JP4448084B2 - Radiation detection system and method for driving radiation detection system - Google Patents

Description

  The present invention relates to a radiation detection system and a method for driving the radiation detection system, and in particular, one-dimensional or two-dimensional imaging such as an imaging device using radiation typified by visible light or X-ray, such as a still camera or a radiation imaging device. The present invention relates to a radiation detection system suitably used for an apparatus and a method for driving the radiation detection system.

  Traditionally speaking, silver halide photography using an optical camera and a silver halide film has been the majority. Although semiconductor technology has been developed, imaging devices capable of capturing moving images such as video camcorders using solid-state imaging devices using Si single crystal sensors represented by CCD sensors and MOS sensors have been developed. The image does not match the silver halide photograph in terms of the number of pixels and the S / N ratio, and the silver salt photograph is usually used to capture a still image.

  On the other hand, in recent years, there has been an increasing demand for image processing by a computer, storage by an electronic file, and transmission of an image by e-mail, and an electronic imaging device that outputs a digital signal that is inferior to a silver salt photograph image is desired. The same can be said for not only general photography but also inspection and medical fields.

  For example, X-ray photography is generally used in the medical field as a silver salt photography technique. This is a technique for irradiating an affected part of a human body with X-rays emitted from an X-ray source and determining the presence or absence of a fracture or a tumor, for example, based on the transmission information, and has been widely used for medical diagnosis for a long time. Usually, X-rays transmitted through the affected area are once incident on a phosphor, converted into visible light, and exposed to a silver salt film. However, although silver salt film has the advantages of high sensitivity and high resolution, it has the disadvantages that it takes time to develop, it takes time to store and manage, and it cannot be sent immediately to remote locations. Thus, there is a demand for an electronic X-ray imaging apparatus that outputs a digital signal that is not inferior to a silver halide photographic image. Of course, this is the same for non-destructive inspection of specimens such as structures regardless of the medical field.

  In response to this demand, an imaging apparatus using a large sensor in which imaging elements using photoelectric conversion elements of hydrogenated amorphous silicon (hereinafter referred to as a-Si) are arranged two-dimensionally has been developed. In this type of imaging apparatus, for example, a metal layer or an a-Si layer is deposited on an insulating substrate having a side of about 30 to 50 cm using a sputtering apparatus, a chemical vapor deposition apparatus (CVD apparatus), or the like. × 2000 semiconductor diodes are formed, a reverse bias electric field is applied thereto, and the thin film transistors (hereinafter referred to as TFTs) formed at the same time can individually detect charges flowing in the reverse direction of these individual diodes. It is a thing. It is widely known that when a reverse electric field is applied to a semiconductor diode, a photocurrent corresponding to the amount of light incident on the semiconductor layer flows, and this is utilized. However, even when light is not applied at all, a so-called dark current flows, which causes shot noise, which is a factor that lowers the detection capability of the entire apparatus, that is, the sensitivity called the SN ratio. This can adversely affect medical diagnosis and examination decisions. For example, it goes without saying that it is a problem if a lesion or defective part is overlooked due to this noise. Therefore, how to reduce this dark current is important.

  It is also known that when a bias is constantly applied to a semiconductor diode or other photoelectric conversion element, defects in the semiconductor are increased by a flowing current and the performance is gradually deteriorated. This appears as a phenomenon such as an increase in dark current or a decrease in current due to light, that is, photocurrent. In addition, if an electric field is continuously applied, not only the number of defects will increase, but also the movement of ions and electrolysis will cause the threshold value of the TFT and the corrosion of the metal used in the wiring, leading to a decrease in the reliability of the entire device. Sometimes. Poor reliability in the commercialization of medical and testing equipment can cause problems. For example, it should not break down during an emergency diagnosis / treatment or examination. Up to now, the sensitivity and reliability have been described by taking a semiconductor diode as an example. However, the present invention is not limited to the diode because it can be applied to various types of photoelectric conversion elements.

FIG. 7 shows an example of a schematic block diagram of the X-ray imaging apparatus. In FIG. 7, reference numeral 1 denotes a sensor portion in which a large number of photoelectric conversion elements and TFTs are formed on an insulating substrate, and an IC or the like for controlling these is mounted. The sensor section is roughly composed of a bias application terminal (Bias) for applying an electric field to the photoelectric conversion element and a start terminal (START) for giving a read / initialization start signal, and two-dimensionally arranged photoelectric conversion elements. There are three terminal portions of an output terminal (OUT) that outputs the output as a serial signal. An X-ray source 2 emits pulsed X-rays under the control of the control circuit 5. The X-rays pass through a test part of a specimen such as an affected part of a patient, and the transmitted X-rays including information go to the sensor unit 1. Although not shown between the sensor unit 1 and the specimen, there is a phosphor, and transmitted X-rays are converted into visible light. The converted visible light enters the photoelectric conversion element in the sensor unit. Reference numeral 3 denotes a power source for applying an electric field to the photoelectric conversion element, which is controlled by a control switch (SW) or a control circuit 5.
JP-A-9-131337

  However, the apparatus as described above has the following points that can be improved.

  FIG. 8 shows an example of the operation of the X-ray imaging apparatus shown in FIG. FIG. 8A to FIG. 8D are schematic timing charts showing operations in the imaging apparatus. FIG. 8A shows the operation of the imaging apparatus. FIG. 8B shows the X-ray emission timing of the X-ray source 2. FIG. 8C shows the timing of the applied bias of the photoelectric conversion element. FIG. 8D shows a current flowing through the photoelectric conversion element. FIG. 9 is a flowchart showing the flow of operation.

  In FIG. 8A, up to the arrow indicated by (SW ON), no bias is applied to the photoelectric conversion element (Bias OFF) as shown in FIG. 8C. Here, as shown in FIG. 9, <SW ON? If> 301 is detected and the control switch (SW) is turned on, [Bias ON] 302 is performed. This is also shown in FIG. At the same time, Int. , The charges of the individual photoelectric conversion elements in the sensor unit 1 are initialized as indicated by [Initialize Sensors] 303 in FIG. When the initialization is completed, the control circuit 5 controls the X-ray source 2 and emits X-rays. As a result, the imaging apparatus is exposed (Exp. In FIG. 8B and [Exposure] 304 in FIG. 9). Thereafter, as shown by Read in FIG. 8A and [Read Sensors] 305 in FIG. 9, charges including optical information flowing in the individual photoelectric conversion elements are read out by the operation of the internal TFT and IC. Thereafter, as shown in FIG. 8C or as shown by [Bias OFF] in FIG. 9, the electric field of the photoelectric conversion element is set to 0 (OFF). Then, it waits until the next control switch is turned on.

  However, in the above operation, as shown in FIG. 8D, the current of the photoelectric conversion element before and after exposure is large. A semiconductor, particularly an amorphous semiconductor such as a-Si, has a large dark current immediately after a bias is applied, and a current flows even though no light is incident for a while. This indicates that a good X-ray image may not be reproduced due to the influence of shot noise as described above. In this case, proper diagnosis or examination may not be possible. It is explained that the cause of this dark current is a place where the Fermi level in the forbidden band relatively moves due to the change of the electric field in the semiconductor, and this causes the movement of electrons and holes in the trap near the center of the forbidden band. This trap is caused by a semiconductor defect or a discontinuity of the crystal structure at the semiconductor-insulator interface, and this increase in dark current occurs in any material and photoelectric conversion element of any structure. Another reason is that an unstable current flows until charges such as ions move and stabilize immediately after the electric field is applied.

  FIG. 10 shows an example of another operation of the X-ray imaging apparatus. The block diagram of the entire apparatus is almost the same as FIG. 10, operations and expressions equivalent to those in FIG. 8 are indicated by the same symbols. Most of the operations are the same as the operations of FIG. 8 described above, but are different in that an electric field is continuously applied to the photoelectric conversion element as shown in FIG. That is, as can be seen from FIG. 11, the Bias ON state is maintained without performing [Bias ON / OFF] in a series of exposure operations. As a result, the dark current is reduced as shown in FIG. 10D as compared with the operation shown in FIG. 8, and it seems that a good image can be obtained. However, there is actually a problem hidden behind the scenes, and this operation cannot be adopted as a product. The reason is that in this operation, the hospital continuously applies an electric field to the photoelectric conversion element during a time that may be used such as within a consultation time. In the operation of FIG. 8, for example, an imaging operation is performed 100 times a day for 3 seconds per time, and a total of 300 seconds is applied to the photoelectric conversion element. On the other hand, in the operation of FIG. If a certain time is 8 hours, the operating condition is about 30000 seconds, which is about 100 times longer. This means that an electric field is applied to the photoelectric conversion element even when it is not actually operated for shooting (that is, when there is no operation). As described above, this leads to a decrease in reliability, and is not practical in consideration of maintenance costs.

  (Object of the invention) An object of the present invention is to solve this problem and to provide a photoelectric conversion device such as an imaging device having high sensitivity, high reliability, and ease of use, and a driving method of the photoelectric conversion device.

  It is another object of the present invention to provide a photoelectric conversion device that can obtain information on a high SN ratio with little noise and a driving method thereof.

  A further object of the present invention is to provide a photoelectric conversion device that can obtain image information at a desired timing and that does not need to irradiate radiation such as X-rays more than necessary, and a driving method thereof.

  In addition, the present invention provides a photoelectric conversion device and a driving method thereof capable of obtaining image information with high immediacy without using a silver salt film and capable of obtaining image information that can be inspected at a remote place. The purpose is to provide.

In order to solve the above problems, the present invention provides a pixel portion in which a plurality of pixels each having a photoelectric conversion element and a switch element connected to the photoelectric conversion element are arrayed, and for driving the photoelectric conversion element A radiation detection device comprising: a drive circuit that operates the switch element; and a wavelength converter that converts radiation from a radiation source into light having a wavelength that can be detected by the photoelectric conversion element; and a voltage with respect to the photoelectric conversion element In a radiation detection system having a power supply unit for applying a power source, and a control unit for controlling the radiation detection device and the power supply unit , the control unit uses the drive circuit to the radiation detection device, the initialization of the pixel portion during a period for stabilizing the dark current generated in the photoelectric conversion elements upon application of the voltage after starting the application of the voltage to the photoelectric conversion element Cormorant the initialization operation, a read operation for reading radiation image information from the radiation detector after irradiation, to perform the, characterized in that to perform a plurality of times the initialization operation.

Further, the present invention includes a pixel unit picture element consisting of switch elements corresponding to the photoelectric conversion element and the photoelectric conversion element is formed by a plurality arranged to operate said switching element to drive said photoelectric conversion element A radiation detector comprising: a driving circuit; a wavelength converter that converts radiation from a radiation source into light having a wavelength detectable by the photoelectric conversion element; and a power source for applying a voltage to the photoelectric conversion element And a control unit for controlling the radiation detection apparatus, wherein the power supply unit starts applying the voltage to the photoelectric conversion element after applying the voltage. said radiation by using the initializing operation for initializing the pixel portion by using the drive circuit during a period for stabilizing the dark current generated in the photoelectric conversion element, the driving circuit after irradiation Anda read operation for reading radiation image information from the detecting device, the initialization operation is characterized by being performed a plurality of times.

  According to the present invention, voltage or current is applied to the photoelectric conversion means by turning on the switch means, and after dark current has decreased, exposure can be started immediately by turning on the switch means again.

  That is, it is not necessary to always apply an electric field or the like to the photoelectric conversion means, and it is possible to obtain reliable image information with a high S / N ratio without using shot noise by using the photocurrent after the dark current is reduced. Immediately after the exposure can be started, a user-friendly imaging device can be provided.

  In combination with an X-ray source, it can provide an X-ray imaging device for medical diagnosis or nondestructive inspection that can provide digital signals with excellent reliability, sensitivity, and usability instead of silver salt film. Diagnosis of a special doctor or engineer.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic system block diagram of an imaging apparatus according to the first embodiment of the present invention. In the present embodiment, a radiation imaging apparatus for the purpose of X-ray examination (for example, X-ray diagnosis) is configured. In FIG. 1, the same parts as those in FIG.

  In FIG. 1, reference numeral 1 denotes a sensor unit in which a large number of photoelectric conversion elements (photoelectric conversion means) and TFTs are formed on an insulating substrate, and an IC or the like for controlling these is mounted. The sensor unit 1 roughly includes a bias application terminal (Bias) for applying an electric field to the photoelectric conversion element and a start terminal (START) for giving a read / initialization start signal, and each photoelectric conversion element arranged in two dimensions. In this case, there are three output terminals (OUT) that output the output as a serial signal. An X-ray source 2 emits pulsed X-rays under the control of the control circuit 4. The X-rays pass through the affected part or the examination part of a sample such as a patient or an object, and the transmitted X-rays including information go to the sensor unit 1. Although not shown between the sensor unit 1 and the patient, there is usually a wavelength converter such as a phosphor, and the transmitted X-rays are converted into a wavelength detectable by the sensor unit 1, for example, visible light, and the inside of the sensor unit 1 Incident on the photoelectric conversion element. Reference numeral 3 denotes a power source for applying an electric field to the photoelectric conversion element, which is controlled by SW1 that functions as a first switch means. The control circuit 4 is connected to SW1 and SW2 serving as the second switch means, and controls start signals of various operations given to the sensor unit 1 based on these two pieces of information and other information. At the same time, the X-ray source 2 is given a timing for emitting X-rays.

  FIG. 2A shows the appearance of SW1 and SW2. SW1 and SW2 are mounted in one grip-like case so as to be easily handled by the operator and constitute a switch box 71. In the case, two switches and springs are mounted on each switch, and both the switches SW1 and SW2 are turned off when the hands are released. In addition, SW2 is locked, and normally, when SW1 is turned on in the off state, the lock is released and it becomes movable, and it is mechanically prohibited so that SW1 is off and SW2 is not turned on. ing. In the present embodiment, this prohibition is mechanically performed, but this is performed electrically. For example, when SW2 is accidentally pressed when SW1 is off, it is invalidated and SW2 is turned on. It may be eliminated. FIG. 2A shows a state in which the hand is released, the switch lever 73 linked to SW1 and the switch lever 74 linked to SW2 are released, and both SW1 and SW2 are off. When the operator handles the switch box 71, the operator grasps the grip portion 72 and touches the SW1 switch lever 73 with the thumb. When lightly pressed with the thumb from this state, the state shown in FIG. This is because the force of the spring of the switch lever 73 is configured to be weaker than the pressing force required to press an elastic member such as the spring of the switch lever 74. In this state, SW1 is on and SW2 is off. When the button is further pressed, the state shown in FIG. 2C is entered, and both SW1 and SW2 are turned on. Thus, the switch box 71 is configured to be able to take three states, and is configured such that SW1 and SW2 are never turned on when the switch box 71 is not touched, that is, when there is no operation. Further, the force of the elastic member such as the spring of the switch lever 73 is appropriately adjusted, and it is configured so that a normal person cannot keep pushing for a minute, for example, for one minute or longer. As a result, the state where SW1 and SW2 are kept pressed for a long time is prohibited. That is, it can be regarded as no operation when the state has not changed for one minute.

  SW1 and SW2 are not limited to the mechanical switch structure described above. SW1 and SW2 may be provided independently, and the above-described operation may be achieved in an electric circuit. Further, SW1 and SW2 may be constituted by electrical switches (for example, transistors) instead of mechanical switches. For example, it is possible to configure SW1 and SW2 with one mechanical switch (SW0) and electrical switches. In this case, for example, when SW0 is pressed once, SW1 is turned on. After SW0 is released, SW2 is turned on when SW0 is pressed again, and when SW0 is released, SW1 and SW2 are turned off. It may be configured (the identification of whether SW0 is pressed once or twice may be displayed by emitting light of different luminescent colors).

Here, an example of the operation of the imaging apparatus of the present embodiment shown in FIG. 1 will be described with reference to FIG. 3A to 3D are timing charts showing the operation of the imaging apparatus, and FIG. 4 is a flowchart showing the flow of the operation. FIG. 3A shows the operation of the imaging apparatus. FIG. 3B shows the X-ray emission timing of the X-ray source 2. FIG. 3C shows the timing of the applied bias of the photoelectric conversion element. FIG. 3D shows a current flowing through a certain photoelectric conversion element. In FIG. 3A, up to the arrow indicated by (SW1 ON), as shown in FIG. 3C, an electric field, that is, a bias is not applied to the photoelectric conversion element (Bias OFF). This is because the control circuit 4 recognizes no operation and controls the power supply 3 in the stop mode (Stop MODE). In this embodiment, no operation means that SW1 is turned off, and the control circuit 4 determines this because SW1 is turned off. A broken line indicates a state in which no bias is applied. Here, as shown in FIG. 4, it is determined <SW1 ON?> 901, and if the control switch (SW1) is turned on, [Bias ON] 902 is performed . This is also shown in FIG. Sensor unit 1 in this state is the standby state as shown by the Wait or [Wait] 903 shown in FIG. 3 (A) or FIG. This state is a standby mode (Stand-by MODE). During this standby state, the dark current of the photoelectric conversion element decreases as shown in FIG. At this time, the control circuit 4 prohibits the operator from turning on the SW2 for a predetermined time until the dark current decreases. Whether the dark current has decreased or not may be detected directly, or the time required until it decreases in advance may be grasped and prohibited during that time. The prohibiting method may be mechanically prohibited or electrical. Or you may show the display of the lamp etc. which show prohibition to an operator. Even if the switch SW2 is pressed, the control circuit may not start the photographing operation. During this prohibition, the operator may prepare for imaging of a specimen such as a patient or an object. After the prohibition is released, if necessary, an instruction such as “stop breath” is given, or the operation of the object is started, and SW2 is turned on at the timing when an image is desired (Sw2 ON) 904. When SW2 is turned on, an exposure mode (Exposure MODE) is started, and Int. Alternatively, as indicated by [Initialize Sensors] 905, the charges of the individual photoelectric conversion elements in the sensor unit 1 are initialized. When the initialization is completed, the control circuit 4 controls the X-ray source 2 and emits X-rays. As a result , Exp. Alternatively, the exposure indicated by [Exposure] 906 is performed. When the exposure is completed, the imaging of the specimen is completed, and the specimen may move freely at this point. That is, it does not have to move between a and b shown in FIG. Normally, the initialization of the sensor unit 1 is completed in 30 to 300 ms, and the pulse width of the X-ray is 50 to 200 ms. After exposure, the imaging device reads out charges including light information flowing in each photoelectric conversion element by the operation of the internal TFT and IC as shown by Read or [Read Sensors] 907 in FIG. 3A or FIG. It is. Thereafter, the state of SW1 is detected at <SW1 ON?> 908 in FIG. 4 , and if SW1 is off, as shown in FIG. 3C or as shown in [Bias OFF] 909 in FIG. The electric field of the photoelectric conversion element is set to zero. And it waits until the next control switch turns on. Further, when SW1 is turned on for continuous imaging or the like, the detection of SW2 on is waited for as shown in FIG. In this way, in the case of continuous shooting, it is not necessary to wait for the second time as shown by Wait or [Wait] 903 in FIG. Further, when it is desired to interrupt the work when the SW1 is turned on during the work, the SW1 is turned off when the switch lever of the SW1 is released, and [Bias OFF] 909 is obtained as shown in FIG.

  As described above, in this embodiment, an electric field is not applied to the photoelectric conversion element when there is no operation, the dark current is reduced during exposure, and the patient is stationary only for a moment. Therefore, an imaging apparatus with high reliability, high sensitivity, and good usability is provided.

  It is needless to say that the electric field of the photoelectric conversion element does not need to be zero when no operation is performed, and it is effective to suppress the electric field as compared with various operations.

FIG. 5A to FIG. 5D and FIG. 6 are timing charts and flowcharts showing the operation of still another embodiment of the present invention. The system configuration is omitted because it is almost the same as the above-described embodiment. The difference from the above embodiment is that the configuration of the control circuit is different. Here, the description will be made with reference to FIGS. 5A to 5D and 6 with a focus on the differences from FIGS. 3A to 3D and FIG .

  In this embodiment, as can be seen from FIG. 5A or FIG. 6, the sensor unit initialization Int. Alternatively, [Initialize Sensors] 1002 is being started. In addition, initialization is started immediately after one initialization is completed, and periodic initialization, that is, continuous internal charge reset is continued. This prevents the charge in the sensor unit from accumulating due to dark current due to the standby state becoming longer than necessary. This periodic charge reset may actually be slightly different from the charge reading operation after exposure, although the accumulation time may be slightly different, but the operation sequence is almost the same, just using the obtained signal as information is there. Although the periodic charge reset operation in the sensor unit (photoelectric conversion element) is not illustrated, the state of SW1 and SW2 is detected and judged by the circuit in the control circuit 4 in FIG. 1 as shown in FIG. While being repeated periodically. In this state, when SW2 is turned on, the exposure mode is started after initialization (charge reset operation) at the point when this is detected. Further, in the present embodiment, fixed pattern noise as shown in FIG. 5A or Get FPN and [Get FPN Data] 1003 in FIG. 5A following the charge reading [Read Sensors] 907 including optical information during the exposure mode. Data reading for correction of (FPN) is performed, and subsequently, data reading for gain variation correction is performed as indicated by Get GN and [Get GAIN Data] 1004 in FIG. However, these operations are the same as the operation of the sensor unit, which is the same as the operation of reading the charges including the optical information [Read Sensors] 907, and reading the charges in the dark state (that is, the state in which X-rays are not irradiated). It only reads the charge of the reference light information. The reference light information can be obtained, for example, by irradiating and reading a light source such as an X-ray in the absence of a specimen.

  That is, the image pickup apparatus according to the present embodiment is characterized in that the sensor unit always repeats the same operation until the exposure mode ends after the standby [Wait] 903 in the standby mode ends. The fact that the movement of the sensor unit periodically performs the same movement means that the operation of each part inside the sensor unit is moving in an equilibrium state, and there is no strange transient response or the like, and a very stable SN ratio is good. Image information is obtained. In addition, it is a great effect that the control method is simplified and the circuit can be simplified. Further, even during the waiting [Wait] 903, it can actually be the same as the charge reading operation [Read Sensors] 907 after the exposure.

  In addition, since initialization [Initialize Sensors] 1002 has not started after SW2 is turned on, the time until exposure [Exposure] 906 is shortened, and on average, half of the time required for initialization is shortened. The As a result, when the specimen such as a patient must be stationary (between a and b or between a and b), the initialization of the sensor unit usually ends in 30 to 300 ms, and the X-ray pulse width is If it is 50 to 200 ms, it will be sufficient if it is stationary for about 0.3 seconds on average. This is a major feature of the present embodiment because a periodic charge reset operation, that is, an initialization operation is performed during the standby mode and it is easy to shift to the exposure mode.

  Furthermore, as shown in FIG. 6, this embodiment has a timer in the control circuit, and even if the exposure mode ends, even if SW1 is turned off for a predetermined time (5 minutes in this embodiment). [Bias OFF], that is, it is not in the sleep mode. As a result, even if the shooting is not continuous, if it is within a certain period of time, the sleep mode is not entered, and it is not necessary to wait for the next shooting. In addition, even if the switch box 71 is structured as illustrated in FIGS. 2A to 2C, the sleep mode does not occur even if the finger is released for a short time. That is, in the present embodiment, the control circuit interprets that SW1 is turned off for a short time (for example, within 5 minutes) as still working, and determines that it is not in the no-operation state. As a result, even if the shooting is not completely continuous, if the shooting is continued to some extent, the sleep mode is not set, and the standby state [Wait] 903 is not set at the next shooting. Further, the control circuit automatically enters [Bias OFF] 909, that is, the sleep mode when SW1 is off for a certain time (for example, 5 minutes or more). This further increases efficiency while maintaining high reliability and improves usability.

  In this embodiment, [READY lamp ON / OFF] 1001 and 1007 indicating preparation OK are controlled to improve usability.

It is a schematic system block diagram for demonstrating a suitable example which has a photoelectric conversion apparatus. (A) thru | or (C) are typical perspective views for demonstrating a suitable example of a switch, respectively. (A) thru | or (D) are typical timing charts for demonstrating an example of a drive and output of a photoelectric conversion apparatus. 10 is a flowchart for explaining an example of driving a photoelectric conversion device. (A) thru | or (D) are typical timing charts for demonstrating the drive and output example of a photoelectric conversion apparatus. 6 is a flowchart for explaining an example of driving of the photoelectric conversion device. It is a schematic system block diagram which has a photoelectric conversion apparatus. (A) thru | or (D) are typical timing charts for demonstrating the drive and output example of a photoelectric conversion apparatus, respectively. 10 is a flowchart for explaining an example of driving a photoelectric conversion device. (A) thru | or (D) are typical timing charts for demonstrating the drive and output example of a photoelectric conversion apparatus. 10 is a flowchart for explaining an example of driving a photoelectric conversion device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor part 2 X-ray source 3 Power supply 4 Control circuit 5 Control circuit

Claims (8)

A pixel portion in which a plurality of pixels each having a photoelectric conversion element and a switch element connected to the photoelectric conversion element are arranged; a drive circuit for operating the switch element to drive the photoelectric conversion element; and a radiation source A wavelength converter that converts radiation into light having a wavelength that can be detected by the photoelectric conversion element;
A power supply unit for applying a voltage to the photoelectric conversion element;
In the radiation detection system having the radiation detection apparatus and a control unit for controlling the power supply unit ,
The control unit stabilizes a dark current generated in the photoelectric conversion element when the voltage is applied after the voltage application to the photoelectric conversion element is started in the radiation detection apparatus using the drive circuit . radiation and initializing operation of initializing the pixel portion during a read operation for reading radiation image information from the radiation detector after irradiation, to perform the, characterized in that to perform a plurality of times the initialization operation Detection system. The radiation detection system according to claim 1, wherein the control unit causes the radiation detection apparatus to perform a standby operation before the initialization operation in the period .   3. The control unit according to claim 1, wherein the control unit causes the radiation detection apparatus to perform an operation of reading out dark output information or reference light information of the pixel unit after the readout operation. 4. Radiation detection system.   4. The control unit according to claim 1, wherein the control unit controls the pixel unit and the driving circuit to perform the same operation in the initialization operation and the readout operation. 5. Radiation detection system. A pixel unit picture element consisting of switch elements corresponding to the photoelectric conversion element and the photoelectric conversion element is formed by a plurality arranged, and a drive circuit for operating said switching element for driving the photoelectric conversion elements, the radiation source A wavelength converter that converts radiation from the light into light having a wavelength detectable by the photoelectric conversion element, a radiation detection device, a power supply unit for applying a voltage to the photoelectric conversion element, and the radiation detection A control unit for controlling the apparatus, and a method for driving the radiation detection system,
After the power supply unit starts applying the voltage to the photoelectric conversion element, the pixel unit is initialized using the driving circuit during a period for stabilizing the dark current generated in the photoelectric conversion element when the voltage is applied. Initialization operation to perform
A read operation for reading out radiation image information from the radiation detection device using the drive circuit after radiation irradiation, and
The method for driving a radiation detection system, wherein the initialization operation is performed a plurality of times during the period . The radiation detection system driving method according to claim 5, wherein a standby operation is performed before the initialization operation in the period .   The radiation detection system driving method according to claim 5, wherein an operation of reading out dark output information or reference light information of the pixel unit is performed after the readout operation.   The radiation detection system driving method according to claim 5, wherein the pixel unit and the driving circuit perform the same operation in the initialization operation and the readout operation.