WO2010109539A1 - Appareil de capture d'image - Google Patents

Appareil de capture d'image Download PDF

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Publication number
WO2010109539A1
WO2010109539A1 PCT/JP2009/001388 JP2009001388W WO2010109539A1 WO 2010109539 A1 WO2010109539 A1 WO 2010109539A1 JP 2009001388 W JP2009001388 W JP 2009001388W WO 2010109539 A1 WO2010109539 A1 WO 2010109539A1
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WO
WIPO (PCT)
Prior art keywords
approximate expression
conversion layer
dark signal
temperature
signal amount
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PCT/JP2009/001388
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English (en)
Japanese (ja)
Inventor
田邊晃一
徳田敏
貝野正知
岸原弘之
吉牟田利典
Original Assignee
株式会社島津製作所
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Priority to PCT/JP2009/001388 priority Critical patent/WO2010109539A1/fr
Publication of WO2010109539A1 publication Critical patent/WO2010109539A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
    • H04N25/60—Noise processing, e.g. detecting, correcting, reducing or removing noise
    • H04N25/63—Noise processing, e.g. detecting, correcting, reducing or removing noise applied to dark current
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
    • H04N25/30—Circuitry of solid-state image sensors [SSIS]; Control thereof for transforming X-rays into image signals

Definitions

  • the present invention relates to an imaging device used in the medical field, the industrial field, and the nuclear field.
  • the imaging apparatus includes an X-ray sensitive X-ray conversion layer, and the X-ray conversion layer converts into carriers (charge information) by the incidence of X-rays.
  • a CdTe film is used as the X-ray conversion layer.
  • the imaging apparatus includes a circuit that accumulates and reads out carriers converted by the X-ray conversion layer.
  • this circuit is composed of a plurality of gate lines G and data lines D arranged two-dimensionally, and turns on a capacitor Ca that accumulates carriers and a carrier accumulated in the capacitor Ca.
  • Thin film transistors (TFTs) Tr that are read out by switching between / OFF are arranged in a two-dimensional manner.
  • the gate line G controls ON / OFF switching of each thin film transistor Tr and is electrically connected to the gate of each thin film transistor Tr.
  • the data line D is electrically connected to the reading side of the thin film transistor Tr.
  • Each detection element is constituted by each capacitor Ca, each thin film transistor Tr, and the like.
  • the detection element electrically connected to the selected gate line G is driven to generate a carrier. Is read out.
  • dark current exists even when X-rays are not irradiated, and the dark current at the time of non-irradiation is read as a dark signal (also referred to as “dark current signal”).
  • dark current signal there is a method of reading out and measuring a dark signal regardless of the temperature of the X-ray conversion layer and subtracting the dark signal amount (see, for example, Patent Document 1). JP 2006-305228 A
  • the present invention has been made in view of such circumstances, and an object of the present invention is to provide an imaging apparatus capable of imaging without depending on the temperature of the conversion layer.
  • an imaging device includes a conversion layer that converts light or radiation information into charge information upon incidence of light or radiation, and a storage / readout circuit that stores and reads out charge information converted by the conversion layer.
  • An image pickup device that obtains an image based on charge information read by the storage / readout circuit, and can obtain a dark signal amount equivalent to a charge when light or radiation is not irradiated and the dark signal amount.
  • Approximate expression calculating means for obtaining an approximate expression of the correlation between the dark signal amount and the temperature of the conversion layer in correspondence with the temperature of the conversion layer at the time, and the approximate expression obtained by the approximate expression calculating means has been simplified Approximate expression converting means for converting into an equation, temperature measuring means for measuring the temperature of the conversion layer, an approximate expression converted into a simplified expression obtained by the approximate expression converting means, and measured by the temperature measuring means.
  • the A dark signal amount calculating means for obtaining the dark signal amount using the temperature of the conversion layer, and a correcting means for correcting charge information at the time of irradiation based on the dark signal amount obtained by the dark signal amount calculating means. are provided.
  • the dark signal amount equivalent to the charge when not irradiated with light or radiation changes according to the temperature of the conversion layer
  • the dark signal amount is acquired in advance.
  • the approximate expression calculating means obtains an approximate expression of the correlation between the dark signal amount and the temperature of the conversion layer by associating the dark signal amount with the temperature of the conversion layer when the dark signal amount is obtained.
  • the approximate expression conversion means simplified the approximate expression obtained by the approximate expression calculation means. Convert to an expression.
  • the dark signal amount calculation means obtains the dark signal amount
  • the dark signal The correction unit corrects the charge information at the time of irradiation based on the dark signal amount obtained by the amount calculation unit, and performs imaging to obtain an image based on the corrected charge information. Therefore, imaging can be performed using the approximate expression without depending on the temperature of the conversion layer. Moreover, since the approximate expression is used, it is not necessary to know all the temperatures in the corresponding range. In summary, it is not necessary to know all the temperatures in the corresponding range, and imaging can be performed using the approximate expression without depending on the temperature of the conversion layer.
  • the approximate expression conversion means preferably converts the approximate expression into a simplified expression when image acquisition is not being performed. Since the approximate expression is converted to a simplified expression using the free time when image acquisition is not performed, another processing is performed when the calculation burden during image acquisition (ie during imaging) is heavy. Without performing the above, the approximate expression is converted into a simplified expression when the calculation burden when the image acquisition is not performed is small.
  • the approximate expression conversion means may convert the approximate expression into a simplified expression for a part of the image.
  • the approximate expression calculating means obtains an approximate expression of the correlation between the dark signal amount and the temperature of the conversion layer
  • the approximate expression converting means simplifies the approximate expression obtained by the approximate expression calculating means.
  • the dark signal amount calculating means uses the approximate expression converted to the simplified expression and converted to the simplified expression by the approximate expression converting means, and the temperature of the conversion layer measured by the temperature measuring means, and the dark signal amount calculating means
  • the correction unit corrects the charge information at the time of irradiation based on the dark signal amount obtained by the dark signal amount calculation unit, and performs imaging to obtain an image based on the corrected charge information. As a result, it is not necessary to know all the temperatures in the corresponding range, and imaging can be performed using the approximate expression without depending on the temperature of the conversion layer.
  • FIG. 1 is a schematic block diagram of an X-ray imaging apparatus according to an embodiment.
  • 1 is a schematic cross-sectional view around an X-ray conversion layer of an X-ray imaging apparatus.
  • 2 is a peripheral circuit diagram of a charge-voltage conversion amplifier and an A / D converter of an X-ray imaging apparatus.
  • FIG. It is the graph which showed typically the approximate expression of the correlation of the dark signal amount and the temperature of a X-ray conversion layer.
  • FIG. 5 is a graph in which an expression obtained by simplifying the approximate expression is written in the graph of FIG. 4.
  • FIG. 5 is a graph in which an equation obtained by updating a parameter for each temperature and simplifying an approximate expression is also shown in the graph of FIG. 4.
  • It is a schematic block diagram of the conventional X-ray imaging apparatus.
  • FIG. 1 is a schematic block diagram of the X-ray imaging apparatus according to the embodiment
  • FIG. 2 is a schematic cross-sectional view around the X-ray conversion layer of the X-ray imaging apparatus
  • FIG. 3 is a charge of the X-ray imaging apparatus. It is a peripheral circuit diagram of a voltage conversion amplifier and an A / D converter.
  • X-rays will be described as an example of incident radiation
  • an X-ray imaging apparatus will be described as an example of an imaging apparatus.
  • the X-ray imaging apparatus performs imaging by irradiating a subject with X-rays. Specifically, an X-ray image transmitted through the subject is projected onto an X-ray conversion layer (CdTe film in this embodiment), and carriers (charge information) proportional to the density of the image are generated in the layer. Is converted into a carrier.
  • X-ray conversion layer CdTe film in this embodiment
  • the X-ray imaging apparatus accumulates and reads out carriers converted by a gate drive circuit 1 that selects a gate line G, which will be described later, and an X-ray conversion layer 23 (see FIG. 2).
  • a detection element circuit 2 that detects X-rays
  • a charge-voltage conversion amplifier 3 that amplifies the carrier read out by the detection element circuit 2 into a voltage
  • the charge-voltage conversion amplifier 3 An A / D converter 4 for converting a voltage analog value into a digital value, and an image processing unit 5 for obtaining an image by performing signal processing on the voltage value converted into a digital value by the A / D converter 4;
  • the controller 6 that controls the circuits 1 and 2, the charge / voltage conversion amplifier 3, the A / D converter 4, the image processing unit 5, the memory unit 7 and the monitor 9 described later, and the processed image are stored.
  • Memory section 7 An input unit 8 for setting, and a monitor 9 for displaying the processed images.
  • information such as a carrier and an image is image information related to the image.
  • the X-ray conversion layer 23 corresponds to the conversion layer in the present invention
  • the detection element circuit 2 corresponds to the storage / readout circuit in the present invention.
  • the gate drive circuit 1 is electrically connected to a plurality of gate lines G.
  • a thin film transistor (TFT) Tr described later is turned on to release reading of carriers accumulated in a capacitor Ca described later, and the voltage applied to each gate line G Is stopped (the voltage is set to ⁇ 10 V), and the thin film transistor Tr is turned off to block carrier reading.
  • the thin film transistor Tr is turned off by applying a voltage to each gate line G to cut off carrier reading and stopping the voltage to each gate line G to turn on and release carrier reading. It may be configured.
  • the detection element circuit 2 includes a plurality of gate lines G and data lines D arranged in a two-dimensional manner, and switches the capacitor Ca that accumulates carriers and the carriers accumulated in the capacitor Ca to ON / OFF.
  • the thin film transistors Tr to be read out are arranged in a two-dimensional manner.
  • the gate line G controls ON / OFF switching of each thin film transistor Tr and is electrically connected to the gate of each thin film transistor Tr.
  • the data line D is electrically connected to the reading side of the thin film transistor Tr.
  • the gate line G includes 10 gate lines G1 to G10
  • the data line D includes 10 data lines D1 to D10.
  • the gate lines G1 to G10 are respectively connected to the gates of ten thin film transistors Tr arranged in parallel in the X direction in FIG. 1, and the data lines D1 to D10 are arranged in parallel in the Y direction in FIG.
  • Each of the ten thin film transistors Tr is connected to the reading side.
  • a capacitor Ca is electrically connected to the side opposite to the reading side of the thin film transistor Tr, and the number of the thin film transistor Tr and the capacitor Ca corresponds one to one.
  • the detection elements DU are patterned on the insulating substrate 21 in a two-dimensional matrix arrangement.
  • the gate lines G1 to G10 and the data lines D1 to D10 described above are wired on the surface of the insulating substrate 21 by using a thin film forming technique by various vacuum deposition methods or a pattern technique by a photolithography method, and the thin film transistor Tr and capacitor Ca, the carrier collection electrode 22, the X-ray conversion layer 23, and the voltage application electrode 24 are laminated in order.
  • the X-ray conversion layer 23 is formed of an X-ray sensitive semiconductor thick film, and in this embodiment is formed of a CdTe film.
  • the X-ray conversion layer 23 converts X-ray information into carriers as charge information by the incidence of X-rays.
  • the X-ray conversion layer 23 is not limited to CdTe as long as it is an X-ray sensitive material in which carriers are generated by the incidence of X radiation.
  • a radiation-sensitive material that generates carriers by the incidence of radiation may be used instead of the X-ray conversion layer 23. Good.
  • a photosensitive material that generates carriers by the incidence of light may be used.
  • the carrier collection electrode 22 is electrically connected to the capacitor Ca, collects the carrier converted by the X-ray conversion layer 23, and accumulates it in the capacitor Ca.
  • a large number (10 ⁇ 10 in this embodiment) of the carrier collection electrodes 22 are formed in a vertical / horizontal two-dimensional matrix arrangement.
  • the carrier collecting electrode 22, the capacitor Ca, and the thin film transistor Tr are separately formed as each detecting element DU.
  • the voltage application electrode 24 is formed over the entire surface as a common electrode of all the detection elements DU.
  • a temperature sensor 10 for measuring the temperature of the X-ray conversion layer 23 is provided.
  • the measurement result by the temperature sensor 10 is sent to the controller 6.
  • the temperature sensor 10 corresponds to the temperature measuring means in this invention.
  • the temperature sensor 10 is provided on the voltage application electrode 24 at the end portion outside the effective detection area (not shown). Specifically, the temperature sensor 10 may be embedded in the voltage application electrode 24 as shown in FIG. 2A, or the temperature sensor 10 is laminated on the voltage application electrode 24 as shown in FIG. May be. Note that the temperature sensor may be embedded in the X-ray conversion layer 23 or the temperature sensor 10 may be stacked on the X-ray conversion layer 23.
  • the charge-voltage conversion amplifier 3 includes an amplifier 31 electrically connected to each data line D (D1 to D10 in FIG. 3), and electrically connected to each data line D.
  • the amplifier 31 and the end of the data line D of the detection element circuit 2 are electrically connected to each data line D via the switching element SW.
  • the carrier read to the data line D is sent to the amplifier 31 and the amplifier capacitor 32 of the charge-voltage conversion amplifier 3 with the switching element SW turned ON.
  • the supplied carrier is amplified with the amplifier 31 and the amplifier capacitor 32 converted into a voltage, and the sample hold 33 temporarily accumulates the amplified voltage value for a predetermined time.
  • the voltage value once stored is sent to the A / D converter 4 with the switching element 34 turned ON, and the A / D converter 4 converts the analog value of the sent voltage into a digital value.
  • the image processing unit 5 performs various signal processing on the voltage value converted into a digital value by the A / D converter 4 to obtain an image.
  • the controller 6 comprehensively controls the circuits 1 and 2, the charge / voltage conversion amplifier 3, the A / D converter 4, the image processing unit 5, the memory unit 7 and the monitor 9 described later, and in this embodiment (1)
  • the detection element circuit 2 which is a readout circuit is controlled
  • the carrier that is, the dark current
  • the dark signal amount and the dark signal amount are obtained.
  • a function for obtaining an approximate expression of the correlation between the dark signal amount and the temperature of the X-ray conversion layer 23 in correspondence with the temperature of the X-ray conversion layer 23 (function for calculating the approximate expression)
  • a function for calculating the approximate expression A function for converting the approximate expression obtained in step 1 into a simplified expression (function of approximate expression conversion)
  • an approximate expression converted into an expression simplified by the function of the approximate expression conversion and measurement with the temperature sensor 10
  • the image processing unit 5 and the controller 6 are configured by a combination of a central processing unit (CPU) and a programmable logic device (FPGA).
  • the controller 6 corresponds to the approximate expression calculation means, charge information calculation means, approximate expression conversion means, and correction means in this invention.
  • the memory unit 7 writes and stores image information and the like, and the image information and the like are read from the memory unit 7 in response to a read command from the controller 6.
  • the memory unit 7 includes a storage medium represented by ROM (Read-only Memory), RAM (Random-Access Memory), and the like. Note that a RAM is used for writing image information.
  • ROM Read-only Memory
  • RAM Random-Access Memory
  • a RAM is used for writing image information.
  • ROM Read-only Memory
  • ROM Random-Access Memory
  • a ROM is used exclusively for reading the program related to the control sequence.
  • an approximate expression is obtained, the approximate expression is converted into a simplified expression, a dark signal amount is obtained, a program relating to a control sequence to be corrected is stored in the memory unit 7, and the control sequence is read by reading the program.
  • the controller 6 is made to execute.
  • the input unit 8 includes a pointing device represented by a mouse, keyboard, joystick, trackball, touch panel, or the like, or input means such as a button, switch, or lever.
  • a pointing device represented by a mouse, keyboard, joystick, trackball, touch panel, or the like
  • input means such as a button, switch, or lever.
  • a control sequence of the X-ray imaging apparatus of the present embodiment will be described. While applying a bias voltage V A of the voltage application electrode 24 to a high voltage (e.g., several 10V ⁇ number about 100 V), thereby applying X-rays to be detected.
  • a bias voltage V A of the voltage application electrode 24 to a high voltage (e.g., several 10V ⁇ number about 100 V), thereby applying X-rays to be detected.
  • a target gate line G is selected by a scanning signal (that is, a gate driving signal) for reading a signal (here, carrier) of the gate driving circuit 1.
  • a scanning signal that is, a gate driving signal
  • the scanning signal for reading signals from the gate driving circuit 1 is a signal for applying a voltage (for example, about 15 V) to the gate line G.
  • the target gate line G is selected from the gate drive circuit 1, and each thin film transistor Tr connected to the selected gate line G is selected and designated. A voltage is applied to the gate of the thin film transistor Tr selected and designated by this selection designation to turn on. Carriers accumulated from the capacitors Ca connected to the selected and designated thin film transistors Tr are read out to the data line D via the thin film transistors Tr that have been designated and designated to be turned on. That is, the detection element DU related to the selected gate line G is selected and designated, and carriers accumulated in the capacitor Ca of the selected and designated detection element DU are read out to the data line D.
  • the amplifier 31 of the charge-voltage conversion amplifier 3 connected to the data line D is reset, and the thin film transistor Tr is turned on (that is, the gate is turned on). It is read out and amplified in a state converted into a voltage by the amplifier 31 and the amplifier capacitor 32 of the charge-voltage conversion amplifier 3.
  • the address (address) designation of each detection element DU is performed based on the scanning signal for signal reading from the gate drive circuit 1 and the selection of the amplifier 31 connected to the data line D.
  • the gate line G1 is selected from the gate drive circuit 1, the detection element DU related to the selected gate line G1 is selected and specified, and the carriers accumulated in the capacitor Ca of the selected and specified detection element DU are all stored.
  • Data line D is read out simultaneously, and after sample hold, data lines D1 to D10 are converted into digital values by A / D converter 4 in this order.
  • the gate line G2 is selected from the gate drive circuit 1, and the detection element DU related to the selected gate line G2 is selected and specified in the same procedure, and is stored in the capacitor Ca of the selected detection element DU. All the data lines D are read out simultaneously, and after sample-holding, the data lines D1 to D10 are converted into digital values by the A / D converter 4 in order. Similarly, the remaining gate lines G are sequentially selected to read out a two-dimensional carrier.
  • Each read carrier is amplified in a state of being converted into a voltage by an amplifier 31 and an amplifier capacitor 32, temporarily stored in a sample hold 33, and converted from an analog value to a digital value by an A / D converter 4. Is done.
  • the image processing unit 5 Based on the voltage value converted into the digital value, the image processing unit 5 performs various signal processing to obtain a two-dimensional image.
  • the obtained two-dimensional image and image information represented by a carrier are written and stored in the memory unit 7 via the controller 6 and are read from the memory unit 7 via the controller 6 as necessary. Further, the image information is displayed on the monitor 9 via the controller 6.
  • FIG. 4 is a graph schematically showing an approximate expression of the correlation between the dark signal amount and the temperature of the X-ray conversion layer
  • FIG. 5 shows the simplified expression along with the graph of FIG.
  • FIG. 6 is a graph in which an equation obtained by updating the parameter for each temperature and simplifying the approximate expression is also shown in the graph of FIG.
  • the dark signal mainly includes an offset component of the amplifier 31 that does not depend on the temperature change of the X-ray conversion layer 23 and a conversion layer leak component that depends on the temperature change of the X-ray conversion layer 23.
  • an offset component of the amplifier 31 that does not depend on the temperature change of the X-ray conversion layer 23
  • a conversion layer leak component that depends on the temperature change of the X-ray conversion layer 23.
  • the conversion layer leak component is described for the dark signal, and correction for the conversion layer leak component is described.
  • correction regarding the offset component of the amplifier 31 that does not depend on the temperature change is already corrected by subtracting the offset component from the carrier at the time of irradiation.
  • the carrier at the time of non-irradiation is read as a dark signal to acquire the dark signal amount.
  • the dark signal at that temperature is read in correspondence with the temperature of the X-ray conversion layer 23, and the dark signal amount and the temperature of the X-ray conversion layer 23 when the dark signal amount is obtained are plotted in correspondence. To do.
  • the correlation between the dark signal amount (in this case, the conversion layer leakage component) and the temperature of the conversion layer 23 is expressed by the following equation (1). .
  • I ⁇ ⁇ exp ( ⁇ / T) ⁇ 1 ⁇ (1)
  • I is a dark signal amount (conversion layer leak component)
  • ⁇ and ⁇ are constants
  • T is a temperature [K].
  • Exp is an exponential function. The approximate expression (1) is shown by a solid line in FIG.
  • the temperature of the environment in which the apparatus is used is constantly changing, and a clinical diagnosis problem arises due to the temperature change of the dark signal amount appearing in the image. Therefore, by obtaining the approximate expression of the expression (1) as described above, measuring the actual temperature with the temperature sensor 10, and substituting the measured temperature of the X-ray conversion layer 23 into the expression (1). The actual dark signal amount is obtained, and the dark signal amount is subtracted from the carrier at the time of irradiation to correct the carrier at the time of irradiation.
  • the temperature is measured by the temperature sensor 10 and the parameters a and b are updated.
  • the temperature of the X-ray conversion layer 23 is T1, T2, and T3.
  • parameters a and b are updated by obtaining a linear approximation formula for each temperature.
  • the approximate expression (1) is illustrated by a dotted line in FIG. 6, and an expression obtained by simplifying the approximate expression at temperatures T1 to T3 is also illustrated by a solid line in FIG.
  • the parameters while taking a picture by sequentially updating the parameters of some pixels of the image instead of all the pixels for each frame.
  • the parameter may be updated for every pixel as long as the calculation is not burdened.
  • the dark signal amount equivalent to the electric charge when X-rays are not irradiated changes according to the temperature of the X-ray conversion layer 23.
  • the function of the approximate expression calculation is an approximate expression of the correlation between the dark signal amount and the temperature of the X-ray conversion layer 23 by associating the dark signal amount with the temperature of the X-ray conversion layer 23 when the dark signal amount is obtained. (In the present embodiment, the above equation (1)) is obtained.
  • the approximate expression conversion function is an approximate expression obtained by the approximate expression calculation function.
  • the dark signal amount calculation function is the dark signal amount.
  • the carrier (charge information) at the time of irradiation is corrected based on the dark signal amount obtained by the dark signal amount calculation function, and imaging is performed to obtain an image based on the corrected carrier. Therefore, imaging can be performed using the approximate expression without depending on the temperature of the X-ray conversion layer 23.
  • the approximate expression since the approximate expression is used, it is not necessary to know all the temperatures in the corresponding range. In summary, it is not necessary to know all the temperatures in the corresponding range, and imaging can be performed using the approximate expression without depending on the temperature of the X-ray conversion layer 23.
  • the approximate expression conversion function is preferably converted into a simplified expression when the image is not acquired. Since the approximate expression is converted to a simplified expression using the free time when image acquisition is not performed, another processing is performed when the calculation burden during image acquisition (ie during imaging) is heavy. Without performing the above, the approximate expression is converted into a simplified expression when the calculation burden when the image acquisition is not performed is small.
  • the approximate expression conversion means may convert the approximate expression into a simplified expression for a part of the image.
  • the present invention is not limited to the above embodiment, and can be modified as follows.
  • the X-ray imaging apparatus as shown in FIG. 1 has been described as an example.
  • the present invention is also applicable to an X-ray fluoroscopic imaging apparatus disposed on a C-type arm, for example. May be.
  • the present invention may also be applied to an X-ray CT apparatus.
  • the present invention provides a “direct conversion type” detection element circuit in which radiation represented by incident X-rays is directly converted into charge information by an X-ray conversion layer (conversion layer).
  • conversion layer X-ray conversion layer
  • an indirect conversion type detection element circuit that converts incident radiation into light by a conversion layer such as a scintillator and converts the light into charge information by a conversion layer formed of a photosensitive material The present invention may be applied.
  • the detection element circuit for detecting X-rays has been described as an example.
  • the present invention uses a radioisotope (RI) as in an ECT (Emission-Computed Tomography) apparatus.
  • the detection element circuit is not particularly limited as long as it is a detection element circuit for detecting radiation, as exemplified by a detection element circuit for detecting ⁇ -rays emitted from an administered subject.
  • the present invention is not particularly limited as long as it is an apparatus that performs imaging by incidence of radiation, as exemplified by the above-described ECT apparatus.
  • the simplified formula parameters are obtained and updated each time.
  • the parameters are obtained in advance at every 0.1 ° C., and stored in a table in which the parameters are arranged for each temperature. May be.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Transforming Light Signals Into Electric Signals (AREA)
  • Measurement Of Radiation (AREA)
  • Apparatus For Radiation Diagnosis (AREA)

Abstract

L'invention porte sur un appareil de capture d'image qui associe une quantité de signal d'obscurité, qui est équivalente à la charge pendant une période de non exposition, à une température d'une couche de conversion de rayons X (23) lorsque la quantité de signal d'obscurité est obtenue ; qui obtient une expression approchée de la corrélation entre la quantité de signal d'obscurité et la température de la couche de conversion de rayons X (23) ; et qui convertit l'expression approchée en une version simplifiée de celle-ci. L'appareil de capture d'image utilise alors la version simplifiée de l'expression approchée, et la température de la couche de conversion de rayons X (23) est déterminée par un capteur de température (10) afin d'obtenir une quantité de signal d'obscurité, puis corrige, sur la base de la quantité de signal d'obscurité obtenue, le support durant une exposition, effectuant ainsi une capture d'image sur la base du support corrigé. Étant donné que l'expression approchée est utilisée, il n'est pas nécessaire de connaître toutes les températures dans la plage pertinente, et la capture d'image peut être réalisée sans dépendre de la température de la couche de conversion de rayons X (23). En outre, étant donné que l'expression approchée a été convertie en sa version simplifiée, la charge arithmétique sur le calcul de la quantité de signal d'obscurité peut être réduite.
PCT/JP2009/001388 2009-03-27 2009-03-27 Appareil de capture d'image WO2010109539A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1013749A (ja) * 1996-06-25 1998-01-16 Nikon Corp 光電変換器の暗電流補正装置
JPH10260487A (ja) * 1997-01-14 1998-09-29 Canon Inc 放射線画像撮影装置
JPH11126894A (ja) * 1997-08-12 1999-05-11 Hewlett Packard Co <Hp> Ｃｍｏｓイメージセンサの暗電流補正方法
JP2006305228A (ja) * 2005-05-02 2006-11-09 Shimadzu Corp 放射線撮像装置およびこれに用いるオフセット補正方法
JP2007053464A (ja) * 2005-08-16 2007-03-01 Nikon Corp ダークシェーディング除去装置および撮像装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1013749A (ja) * 1996-06-25 1998-01-16 Nikon Corp 光電変換器の暗電流補正装置
JPH10260487A (ja) * 1997-01-14 1998-09-29 Canon Inc 放射線画像撮影装置
JPH11126894A (ja) * 1997-08-12 1999-05-11 Hewlett Packard Co <Hp> Ｃｍｏｓイメージセンサの暗電流補正方法
JP2006305228A (ja) * 2005-05-02 2006-11-09 Shimadzu Corp 放射線撮像装置およびこれに用いるオフセット補正方法
JP2007053464A (ja) * 2005-08-16 2007-03-01 Nikon Corp ダークシェーディング除去装置および撮像装置

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