JP2010029419A - Radiation image photographing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation image photographing system capable of suitably correcting image data in any cases of that a radiograph detector is driven by an internal feed means or it is driven by electric power supply from an external electric source. <P>SOLUTION: This system includes a battery 28 for supplying electric power to each part, an external electric supply terminal 27 for supplying electric power from an external electric source, a FPD cassette 2 which does not perform a dark readout at a readout part 45 during photographing when the electric power is supplied from the battery 28 but performs the dark readout at the readout part 45 during photographing when the electric power is supplied from the external electric source through the external electric supply terminal 27, and a console 5, and comprises an offset correcting means for performing the offset correction about the image data which is obtained from the radiation ray transmitted through a subject to at least one of the FPD cassette 2 and the console 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radiographic imaging system.

  2. Description of the Related Art In recent years, a radiation image detector that is a two-dimensionally arranged solid-state imaging device called a so-called flat panel detector (FPD) is known as a means for acquiring a medical radiation image. In such a radiation image detector, the radiation energy is directly converted into charges using a photoconductive material such as a-Se (amorphous selenium) as a radiation detection element, and the charges are arranged two-dimensionally. A direct readout method that reads out electrical signals in pixel units by switching elements for signal readout, such as TFT (Thin Film Transistor), or radiation energy is converted into light by a scintillator, and this light is arranged two-dimensionally. It is known that there is an indirect type that is converted into electric charge by a photoelectric conversion element such as a photodiode and read out as an electric signal by a TFT or the like.

  In either method, it is necessary to correct the photographed image data by performing gain correction or offset correction on the photographed image data obtained by detecting the radiation transmitted through the subject by the radiation image detector. It is known.

In order to perform gain correction and offset correction, a gain correction value and an offset correction value are necessary. However, since these correction values change with time, the radiation image detector is periodically In general, calibration is performed and the correction value is updated.
For example, it is known that a radiation detection element constituting each pixel of an FPD, a TFT that is a switch element for signal readout, and the like are easily affected by a temperature rise due to energization and the characteristics gradually change (for example, , See Patent Document 1). For this reason, unless the gain correction value and the offset correction value are appropriately updated, appropriate correction cannot be performed.

In particular, it is known that the offset correction value has a relatively short fluctuation period (that is, easily fluctuates) compared to the gain correction value, and changes greatly due to a temperature change or the like.
Therefore, in order to grasp the variation of the offset correction value over time, so-called dark reading is performed periodically without reading the radiation image detector, and the offset correction value is based on the dark reading value. Is calculated, and offset calibration for appropriately updating the offset correction value is performed.
During this calculation, in order to mitigate the influence of noise that is electrically superimposed on the dark reading signal, dark reading is performed multiple times for each radiation detection element, and the average value of the dark reading values obtained thereby is corrected for offset correction. It is common to use a value.

  By the way, in recent years, a portable radiation image detector that incorporates a battery as an internal power feeding means and is driven without a cable has been developed (see, for example, Patent Document 2).

In order to prevent battery consumption, the portable radiation image detector described above generally does not supply power to each part when it is not used for imaging (so-called sleep mode), and supplies power to each part only during use. (See, for example, Patent Document 3).
There is also known a radiation image detector capable of both driving by a battery and driving by feeding from an external power source (see, for example, Patent Document 4). In this way, when both battery-driven and external power supply drive are possible, in the radiology room with power supply facilities, use the external power supply method, It is possible to take multiple images of multiple patients continuously without worrying about the remaining battery level, and when taking images at the bedside of a patient with insufficient power supply facilities, cableless Can be used separately, and the use efficiency of the radiation image detector can be improved.

  However, when the radiation image detector is driven by a battery, there is a problem that if the dark reading for obtaining the offset correction value is performed for each imaging, the battery power is consumed each time and the charging cycle is shortened.

  Therefore, in a system using a radiographic image detector driven by a battery, an offset correction value for each radiographic image detector is stored in advance in a storage unit or the like connected to the system via a network to perform offset correction. In such a case, it has been proposed to download and use an offset correction value corresponding to each radiation image detector from the storage means or the like (see, for example, Patent Document 5).

In addition, since it is also affected by the tube of the radiation generator used for imaging, offset correction is performed in advance for each combination of a unique tube ID that identifies the tube and a detector ID that identifies the radiation image detector. When the value is stored in a storage unit or the like on the network and offset correction is performed, an offset correction value suitable for use in offset correction of the captured image is set based on the tube ID and the detector ID. It has also been proposed to extract from a storage means or the like and download and use it (see, for example, Patent Document 6).
Japanese Patent Application Laid-Open No. 11-231055 JP-A-7-140255 JP 2006-208308 A JP 2003-172783 A JP-A-11-113889 JP 2003-24317 A

  However, according to the investigation by the present inventors, in the case of a radiation image detector that can be driven by a battery at the bedside or the like and driven by a power supply from an external power source at the imaging room or the like, the battery It has been found that the manner of use differs greatly depending on whether the driving by the power supply is driven by power supply from an external power source.

That is, for example, in the case of battery-driven driving at the bedside, it is expected that there are many single shots and the shooting frequency is relatively low. As described above, in order to prevent the battery from being consumed, the sleep mode in which power is not supplied to each unit as much as possible except during imaging is performed. ing. For this reason, it is not necessary to perform correction values such as offset correction for each photographing, and the correction values may be updated at relatively long time intervals (for example, at the start of daily work).
On the other hand, in the case of driving by power feeding from an external power source in the imaging room, it is conceivable that the radiation image detector is loaded in a Bucky device or the like and continuously used for multiple imaging. Temperature changes inside the radiation image detector are also severe. For this reason, there is a possibility that appropriate correction cannot be performed if a correction value acquired in advance is used (as a result, an appropriate image cannot be obtained).

  As described above, in the case of a radiation image detector that can be driven by a battery and driven by a power supply from an external power source, radiation is applied depending on whether the driving is performed by a battery or a power supply from an external power source. Since the state of temperature change of the image detector is greatly different, the offset correction using the same correction value set in advance in any case depends on the temperature of each element such as the radiation detection element and the TFT. There is a problem that the effect and the change in characteristics are not correctly reflected, and proper correction cannot be performed.

  The present invention has been made in view of the circumstances as described above, and in any case where the radiation image detector is driven by an internal power supply means or is driven by power supply from an external power source. Another object of the present invention is to provide a radiographic imaging system capable of performing appropriate correction on image data.

In order to solve the above problems, the present invention provides:
Detection means in which a plurality of radiation detection elements are arranged two-dimensionally, reading means for reading output values of the respective radiation detection elements of the detection means, and image data based on the output values read by the reading means Communication means for transmitting to each other, internal power supply means for supplying power to each part, external power supply terminal for supplying power from an external power source, and radiation is not irradiated upon imaging when power is supplied from the internal power supply means The reading means is controlled so as to perform the dark reading in photographing when power is supplied from the external power source through the external power supply terminal without performing the dark reading for reading the output value of each radiation detection element in the state. A radiographic image detector comprising:
A console, and
At least one of the radiation image detector and the console has an offset correction value based on an output value of each radiation detection element obtained by the dark reading for image data acquired based on radiation transmitted through the subject. It is characterized in that offset correction means for performing offset correction is provided.

  According to the present invention, when power is supplied from an external power source, in each shooting, dark reading is performed before or after shooting to generate an offset correction value, and the offset correction value is used. Since offset correction is performed, appropriate offset correction can be performed using an offset correction value closest to the characteristics at the time of shooting. In addition, when power is supplied from the internal power supply means, the offset correction value is not generated for each shooting, so that the wasteful power consumption of the built-in battery is suppressed and the shooting time of the FPD cassette 2 is kept long. The effect is that it becomes possible.

  In addition, when the radiographic image detector performs imaging based on power supply from the internal power supply means, the offset correction is performed using a predetermined offset correction value, and thus a reading operation for obtaining the offset correction value is performed. This is unnecessary, and wasteful power consumption of the internal power supply means can be suppressed. This is because when the radiographic image detector performs imaging based on power supply from the internal power supply means, the radiographic image detector by energization is set to a sleep mode (power saving mode) in which power is not supplied to each unit except during imaging. This is because there is not much temperature rise inside and is relatively stable, and appropriate correction can be performed by using a predetermined offset correction value.

  Even when there are a plurality of radiological image detectors, predetermined offset correction values are stored in association with the respective radiographic image detectors. Therefore, offset correction is performed using an offset correction value suitable for each radiographic image detector. It can be carried out.

  Since the offset correction value is stored in the storage unit in association with the identification mark for identifying the radiation image detector, and this identification mark is associated with the image data and transmitted to the console, the console corresponds to the acquired image data. The offset correction value can be reliably extracted, and the offset correction can be appropriately performed.

  When dark reading is performed for radiography in the radiation image detector, the output value of each radiation detection element obtained by the dark reading is transmitted to the console in association with the image data, and the console uses the offset correction value based on this Since the offset correction is performed using the offset correction value, the offset correction can be performed using the offset correction value closest to the characteristic at the time of shooting.

  When dark reading is performed for radiographing in the radiation image detector, offset correction is performed on the radiation image detector side using an offset correction value based on the output value of each radiation detection element obtained by the dark reading. Highly accurate offset correction can be easily performed.

  Hereinafter, a preferred embodiment of a radiographic imaging system according to the present invention will be described with reference to FIGS. 1 to 7. However, embodiments to which the present invention can be applied are not limited to the illustrated examples.

FIG. 1 is a schematic diagram showing a main configuration of a radiographic imaging system according to the present embodiment.
In this embodiment, the radiographic imaging system 1 includes a portable FPD cassette 2 and a console 5 that can communicate with the FPD cassette 2.

As shown in FIG. 1, the FPD cassette 2 is provided, for example, in an imaging room R1 that performs imaging of a subject (part of an imaging target of a patient) that is a part of a patient (not shown) by irradiating radiation. Are provided in correspondence with the photographing room R1.
In the present embodiment, a case in which one radiographing room R1 is provided in the radiographic imaging system and three FPD cassettes 2 are arranged in the radiographic room R1 will be described as an example. The number of FPD cassettes 2 provided in each photographing room is not limited to the illustrated example.
Further, when there are a plurality of shooting rooms R1, the consoles 5 do not have to be provided corresponding to the respective shooting rooms R1, and even if one console 5 is associated with the plurality of shooting rooms R1. Good.

The imaging room R1 includes a bucky device 3 including a cassette holder 48 that can load and hold the FPD cassette 2, and a radiation source such as an X-ray tube that irradiates the subject (imaging target region of the patient M). A radiation generator 4 is provided. The cassette holding unit 48 is for loading the FPD cassette 2 at the time of photographing. The cassette holding unit 48 is not limited to the one provided in the bucky device 3, and may be provided, for example, in a cradle (not shown) provided with a terminal unit capable of charging a battery 28 or communicating by wire, which will be described later. .
FIG. 1 illustrates a case where one of the bucky devices 3a for standing position photography and one of the bucky devices 3b for standing position photography are provided in the photographing room R1, but in the photographing room R1. The number of the bucky devices 3 provided in is not particularly limited. Further, in the present embodiment, a configuration in which one radiation generation device 4 is provided corresponding to each Buckie device 3 is illustrated, but for example, one radiation generation device 4 is provided in the imaging room R1. One radiation generator 4 may correspond to the plurality of bucky devices 3, and may be used by appropriately moving the position or changing the radiation irradiation direction.

  In addition, since the radiographing room R1 is a room that shields radiation, and radio waves for radio communication are also cut off, the radiographing room R1 includes these when the FPD cassette 2 and an external device such as the console 5 communicate with each other. A wireless access point (base station) 6 for relaying the communication is provided.

In the present embodiment, a front room R2 is provided adjacent to the photographing room R1. In the anterior chamber R2, a radiographer, doctor, etc. (hereinafter referred to as “operator”) controls the tube voltage, tube current, irradiation field stop, etc. of the radiation generator 4 that irradiates the subject with radiation. An operation device 7 for operating the device 3 is disposed.
A control signal for controlling the radiation irradiation conditions of the radiation generating device 4 is transmitted from the console 5 to the operation device 7. The radiation irradiation conditions of the radiation generating device 4 are transmitted from the console 5 to the operating device 7. It is set according to the control signal from. Examples of radiation irradiation conditions include exposure start / end timing, radiation tube current value, radiation tube voltage value, filter type, and the like.
An exposure instruction signal for instructing radiation exposure is transmitted from the operation device 7 to the radiation generating apparatus 4, and the radiation generating apparatus 4 applies predetermined radiation according to the exposure instruction signal at a predetermined timing. It comes to irradiate with.

  The FPD cassette 2 is a cassette type (portable type) radiographic image detector that obtains radiographic image data (hereinafter simply referred to as “image data”). In the present embodiment, each FPD cassette 2 is given a cassette ID (detector ID) as a unique identification mark.

The thickness and size of the FPD cassette 2 are the same as in the case of a CR cassette (not shown), and it is preferable that the FPD cassette 2 can be used by being loaded into various bucky devices 3 installed for the CR cassette. Specifically, as in the case of the CR cassette, it is preferably configured with dimensions conforming to JIS Z 4905 (corresponding international standard is IEC 60406), which is a standard for conventional screen / film cassettes. The thickness of the FPD cassette 2 in the radiation incident direction is formed within a range of 15 mm + 1 mm to 15 mm-2 mm. By having compatibility with the CR cassette in this way, the existing equipment can be used as it is for photographing using the FPD cassette 2, which is convenient.
The FPD cassette 2 is, for example, 8 inches x 10 inches, 10 inches x 12 inches, 11 inches x 14 inches, 14 inches x 14 inches, 14 inches x 17 inches, 17 inches x 17 inches, etc. Are available, but the size is not limited to those listed here.

FIG. 2 is a perspective view of the FPD cassette 2 in the present embodiment.
As shown in FIG. 2, the FPD cassette 2 includes a housing 21 that protects the inside. FIG. 2 shows a case where the casing 21 is formed of a front member 21a and a back member 21b. However, the shape and configuration are not particularly limited. It is also possible to form a cylindrical monocoque shape.

  As shown in FIG. 2, in the present embodiment, a power switch 22 is disposed on the side surface portion of the FPD cassette 2. The power switch 22 is for switching the power of the FPD cassette 2 on and off. When the FPD cassette 2 is not used for shooting, the power consumption of the battery 28 (see FIG. 3), which will be described later, can be suppressed by turning off the power.

  Further, a lid member 47 that is opened and closed for replacement of the battery 28 built in the housing 21 is provided on the side surface portion of the FPD cassette 2, and the FPD cassette 2 is disposed on the side surface portion of the lid member 47. Is embedded with an antenna device 46 for transmitting / receiving information to / from the outside via a wireless access point 6 in a wireless manner.

In addition, the side portion is provided with an indicator 25 that is configured by, for example, an LED or the like and displays the remaining amount of charge of the battery 28 and various operation states.
As will be described later, in the present embodiment, the indicator 25 issues a warning by blinking or the like when the FPD cassette 2 is not ready for photographing.

Further, a connector portion 26 to which a cable 49 is connected from the outside is provided on the side surface of the housing 21. An external power supply terminal 27 (see FIG. 3) for supplying power to each part of the FPD cassette 2 from the outside is connected to the connector part 26. By connecting a cable 49 to the connector part 26, an external power supply terminal 27 is connected. Power can be supplied.
The battery 28 may be charged by connecting the cable 49 to the external power supply terminal 27 via the connector unit 26.
The FPD cassette 2 is provided with a communication connector (not shown) connected to the communication unit 35 (see FIG. 3), and a cable or the like (not shown) is connected to the communication connector. Thus, wired communication with the outside is performed. Although illustration is omitted, the communication connector portion is disposed, for example, on a side surface portion on the opposite side of the housing 21 provided with the antenna device 46 in FIG. The connector unit 26 may be connected to the communication unit 35, and the cable 49 may be connected to the connector unit 26 so that wired communication with the outside is performed. In this case, it is preferable to arrange the connector part 26 in the side part on the opposite side of the housing | casing 21 in which the antenna apparatus 46 was provided in FIG.

FIG. 3 is a principal block diagram showing a functional configuration of the FPD cassette 2.
As shown in FIG. 3, the FPD cassette 2 includes a cassette control unit 30 including a microcomputer having a CPU (Central Processing Unit) (not shown), a ROM (Read Only Memory), a RAM (Random Access Memory), and a flash memory. And the like, a storage unit 31, a scanning drive circuit 32, a signal readout circuit 33, a timing unit 34, a communication unit 35, an external power supply terminal 27, a battery 28, and the like.

The cassette control unit 30 reads out a predetermined program stored in the ROM, develops it in the work area of the RAM, and the CPU executes various processes according to the program.
In addition, the storage unit 31 stores various control programs, parameters, and the like for performing various processes in the FPD cassette 2 such as a live-action image data generation process and an offset correction value generation process. The storage unit 31 temporarily stores actual image data (image data based on radiation transmitted through the subject) generated by the reading unit 45 (see FIG. 4), a dark read value, an offset correction value, and the like.
In the present embodiment, the reading control unit 30 reads the output value of each photoelectric conversion element 23 of the sensor panel unit 24 to be described later by the cassette control unit 30, the storage unit 31, the scanning drive circuit 32, the signal reading circuit 33, and the like. A reading unit 45 is configured.

  The time measuring means 34 measures the elapsed time after the photographing by the FPD cassette 2 is completed. The time measuring means 34 is configured to output information on the elapsed time from the end of shooting to the cassette control unit 30.

The communication unit 35 is connected to the antenna device 46 and the communication connector unit, and is a communication unit that transmits and receives various signals to and from an external device such as the console 5 under the control of the cassette control unit 30. The communication unit 35 performs communication by a wired method when a cable or the like is connected to the communication connector unit. When the communication unit 35 is in a state where communication by a wired method is not possible, the communication unit 35 performs a wireless method via the wireless access point 6. To communicate with an external device such as the console 5.
In the present embodiment, the communication unit 35 transmits image data to the console 5 together with a cassette ID. Further, when an offset correction value, which will be described later, is generated in the FPD cassette 2, the communication unit 35 transmits the offset correction value to the console 5 together with the image data.

The FPD cassette 2 includes a battery 28 and an external power supply terminal 27 as power supply means for supplying power to each functional unit of the FPD cassette 2.
The battery 28 is an internal power supply unit that supplies power to each functional unit of the FPD cassette 2.
As the battery 28, for example, a rechargeable battery such as a nickel cadmium battery, a nickel metal hydride battery, a lithium ion battery, a small sealed lead battery, or a lead storage battery can be used. The internal power feeding means is not limited to the battery 28, and a fuel cell or the like may be applied instead of the battery 28.
The external power supply terminal 27 is connected to the connector portion 26, and external power supply means for supplying power to each part of the FPD cassette 2 from an external power supply means (not shown) when the cable 49 is connected to the connector portion 26. It is.

  In the present embodiment, the cassette control unit 30 supplies power from the battery 28 when the cable 49 is not connected to the connector unit 26, and connects the external power supply terminal 27 when the cable 49 is connected to the connector unit 26. The power supply means is switched so as to receive power supply from the outside.

A scintillator layer (not shown) configured by a scintillator that converts irradiated radiation into light is formed inside the radiation incident surface X (see FIG. 2) of the housing 21. As the scintillator layer, for example, a layer formed using a phosphor in which a luminescent center substance is activated in a matrix such as CsI: Tl, Gd ₂ O ₂ S: Tb, ZnS: Ag, or the like can be used.

A plurality of photoelectric conversion elements 23 (see FIG. 4) for converting light output from the scintillator layer into electric signals are two-dimensionally provided on the surface of the scintillator layer opposite to the surface on which radiation is incident. A sensor panel unit 24 is provided as the arranged detection means. The photoelectric conversion element 23 is, for example, a photodiode, and constitutes a radiation detection element that converts radiation transmitted through the subject into an electrical signal together with the scintillator. In addition, the structure of a radiation detection element is not limited to the structure of a photoelectric conversion element and a scintillator.
Each photoelectric conversion element 23 arranged two-dimensionally in the sensor panel unit 24 corresponds to one pixel as a minimum unit of image reading, and each photoelectric conversion element 23 has, for example, a position x in the row direction and a column direction. The position y can be specified by the position y.

The configurations of the sensor panel unit 24 and the reading unit 45 will be further described with reference to the equivalent circuit diagram of FIG.
As shown in FIG. 4, a source electrode of a TFT 41 serving as a signal reading switch element is connected to one electrode of each photoelectric conversion element 23 of the sensor panel unit 24. In addition, a bias line Lb is connected to the other electrode of each photoelectric conversion element 23, and the bias line Lb is connected to a bias power supply 36, and a bias voltage is applied to each photoelectric conversion element 23 from the bias power supply 36. It has become so.

  The gate electrode of each TFT 41 is connected to a scanning line Ll extending from the scanning drive circuit 32, and the drain electrode of each TFT 41 is connected to a signal line Lr. Each signal line Lr is connected to an amplifier circuit 37 in the signal readout circuit 33, and an output line of each amplifier circuit 37 is connected to an analog multiplexer 39 via a sample hold circuit 38. The analog multiplexer 39 is connected to an A / D converter 40, and the signal readout circuit 33 is connected to the cassette control unit 30 via the A / D converter 40. A storage unit 31 is connected to the cassette control unit 30.

  Here, the flow of electrical signals during radiographic imaging and dark reading will be described.

  In normal radiographic imaging for photographing a subject, when radiation transmitted through the subject enters the scintillator layer, light is emitted from the scintillator layer to the sensor panel unit 24, and photoelectric conversion is performed according to the amount of light irradiation. The characteristic of the element 23 changes.

  When the radiographic image capturing is completed and the actual image data is read out as an electrical signal from the radiographic image detector 1, a read voltage is applied from the scanning line Ll to the gate electrode of the TFT 41 to open the gate of each TFT 41, An electrical signal is taken out from the conversion element 23 to the signal line Lr as a signal value via the TFT 41. Then, the signal value is amplified by the amplifier circuit 37 and the like, and is sequentially output from the analog multiplexer 39 to the cassette control unit 30 via the A / D converter 40. In this way, the cassette control unit 30 associates the amplified electrical signal output from each photoelectric conversion element 23 (x, y) with the number (x, y) of each photoelectric conversion element 23 (ie, pixel). And stored in the storage unit 31 as actual image data.

  Then, by sequentially scanning the scanning lines Ll to which the read voltage is applied to the TFT 41 and performing the above-described reading process for each scanning line Ll, the electric signals are read from all the photoelectric conversion elements 23 of the sensor panel unit 24, respectively. The signal is associated with the number (x, y) of each photoelectric conversion element 23 (that is, pixel) and is sequentially stored in the storage means 31 as actual image data. In this way, in one radiographic image capturing, actual image data obtained by being detected and amplified by each photoelectric conversion element 23 is stored as data for each photoelectric conversion element 23 (that is, each pixel). Stored in the unit 31.

  On the other hand, in the dark reading, all the photoelectric conversion elements 23 of the FPD cassette 2 are once reset to release charges, and then the gates of the respective TFTs 41 are closed, and the FPD cassette 2 is left without being irradiated with radiation. .

  Then, after a predetermined time has elapsed, a read voltage is applied from the scanning line Ll to the gate electrode of the TFT 41 to open the gate of each TFT 41, and the charge accumulated in each photoelectric conversion element 23 is taken out to the signal line Lr. Then, the charges are amplified by the amplifier circuit 37 and the like, and are sequentially output from the analog multiplexer 39 to the cassette control unit 30 via the A / D converter 40. In this way, an output value (dark image data) obtained by amplifying the charge output from each photoelectric conversion element 23 in a state where radiation is not exposed is hereinafter referred to as “dark read value”. .

  The cassette control unit 30 associates each output value output from each photoelectric conversion element 23 with the number (x, y) of each pixel and stores it in the storage unit 31 as each dark read value. Further, by sequentially scanning the scanning lines Ll for applying a reading voltage to the TFT 41 and performing the above-described reading process for each scanning line Ll, dark read values are read from all the photoelectric conversion elements 23 of the sensor panel unit 24, respectively. Are stored in the storage unit 31.

  In the present embodiment, dark scanning is performed a plurality of times immediately before each shooting, that is, when a shooting start instruction signal is transmitted from the console 5. Then, a dark reading value is output from each photoelectric conversion element 23 for each dark reading, and the cassette control unit 30 calculates an average value of the plurality of dark reading values (output values). The average value is calculated for all the photoelectric conversion elements 23, and the average value is stored in the storage unit as an offset correction value. As described above, in this embodiment, the cassette control unit 30 functions as an offset correction value generation unit that calculates an offset correction value based on the output value of the photoelectric conversion element 23 obtained by dark reading.

Note that the dark reading value necessary for generating the offset correction value (that is, multiple times of dark reading) is preferably performed immediately before shooting as much as possible, but the timing (timing) for dark reading is illustrated here. It is not limited to what you did. You may make it perform dark reading immediately after imaging | photography.
In addition, it is preferable that the plurality of dark readings be performed before each shooting as much as possible. However, the dark reading may be performed every time a predetermined number of times are taken, or the dark reading is performed every predetermined time. May be.
Note that the number of times of dark reading to generate the offset correction value is not particularly specified. For example, the offset correction value may be generated by performing dark reading once. In this case, there is no need to calculate the average value of the dark reading values, and the dark reading value in the one dark reading becomes the offset correction value.
As the number of times of dark reading is increased, a stable offset correction value with less influence of noise superposition can be calculated. However, it takes time to acquire the offset correction value accordingly. In the present embodiment, an example in which the offset correction value is calculated by performing five dark readings immediately before each photographing will be described below.

  In the present embodiment, the cassette control unit 30 does not perform dark reading to read the output value of each photoelectric conversion element 23 in a state in which radiation is not irradiated during imaging when power is supplied from the battery 28 that is an internal power supply unit. When the power is supplied from the external power supply via the external power supply terminal 27, it functions as a control means for controlling the scanning drive circuit 32, the signal readout circuit 33, and the like so that dark reading is performed in photographing.

Further, the cassette control unit 30 determines whether or not photographing is possible according to the information of the elapsed time from the end of photographing transmitted from the time measuring means 34. That is, for example, when photographing is continuously performed a plurality of times while power is supplied from an external power source, the indicator 25 is blinked until a predetermined time elapses after the photographing is finished. , Warn not to perform the next shooting.
Immediately after continuous shooting is performed, the temperature of the FPD cassette 2 is higher than that before shooting. If the camera is switched to the power supply state from the battery 28 in this state, An image signal cannot be obtained. Therefore, in such a case, it is preferable to perform the next shooting after a certain time has elapsed after the shooting is finished. As to how long it will take since the end of shooting, the temperature of the FPD cassette 2 will be stable, and it will be possible to perform shooting properly. It is preferable to store it in the storage unit 31 or the like as a predetermined elapsed time for prohibiting. In this way, even when there is an elapsed time (default value) stored in advance, the time may be arbitrarily extended or shortened by an operator setting or the like.
Even if the predetermined time has not elapsed, if the image is forced to deal with an emergency patient, the image is valid. In this case, even if the power supply from the battery 28 is used, the dark correction is performed a plurality of times after the photographing, and the offset correction value is calculated.

  As shown in FIG. 5, the console 5 includes a control unit 51 including a CPU (Central Processing Unit), a storage unit 52, an input unit 53, a display unit 54, a communication unit 55, a network communication unit 56, and the like. Each part is connected by a bus 57.

The storage unit 52 includes a ROM (read only memory), a RAM (Random Access Memory), and the like (not shown).
The ROM is composed of, for example, an HDD (Hard Disk Drive), a semiconductor non-volatile memory, or the like. The ROM performs image processing such as gradation processing and frequency processing based on automatic part recognition for detecting an affected area. In addition to storing various programs such as programs for image processing, image processing parameters for adjusting image data of captured images to an image quality suitable for diagnosis (look-up table defining tone curves used for tone processing, Frequency processing emphasis degree, etc.) are stored.
The RAM forms a work area that temporarily stores various programs, input or output data, parameters, and the like that are read from the ROM and executed by the control unit 51 in various processes that are executed and controlled by the control unit 51. .
In the present embodiment, the storage unit 52 stores patient information, imaging order information, and the like. In addition, the storage unit 52 temporarily stores actual image data transmitted from the FPD cassette 2 and information incidental thereto.

The control unit 51 is a control unit of the console 5 that reads out various programs such as a system program and a processing program stored in the ROM, expands them in the RAM, and executes various processes according to the expanded programs.
The control unit 51 is a display control unit that controls display of the display unit 54 so as to display and display an image based on the photographed image data transmitted from the FPD cassette 2.

  Further, the control unit 51 functions as order information acquisition means for acquiring patient information and imaging order information of a patient providing a subject, and is generated by the acquired patient information / imaging order information and the FPD cassette 2 and transmitted to the console 5. It functions as an associating means for associating the image data. The imaging order information or the like may be input from the input unit 53 and stored in the storage unit 52 or the like, and subject information (imaging order information) registered in advance from the HIS / RIS 8 or the like is acquired. You may come to do.

Further, the control unit 51 functions as an offset correction unit that performs offset correction using the offset correction value with respect to the actual image data transmitted from the FPD cassette 2.
Specifically, when an offset correction value is transmitted from the FPD cassette 2 together with the actual image data, the control unit 51 performs offset correction using the offset correction value. When only the cassette ID is transmitted together with the actual image data from the FPD cassette 2, for example, the cassette ID is selected from the offset correction values for each FPD cassette 2 stored in the HIS / RIS connected to the network. Based on the above, an offset correction value corresponding to the FPD cassette 2 used for photographing is extracted. Then, offset correction is performed using the extracted offset correction value.

Similarly, the control unit 51 selects a gain correction value corresponding to the FPD cassette used for photographing based on the cassette ID from the gain correction values for each FPD cassette stored in the HIS / RIS. Extraction is performed, and gain correction is performed using the extracted gain correction value.
Further, the control unit 51 performs image processing such as gradation processing and frequency processing according to the imaging region on the real image data after the offset correction and gain correction, and generates definite image data for diagnosis.

  The input unit 53 includes a keyboard having character input keys, numeric input keys, various function keys, and the like, and a pointing device such as a mouse, and a key pressing signal pressed by the keyboard and an operation signal by the mouse. Are output to the control unit 51 as an input signal.

The display unit 54 includes a monitor such as a CRT (Cathode Ray Tube) or an LCD (Liquid Crystal Display), for example, and displays various screens according to instructions of display signals input from the control unit 51.
In the present embodiment, the display unit 54 displays, for example, an image that is transmitted from the FPD cassette 2 and is based on the real image data after the offset correction / gain correction.
A pressure-sensitive (resistive film pressure type) touch panel (not shown) in which transparent electrodes are arranged in a grid pattern is formed on the screen of the display unit 54, and the display unit 54 and the input unit 53 are configured integrally. It may be a touch screen. In this case, the touch panel is configured to detect the XY coordinates of the power point pressed by a finger, a touch pen, or the like as a voltage value, and output the detected position signal to the control unit 51 as an operation signal. The display unit 54 may have a higher definition than a monitor used in a general PC (Personal Computer).

  The communication unit 55 transmits / receives information to / from the FPD cassette 2 or the like via the wireless access point 6 by a wireless method or when the cable 49 is connected to the connector unit 26 of the FPD cassette 2. Information is transmitted / received to / from the computer via a cable 49 in a wired manner.

The network communication unit 56 includes a network interface or the like, and transmits / receives data to / from an external device connected to the network N via a switching hub.
In the present embodiment, the external devices connected to the network communication unit 56 of the console 5 via the network N include the HIS / RIS 8, the PACS server 9, the imager 10, and the like, but the external devices connected to the network N are It is not limited to what was illustrated here.

The HIS / RIS 8 provides the imaging order information of the subject related to imaging to the console 5. The imaging order information includes, for example, patient information such as the name of the patient providing the examination target, imaging site, imaging method, and type of the bucky device 3 used for imaging (the bucky device 3a for the supine position or the bucky device for the standing position). 3b or the like) and the like regarding shooting reservations. Note that the imaging order information is not limited to that exemplified here, but may include other information, or may be a part of the information exemplified above.
In the present embodiment, the HIS / RIS 8 is a storage unit that stores an offset correction value and a gain correction value that are predetermined for each FPD cassette 2 in association with the cassette ID of each FPD cassette 2. Note that the storage means for storing the offset correction value and the gain correction value is not limited to the HIS / RIS8.

The PACS server 9 stores the diagnostic fixed image data output from the console 5.
Further, the imager 10 records a radiation image on an image recording medium such as a film based on the confirmed image data output from the console 5 and outputs it.

  Next, the operation of the radiographic image capturing system 1 in the present embodiment will be described with reference to FIGS. 6 and 7.

  When shooting is performed, as shown in FIG. 6, a shooting start signal is first transmitted from the console 5 to the FPD cassette 2 used for shooting (step S1). When the imaging start signal is received (step S2), the FPD cassette 2 is awakened from the sleep mode (step S3) and is ready for imaging.

The cassette control unit 30 of the FPD cassette 2 determines whether or not the cable 49 or the like is connected to the connector unit 26 and is receiving power from the outside (step S4), and the cable 49 or the like is connected to the connector unit 26. When the battery 28 is not connected and power is supplied to each unit from the battery 28 (step S4: NO), the cassette control unit 30 performs an offset correction value acquisition process (that is, performs dark reading and obtains a dark reading value). It is determined that the process of obtaining and calculating the average value is not performed (step S5). On the other hand, when receiving power supply from the outside (step S4: YES), the cassette control unit 30 determines to perform an offset correction value acquisition process (step S6).
Specifically, first, all the photoelectric conversion elements of the FPD cassette 2 are once reset to release charges, then the gates of the TFTs 41 are closed, and the FPD cassette 2 is left in a state where no radiation is irradiated. Thereafter, after a lapse of a predetermined time, a read voltage is applied from the scanning line Ll to the gate electrode of the TFT 41 to open the gate of each TFT 41, the charge accumulated in each photoelectric conversion element 23 is taken out to the signal line Lr, and the charge is amplified. The signal is amplified by 37 and the like, and sequentially output from the analog multiplexer 39 to the cassette control unit 30 via the A / D converter 20. The output value (dark read value) acquired by performing such dark reading is stored in the storage unit 31 for each photoelectric conversion element 23. Then, after performing dark reading a plurality of times (5 times in the present embodiment), the cassette control unit 30 calculates an average value for each photoelectric conversion element 23 for each dark reading value stored in the storage unit 31, and An offset correction value for each photoelectric conversion element 23 is generated.

Further, the cassette control unit 30 determines whether or not a predetermined elapsed time has elapsed since the end of the previous shooting based on the time measurement result by the time measuring means 34, and if the predetermined time has not elapsed, A warning is displayed on the effect indicator 25.
Even if the predetermined time has not elapsed, if the shooting is forced, the shooting is valid.

On the other hand, a control signal for controlling the radiation irradiation conditions of the radiation generating device 4 is transmitted from the console 5 to the operating device 7, and the operating device 7 is exposed to the radiation generating device 4 based on this control signal. Send a shooting instruction signal. In addition, it is preferable that the exposure instruction | indication from the operating device 7 is an instruction | indication to perform exposure after predetermined time considering the time which FPD cassette 2 performs an offset correction value acquisition process.
The radiation generator 4 irradiates predetermined radiation at a predetermined timing in accordance with the exposure instruction signal, and imaging is performed.

  When the photographing is completed, the reading unit 45 of the FPD cassette 2 generates actual captured image data corresponding to the output value (step S7), and the generated actual captured image data is stored in the storage unit 31 (step S8). Then, when dark reading is performed and an offset correction value is generated (step S6), the generated offset correction value and its own cassette ID are attached to the photographed image data, and no offset correction value is generated (step S5). ) Attaches only its own cassette ID to the photographed image data and transmits the photographed image data to the console 5 (step S9).

  When the console 5 receives the photographed image data (step S10), the console 5 transmits a signal indicating that the photographed image data has been received to the FPD cassette 2 (step S11). When the FPD cassette 2 receives the photographed image data reception signal from the console 5 (step S12), the FPD cassette 2 deletes the photographed image data stored in the storage unit 31 (step S13).

As shown in FIG. 7, when the console 5 receives the photographed image data from the FPD cassette 2, the console 5 determines whether an offset correction value is attached to the photographed image data (step S14). When the offset value is attached to the photographed image data (step S14: YES), the control unit 51 of the console 5 performs offset correction for the photographed image data using the offset correction value (step S15). Specifically, correction based on the corresponding offset correction value is performed on the pixel corresponding to each photoelectric conversion element 23. Further, a gain correction value corresponding to the FPD cassette 2 is acquired from the HIS / RIS 8 based on the cassette ID attached to the real image data (step S16), and gain correction is performed (step S17).
On the other hand, when no offset correction value is attached to the photographed image data (step S14: NO), the control unit 51 of the console 5 starts from the HIS / RIS 8 based on the cassette ID attached to the photographed image data. An offset correction value and a gain correction value corresponding to the FPD cassette 2 are acquired (step S18), and offset correction and gain correction are performed on the photographed image data (step S19).

  Thereafter, the console 5 performs predetermined image processing on the corrected real-image data to generate diagnostic fixed image data, and stores the generated fixed image data in the PACS server 9 or the like. The confirmed image data is not limited to the case where it is directly sent to the PACS server 9. For example, the quality of DICOM images sent from various devices, such as QA (Quality Assurance) stations, is standardized, the latest patient information and examination information are shared and examined, and the contrast of the image is fine-tuned. The image may be sent to the PACS server 9 after being optimized through a workstation having an image management function for finishing the image suitable for diagnosis.

  As described above, according to the present embodiment, when power is supplied from an external power source, in principle, the FPD cassette 2 performs dark reading, performs offset correction using the dark reading value, and the battery 28 When the power supply is received from the network, an offset correction value stored in advance in a server or the like under the network N is extracted, and the offset correction is performed using the offset correction value. For this reason, the offset correction value can be appropriately obtained according to the use situation, and when power is supplied from the battery, wasteful power consumption is suppressed, and the photographing possible time of the FPD cassette 2 is reduced. It becomes possible to keep for a long time.

That is, in order to appropriately perform the offset correction, it is important to use an offset correction value that is as close as possible to the characteristics at the time of shooting. The offset correction value differs for each FPD cassette 2, and also changes depending on the shooting history of the FPD cassette 2, in other words, a temperature change or the like.
When power is supplied from an external power source, the FPD cassette 2 is often inserted into the bucky device 3 or the like, and photographing is often performed repeatedly, and it is predicted that the temperature change of the FPD cassette 2 is severe. In order to obtain an offset correction value close to the characteristics at the time of shooting, it is preferable to perform dark reading as much as possible immediately before each shooting and generate an offset correction value based on the dark reading value obtained thereby. In this regard, in this embodiment, when power is supplied from an external power source, an offset correction value is generated by performing dark reading immediately before shooting, as a general rule. Can be obtained.
On the other hand, when power is supplied from the battery 28, it is assumed that the FPD cassette 2 is used alone on the patient's bedside or the like, and the number of radiographs is not so large. There is a high possibility that it has not changed much since startup. For this reason, even if offset correction is performed using an offset correction value stored in advance in a server or the like under the network N, the offset correction value is not significantly different from the characteristics at the time of shooting. It can be carried out. In this case, the power consumption of the battery 28 can be minimized by not performing the dark reading again.

  Even when there are a plurality of FPD cassettes 2, a predetermined offset correction value is stored in association with the cassette ID of each FPD cassette 2, and the cassette ID is associated with image data and transmitted to the console 5. Therefore, the console 5 can reliably extract the offset correction value corresponding to the image data acquired from the FPD cassette 2, and can appropriately perform the offset correction.

  In this embodiment, the FPD cassette 2 is provided with a time measuring unit, and the time measuring unit 34 measures the elapsed time from the end of shooting to determine whether shooting is possible. The determination method is not limited to this. For example, the elapsed time from the end of shooting may be transmitted from the console 5 to the FPD cassette 2, and the cassette control unit 30 may determine whether shooting is possible based on this. Further, an instruction signal for prohibiting photographing is transmitted from the console 5 to the FPD cassette 2, and when the cassette control unit 30 receives this instruction signal, each part of the apparatus is controlled such as power supply so as not to shift to a photographing ready state. You may comprise. In the case of such a configuration, it is not necessary to provide time measuring means on the FPD cassette 2 side.

  Further, in the present embodiment, when the FPD cassette 2 is not in a situation where photographing is possible, the warning is performed by blinking the indicator 25. However, the warning method is not limited to this, and a warning sound or the like is used. Means for warning by voice may be provided.

  In the present embodiment, the image data generated by the reading unit 45 is stored in the storage unit 31. However, a storage unit that stores image data may be provided separately from the storage unit 31. In this case, the storage means may be a built-in memory or a removable memory such as a memory card. Further, the capacity is not particularly limited, but preferably has a capacity capable of storing a plurality of pieces of image data. By providing such a storage means, it is possible to continuously irradiate a subject with radiation, and to record and accumulate image data each time, enabling continuous shooting and moving image shooting. Become.

  In the present embodiment, when the offset correction value is generated by the FPD cassette 2, the offset correction value is transmitted to the console 5 together with the image data, and the offset correction is performed by the console 5. However, the offset correction value is generated by the FPD cassette 2. May be generated by the offset control value in the cassette control unit 30 of the FPD cassette, and the corrected image data may be transmitted to the console 5. In this case, the cassette control unit 30 functions as an offset correction unit.

  In this embodiment, when dark reading is performed with the FPD cassette 2, the cassette control unit 30 functions as an offset correction value generation unit that calculates an offset correction value by calculating an average value of dark reading values. However, the offset correction value is not limited to the case where it is generated in the cassette control unit 30. For example, when dark reading is performed with the FPD cassette 2, the dark reading value by the dark reading (for example, data obtained by adding the dark reading values for five times by five dark readings) is transmitted to the console 5 together with the actual image data. Then, the control unit 51 of the console 5 may be configured to calculate an offset correction value from the dark reading value (for example, calculate an average value of five dark reading values) and perform offset correction. In this case, the control unit 51 of the console 5 functions as an offset correction value generation unit.

  In the present embodiment, the operation device 7 is provided in the front chamber R2 and the console 5 for controlling the entire radiographic imaging system 1 is provided separately from this, but the operation is performed in each front chamber R2. It is good also as a structure provided with the console 5 instead of the apparatus 7. FIG. In this case, the console 5 controls the radiation image capturing system 1 as a whole, and appropriately controls the radiation generator 4 and the operation of the bucky device 3.

  In the present embodiment, as the imaging order information, the control unit 51 of the console 5 reads out information stored in advance in the storage unit 52, or the imaging order information registered in advance in the HIS / RIS 8 or the like is networked. However, the imaging order information does not necessarily have to be created before radiographic imaging, and imaging order information is created so as to be associated with the acquired image data after radiographic imaging. It is also possible to configure so as to.

  In the present embodiment, the configuration in which the cable 49 is directly connected to the connector portion 26 has been described as an example. However, the configuration in which the cable 49 is connected to the connector portion 26 is not limited thereto. For example, when the FPD cassette 2 is placed on a cradle or the like or loaded into the bucky device 3, the cable 49 connected to an external device or the like is connected to the connector portion 26 of the FPD cassette 2 via the cradle or the bucky device 3. It is good also as a structure indirectly connected to.

  In addition, it goes without saying that the present invention is not limited to the present embodiment and can be appropriately changed.

It is the schematic which shows the system configuration | structure of one Embodiment of the radiographic image generation system which concerns on this invention. It is a perspective view which shows the FPD cassette applied to the radiographic image generation system of FIG. It is a principal part block diagram which shows the functional structure of the FPD cassette shown in FIG. FIG. 3 is an equivalent circuit diagram illustrating configurations of a sensor panel unit, a reading unit, and the like of the FPD cassette illustrated in FIG. 2. It is a principal part block diagram which shows the functional structure of the console applied to the radiographic image generation system shown in FIG. It is a flowchart which shows operation | movement of the radiographic image generation system in 1st Embodiment. It is a flowchart which shows operation | movement of the radiographic image generation system in 1st Embodiment.

Explanation of symbols

1 Radiation image generation system 2 FPD cassette (Radiation image detector)
5 Console 7 Operation device 22 Power switch 24 Antenna device 27 External power supply terminal 28 Battery 30 Cassette control unit 35 Communication unit 51 Control unit 55 Communication unit N Network R1 Photography room R2 Front room

Claims (8)

Detection means in which a plurality of radiation detection elements are arranged two-dimensionally, reading means for reading output values of the respective radiation detection elements of the detection means, and image data based on the output values read by the reading means Communication means for transmitting to each other, internal power supply means for supplying power to each part, external power supply terminal for supplying power from an external power source, and radiation is not irradiated upon imaging when power is supplied from the internal power supply means The reading means is controlled so as to perform the dark reading in photographing when power is supplied from the external power source through the external power supply terminal without performing the dark reading for reading the output value of each radiation detection element in the state. A radiographic image detector comprising:
A console, and
At least one of the radiation image detector and the console has an offset correction value based on an output value of each radiation detection element obtained by the dark reading for image data acquired based on radiation transmitted through the subject. A radiographic imaging system characterized in that offset correction means for performing offset correction is provided.   The radiographic image detector includes an offset correction value generation unit that calculates the offset correction value based on an output value of each of the radiation detection elements obtained by the dark reading. The radiographic imaging system described. The communication unit of the radiation image detector transmits an output value of each of the radiation detection elements obtained by the dark reading in imaging in association with image data acquired based on radiation transmitted through a subject to the console. ,
2. The radiation according to claim 1, wherein the console includes an offset correction value generation unit that calculates the offset correction value based on an output value of each radiation detection element obtained by the dark reading. Image shooting system.   The offset correction unit is configured to perform offset correction using a predetermined offset correction value when the radiographic image detector performs imaging based on power supply from the internal power supply unit. The radiographic imaging system according to any one of claims 1 to 3. A plurality of the radiation image detectors capable of communicating with the console,
5. The radiographic imaging system according to claim 4, further comprising storage means for storing the predetermined offset correction value in association with each of the radiographic image detectors. Each of the plurality of radiation image detectors is given a unique identification mark,
The storage means stores an offset correction value in association with this identification mark,
The communication means of the radiological image detector transmits the identification mark in association with the image data to the console,
6. The radiation according to claim 5, wherein the console extracts an offset correction value used for offset correction from the storage unit based on the identification mark transmitted in association with the acquired image data. Image shooting system. When shooting is performed with an external power supply connected to the external power supply terminal,
The communication means of the radiation image detector transmits an output value of each radiation detection element obtained by dark reading in photographing to the console in association with image data acquired based on radiation transmitted through the subject. The radiographic imaging system according to any one of claims 1 to 6, wherein   When imaging is performed with an external power supply connected to the external power supply terminal, the offset correction means of the radiation image detector outputs the output of each radiation detection element obtained by the dark reading performed at the time of imaging. An offset correction value based on the value is used to perform offset correction of image data acquired based on radiation transmitted through the subject, and the communication means transmits the image data after offset correction to the console. The radiographic imaging system according to any one of claims 1 to 6.

Images