Patent Description:
There is known a radiation imaging apparatus used in medical image diagnosis or other purposes with radiation such as X-rays that includes a sensor array, a two-dimensional array of pixels each with a combination of a switch such as a thin-film transistor (TFT) and a conversion element such as a photoelectric conversion element. Image data acquired in the radiation imaging apparatus is transferred to a control apparatus of the radiation imaging apparatus or an external apparatus such as an image processing apparatus, via a communications unit used in optical fiber communication using optical modules, wired communication such as Ethernet®, or wireless communication. For example, in medical image diagnosis, such a radiation imaging apparatus is used in acquiring digital radiation images through still-image capturing such as general imaging, or moving-image capturing such as fluoroscopic or continuous imaging.

Such a radiation imaging apparatus operates in a plurality of imaging modes suitable for purposes and usages of imaging, and switches those modes for various purposes. For example, a radiation imaging apparatus called a fluoroscopic apparatus can operate in two different imaging modes: a first imaging mode used to perform imaging operation called fluoroscopy to observe movements of an imaging target, and a second imaging mode to perform imaging operation called imaging to record an imaging target in diagnosis. The first imaging mode uses a fluoroscopy switch in performing fluoroscopy imaging operation, and the second imaging mode uses an imaging switch in performing recording imaging operation. For example, the first imaging mode provides high framerates and gain with low radiation doses in performing fluoroscopy imaging operation. The second imaging mode provides low framerates and gain with high radiation doses in performing diagnosis or recording imaging operation to carry out moving-image capturing with low speed or still-image capturing to capture individual images.

Such a radiation imaging apparatus repeats standby driving to reduce the dark current component likely to accumulate in pixels until the next capturing is started, during a standby period up to the next imaging, as discussed in <CIT>. Meanwhile, as discussed in <CIT>, a radiation imaging apparatus to perform imaging in a plurality of imaging modes can suffer an artifact that occurs in an image acquired in an imaging mode switched from another mode. To counteract the issue, the radiation imaging apparatus performs switching control to reduce the artifact in a changed imaging mode. The switching control is performable with the sensor array driven the same way as that before the change. <CIT> describes an imaging operation wherein first imaging on an irradiation field is changed to second imaging on a wider irradiation field and conversion elements are initialized in a period between the first and second imaging.

An embodiment of the disclosure takes into account switching control performed during a standby period in a radiation imaging apparatus to perform imaging in a plurality of imaging modes.

An embodiment of the disclosure is directed to a radiation imaging apparatus to perform imaging in a plurality of imaging modes that can perform control switching to an imaging mode suitable for use on a fluoroscopic apparatus during a standby period.

According to an aspect of the disclosure, there is provided a radiation imaging apparatus as specified in claims <NUM> to <NUM>. According to a second aspect of the disclosure, there is provided a radiation imaging system as specified in claims <NUM> to <NUM>. According to a third aspect of the disclosure, there is provided a method of controlling a radiation imaging apparatus as specified in claim <NUM>. According to a fourth aspect of the disclosure, there is provided a program as specified in claim <NUM>.

Further features of the disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

Some exemplary embodiments of the disclosure will be described below with reference to the attached drawings. The term "radiation" includes alpha rays, beta rays, gamma rays, particle rays, and cosmic rays, in addition to X-rays. Further, the following exemplary embodiments can be combined as appropriate, and a mode with a combination of exemplary embodiments as appropriate is also included as an exemplary embodiment of the disclosure.

In the exemplary embodiments of the disclosure, a radiation imaging apparatus offers a solution to an issue related to switching control in a standby period. For example, standby driven the same way as that in the imaging operation immediately before the standby period is unlikely to cause an artifact in an image in the next imaging that is performed through no change, allowing an image to be acquired in a short period after a press of the imaging switch. However, imaging modes are often switched in realty. For example, the radiation imaging apparatus used as a fluoroscopic apparatus uses a fluoroscopy imaging mode to observe an imaging target and switches to a recording imaging mode to perform still-image capturing. In other words, it should be taken into consideration what type of sensor-array driving control to be performed up to the next imaging in a different imaging mode from the preceding one during in a standby period, and the disclosure provides novel standby driving in a radiation imaging apparatus to perform imaging in a plurality of imaging modes.

<FIG> is a diagram illustrating a schematic configuration example of a radiation imaging system <NUM> according to a first exemplary embodiment of the disclosure. The radiation imaging system <NUM> includes a radiation imaging apparatus <NUM>, a radiation source <NUM>, a radiation source control apparatus <NUM>, a wireless access point (AP) <NUM>, a relay apparatus <NUM>, and a system control apparatus <NUM>, as illustrated in <FIG>. The AP <NUM> can be integral with the relay apparatus <NUM>, or can be excluded without using wireless communication. Further, although not illustrated, the radiation imaging system <NUM> can be connected to a radiology information system (RIS), a picture achieving and communication system (PACS), a printer, and other devices. In the following description, the term "unit" may refer to a circuit, a device, a hardware component, or a functionality, a functional module, a function, a subprogram, or similar components that are implemented by a processor executing a program stored in a memory device.

The radiation imaging apparatus <NUM> can communicate with the relay apparatus <NUM> as an external apparatus. Specifically, the radiation imaging apparatus <NUM> can communicate over a wired path with the relay apparatus <NUM> as an external apparatus. The radiation imaging apparatus <NUM> includes a housing provided with an external connection terminal (not illustrated) connecting to a connection terminal <NUM> of a wire cable. Further, the radiation imaging apparatus <NUM> can wirelessly communicate with the relay apparatus <NUM> as an external apparatus via the AP <NUM>. The radiation imaging apparatus <NUM> includes a radiation imaging unit <NUM>, an imaging control unit <NUM>, a storage unit <NUM>, a wireless communication unit <NUM>, a wired communication unit <NUM>, a power supply control unit <NUM>, a battery <NUM>, a setting unit <NUM>, an image processing unit <NUM>, and a selection unit <NUM>, as illustrated in <FIG>. The wireless communication unit <NUM> may be excluded with wired communication alone, and the battery <NUM> may be excluded with power supplied from the outside.

The radiation imaging unit <NUM> detects radiation <NUM> (including radiation passing through an object <NUM>) emitted from the radiation source <NUM>, and acquires image data to be a radiation image of the object <NUM>. In this process, the radiation imaging unit <NUM> can acquire image data of a still image and a moving image as the image data. Further, it is suitable to use a flat panel detector as the radiation imaging unit <NUM>, for example.

The imaging control unit <NUM> performs various controls related to radiation imaging performed by the radiation imaging apparatus <NUM>. The imaging control unit <NUM> controls driving of the radiation imaging unit <NUM>, imaging in acquiring radiation image data from the radiation imaging unit <NUM>, storage of the acquired image data, and transfer of the acquired image data to an external apparatus. Further, the imaging control unit <NUM> controls storage of image data in the storage unit <NUM>, transfer of image data to the relay apparatus <NUM> via the wireless communication unit <NUM> and the wired communication unit <NUM>. Furthermore, the imaging control unit <NUM> controls setting of driving timing and driving conditions for the radiation imaging unit <NUM>. In other words, the imaging control unit <NUM> can control imaging performed by the radiation imaging unit <NUM> by controlling driving of the radiation imaging unit <NUM> based on the various setting values.

The relay apparatus <NUM> and/or the system control apparatus <NUM> to be described below can include some or all of the functions of the image processing unit <NUM> of the radiation imaging apparatus <NUM>, depending on the system configuration.

The storage unit <NUM> stores programs for controlling operation of the radiation imaging apparatus <NUM>, and various kinds of information and various data for such control. Further, the storage unit <NUM> stores various kinds of information and various data such as that obtained by processing performed by the imaging control unit <NUM>. For example, the storage unit <NUM> stores image data obtained by the imaging control unit <NUM> and image data after correction, based on the control by the imaging control unit <NUM>.

The wireless communication unit <NUM> performs wireless communication with the relay apparatus <NUM> via the AP <NUM> in, for example, a wireless local area network (LAN). The wired communication unit <NUM> performs wired communication with the relay apparatus <NUM> through wiring (cables). The imaging control unit <NUM> performs such communications as command communication, radiation synchronization control communication, and image data communication with the relay apparatus <NUM>, using either one or both the wireless communication unit <NUM> or/and the wired communication unit <NUM>. For example, wired communication with Ethernet® can be performed as wired communication between the radiation imaging apparatus <NUM> and the relay apparatus <NUM>. Instead of wireless communication between the radiation imaging apparatus <NUM> and the relay apparatus <NUM> via the AP <NUM> is illustrated in <FIG>, direct wireless communication between them may be performed with the radiation imaging apparatus <NUM> or the relay apparatus <NUM> serving as an access point. Further, a communication technique such as wireless fidelity (Wi-Fi) or Bluetooth® can be used in wireless communication. Wireless communication between the radiation imaging apparatus <NUM> and the system control apparatus <NUM> is established with them set beforehand as connection destinations to each other.

The power supply control unit <NUM> controls a power source for supplying power to each of the components of the radiation imaging apparatus <NUM>, such as the radiation imaging unit <NUM> and the imaging control unit <NUM>, based on the control by the imaging control unit <NUM>.

The battery <NUM> is a power source in the radiation imaging apparatus <NUM>. In wired communication, for example, the power supply control unit <NUM> supplies power to each of the components of the radiation imaging apparatus <NUM> using a power source <NUM> of the relay apparatus <NUM> as an external apparatus to cause each of these components to operate. With wired communication disconnected, the power supply control unit <NUM> supplies power to each of the components of the radiation imaging apparatus <NUM> using the battery <NUM> in the radiation imaging apparatus <NUM> to cause each of these components to operate. In the present exemplary embodiment, the battery <NUM> is disposed in the radiation imaging apparatus <NUM>, but may be configured as a battery detachable from the radiation imaging apparatus <NUM>. Further, the battery <NUM> of the present exemplary embodiment is a device that can be charged by power supplied from the outside. A secondary battery such as a lithium ion battery or a nickel metal hydride battery, or an electric storage device such as a lithium ion capacitor or an electric double layer capacitor can also be used for the battery <NUM>.

The radiation source <NUM> is a device to generate the radiation <NUM> such as X-rays. The radiation source <NUM> includes an electron gun and a rotor. In this case, electrons accelerated by a high voltage generated by the radiation source control apparatus <NUM> collide with the rotor to generate the radiation <NUM>.

The system control apparatus <NUM> is an apparatus to generally control operation of the radiation imaging system <NUM>. The system control apparatus <NUM> performs various controls such as operation of the radiation imaging system <NUM>, and acquisition, input, and setting of imaging protocols, and data processing on radiation images captured by the radiation imaging apparatus <NUM>. The system control apparatus <NUM> has the application functionality of operating on a computer. In other words, the system control apparatus <NUM> includes at least one processor and at least one memory, and the processor runs programs stored in the memory to work each of function units that will be described below. Alternatively, some or all of the function units may be worked by dedicated hardware. For example, any of various computers and workstations can be suitably used for the system control apparatus <NUM>. The system control apparatus <NUM> is connected to a display device <NUM>, such as a display, to display menu information about controls and radiation images after imaging, and an input device <NUM>, such as a mouse and a keyboard, to perform various inputs. The system control apparatus <NUM> outputs images to the display device <NUM> and provides a graphical user interface using the display device <NUM>, while controlling the operation of the radiation imaging apparatus <NUM>. The above example is in which the system control apparatus <NUM>, the display device <NUM>, and the input device <NUM> are separate from one another, but a portable information terminal such as a laptop personal computer (PC) or a tablet may be used.

The relay apparatus <NUM> functions as an interface apparatus connected to the radiation imaging apparatus <NUM>, the system control apparatus <NUM>, and the radiation source control apparatus <NUM>. The relay apparatus <NUM> is connected to the system control apparatus <NUM> with Ethernet® or the like, and also functions as a relay apparatus in transferring image data acquired by the radiation imaging apparatus <NUM> to the system control apparatus <NUM>. The relay apparatus <NUM> includes a wired communication unit <NUM> to perform wired communication with the radiation imaging apparatus <NUM>, the power source <NUM> to supply power to the radiation imaging apparatus <NUM>, and an irradiation pulse generation unit <NUM> to issue an irradiation request to the radiation source control apparatus <NUM>. The relay apparatus <NUM> performs synchronous communication with the radiation imaging apparatus <NUM> and the radiation source control apparatus <NUM> to perform notification of information about an imaging request switch and perform control to synchronize the image acquisition timing and the radiation irradiation timing of the radiation source control apparatus <NUM>.

The radiation source control apparatus <NUM> controls the radiation <NUM> generated from the radiation source <NUM>. The radiation source control apparatus <NUM>, for example, is connected to switches for requesting radiation irradiation, such as an imaging switch <NUM> and a fluoroscopy switch <NUM>, and, in some cases, to an operation unit for setting irradiation conditions for radiation. For example, in performing imaging for recording or diagnosis, such as still-image capturing for capturing a radiation image in one frame, pressing the imaging switch <NUM> starts irradiation with radiation under irradiation conditions based on settings corresponding to the imaging switch <NUM>. Here, the imaging switch <NUM> corresponds to a third switch in some embodiments of the disclosure. In addition, pressing the fluoroscopy switch <NUM> starts irradiation with radiation under irradiation conditions based on settings corresponding to the fluoroscopy switch <NUM>. Further, the radiation source control apparatus <NUM> can switch between pulse fluoroscopy and continuous fluoroscopy. Here, the pulse fluoroscopy is moving-image capturing for capturing a radiation image in a plurality of frames through repetition of discretely pulsed irradiation in synchronization with the radiation imaging apparatus <NUM>. The continuous fluoroscopy is moving-image capturing for capturing a radiation image in a plurality of frames through continuous emission of a fixed amount of radiation.

In this case, the radiation source control apparatus <NUM> includes a selection switch <NUM> for selecting either the pulse fluoroscopy or the continuous fluoroscopy in response to a press of the fluoroscopy switch <NUM>. The functionality of the fluoroscopy switch <NUM> and the selection switch <NUM> corresponds to that of a first switch and a second switch in some embodiments of the disclosure. The imaging switch <NUM>, the fluoroscopy switch <NUM>, and the selection switch <NUM> each may not be a dedicated switch, and may be buttons on a user interface provided on the radiation source control apparatus <NUM> by way of example. The radiation source control apparatus <NUM> to perform continuous fluoroscopy or pulse fluoroscopy may not include the selection switch <NUM>. Further, the imaging switch <NUM> may be a switch that is operated in two phases: a preparation switch for pre-notifying the radiation imaging apparatus <NUM> and the radiation source control apparatus <NUM> of preparation for imaging, and a request switch for requesting actual imaging.

Next, an internal configuration of the radiation imaging unit <NUM> illustrated in <FIG> will be described with reference to <FIG> is a diagram illustrating an internal configuration example of the radiation imaging unit <NUM> illustrated in <FIG>. The radiation imaging unit <NUM> includes a drive circuit <NUM>, a sensor array <NUM>, an amplification circuit 203a, a sample-and-hold circuit 203b, a multiplexer <NUM>, an amplifier <NUM>, and an analog-to-digital (A/D) converter <NUM>, as illustrated in <FIG>. Here, the amplification circuit 203a, the sample-and-hold circuit 203b, the multiplexer <NUM>, the amplifier <NUM>, and the A/D converter <NUM> are included in a readout circuit <NUM>. That configuration allows the radiation imaging unit <NUM> to perform imaging of a radiation image in one frame by performing driving of a plurality of pixels <NUM> to use signals stored in the plurality of pixels <NUM> based on radiation irradiating the plurality of pixels <NUM> arranged in a matrix.

The drive circuit <NUM> drives the plurality of pixels <NUM> in the sensor array <NUM>, based on the control by the imaging control unit <NUM>.

The sensor array <NUM> includes the plurality of pixels <NUM> arranged in a matrix.

Specifically, the plurality of pixels <NUM> is two-dimensionally arranged in rows and columns in the sensor array <NUM>. Each of the pixels <NUM> includes a conversion element <NUM> to convert the incident radiation <NUM> into signal charge (an electric signal), and a switch element <NUM> such as a thin-film transistor (TFT) to transfer the electric signal to the outside. In the present exemplary embodiment, the conversion element <NUM> includes a scintillator (a fluorescence substance) to convert the incident radiation <NUM> into light such as visible light, and a photoelectric conversion element to convert the converted light into signal charge. The present exemplary embodiment is not limited to this configuration, and a conversion element of so-called direct conversion type with no scintillator to directly convert the incident radiation <NUM> into a signal can also be used as the conversion element <NUM>.

The drive circuit <NUM> switches the switch element <NUM> between ON and OFF via a drive line <NUM> to perform charge storage and charge readout of the conversion element <NUM>, providing a resultant radiation image. Specifically, the drive circuit <NUM> applies an ON voltage of the switch element <NUM> to a predetermined drive line <NUM> to switch ON the switch element <NUM> of each of the pixels <NUM> in the row connected to the predetermined drive line <NUM>. Subsequently, the charge of the conversion element <NUM> is amplified in the amplification circuit 203a via the corresponding one of the signal lines <NUM>, and held in the sample-and-hold circuit 203b. Afterward, the signals held in the sample-and-hold circuit 203b are sequentially read out via the multiplexer <NUM>, and then amplified by the amplifier <NUM>, and then converted into digital radiation image data by the A/D converter <NUM>. Further, the drive circuit <NUM> applies an OFF voltage of the switch element <NUM> to a predetermined drive line <NUM> to return each of the pixels <NUM> in the row in which the readout of the charge is completed to the charge storage state. The drive circuit <NUM> sequentially drives and scans the pixels <NUM> in each row of the sensor array <NUM>, and the signal charge of each of the pixels <NUM> is eventually converted into a digital value. That enables read out of the image data. Such driving and readout operations of the radiation imaging unit <NUM> are controlled by the imaging control unit <NUM> illustrated in <FIG>.

Further, the imaging control unit <NUM> sets the current operation state of the radiation imaging unit <NUM> based on information about the setting unit <NUM> holding an imaging order and imaging mode information specified by the system control apparatus <NUM>, and controls the driving of the radiation imaging unit <NUM>. Furthermore, in response of a receipt of an imaging request signal from the relay apparatus <NUM>, the imaging control unit <NUM> can perform imaging operation for a moving image for fluoroscopy or for a still image in synchronization with the relay apparatus <NUM>. Subsequently, the imaging control unit <NUM> performs image processing on image data acquired through the imaging operation, and then stores the image data in the storage unit <NUM> or transfers the image data to an external apparatus. Specifically, the image data is transferred from the radiation imaging apparatus <NUM> via the relay apparatus <NUM> to the system control apparatus <NUM>.

The pixels <NUM> in the sensor array <NUM> each have different characteristics from one another. Examples of main characteristic variations are variations in offset (dark current) and gain (conversion efficiency). To deal with those, the image data is subjected to offset correction, gain correction, and further, defective pixel correction, and these corrections in image processing are performed in either the radiation imaging apparatus <NUM> or an external apparatus such as the relay apparatus <NUM> or the system control apparatus <NUM>.

Here, <FIG> each illustrate a setting example of the setting unit <NUM> to hold an imaging mode and setting values (parameters) thereof specified by the system control apparatus <NUM> in the radiation imaging apparatus <NUM>.

The example in each of <FIG> include the imaging switch <NUM> and the fluoroscopy switch <NUM>, and further, either the pulse fluoroscopy or the continuous fluoroscopy can be set for the fluoroscopy switch <NUM>. The setting unit <NUM> can assign an imaging mode to each of three target switches, the fluoroscopy switch for the continuous fluoroscopy, the fluoroscopy switch for the pulse fluoroscopy, and the imaging switch. In the setting example in <FIG>, an imaging mode A is set for the fluoroscopy switch for the continuous fluoroscopy. The imaging mode A includes imaging parameters to be used for imaging: a frame rate of <NUM> fps, <NUM>×<NUM> pixel addition, a readout image region of <NUM> inches, and a gain setting <NUM>. Here, the frame rate is the reciprocal of frame time to read out signals of a radiation image in one frame from the plurality of pixels <NUM>. The pixel addition is to add the signals of the pixels <NUM> in a plurality of rows through simultaneous driving of the pixels <NUM> in the rows among the plurality of pixels <NUM>, and read out the added signals using the readout circuit <NUM>. A pixel addition number is the number of the added pixels, and <NUM>×<NUM> corresponds to the pixel addition number in this example. The readout image region is a region of the pixels <NUM> from which signals are read out by the readout circuit <NUM> through driving of the pixels <NUM> and that are some of the plurality of pixels <NUM>. The gain setting is a set amplification factor of the amplification circuit 203a, and expressed here by a numerical value at one of levels into which the amplification factors are classified. Further, an imaging mode B is set for the fluoroscopy switch for the pulse fluoroscopy. The imaging mode B includes imaging parameters to be used for imaging: a frame rate of <NUM> fps, <NUM>×<NUM> pixel addition, a readout image region of <NUM> inches, and a gain setting <NUM>. Furthermore, an imaging mode C is set for the imaging switch. The imaging mode C includes imaging parameters to be used for imaging: a frame rate of <NUM> fps, <NUM>×<NUM> pixel addition, a readout image region of <NUM> inches, and a gain setting <NUM>. The imaging modes A to C each can be a first mode or a second mode in some embodiments of the disclosure, and imaging performed in each of these modes can be first imaging or second imaging in some embodiments of the disclosure.

Based on these settings, the imaging control unit <NUM> performs driving control in the imaging operation of the imaging mode A in response to a receipt of an imaging request for the continuous fluoroscopy from the radiation source control apparatus <NUM>, and performs driving control in the imaging operation of the imaging mode B in response to a receipt of an imaging request for the pulse fluoroscopy. Further, in response to a receipt of an imaging request for the imaging switch, the imaging control unit <NUM> performs driving control in the imaging operation of the imaging mode C.

For example, the settings illustrated in <FIG> are used to perform imaging of a single still-image with the imaging switch <NUM> like still-image capturing (general imaging) without performing imaging with the fluoroscopy switch. In this case, the fluoroscopy switches for the continuous fluoroscopy and the pulse fluoroscopy are assigned settings indicating an invalid (not to be used) switch, and a still image mode D with imaging parameters that are a single frame, 1x1 pixel addition, a readout image region of <NUM> inches, and a gain setting <NUM> is set for the imaging switch. Here, for example, the frame time of this imaging may be applied to the single capturing parameter.

Next, a procedure example of imaging operation in the entire radiation imaging system <NUM> will be described with reference to <FIG>. First, upon the system activation, information indicating that the fluoroscopy mode is selected is notified to the radiation imaging apparatus <NUM> via the relay apparatus <NUM> based on the state of the fluoroscopy switch <NUM> of the radiation source control apparatus <NUM>, before imaging is performed (at timing TC401). A user selects an imaging protocol, using the input device <NUM> of the system control apparatus <NUM> (at timing TC402). Based on the selected imaging protocol, designated commands are notified from the system control apparatus <NUM> via the relay apparatus <NUM> to the radiation imaging apparatus <NUM> (at timing TC403), and set in the setting unit <NUM>. Here, the designated commands include the imaging mode A to be set for the continuous fluoroscopy, the imaging mode B to be set for the pulse fluoroscopy, and the imaging mode C to be set for the still-image capturing. Here, due to the pulse-fluoroscopy selected state at the timing TC401, the imaging control unit <NUM> may switch the standby mode to the imaging mode B set for the pulse fluoroscopy.

Subsequently, the imaging switch <NUM> is pressed and then the imaging operation of the imaging mode C is performed (at timing TC404). Control <NUM> at the time of starting the imaging will be described with reference to <FIG>.

<FIG> is a timing chart illustrating a driving switching control example in starting imaging in the radiation imaging apparatus <NUM>. For example, at timing TC501, the standby driving is controlled with the parameters of the imaging mode B, as the standby driving for no imaging. Here, control of repeating storage and readout is performed at the frame rate or in the frame time defined in the imaging mode B. As this control is performed in the standby period for no imaging, image data read out from the radiation imaging unit <NUM> is not transferred to an external apparatus such as the system control apparatus <NUM>. Next, the preparation switch is pressed at timing TC502, and the request switch is pressed at timing TC503. Here, the imaging mode C is set for the imaging switch in the setting unit <NUM>. The imaging mode in the current standby operation and the set imaging mode are different, and the imaging control unit <NUM> starts switching control at timing TC504. Here, the switching control has been described to start at the timing TC504, but may start at the timing TC503. In the switching control, readout driving is performed a plurality of times to solve instability of charge generated in the radiation imaging unit <NUM> immediately after switching to an imaging mode with different imaging parameters. At the timing TC504, for example, immediately after the start of switching, the readout driving for the imaging mode C after the switching is performed a plurality of times sequentially, releasing charge in the pixels. Subsequently, the readout driving is performed once at the same frame rate and with the same imaging parameters as those of the imaging mode C, as a preparation for the imaging operation in the imaging mode C. This completes the mode switching control, and at timing TC505 for the next storage, the control is performed of emitting the radiation (timing TC506), and the imaging operation based on the imaging mode C after the switching begins. Upon start of the imaging operation, image data acquired based on the readout control is transferred to an external apparatus (at timing TC507).

Here, the switching control is not limited to the example described above.

For example, it is conceivable to use a method of performing the readout driving a fixed number of times at the same frame rate and with the same imaging parameters as those of the imaging mode after the switching. It is also conceivable to use a method of performing the readout driving for the imaging mode after the switching a fixed number of times at a cycle higher than the frame rate of the imaging mode after the switching.

With the standby mode for no imaging different from the set imaging mode, the switching control is performed with a mode switching time T_mc between the press of the switch and the actual imaging operation. This mode switching time is uniquely defined based on the imaging mode after the switching.

Referring back to <FIG>, the imaging switch <NUM> is released at timing TC405, and the imaging in the imaging mode C ends. In response to the end of the imaging (the first imaging) in the imaging mode C, the selection unit <NUM> selects a setting value for the standby driving by selecting a standby mode from the setting information about the setting unit <NUM>. In this case, the setting value for the standby driving is set to the setting value for the imaging mode B, by selecting the imaging (the second imaging) in the imaging mode B set for the pulse fluoroscopy. In response to this setting, the standby operation is performed with the setting value for the imaging mode B, so that the mode switching control is performed. After the mode switching time T_mc, the mode switching is completed, and the standby state begins with the standby driving set based on the setting value for the imaging mode B (at timing TC406). Here, the setting value for the standby driving may not be set to the setting value for the standby driving with the second setting value as the setting value for the second imaging, and a second setting value as the setting value for the standby driving closer than the first setting value as the setting value for the first imaging can reduce or decrease an artifact after the switching. The standby operation is to drive the plurality of pixels <NUM> to reduce or decrease the signals (or the amount of dark current components) stored in the plurality of pixels <NUM> during the period in which the plurality of pixels <NUM> is not irradiated with the radiation. The end of the imaging can be performed in response to the end of the press of the switch, or may be performed in response to the end of the driving for the plurality of pixels in the imaging or the end of the readout therefrom. Moreover, not all the setting values may be used, and if the operation is performed for at least one setting value, an effect of this setting value is produced.

Subsequently, when the fluoroscopy switch <NUM> is pressed with the pulse fluoroscopy mode selected (at timing TC407), the parameters set for the pulse fluoroscopy and the parameters for the current standby operation match each other. This allows the fluoroscopic imaging in the imaging mode B to start without performing the switching control separately during the standby period. Control <NUM> at the start of the fluoroscopic imaging will be described with reference to <FIG>.

If the imaging parameters for the standby operation for no imaging and the imaging parameters for the set imaging mode match each other as illustrated by an example in <FIG>, the switching control will not be performed separately. Thus, after the timing of the press of the imaging request switch (at timing TC603), control of the irradiation of the radiation at timing TC605 and start of the imaging operation are possible at the next storage start timing TC604. In this case, a variation in the time by a frame rate cycle T_cyc however occurs after the timing of the press of the switch and before the imaging operation actually begins, causing a delay of a T_cyc time at maximum to occur. In standby in an imaging mode at a high frame rate, the T_cyc time is short and thus does not matter, but in standby in an imaging mode at a low frame rate, the frame rate cycle T_cyc can be longer than the mode switching time T_mc. A frame rate in a fluoroscopy mode is typically higher than in an imaging mode for imaging a still image, and it thus is suitable that a setting value for the fluoroscopy mode is selected as a setting value for the standby driving.

<FIG> is a flowchart illustrating a processing example in the selection unit <NUM> of the radiation imaging apparatus <NUM> according to the first exemplary embodiment.

In step S701, the selection unit <NUM> determines whether the imaging operation such as the fluoroscopic imaging, the still-image capturing, or the continuous imaging is terminated. If the imaging operation is terminated (YES in step S701), the processing proceeds to step S702 to start determination as to the selection for the standby driving. In step S702, with the imaging switch <NUM> composed of the preparation switch and the request switch as a two-phase switch, the state of each of these switches being to be notified from the radiation source control apparatus <NUM> to the radiation imaging apparatus <NUM>, the selection unit <NUM> checks whether the preparation switch is still in a pressed state after the imaging operation is terminated. If the preparation switch alone is pressed (YES in step S702), the imaging operation by the imaging switch <NUM> is likely to be performed next. For that reason, the processing proceeds to step S715, and in step S715, the selection unit <NUM> selects a setting value for an imaging mode set for the imaging switch <NUM> in the setting unit <NUM>, as a setting value for the standby driving. Despite the description as in step S715 in the processing example, a low frame rate of the imaging mode set for the imaging switch <NUM> may cause the frame rate cycle T_cyc to be longer than the mode switching time T_mc for switching to that imaging mode. In this case, the processing may proceed to step S703 in which the selection unit <NUM> selects a setting value for the standby driving, other than the setting value for the imaging mode set for the imaging switch <NUM>.

If the preparation switch is not pressed (NO in step S702), the processing proceeds to step S703. In step S703, the selection unit <NUM> checks whether a valid imaging mode is set for the fluoroscopy switch <NUM> of either the continuous fluoroscopy or the pulse fluoroscopy. If the setting of invalid (not to be used) is made for both of these switches (NO in step S703), the processing proceeds to step S714. In step S714, the selection unit <NUM> selects a setting value for an imaging mode with a high frame rate as a setting value for the standby driving from the imaging modes that can be performed by the imaging control unit <NUM>.

If a valid imaging mode is assigned to the fluoroscopy switch <NUM> (YES in step S703), the processing proceeds to step S704. In step S704, the selection unit <NUM> determines whether which of the continuous fluoroscopy mode and the pulse fluoroscopy mode is selected in the radiation source control apparatus <NUM> can be checked in advance. This information is notified via the relay apparatus <NUM> to the radiation imaging apparatus <NUM>, in response to, for example, a switching operation on the selection switch <NUM>. However, a system of notifying the fluoroscopy mode selection information at the moment of a press of the fluoroscopy switch alone as an example will have difficulty checking in advance. In this case (NO in step S704), the processing proceeds to step S711, and in step S711, the selection unit <NUM> determines whether the previously performed fluoroscopy is the pulse fluoroscopy. If the previously performed fluoroscopy is the pulse fluoroscopy (YES in step S711), the processing proceeds to step S712, and in step S712, the selection unit <NUM> selects a setting value for the pulse fluoroscopy as a setting value for the standby driving. Otherwise (NO in step S711), the processing proceeds to step S713, and in step S713, the selection unit <NUM> selects a setting value for the continuous fluoroscopy as a setting value for the standby driving.

If which one of the continuous fluoroscopy mode and the pulse fluoroscopy mode is selected can be checked in advance (YES in step S704), the processing proceeds to step S705. In step S705, the selection unit <NUM> determines whether the pulse fluoroscopy is selected. If the pulse fluoroscopy is selected (YES in step S705), the processing proceeds to step S706, and in step S706, the selection unit <NUM> selects a setting value for the pulse fluoroscopy as a setting value for the standby driving. If the continuous fluoroscopy is selected (NO in step S705), the processing proceeds to step S707, and in step S707, the selection unit <NUM> selects a setting value for the continuous fluoroscopy as a setting value for the standby driving.

In step S708, whether the setting value for the standby driving thus selected by the selection unit <NUM> is the same as the setting value for the imaging mode in the current imaging operation is determined. If the selected setting value is different from the setting value for the imaging mode in the current imaging operation (NO in step S708), the processing proceeds to step S710, and in step S710, switching control is immediately performed based on the setting value for the standby driving. If the selected setting value is the same as the setting value for the imaging mode in the current imaging operation (YES in step S708), the processing proceeds to step S709, and in step S709, switching for driving is not performed.

As described above, performing the standby driving suitable for the next fluoroscopy reduces the delay from the press of the fluoroscopy switch to the start of the fluoroscopic imaging operation on the radiation imaging apparatus used as the fluoroscopic apparatus. The pulse fluoroscopy, the still-image capturing, and the continuous fluoroscopy each have been described above as an imaging operation, but, for example, operation of acquiring an image without emitting the radiation and acquiring offset correction data for correcting the offset component may also be included as one imaging operation.

Next, a second exemplary embodiment will be described with reference to <FIG> and <FIG>. As illustrated in <FIG>, a radiation imaging system <NUM> in the second exemplary embodiment includes a plurality of radiation sources, i.e., a radiation source <NUM> and a radiation source <NUM> used for, for example, a fluoroscopic table <NUM> and an upright support <NUM>, respectively. A radiation imaging apparatus <NUM> used in the fluoroscopic table <NUM> is connected to a connection terminal <NUM> of a wire cable for use to perform imaging operation such as pulse fluoroscopy, continuous fluoroscopy, and still-image capturing. A cooling device (not illustrated) such as an air-cooling device is separately held in the fluoroscopic table <NUM> to stabilize the temperature of the radiation imaging apparatus <NUM>.

Here, the radiation imaging apparatus <NUM> can be easily taken out of the fluoroscopic table <NUM>, and can be disconnected from the connection terminal <NUM> of the wire cable and moved. The radiation imaging apparatus <NUM> can be then connected to a connection terminal <NUM> of a wire cable of the upright support <NUM> to perform the still-image capturing as general imaging in the upright support <NUM>. The radiation imaging apparatus <NUM> can determine which one of the connection terminals of the wire cables is connected thereto, and thus can determine whether the radiation imaging apparatus <NUM> is to be used in the fluoroscopic table <NUM> or the upright support <NUM>. One conceivable method as an example is of holding in a relay apparatus <NUM> a setting indicating which one of the connection terminal <NUM> of the wire cable for the fluoroscopic table <NUM> and the connection terminal <NUM> of the wire cable for the upright support <NUM> is to be used, and notifying the setting through command communication with the radiation imaging apparatus <NUM> connected. Here, although the radiation imaging apparatus <NUM> used in the upright support <NUM> is connected to the connection terminal <NUM> of the wire cable, the radiation imaging apparatus <NUM> can be used through wireless communication using an AP <NUM>, instead of the wire connection. The radiation imaging apparatus <NUM> can be used for imaging at any location through wireless communication, in addition to the use in the fluoroscopic table <NUM> and the upright support <NUM>. In this case, the radiation imaging apparatus <NUM> operates on a built-in battery. In the present exemplary embodiment, the configurations of the radiation imaging apparatus <NUM>, a radiation source control apparatus <NUM>, the relay apparatus <NUM>, and a system control apparatus <NUM> are similar to those of the first exemplary embodiment.

In the radiation imaging system <NUM> described above, the radiation imaging apparatus <NUM> operating on a built-in battery out of the fluoroscopic table <NUM> will consume the battery more if standby operation is performed in an imaging mode for fluoroscopic, as in the fluoroscopic table <NUM>, for example. In addition, the radiation imaging apparatus <NUM> taken out of the fluoroscopic table <NUM> is also separated from the cooling device, and the configuration involves preventing a temperature rise in the radiation imaging apparatus <NUM>.

<FIG> is a flowchart illustrating a processing example in a selection unit <NUM> of the radiation imaging apparatus <NUM> according to the second exemplary embodiment of the disclosure. In step S901, the selection unit <NUM> checks whether the radiation imaging apparatus <NUM> is in use in the fluoroscopic table <NUM>. If the radiation imaging apparatus <NUM> is out of use in the fluoroscopic table <NUM> (NO in step S901), the processing proceeds to step S903. In step S903, the selection unit <NUM> selects to a setting value for the standby driving a setting value for an imaging mode for power saving of reducing power consumption down to a level lower than that in the image operation to prevent a rise in power consumption and temperature of the radiation imaging apparatus <NUM>. If the radiation imaging apparatus <NUM> is in use in the fluoroscopic table <NUM> (YES in step S901), the processing proceeds to step <NUM>. In step S902, the selection unit <NUM> selects a setting value for the standby driving in the fluoroscopic table <NUM>. For the selection processing for the setting value for the standby driving in the fluoroscopic table <NUM> (step S902), specifically, for example, it is conceivable to use a method similar to the processing of selecting the setting value for the standby driving in the first exemplary embodiment in <FIG>.

Subsequently, in step <NUM>, whether the selected setting value for the standby driving is the setting value for the current imaging mode in which an imaging control unit <NUM> is in operation is determined. If the selected setting value for the standby driving is different from the setting value for the current imaging mode (NO in step S904), the processing proceeds to step S906, and in step S906, the setting value is switched to the selected setting value for the standby driving. If the selected setting value for the standby driving is the setting value for the current imaging mode (YES in step S904), the processing proceeds to step S905, and in step S905, the standby driving is performed as it is.

According to the second exemplary embodiment, the setting value for the standby driving can be selected as appropriate based on the use state. For example, in use in the fluoroscopic table <NUM>, a setting value selected beforehand for the standby driving suitable for the next fluoroscopic operation allows the delay from the press of a fluoroscopy switch to the start of the fluoroscopy imaging operation to be reduced. In addition, in use outside the fluoroscopic table <NUM>, a switched setting value for the standby driving for power saving allows reduction of a rise in temperature and power consumption.

The disclosure can also be implemented by processing for loading a program for implementing one or more functions in any of the above-described exemplary embodiments to a system or apparatus via a network or a storage medium and causing one or more processors in a computer of the system or apparatus to read and run the program. The disclosure can also be implemented by a circuit (for example, an application specific integrated circuit (ASIC)) that implements the one or more functions.

Embodiment(s) of the disclosure can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a 'non-transitory computer-readable storage medium') to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s).

According to the exemplary embodiments of the disclosure, a radiation imaging apparatus is provided that can perform imaging in a plurality of imaging modes, and that can control switching to an imaging mode suitable for use as a fluoroscopic apparatus during a standby period.

Claim 1:
A radiation imaging apparatus comprising:
radiation imaging means for performing imaging of a radiation image in one frame by performing driving of a plurality of pixels to use signals stored in the plurality of pixels based on radiation irradiating the plurality of pixels arranged in a matrix; and
imaging control means for controlling the imaging by controlling the driving based on a setting value,
wherein the imaging control means causes the radiation imaging means to perform the imaging in a plurality of modes varying in the setting value, and
wherein the imaging control means causes the radiation imaging means to perform standby driving of the plurality of pixels to reduce signals stored in the plurality of pixels during a period in which the plurality of pixels is not irradiated with radiation, the plurality of modes including a first mode in which the radiation imaging means performs first imaging using a first setting value and a second mode in which the radiation imaging means performs second imaging using a second setting value different from the first setting value after the first imaging, and the imaging control means causes the radiation imaging means to perform the standby driving using the setting value closer to the second setting value than to the first setting value in response to end of the first imaging in causing the radiation imaging means to perform the second imaging.