JP2011101693A - Radiation image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation image forming apparatus capable of reducing the temperature drift of a read IC even when using a sleep state of turning OFF power supply to the read IC or the like in nonuse together in a portable radiation image forming apparatus. <P>SOLUTION: The radiation image forming apparatus 2 having a photographable state and the sleep state as driving states includes: a sensor panel part 24 for detecting radiation; the read IC 34 provided with a charge amplifier 37, etc., for reading an output value from the sensor panel part 24 by each pixel unit; a power supply part 27 for supplying power to respective functional parts including the read IC 34; and a power supply control part 30a for switching the ON/OFF of the power supply by the power supply part 27 and controlling the driving state of the respective function parts. When being in the sleep state or shifting from the sleep state to the photographable state, the power supply control part 30a turns ON the power supply by the power supply part 27 for supplying power to the read IC 34 and makes the read IC 34 perform a read operation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a radiation image forming apparatus.

  2. Description of the Related Art Conventionally, as a means for acquiring a medical radiographic image, a radiographic image forming apparatus in which a solid-state imaging device called a so-called flat panel detector (FPD) is two-dimensionally arranged is known. In such a radiation image forming apparatus, 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 recent years, a cassette-type radiation image forming apparatus that has a built-in battery and can be driven without a cable has been developed. When the radiation image forming apparatus is configured in this way, it is possible to perform imaging with a high degree of freedom such as portable imaging on the bedside of a patient.

In such a portable radiation image forming apparatus, there is a limitation on the driving time that comes from the storage capacity of the built-in battery, and the power source that supplies power to various circuits is locally turned on / off while not being used for imaging. By doing so, power consumption is kept low and battery consumption is prevented.
In a portable radiation image forming apparatus, there are components that consume a large amount of power, such as a control circuit and a wireless communication module. Among them, a read IC (Read Out Integrated Circuit: ROIC) that constitutes a signal read circuit is included. In particular, the number of used devices may be large, and this power consumption accounts for a large proportion of the total power consumption of the radiation image forming apparatus.

  For this reason, when shooting is not performed, power is not supplied to the signal readout circuit or the like, and a shooting pause mode (so-called sleep mode) is set. A configuration is known in which the power consumption of a battery is suppressed by making a transition to (see, for example, Patent Document 1).

JP 2006-208308 A

However, the signal readout circuit is required to output an extremely low noise in the signal conversion when converting the electric charge stored in the pixel into a voltage. However, the temperature readout of various circuits and components in the radiation image forming apparatus is required. There is a problem of being easily affected.
For this reason, it is recommended that a radiation image forming apparatus of a type called a special purpose machine that is used with an external power supply be used after preheating for a certain period of time before imaging in order to eliminate the effects of temperature drift. ing.

  In this regard, in the portable radiographic image forming apparatus, as described above, power consumption is suppressed by appropriately switching ON / OFF the power supply to the readout IC constituting the signal readout circuit. When the power supply to the IC is turned ON / OFF, the temperature drift of the read IC itself may appear in the signal output in photographing immediately after returning from the sleep mode. In this case, there is a possibility that image noise may be caused as an unexpected artifact, and a high-definition image cannot be obtained.

The temperature drift has the greatest effect when there is a difference in the temperature of the readout IC when shooting a real image and a dark image in the shooting sequence. This is because, in the image correction of the radiation image forming apparatus (FPD), as described below, the difference between the real image and the dark image is taken for each pixel.
That is, the correction data is actual image data-dark image data. Here, each image data has a temperature-dependent characteristic. When the charge amount read for each pixel is x, the temperature of the readout IC at the time of photographing is t, and the origin temperature is t0, Can be expressed as:
Pixel signal value = f (x, t) = f (x, t0) × (1 + α × t) + f (x, t0) × β (t−t0)
In the above equation, α and β are coefficients determined by the characteristics of the readout IC, and generally α is negligibly small compared to β.

Therefore, when a temperature change occurs during shooting of a real image and a dark image, a difference in signal value due to temperature drift (“temperature drift value” in the following equation) is obtained as follows. Here, for convenience of explanation, an example of signal values in a real image portion that has not been irradiated with radiation is shown.
Temperature drift value = f (0, tj) −f (0, ta) = f (0, t0) × α × (tj−ta) + f (0, t0) × β (tj−ta)
In the above equation, tj means the temperature of the readout IC at the time of capturing a real image, and ta means the temperature of the readout IC at the time of capturing a dark image.
If α is ignored in the above formula, the following formula is obtained.
Temperature drift value = f (0, t0) x β (tj−ta)
In this case, an offset proportional to the temperature fluctuation value (tj−ta) occurs. This offset value is observed as image noise (artifact) particularly in a low dose amount region when log-converted into a display image, and the image quality is deteriorated.

  The present invention has been made in view of the above circumstances, and even in a portable radiographic image forming apparatus, even when a sleep state in which power supply to a read IC or the like is turned off when not in use is used in combination. An object of the present invention is to provide a radiation image forming apparatus capable of reducing temperature drift.

In order to solve the above-described problems, a radiographic image forming apparatus of the present invention includes:
A radiographic image forming apparatus having a radiographable state capable of radiographic imaging and a sleep state in which power supply to each functional unit is turned off during non-imaging as a driving state,
A plurality of radiation detection elements constituting the pixel are arranged in a two-dimensional matrix to detect radiation; and
A readout IC that includes a charge amplifier and the like, and reads out an output value of each radiation detection element of the sensor panel unit in units of pixels;
A power supply unit for supplying power to each functional unit including the readout IC;
A control unit that controls ON / OFF of power supply by the power supply unit to control a driving state of each functional unit;
The control unit turns on the power supply by the power supply unit that supplies power to the read IC when the sleep state or the transition from the sleep state to the photographing enabled state, and performs a read operation on the read IC It is characterized by making it.

  According to the present invention, in a radiographic image forming apparatus driven by power supply from an internal power supply unit, even when a sleep state in which a power source such as a reading IC is turned off when not in use is taken in the sleep state or from the sleep state. When the state shifts to a possible state, power is supplied to the reading IC to perform the reading operation, so that the temperature of the reading IC can be kept constant and generation of image noise due to temperature drift can be reduced.

It is the schematic which shows an example of the system configuration | structure of the radiographic image forming system to which the radiographic image forming apparatus which concerns on 1st Embodiment is applied. It is a perspective view which shows the external appearance of the radiographic image forming apparatus which concerns on 1st Embodiment. FIG. 3 is an equivalent circuit diagram illustrating configurations of a sensor panel unit, a reading unit, and the like of the radiographic image forming apparatus illustrated in FIG. 2. It is a circuit diagram which shows typically the principal part structure of read-out IC. It is the block diagram which showed typically the functional structure of the radiographic image forming apparatus shown in FIG. It is explanatory drawing which shows the relationship between the drive state in 1st Embodiment, and the temperature of read-out IC. It is explanatory drawing which shows the relationship between the drive state in 2nd Embodiment, and the temperature of read-out IC.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Note that embodiments to which the present invention is applicable are not limited to this.

[First Embodiment]
First, a radiation image forming apparatus according to a first embodiment of the present invention will be described with reference to FIGS. However, the present invention is not limited to the illustrated example.

FIG. 1 is a schematic diagram illustrating a schematic configuration of a radiation image forming system to which a radiation image forming apparatus according to the present embodiment is applied.
The radiographic image forming system is a system applied in radiographic imaging performed in a hospital, and includes a radiographic image forming apparatus 2 that obtains radiographic image data (hereinafter simply referred to as “image data”), and the radiographic image forming. A console 5 capable of communicating with the device 2 is provided.
The console 5 is connected to a wireless LAN (Local Area Network) 8, and similarly to a wireless access point 113 (described later), a signal relay 116, a data management server 7 such as a PACS, etc. connected to the wireless LAN 8. It is possible to transmit and receive information in a wireless manner.

As shown in FIG. 1, the radiographic image forming apparatus 2 is provided in an imaging room R1 that performs imaging of a subject (an imaging target site of the patient H), for example, by irradiating radiation. The console 5 is provided corresponding to the photographing room R1.
In the present embodiment, a case where one imaging room R1 is provided in the image processing system and one radiation image forming apparatus 2 is arranged in the imaging room R1 will be described as an example. The number of rooms and the number of radiation image forming apparatuses 2 provided in each imaging room are 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.

In the radiographing room R1, a bucky device 110 having a cassette holding unit 111 capable of loading and holding the radiographic image forming apparatus 2, and a radiation source such as an X-ray tube that irradiates a subject (imaging target region of the patient H) A radiation generator 112 is provided which comprises (not shown). The cassette holding unit 111 is for loading the radiation image forming apparatus 2 at the time of imaging.
Although FIG. 1 illustrates the case where one bucky device 110 for standing-up shooting is provided in the shooting room R1, the number and types of the bucky devices 110 provided in the shooting room R1 are particularly limited. It is not limited. For example, the bucky device 110 may be a bucky device for standing position shooting, or may be provided with a bucky device for standing position shooting and a bucky device for position shooting. Further, when there are a plurality of the bucky devices 110, one radiation generation device 112 may be provided corresponding to each of the bucky devices 110, or one radiation generation device 112 is provided in the imaging room R1, One radiation generation device 112 may correspond to the plurality of bucky devices 110, 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 blocked, the radiographic image forming apparatus 2 and an external device such as the console 5 communicate in the radiographing room R1. Are provided with a wireless access point (base station) 113 for relaying these communications.
The wireless access point 113 is connected to a wireless LAN (Local Area Network) 8 in the facility by a LAN cable or the like, and can communicate with each device provided outside the photographing room R1.

In the radiographing room R1, a signal repeater 116 that relays transmission / reception of signals between the radiation generating apparatus 112 and another apparatus such as the radiation image forming apparatus 2 and the console 5 is provided. The signal repeater 116 is connected to the wireless LAN 8 in the facility by a LAN cable or the like.
The signal repeater 116 functions as a conversion device that converts, for example, a signal output from the radiation generator 112 into a signal for LAN communication suitable for a general HUB or the like. The radiographic image forming apparatus 2 and the console 5 and the radiation generating apparatus 112 can transmit and receive signals via the signal repeater 116. For example, the exposure timing and the reset timing of the radiographic image forming apparatus 2 are linked. The irradiation field, tube position, and the like can be linked in accordance with shooting.

  In the present embodiment, a front room R2 is provided adjacent to the photographing room R1. In the anterior chamber R2, an operation device 115 including an exposure button (not shown) of a radiation generator 112 that radiates radiation onto a subject is provided by a radiologist, a doctor, or the like (hereinafter referred to as an “operator”). Yes. The operation device 115 is connected to the radiation generation device 112 via a cable or the like. When an engineer operates the exposure button in hope of starting imaging, a signal indicating that the exposure button has been pressed is sent to the radiation generation device 112. And is further transmitted from the radiation generator 112 to the console 5 or the like via the signal relay 116.

  Note that a control signal for controlling the radiation irradiation condition of the radiation generator 112 may be transmitted from the console 5 to the operation device 115. In this case, the radiation irradiation condition of the radiation generator 112 is set according to the control signal from the console 5 transmitted to the operation device 115. Examples of radiation irradiation conditions include exposure start / end timing, radiation tube current value, radiation tube voltage value, filter type, and the like.

In the present embodiment, the radiographic image forming apparatus 2 is a cassette type FPD in which a so-called flat panel detector (hereinafter referred to as “FPD”) is configured to be portable, and is used for radiographic imaging to detect radiation. Thus, radiation image data corresponding to the radiation dose (hereinafter simply referred to as “image data”) is generated and acquired.
In the following, a so-called indirect radiation image forming apparatus that includes a scintillator or the like and converts the emitted radiation into electromagnetic waves of other wavelengths such as visible light to obtain an electrical signal will be described as the radiation image forming apparatus 2. However, the present invention can also be applied to a so-called direct type radiation image forming apparatus that directly detects radiation with a radiation detection element without using a scintillator or the like.

FIG. 2 is a perspective view of the radiation image forming apparatus 2 in the present embodiment.
As shown in FIG. 2, the radiation image forming apparatus 2 includes a housing 21 that protects the inside. The housing 21 has at least a surface X on which radiation is received (hereinafter referred to as a radiation incident surface X) formed of a material such as a carbon plate or plastic that transmits radiation. 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 so-called monocoque shape.

  As shown in FIG. 2, in the present embodiment, a power switch 22, an indicator 25, a connection portion 26, and the like are disposed on the side surface portion of the radiation image forming apparatus 2.

  The power switch 22 is used to switch on / off the power of the radiation image forming apparatus 2. By operating the power switch 22, power to each functional unit of the radiation image forming apparatus 2 by the battery 28 (see FIG. 5). A signal instructing the start and stop of the supply is output to the control unit 30 (see FIG. 3) described later. When the radiographic image forming apparatus 2 is not used for imaging, the power consumption of the battery 28 can be suppressed by turning off the power (that is, stopping the power supply to each functional unit by the battery 28).

The indicator 25 is composed of, for example, an LED or the like, and displays the remaining amount of charge of the battery 28 and various operation statuses.
In the present embodiment, for example, it performs a function of notifying the operator of the completion of the reset operation by blinking when the reset is completed.

In addition, the radiation image forming apparatus 2 is provided with a battery 28 (see FIG. 5) that supplies power to each functional unit of the radiation image forming apparatus 2. In the present embodiment, the battery 28 constitutes a power supply unit 27 together with a power supply circuit 29 described later.
The battery 28 is rechargeable, for example, a rechargeable secondary battery such as a nickel cadmium battery, a nickel metal hydride battery, a lithium ion battery, a small sealed lead battery, a lead storage battery, an electric double layer capacitor, a lithium ion capacitor (LIC). ) And the like can be applied.
Among these, a lithium ion capacitor is particularly preferable because it is excellent in power storage efficiency, can be charged at high speed with a large current (for example, 5 to 10 A), and can greatly shorten the charging time.

  Further, a lid member 70 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 radiation image forming apparatus 2. An antenna device 71 is embedded for the image forming apparatus 2 to transmit and receive information to and from the outside via a wireless access point 113 (see FIG. 1) described later.

  The connection unit 26 is a connection unit for connecting a power supply cable (not shown) for charging the battery 28 and an external power supply terminal. The connection unit 26 may be capable of connecting a communication cable (not shown) when performing communication by a wired method in addition to a power feeding cable or the like.

A scintillator layer (not shown) that absorbs radiation incident from the radiation incident surface X and converts it into light having a wavelength including visible 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 by using a phosphor in which a luminescent center substance is activated in a mother body 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. 3) that convert 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 as an arrayed detection unit is provided. The photoelectric conversion element 23 is, for example, a photodiode, and constitutes a radiation detection element that converts the radiation transmitted through the subject into an electrical signal together with the scintillator layer and the like.

  In the present embodiment, a reading unit 45 (see FIG. 3) that is a reading unit that reads the output value of each photoelectric conversion element 23 of the sensor panel unit 24 by the control unit 30, the scanning drive circuit 32, the signal reading circuit 33, and the like. Is configured.

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. 3, one electrode of each photoelectric conversion element 23 of the sensor panel unit 24 is connected to a source electrode of a TFT 46 which is a signal reading switch element. 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 reverse bias voltage is applied from the bias power supply 36 to each photoelectric conversion element 23. It has come to be.

The gate electrode of each TFT 46 is connected to a scanning line Ll extending from the scanning drive circuit 32, and a read voltage (ON voltage) or OFF voltage is applied to the gate electrode of the TFT 46 from a TFT power source (not shown) via the scanning line Ll. Is applied. The drain electrode of each TFT 46 is connected to the signal line Lr. Each signal line Lr is connected to a reading IC 34 in the signal reading circuit 33, and the image signal is subjected to predetermined signal processing in each reading IC 34 and then output to the control unit 30.
Note that one readout IC 34 constituting the signal readout circuit 33 corresponds to a plurality of signal lines Lr, and the number thereof differs depending on the number of signal lines Lr provided in the radiation image forming apparatus 2. The number of signal lines Lr provided in the radiation image forming apparatus 2, the number of signal lines Lr to which one readout IC 34 corresponds, and the like are not particularly limited.

In this embodiment, each reading IC 34 includes a temperature sensor 35 as IC temperature detecting means for detecting the temperature of the reading IC 34. The temperature of the reading IC 34 detected by the temperature sensor 35 is output to the control unit 30.
A storage unit 31 is connected to the control unit 30, and the control unit 30 stores the digital image signal sent from the A / D conversion circuit 40 in the storage unit 31 as image data.

Here, the configuration of the reading IC 34 will be described with reference to FIG.
In this embodiment, each readout IC 34 includes a charge amplifier (amplifier circuit) 37, a sample hold circuit (CDS circuit) 38, an analog multiplexer (MPX) 39, an A / D conversion circuit (ADC) 40, and the like. Yes.
Each signal line Lr connected to the drain electrode of each TFT 46 is connected to a charge amplifier 37 in the readout IC 34, and an output line of each charge amplifier 37 is connected to an analog multiplexer 39 via a sample hold circuit 38. ing. The analog multiplexer 39 is connected to an A / D conversion circuit 40 as processing means for converting a signal into a digital signal. An analog image signal sent from the analog multiplexer 39 is sent by the A / D conversion circuit 40. It is converted into a digital image signal. The image signal converted into a digital signal by the A / D conversion circuit 40 of each readout IC 34 is output to the control unit 30 connected to the signal readout circuit 33.
Note that the configuration of the reading IC 34 is not limited to the one illustrated here. For example, the read IC 34 may not include the A / D conversion circuit (ADC) 40.

The control unit 30 is a computer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like (not shown), and comprehensively controls the entire radiation image forming apparatus 2.
As shown in FIG. 5, in the present embodiment, the control unit 30 switches the power supply ON / OFF by the power supply unit 27 to control the driving state of each functional unit, and the operation of each functional unit. The operation control unit 30b controls the communication and the communication control unit 30c controls the communication.
In FIG. 5, the power supply path from the power supply unit 27 is indicated by a broken line, and the signal flow is indicated by a solid line.

The ROM stores a program for performing various processes in the radiation image forming apparatus 2 such as an image data generation process and a power supply control process, various control programs, parameters, and the like.
The control unit 30 reads a predetermined program stored in the ROM, develops it in a work area of the RAM, and the CPU executes various processes according to the program.

The operation control unit 30b controls the operation of each functional unit when the radiographic image forming apparatus 2 is in a radiographable state. For example, the operation control unit 30b generates image data by the reading unit 45 and performs predetermined signal processing on the image data. The image data is converted into data having a format suitable for outputting the image data to the outside, and the like.
In order to reduce power consumption, the operation control unit 30b is preferably in the sleep state when the radiation image forming apparatus 2 is in the sleep state.

In the present embodiment, the communication control unit 30 c controls the communication unit 41 so as to communicate with the corresponding console 5 through the wireless access point 113.
When the preliminary empty reading operation of the radiation image forming apparatus 2 is completed, the communication control unit 30c transmits a signal to that effect to the corresponding console 5. Further, when the reset process is completed, the communication control unit 30c transmits a reset completion signal to that effect to the corresponding console 5.

  In the present embodiment, a power supply circuit 29 is provided between the battery 28 and each functional unit. The power supply circuit 29 is a circuit for switching ON / OFF whether or not the power from the battery 28 is supplied to each function unit. The power supply control unit 30a controls the power supply circuit 29 so that The drive state of each function unit is controlled by switching ON / OFF the power supply to the function unit.

In the present embodiment, the radiographic image forming apparatus 2 has, as driving states, a radiographable state in which radiographic image capture is possible and a sleep state in which power supply to each functional unit is turned off during non-imaging, When shooting is not performed for several minutes, the power supply to each function unit is automatically turned off to enter a sleep state.
That is, during non-photographing, in order to prevent wasteful power consumption of the battery 28, the power supply control unit 30a is powered off so as to turn off the power supply except for some functional units such as the communication unit 41 that receives communication from the console 5. The circuit 29 is controlled. In response to a command from the power supply control unit 30a, the power supply circuit 29 turns off (stops) the power supply to the reading unit 45 and the like.

When the radiographic image forming apparatus 2 receives a signal to start imaging from the console 5, the radiographic image forming apparatus 2 transitions from the sleep state to the imaging enabled state.
When shifting from the sleep state to the photographing enabled state, the power supply control unit 30a controls the power supply circuit 29 to turn on the power supply from the battery 28 to the reading IC 34, and performs a preliminary empty reading operation before starting the photographing. Let it be done.

  As the empty read operation, for example, an off voltage is applied to the gate of the TFT 46 and only the read operation by the read IC 34 is performed while the gate is closed. By driving the readout IC 34 in advance, the temperature of the readout IC 34 rises, and subsequent imaging can be performed at a stable temperature.

  In this empty read operation, it is not necessary to operate all the components of the read IC 34. For example, only the charge amplifier (amplifier circuit) 37 and the sample hold circuit (CDS circuit) 38 may be operated. However, when the A / D converter circuit (ADC) 40 is operated, the temperature of the read IC 34 can be expected to rise more. Therefore, the entire read IC 34 including the A / D converter circuit (ADC) 40 is operated. It is preferable to make it.

  Note that reading may be performed with an on-voltage applied to the gate of the TFT 46 to open the gate. In this case, the charge accumulated in the gate can be released by this preliminary empty read operation, and it can also serve as a reset operation. As described above, when the preliminary empty read operation is also used as the reset operation, the gates may be sequentially opened for each signal line Lr, or the read operation may be performed for all the signal lines Lr at once. May be performed.

  Although the time for performing the empty reading operation is not particularly limited, it is necessary to raise the temperature of the reading IC 34 to such an extent that the subsequent shooting can be stably performed. The empty reading operation is performed until the temperature reaches a certain temperature.

Specifically, for example, the power supply control unit 30a monitors the temperature of the read IC 34 detected by the temperature sensor 35 built in the read IC 34, and continues the empty read operation until the temperature reaches a predetermined target temperature or higher.
Here, the predetermined target temperature is, for example, a temperature in the vicinity of the temperature of the reading IC 34 detected before entering the sleep state, for example, reading of the reset start time at the time of the last dark image photographing before entering the sleep state. When the temperature of the IC 34 (referred to as “origin temperature t0”) is used as a reference, the temperature is about two degrees lower than this. Since the temperature detected at the start of resetting at the time of the last dark image shooting before entering the sleep state can be said to be a relatively stable temperature in the radiation image forming apparatus 2, this temperature is set before entering the actual shooting operation. This is because image data with little influence of temperature drift can be obtained by raising the temperature of the reading IC 34 until the temperature becomes about 2 degrees lower than the origin temperature t0.
Note that the temperature at the start of resetting when dark image shooting is performed after acquiring the actual image data and transferring the image data is the temperature at the start of resetting at the time of the last dark image shooting before entering the sleep state. Since the temperature is close and relatively stable, this temperature is illustrated in FIG. 6 as being substantially equal to the origin temperature t0.

Note that the degree of the predetermined target temperature may be arbitrarily set according to the usage environment of the radiation image forming apparatus 2 or the like.
Further, the temperature used as a reference for determining whether or not the target temperature is the predetermined target temperature is not limited to the temperature of the reading IC 34 at the time of reset start when acquiring the last dark image data before entering the sleep state. The temperature when the offset correction value and the gain correction value are acquired at the time of shipment of the apparatus 2 may be stored in the storage unit 31 or the like, and this temperature may be used as a reference (that is, the origin temperature t0). Further, a temperature sensor (that is, a temperature sensor as an internal temperature detecting means, not shown) that detects the temperature inside the casing 21 is provided as the temperature inside the radiation image forming apparatus 2 and is detected by this temperature sensor. The temperature inside the casing 21 may be used as a reference (that is, the origin temperature t0).

  The storage unit 31 is configured by, for example, an HDD (Hard Disk Drive), a flash memory, or the like. The storage unit 31 includes actual image data generated by the reading unit 45 (see FIG. 3) (radiation transmitted through the subject). Based image data), a dark read value (image data of a dark image acquired without radiation), a predetermined target temperature serving as a reference for causing the read IC 34 to perform an empty read operation, and the like are stored. Yes.

  The storage unit 31 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.

The communication unit 41 is connected to the antenna device 71 and transmits and receives various signals to and from an external device such as the console 5 under the control of the control unit 30. The communication unit 41 communicates with an external device such as the console 5 in a wireless manner via the wireless access point 113.
In the present embodiment, when the preliminary empty read operation is completed, the communication unit 41 sends a signal to that effect to the console 5.
When the control unit of the console 5 receives a signal indicating that the preliminary empty reading operation has been completed, the control unit sends an instruction signal to enter the operation for photographing. Upon reception, the control unit 30 of the radiation image forming apparatus 2 controls the reading unit 45 and the like so as to perform a reset operation.
The communication unit 41 transmits image data based on the image signal read by the reading unit 45 and converted from an analog signal to a digital signal in the A / D conversion circuit 40 to the console 5 that is an external device and from the console 5 or the like. Shooting order information and the like can be received.

  The console 5 is a computer configured to include a control unit including a CPU (Central Processing Unit), a storage unit, an input unit, a display unit, a communication unit, and the like (all not shown).

  The storage unit of the console 5 stores various programs such as a program for performing image processing such as gradation processing and frequency processing based on automatic part recognition for detecting an affected part, and also for captured images. Stored are image processing parameters for adjusting image data to an image quality suitable for diagnosis (lookup table defining a gradation curve used for gradation processing, enhancement degree of frequency processing, and the like).

  When the image data is sent from the radiation image forming apparatus 2, the console 5 appropriately performs offset correction or gain correction to generate diagnostic image data.

  The communication unit is connected to the wireless LAN 8 and transmits / receives information to / from the radiation image forming apparatus 2 and the like via the wireless access point 113 provided in the imaging room R corresponding to each console 5.

  When the preliminary empty reading operation is completed from the radiation image forming apparatus 2, a signal to that effect is sent to the control unit of the console 5. The controller of the console 5 performs the preliminary empty reading operation. When a signal indicating the completion is sent, an instruction signal is issued to the radiation image forming apparatus 2 and the radiation generating apparatus 112 so as to start an operation for imaging.

Further, the control unit of the console 5 determines whether or not the reset processing of the radiation image forming apparatus 2 has been completed and is in a state suitable for imaging.
Specifically, it is determined whether or not a reset completion signal indicating that the reset process has been completed is received from the radiation image forming apparatus 2.

In the present embodiment, the control unit of the console 5 controls the communication unit to output an exposure prohibition signal (interlock signal) so as to maintain the exposure prohibition state with respect to the radiation generator 112. Yes. The exposure prohibition signal (interlock signal) is output to the radiation generator 112 via, for example, a LAN cable and a signal repeater 116 (not shown).
Even if a signal indicating that the exposure button has been operated is transmitted from the radiation generator 112, the control unit, as long as the reset completion signal is not received from the radiation image forming apparatus 2, ) Is output and the exposure prohibited state is maintained.

  The input unit includes, for example, 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 as input signals.

  The display unit includes, for example, a monitor such as a CRT (Cathode Ray Tube) or an LCD (Liquid Crystal Display). The display unit may have a higher definition than a monitor used in a general PC (Personal Computer).

  In addition to the data management server, the console 5 may be connected to an external device such as a HIS / RIS, an imager, or the like (all not shown) via a network. Note that the external device connected to the console 5 via the network is not limited to the one exemplified here.

Next, the operation of the radiation image forming apparatus 2 in the present embodiment will be described with reference to FIG.
When the radiographic image forming apparatus 2 receives a signal to start imaging from the console 5 (referred to as “activation signal” in FIG. 6), the radiographic image forming apparatus 2 transitions from the sleep state to the imaging enabled state.
Then, when shifting from the sleep state to the photographing enabled state, the power supply control unit 30a controls the power supply circuit 29 to turn on the power supply from the battery 28 to the reading IC 34, and prior to the empty reading, before the photographing starts. Let the action take place.

As shown in FIG. 6, the temperature of the readout IC 34 in the sleep state is considerably lower than the temperature when the radiation image forming apparatus 2 is used for imaging, but a preliminary empty readout operation is performed. As a result, the temperature of the reading IC 34 rises, and after the standby state after the preliminary empty reading operation, the image data transfer is completed and a stable temperature similar to that at the start of the reset for the dark image (in FIG. 6). The temperature rises to near the origin temperature (t0). The power supply control unit 30a constantly monitors the temperature of the readout IC 34 detected by the temperature sensor 35, and the temperature of the readout IC 34 starts to be reset at a predetermined target temperature (for example, the last dark image shooting before entering the sleep state). The read operation is continued until the temperature of the read IC 34 at the time (that is, a temperature that is about 2 degrees lower than the origin temperature t0).
When the temperature of the reading IC 34 rises to a predetermined target temperature, the power supply control unit 30a ends the previous empty reading operation. Then, the radiation image forming apparatus 2 transmits a signal indicating that the empty reading operation is completed to the console 5 and enters a standby state until an instruction signal is transmitted from the console 5 to enter the operation for imaging.

In the present embodiment, a temperature that is about two degrees lower than the origin temperature t0 is set as the predetermined target temperature. When the temperature of the reading IC 34 becomes equal to or higher than the predetermined target temperature, the preliminary empty reading operation is terminated and the standby state is set. However, since the power supply to the reading IC 34 continues even in this standby state, the temperature of the reading IC 34 gradually increases. Then, the temperature difference (“t1” in FIG. 6) between the temperature (“t1” in FIG. 6) and the origin temperature t0 at the time of starting reset for shooting the real image is such that it does not affect the shooting. Very little.
In contrast to this, as in the prior art, when no prior empty read operation is performed at the time of startup, the temperature of the read IC 34 changes from the standby state as indicated by the broken line in FIG. The temperature starts to increase little by little, but the temperature (“t2” in FIG. 6) at the start of resetting for taking a photographed image remains considerably lower than the origin temperature t0. Therefore, the temperature difference between the temperature t2 and the origin temperature t0 (“Δt2” in FIG. 6) becomes so large that there is a possibility of causing image noise due to temperature drift.

Next, for example, when a radiologist or the like operates the exposure button of the operation device 115 in the front room R2, a signal indicating that the exposure button has been operated is sent from the radiation generation device 112 via the signal relay 116 to the console 5. The console 5 transmits an instruction signal to the radiation image forming apparatus 2 or the like so as to enter an operation for imaging.
When the instruction signal is transmitted from the console 5, the control unit 30 controls the sensor panel unit 24, the detection unit 45, and the like to perform a reset operation. When the reset operation is completed, a reset completion signal is transmitted to the console 5.

  The communication unit of the console 5 outputs an exposure prohibition signal (interlock signal) for prohibiting exposure to the radiation generator 112 in the corresponding imaging room R1 via a LAN cable or the like. As long as this exposure prohibition signal is not canceled, even if the exposure button of the operation device 115 is operated, the state in which the exposure of the radiation generator 112 is prohibited is maintained. And the control part of the console 5 judges whether the reset completion signal was received from the radiographic image forming apparatus 2 used for imaging | photography, and when not receiving a reset completion signal, the output of an exposure prohibition signal is output. The state where the radiation generator 112 is prohibited from being exposed is not released. On the other hand, when the reset completion signal is received, the output of the exposure prohibition signal to the radiation generator 112 is canceled. Thereby, radiation is exposed from the radiation generator 112 and imaging is performed.

When exposure is performed, charges are accumulated, and reading by the signal reading circuit 33 is started after a predetermined time has elapsed. When the reading by the signal reading circuit 33 is completed, the shooting of the photographed image is completed, and the image data (real photographed image data) acquired by the shooting is transferred to the console 5.
Thereafter, after the reset operation is performed, electric charges are accumulated for the same period of time as actual captured image shooting without radiation irradiation, and reading by the signal readout circuit 33 is performed after a predetermined time has elapsed (that is, dark image capturing). Note that while the image data is being transferred, the temperature of the reading IC 34 gradually decreases, but dark image shooting can be performed at a stable temperature comparable to that in the standby state for actual image shooting. The dark image data can be acquired under the same conditions as the real image data. When the reading by the signal reading circuit 33 is completed, the dark image shooting is finished, and the image data (dark image data) acquired by the shooting is transferred to the console 5.

  The method of transferring the image data is not particularly limited. For example, after the shooting of the photographed image, first, one-fourth thinned-out data of the photographed image data is transmitted to the console 5, and then the dark image shooting is performed. After the data is acquired, the thinned data of ¼ of the dark image data may be transmitted to the console 5, and the remaining three quarters of the real image data and the dark image data may be sequentially transmitted. Further, with respect to the dark image data, the thinned data may not be sent, and all the data of the dark image may be sent after all the actual image data is sent.

  Further, it is not always necessary to start all the components of the reading IC 34 when taking an image. For example, when reading is performed, only the charge amplifier (amplifying circuit) 37 and the sample hold circuit (CDS circuit) 38 are used. And the power supply of the A / D conversion circuit (ADC) 40 may be turned off. Then, after performing an offset process for subtracting dark image data from actual image data, the power of the charge amplifier (amplifier circuit) 37 and the sample hold circuit (CDS circuit) 38 is turned off, and the A / D converter circuit (ADC). 40 may be activated, A / D conversion may be performed on the data after image processing, and the data may be transmitted to the console 5. Thus, the power consumption can be further reduced by finely switching ON / OFF of the power supply for each component of the read IC 34.

  If the imaging operation is not performed for a certain period, the radiographic image forming apparatus 2 again enters the sleep state in which the power supply to each functional unit is turned off.

As described above, according to the present embodiment, when a transition from the sleep state to the photographing enabled state is performed, a preliminary empty reading operation is performed to increase the temperature of the reading IC 34 to a predetermined target temperature. Even in such a state, the temperature drift of the readout IC 34 can be suppressed, and the generation of image noise due to the temperature drift can be reduced. That is, reading by the reading IC 34 is easily affected by temperature, but the reading operation can be performed at a stable temperature by raising the temperature of the reading IC 34 in advance.
Further, in the empty read operation, when the power supply 27 is switched on / off so that power is also supplied to the A / D conversion circuit 40, the temperature of the read IC 34 is increased more effectively. Can be made.
Further, since the temperature of the read IC 34 can be detected by the temperature sensor 35 incorporated in the read IC 34 and it can be monitored whether the predetermined target temperature has been reached, the temperature of the read IC 34 can be surely raised to the predetermined target temperature. Can do.

In this embodiment, the temperature of the reading IC 34 is detected by the temperature sensor 35 and the empty reading operation is continued until the temperature reaches a predetermined target temperature. However, a method for stabilizing the temperature of the reading IC 34 is described. It is not limited to this.
For example, when the temperature of the reading IC 34 is lowered to about room temperature in the sleep state for a long time, it is measured in advance how long it takes until the temperature drift of the reading IC 34 becomes stable and shows a constant temperature. Then, it may be stored in the storage unit 31 or the like, and this empty time readout operation may be performed.
Alternatively, the empty read operation may be performed while monitoring the change in the output value of the read IC 34, and the empty read operation may be performed until the output value of the read IC 34 becomes constant.
In the case of these methods, it is not necessary to provide the temperature sensor 35 in the reading IC.

  In the present embodiment, all the read ICs 34 are driven in the preliminary empty read operation. However, when the temperature can be sufficiently raised by driving some of the read ICs 34, some of the read ICs 34 are partially driven. Only the read IC 34 may be driven. In this case, for example, the read IC 34 to be driven may be sequentially changed every time the empty read operation is performed.

  In addition, it cannot be overemphasized that this invention is not limited to this embodiment, and can be changed suitably.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. Note that the second embodiment differs from the first embodiment in the method for stabilizing the temperature of the read IC. Therefore, the following description will focus on differences from the first embodiment.

In this embodiment, the power supply control unit of the radiographic image forming apparatus turns on the power supply of the power supply unit that periodically supplies power to the reading IC even when the radiographic image forming apparatus is in the sleep state, and performs empty reading to the reading IC. The action is to be performed.
That is, for example, in the sleep state, power is supplied to the read IC every minute or the like, and a preliminary empty read operation is performed.
As a result, the temperature of the reading IC does not drop too much even in the sleep state, and can be maintained at a constant and stable temperature, which is suitable for acquiring image data immediately when the state shifts to the photographing enabled state. It becomes a state.

  The timing for performing the empty read operation is not particularly limited. For example, even when the radiographic image detection device is in the sleep state, if there is a query about the driving state etc. from the console periodically, the empty read-out operation in advance is performed when there is an inquiry from this console. You may make it perform.

Further, the empty read operation does not necessarily have to be performed periodically. For example, the empty read operation is performed only when the temperature of the read IC is periodically detected and it is determined that the temperature is equal to or lower than a predetermined target temperature. May be performed.
The predetermined target temperature or lower is, for example, the temperature of the read IC 34 at the start of resetting at the time of obtaining the last dark image data before entering the sleep state (in FIG. 7), as described in the first embodiment. The origin temperature t0) is used as a reference, and the temperature is lower than a predetermined temperature by more than a predetermined temperature. In this case, the empty read operation is performed. How much the target temperature is set, that is, how much lower than the reference temperature (that is, the origin temperature t0), the empty read operation may be arbitrarily set. When the temperature is lower than the reference temperature (that is, the origin temperature t0) by 2 degrees or more, the empty read operation is performed.
In this case, the target temperature, which is a criterion for determining whether or not to perform the empty reading operation, is based on the temperature of the reading IC at the time of starting reset at the time of obtaining the last dark image data before entering the sleep state. It is not limited to things. For example, the target temperature may be set based on the temperature inside the housing.
Alternatively, the temperature at which the offset correction value and gain correction value are acquired at the time of shipment of the readout IC or the like may be stored in a recording unit or the like, and the target temperature may be set based on this.

Although the time for performing the empty read operation is not particularly limited, for example, a temperature sensor for detecting the temperature of the read IC is provided in the same manner as described in the first embodiment, and the temperature detected thereby is a predetermined temperature. The empty read operation may be performed until the above is reached. The predetermined temperature mentioned here can also be set by the same method as the target temperature.
Further, the output value of the read IC may be monitored, and the empty read operation may be performed until it becomes constant.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

Next, the operation of the radiation image forming apparatus according to the present embodiment will be described with reference to FIG.
While the radiation image forming apparatus is in the sleep state, the power supply control unit periodically turns on the power supply to the reading IC and performs the empty reading operation. Whether the empty read operation is performed or how long it is performed is determined based on whether the temperature of the read IC is obtained from the temperature sensor and whether the temperature is below a predetermined target temperature or the like. As a result, as shown in FIG. 7, the temperature of the read IC is not greatly lowered even during the sleep state, and the read IC is kept in a stable state.
When a signal to start imaging from the console (referred to as “activation signal” in FIG. 7) is received, the driving state of the radiation image forming apparatus changes from the sleep state to the imaging enabled state.

  Note that the following processing is the same as that of the first embodiment, and a description thereof will be omitted.

In the present embodiment, since the empty read operation is periodically performed even during the sleep state, the temperature of the read IC 34 is kept constant. Since the power supply to the reading IC 34 continues even after shifting to the standby state after startup, the temperature of the reading IC 34 gradually increases, and the temperature at the time when resetting for actual image shooting is started (see FIG. The temperature difference between “t1” in FIG. 7) and the origin temperature t0 (“Δt1” in FIG. 7) is very small so as not to hinder photographing.
In contrast to this, when no empty read operation is performed in the sleep state as in the prior art, the temperature of the read IC 34 gradually increases after entering the standby state, as indicated by a broken line in FIG. Although the temperature starts to rise, the temperature (“t2” in FIG. 7) at the time when resetting for capturing a photographed image is started remains substantially lower than the origin temperature t0. For this reason, the temperature difference between the temperature t2 and the origin temperature t0 (“Δt2” in FIG. 7) becomes so large that there is a possibility of causing image noise due to temperature drift.

  As described above, according to the present embodiment, even when the radiation image forming apparatus is in the sleep state, the power supply to the reading IC is periodically turned ON to perform the empty reading operation. As a result, the temperature of the readout IC does not drop too much and is kept at a constant and stable temperature, so that it is possible to immediately make a state suitable for photographing when the state shifts to the photographing ready state. For this reason, the temperature drift of the readout IC 34 can be suppressed, and the generation of image noise due to the temperature drift can be reduced. That is, reading by the reading IC is easily affected by temperature, but the reading operation can be performed at a stable temperature by raising the temperature of the reading IC in advance.

  In this embodiment, the empty read operation is performed only during the sleep state. However, the empty read operation is also performed when the shooting state is shifted from the sleep state as in the first embodiment. You may make it raise the temperature of IC.

  In each of the above embodiments, the case where the radiographic image forming apparatus 2 and the console transmit and receive information using a wireless LAN has been described as an example. However, the communication method between the radiographic image forming apparatus and the console is a wireless LAN. It is not limited.

  In each embodiment, offset correction value information, gain correction value information, and the like for each radiographic image forming apparatus may be held and managed by the data management server, or stored in the storage unit of the console for each radiographic image forming apparatus. Offset correction value information, gain correction value information, and the like may be stored.

  Moreover, although each embodiment demonstrated as an example the case where the operating device provided in the front chamber R2 was provided with the exposure button of the radiation generator, the exposure button of the radiation generator was provided in the operating device. It is not limited to the case. For example, an exposure button may be provided on the console.

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

2 Radiation image forming apparatus 5 Console 7 Data management server 24 Sensor panel unit 25 Indicator 26 Connection unit 30 Control unit 34 Reading IC
35 Temperature Sensor 37 Charge Amplifier 40 A / D Conversion Circuit R1 Shooting Room

Claims (8)

A radiographic image forming apparatus having a radiographable state capable of radiographic imaging and a sleep state in which power supply to each functional unit is turned off during non-imaging as a driving state,
A plurality of radiation detection elements constituting the pixel are arranged in a two-dimensional matrix to detect radiation; and
A readout IC that includes a charge amplifier and the like, and reads out an output value of each radiation detection element of the sensor panel unit in units of pixels;
A power supply unit for supplying power to each functional unit including the readout IC;
A control unit that controls ON / OFF of power supply by the power supply unit to control a driving state of each functional unit;
The control unit turns on the power supply by the power supply unit that supplies power to the read IC when the sleep state or the transition from the sleep state to the photographing enabled state, and performs a read operation on the read IC A radiation image forming apparatus. The read IC has an A / D conversion circuit,
The control unit switches ON / OFF of power supply by the power supply unit so that power is also supplied to the A / D conversion circuit when shifting from the sleep state to a photographing enabled state. Item 2. The radiographic image forming apparatus according to Item 1. IC temperature detecting means for detecting the temperature of the readout IC,
When shifting from the sleep state to the photographing enabled state, the control unit causes the read IC to perform a read operation until the temperature of the read IC detected by the IC temperature detection unit becomes constant. The radiation image forming apparatus according to claim 1.   The control unit causes the read IC to perform a read operation until the output value of the read IC becomes constant when shifting from the sleep state to the photographing enabled state. The radiographic image forming apparatus as described in any one of Claims.   2. The control unit according to claim 1, wherein in the sleep state, the control unit periodically turns on power supply from the power supply unit that supplies power to the read IC, and causes the read IC to perform a read operation. The radiographic imaging apparatus described. IC temperature detecting means for detecting the temperature of the readout IC,
The control unit causes the read IC to perform a read operation so that a temperature of the read IC detected by the IC temperature detection unit is equal to or higher than a predetermined target temperature in the sleep state. 5. The radiographic image forming apparatus according to 5. Internal temperature detection means for detecting the temperature inside the device;
IC temperature detecting means for detecting the temperature of the readout IC,
The control unit sets the target temperature of the readout IC in the sleep state with reference to the temperature inside the device detected by the internal temperature detection unit,
6. The radiographic image formation according to claim 5, wherein the readout IC is caused to perform a readout operation so that a temperature of the readout IC detected by the IC temperature detection means is equal to or higher than the set target temperature. apparatus.   8. The radiation image forming apparatus according to claim 3, wherein the IC temperature detection unit is built in the readout IC.

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