Patent Publication Number: US-2009232278-A1

Title: Radiation image detector and radiation imaging system

Description:
TECHNICAL FIELD 
     The present invention relates to a radiation image detector and a radiation imaging system, and more particularly to a radiation image detector and a radiation imaging system for imaging a radiation image as represented by an X-ray image. 
     BACKGROUND ART 
     In the field of medical diagnosis, there has been widely used a radiation image which is obtained by irradiating a subject with radiation such as X-ray and detecting an intensity distribution of the radiation having transmitted through the subject. In recent years, with respect to imaging, there has been proposed a radiation imaging system using an FPD (flat panel detector; radiation image detector), which detects the radiation, converts the detected radiation into electric energy, and detects the electric energy as radiation image data. 
     Recently, there has been developed a cassette-shaped FPD in which the FPD is accommodated in a cassette for the purpose of improving the portability and easy handling of the FPD (see, for example, Patent Document 1). Particularly, in order to utilize the portability of the FPD, there has been developed a cassette-shaped FPD which performs wireless communication with a console controlling the FPD. The wireless-type cassette FPD is not supplied power from other equipment, therefore has a battery embedded therein. In order to use the battery as long as possible, the cassette-shaped FPD is configured to switch between a state of large power consumption, e.g., at the time of radiographing (imaging ready state) and a state of small power consumption, e.g., at the time of standby (imaging standby state). In the imaging ready state, power is supplied to every part necessary for radiographing in the cassette-shaped FPD. On the other hand, in the imaging standby state, power is supplied to necessary parts for at least receiving various instructions, that is, an electrode is not supplied to any part unnecessary for receiving various instructions although these parts are necessary for radiographing. 
     Patent Document 1: JP H6-342099A 
     DISCLOSURE OF THE INVENTION 
     Problems to be solved by the Invention 
     Since the wireless-type cassette-shaped FPD is not supplied power from other equipment, sometimes power is not sufficiently supplied because of insufficient remaining power even if radiographing is performed after switching to the imaging ready state from the imaging standby state. When the power is not sufficiently supplied for radiographing, some malfunctions occur, for example, signals cannot be read, an accurate diagnosis cannot be performed because of an unclear radiation image even if the signals are read, and so on. Further, read image data are usually stored in a memory, but when the power is not sufficiently supplied, the memory does not work normally, and the image data are possible to be deleted. When the image data are to be transmitted to an external device such as a console, the transmission cannot be performed if the power supply is not enough. In any case mentioned above, a patient is forced to be radiographed again and unnecessarily exposed to radiation. 
     An object of the invention is to prevent radiographing from being performed under insufficient remaining power of a battery, to suppress frequency of re-radiographing, and hence to prevent a patient from unnecessary exposure to radiation. 
     Means for Solving the Problem 
     The radiation image detector according to the invention of claim  1  is a radiation image detector switchable between an imaging ready state which can detect radiation and an imaging standby state in which power consumption is less than that of the imaging ready state, the detector comprising: 
     a switching unit for giving an instruction of switching between the imaging ready state and the imaging standby state; 
     a chargeable or replaceable battery provided as a power supply source for supplying power to a plurality of drive units; 
     a battery remaining power detecting section for detecting a remaining power of the battery; and 
     a control unit for controlling running states of the plurality of drive units to switch between the imaging ready state and the imaging standby state according to the instruction from the switching unit and for controlling the battery remaining power detecting section, 
     wherein the control unit controls the running states of the plurality of drive units to switch from the imaging standby state to the imaging ready state on the basis of a detected result of the remaining power of the battery, by the battery remaining power detecting section. 
     According to the invention of claim  1 , the detector can be switched from the imaging standby state to the imaging ready state based on the detected result of the remaining power of the battery with the battery remaining power detecting section, and therefore when the remaining power of the battery is not sufficient, the detector can be controlled not to be switched to the imaging ready state. This allows prevention of radiographing under insufficient remaining power of the battery. 
     The invention of claim  2  is a radiation image detector of claim  1 , wherein the control unit controls the running states of the plurality of drive units to switch between the imaging ready state and the imaging standby state on the basis of the detected result of the remaining power by the battery remaining power detecting section at the time when an radiographing instruction for switching from the imaging standby state to the imaging ready state is input from the switching unit. 
     According to the invention of claim  2 , on the basis of the detected result of the remaining power detected by the battery remaining power detecting section at the time when the radiographing instruction is input from the switching unit, the detector can be switched between the imaging ready state and the imaging standby state, thereby being automatically switched to a state suitable for the remaining power of the battery prior to radiographing. 
     The invention of claim  3  is a radiation image detector of claim  2 , wherein the control unit controls the running states of the plurality of drive units such that the detector goes into the imaging ready state when the detected result of the remaining power in the battery remaining power detecting section, at the time when the radiographing instruction is input from the switching unit, satisfies the power possible to radiographto radiograph, and goes into the imaging standby state when the detected result is less than the power possible to radiographto radiograph. 
     According to the invention of claim  3 , the detector goes into the imaging ready state when the detected result of the remaining power in the battery remaining power detecting section, at the time when the radiographing instruction is input from the switching unit, satisfies the power possible to radiographto radiograph, and goes into the imaging standby state when the detected result is less than the power possible to radiographto radiograph. This can securely prevent the radiographing from being performed with the remaining power less than that possible to radiographto radiograph. 
     The invention of claim  4  is a radiation image detector of claim  3 , further comprising a notifying unit for notifying on the basis of the control of the control unit, wherein the control unit controls the notifying unit to notify that the radiographing is not permitted when the detected result of the remaining power in the battery remaining power detecting section, at the time when the radiographing instruction is input from the switching unit, is less than the power possible to radiographto radiograph. 
     According to the invention of claim  4 , at the time when the radiographing instruction is input from the switching unit, the notifying unit notifies that the radiographing is not permitted when the detected result of the remaining power in the battery remaining power detecting section, is less than the power possible to radiographto radiograph, and therefore the radiographer can carry out, e.g., replacement, charging of the battery based on the notice. 
     The invention of claim  5  is a radiation image detector of any one of claims  1  to  4 , wherein the imaging standby state has a plurality of modes, and wherein the control unit controls the running states of the plurality of drive units so that the plurality of modes have respective different power consumptions. 
     According to the invention of claim  5 , the imaging standby state includes a plurality of modes with respective different power consumptions, and therefore the radiation image detector can be set to the most suitable state according to, e.g., its use condition after completion of charging or replacement of the battery. This allows suppression of useless power consumption, and allows efficient radiographing work. 
     The invention of claim  6  is a radiation image detector of claim  5 , wherein the control unit controls the running states of the plurality of drive units such that the detector goes into a mode of minimum power consumption in the plurality of modes in the imaging standby state when the detected result of the remaining power in the battery remaining power detecting section, at the time when the radiographing instruction is input from the switching unit, is less than the power possible to radiographto radiograph. 
     According to the invention of claim  6 , when the detected result of the remaining power in the battery remaining power detecting section, at the time when the radiographing instruction is input from the switching unit, is less than the power possible to radiographto radiograph, the detector goes into the mode of minimum power consumption out of the plurality of modes in the imaging standby state, and therefore the power consumption can be reduced as much as possible when radiographing is not permitted. 
     The invention of claim  7  is a radiation image detector of claims  5  or  6 , wherein the control unit controls the battery remaining power detecting section to detect the remaining power of the battery when a standby-state switching instruction for switching from a mode of smaller power consumption to a mode of larger power consumption in the plurality of modes is input from the switching unit, the standby-state switching instruction. 
     When provided with a plurality of imaging standby states with respective different power consumptions, it is possible to switch the imaging standby state according to a condition at the time of standby. The radiation image detector includes parts which have a characteristic of deterioration with time when power is supplied (such as photodiodes and thin film transistors). The photodiodes and the thin film transistors need a longer time to go into their stable states when power is supplied again after stopped. Accordingly, it is possible that: when radiographing is not performed for a while, an imaging standby mode, in which power is not supplied to the photodiodes and the thin film transistors, is set, and when radiographing will soon be performed, an imaging standby mode, in which power is supplied to the photodiodes and the thin film transistors, is set. On the contrary, ICs for reading and the like have large power consumption and need not a longer time to go into their stable states, therefore may be set to an imaging standby mode in which power is not supplied until just before radiographing. As will be understood from these examples, when the imaging standby state of less power consumption is transferred to the imaging standby state of larger power consumption out of the plurality of imaging standby states, it is probable that radiographing will soon be performed. That is, according to the invention as described in claim  7 , if the remaining power of the battery is detected when a standby-state switching instruction, for switching from the imaging standby state of less power consumption to the imaging standby state of larger power consumption, is input from the switching unit, the remaining power of the battery can be recognized prior to radiographing. This allows determination prior to the radiographing as to whether the detector can perform radiographing normally, and hence prevents the radiographing from being performed under insufficient remaining power of the battery. 
     The invention of claim  8  is a radiation image detector of any one of claims  1  to  7 , further comprising: 
     a check unit for performing an operation check of the drive units as to whether the drive units can work normally when the detector starts to operate; and 
     a control unit for controlling the running states of the plurality of drive units on the basis of the result of the operation checks. 
     According to the invention of claim  8 , the radiation image detector, which detects irradiated radiation to obtain radiation image data, includes the plurality of drive units, the check unit for performing operation checks of the drive units as to whether the drive units can work normally when the detector starts operating, and a control unit for controlling the running states of the plurality of drive units based on the result of the operation checks. Therefore, the radiation image detector can perform operation checks of the drive units prior to radiographing. This allows determination prior to the radiographing as to whether the drive units can work normally, and hence prevents the radiographing from being performed while the drive units do not work normally. 
     The invention of claim  9  is a radiation image detector of claim  8 , 
     wherein the running state includes an ON state of a main power source, the ON state including an imaging ready state which can detect radiation and an imaging standby state in which power consumption is less than that of the imaging ready state; and an OFF state of the main power source in which power supply to the drive units is completely shut off, and 
     wherein when the check unit detects that one of the drive units cannot work normally, the detector is not switched at least to the imaging ready state. 
     According to the invention of claim  9 , the running state includes an ON state of a main power source, the ON state including an imaging ready state which can detect radiation and an imaging standby state in which power consumption is less than that in the imaging ready state; and an OFF state of the main power source in which power supply to the drive units is completely shut off. When the check unit detects that some of the drive units cannot work normally, the detector is not switched at least to the imaging ready state. Accordingly, the running state of the radiation image detector can be switched between the ON state, including the imaging ready state and the imaging standby state, and the OFF state of the main power source, and further the control unit controls the plurality of drive units so as to switch to the imaging standby state or the OFF state of the main power source when the check unit detects as the result of the operation checks that respective drive units cannot work normally. 
     The invention of claim  10  is a radiation image detector of claim  9 , wherein when the battery remaining power detecting section detects that the remaining power of the power source is less than a predetermined power possible to radiographto radiograph, the control unit causes the detector to go into the OFF state of the main power source. 
     According to the invention of claim  10 , when the battery remaining power detecting section detects that the remaining power of the power source is less than a predetermined power possible to radiographradiograph, the control unit causes the detector to go into the OFF state of the main power source. Therefore, in the radiation image detector, when the result of the remaining power, detected by the battery remaining power detecting section, indicates that the remaining power of the power source is less than a predetermined power possible to radiograph, the control unit controls the running states of the plurality of drive units so that the detector is in the OFF state of the main power source, and prevents the detector from starting operation. 
     The invention of claim  11  is a radiation image detector of claim  9 , 
     wherein the imaging standby state includes a first imaging standby mode, and a second imaging standby mode in which power consumption is less than that of the first imaging standby mode, and 
     the detector further comprises a communication unit as the drive unit; and a communication check unit for performing communication check of the communication unit as the operation check. 
     According to the invention of claim  11 , the imaging standby state includes the first imaging standby mode, and the second imaging standby mode in which power consumption is less than that in the first imaging standby mode. The detector further includes the communication unit as the drive unit, and the communication check unit for performing a communication check of the communication unit as the operation check. Therefore, the control unit can control the running states of the plurality of drive units according to the result of the communication check. 
     The invention of claim  12  is a radiation image detector of claim  11 , wherein when the communication check unit detects that the communication unit cannot work normally, the control unit causes the detector to go into the second imaging standby mode. 
     According to the invention of claim  12 , when the communication check unit detects that the communication unit cannot work normally, the control unit causes the detector to go into the second imaging standby mode. Therefore, the control unit controls the running states of the plurality of drive units so that the detector can go into the second imaging standby mode when the communication check unit detects that the communication unit cannot work normally, and enables the radiation image detector to run in a state of less power consumption. 
     The invention of claim  13  is a radiation image detector of claim  14 , further comprising a notifying unit for performing notification on the basis of the control of the control unit, wherein when the communication check unit detects that the communication unit cannot work normally, the notifying unit notifies that the communication unit is impossible to work normally. 
     According to the invention of claim  13 , the detector further includes a notifying unit for notifying based on the control of the control unit, and when the communication check unit detects that the communication unit cannot work normally, the notifying unit notifies that the communication unit is impossible to work normally. Therefore, the control unit can notify through the notifying unit that the communication unit is impossible to work normally when the communication unit cannot work normally. 
     The invention of claim  14  is a radiation image detector of claim  9 , 
     wherein the imaging standby state includes a first imaging standby mode, and a second imaging standby mode in which power consumption is less than that of the first imaging standby mode, and 
     the detector further comprises an image storing unit as the drive unit; and a memory check unit for performing a memory check of the image storing unit as the operation check. 
     According to the invention of claim  14 , the imaging standby state includes the first imaging standby mode, and the second imaging standby mode in which power consumption is less than that in the first imaging standby mode. The detector further includes an image storing unit as the drive unit, and a memory check unit for performing a memory check of the image storing unit as the operation check. Therefore, the control unit can control the running states of the plurality of drive units according to the result of the memory check of the image storing unit. the control unit controls the running states of the plurality of drive units so that the detector can go into the second imaging standby mode when, and enables the radiation image detector to run in a state of less power consumption. 
     The invention of claim  15  is a radiation image detector of claim  14 , wherein when the memory check unit detects that the image storing unit cannot work normally, the control unit causes the detector to go into the second imaging standby mode. 
     According to the invention of claim  15 , when the memory check unit detects that the image storing unit cannot work normally, the control unit causes the detector to go into the second imaging standby mode. Therefore, the control unit controls the running states of the plurality of drive units so that the detector can go into the second imaging standby mode when the memory check unit detects that the image storing unit cannot work normally, and enables the radiation image detector to run in a state of less power consumption. 
     The invention of claim  16  is a radiation image detector of any one of claims  1  to  15 , wherein the detector is a cassette-shaped flat panel detector which detects irradiated radiation, converts the radiation to electric signals, accumulates the electric signals, and reads the accumulated electric signals to obtain radiation image data. 
     According to the invention of claim  16 , the radiation image detector is a cassette-shaped FPD, therefore possible to be easily carried regardless of radiographing places, thereby improving flexibility of radiographing. Moreover, even when such a radiation image detector is used for radiographing, the radiation image detector can be set to the imaging ready state or the imaging standby state according to, e.g., its use condition after completion of charging or replacement of the battery, whereby the invention achieves effects that useless power consumption is suppressed and efficient radiographing work can be performed. 
     The invention of claim  17  is a radiation imaging system comprising: 
     the radiation image detector of any one of claims  1  to  16 ; and 
     a console which controls the radiation image detector. 
     According to the invention of claim  17 , the radiation imaging system can achieve the same actions and effects as of the inventions described in claims  1  to  16 . 
     The invention of claim  18  is a radiation imaging system of claim  17 , 
     wherein the console comprises a display unit which displays on the basis of the control of the control unit, and 
     the control unit controls the display unit to display that the radiographing is not permitted when the detected result of the remaining power in the battery remaining power detecting section, at the time when the radiographing instruction is input from the switching unit, is less than the power possible to radiographto radiograph. 
     According to the invention of claim  18 , the invention can achieve the same action and effect as of the invention of claim  4 . 
     The invention of claim  19  is a radiation imaging system of claim  18 , wherein the control unit controls the display unit to display the remaining power of the battery on the basis of the detected result in the battery remaining power detecting section. 
     According to the invention of claim  19 , the remaining power of the battery is displayed on the display unit of the console, whereby the remaining power of the battery can be visually recognized. This allows speedy dealing of charging or replacement of the battery. 
     The invention of claim  20  is a radiation imaging system of claims  18  or  19 , wherein the control unit controls the display unit to display whether the radiation image detector is in the imaging ready state or the imaging standby state. 
     According to the invention of claim  20 , there is displayed on the display unit of the console as to whether the radiation image detector is in the imaging ready state or the imaging standby state. Therefore, the present state of the radiation image detector can be visually recognized. 
     The invention of claim  21  is a radiation imaging system comprising: 
     the radiation image detector of any one of claims  8  to  15 ; and 
     a console which controls the radiation image detector, 
     wherein the console comprises a notifying unit which notifies either one or both of the running state of the radiation image detector and the result of operation checks of the radiation image detector. 
     According to the invention of claim  21 , the console includes a notifying unit which notifies either one or both of the running state of the radiation image detector and the result of operation checks of the radiation image detector. Therefore, the console can notify, through the notifying unit, the running state and checked state by the check unit in the radiation image detector. 
     EFFECTS OF THE INVENTION 
     According to the invention, it is possible to determine prior to radiographing whether normal radiographing can be performed. Therefore, radiographing with insufficient remaining power of a battery can be prevented, the frequency of re-radiographing is suppressed, and a patient can be prevented from unnecessary exposure to radiation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  This is a view showing a schematic configuration illustrating one embodiment of a radiation imaging system according to the present invention. 
         FIG. 2  This is a perspective view showing a structure of main elements of a radiation image detector according to the present invention. 
         FIG. 3  This is a block diagram showing a configuration of main units of the radiation image detector according to the present invention. 
         FIG. 4  This is an equivalent circuit diagram for one pixel in a photoelectric conversion unit constituting a signal detection unit included in the radiation image detector of  FIG. 2 . 
         FIG. 5  This is an equivalent circuit diagram in which the photoelectric conversion units shown in  FIG. 4  are arranged two-dimensionally. 
         FIG. 6  This is a block diagram showing a configuration of main units of a console included in the radiation imaging system of  FIG. 1 . 
         FIG. 7  This is a perspective view showing a radiation image detector of a third embodiment. 
         FIG. 8  This is a block diagram showing a configuration of main units of the radiation image detector of the third embodiment. 
     
    
    
     PREFERRED EMBODIMENTS OF THE INVENTION 
     First Embodiment 
     An embodiment of the present invention will be described below with reference to  FIGS. 1 to 6 . 
       FIG. 1  is a view showing a schematic configuration of one embodiment of a radiation imaging system including a radiation image detector according to the invention applied thereto. 
     A radiation imaging system  1  of the embodiment is a system, which is, for example, applied to radiation imaging performed in a hospital. As shown in  FIG. 1 , the system  1  includes a server  2  that manages various kinds of information concerning the radiographing and a patient, an radiographing operation device  3  that performs operations associated with the radiation imaging, a base station  4  that performs communication, e.g., by a wireless communication system such as a wireless LAN (local area network), a console  6  that controls a radiation image detector  5  and executes image processing on a radiation image detected by the radiation image detector  5 , and a network  7  through which devices  2 ,  3 ,  4 ,  5  and  6  are connected to each other. The radiographing operation device  3  is connected through a cable  8  to a radiation imaging device  10  that irradiates the patient as a subject  9  with radiation to perform radiation imaging. The radiation imaging device  10  and radiation image detector  5  are, for example, installed by one device in one radiographing room  11 , and radiation image data can be obtained by operating the radiation imaging device  10  with the radiographing operation device  3  and detecting the radiation image with the radiation image detector  5 . Alternatively, a plurality of radiation image detectors  5  may be provided in one radiographing room  11 . 
     The network  7  may be a communication line dedicated to the system; however, the network  7  is preferably an existing line such as Ethernet (registered trademark) because otherwise the flexibility of system configuration would be reduced, or for other reasons. In addition to the devices represented above, there may be connected to the network  7  a plurality of radiographing operation devices  3  that operate radiation imaging devices  10  installed in other radiographing rooms  11 , radiation image detectors  5 , and consoles  6 . 
     First, the radiographing operation device  3  includes an input operation unit (not shown) that operates the radiation imaging device  10  by, e.g., inputting signals of radiographing conditions or the like, the input operation unit (not shown) including an operation panel and the like; a display unit (not shown) that displays information about the radiographing conditions etc., various instructions and the like; and a power supply unit (not shown) that supplies power to the radiation imaging device  10 . 
     The radiation imaging device  10  is arranged in the radiographing room  11 . The radiation imaging device  10  includes a radiation source  12 . radiation is generated by applying a tube voltage to the radiation source  12 . for example, a radiation tube is used for the radiation source  12 . The radiation tube generates radiation by colliding accelerated electrons generated by thermal excitation with a cathode under a high voltage. 
     The radiation image detector  5  detects radiation emitted from the radiation source  12  of the radiation radiographing device  10  and transmitted through the subject  9 , and acquires a radiation image. The radiation image detector  5  is disposed within the coverage of the radiation emitted from the radiation source  12  when radiographing is performed. The radiographic image detector  5  is disposed, for example, as shown in  FIG. 1 , between the subject  9  and a bed  13  on which the subject is laid. However, the position thereof is not limited thereto. For example, there may be provided below the bed a detector mounting opening (not shown) through which the radiation image detector  5  is to be mounted, and the radiation image detector  5  may be inserted into the detector mounting opening. 
     The radiation image detector  5  is a cassette-shaped flat panel detector. A structure of the radiation image detector  5  will be described below with reference to  FIGS. 2 and 3 . 
     As shown in  FIG. 2 , the radiation image detector  5  includes a casing  14  to protect the inside of the detector, and is configured to be portable as a cassette. 
     Inside the casing  14 , there is formed a layered imaging panel  15  to convert irradiated radiation into an electric signal. On a surface-to-be-irradiated of the imaging panel  15 , there is provided a light-emitting layer (not shown) to emit light in accordance with intensity of the radiation which is incident thereon. 
     The light-emitting layer is one generally called a scintillator layer, and, for example, contains phosphor as a main component and outputs an electromagnetic wave with a wavelength of 300 to 800 nm according to the incident radiation, namely, an electromagnetic wave (light) ranging from ultraviolet light to infrared light including visible light in the midst. 
     For the phosphor to be used in the light-emitting layer, for example, phosphor containing CaWO.sub.4 or the like as a basic substance and phosphor formed by actively imparting a main light-emitting substance into a basic substance such as CsI:Tl, Gd.sub.2O.sub.2S:Tb, and ZnS:Ag may be used. Moreover, phosphor represented by a general formula (Gd, M, Eu).sub.2O.sub.3 where M is a rare-earth element can be used. Particularly, CsI:Tl and Gd.sub.2O.sub.2S:Tb are preferable because of high radiation absorption and light-emitting efficiencies thereof. By using these substances, a low-noise and high-quality image can be obtained. 
     On the surface opposite to the surface-to-be-irradiated of the light-emitting layer, there is formed a signal detection unit  232  which converts the electromagnetic wave (light) output from the light-emitting layer into electric energy and accumulates the electric energy therein. The signal detection unit  232  further outputs an image signal based on the accumulated electric energy. 
     A circuit configuration of the imaging panel  15  will now be described.  FIG. 4  is an equivalent circuit diagram for one pixel of a photoelectric conversion unit constituting the signal detection unit  232 . 
     As shown in  FIG. 4 , one pixel of the photoelectric conversion unit includes a photodiode  233 , and a thin-film transistor (hereinafter, “TFT”)  234  that extracts electric energy accumulated in the photodiode  233  as an electric signal by switching. The extracted electric signal is amplified by an amplifier  238  to such a level that a signal reading circuit  237  can detect the electric signal. A reset circuit (not shown) including a TFT  234  and a capacitor is connected to the amplifier  238 . The reset circuit performs a reset operation for resetting the accumulated electric signal by switching on the TFT  234 . The photodiode  233  may be a photodiode simply having a parasitic capacitance, or may include an additional capacitor in parallel in order to improve dynamic ranges of the photodiode  233  and the photoelectric conversion unit. 
       FIG. 5  is an equivalent circuit diagram in which the above-described photoelectric conversion units are arranged two-dimensionally. Between the pixels, scan lines Ll and signal lines Lr are arranged to be perpendicular to each other. A TFT  234  is connected to each photodiode  233  described above, and one end of the photodiode  233  on a side to which the TFT  234  is connected is connected to the signal line Lr. The other end of the photodiode  233  is connected to one end of the adjacent photodiode  233  arranged on each row, and connected to a bias power supply  239  through a common bias line Lb. One end of the bias power supply  239  is connected to a control unit  27 , and thus a voltage is applied to the photodiodes  233  through the bias line Lb according to an instruction from the control unit  27 . The TFTs  234 , arranged on each row, are connected to their common scan line L 1 , and each scan line L 1  is connected to the control unit  27  through a scan drive circuit  236 . Similarly, the photodiodes  233  arranged on each column are connected to their common signal line Lr, and connected to the signal reading circuit  237  controlled by the control unit  27 . In the signal reading circuit  237 , an amplifier  238 , a sample/hold circuit  240 , an analog multiplexer  241  and an A/D converter  242  are arranged on the common signal line Lr in this order when viewed from the imaging panel  15 . 
     The TFT  234  may be of an inorganic semiconductor series or one using an organic semiconductor, which is used in a liquid crystal display and the like. 
     Although the photodiodes  233  are used as the photoelectric conversion elements in this embodiment, solid-state imaging elements other than the photodiodes may be used as the photoelectric conversion elements. 
     As shown in  FIG. 2 , on side portions of the signal detection unit  232 , there are disposed the scan drive circuit  16  to scan and drive the respective photoelectric conversion elements by sending pulses to the photoelectric conversion elements, and the signal reading circuit  17  to read the electric energy accumulated in the respective photoelectric conversion elements. 
     As shown in  FIGS. 2 and 3 , the radiation image detector  5  includes an image storing unit  18  which is, for example, a rewritable memory such as a RAM (random access memory) or a flash memory. The image storing unit  18  stores image signals output from the imaging panel  15 . The image storing unit  18  may be a built-in memory or a detachable memory such as a memory card. 
     The radiation image detector  5  is provided with a power supply  19  as a power supply source for supplying power to a plurality of drive units (e.g., scan drive circuit  16 , signal reading circuit  17 , communication unit  24  (described later), image storing unit  18 , battery remaining power detecting section  40  (described later), indicator  25  (described later), input operation unit  26  (described later), imaging panel  15 , etc.) constituting the radiation image detector  5 . The power supply  19  includes an auxiliary battery  20  and a chargeable battery  21 . The auxiliary battery  20  includes, e.g., manganese battery, alkaline battery, alkaline button battery, lithium battery, silver oxide battery, air-zinc battery, nickel-cadmium battery, mercury battery and lead battery. The chargeable battery  21  includes, e.g., nickel-cadmium battery, nickel-hydrogen battery, lithium-ion battery, small sealed lead battery, lead-acid battery, fuel cell, and solar cell. By providing the auxiliary battery  20  other than the chargeable battery  21 , it becomes possible to supply power to the radiation image detector  5  at least at minimum power when the charged amount of the battery  21  is insufficient or during replacement of the battery  21 . This auxiliary function prevents the detector  5  from erroneously deleting the image data stored in the image storage unit  18 , and from getting unable to receive a signal from an external device such as the console  6 . 
     On one end of the casing  14 , there are provided a connection terminal  22  for charging. For example, as shown in  FIG. 1 , by attaching the radiation image detector  5  onto a charging device  23  such as a cradle, the terminal  22  of the casing is coupled to a terminal (not shown) on the charging device  23 , and the chargeable battery  21  is charged. The chargeable battery  21  is mounted removable from the side of the casing  14  for replacement. The shape of the auxiliary battery  20  and the chargeable battery  21 , included in the power supply  19 , are not limited to that illustrated in  FIG. 2 . For example, a battery formed in a plate shape may be provided in parallel to the imaging panel  15 . By forming each battery into such a shape, a ratio of the imaging panel surface to the casing  14  is increased and thus an effective imaging area can be increased. With this shape, whole size of the radiation image detector  5  can be made smaller relative to the same imaging area, and resultantly, the radiation image detector  5  can be made thinner. 
     Further, the radiation image detector  5  is provided with a communication unit  24  (see  FIG. 3 ) for transmitting and receiving various signals to and from an external device such as the console  6 . The communication unit  24 , for example, transmits an image signal output from the imaging panel  15  to the console  6 , and receives an radiographing instruction signal, a standby instruction signal, etc. sent from the console  6  or the like. 
     Moreover, at one end on the surface of the casing  14 , an indicator (notifying unit)  25  is provided for displaying and notifying the charging state of the chargeable battery  21 , various operation states and the like, so that an operator can visually confirm the charging state of the chargeable battery  21  and the like of the radiation image detector  5 . 
     On the outer side of the casing  14 , there is provided the input operation unit  26  for inputting the radiographing instruction and the standby instruction. The radiation image detector  5  has as operation states an imaging ready state and an imaging standby state in which the power consumption is less than that of the imaging ready state, and these states can be switched with the input operation unit  26  operated. For example, when the radiographing instruction is input to the input operation unit  26  or when an radiographing instruction signal is input from the console  6  to the communication unit  24 , the imaging ready state is set. On the other hand, when the standby instruction is input to the input operation unit  26  or when a standby instruction signal is input from the console  6  to the communication unit  24 , the imaging standby state is set. Thus, the input operation unit  26  and the communication unit  24  serve as a switching unit for switching the imaging ready state and the imaging standby state according to the invention. 
     Hereinafter, the imaging ready state and the imaging standby state will be described. 
     The imaging ready state is a state in which all units, included in the radiation image detector  5  and used in a series of radiographing operations, work, that is, power is supplied to all units used in the series of radiographing operations, such as scan drive circuit  16 , signal reading circuit  17 , photodiodes  233 , TFTs  234 , image storing unit  18 , and communication unit  24 . In this state, it is possible to perform respective operations of the series of radiographing operations, such as initialization of image data, accumulation of electric energy generated according to the irradiated radiation, reading of electric signals, and transmission of image signals. In the initialization, the reset operation and a offset image reading operation in the imaging panel  15  are performed. The series of radiographing operations mean respective operations such as initialization of image data, accumulation of electric energy generated depending on the irradiated radiation, reading of electric signals, and transmission of image signals. 
     In this embodiment, the imaging standby state includes a first imaging standby mode in which power consumption is less than that of the imaging ready state, and a second imaging standby mode in which power consumption is less than that of the first imaging standby mode. 
     The first imaging standby mode is the imaging standby state in which all units used in the series of radiographing operations are active except the signal reading circuit  17  so as to go into the imaging ready state rapidly, and which is ready to perform radiographing. Specifically, it is the state in which power is supplied to respective units such as scan drive circuit  16 , photodiodes  233 , TFTs  234 , image storing unit  18 , and communication unit  24 . The second imaging standby mode is the imaging standby state in which only the image storing unit  18 , associated with storing of images, and the communication unit  24 , associated with transmission of image data to the outside and reception of signals from the outside, are active, and which is not ready to perform radiographing and in a state of very low power consumption. 
     As shown in  FIG. 3 , the radiation image detector  5  includes a control device  28  provided with the control unit (hereinafter, simply “controller”)  27  having, for example, a general-purpose CPU, ROM, RAM and the like (none of them are shown). The controller  27  reads out a predetermined program stored in the ROM to develop the program in a work area of the RAM, and enables the CPU to execute various kinds of processing according to the program. 
     The ROM stores various kinds of control data in addition to the programs. The control data include, for example, remaining power determining data for determining whether the remaining power of the chargeable battery  21  satisfies the power possible to radiographto radiograph. 
     The radiation image detector  5  further includes a battery remaining power detecting section  40  for detecting the remaining power of the chargeable battery  21 . The battery remaining power detecting section  40  detects the remaining power of the chargeable battery  21  with control of the controller  27 , and outputs the obtained battery remaining power to the controller  27 . It is possible to employ various timings for detecting the battery remaining power, and in this embodiment, the control unit  27  controls the battery remaining power detecting unit  40  so as to detect the remaining power of the chargeable battery  21  at least when an instruction of switching from the imaging standby state to the imaging ready state (radiographing instruction) is input from the input operation unit  26  or the communication unit  24 . 
     Based on the detected result of the remaining power at the time when the imaging instruction is input from the input operation unit  26  or the communication unit  24 , the controller  27  switches between the imaging ready state and the imaging standby state. Specifically, the controller  27  compares the detected result of the remaining power at the time when the radiographing instruction is input with the remaining power determining data, and controls respective running states of the plurality of drive units to switch to the imaging ready state when the detected result of the remaining power satisfies the power possible to radiographto radiograph. On the other hand, when the detected result is less than the power possible to radiographto radiograph, the controller  27  controls respective running states of the plurality of drive units so that the detector goes into the mode of minimum power consumption, namely, the second imaging standby mode. The drive control of respective units results in control of the power consumption of the battery. 
     When the detected result of the remaining power is input to the controller  27  from the battery remaining power detecting section  40 , the controller indicates the remaining power of the chargeable battery  21  on the indicator  25  based on the detected result. At this time, when the detected result of the remaining power is less than the power possible to radiographto radiograph, the controller  27  controls the indicator  25  to display that radiographing is not permitted. The controller  27  further transmits a signal indicating the state to the console  6  through the communication unit  24 . 
     The information input from the input operation unit  26  and the signal received from the communication unit  24  are sent to the controller  27 , and the controller  27  controls the respective drive units based on the sent signals. 
     The controller unit  27  drives the scan drive circuit  16  to send the pulse signals to the respective photoelectric conversion elements, thus scanning and driving the respective photoelectric conversion elements. Then, the image signal is read by the signal reading circuit  17  which reads the electric energy accumulated in the respective photoelectric conversion elements, and the image signal thus read is sent to the controller  27 . The controller  27  enables the image storing unit  18  to store the sent image signal. The image signal stored in the image storing unit  18  is sent through the communication unit  24  to the console  6  as appropriate. 
     As shown in  FIG. 6 , the console  6  includes a control device  30  including a control unit  29  which includes, for example, a general-purpose CPU, ROM, RAM and the like (none of them are shown). The control unit  29  reads predetermined programs stored in the ROM to develop the programs in a work area of the RAM, and enables the CPU to execute various kinds of processing according to the programs. 
     Moreover, the console  6  includes an input operation unit  31  that inputs various types of instructions and the like, a display unit  32  that displays an image, various messages and the like, and a communication unit  33  that transmits and receives a signal to and from an external device such as the radiation image detector  5 . 
     The input operation unit  31  includes, for example, an operation panel, a keyboard, a mouse and the like, and outputs a depression signal sent from a depressed key on the operation panel or keyboard and an operation signal sent from the mouse, to the control unit  29  as an input signal. 
     The display unit  32  includes, for example, a CRT (cathode ray tube), an LCD (liquid crystal display) and the like, and displays various screens according to an instruction of a display signal output from the control unit  29 . 
     The communication unit  33  communicates various types of information with the radiation image detector  5  through the base station  4  using a wireless communication system such as a wireless LAN. 
     A signal input from the input operation unit  31 , a signal received from the outside through the communication unit  33  and the like are sent to the control unit  29 , which executes predetermined processing on the sent signals. For example, the radiation image data detected by the radiation image detector  5  is converted into signals and sent to the control unit  29 . The control unit  29  executes the predetermined image processing based on the signals, to thereby obtain a radiation image. Further, the control unit  29  enables the display unit  32  to display the radiation image, a thumbnail image, various types of information input from the input unit, the remaining power of the chargeable battery  21  based on the detected result from the battery remaining power detecting section  40 , the state of the radiation image detector  5  (the imaging ready state or the imaging standby state), and the like. 
     A description will now be given of an action of the radiation imaging system  1  including the radiation image detector  5  applied thereto according to the embodiment. 
     When a radiographing-reservation is not input to the radiation image detector  5 , the controller  27  of the radiation image detector  5  normally controls respective running states of the plurality of drive units for the first imaging standby mode so as to start radiographing upon receiving a reservation. 
     Thereafter, when an radiographing-reservation instruction is input to the console  6 , a radiographer selects a radiation image detector  5  to be used for the radiographing on the console  6 , and inputs the choice of detector to the input operation unit  31  of the console  6 . The input choice of detector is transmitted to the communication unit  24  of the selected detector  5  through the communication unit  33  of the console  6 , and input to the controller  27 , for example, as the radiographing instruction information. Based on the radiographing instruction information, the controller  27  controls the power consumption of the chargeable battery  21  for switching from the first radiographing standby mode to the imaging ready state; however, controls, prior to the switching, the battery remaining power detecting section  40  to detect the remaining power of the battery  21 . Moreover, when the radiographer directly operates the input operation unit  26  of the detector  5  to input the radiographing instruction, the controller  27  controls respective running states of the plurality of drive units based on the radiographing instruction to thereby control the power consumption of the battery  21  for switching from the first imaging standby mode to the imaging ready state; however, controls prior to the switching the battery remaining power detecting section  40  to detect the remaining power of the battery  21 . 
     When the detected result of the remaining power obtained by the remaining power detecting section  40  satisfies the power possible to radiographto radiograph, the controller  27  controls respective running states of the plurality of drive units to thereby control the power consumption of the battery  21  so that the detector  5  can be switched to the imaging ready state. At this time, the controller  27  outputs to the console  6  through the communication unit  24  a message that the radiographing is ready. Based on the signal input to the communication unit  33 , the console  6  controls the display unit  32  to indicate that the radiographing is permitted. 
     On the other hand, when the detected result of the remaining power obtained by the remaining power detecting section  40  is less than the power possible to radiographto radiograph, the controller  27  controls respective running states of the plurality of drive units to thereby control the power consumption of the battery  21  so that the detector  5  can go into the second imaging standby mode of the imaging standby state. At this time, the controller  27  controls the indicator  25  to indicate that the radiographing is not permitted, and outputs to the console  6  through the communication unit  24  a message that the radiographing is not permitted. Based on the signal input to the communication unit  33 , the console  6  controls the display unit  32  to indicate that the radiographing is not permitted. 
     In this case, the controller  27  outputs to the console  6  through the communication unit  24  the detected result of the remaining power detecting section  40  and the state of the radiation image detector  5  (the imaging ready state or the imaging standby state). Based on the signal input to the communication unit  33 , the console  6  controls the display unit  32  to display the remaining power of the battery  21  and the state of the radiation image detector  5 . 
     As described above, according to the embodiment, when the radiographing instruction is input to the controller  27  of the radiation image detector  5  through the input operation unit  26  or the communication unit  24 , the battery remaining power detecting section  40  detects the remaining power of the battery, which allows recognition of the remaining power of the battery prior to the radiographing. This allows determination as to whether normal radiographing is possible to be performed prior to the radiographing, resultantly allows prevention of radiographing under insufficient remaining power of the battery. The prevention of radiographing under insufficient remaining power of the battery suppresses frequency of re-radiographing, and prevents a patient from unnecessary exposure to radiation. 
     Moreover, in the case that the detected result of remaining power, in the battery remaining power detecting section  40  at the time when the radiographing instruction is input to the controller  27 , satisfies the power possible to radiographto radiograph, the radiation image detector goes into the imaging ready state, and goes into the imaging standby state in the case that the detected result is less than the power possible to radiographto radiograph. Therefore, it is securely prevented to carry out radiographing with the remaining power less than the power possible to radiographto radiograph. Moreover, when the remaining power is less than the power possible to radiographto radiograph, the indicator  25  and the console  6  notify that the radiographing is not permitted, and therefore the radiographer can carry out, e.g., replacement, charging of the battery, and the like based on the notice. 
     The imaging standby state includes a plurality of modes with respective different power consumptions (the first and second imaging standby modes), and therefore the radiation image detector can be set to the most suitable state according to, e.g., its use condition. This allows suppression of useless power consumption, and allows efficient radiographing work. 
     Moreover, in the case that the detected result of remaining power, in the battery remaining power detecting section  40  at the time when the radiographing instruction is input to the controller  27 , is less than the power possible to radiographto radiograph, the detector goes into the mode of minimum power consumption (the second imaging standby mode) out of the plurality of modes in the imaging standby state, and therefore the power consumption can be reduced as much as possible when radiographing is not permitted. 
     It is apparent that the invention is not limited to the above-described embodiment and can be modified as appropriate. 
     For example, two kinds of modes are selectable as an imaging standby state in this embodiment, but the imaging standby state is not limited to the two kinds described above. For example, there may be employed an imaging standby mode in which supplying of power is stopped only to photodiodes  233  and TFTs  234  which have a characteristic of deterioration with time when power is supplied, and another imaging standby mode in which, while supplying of power is stopped to all units except the image storing unit  18  and the communication unit  24 , the power is supplied to photodiodes  233  and TFTs  234  prior to the other units because they need longer time for turning on again when the power supply is once stopped, and further, plural kinds of modes may be selected. Moreover, the detector may have only either of the two imaging standby modes described in this embodiment as examples. 
     There is described as an example in this embodiment such that the detection of remaining power of the battery  21  by the remaining power detecting section  40  is performed prior to switching from the first imaging standby state to the imaging ready state, but alternatively the detection of remaining power may be performed right after the switching. This “right after the switching” means a state that radiographing is not performed yet after switching to the imaging ready state. 
     In this embodiment, the power supply  19  is configured to have the chargeable battery  21  in addition to the auxiliary battery  20 . However, the configuration of the power supply  19  is not limited thereto, and the power supply  19  may have a replaceable and disposable battery in addition to the auxiliary battery. 
     In order to charge the chargeable battery  21 , a charging device, such as a cradle, is used in this embodiment, but by connecting the terminal of the radiation image detector having a cord for supplying power, an external power supply may supply power to charge the battery. Moreover, the battery may be charged while it is taken out of the radiation image detector. 
     As for the switching unit that gives an instruction (switching instruction) of switching between the imaging ready state and the imaging standby state, the communication unit  24  and the input operation unit  26  of the detector  5  are used as examples in this embodiment, but there can be used as the switching unit the console  6 , a mechanical switch other than these units, an electric signal, a sensor, etc. 
     When the console  6  is used as the switching unit, there can be used as an instruction signal, for example, selection information of a patient, the information input after the radiation image detector  5  to be used for radiographing is selected, a power-ON signal, ON/OFF signals of other switches, etc. 
     When a signal from the detector  5  are used as a switching instruction, there can be used, for example, a signal from switches or sensors (acceleration sensor, contact sensor, etc), a signal generated when the detector contacts an external device such as a cradle, etc. 
     By using the server  2  or the radiation source  12  as a switching unit, a signal from these devices may be used as a switching instruction. 
     Such a case is explained as an example in this embodiment that detection of remaining power by the battery remaining power detecting section  40  is performed only when the radiographing instruction is input to the controller  27 . However, it is also possible to detect the remaining power by the battery remaining power detecting section  40  when the detection of remaining power is instructed from the input operation unit  26  or the console  6 . Moreover, it is also possible to detect the remaining power automatically at predetermined intervals when the detection of remaining power by the battery remaining power detecting section  40  has not been performed for a certain period. Moreover, when radiographing is performed continuously, the detector is always in the imaging state, and it is therefore preferable to detect the remaining power with the remaining power detecting section  40  every time of radiographing. In this case, the timing of detecting the remaining power may be before or after the radiographing. 
     In addition to the detection of remaining power of the battery  21  by the battery remaining power detecting section  40 , various operation checks may be employed. There may be employed, for example, a reading operation check for checking whether an image can be read normally, a transfer-operation check for checking whether an image can be transferred normally, a wireless operation check for checking whether a signal can be communicated normally with the console  6  or the server  2 , a memory check for checking whether the internal memory works normally, and so on. Determination data necessary for respective determinations are stored in the ROM of the control device  28  in the radiation image detector  5 . 
     Second Embodiment 
     In the first embodiment, such a case has been explained as an example that, when an radiographing instruction is input from the input operation unit  26  or the communication unit  24 , the controller  27  controls the battery remaining power detecting section  40  to detect the remaining power of the chargeable battery  21 . In a second embodiment, when an instruction for switching from the second imaging standby mode to the first imaging standby mode, that is, an instruction for switching from the imaging standby mode of less power consumption to the imaging standby mode of larger power consumption out of the plurality of imaging standby modes (a standby-state switching instruction) is input from the input operation unit  26  or the communication unit  24 , the controller  27  also controls the battery remaining power detecting section  40  to detect the remaining power of the chargeable battery  21 . In the second embodiment, elements (devices, units, or sections) which are the same as corresponding elements in the first embodiment are designated by the same reference numerals and the description thereof is omitted. 
     The photodiodes  233  and the TFTs  234  need a longer time to go into their stable states when power is supplied again after supplying of power is stopped. Therefore, when radiographing is not performed for a while, the second imaging standby mode, in which power is not supplied to the photodiodes  233  and the TFTs  234 , is set, and when radiographing will soon be performed, the first imaging standby mode, in which power is supplied to the photodiodes  233  and the TFTs  234 , is set. When the second imaging standby mode is transferred to the first imaging standby mode, it is probable that radiographing will soon be performed, and hence the remaining power of the battery  21  is detected when the standby-state switching instruction is input. 
     In this case, operation of the input operation unit  26  also allows switching to be set under the plurality of imaging standby states. For example, when the instruction of switching to the first imaging standby mode is input to the input operation unit  26 , or when the instruction signal of switching to the first imaging standby mode is input to the communication unit  24  from the console  6 , the detector goes into the first imaging standby mode. On the contrary, when the instruction of switching to the second imaging standby mode is input to the input operation unit  26 , or when the instruction signal of switching to the second imaging standby mode is input to the communication unit  24  from the console  6 , the detector goes into the second imaging standby mode. That is, the input operation unit  26  and the communication unit  24  act as a switching unit for giving an instruction of switching the plurality of imaging standby states according to the invention. 
     A description will now be given of an action of the radiation imaging system  1  including the radiation image detector  5  applied thereto according to this embodiment. 
     When a reservation of radiographing is not input to the radiation image detector  5 , the controller  27  of the radiation image detector  5  normally controls respective running states of the plurality of drive units to be in the second imaging standby mode for reducing the power consumption in the standby state. 
     Thereafter, when an radiographing-reservation instruction is input to the console  6 , a radiographer selects a radiation image detector  5  to be used for the radiographing on the console  6 , and inputs the contents to the input operation unit  31  of the console  6 . The input contents are transmitted to the communication unit  24  of the selected detector  5  through the communication unit  33  of the console  6 , and are input to the controller  27  as the standby-state switching instruction information. Based on the standby-state switching instruction information, the controller  27  controls the power consumption of the chargeable battery  21  for switching from the second imaging standby mode to the first imaging standby mode; however, controls, prior to the switching, the battery remaining power detecting section  40  to detect the remaining power of the battery  21 . Moreover, when the radiographer directly operates the input operation unit  26  of the detector  5  to input the standby-state switching instruction, the controller  27  controls respective running states of the plurality of drive units based on the standby-state switching instruction to thereby control the power consumption of the battery  21  for switching from the second imaging standby mode to the first imaging standby mode; however, controls, prior to the switching, the battery remaining power detecting section  40  to detect the remaining power of the battery  21 . 
     When the detected result of the remaining power obtained by the remaining power detecting section  40  satisfies the power possible to radiographto radiograph, the controller  27  controls respective running states of the plurality of drive units to thereby control the power consumption of the battery  21  so that the detector  5  can be switched to the first imaging standby mode. At this time, the controller  27  outputs to the console  6  through the communication unit  24  a message that the radiographing is possible. Based on the signal input to the communication unit  33 , the console  6  controls the display unit  32  to display the message that the radiographing is possible. 
     On the other hand, when the detected result of the remaining power obtained by the remaining power detecting section  40  is less than the power possible to radiographto radiograph, the controller  27  controls respective running states of the plurality of drive units to thereby control the power consumption of the battery  21  so that the detector  5  can go into the second imaging standby mode. At this time, the controller  27  controls the indicator  25  to indicate that the radiographing is not permitted, and outputs to the console  6  through the communication unit  24  a message that the radiographing is not permitted. Based on the signal input to the communication unit  33 , the console  6  controls the display unit  32  to display the message that the radiographing is not permitted. 
     As described above, according to this embodiment, when the standby-state switching instruction is input to the controller  27  of the radiation image detector  5  through the input operation unit  26  or the communication unit  24 , the battery remaining power detecting section  40  detects the remaining power of the battery, and therefore the remaining power of the battery can be recognized prior to the radiographing. This allows determination as to whether normal radiographing is possible to be performed prior to the radiographing, therefore allows prevention of radiographing under insufficient remaining power of the battery. The prevention of radiographing under insufficient remaining power of the battery suppresses frequency of re-radiographing, and prevents a patient from unnecessary exposure to radiation. 
     Moreover, in the case that the detected result of remaining power of the battery remaining power detecting section  40 , at the time when the standby-switching instruction is input to the controller  27 , satisfies the power possible to radiographto radiograph, the detector goes into the first imaging standby mode, and goes into the second imaging standby mode in the case that the detected result is less than the power possible to radiographto radiograph. Therefore, it is securely prevented to carry out radiographing with the remaining power less than the power possible to radiographto radiograph. Moreover, when the remaining power is less than the power possible to radiographto radiograph, the indicator  25  and the console  6  notify that the radiographing is not permitted, and therefore the radiographer can carry out, e.g., replacement, charging or the like of the battery based on the notice. 
     In the case that the detected result of remaining power of the battery remaining power detecting section  40 , at the time when the standby-switching instruction is input to the controller  27 , is less than the power possible to radiographto radiograph, the detector is in the state of minimum power consumption (the second imaging standby mode) out of the plurality of the imaging standby states, and therefore the power consumption can be reduced as much as possible when radiographing is not permitted. 
     It is apparent that the invention is not limited to the above-described embodiment and can be modified as appropriate. 
     As for the switching unit that gives a standby-state switching instruction, the communication unit  24  and the input operation unit  26  of the detector  5  are used as examples in this embodiment, but there can be used as the switching unit a mechanical switch other than these units, an electric signal, a sensor, etc. 
     Such a case has been explained as an example in this embodiment that, when the radiation image detector  5  to be used for radiographing is input to the input operation unit  31  of the console  6 , the input contents are treated as standby-state switching instruction information, but the standby-state switching instruction information is not limited to this case, and other signals input to the console  6  may be treated as the standby-state switching instruction information. For example, there can be used selection information of a patient, the information input after the radiation image detector  5  to be used for radiographing is selected, a power-ON signal, ON/OFF signals of other switches, etc. 
     Other than these signals, a signal from the detector  5 , the server  2  or the radiation source  12  may be used as the standby-state switching instruction information. 
     When a signal from the radiation image detector  5  is used as the standby-state switching instruction information, there can be used, for example, a signal from switches or sensors (acceleration sensor, contact sensor, etc), a signal generated when the detector contacts an external device such as a cradle. 
     Third Embodiment 
     Such a case is explained in the first embodiment that the remaining power of the battery is detected by the battery remaining power detecting section  40 , and in harmonization with this, in a third embodiment, a description will be given of a case that the check unit checks drive units as to whether the drive units can perform respective operations normally at the time when the detector starts working. In the third embodiment, elements (devices, units, or sections) which are the same as corresponding elements in the first embodiment are designated by the same reference numerals and the description thereof is omitted. 
     As shown in  FIG. 7 , on the casing  14  of a radiation image detector  5 A according to the third embodiment, a start switch  41  is mounted for turning ON/OFF a main power source of the radiation image detector  5  and for inputting a start instruction and a start-halt instruction of the radiation image detector  5 . By operating the start switch  41  and the input operation unit  26 , the operation state of the radiation image detector  5  can be set for switching. The start switch  41  is used, for example, when the battery of the detector  5  is replaced, and thus used by very few frequencies. Therefore, it is preferable to mount the start switch inside a door at a position difficult to be touched such that the door is, for example, provided so as to be opened or closed at a part of the casing  14  and the switch is operable with the door opened. Such arrangement of the start switch  41  prevents the operator from erroneously touching the switch and causing occurrence of malfunction of the radiation image detector  5 . 
     In the third embodiment, the radiation image detector  5 A is shown as an example such that the power supply  19  includes only a chargeable battery. 
     The operation state of the radiation image detector  5  will now be explained. 
     The operation state of the radiation image detector  5  includes an OFF state and ON state of the main power source. In the OFF state of the main power source, power is completely turned off in all drive units of the detector  5 , and the power supply from the chargeable battery is completely shut off. On the contrary, In the ON state of the main power source, the power from the battery is supplied to respective drive units of the detector  5 , and the detector includes the imaging ready state in which radiographing operation can be performed and the imaging standby state in which power consumption is less than that of the imaging ready state. 
     As for switching of the aforementioned operation states of the radiation image detector  5 , the detector is configured to be switched to the ON state of the main power source when the start instruction is input with operation of the start switch  41 , and switched to the OFF state of the main power source when the start-halt instruction is input. The switching of respective operation states included in the ON state of the main power source is performed based on the instruction input to the input operation unit  26  or the communication unit  24 , that is, when the radiographing instruction or standby instruction is input with operation of the input operation unit  26 , or when the radiographing instruction signal or standby instruction signal is input to the communication unit  24 . 
     Specifically, when the start instruction is input with operation of the start switch  41  in the OFF state of the main power source, the detector is configured to be switched to a predetermined imaging standby state from the OFF state of the main power source. When the radiographing instruction is input to the input operation unit  26  or the radiographing instruction signal is input to the communication unit  24  from the console  6  in the first imaging standby mode of the imaging standby state, the detector is configured to be switched to the imaging ready state from the first imaging standby mode. When the standby instruction is input to the input operation unit  26  or the standby instruction signal is input to the communication unit  24  from the console  6  in the first imaging standby mode, the detector may be configured to be switched to the second imaging standby mode from the first imaging standby mode. 
     Thus, switching of operation states in the radiation image detector  5  is performed based on the instruction from the start switch  41 , the input operation unit  26  or the communication unit  24 . In the operation states according to the invention, the start switch  41  is the switching unit for giving the instruction of switching between the ON state and OFF state of the main power source, and the input operation unit  26  or the communication unit  24  is the switching unit for giving the instruction of switching between the imaging ready state and the imaging standby state. Alternatively, the switching from the ON state to the OFF state of the main power source may be also performed based on the instruction from the communication unit  24 . 
     The radiation image detector  5  has a check unit for checking whether operations of respective drive units can be performed normally. The operation check in this embodiment includes power check for the power supply  19 , communication check for the communication unit  24  and memory check for the image storing unit  18 , and the check unit include respective check operations. Each check unit will be explained below. 
     A check unit for the power check may correspond to the battery remaining power detecting section  40  shown in  FIG. 8 . The remaining power detecting section  40  detects the remaining power of the battery as the remaining power of the power supply  19  according to control of the controller  27 , checks whether the obtained remaining power is not less than the predetermined power possible to radiographto radiograph, and outputs the obtained result to the controller  27 . 
     There is provided with a communication check unit  20  as a check unit for the communication check. The communication check unit  20  checks according to control of the controller  27  whether the detector can transmit and receive signals to and from the console  6  or the server  2  normally, or can transmit an image normally, and outputs the obtained result to the controller  27 . 
     There is provided with a memory check unit  21  as a check unit for the memory check. The memory check unit  21  checks according to control of the controller  27  whether the internal memory can work normally, and outputs the obtained result to the controller  27 . 
     As for timing of the operation check by these check units, various timings are possible to be employed, but in this embodiment, the check is performed at the time of starting operation. When the start switch  41  inputs the instruction of switching from the OFF state to the ON state of the main power source (start instruction) to the controller  27 , the controller  27  controls the operation check unit to perform respective operation checks. 
     When the start instruction is input by the start switch  41 , the controller  27  detects respective check unit, and switches between the OFF state and the ON state of the main power source based on the result of operation checks of respective check units. At this time, when each drive unit for the check to be performed is once operated, the check unit performs operation check in this state, and after the operation check, the drive unit is switched to a predetermined operation state. When the check unit detects that the drive unit for the check to be performed cannot work normally, the controller  27  does not permit the detector at least to be switched to the imaging ready state. Particularly, when detected that the power supply  19  cannot work normally, the detector goes into the OFF state of the main power source, and when detected that the communication unit  24  and the image storing unit  18  cannot work normally, the detector is preferably configured to go into the second imaging standby mode. Here, the case of detection that the power supply  19  cannot work normally means that the battery remaining power detecting section  40  detects that the remaining power of the battery is less than the predetermined power possible to radiographto radiograph. 
     Specifically, when the start instruction is input, the controller  27  compares the results of power check, communication check and memory check with respective determination data stored in the ROM. When the remaining power of the battery is not less than the predetermined power possible to radiographto radiograph and the communication unit  24  and the image storing unit  18  are detected to work normally, the controller  27  enables the power supply to start supplying power from the battery so that the detector can go into the first imaging standby mode capable of radiographing immediately out of the imaging standby state, and controls the power supplied to respective drive units to thereby control the running state of the plurality of drive units. When the remaining power of the battery is not less than the predetermined power possible to radiograph and the communication unit  24  or the image storing unit  18  is detected not to work normally, the controller  27  enables the power supply to start supplying power from the battery so that the detector can go into the imaging standby mode of minimum power consumption out of the imaging standby state, namely, the second imaging standby mode, and controls the power supplied to respective drive units to thereby control the running state of the plurality of drive units. When the controller  27  detects that the remaining power of the battery is less than the predetermined power possible to radiograph, the controller shuts off the power supply to respective drive units, the power supplied from the battery at the time of operation checks, to thereby control the running state of the plurality of drive units. Accordingly, by controlling the running state of the plurality of drive units, overall power consumption of the radiation image detector  5  is controlled. 
     Moreover, the controller  27  enables the indicator  25  to display the result of operation checks performed by respective check units. Specifically, when remaining power of the battery is not less than the power possible to radiograph and the results of communication check and memory check are normal, the controller  27  controls the indicator  25  to display that the radiographing is permitted. When remaining power of the battery is not less than the power possible to radiograph and the result of either communication check or memory check is not normal, the controller  27  controls the indicator  25  to display that operation is unable to be performed normally. Further, when the result of communication check is normal, the controller  27  transmits the above display signals, as information about operation states of respective drive units, to the console  6  through the communication unit  24 . 
     A description will now be given of an action of the radiation imaging system  1  including the radiation image detector  5 A according to this embodiment applied thereto. 
     Usually, when the radiation image detector  5 A is in the OFF state of the main power source, power is completely shut off in all drive units of the radiation image detector  5 A. 
     When the radiographer operates the start switch and the radiation image detector  5 A is switched to the ON state of the main power source, the controller  27  controls the running states of respective drive units to switch from the OFF state of the main power source to a predetermined imaging standby state. Prior to the switching, the remaining power detecting section  40 , the communication check unit  20  and the memory check unit  21  are controlled to perform detection of remaining power of the battery, communication check of the communication unit  24 , and memory check of the image storing unit  18 . 
     When the controller  27  detects that the remaining power of the battery is not less than the predetermined power possible to radiograph and the communication unit  24  and the image storing unit  18  work normally, the controller  27  controls the power supplied to respective drive units from the battery so that the detector can be switched to the first imaging standby mode, to thereby control the running states of respective drive units. At this time, the controller  27  controls the indicator  25  to display a message that the radiographing is possible, and transmits to the console  6  through the communication unit  24  the message that the radiographing is possible, then based on the signal input to the communication unit  33 , the console  6  controls the display unit  32  to display the message that the radiographing is possible. 
     On the other hand, when the controller  27  detects that the remaining power of the battery is not less than the predetermined power possible to radiograph and the communication unit  24  or the image storing unit  18  cannot work normally, the controller  27  controls the power supplied to respective drive units from the battery so that the detector can be switched to the second imaging standby mode, to thereby control the running states of respective drive units. At this time, the controller  27  controls the indicator  25  to display a message that one of the communication unit  24  and the image storing unit  18 , which is detected unable to work normally, cannot work normally. When the controller  27  detects that the remaining power of the battery is not less than the predetermined power possible to radiograph and the image storing unit  18  cannot work normally, the controller  27  transmits to the console  6  through the communication unit  24  the message that the image storing unit  18  cannot work normally. Based on the signal input to the communication unit  33 , the console  6  controls the display unit  32  to display the message that the image storing unit  18  cannot work normally. Watching the indicator  25  or the display unit  32 , the radiographer, e.g., repairs the drive unit displayed unable to work normally to solve the malfunction, thereafter uses the detector again for radiographing. 
     When the controller  27  detects that the remaining power of the battery is less than the predetermined power possible to radiograph, the controller shuts off the power supply from the battery to respective drive units so that the detector goes into the OFF state of the main power source, to thereby control respective drive units. Watching that the radiation image detector  5 A does not start operating, the radiographer, e.g., mounts the radiation image detector  5  onto the charging device  23  for charging or replaces the battery to solve the malfunction of the power supply  19 , thereafter uses the detector again for radiographing. 
     Thereafter, the controller  27  of the detector  5 A, which is switched into the first imaging standby mode, detects through the input operation unit  26  or the communication unit  24  whether either the radiographing instruction information or the standby instruction information is input. 
     At this time, when radiographing-reservation instruction information is input to the console  6 , the radiographer selects a radiation image detector  5 A to be used for the radiographing on the console  6 , and inputs the contents to the input operation unit  31  of the console  6 . The input contents are transmitted to the communication unit  24  of the selected detector  5 A through the communication unit  33  of the console  6 , and are input to the controller  27  as the radiographing instruction information. Alternatively, when the radiographer directly operates the input operation unit  26  of the detector  5 A to be used for radiographing after the input of the radiographing-reservation instruction, the radiographing instruction is also input as the radiographing instruction information. Based on the radiographing instruction information, the controller  27  controls respective running states of the plurality of drive units to thereby switch from the first imaging standby mode to the imaging ready state, and then imaging operation is performed. 
     On the other hand, if the radiographer selects a radiation image detector  5 A to be switched to the second standby mode on the console  6  and inputs the contents to the input operation unit  31  of the console  6  before the radiographing-reservation instruction information is input to the console  6 , then the input contents are transmitted to the communication unit  24  of the selected detector  5 A through the communication unit  33  of the console  6 , and are input to the controller  27  as the imaging standby instruction information. Alternatively, when the radiographer directly operates the input operation unit  26  of the detector  5 A to be switched to the second standby mode before the radiographing-reservation instruction is input to the console  6 , the standby instruction is also input as the standby instruction information. The controller  27  controls respective running states of the plurality of drive units based on the standby instruction information, to thereby switch from the first radiographing standby mode to the second radiographing standby mode. 
     As described above, according to this embodiment, when the start instruction is input to the controller  27  of the radiation image detector  5 A through the start switch  41 , the check unit for the battery, communication unit  24  and image storing unit  18  check whether the units can operate normally when the detector starts operating. Therefore, it is determined prior to radiographing whether the radiographing can be performed normally. This prevents the radiographing from being performed with units malfunctioning. This can therefore suppress the frequency of re-radiographing due to malfunction of units, and can prevent a patient from unnecessary exposure to radiation. 
     The controller  27  controls operation states of respective drive units according to the result of operation checks, and when determined that any drive unit cannot work normally according to the result of operation checks, the controller  27  does not switch the radiation image detector  5 A at least to the imaging ready state. Particularly, when the remaining power of the battery is less than the predetermined power possible to radiograph, the controller causes the radiation image detector  5 A to go into the OFF state of the main power source, and it is therefore securely prevented that radiographing is performed with the battery malfunctioning. 
     Moreover, the indicator  25  and the console  6  notify that the radiographing is permitted when the remaining power of the battery, at the time when the start instruction is input to the controller  27 , is not less than the predetermined power possible to radiograph and the results of operation check of the communication check unit  20  and the memory check unit  21  are respectively normal, and notify that the detector cannot work normally when the remaining power of the battery is not less than the predetermined power possible to radiograph and the results of operation check for the communication check unit  20  and the memory check unit  21  are not normal. Based on the notification, the radiographer can deal with the corresponding malfunction of drive units. 
     Moreover, the imaging standby state includes a plurality of modes with respective different power consumptions (the first and second imaging standby modes), and therefore the radiation image detector can be set to the most suitable state according to, e.g., its use condition. This allows suppression of useless power consumption, and allows efficient radiographing work. 
     Particularly, when the remaining power of the battery, at the time when the start instruction is input to the controller  27 , is not less than the predetermined power and the result of operation checks of other units is not normal, the detector is in the mode of minimum power consumption (the second imaging standby mode) out of the plurality of modes in the imaging standby state, and therefore the power consumption can be reduced as much as possible when the battery has little remaining power. 
     It is preferable that the radiation image detector  5 A is used as a cordless system, because the cordless system improves flexibility of radiographing operation and resultantly improves overall operability compared with the case that the detector is used as a wired system having a cord or the like connected thereto. Particularly, a wireless communication system allows speedy transmission/reception of information such as images at the time of communication. At this time, the cordless radiation image detector cannot always perform the communication check and the charging check because the detector does not always communicate with the console, being different from the wired system. Accordingly, application of the present invention allows achieving a greater effect. 
     It is apparent that the invention is not limited to the above-described third embodiment and can be modified as appropriate. 
     For example, there are provided as check units with the battery remaining power detecting section  40 , the communication check unit  20  and the memory check unit  21  for performing respective operation checks of drive units in this embodiment, but various operation checks may be performed in other drive units. In this case, one check unit may be configured to perform a plurality of operation checks. 
     As a specific operation check, there may be employed a read operation check of the signal reading circuit  17  for checking whether an image can be read normally. There may be also an operation check for checking whether photodiodes  233  and TFTs  234  function normally. 
     In this case, the radiation image detector  5 A may be controlled not to be switched at least to the imaging ready state when the controller  27  determines that these drive units cannot work normally. When any abnormality is found in the radiation image detector  5 A, the detector may be restarted. Incidentally, determination data necessary for determining respective operation checks may be stored in the ROM of the control device  28  in the radiation image detector  5 A. 
     As for the switching unit that gives an instruction of switching operation states during the ON state of the main power source in the radiation image detector  5 A, the communication unit  24  and the input operation unit  26  of the detector  5 A are used as examples in this embodiment, but a sensor arranged in the radiation image detector  5 A can be used as the switching unit. The sensor may include, e.g., an acceleration sensor and a contact sensor. With these sensors, the operation states during the ON state of the main power source in the detector  5 A may be switched by detecting the change of acceleration and a pressure of the detector  5 A given when the radiation image detector  5 A gets in contact or non-contact with an external device such as a cradle. 
     The operation states during the ON state of the main power source in the radiation image detector  5 A is switched by selecting and inputting a radiation image detector  5 A to be used for radiographing to the input operation unit  31  of the console  6 . At this time, a patient to be imaged may be selected simultaneously. Alternatively, turning on the console  6  may switch the operation states during the ON state of the main power source for the radiation image detector  5 A that has been registered in the console  6  in advance. 
     Moreover, input to the controller  27  is not limited to the input from the radiation image detector  5 A or the console  6 , and may be that from other external devices provided on the network  7 , such as a host computer controlling the console  6 , and the radiation source  12 . 
     In this embodiment, when the start instruction is input to the controller  27 , that is, after starting, operation checks by the battery remaining power detecting section  40 , the communication check unit  20  and the memory check unit  21  have been performed before the detector is switched to a predetermined operation state, but these operation checks may be appropriately performed during the start operation after the detector is once switched to the predetermined operation state. In this case, as the timing of performing operation checks, for example, operation checks by the check unit can be performed when the operation check is instructed from the input operation unit  26  or the console  6 . Furthermore, when the operation checks are not performed by the check unit for a certain period during the start operation after the detector is switched to the predetermined operation state, the operation checks may be performed automatically at predetermined intervals. In case of continuous radiographing, the detector is always in an imaging state, and therefore the operation checks may be performed by the check unit preferably every time radiographing is carried out. In this case, the operation checks may be performed before or after the radiographing. 
     In this embodiment, a radiation image detected at the radiation image detector  5 A is sent to the console  6  and image processing is executed, but the destination for the radiation image to be sent to and the place of executing image processing may be other external devices such as a host computer and the server  2 . 
     Moreover, in this embodiment, the display unit  32  of the console  6  is enabled to display the result of operation checks and also function as a notifying unit, but the display unit  32  may be further enabled to display the running state of the radiation image detector  5 . 
     EXPLANATION OF REFERENCE NUMERAL 
     
         
         
           
               1  radiation imaging system 
               2  server 
               3  radiographing operation device 
               4  base station 
               5  radiation image detector 
               6  console 
               7  network 
               10  radiation imaging device 
               16  scan drive circuit 
               17  signal reading circuit 
               18  image storing unit 
               19  power supply 
               20  auxiliary battery 
               21  chargeable battery (battery) 
               23  charging device 
               24  communication unit 
               26  input operation unit 
               27  control unit 
               40  battery remaining power detecting section