due to the negation (inactivation) of the irradiation permission signal. As long as the irradiation permission signal is asserted, there are no restrictions on the timing of starting or stopping radiation irradiation by the radiation generator 506.

[0077] In S409, the radiography apparatus 100 transmits a signal to the synchronization control device 505 granting permission for irradiation once the preparation operations before the second image are completed.

[0078] In S410, the same processing as in S406 is performed. That is, when the synchronization control device 505 receives an irradiation permission signal from the radiography device 100, it sends a signal to the radiation generator 506 to activate the irradiation permission signal. The radiation generator 506 irradiates with radiation upon assertion (activation) of the irradiation permission signal. However, in DEXA imaging, radiation with a different energy distribution is irradiated than in S406.

[0079] In S411, when the radiation generator 506 performs an irradiation stop operation due to user operation (such as releasing the exposure switch), it negates the irradiation permission request signal to the synchronization control device 505. In other words, when the radiation generator 506 performs an irradiation stop operation due to user operation, it sends a request signal to the synchronization control device 505 to invalidate (inactivate) the irradiation permission request signal.

[0080] In S412, when the irradiation permission request signal is negated, the synchronization control device 505 determines whether the time permitted for a single radiation irradiation has reached the maximum permitted irradiation time among the imaging parameters. If the irradiation permission request signal is negated before the permitted time for radiation irradiation has exceeded the maximum permitted irradiation time, the synchronization control device 505 determines that irradiation should be stopped and sends an irradiation stop signal to the radiography device 100. When the radiography device 100 receives the irradiation stop signal from the synchronization control device 505, it determines whether the radiation irradiation is insufficient based on a comparison of the radiation irradiation time to the radiography device 100 with the standard permitted irradiation time (maximum permitted irradiation time) for which radiation irradiation was permitted. If the radiation irradiation time ends before the preset standard permitted irradiation time (maximum permitted irradiation time), the radiography device 100 determines that the irradiation is insufficient and sends the irradiation insufficiency determination result to the information processing device 502. The information processing device 502 displays a warning upon notification of insufficient irradiation. Furthermore, the determination of insufficient irradiation is not limited to the radiography device 100. If the irradiation permission request signal is negated before the permitted irradiation time has elapsed, the information processing device 502 may determine that there is insufficient irradiation and display a warning on the display unit.

[0081] In S413, the synchronization control device 505 negates the irradiation permission signal if the irradiation permission request signal is negated. That is, if the irradiation permission request signal is negated before the maximum irradiation permission time has elapsed (S411), the synchronization control device 505 sends a signal to the radiation generator 506 to invalidate (inactivate) the irradiation permission signal. The radiation generator 506 stops irradiating radiation due to the negation (inactivation) of the irradiation permission signal. It is preferable for the radiation generator 506 to stop irradiating radiation based on user operation before the irradiation permission signal is negated, in terms of avoiding unnecessary exposure.

[0082] In S414, when the maximum storage time is reached, the radiography apparatus 100 sends a signal to the synchronization control device 505 indicating that irradiation is not permitted and performs a charge readout operation to generate the second image. Then, in S415, the radiography apparatus 100 sends a termination signal to the synchronization control device 505 instructing it to end the imaging, and terminates the processing sequence in DEXA imaging.

[0083] Figure 10 shows an example sequence in general radiography, which differs from DEXA radiography according to the first embodiment. In DEXA radiography, as explained in Figures 4A and 4B, two radiation exposures are automatically performed at predetermined timings with a single operation of the exposure switch, whereas in general radiography, one radiation exposure is performed at a predetermined timing with a single operation of the exposure switch (S401 to S408 below). Then, in S409, the radiography apparatus 100 sends an end signal to the synchronization control device 505 instructing it to end the radiography, thus ending the processing sequence in general radiography. In general radiography, even if the radiation exposure stops midway, it is sufficient if the image can be evaluated, so the notification unit does not display a warning or other notification as in DEXA radiography, even if the radiation exposure stops midway.

[0084] Figure 6 is a diagram showing an example of DEXA imaging operation in a radiography apparatus according to the first embodiment. An example of operation of the radiography apparatus 100 will be described with reference to Figure 6. This operation is performed by the cooperation of a control unit 180 that controls the drive circuit 150 and the readout circuit 160 in the radiography apparatus 100, and a signal processing unit 170. In Figure 6, "radiation" indicates whether or not radiation is being irradiated to the radiography apparatus 100. A low state indicates that radiation is not being irradiated, and a high state indicates that radiation is being irradiated.

[0085] "Vg1" to "Vgn" indicate the drive signals supplied from the drive circuit 150 to the multiple drive lines 110. "Vgk" corresponds to the drive line 110 of the kth row (k = 1, ..., total number of drive lines). φSH indicates the level of the signal supplied to the sample-and-hold circuit SH of the amplification unit 161. φR indicates the level of the signal supplied to the differential amplifier circuit AMP of the amplification unit 161.

[0086] At time t61, the control unit 180 starts a reset operation for multiple pixels. The reset operation is an operation to remove the charge accumulated in the conversion element of each pixel, and specifically involves supplying a drive signal to the drive line 110 to make the switch element of each pixel conductive. The control unit 180 resets each pixel connected to the first row of drive lines 110 by controlling the drive circuit 150. Subsequently, the control unit 180 resets each pixel connected to the second row of drive lines 110. The control unit 180 repeats this operation up to the last row of drive lines 110. After completing the reset operation for the last row of drive lines 110, the control unit 180 repeats the reset operation again starting from the first row of drive lines 110.

[0087] At time t62, the control unit 180 receives a start request signal (irradiation permission request signal) from the synchronization control device 505. In response to the receipt of the start request signal, the control unit 180 performs a reset operation up to the last row and then finishes the reset operation. The control unit 180 may also finish the reset operation before performing the reset operation up to the last row and proceed to the next process. For example, if the control unit 180 receives a start request signal while resetting the drive line 110 of the kth row, it may proceed to the next process without performing a reset operation on the drive lines 110 from the k+1th row onward. In this case, steps that may occur in the radiation image may be reduced by adjusting the drive for acquiring the radiation image or by performing image processing on the radiation image. If the start request signal goes low between time t62 and t63, such as by releasing the exposure SW, the synchronization control device 505 determines that irradiation has been interrupted without any irradiation and notifies the radiation imaging device 100 and the information processing device 502 that irradiation has been interrupted without any irradiation.

[0088] At time t63, the control unit 180 transmits a start signal (irradiation permission signal) to the radiation generator 506 via the synchronization control device 505. After transmitting the start signal, the control unit 180 controls the system to accumulate charge without performing the read operation described above. If the start request signal goes low between times t62 and t63, such as when the exposure switch is released, the synchronization control device 505 determines that irradiation has been interrupted and transmits an irradiation stop signal to the radiography device 100. If the radiography device 100 receives the irradiation stop signal from the synchronization control device 505 before reaching the standard permission time (maximum irradiation permission time), it determines that there has been insufficient radiation exposure and transmits the irradiation insufficiency determination result to the information processing device 502.

[0089] At time t64, the radiation generator 506 terminates radiation irradiation in response to irradiation stop control from the synchronization control device 505. The control unit 180 reads the charge accumulated in the imaging pixel 101 and generates an image. It also performs preparatory operations for generating a second radiation image with a different energy distribution. The preparatory operations are the same as those described above at t61 to t63.

[0090] At time t65, the control unit 180 transmits a start signal (irradiation permission signal) to the radiation generator 506 when the imaging preparation unit operation is complete.

[0091] Between times t66 and t67, charge accumulation and image generation are performed in the same manner as between t64 and t65. At t67, if the start request signal (irradiation permission request signal) goes low, the synchronization control device 505 can determine that the irradiation has ended without interruption. As described above, if the start request signal goes low during the period between times t62 and t66, the synchronization control device 505 determines that the irradiation has been interrupted and sends an irradiation stop signal to the radiography device 100. When the radiography device 100 receives the irradiation stop signal from the synchronization control device 505, it determines that the irradiation is insufficient and sends the irradiation insufficiency determination result to the information processing device 502. By sending the irradiation insufficiency determination result to the information processing device 502 and displaying a warning, it is possible to notify that the calculation accuracy of bone information (bone mineral density, bone density) may be reduced. Furthermore, as will be described later, changing the content of the warning display depending on the timing when the start request signal goes low is preferable in terms of dose reduction and examination / diagnosis time.

[0092] Figure 7 illustrates the principle for calculating bone density using the DEXA method according to the first embodiment. Generally, when radiation passes through an object, the radiation is attenuated by interaction with the object. In radiation images acquired by an FPD, the radiation intensity integrated with respect to the depth direction of the object is reflected as a pixel value, so the pixel value I in the radiation image after transmission through the object is expressed by the following equation 1.

[0093]

[0094] Here, I ０ : Pixel value in a radiographic image without a subject, μ: Mass attenuation coefficient [cm] ２ / g], σ: areal density [g / cm ２ This indicates [...].

[0095] The mass attenuation coefficient depends on the substance (atomic number of the substance) and the energy of the radiation, and therefore varies depending on two different radiation energies and the substance (e.g., bone and soft tissue). Note that the energy depends on monochromatic energy, so in cases of attenuation involving multiple energies, such as in a radiation spectrum, the above formula does not strictly match.

[0096] When taking radiographic images for two different radiation energies (hereinafter referred to as low energy and high energy), the following Equation (2) holds.

[0097]

[0098] Each subscript represents L: low energy, H: high energy, B: bone, and S: soft tissue. Also, R represents the attenuation rate (transmittance) of energy. The density of the substance to be determined by the radiation imaging system 500 of the first embodiment is the bone density σ Ｂ and, in the bone information calculation device 510, by solving the above simultaneous equations, the bone density σ Ｂ can be obtained by the following Equation (3). As a typical method for solving a non-linear simultaneous equation, the bone information calculation device 510 can perform an analysis using, for example, the Newton-Raphson method.

[0099]

[0100] Here, α is a subtraction coefficient and K is a calibration coefficient, which are coefficients determined based on calibration (calibration processing) described later. The subtraction coefficient α is the ratio of the mass attenuation coefficient μ ＨＳ of the high-energy soft tissue to the mass attenuation coefficient μ <* ＬＳ of the low-energy soft tissue, and is a coefficient obtained by dividing the mass attenuation coefficient μ ＨＳ of the high-energy soft tissue by the mass attenuation coefficient μ ＬＳ of the low-energy soft tissue.

[0101] To obtain the difference in transmittance (R Ｈ - R Ｌ ) of bone and soft tissue for low-energy and high-energy radiation, first, it is necessary to match the transmittance of the soft tissue part at low energy to the output of the soft tissue part at high energy, and the subtraction coefficient α obtained by taking the ratio of the mass attenuation coefficient μ ＨＳ of the high-energy soft tissue to the mass attenuation coefficient μ ＬＳ of the low-energy soft tissue is used. The difference in transmittance (RＨ -αR Ｌ ) does not have the dimension of bone density, so the calibration information (calibration coefficient K) obtained in advance by calibration using the QC phantom described later is used as the difference in transmittance (R Ｈ -αR Ｌ Bone information (bone density) can be obtained by multiplying by ).

[0102] As mentioned above, bone density measurement requires calibration using a bone density calibration phantom (Quality Control phantom, hereinafter referred to as "QC phantom") with a known bone density. The QC phantom contains bone equivalent material of a known density, and the bone information calculation device 510 calculates the calibration coefficient K in advance by calibration using the QC phantom, and then calibrates the output value obtained from the radiography device 100 with the calibration coefficient K to determine the bone density. An example of a QC phantom is the "table-type phantom T-1 (hereinafter sometimes referred to as T1 phantom)" described in "JIS Z 4930 Performance evaluation phantom for radiographic bone density measurement".

[0103] An example of calculating the calibration coefficient K using a T1 phantom is shown below. The T1 phantom contains three bone-equivalent materials with known densities, which are 0.7, 1.0, and 1.3 [g / cm³]. ２ Figure 7 shows the relationship between the difference in transmittance between bone and soft tissue and bone density values ​​for radiation at different energy levels (low energy, high energy). The difference in transmittance between bone and soft tissue for low energy and high energy radiation (R) was calculated based on the calculation principle of bone density using the DEXA method. Ｈ -αR Ｌ The relationship between (R) and bone density is linearly approximated as shown in Figure 7 to calculate the calibration coefficient K. In the example in Figure 7, the difference in transmittance between bone and soft tissue for low-energy and high-energy radiation (R) Ｈ -αR Ｌ The horizontal axis (x-axis) shows the bone density value [g / cm³]. ２The vertical axis (y-axis) shows the values. Plotting the three known densities in the T1 phantom and linearly approximating the three points, the linear approximation is obtained as y = 15.891 * x - 0.1. The calibration coefficient K obtained by the linear approximation is 15.891.

[0104] Figure 8 shows an example of notification in the event of insufficient irradiation according to the first embodiment. Referring to Figure 8, an example of the display of the warning screen (first notification example) when irradiation stops in the sequence described in Figures 4A and 4B before the maximum permitted irradiation time has elapsed will be explained. In Figure 6, the start request signal (irradiation permission request signal) is in the High state during the period from time t64 to t66, but if the start request signal (irradiation permission request signal) becomes Low during this period, radiation irradiation stops, resulting in a state of insufficient irradiation.

[0105] The information processing device 502 displays radiation images received from the control unit 180 of the radiography apparatus 100 and irradiation information received from the radiation generator 506 on its display unit. The warning display on the information processing device 502's display unit shows the first radiation image 801 (first radiation image) and irradiation information (tube voltage: A, irradiation time: B, tube current: C, mAs: D) for calculating bone density using the DEXA method, and the second radiation image 802 (second radiation image) and irradiation information (tube voltage: a, irradiation time: b, tube current: c, mAs: d). Displaying two radiation images for calculating bone density using the DEXA method, along with the irradiation information for each radiation image, is suitable for determining insufficient irradiation.

[0106] The control unit 180 of the radiography apparatus 100 notifies the information processing device 502 of the possibility of insufficient radiation exposure when it determines that radiation exposure is insufficient. The information processing device 502 displays a warning display 803 on its display unit to inform the user of the possibility of insufficient radiation exposure. When displaying the warning display 803 on the display unit, a display prompting confirmation of the radiation exposure information may also be displayed. In addition, a re-shoot button 804 and a cancel button 805 to stop shooting may be provided to facilitate re-shooting. When re-shooting is performed using the re-shoot button 804, for example, it is preferable from the viewpoint of reducing ineffective exposure to only take the second radiation image which is insufficient. Which radiation image to re-shoot can be specified by input from the input unit of the information processing device 502. Furthermore, the radiography apparatus 100 may be provided with an indicator for a warning display to inform the user of the possibility of insufficient radiation exposure. The display color of the warning display on the indicator may be changed, or the pattern of the warning display may be changed.

[0107] Figure 9 shows an example of notification in the event of insufficient irradiation according to the first embodiment. During the period from time t64 to t66 in Figure 6, the start request signal (irradiation permission request signal) is in the High state. If the start request signal (irradiation permission request signal) becomes Low during this period, radiation irradiation is stopped, and an example of the display of the warning screen when an insufficient irradiation occurs (second notification example) will be explained with reference to Figure 9.

[0108] The information processing device 502 displays radiation images received from the control unit 180 of the radiography apparatus 100 and irradiation information received from the radiation generator 506 on its display unit. The warning display on the information processing device 502's display unit shows the first radiation image 901 and irradiation information (tube voltage: A, irradiation time: B, tube current: C, mAs: D) for calculating bone density using the DEXA method, and the second radiation image 902 and irradiation information (tube voltage: a, irradiation time: b, tube current: c, mAs: d). Displaying two radiation images for calculating bone density using the DEXA method, along with the irradiation information for each radiation image, is suitable for determining insufficient irradiation.

[0109] The control unit 180 of the radiography apparatus 100 notifies the information processing device 502 of the possibility that radiation has not been applied if it determines that no radiation has been applied. The information processing device 502 displays a warning display 903 on the display unit to inform the user of the possibility that no radiation has been applied. When displaying the warning display 903 on the display unit, a display prompting confirmation of the radiation application information may also be displayed. Figure 8 shows that there is a possibility of invalid exposure due to irradiation, whereas Figure 9 shows that there is no exposure, so this can be useful information in terms of managing the exposure of the subject. In addition, a retake button 904 and a cancel button 905 to stop shooting may be provided to facilitate retakes. When retaking using the retake button 904, it is sufficient to start from the first radiography image in which no radiation was applied to the subject. Furthermore, an indicator for a warning display to inform the user of the possibility that no radiation has been applied may be provided on the radiography apparatus 100. The display color of the warning display on the indicator may be changed, or the pattern of the warning display may be changed.

[0110] In another embodiment, the information processing device 502 may compare the irradiation execution information (A to D, a to d) with the irradiation execution information acquired in advance during calibration imaging using the QC phantom, and display a warning if the difference in the irradiation execution information falls outside a certain range.

[0111] The information processing device 502 compares the irradiation information (reference irradiation information) acquired during calibration using the QC phantom with the first and second irradiation information acquired when acquiring two radiographic images for bone density calculation using the DEXA method. The two radiographic images are radiographic images taken by irradiation with radiation at different energy levels (low energy and high energy). The information processing device 502 acquires the first irradiation information (A to D) at the time of the first radiation irradiation and the second irradiation information (a to d) at the time of the second radiation irradiation. The information processing device 502 may then display a warning if, for example, the difference between at least one of the irradiation information (A to D) and the QC phantom irradiation information (reference irradiation information) is outside a certain range. Note that the processing related to the warning display is not limited to the information processing device 502, but may also be performed by the bone information calculation device 510.

[0112] In another embodiment, the bone information calculation device 510 may compare the pixel values ​​of the bone or soft tissue at the time of subject imaging with the pixel values ​​of the bone or soft tissue acquired in advance during calibration imaging using the QC phantom, and display a warning if the difference in pixel values ​​falls outside a certain range.

[0113] The bone information calculation device 510 compares the pixel values ​​of bone or soft tissue (reference pixel values) obtained during calibration using the QC phantom with the pixel values ​​of bone or soft tissue obtained based on two radiographic images for calculating bone density using the DEXA method. The bone information calculation device 510 may then display a warning if, for example, the difference between the pixel values ​​of bone or soft tissue obtained based on the radiographic images and the pixel values ​​of bone or soft tissue from the QC phantom (reference pixel values) falls outside a certain range.

[0114] According to each of the embodiments described above, it becomes possible to notify of insufficient radiation exposure. This makes it possible to acquire bone information of the subject with high accuracy.

[0115] (Second Embodiment) (Configuration of the Radiology Information System RIS) Figure 11 shows the configuration of the Radiology Information System RIS of the embodiment. The Radiology Information System RIS irradiates a subject with radiation such as X-rays and acquires a radiographic image of the subject by detecting the radiation that has passed through the subject. The Radiology Information System RIS may include, for example, a radiation source 113, an exposure control device 114, a control device 112 (hereinafter also referred to as the "imaging control device"), and a radiographic device 100. The configuration of the Radiology Information System RIS will be the same in the second to fourth embodiments described below.

[0116] The exposure control device 114 sets radiation irradiation conditions (e.g., tube current (mA), tube voltage (kV), etc.) by communicating with the radiation source 113. Based on the operator's input via the user interface, the exposure control device 114 performs exposure control to generate radiation from the radiation source 113 in response to the exposure command transmitted from the control device 112.

[0117] The control device 112 controls the radiography apparatus 100, acquires radiographic images from the radiography apparatus 100, performs image processing on the acquired radiographic images, and functions as an image processing device for displaying them on a display device (display unit). The control device 112 also transmits exposure commands to the exposure control device 114 and controls the exposure control device 114. The control device 112 may include, for example, input devices such as a keyboard, pointing device (e.g., mouse), or touch panel (not shown) as a user interface, a display device such as a liquid crystal display (not shown), or a storage device such as a hard disk drive or solid-state drive (SSD) (not shown). Each device may be connected by a wired or wireless network.

[0118] The radiography apparatus 100 detects radiation irradiated from the radiation source 113 that has passed through a subject (not shown) and outputs image data corresponding to the radiation. The image data can also be referred to as, for example, an image, a medical image, or a radiographic image. The radiography apparatus 100 may include an imaging unit 104 for capturing radiographic images, a communication unit 109 for communicating with the control device 112, a control unit 106 for controlling the imaging unit 104, and a power supply unit 110 for supplying power to the imaging unit 104. The control unit 106 includes a drive control unit 107 for performing the main control of the imaging operation and a standby time monitoring unit 108 for monitoring the standby time when switching imaging modes.

[0119] The control unit 106 controls the drive control unit 107 and the standby time monitoring unit 108 based on control information received from the control device 112 via the communication unit 109. The drive control unit 107 supplies drive signals to the scanning circuit 102 and the readout circuit 103 according to control signals from the control unit 106. The drive signal is a signal to turn on a switch element (not shown) included in the pixel to be driven in the pixel array 101. The switch element turns on with a high-level signal and turns off with a low-level signal. When a drive signal is supplied to a pixel, the signal stored in the conversion element of that pixel becomes readable by the readout circuit 103.

[0120] The standby time monitoring unit 108 is equipped with a timer for measuring the passage of time and starts measuring (counting down) the standby time set based on the control information of the control device 112. Different standby times may be set based on various shooting modes and the shooting order for each shooting mode.

[0121] Furthermore, the radiography apparatus 100 may include an analysis unit 111 that analyzes images output from the imaging unit 104, and a processing unit 105 that performs calculations on the images output from the imaging unit 104. The processing unit 105, control unit 106 (including the drive control unit 107 and the standby time monitoring unit 108), and analysis unit 111 included in the radiography apparatus 100 may be implemented by the CPU (central processing unit) of the computer equipped in the radiography apparatus 100, or by a dedicated or general-purpose processor executing a program. Alternatively, they may be configured using hardware such as an FPGA (field programmable gate array) or ASIC (application specific integrated circuit). Also, some components of the radiography apparatus 100 may be incorporated into the control device 112, or the radiography apparatus 100 and the control device 112 may be integrated. For example, in the example shown in Figure 11, the analysis unit 111 and the processing unit 105 may be incorporated into the control device 112.

[0122] The imaging unit 104 may include, for example, a pixel array 101, a scanning circuit 102, and a readout circuit 103. The pixel array 101 is configured by arranging multiple pixels PIX in two dimensions to form multiple rows and multiple columns. The scanning circuit 102 scans multiple rows of the pixel array 101 according to a selected mode from among multiple modes (imaging modes). The readout circuit 103 reads the signals accumulated in the pixels PIX from the pixel array 101. More specifically, the readout circuit 103 reads the signals from the pixels PIX of the row selected by the scanning circuit 102 from among the multiple rows of the pixel array 101. Reading signals from the pixel array 101 means processing the signals output from the pixel array 101 and outputting a signal corresponding to those signals.

[0123] Figure 12 illustrates the relationship between switching between imaging modes and the first and second waiting times in the radiography system of this embodiment. In Figure 12, the waiting time when switching from the first imaging mode to the second imaging mode is illustrated as an example, representing multiple imaging modes with different irradiation doses (radiation exposure doses).

[0124] As mentioned above, after taking a radiographic image, afterimages may remain depending on the radiation dose, which can lead to degradation of subsequent images. Here, the first waiting time is defined as the time until the amount of afterimage after taking a radiographic image falls below the upper limit of the permissible limit. Here, the upper limit of the permissible amount of afterimage is a parameter set in advance according to the shooting mode. The upper limit for general radiography other than BMD radiography may be set to a larger value than the upper limit for BMD radiography. Since BMD radiography is more sensitive to the effects of afterimages than general radiography, when general radiography is performed before BMD radiography, the upper limit for general radiography may be set to a larger value than the upper limit for BMD radiography in order to reduce the amount of afterimages.

[0125] The starting point of the first waiting time is the start of the shooting operation in the first shooting mode (the start of radiation irradiation), and the waiting time monitoring unit 108 measures a countdown toward the completion of the first waiting time while in the shooting operation state. The waiting time monitoring unit 108 may continue measuring the countdown toward the completion of the first waiting time during the preparation time of the shooting mode after the shooting mode has been changed (for example, the second shooting mode) following the completion of shooting in the first shooting mode. That is, after shooting in the first shooting mode, the shooting mode may be changed, and the countdown measurement of the first waiting time may continue during the preparation time of the changed second shooting mode (the time from the completion of the shooting mode switch until before the transition to the shooting-ready state in the second shooting mode). The first waiting time is completed (ended) when the amount of afterimage after shooting in the first shooting mode falls below the upper limit of the allowable amount, as measured by the waiting time monitoring unit 108. Note that during the preparation time of the second shooting mode before the completion (ended) of the first waiting time, the shooting state is not possible.

[0126] The first waiting period begins when the exposure switch (SW) is pressed and radiation irradiation starts in the first imaging mode. The end time of the first waiting period may vary depending on the combination of the first and second imaging modes, and the timing of the start of radiation irradiation in the first imaging mode.

[0127] The longer the first waiting time, the greater the radiation dose in the first shooting mode and the higher the image quality required for the image captured in the second shooting mode. However, if the radiation imaging device 100 has not performed any shooting operations since startup, the conversion elements of each pixel are in a state where no charge signals have accumulated (remained), or the accumulated charge signals have been sufficiently reduced, so this first waiting time may be unnecessary.

[0128] In this embodiment, the first waiting time is the time from the start of radiation irradiation during the first shooting mode until the first image error information, which may be included in the radiation image acquired by shooting and which has the characteristic of decaying over time, falls below a predetermined value. The first image error information is the amount of afterimage that may be included in the radiation image. The first waiting time is set to a different time depending on the order of the first shooting mode and the second shooting mode.

[0129] Furthermore, it is known that the offset component changes transiently immediately after the shooting mode is changed. Since the transient change lasts for a relatively long time, even if an offset image is prepared for offset correction during the transient state, it is difficult to perform correct offset correction, and shading may be superimposed on the output image.

[0130] Here, the second waiting time is defined as the time it takes for the shading caused by transient changes after a change in shooting mode to fall below the upper limit of the acceptable limit. Here, the upper limit of the acceptable limit for the amount of shading is a parameter that is pre-set in accordance with the shooting mode.

[0131] The standby time monitoring unit 108 measures the second standby time during the preparation time of the changed shooting mode (for example, the second shooting mode) after the shooting mode has been changed. The starting point of the second standby time is when the switching of the shooting mode is completed, and the standby time monitoring unit 108 measures the countdown of the second standby time during the preparation time of the changed second shooting mode (the time from when the switching of the shooting mode is completed until before the transition to the shooting-ready state in the second shooting mode). The standby time monitoring unit 108 measures the second standby time until the shading due to the transient change after shooting in the first shooting mode falls below the upper limit of the allowable value. Note that during the preparation time of the second shooting mode before the second standby time is completed, the shooting state is not possible.

[0132] As described above, the first waiting period is completed (ended) within the preparation time for the second shooting mode. The shooting preparation time also ends upon completion (end) of both the first and second waiting periods. In other words, upon completion (end) of both the first and second waiting periods, the shooting unit 104 of the radiography apparatus 100 transitions from a non-shooting state to a shooting-ready state.

[0133] In this embodiment, the second waiting time is the time from the completion of the switch from the first shooting mode to the second shooting mode until the second image error information, which may be included in the radiation image acquired by shooting and has the characteristic of decaying over time, falls below a predetermined value. The second image error information is the amount of shading that may be included in the radiation image. The second waiting time is set to a different time depending on the order in which the first shooting mode and the second shooting mode are used.

[0134] The second waiting period begins when the imaging unit 104 receives an instruction to switch from the first imaging mode to the second imaging mode and has completed the switch to the second imaging mode. The timing at which the second waiting period is completed (ends) may vary depending on the imaging conditions and required image quality in the second imaging mode. Here, the time when the switch to the second imaging mode is completed means when the imaging conditions for the second imaging mode are set in the control device 112 and the radiography apparatus 100 is ready for imaging based on instructions from the control device 112.

[0135] Because the attenuation characteristics that show the change in the amount of afterimage over time (e.g., the first attenuation characteristic) and the attenuation characteristics that show the transient change in the amount of shading (e.g., the second attenuation characteristic) are different, when switching from the first shooting mode to a second shooting mode that is different from the first shooting mode, it may be necessary to complete (end) both the first and second waiting times. The higher the image quality required for the image captured in the second shooting mode, which is the next shooting mode after the first shooting mode, the longer the second waiting time may be. Since the first and second waiting times are waiting times required only when switching to a different shooting mode, if the first and second shooting modes are of the same type, the second waiting time is not required. In this case, only the completion of the first waiting time may be necessary.

[0136] In other words, in order to obtain higher-quality radiation images in the second shooting mode, the start and end times of measurement during the first and second waiting periods can be set by at least one of the following: the combination of the first and second shooting modes, the radiation irradiation timing during shooting in the first shooting mode, or the timing of the completion of the switch from the first to the second shooting mode. Furthermore, in order to transition to a state where shooting is possible in the second shooting mode, both the first and second waiting periods must be completed (finished), that is, the shooting waiting period must be completed (finished) to satisfy the requirements of the first and second waiting periods.

[0137] The system monitors the first and second waiting periods, and when both waiting periods have elapsed, it transitions to a state where shooting is possible in the second shooting mode. Therefore, before the completion of the first and second waiting periods, shooting in the second shooting mode is not possible. After the completion of the first and second waiting periods, shooting in the second shooting mode becomes possible.

[0138] (Processing Flow) Figure 13 is a diagram illustrating the process of switching from the first shooting mode to the second shooting mode, using multiple shooting modes with different irradiation doses (radiation exposure doses).

[0139] In step S301, imaging in the first imaging mode is started, and in step S302, imaging in the first imaging mode is started when the operator presses the exposure switch (SW), and radiation is emitted from the radiation source 113. At the moment when the radiation imaging device 100 detects the radiation emitted from the radiation source 113, in step S303, the standby time monitoring unit 108 starts counting down the first standby time.

[0140] In step S304, after the shooting in the first shooting mode is completed, in step S305, the control unit 106 of the radiography apparatus 100 receives an instruction from the control device 112 to switch from the first shooting mode to the second shooting mode.

[0141] In step S306, the drive control unit 107 controls the shooting unit 104 to switch to the second shooting mode based on the switching instruction to the second shooting mode acquired by the control unit 106. In step S306, once the switching from the first shooting mode to the second shooting mode is complete, in step S307, the standby time monitoring unit 108 starts counting down the second standby time. Starting from the time when the switching of the shooting mode is completed (S306), the standby time monitoring unit 108 measures the countdown of the second standby time during the preparation time for the changed second shooting mode.

[0142] In step S308, the standby time monitoring unit 108 determines whether the first standby time and the second standby time have been completed. If the countdown for the first standby time and the second standby time has not been completed (S308-NO), the standby time monitoring unit 108 continues counting down the first standby time and the second standby time. If either the first standby time or the second standby time has been completed (finished), the standby time monitoring unit 108 should continue monitoring the countdown of the other standby time that has not been completed (finished).

[0143] The standby time monitoring unit 108 maintains the shooting preparation state (shooting unavailable state) until the countdown for the first standby time, the second standby time, and all standby times is completed (S308-NO). Once the first standby time and the second standby time are completed (S308-YES), in step S309, the drive control unit 107 performs transition control to enable shooting in the second shooting mode for the shooting unit 104.

[0144] The control unit 106 may also perform display control to display the result of the countdown measurement by the standby time monitoring unit 108 on a display device (display unit) such as a display. In addition, the control unit 106 may notify the user that the countdown measurement by the standby time monitoring unit 108 has been completed by displaying it on a display device (display unit) not shown, or by generating a sound from a sound-generating device (sound-generating unit) such as a speaker.

[0145] According to this embodiment, when shooting continuously using different shooting modes, shooting is performed based on the completion determination of the waiting time in each shooting mode, making it possible to acquire images of excellent quality that can be used for diagnosis, etc., in the shortest possible time.

[0146] (Third Embodiment) Figure 14 is a diagram showing an example of the first and second waiting times in the radiography system of the third embodiment. In the third embodiment, the first and second waiting times shown in Figure 14 are illustrative examples, with the first or second shooting mode being an X-ray shooting mode having two different energy spectra (BMD shooting mode) or a still image shooting mode. The table shown in Figure 14 is stored in a memory unit (not shown), and by referring to the table in Figure 14, it is possible to set the waiting times corresponding to the combination of shooting modes.

[0147] For the diagnosis of osteoporosis and other conditions, a measurement method called BMD (Bone Mineral Density) is used. As a method for measuring bone mineral density in bone, dual-energy X-ray absorptiometry (DXA, hereinafter also referred to as the DXA method) is known, which uses two types of radiation (X-rays) with different energy distributions to measure bone density from the difference in X-ray absorption coefficients between soft tissue and bone tissue. In this embodiment, the imaging mode for measuring bone density using the DXA method is called the BMD imaging mode. Furthermore, as an example of a general X-ray imaging mode that uses radiation with a single energy distribution, which is different from the imaging mode for measuring bone density, the still image imaging mode will be explained.

[0148] Figure 16 is a schematic diagram (ST61, ST62) illustrating the relationship between switching between imaging modes and the first and second waiting times in a radiography system of the third embodiment. ST61 in Figure 16 schematically illustrates the relationship between the first and second waiting times when different types of imaging are performed in the first and second imaging modes. ST62 in Figure 16 schematically illustrates the relationship between the first and second waiting times when the same type of imaging is performed in the first and second imaging modes.

[0149] The shaded areas schematically show how afterimages or shading decrease over time. For example, let's consider the case shown in Figure 14, where the first shooting mode is the general shooting mode (still image shooting mode) and the second shooting mode is the BMD shooting mode (when performing different types of shooting).

[0150] In order to perform shooting in the second shooting mode (BMD shooting mode) as early as possible, as shown in ST61, it is necessary to wait for a predetermined time (e.g., 30 seconds) from the exposure timing of the first shooting mode (exposure SW pressed) until the countdown of the first waiting time begins and the first waiting time is completed. Furthermore, after the end of the first shooting mode and after switching to the second shooting mode, it is necessary to wait for a predetermined time (e.g., 3.3 seconds) from the countdown of the second waiting time begins and the second waiting time is completed.

[0151] Then, based on measurements by the standby time monitoring unit 108, the system remains in a shooting preparation state (shooting impossible state) until the countdown of the first standby time, the second standby time, and all standby times is completed. Once the first standby time and the second standby time are completed, the drive control unit 107 performs transition control to enable shooting in the second shooting mode (BMD shooting mode).

[0152] The first standby time (e.g., 30 seconds) when the first shooting mode is set to still image shooting mode may be longer than the first standby time (e.g., 10 seconds) when the first shooting mode is set to BMD shooting mode. This is because the radiation dose in the first shooting mode is higher in still image shooting mode than in BMD shooting mode, and the image quality required for the captured image in the second shooting mode is higher in BMD shooting mode than in still image shooting mode.

[0153] Furthermore, the second standby time (3.0 seconds) when the second shooting mode is set to still image shooting mode may be shorter than the second standby time (3.3 seconds) when the second shooting mode is set to BMD shooting mode. The reason is that, as mentioned above, the image quality required for images captured in the second shooting mode is higher in BMD shooting mode than in still image shooting mode. Here, since the second standby time requires the camera to be in a standby state before shooting in the second shooting mode, by issuing a command to switch shooting modes immediately after shooting in the first shooting mode is completed, and starting the countdown for the second standby time after the switch is complete, it is possible to transition to a state where shooting in the second shooting mode is possible with a shorter standby time, starting from shooting in the first shooting mode (ST61).

[0154] Furthermore, if the first shooting mode is BMD shooting mode and the second shooting mode is also BMD shooting mode, and the first and second shooting modes are of the same type, as shown in Figure 14, the second waiting time will be "none" (zero), and as shown in ST62 in Figure 16, it is sufficient to wait only until the first waiting time is completed. Similarly, if the first and second shooting modes are of the same type, such as the first shooting mode being still image shooting mode and the second shooting mode being still image shooting mode, as shown in ST62 in Figure 16, it is sufficient to wait only until the first waiting time is completed.

[0155] According to this embodiment, when shooting continuously using different shooting modes, shooting is performed based on the completion determination of the waiting time in each shooting mode, making it possible to acquire images of excellent quality that can be used for diagnosis, etc., in the shortest possible time.

[0156] (Fourth Embodiment) Figures 15A and 15B are flowcharts illustrating the processing flow when a command to switch to a third shooting mode, which is different from the second shooting mode, is received while the system is waiting after switching from the first shooting mode to the second shooting mode.

[0157] Similar to Figure 13, after taking a picture in the first shooting mode, an instruction to switch to the second shooting mode is received, and the countdown for the first and second waiting times begins (S501-S507). That is, in step S501, shooting in the first shooting mode begins, and in step S502, when the operator presses the exposure switch (SW), shooting in the first shooting mode begins and radiation is emitted from the radiation source 113. At the moment the radiation imaging device 100 detects the radiation emitted from the radiation source 113, in step S503, the waiting time monitoring unit 108 begins counting down the first waiting time.

[0158] In step S504, after the imaging in the first imaging mode is completed, in step S505, the control unit 106 of the radiography apparatus 100 receives an instruction from the control device 112 to switch from the first imaging mode to the second imaging mode.

[0159] In step S506, the drive control unit 107 controls the shooting unit 104 to switch to the second shooting mode based on the switching instruction to the second shooting mode acquired by the control unit 106. In step S506, once the drive control unit 107 has completed switching from the first shooting mode to the second shooting mode, in step S507, the standby time monitoring unit 108 starts counting down the second standby time.

[0160] In step S508, during the countdown of the second waiting time, the control unit 106 of the radiography apparatus 100 determines whether it has received an instruction from the control device 112 to switch to a third shooting mode different from the second shooting mode. If, in the determination in step S508, an instruction to switch to a third shooting mode different from the second shooting mode has been newly received (S508-YES), in step S509, the waiting time monitoring unit 108 sets the third waiting time based on the combination of the first shooting mode and the third shooting mode by referring to a table (for example, Figure 14). The third shooting mode different from the second shooting mode is different in comparison with the second shooting mode, and the third shooting mode may be the same as the first shooting mode. That is, the first shooting mode may be general radiography, the second shooting mode may be BMD radiography, and then, during the measurement of the first and second waiting times, the third shooting mode may be further switched to general radiography, which is different from the BMD radiography of the second shooting mode. In such cases, the control unit 106 cancels the preparation for BMD shooting in the second shooting mode and, after general shooting in the first shooting mode, performs preparation for shooting in the third shooting mode (preparation for general shooting).

[0161] For example, if general shooting is performed in the first shooting mode and BMD shooting is performed in the second shooting mode, according to the table in Figure 14, the second waiting time is, for example, 3.3 seconds.

[0162] On the other hand, if general shooting is performed in the first shooting mode, and a shooting mode switching instruction is received during preparation for shooting in the second shooting mode, and general shooting is performed in the third shooting mode, the second waiting time (third waiting time) is, for example, 3.0 seconds, according to the table in Figure 14. The waiting time monitoring unit 108 sets the third waiting time (for example, 3.0 seconds) based on the combination of the first shooting mode and the third shooting mode by referring to the table in Figure 14. If the first waiting time has already elapsed when the third waiting time is set based on the combination of the first shooting mode and the third shooting mode, the waiting time monitoring unit 108 determines that the first waiting time has been completed. Also, if the first waiting time is still being measured when the third waiting time is set, the waiting time monitoring unit 108 stops counting down the first waiting time.

[0163] In step S510, the standby time monitoring unit 108 stops counting down the second standby time. That is, if the standby time monitoring unit 108 receives an instruction to switch to the third shooting mode (S508-YES), it stops counting down the second standby time that is being measured.

[0164] In step S511, the drive control unit 107 controls the imaging unit 104 to switch to the third imaging mode based on the instruction to switch to the third imaging mode acquired by the control unit 106. In step S511, once the drive control unit 107 has completed the switch from the first imaging mode to the third imaging mode, in step S512, the standby time monitoring unit 108 starts counting down the third standby time. Here, the third standby time is the time from the completion of the switch from the second imaging mode to the third imaging mode until the first image error information (e.g., afterimage amount) or second image error information (e.g., shading amount) that may be included in the radiographic image acquired by imaging, and which has the characteristic of decaying over time, falls below a predetermined value. Alternatively, error information other than the afterimage amount or shading amount may be used as the third image error information that may be included in the radiographic image.

[0165] In step S513, the standby time monitoring unit 108 determines whether the first standby time and the third standby time have been completed. If the countdown for the first standby time and the third standby time has not been completed (S513-NO), the standby time monitoring unit 108 continues the countdown for the first standby time and the third standby time. If either the first standby time or the third standby time has been completed, the standby time monitoring unit 108 only needs to continue monitoring the countdown for the other standby time that has not been completed.

[0166] The standby time monitoring unit 108 maintains the shooting preparation state (shooting impossible state) until the countdown for the first standby time, the third standby time, and all standby times is completed (S513-NO). Once the first standby time and the third standby time are completed (S513-YES), in step S514, the drive control unit 107 performs transition control to enable shooting in the third shooting mode on the shooting unit 104. The drive control unit 107 enables shooting in the third shooting mode when the first standby time and the third standby time are completed.

[0167] On the other hand, if the determination in step S508 does not result in a new instruction to switch to a third shooting mode different from the second shooting mode (S508-NO), in step S515, the standby time monitoring unit 108 determines whether the first standby time and the second standby time have been completed. If the countdown for the first standby time and the second standby time has not been completed (S515-NO), the standby time monitoring unit 108 continues the countdown for the first standby time and the second standby time. Here, if either the first standby time or the second standby time has been completed, the standby time monitoring unit 108 only needs to continue monitoring the countdown for the other standby time that has not been completed.

[0168] The standby time monitoring unit 108 maintains the shooting preparation state (shooting impossible state) until the countdown for the first standby time, the second standby time, and all standby times is completed (S515-NO). Once the first standby time and the second standby time are completed (S515-YES), in step S516, the drive control unit 107 performs transition control to enable shooting for the second standby time on the shooting unit 104.

[0169] The control unit 106 may also perform display control to display the result of the countdown measurement by the standby time monitoring unit 108 on a display device (display unit) such as a display. In addition, the control unit 106 may notify the user that the countdown measurement by the standby time monitoring unit 108 has been completed by displaying it on a display device (display unit) not shown, or by generating a sound from a sound-generating device (sound-generating unit) such as a speaker.

[0170] According to this embodiment, even if multiple instructions to switch to different shooting modes are received, by performing shooting based on the completion of the waiting time in each shooting mode in which shooting is performed consecutively, it becomes possible to acquire images of excellent quality that can be used for diagnosis, etc., in the shortest possible time. For example, if an instruction to switch to a third shooting mode is received while waiting (preparing to shoot) to become ready to shoot in the second shooting mode, the countdown of the waiting time is reset based on the combination of shooting modes, and the switching operation can be performed without making the user wait unnecessarily.

[0171] According to each of the second to fourth embodiments described above, when taking multiple shots using different shooting modes, it becomes possible to acquire images with better image quality in the shortest possible time.

[0172] (Fifth Embodiment) Figure 17 shows an example configuration of a bone density measurement system 100 (hereinafter also referred to as a radiography system or radiography device) in the fifth embodiment. The bone density measurement system 100 comprises a radiation generator 10, a radiography device 30, an irradiation control device 31, an imaging console 32 (information processing unit), and a bone density calculation console 33 (bone information calculation unit). The irradiation control device 31, the imaging console 32, and the bone density calculation console 33 may be configured as a single information processing device 34. The information processing device 34 has a storage unit 35 (memory), which stores information acquired by the irradiation control device 31, the imaging console 32, and the bone density calculation console 33. The information stored in the storage unit 35 is shared among the irradiation control device 31, the imaging console 32, and the bone density calculation console 33 and can be used for various processes. The storage unit 35 may be provided inside the imaging console 32.

[0173] The radiation generator 10 is equipped with a radiation tube that generates radiation and irradiates a subject such as a patient 20 with radiation. The radiation generator 10 is equipped with an optical imaging device 12 that can acquire an optical image of the patient 20 (subject). The optical imaging device 12 can be composed of an optical camera or the like attached to the radiation generator 10. When the radiography device 30 is imaging, the optical imaging device 12 is attached to the radiation generator 10 so that the direction in which radiation is emitted from the radiation generator 10 coincides with the direction in which the optical imaging device 12 is imaging. The optical imaging device 12 is installed near the radiation tube of the radiation generator 10 so that it can image the direction in which radiation is emitted from the radiation generator 10. The optical imaging device 12 moves in conjunction with the movement of the radiation tube, and the imaging range of the optical imaging device 12 can include the radiation irradiation area.

[0174] The irradiation control device 31 has a circuit that mediates communication and monitors the status of the radiography apparatus 30 and the radiation generator 10. For example, the irradiation control device 31 controls the irradiation of radiation from the radiation generator 10 and controls the imaging of the patient 20 (subject) by the radiography apparatus 30. The irradiation control device 31 may also have a built-in HUB for connecting multiple network devices. When the exposure switch attached to the radiation generator 10 is operated, the irradiation control device 31 transmits a start request signal to the radiography apparatus 30. The start request signal may be a signal requesting the radiography apparatus 30 to prepare to accept radiation irradiation. In response to receiving the start request signal, the radiography apparatus 30 begins to prepare to accept radiation irradiation. When the radiography apparatus 30 is ready, it transmits a start-ready signal to the radiation generator 10 via the communication unit 190. The control unit 180 of the radiography apparatus 30 instructs the communication unit 190 to transmit the start-ready signal. Here, the start-ready signal may be a signal that notifies that it is possible to start radiation irradiation by the radiation generator 10. Upon receiving a start signal via the communication unit 190, the irradiation control device 31 instructs the radiation generator 10 to begin irradiating with radiation. After transmitting the start signal, the control unit 180 of the radiography apparatus 30 repeatedly performs a read operation using the read circuit 160. The signal processing unit 170 of the radiography apparatus 30 measures the radiation dose after each read operation and determines whether the cumulative value exceeds a threshold. When the cumulative dose reaches the threshold, the control unit 180 transmits an irradiation stop signal to the irradiation control device 31. The radiography apparatus 30 transmits the irradiation stop signal, and upon receiving the irradiation stop signal, the irradiation control device 31 instructs the radiation generator 10 to stop irradiating with radiation.

[0175] The imaging console 32 can acquire various image information by applying various image processing and information processing to the radiographic images acquired by the radiography device 30. The imaging console 32 also acquires camera images (optical images) of the patient 20 (subject) from the optical imaging device 12.

[0176] The bone density calculation console 33 can acquire various image information by applying various image processing and information processing to the radiographic images acquired from the radiography device 30 and the optical images acquired from the optical imaging device 12. By performing image processing and analysis on the radiographic images acquired by the radiography device 30, the bone density calculation console 33 can acquire the relative position and relative angle (rotation angle) of the patient 20 with respect to the table 11 on which the patient 20 is placed, as well as contour images and contour images of the bone density calibration phantom.

[0177] Furthermore, the bone density calculation console 33 performs bone density measurement by applying various image processing and information processing to the radiographic images acquired by the radiography device 30, thereby obtaining bone information (bone density) of the patient 20 (subject). For bone density measurement imaging, the patient 20 (subject) to be measured for bone density is placed on the table 11, and radiation is irradiated to the imaging area for bone density measurement for a predetermined time. The bone density calculation console 33 performs bone density measurement by analyzing the radiographic images acquired by the bone density measurement imaging using the DEXA method, thereby obtaining bone information (bone density) of the patient 20. The table 11 on which the patient 20 is placed is movable in the XYZ directions, making it possible to align various imaging areas of the patient 20 with respect to the radiation generator 10.

[0178] The radiography apparatus 30 generates radiographic images based on radiation emitted from the radiation generator 10. The radiography apparatus 30 is equipped with, for example, a flat panel detector (FPDe). The radiography apparatus 30 can be powered by a battery, and the radiography apparatus 30 and the irradiation control device 31 can communicate using either wireless LAN communication or Ethernet® communication. Figure 17 shows an example of Ethernet® communication configuration, in which the radiography apparatus 30 is connected to the irradiation control device 31 via Ethernet®. The irradiation control device 31, the imaging console 32, and the bone density calculation console 33 are also connected via Ethernet®, and the radiography apparatus 30, the irradiation control device 31, the imaging console 32, and the bone density calculation console 33 can communicate with each other. This allows the radiographic images acquired by the radiography apparatus 30 to be shared among the irradiation control device 31, the imaging console 32, and the bone density calculation console 33. Furthermore, the optical images captured by the optical imaging device 12 can be shared among the irradiation control device 31, the imaging console 32, and the bone density calculation console 33.

[0179] The radiation generator 10 and the imaging console 32 are connected by a serial communication cable. The imaging console 32 communicates with the radiation generator 10 to set radiation irradiation conditions (tube current (mA), tube voltage (kV), etc.) and obtains implementation information from the radiation generator 10 indicating the completion of radiation irradiation. Note that the communication method connecting the radiation generator 10 and the imaging console 32 is not limited to a serial communication cable; it may also be connected using Ethernet®.

[0180] The irradiation control device 31 and the radiation generator 10 are connected by a dedicated line and communicate irradiation request signals, irradiation permission signals, irradiation stop signals, etc. The irradiation control device 31 receives a radiation irradiation request from the radiation generator 10. When the imaging preparation is complete in the radiography device 30, a readiness complete signal is sent from the radiography device 30 to the irradiation control device 31. The irradiation control device 31 transmits an irradiation permission signal to the radiation generator 10 in synchronization with the timing of receiving the readiness complete signal from the radiography device 30. The irradiation control device 31 starts irradiation from the radiation generator 10 in response to the irradiation permission signal, and when the dose information acquired from the radiography device 30 reaches a predetermined cumulative dose, it transmits an irradiation stop signal to the radiation generator 10, stopping the irradiation of radiation by the radiation generator 10.

[0181] The radiography device 30 transmits the radiographic image generated by receiving radiation to the imaging console 32, and the transmitted radiographic image is displayed on an unillustrated display unit connected to the imaging console 32. After imaging, the radiographic image is transmitted from the imaging console 32 to the bone density calculation console 33, and the bone density calculation console 33 measures the bone density by analyzing the radiographic image acquired by imaging for bone density measurement using the DEXA method, and obtains the bone information (bone density) of the patient 20. Next, the principle for calculating bone density using the DEXA method will be explained.

[0182] Generally, when radiation passes through patient 20, the radiation is attenuated by the interaction between the radiation and patient 20. In the radiation image acquired by the FPD of the radiation imaging device 30, the radiation intensity integrated with respect to the depth direction of patient 20 (radiation irradiation direction: Z direction) is reflected as a pixel value. Therefore, the pixel value I in the radiation image after the radiation has passed through patient 20 is expressed by the following equation 4.

[0183]

[0184] Here, I Ｏ : Pixel value in radiographic image without patient, μ: Mass attenuation coefficient [cm] ２ / g], σ: areal density [g / cm ２ ]

[0185] The mass attenuation coefficient depends on the substance (atomic number of the substance) and the energy of the radiation, and therefore varies depending on two different radiation energies and the substance (e.g., bone and soft tissue). Note that since the energy depends on monochromatic energy, in cases of attenuation involving multiple energies, such as in a radiation spectrum, it does not strictly match equation 4 above.

[0186] When radiation images are taken for two different radiation energies (hereinafter referred to as low energy and high energy), the following equation 5 holds true.

[0187]

[0188] Each subscript represents: L: low energy, H: high energy, B: bone, S: soft tissue. R represents the energy attenuation rate (transmittance). The density of the substance to be determined in the bone density measurement system 100 of the fifth embodiment is bone density σ Ｂ Therefore, in the bone density calculation console 33, by solving the above simultaneous equations, the bone density σ Ｂ This can be calculated using the following six equations. As a typical method for solving nonlinear simultaneous equations, the bone density calculation console 33 can perform analysis using, for example, the Newton-Raphson method.

[0189]

[0190] Here, α is the subtraction coefficient, and K is the calibration coefficient, which is a coefficient determined based on the calibration process described later. The subtraction coefficient α is the mass attenuation coefficient μ of high-energy soft tissue. ＨＳ And the mass attenuation coefficient μ of low-energy soft tissues. ＬＳ This is the ratio to the mass attenuation coefficient μ of high-energy soft tissue. ＨＳ The mass attenuation coefficient μ of low-energy soft tissues ＬＳ This is the coefficient obtained by dividing by [a certain factor].

[0191] The difference in transmittance between bone and soft tissue to low-energy and high-energy radiation (R Ｈ -R ＬTo determine the mass attenuation coefficient μ of the soft tissue at high energy, it is first necessary to match the transmittance of the soft tissue at low energy to the transmittance of the soft tissue at high energy. ＨＳ And the mass attenuation coefficient μ of low-energy soft tissues. ＬＳ A subtraction coefficient α is used, which is the ratio of to . The difference in transmittance (R) obtained by matching the transmittance of the soft tissue portion at low energy to the transmittance of the soft tissue portion at high energy. Ｈ -αR Ｌ ) does not have the dimension of bone density, so the calibration information (calibration coefficient K) obtained in advance by calibration using the QC phantom described later is used as the difference in transmittance (R Ｈ -αR Ｌ Bone information (bone density) can be obtained by multiplying by ).

[0192] As mentioned above, bone density measurement requires calibration using a bone density calibration phantom (Quality Control phantom, hereinafter referred to as "QC phantom") whose bone density is known in advance. The QC phantom contains bone equivalent material of known density, and the bone density calculation console 33 calculates the calibration coefficient K in advance by calibration using the QC phantom, and then calibrates the output value obtained from the radiography device 30 with the calibration coefficient K to determine the bone density. An example of a QC phantom is the "table-type phantom T-1 (hereinafter sometimes referred to as T1 phantom)" described in "JIS Z 4930 Performance evaluation phantom for X-ray bone density measurement".

[0193] An example of calculating the calibration coefficient K using a T1 phantom is shown below. The T1 phantom contains three bone-equivalent materials with known densities, which are 0.7, 1.0, and 1.3 [g / cm³]. ２ Figure 18 shows the relationship between the difference in transmittance between bone and soft tissue and bone density values ​​for radiation at different energy levels (low energy, high energy). The difference in transmittance between bone and soft tissue for low energy and high energy radiation (R) was calculated based on the calculation principle of bone density using the DEXA method. Ｈ -αR ＬThe relationship between (R) and bone density is linearly approximated as shown in Figure 18 to calculate the calibration coefficient K. In the example in Figure 18, the difference in transmittance between bone and soft tissue for low-energy and high-energy radiation (R) Ｈ -αR Ｌ The horizontal axis (x-axis) shows the bone density value [g / cm³]. ２ The vertical axis (y-axis) shows the values. Plotting the three known densities in the T1 phantom and linearly approximating the three points, the linear approximation is obtained as y = 15.891 * x - 0.1. The calibration coefficient K obtained by the linear approximation is 15.891.

[0194] Figure 19 shows an example of the configuration of a radiography apparatus 30 in the fifth embodiment. The radiography apparatus 30 has a plurality of pixels arranged in the imaging area IR to form a plurality of rows and a plurality of columns, a plurality of drive lines 110, and a plurality of signal lines 120. The plurality of drive lines 110 are arranged corresponding to a plurality of rows of pixels, with each drive line 110 corresponding to any one pixel row. The plurality of signal lines 120 are arranged corresponding to a plurality of columns of pixels, with each signal line 120 corresponding to any one pixel column.

[0195] The multiple pixels include multiple imaging pixels 101 used to acquire a radiation image and one or more detection pixels 104 used to monitor the radiation dose.

[0196] Each imaging pixel 101 includes a conversion element 102 that converts radiation into an electrical signal, and a switch element 103 that connects the corresponding signal line 120 to the conversion element 102. Each detection pixel 104 includes a conversion element 105 that converts radiation into an electrical signal, and a switch element 106 that connects the corresponding signal line 120 to the conversion element 105. The detection pixels 104 are arranged to be included in rows and columns formed by a plurality of imaging pixels 101. In Figure 19, the imaging pixels 101 and detection pixels 104 are distinguished by applying different hatching to the conversion elements 102 and 105.

[0197] The conversion elements 102 and 105 may be composed of a scintillator that converts radiation into light and a photoelectric conversion element that converts light into an electrical signal. The scintillator is generally formed in a sheet shape to cover the imaging area IR and is shared by multiple pixels. Alternatively, the conversion elements 102 and 105 may be composed of conversion elements that directly convert radiation into an electrical signal.

[0198] Switch elements 103 and 106 may include thin-film transistors (TFTs) in which the active region is made of a semiconductor such as amorphous silicon or polycrystalline silicon.

[0199] The first electrode of the conversion element 102 is connected to the first main electrode of the switch element 103, and the second electrode of the conversion element 102 is connected to the bias line 130. One bias line 130 extends in the column direction and is commonly connected to the second electrodes of multiple conversion elements 102 arranged in the column direction. The bias line 130 receives a bias voltage Vs from the power supply circuit 140. The second main electrode of the switch element 103 of one or more imaging pixels 101 included in one column is connected to one signal line 120. The control electrode of the switch element 103 of one or more imaging pixels 101 included in one row is connected to one drive line 110.

[0200] The detection pixel 104 has the same pixel configuration as the imaging pixel 101 and is connected to the corresponding drive line 110 and the corresponding signal line 120. The imaging pixel 101 may also be connected to the same signal line 120 as the detection pixel 104.

[0201] The drive circuit 150 is configured to supply drive signals to the pixels to be driven through a plurality of drive lines 110 in accordance with control signals from the control unit 180. In the fifth embodiment, the drive signal is a signal to turn on the switch element included in the pixel to be driven. The switch element of each pixel is turned on by a high-level signal and turned off by a low-level signal. Therefore, this high-level signal is called the drive signal. When a drive signal is supplied to a pixel, the signal stored in the conversion element of that pixel becomes readable by the readout circuit 160. When a drive line 110 is connected to a detection pixel 104, that drive line 110 is called a detection drive line 111.

[0202] The readout circuit 160 is configured to read signals from multiple pixels through multiple signal lines 120. The readout circuit 160 includes multiple amplification units 161, a multiplexer 162, and an analog-to-digital converter (hereinafter referred to as an A / D converter (ADC)) 163. Each of the multiple signal lines 120 is connected to a corresponding amplification unit 161 among the multiple amplification units 161 of the readout circuit 160. One signal line 120 corresponds to one amplification unit 161. The multiplexer 162 selects the multiple amplification units 161 in a predetermined order and supplies the signals from the selected amplification units 161 to the A / D converter 163. The A / D converter 163 converts the supplied signals into digital signals and outputs them.

[0203] The signal read from the imaging pixel 101 is supplied to the signal processing unit 170, where it is processed through calculations, storage, and other operations. Specifically, the signal processing unit 170 includes a calculation unit 171 and a storage unit 172. The calculation unit 171 generates a radiation image based on the signal read from the imaging pixel 101 and supplies it to the control unit 180. The signal read from the detection pixel 104 is supplied to the signal processing unit 170, where it is processed through calculations, storage, and other operations. Specifically, the signal processing unit 170 outputs information indicating radiation irradiation to the radiation imaging device 30 based on the signal read from the detection pixel 104. For example, the signal processing unit 170 detects radiation irradiation to the radiation imaging device 30 and determines the radiation dose and / or integrated radiation dose.

[0204] The control unit 180 controls the drive circuit 150 and the readout circuit 160 based on information from the signal processing unit 170. The control unit 180 controls, for example, the start and end of exposure (accumulation of charge corresponding to the irradiated X-rays by the imaging pixel 101) based on information from the signal processing unit 170.

[0205] To determine the radiation dose, the control unit 180 controls the drive circuit 150 to scan only the detection drive line 111, making it possible to read only the signals from the detection pixels 104. Next, the control unit 180 controls the readout circuit 160 to read the signals from the column corresponding to the detection pixels 104 and output them as information indicating the radiation dose. Through this operation, the radiography apparatus 30 can obtain irradiation information for the detection pixels 104 while radiation is being irradiated.

[0206] The communication unit 190 is controlled by the control unit 180 and has the function of communicating between the radiography apparatus 30 and an external device (irradiation control device 31). The communication may be wired or wireless. The communication may conform to any standard. To accommodate multiple communication standards, the radiography apparatus 30 may be equipped with multiple communication units 190.

[0207] Figure 20 shows a detailed circuit configuration example of the amplification unit 161. The amplification unit 161 includes a differential amplifier circuit AMP and a sample-and-hold circuit SH. The differential amplifier circuit AMP amplifies the signal appearing on the signal line 120 and outputs it. The control unit 180 can reset the potential of the signal line 120 by supplying a control signal φR to the switch element of the differential amplifier circuit AMP. The output from the differential amplifier circuit AMP can be held by the sample-and-hold circuit SH. The control unit 180 causes the sample-and-hold circuit SH to hold the signal by supplying a control signal φSH to the switch element of the sample-and-hold circuit SH. The signal held by the sample-and-hold circuit SH is read out by the multiplexer 162.

[0208] Figure 21 is a diagram showing the imaging flow of DEXA imaging in the bone density measurement system 100 of the fifth embodiment. In the following description, the imaging console 32 will be described as the main processing unit for the processes S301 to S303, but this is not limited to this example, and the bone density calculation console 33 may also be the main processing unit. First, in order to calibrate the gain of each pixel in the multiple pixels arranged in the imaging area IR of the radiography device 30, in S301, two images (hereinafter referred to as 2-shot imaging) are taken under different radiation energy irradiation conditions without a QC phantom in the imaging area IR, and an image for calibrating the gain of each pixel is obtained (2-shot imaging without QC phantom). In the 2-shot imaging of S301, the imaging console 32 takes 2-shot images multiple times to remove noise and generates gain calibration images for each radiation energy irradiation condition. Before imaging the subject, the imaging console 32 performs multiple imaging scans under different radiation energy irradiation conditions without a bone density calibration phantom (QC phantom) in the imaging area IR, and acquires calibration images to calibrate the gain of each pixel in the imaging area IR. The imaging console 32 stores the position and orientation of the radiation tube, the radiation irradiation area, the position of the table, the position of the FPD, and the radiation irradiation conditions (tube voltage, tube current, irradiation time) as irradiation information 1A in the storage unit 35.

[0209] Next, in S302, with the QC phantom in the imaging IR region, two imaging sessions (2-shot imaging with QC phantom) are performed under different radiation energy irradiation conditions, and the imaging console 32 calculates the calibration coefficient K. In the 2-shot imaging in S302, the imaging console 32 performs 2-shot imaging multiple times to remove noise and calculates the calibration coefficient K. With the bone density calibration phantom (QC phantom) in the imaging IR region, the imaging console 32 performs multiple imaging sessions under different radiation energy irradiation conditions, and calculates calibration information (calibration coefficient K) using the image from which noise has been removed from the calibration image. S301 and S302 together are called QC imaging.

[0210] During the 2-shot imaging in S302, the optical imaging device 12 is used to capture an optical image including the table 11 and the QC phantom. The imaging console 32 also stores the position and orientation of the radiation tube, the radiation irradiation area, the position information of the table, the position of the FPD, and the radiation irradiation conditions (tube voltage, tube current, irradiation time) as irradiation information 2A in the storage unit 35.

[0211] Next, in S303, two images are taken of the patient 20 (subject) as a 2-shot imaging (DEXA imaging) with different radiation energy irradiation conditions. Since S301 and S302 are performed in the morning before the patient imaging order is received, they are performed as general imaging or separate imaging before S303. Therefore, the position and orientation of the radiation tube of the radiation generator 10, the position of the table, the position of the FPD, and the radiation irradiation area have moved during the imaging in S301 and S302, so it is necessary to set the position before S303 in order to perform DEXA imaging of the patient 20 (subject). This position setting can be done based on the alignment process which will be explained later using Figure 22.

[0212] In S304, the imaging console 32 uses the data generated in S301, S302, and S303, and the bone density calculation console 33 calculates the bone density of the patient 20 (subject).

[0213] If the position of the QC phantom during QC imaging and the position of the bone being measured in patient 20 (subject) during DEXA imaging are misaligned, it may be impossible to obtain accurate bone density values ​​due to the effects of radiation heeling. Therefore, it is desirable to align the positions of the QC phantom during QC imaging and the bone being measured during DEXA imaging as closely as possible. By performing a positioning process that aligns the position of the QC phantom during QC imaging with the bone being measured in patient (subject) during DEXA imaging, it becomes possible to calculate highly accurate bone density values.

[0214] Figure 22 illustrates the alignment process in the fifth embodiment, which aligns the QC phantom during QC imaging with the position of the bone to be measured in the subject during DEXA imaging (S303). The method of performing the alignment process within the DEXA imaging (S303) processing flow of Figure 21 will be explained using Figure 22. The radiographic image 410 in Figure 22 includes the radiographic image 411 of the QC phantom generated by the two-shot imaging with the QC phantom taken in S302 of Figure 21, and in the radiographic image 411, substances of different densities can be distinguished as differences in image density. Also in S302, the imaging console 32 generates an optical image 400 taken by the optical imaging device 12. The optical image 400 includes an image of the table 11 and the optical image 401 of the QC phantom, in which the QC phantom was captured.

[0215] The imaging console 32 generates a contour image 421 of the QC phantom, which is an image of the contour of the density boundary, by image processing of the radiation image 411 of the QC phantom. Here, the contour image 421 is positional information that indicates the shape of the QC phantom and the position of the boundaries of different density distributions. Positional information is, for example, information (contour image) that indicates the extent of a two-dimensional region that has transparency (e.g., semi-transparency) so that the position of the boundary can be seen when superimposed on an optical image. The imaging console 32 adjusts the size and position of the radiation image 411 and the optical image 401 of the QC phantom so that the contour image 421 and the optical image 401 of the QC phantom overlap. Then, the imaging console 32 generates a QC imaging image 420 as a superimposed image (first superimposed image) by superimposing (merging) the contour image 421 and the optical image 401 of the QC phantom (S302).

[0216] In the process of S303, when aligning the patient 20 (subject) for DEXA imaging, the imaging console 32 generates an optical image 430 of the subject captured by the optical imaging device 12. The optical image 430 of the subject includes the patient 20 (subject) on the table 11.

[0217] Using the position and orientation of the radiation tube, the radiation irradiation area, the table position information, and the FPD position stored in the memory unit 35 as irradiation information 2A, the imaging console 32 aligns the QC imaging image 420 with the optical image 430 of the subject and generates a superimposed image 440 (second superimposed image) by superimposing the outline image 421 of the QC phantom onto the optical image 430 of the subject (S303).

[0218] The imaging console 32 controls the display to show the superimposed image 440 on an unshown display unit of the imaging console 32, allowing the operator to confirm the discrepancy between the position corresponding to the bone portion of the phantom during QC imaging and the position of the bone portion of the patient 20 (subject) to be measured. If there is a positional discrepancy, the position and orientation of the patient 20 (subject), the table 11, the radiation tube of the radiation generator 10, and the radiation irradiation area are changed to eliminate the discrepancy. After this adjustment is made and combined with the irradiation conditions 2A stored in the memory unit 35, the bone density calculation console 33 irradiates the patient 20 (subject) with radiation from the radiation generator 10 and performs DEXA imaging (S303), and calculates the bone density of the patient 20 (subject) using the data generated in S301, S302, and S303 (S304). The bone density calculation console 33 acquires the bone density of the patient 20 (subject) using calibration information (calibration coefficient K) obtained using a bone density calibration phantom (QC phantom) aligned to the position of the contour image 421 in the superimposed image 440 (second superimposed image).

[0219] The imaging console 32 may determine the degree of positional misalignment between the position corresponding to the bone portion of the contour image 421 of the bone density calibration phantom and the position of the bone portion of the subject to be measured in the superimposed image 440 (second superimposed image). If the degree of misalignment is greater than a predetermined value, the imaging console 32 may display a notification on its display unit. Alternatively, if no positional misalignment is detected, the imaging console 32 may display a notification on its display unit indicating that no misalignment has occurred.

[0220] Furthermore, if the degree of misalignment is greater than a predetermined value as determined by the imaging console 32, the position of the table 11 on which the subject is placed may be moved to adjust the position of the table 11 so that the misalignment is correct. Alternatively, if the degree of misalignment is greater than a predetermined value as determined by the imaging console 32, the position or orientation of the radiation tube in the radiation generator 10 that emits radiation may be adjusted so that the misalignment is correct.

[0221] Next, we will explain the processing during follow-up observation. Figure 23 is a diagram showing the imaging flow for follow-up observation of DEXA imaging in the bone density measurement system of the fifth embodiment. 7A in Figure 23 shows the processing flow for past bone density measurements, and 7B in Figure 23 shows the processing flow for the current bone density measurement for the same subject. The processing from S501 to S504 in 7A of Figure 23 is the processing for past bone density measurements for the same patient (subject) for follow-up observation, and the content of the processing may be equivalent to the processing explained using Figures 21 and 22, or it may be equivalent to the processing from S511 to S514 which will be described later in the explanation of processing flow 7B. Note that the processing from S501 to S503 and S511 to S513 will be explained with the imaging console 32 as the main processing unit, but this is not limited to this example, and the bone density calculation console 33 may be the main processing unit.

[0222] Processing flow 7B shows the imaging flow for the examination during follow-up. First, in order to calibrate the gain of each pixel in the multiple pixels arranged in the imaging area IR of the radiography device 30, in S511, two images (hereinafter referred to as 2-shot imaging) are taken under different radiation energy irradiation conditions without a QC phantom in the imaging area IR, and an image for calibrating the gain of each pixel is obtained (2-shot imaging without QC phantom). At this time, the imaging console 32 may display the irradiation information 1A from S501, which was stored during the previous examination, on the display unit of the imaging console 32 to assist in setting the imaging conditions to the same as those of S501 (S301). Alternatively, the imaging console 32 may use the irradiation information 1A to move the position and orientation of the radiation tube, the radiation irradiation area, the position of the table 11, and the position of the FPD to align them to the same position as the 2-shot imaging position of S501.

[0223] In the 2-shot imaging of S511, the imaging console 32 performs 2-shot imaging multiple times to remove noise and generates gain calibration images for the irradiation conditions of each radiation energy. The imaging console 32 stores the position and orientation of the radiation tube, the radiation irradiation area, the position of the table, the position of the FPD, and the radiation irradiation conditions (tube voltage, tube current, irradiation time) as irradiation information 1B in the storage unit 35.

[0224] Next, in S512, with the QC phantom present in the imaging region IR, two imaging sessions (2-shot imaging with QC phantom) are performed under different radiation energy irradiation conditions, and the imaging console 32 calculates the calibration coefficient K. In the 2-shot imaging in S512, the imaging console 32 performs 2-shot imaging multiple times to remove noise and calculates the calibration coefficient K. S511 and S512 together are called QC imaging. During the 2-shot imaging with QC phantom in S512, an optical image including the table 11 and the QC phantom is captured using the optical imaging device 12.

[0225] At this time, the imaging console 32 may display the irradiation information 2A from S502, which was stored during the previous examination, on its display unit to assist in setting the imaging conditions to be the same as those of S502 (S302). Alternatively, the imaging console 32 may use the irradiation information 2A to adjust the position and orientation of the radiation tube, the radiation irradiation area, the table position, and the FPD position.

[0226] Furthermore, the imaging console 32 may display an image on its display unit that superimposes the optical image 400 captured in S502 during the previous inspection onto the image data (optical image) captured by the optical imaging device 12 in S512, thereby assisting in the alignment operation. The imaging console 32 also stores the position and orientation of the radiation tube, the radiation irradiation area, the position information of the table, the position of the FPD, and the radiation irradiation conditions (tube voltage, tube current, irradiation time) as irradiation information 2B in the storage unit 35.

[0227] Next, in S513, two images are taken of the patient 20 (subject) as a 2-shot imaging (DEXA imaging) with different radiation energy irradiation conditions. Since S511 and S512 are performed in the morning before the patient imaging order is received, they are performed as general imaging or separate imaging before S513. Therefore, the position and orientation of the radiation tube of the radiation generator 10, the radiation irradiation area, the position of the table, and the position of the FPD have moved during the imaging in S511 and S512, so it is necessary to set the position before S513 in order to perform DEXA imaging of the patient 20 (subject). This position setting can be done based on the alignment process explained earlier using Figure 22.

[0228] Furthermore, for follow-up observation, it is necessary to match the posture and position of the patient 20 (subject) between the previous imaging session (past imaging session) and the current imaging session (present). Figure 24 is a diagram illustrating the process of matching the position and posture of the subject for follow-up observation.

[0229] In the processing of S513, the imaging console 32 generates a contour image 600 that shows the contour of the subject and the contour of the QC phantom by performing image processing on the superimposed image 440 (second superimposed image) acquired in the processing of S503 in a previous bone density measurement examination. The contour image 600 includes a contour image 601 of the QC phantom, a contour image 602 of the patient 20 (subject), and a contour image 603 of the table 11. Here, the contour image 601 of the QC phantom is positional information that shows the shape of the QC phantom and the position of the boundary of different density distributions. Positional information is, for example, information (contour image) that shows the extent of a two-dimensional region that has transparency (e.g., semi-transparency) so that the position of the boundary can be seen when superimposed with an optical image. Furthermore, the contour image 602 of patient 20 (subject) and the contour image 603 of table 11 are positional information indicating the location of the boundaries of their respective shapes. Positional information is, for example, information (contour image) that shows the extent of a two-dimensional region that has transparency (e.g., semi-transparency) so that the location of the boundary can be seen when superimposed on an optical image.

[0230] Alternatively, the imaging console 32 may perform image processing using the optical image 610 of the patient 20 (subject) and the information of the optical image (for example, the optical image 400 in Figure 22) that includes the table 11 and the QC phantom acquired in processing S511 and S512, thereby generating a contour image 600 that includes the contour image 602 of the patient 20 (subject) and the contour image 601 of the QC phantom. The imaging console 32 uses the position and orientation of the radiation tube and the position information of the table stored in the storage unit 35 as irradiation information 2A to align the positions of the contour image 601 of the QC phantom and the contour image 602 of the patient 20 (subject), and generates a contour image 600 by superimposing the contour image 601 of the QC phantom onto the contour image 602 of the subject. The contour image 600 may be generated by any of the above methods.

[0231] Furthermore, the imaging console 32 acquires an optical image 610 of the patient 20 (subject) captured using the optical imaging device 12. The optical image 610 of the patient 20 (subject) is an image that includes the patient 20 (subject) on the table 11.

[0232] The imaging console 32 generates a superimposed image 620 (third superimposed image) using the stored radiation tube position and orientation, radiation irradiation area, table position information, and FPD position stored in the memory unit 35 as irradiation information 2B. That is, the imaging console 32 uses the radiation tube position and orientation, radiation irradiation area, table position information, and FPD position to align the position of the contour image 600 with the optical image 610 of the patient 20 (subject), and generates a superimposed image 620 (third superimposed image) by superimposing the contour image 600 onto the optical image 610 of the patient 20 (subject). This makes it possible to match the posture and position of the patient 20 (subject) at the time of the previous imaging (past imaging) and the current imaging (present) for follow-up observation. Here, the imaging console 32 may be controlled to adjust the position of the table 11 in order to match the posture and position of the patient 20 (subject) during the previous imaging session (past imaging session) with that of the current imaging session (present imaging session), or it may be controlled to adjust the position and orientation of the radiation tube in the radiation generator 10.

[0233] Since bone density values ​​change depending on the orientation and angle of the bone, it is desirable to keep the bone orientation and angle as similar as possible to the previous image when performing follow-up examinations. The position and orientation of the bone are affected by the posture of the subject outside the area being irradiated with radiation, but by using superimposed image 620 (third superimposed image), the posture of the subject outside the area being irradiated with radiation can be matched to the posture of the subject at the time of the previous bone density measurement, allowing for a highly accurate understanding of changes in bone density during follow-up examinations.

[0234] In S514, the bone density calculation console 33 uses the data generated in S511, S512, and S513 by the imaging console 32 to calculate the bone density of the patient 20 (subject).

[0235] According to the configuration of the fifth embodiment described above, it becomes possible to acquire bone density accurately and stably. By appropriately aligning the calibration position with the patient's position during imaging for bone density measurement, it becomes possible to acquire the correct bone density value accurately and stably.

[0236] [Other Embodiments] The present invention can also be realized by supplying a program that implements one or more of the functions of the above embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (for example, an ASIC) that implements one or more functions.

[0237] The technical ideas derived from this disclosure are not limited to the exemplary embodiments disclosed, but are intended to encompass various modifications of the exemplary embodiments, or substitutions with equivalent structures or functions. The scope of the following claims should be interpreted in the broadest way to encompass all such modifications and equivalent structures and functions.

[0238] This application claims priority based on Japanese Patent Application No. 2025-158538 filed on September 24, 2025, Japanese Patent Application No. 2025-037708 filed on March 10, 2025, Japanese Patent Application No. 2025-031938 filed on February 28, 2025, and Japanese Patent Application No. 2025-010637 filed on January 24, 2025, and all of the contents of those applications are incorporated herein by reference.

[0239] 100: Radiography device 180: Control unit 190: Communication unit 500: Radiography system 502: Information processing unit 505: Synchronization control unit 506: Radiation generator 510: Bone information calculation device

Claims

1. A radiography system for acquiring bone information based on a first radiography image and a second radiographic image obtained by predetermined radiography, characterized in that it has a processing means for causing a notification unit to issue a warning regarding bone information based on the radiation exposure time of the predetermined radiography.

2. The radiography system comprises a radiography apparatus capable of performing a first imaging for bone information calculation and a second imaging different from the first imaging for bone information calculation, wherein the processing means acquires, in the first imaging, a first radiographic image generated by irradiating the radiography apparatus with radiation of a first energy and a second radiographic image generated by irradiating it with radiation of a second energy different from the first energy, determines whether the radiation irradiation is insufficient based on a comparison of the radiation irradiation time to the radiography apparatus with the permitted time of the permitted radiation irradiation standard, displays a warning display in the notification unit if the radiation irradiation is insufficient based on the comparison, and calculates bone information of the subject using the first radiographic image and the second radiographic image, as described in claim 1.

3. The radiography system comprises a radiography device capable of performing a first imaging for bone information calculation and a second imaging different from the first imaging for bone information calculation, wherein the processing means determines whether the radiation exposure is insufficient based on a comparison of the radiation exposure time to the radiography device with the permitted time of the permitted standard for radiation exposure, and, based on the comparison, causes the notification unit to display a warning display if the radiation exposure is insufficient, as described in claim 1.

4. The radiography system according to claim 2, characterized in that the bone information of the subject includes at least one of bone mineral density and bone density.

5. The radiation imaging system according to claim 2 or 3, characterized in that the processing means determines whether the radiation irradiation is insufficient when performing the first imaging.

6. The radiography system according to claim 2 or 3, further comprising synchronization control means for synchronizing the timing of irradiating with radiation from a radiation generator with the timing of performing the first or second imaging with the radiography device.

7. The radiography system according to claim 6, characterized in that the synchronization control means transmits a signal to the radiation generator to activate the irradiation permission signal, thereby causing the radiation generator to irradiate, and transmits a signal to deactivate the irradiation permission signal, thereby stopping the irradiation of the radiation.

8. The radiation imaging system according to claim 7, characterized in that the radiation irradiation time is the time from activation of the irradiation permission signal to deactivation of the irradiation permission signal.

9. The radiography system according to claim 7, characterized in that the radiation generator transmits a request signal to activate irradiation permission to the radiography device via the synchronization control means based on the user's irradiation start operation, the radiography device transmits an irradiation permission signal to the synchronization control means after a preparation operation, and the synchronization control means transmits a signal to the radiation generator to activate the irradiation permission signal based on the receipt of the irradiation permission signal.

10. The radiography system according to claim 7, characterized in that the synchronization control means transmits a signal to the radiation generator to invalidate the irradiation permission signal based on a signal transmitted from the radiation generator when the user performs an irradiation stop operation while the radiation is being irradiated.

11. The radiation imaging system according to claim 2 or 3, characterized in that the processing means causes the notification unit to display a warning display different from the warning display when the radiation is not irradiated.

12. The radiography system according to claim 2, characterized in that the processing means displays the first radiographic image and the second radiographic image acquired by the first radiography on the notification unit.

13. The radiation imaging system according to claim 12, characterized in that the processing means causes the radiation irradiation information of the radiation irradiated from the radiation generator to be displayed on the notification unit.

14. The radiography system according to claim 2 or 3, characterized in that the processing means determines whether the radiation irradiation to the radiography device is insufficient based on a comparison of the irradiation information of the radiation irradiated from the radiation generator with the previously acquired standard irradiation information.

15. The radiation imaging system according to claim 13, characterized in that the irradiation information includes at least one of the following: the tube voltage when irradiating with radiation, the radiation irradiation time, the tube current when irradiating with radiation, and the integrated value (mAs) of the tube current and the radiation irradiation time.

16. The radiography system according to claim 2, characterized in that the processing means determines whether the radiation irradiation to the radiography device is insufficient based on a comparison between the pixel values ​​of the subject's tissue acquired based on the first radiographic image and the second radiographic image and a reference pixel value acquired in advance in the bone information calibration process.

17. The radiography system according to claim 16, characterized in that the tissue of the subject includes bone or soft tissue excluding the bone.

18. The radiography system according to claim 2, characterized in that the number of first and second radiographic images acquired in the first imaging is different from the number of radiographic images acquired in the second imaging.

19. A radiography system comprising control means capable of performing a first radiography, in which one imaging is performed based on a single irradiation permission, and a second radiography, in which two imagings are performed based on a single irradiation permission, wherein the control means is characterized in that the second radiography is acquired based on the two imagings and bone information is acquired based on the two radiographic images.

20. A radiography method for a radiography system that acquires bone information based on a first radiography image and a second radiographic image obtained by predetermined radiography, characterized by comprising a processing step of causing a notification unit to notify a warning regarding bone information based on the radiation irradiation time of the predetermined radiography.

21. An information processing device for processing information acquired from a radiography apparatus capable of performing a first imaging for bone information calculation and a second imaging different from the first imaging for bone information calculation, comprising a processing means for determining whether radiation irradiation is insufficient based on a comparison of the radiation irradiation time to the radiography apparatus with the permitted time of the permitted standard for radiation irradiation, wherein the processing means causes a warning display to be shown on a notification unit when the radiation irradiation is insufficient based on the comparison.

22. An information processing method for an information processing device that processes information acquired from a radiography apparatus capable of performing a first imaging for bone information calculation and a second imaging different from the first imaging for bone information calculation, comprising: a determination step of determining whether radiation irradiation is insufficient based on a comparison of the radiation irradiation time to the radiography apparatus with the permitted time of the permitted standard for radiation irradiation; and a notification step of causing a warning display to be shown in the notification unit if the radiation irradiation is insufficient based on the comparison.

23. A program that causes a computer to perform the radiography method described in claim 20.

24. A program that causes a computer to execute the information processing method described in claim 22.

25. A radiography apparatus comprising: a monitoring unit that monitors whether a first waiting time, which is measured when shooting in the first shooting mode, and a second waiting time, which is measured when switching from the first shooting mode to the second shooting mode, have been completed; and a control unit that, when the first waiting time and the second waiting time have been completed, enables shooting in the second shooting mode.

26. A shooting control device comprising: a monitoring unit that monitors whether a first waiting time, which is measured when shooting in the first shooting mode, and a second waiting time, which is measured when switching from the first shooting mode to the second shooting mode, have been completed; and a control unit that, when the first waiting time and the second waiting time have been completed, enables shooting in the second shooting mode.

27. A shooting control method characterized by comprising: a monitoring step of monitoring whether a first waiting time, which is measured by shooting in the first shooting mode, and a second waiting time, which is measured when switching from the first shooting mode to the second shooting mode, have been completed; and a control step of enabling shooting in the second shooting mode when the first waiting time and the second waiting time have been completed.

28. An information processing apparatus comprising: means for generating a first superimposed image by superimposing position information of a bone density calibration phantom, which is generated by image processing of a radiation image of a bone density calibration phantom with known bone density obtained by irradiation with radiation, onto an optical image of the bone density calibration phantom; means for aligning the positions of the first superimposed image and the optical image of a subject using the radiation irradiation information, and generating a second superimposed image by superimposing the position information onto the optical image of the subject; and acquisition means for acquiring the bone density of a subject using calibration information obtained using the bone density calibration phantom aligned to the position of the position information in the second superimposed image.

29. An information processing apparatus characterized by comprising: means for generating position information including the position information of the subject and the position information of the bone density calibration phantom by image processing of an image obtained in a past bone density measurement examination in which a bone density calibration phantom with a known bone density and the subject are superimposed; means for generating a superimposed image by aligning the position of the generated position information with the optical image of the subject using radiation irradiation information from the past bone density measurement and superimposing the position information onto the optical image of the subject; and acquisition means for acquiring the bone density of the subject using calibration information obtained using the bone density calibration phantom aligned with the position information of the bone density calibration phantom in the superimposed image.

30. An information processing method characterized by comprising: a step of generating a first superimposed image by superimposing position information of a bone density calibration phantom, which is generated by image processing of a radiation image of a bone density calibration phantom whose bone density is known and obtained by irradiation with radiation, onto an optical image of the bone density calibration phantom; a step of aligning the positions of the first superimposed image and the optical image of a subject using the radiation irradiation information, and generating a second superimposed image by superimposing the position information onto the optical image of the subject; and a step of obtaining the bone density of a subject using calibration information obtained using the bone density calibration phantom, which has been aligned to the position of the position information in the second superimposed image.

31. An information processing method characterized by comprising: a step of generating positional information including the positional information of the subject and the positional information of the bone density calibration phantom by image processing of an image obtained in a past bone density measurement examination in which a bone density calibration phantom with a known bone density is superimposed on the subject; a step of aligning the positional information with the optical image of the subject using radiation irradiation information from the past bone density measurement, and generating a superimposed image by superimposing the positional information onto the optical image of the subject; and a step of obtaining the bone density of the subject using calibration information obtained using the bone density calibration phantom aligned to the positional information of the bone density calibration phantom in the superimposed image.

Images