JP2010214056A - Radiographic image detector and radiological image generating system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiological image generating system which can properly detect an amount of irradiation when a irradiation-amount calculation part provided for itself detects the amount of irradiation. <P>SOLUTION: In the radiological image generating system, a radiographic image detector 6 transmits the amount of irradiation for a photographing block, which corresponds to selection instructions transmitted from a controller 7, to the controller 7. The controller 7 indicates the received amount of irradiation on its display 77. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a radiological image detection apparatus that detects radiation transmitted through a subject, and a radiological image generation system using the same.

  Image data obtained by irradiating a subject with radiation and passing through the subject is widely used as a medical image for diagnosis. In radiography, it is important to appropriately control the radiation dose. When the irradiation amount is excessive, an excessive exposure dose of the subject becomes a problem. When the irradiation amount is inappropriate, appropriate image data cannot be obtained due to overexposure or underexposure.

  A means for obtaining an appropriate image by irradiating a subject with an appropriate dose of radiation includes an AEC sensor (AEC: Automatic Exposure Control). The AEC is provided on an extension line connecting the radiation irradiation apparatus and the subject. In the AEC control, the radiation irradiation time is controlled in accordance with the irradiation amount detected by the AEC sensor.

  In recent years, FPD (Flat Panel Detector) has been used. An FPD is a two-dimensional array of a plurality of detection elements on a substrate. Radiation that has passed through a subject is irradiated onto a phosphor (scintillator), and visible light emitted according to the amount of irradiation is detected. A radiation image is obtained by converting the charge into a capacitor and storing it in a capacitor by reading the charge stored in the capacitor. Compared to the above-described system using a CR cassette, there is an advantage in that image data can be obtained directly without using a reading device. In addition, the semiconductor manufacturing technology has been improved to reduce the size and thickness, and by using a cassette-type FPD that is the same size as the CR cassette, a photo frame (so-called “buoy device”) on which the CR cassette used in the CR system is mounted. Therefore, there is an advantage that the introduction cost can be suppressed.

  Also in the FPD, the irradiation amount at the time of photographing can be optimized by using the AEC sensor. In order to optimize the irradiation amount with the AEC sensor, it is necessary to provide it on the extended line connecting the radiation irradiation device and the subject as described above. However, the subject is not positioned properly and the subject is transmitted through the radiation irradiation device. If the radiation reaches the AEC sensor directly without being detected, even if the output is appropriate, it is erroneously detected as an excessive output. As a result, there is a problem that the amount of radiation is insufficient and proper image data cannot be obtained.

  In the X-ray imaging control apparatus described in Patent Document 1, a plurality of AEC sensors are provided, and an AEC sensor to be used can be selected from these during imaging, and the AEC sensor selected for image data obtained by imaging By superimposing the positions and displaying them on the display, it is clearly shown to the photographer whether the positional relationship between the AEC sensor position used at the time of photographing and the subject is appropriate.

  Further, in the radiation imaging apparatus described in Patent Document 2 (particularly, paragraph 0084), the signal read out by the nondestructive readout method output from the imaging panel is compared with the reference value, so that the radiation imaging apparatus itself is optimal as the AEC sensor. The amount of exposure is evaluated.

Japanese Patent Laid-Open No. 2005-212514 JP 2003-126072 A

  Since the FPD can store a plurality of pieces of image data in its internal storage memory, it can continuously shoot. FPD is more expensive than CR cassette. In a CR cassette that is relatively inexpensive, it is easy to prepare a plurality of cassettes corresponding to various photographing sizes, but it is difficult because an FPD is expensive. In view of this, there are many situations in which FPD cassettes are prepared with large cassettes, and photography that has conventionally been performed with small cassettes is also performed with the large FPD cassettes.

  In such a situation, the size of the FPD cassette becomes larger than necessary compared to the imaging region of the subject. As a result, since the region where the FPD detection element is directly irradiated with radiation without passing through the subject increases, it is affected by the direct irradiation unit, and an appropriate irradiation amount is assumed as a whole due to excessive irradiation. May not be obtained.

  In view of the above problems, the present invention has an object to provide a radiation image generation system capable of appropriately detecting a dose when the dose calculation unit included in the present invention detects the dose of radiation. To do.

  The above object is achieved by the invention described below.

1. A radiation irradiation device;
An imaging panel in which a plurality of detection elements that convert energy corresponding to an irradiation amount irradiated from the radiation irradiation apparatus and transmitted through the subject into a charge amount are arranged in a matrix;
An image data generation unit that generates image data from the amount of charge obtained by the detection element;
A plurality of bias lines for supplying a reverse bias voltage to the detection elements in each imaging block as a plurality of imaging blocks as detection elements of the imaging panel;
A power supply for applying a reverse bias voltage to the detection element via the bias line;
A current detection unit for detecting a current flowing through each of the bias lines;
An input unit for inputting an instruction to select at least one shooting block from the plurality of shooting blocks by the photographer;
A radiation image generation system comprising: an irradiation amount calculation unit that calculates an irradiation amount irradiated on at least a selected imaging block based on a detection value by the current detection unit.

2. A control device including the input unit and a display unit;
2. The radiation image generating system according to item 1, wherein an irradiation amount of the selected imaging block is displayed on the display unit.

  3. The radiological image generation system according to 2, wherein the control device displays the generated image data on the display unit together with position information of the imaging block.

  4). The control device calculates a difference irradiation time with respect to an appropriate irradiation time based on the optimum radiation dose j1 of the imaging panel and the dose j2 of the selected imaging block, and the difference irradiation time is displayed on the display unit. The radiation image generation system according to 2 or 3, wherein the radiation image generation system is displayed.

  5. Any one of 1 to 4 above, wherein the detection of the radiation by the imaging panel is detected by detection of the current detection unit, and the detection element is shifted to a charge accumulation state based on the detection. The radiation image generating system described in 1.

6). An imaging panel in which a plurality of detection elements that convert energy corresponding to the amount of irradiation irradiated from the radiation irradiation apparatus and transmitted through the subject into a charge amount are arranged in a matrix;
An image data generation unit that generates image data from the amount of charge obtained by the detection element;
A plurality of bias lines for supplying a reverse bias voltage to the detection elements in each imaging block as a plurality of imaging blocks as detection elements of the imaging panel;
A power supply for applying a reverse bias voltage to the detection element via the bias line;
A current detection unit for detecting a current flowing through each of the bias lines;
An irradiation amount for calculating an irradiation amount irradiated on the basis of a detection value by the current detection unit for at least a selected shooting block in response to a selection instruction for selecting at least one shooting block from the plurality of shooting blocks by a photographer A radiation image detection apparatus comprising a calculation unit.

  7). 7. The radiological image detection apparatus according to 6, wherein the detection of the radiation is started by detection of the current detection unit, and the detection element is changed to a charge accumulation state based on the detection.

  According to the present invention, the imaging panel is divided into a plurality of shooting blocks, and the irradiation amount can be detected for each shooting block, and by calculating the irradiation amount for the selected shooting block, The radiation dose can be optimized.

It is a figure which shows schematic structure of the radiographic image generation system in this embodiment. 3 is a block diagram showing a main part configuration of a console 7. FIG. It is a block diagram which shows the principal part structure of FPD6. It is a perspective view of FPD6. 4 is a cross-sectional view of an imaging panel 62. FIG. 4 is a schematic diagram illustrating a circuit configuration of an imaging panel 62 and a current detection unit 634. FIG. It is a figure which shows an example of the time change of the voltage value converted and output from an electric current by the electric current detection part 634. FIG. It is an example of FPD6 comprised by two imaging | photography blocks. It is explanatory drawing of the control flow which the radiographic image generation system which concerns on 1st Embodiment performs. The display example of the display screen 772 displayed on the display part 77 is shown. It is explanatory drawing of the control flow which the radiographic image generation system which concerns on 2nd Embodiment performs. It is explanatory drawing of the control flow which the radiographic image generation system which concerns on 3rd Embodiment performs.

  Although the present invention will be described based on an embodiment, the present invention is not limited to the embodiment.

  The configuration of the radiation image generation system according to the present embodiment will be described with reference to FIGS. FIG. 1 is a diagram showing a schematic configuration of a radiation image generation system in the present embodiment.

  As shown in FIG. 1, the radiation image generation system includes an imaging operation device 4 that performs operations related to radiation imaging, an access point 5 that performs wireless communication by a wireless LAN (Local Area Network), and a radiation image detection device 6. A console 7 that performs image processing on image data generated by (hereinafter simply referred to as FPD 6) is connected through a network N. Although not shown here, the radiological image generation system includes a network information processing system (HIS) that manages patient diagnosis information and accounting information in a unified manner, and an RIS (Radiology Information System) that manages radiological information and a network N. Connected through. The network N may be a communication line dedicated to the system, but is preferably an existing line such as Ethernet (registered trademark) because the degree of freedom of the system configuration is low.

  Reference numeral 100 denotes a photographing room. The imaging room 100 includes a radiation irradiation device 3, an imaging operation device 4, an access point 5 that performs wireless communication, and a HUB 9 that connects these.

  The radiation irradiation device 3 is configured to irradiate a patient 12 as a subject lying on the supine photographing stand 11, and a detection device equipped with an FPD 6 is mounted below the supine photographing stand 11. A mouth 11a is provided. The radiation irradiation device 3 is controlled by the imaging operation device 4 to perform radiation imaging under predetermined imaging conditions. Note that the synchronization of the imaging timing between the radiation irradiation device 3 and the FPD 6 attached to the detection device attachment port 11a may be performed by wireless communication via the access point 5 between them.

  The access point 5 has a function of relaying these communications when the FPD 6 and the console 7 communicate wirelessly within a predetermined area of the imaging room provided with the radiation irradiation device 3. Note that an example in which wireless communication is performed by a wireless LAN (for example, a communication method compliant with IEEE802.11a / b / g) will be described, but the present invention is not limited to this. Wireless communication may be performed by optical wireless communication (for example, IrDA) using light beams or the like (laser or the like), or acoustic communication using sound waves or ultrasonic waves.

  In the description of FIG. 1, an example in which communication is performed by wireless communication via the wireless access point 5 has been described. However, the present invention is not limited to this, and a communication connector that connects to the network N is provided in the detection device mounting port 11a. May be connected to the network N by being mounted in the detection device mounting port 11a.

[Console 7]
FIG. 2 is a block diagram showing a main configuration of the console 7 functioning as a “control device”. As shown in FIG. 2, the console 7 includes a control unit 74, a RAM (Random Access Memory) 75, a ROM (Read Only Memory) 76, a display unit 77, an input operation unit 78, a communication unit 79, a storage unit 70, and the like. Each part is connected by a bus 71.

  The control unit 74 is configured by a CPU (Central Processing Unit) or the like, and is configured to read a predetermined program stored in the ROM 76, develop it in a work area of the RAM 75, and execute various processes according to the program.

  The display unit 77 includes, for example, a CRT (Cathode Ray Tube), an LCD (Liquid Crystal Display), and the like, and according to instructions of a display signal sent from the control unit 74, the patient list, various messages and images, Various screens are displayed.

  The input operation unit 78 functions as an “input unit” and can input various instructions. For example, it is composed of a keyboard, a mouse, and the like, and outputs a key pressing signal pressed by the keyboard and an operation signal from the mouse to the control unit 74 as input signals. The input operation unit 78 outputs position information input by touching a transparent sheet panel covering the display screen of the display unit 77 with a finger or a dedicated stylus pen as an input signal to the control unit 74, so-called You may be comprised with the touch panel. Further, the radiographer can input imaging order information from the input operation unit 78.

  As an example of the imaging order information, there is information including an imaging order ID, a patient ID, a name, a gender, an age, a medical department as imaging information, an imaging part, and an imaging direction.

  The storage unit 70 stores characteristic information of the FPD 6. Here, the characteristic information is a characteristic of an FPD detection element (also referred to as a light receiving element or a photoelectric conversion element) to be described later, a characteristic of a scintillator panel, or a value of an optimum dose j1 depending on sensitivity. The optimal dose j1 may be a plurality of different values according to the information on the imaging region (affected part). Further, when the characteristic information of each FPD 6 is different in a system using a plurality of FPDs 6, each FPD 6 is managed by an identification ID, and the characteristic information is stored in the storage unit 70 in correspondence with the identification ID. Image processing may be performed on the image data based on the characteristic information.

  The communication unit 79 communicates with each device connected to the network N. Various types of information are communicated with the FPD 6 by the wireless communication method such as wireless LAN through the access point 5 connected to the network N by the communication unit 79.

[FPD6]
The FPD 6 that functions as a radiation image detection device will be described with reference to FIGS. FIG. 3 is a block diagram showing a main configuration of the FPD 6, and FIG. 4 is a perspective view of the FPD 6. FIG. 5 is a cross-sectional view of the imaging panel 62. FIG. 6 is a schematic diagram illustrating circuit configurations of the imaging panel 62 and the current detection unit 634.

  As shown in FIG. 3, the control system of the FPD 6 includes a control unit 64, a RAM 65, a ROM 66, an imaging panel 62, a storage unit 60, a power supply unit 67, a wireless communication unit 69, a current detection unit 634, and the like. Connected by.

  The control unit 64 is composed of, for example, a CPU or the like, reads a control program stored in the ROM 66, develops it in a work area formed in the RAM 65, and controls each unit of the FPD 6 according to the control program. The ROM 66 is constituted by a nonvolatile semiconductor memory or the like, and stores a control program executed by the control unit 64, various programs, a cassette ID of the FPD 6, and the like. The RAM 65 forms a work area for temporarily storing various programs that can be executed by the control unit 64 read from the ROM 66, input or output data, parameters, and the like in various processes controlled by the control unit 64. .

  The storage unit 60 includes, for example, a non-volatile memory such as a flash memory or a RAM, and can store image data corresponding to a plurality of shootings acquired by reading an electrical signal accumulated in the imaging panel 62. is there.

  The wireless communication unit 69 performs wireless communication of various types of information with the console 7 via the access point 5 by a wireless LAN complying with the IEEE 802.11 standard.

  The power supply unit 67 as a battery supplies power to a plurality of drive units (the control unit 64, the imaging panel 62, the storage unit 60, and the like) constituting the FPD 6. The power supply unit 67 includes, for example, a spare battery and a rechargeable battery, and the rechargeable battery can be charged by connecting the connector 695 to a cradle (not shown).

  As shown in FIG. 4, the FPD 6 includes a housing 601 that protects the inside, and is configured to be portable as a cassette. An imaging panel 62 that converts irradiated radiation into an electrical signal is formed in layers inside the housing 601. A light emitting layer 63 that emits light according to the intensity of the incident radiation is provided on the radiation irradiation side of the imaging panel 62.

  The light emitting layer 63 is generally called a scintillator layer. For example, a phosphor is a main component, and an electromagnetic wave having a wavelength of 300 nm to 800 nm based on incident radiation, that is, ultraviolet light centering on visible light. To output electromagnetic waves (light) over infrared light.

  The electromagnetic wave (light) output from the light emitting layer is converted into electric energy and accumulated on the surface opposite to the surface irradiated with radiation of the light emitting layer 63, and an image signal based on the accumulated electric energy. An imaging panel 62 is formed in which photoelectric conversion units that output the above are arranged in a matrix. Note that a signal output from one photoelectric conversion unit is a signal corresponding to one pixel serving as a minimum unit constituting image data. The imaging panel 62 also includes a scanning drive circuit 609 that reads the stored electrical energy, a signal selection circuit 608 that outputs the stored electrical energy as an image signal, and current detection that detects a current corresponding to the radiation dose. Part 634.

  The FPD 6 in this embodiment can detect the start and stop of radiation irradiation by the radiation irradiation device 3 by the current detection unit 634. In the present embodiment, a photodiode is used as the detection element 620, but a phototransistor or the like can also be used. Each detection element 620 is connected to a thin film transistor (hereinafter referred to as TFT) 622 which is a switching element, and is connected to a signal line 624 via the TFT 622.

As shown in FIG. 5, the imaging panel 62 has TFTs 622 (consisting of reference numerals 681, 682, 683, 684a, 684b, 68d, and 68g) made of Al, Cr, or the like on the light receiving side surface 604a of the substrate 604. gate electrode 68g are formed by integrally laminating a scanning line 623, the gate electrode 68g on the gate insulating layer 681 made of the gate electrode 68g and the laminated silicon nitride on the surface 604a (SiN _x), etc. A source electrode 68s connected to the first electrode 674 of the detection element 620 (configured by reference numerals 672 to 679) and a signal through a semiconductor layer 682 made of hydrogenated amorphous silicon (a-Si) or the like in the upper part A drain electrode 68d formed integrally with the line 624 is laminated.

The source electrode 68s and the drain electrode 68d are divided by a first passivation layer 683 made of silicon nitride (SiN _x ) or the like, and the first passivation layer 683 covers both electrodes 68s and 68d from above. In addition, ohmic contact layers 684a and 684b formed in an n-type by doping hydrogenated amorphous silicon with a group VI element are stacked between the semiconductor layer 682 and the source electrode 68s or the drain electrode 68d. The TFT 622 is formed as described above.

  In the detection element 620 portion, an auxiliary electrode 67A is formed by laminating Al, Cr, or the like on the insulating layer 671 formed integrally with the gate insulating layer 681 on the surface 604a of the substrate 604a. A first electrode 674 made of Al, Cr, Mo or the like is laminated on the auxiliary electrode 67A with an insulating layer 673 formed integrally with the first passivation layer 683 interposed therebetween. The first electrode 674 is connected to the source electrode 68 s of the TFT 622 through the hole H formed in the first passivation layer 683.

  On the first electrode 674, an n layer 675 formed into an n-type by doping a group VI element into hydrogenated amorphous silicon, an i layer 676 which is a conversion layer formed of hydrogenated amorphous silicon, and a hydrogenated amorphous A p-layer 677 formed by doping a group III element into silicon and forming a p-type layer is formed by laminating sequentially from below.

  When the electromagnetic wave converted by the light emitting layer 63 that has been irradiated with radiation is irradiated from above in the figure, an electron-hole pair is generated in the i layer 676. In this way, the detection element 620 converts the electromagnetic wave from the light emitting layer 63 into an electric charge. Note that the stacking order of the p layer 677, the i layer 676, and the n layer 675 may be reversed.

  A second electrode 678 made of a transparent electrode such as ITO is laminated on the p layer 677, and the irradiated electromagnetic wave is configured to reach the i layer 676 and the like. The detection element 620 is formed as described above.

A bias line 629 for applying a reverse bias voltage to the detection element 620 is connected to the upper surface of the second electrode 678 of the detection element 620 via the second electrode 678. The second electrode 678 and the bias line 629 of the detection element 620, the first electrode 674 extended to the TFT 622 side, the first passivation layer 683 of the TFT 622, that is, the upper surface portions of the detection element 620 and the TFT 622 are on the upper side. Is covered with a second passivation layer 679 made of silicon nitride (SiN _x ) or the like.

  One end of each electrode of each detection element 620 of the imaging panel 62 is connected to a bias line 629, and each bias line 629 is bound to one connection 630. The connection 630 is connected to the power supply unit 67 via the current detection unit 634. The power supply unit 67 applies a reverse bias voltage to each detection element 620 via each bias line 629.

  In the present embodiment, as can be seen from the fact that the bias line 629 is connected to the p-layer 677 side of the pin-type detection element 620 via the second electrode 678, the power supply unit 67 supplies the first detection element 620. A negative voltage is applied to the two electrodes 678 as a reverse bias voltage via a bias line 629.

  However, as described above, when the p layer 677, the i layer 676, and the n layer 675 of the detection element 620 are formed in the reverse order and the bias line 629 is connected to the n layer 675 via the second electrode 678. From the power source 67, a positive voltage is applied as a reverse bias voltage to the second electrode. In that case, the direction of connection of the detection element 620 to the power supply unit 67 in FIG. 6 is reversed.

  As shown in FIG. 6, the imaging panel 62 includes a plurality of detection elements 620 that convert light into electrical signals, and one detection element 620 corresponds to one pixel of a radiation image. These pixels are arranged at a density of, for example, 200 to 400 dpi (dots per inch) over the size of the imaging region of the subject.

  Further, scanning lines 623 (horizontal lines) and signal lines 624 (vertical lines) are arranged between the detection elements 620, and in the same figure, they are arranged in a grid pattern so that they are orthogonal to each other. Here, assuming that one section surrounded by the scanning line 623 and the signal line 624 is one pixel, the number of pixels of the imaging panel 62 is, for example, m in one direction and n in the other direction. In this case, it is composed of m × n pixels. In the imaging panel 62, detection elements 620 corresponding to the number of m × n pixels and a transistor 622 that is a switching element are arranged, and the scanning line 623 and the signal line 624 are orthogonal to each other between the pixels. Will be disposed.

  The source electrode 68 s of the TFT 622 is connected to the detection element 620, the drain electrode 68 d is connected to the signal line 624, and the gate electrode 68 g is connected to the scanning line 623.

  The first electrode 674 of each detection element 620 is connected to the source electrode 68 s of the TFT 622, and the gate electrode 68 g of each TFT 622 is connected to each scanning line 623 extending from the scanning drive circuit 609. The drain electrode 68d of each TFT 622 is connected to each signal line 624.

  Then, when a signal reading voltage is applied from the scan driving circuit 609 to the gate electrode 68 g of the TFT 8 via the scanning line 623, the gate of the TFT 622 is opened, and the electric charge accumulated in the detection element 620, that is, the electric signal is supplied to the source of the TFT 622. The signal is read out from the drain electrode 68d to the signal line 624 through the electrode 68s.

  The amplifier circuit 603 is provided with a charge reset switch. If the switch is off, a voltage value proportional to the charge accumulated in each detection element 620 is output, and if the switch is on, the voltage is stored. The generated charge is released.

  The imaging panel 62 converts the radiation image into a digital image signal through these circuits. That is, the control unit 64 functioning as an “image data generation unit” supplies a readout signal to each scanning line 623 via the scanning drive circuit 609 to perform image scanning, and captures a digital image signal for each scanning line. Image data is generated by converting a radiographic image into a digital image signal and making it correspond to position information.

  A correlated double sampling circuit 605 (Correlated Double Sampling: hereinafter referred to as CDS) is connected to the output side terminal of the amplifier circuit 603. Here, the correlated double sampling circuit 605 takes the difference between the first voltage value after resetting the capacitor of the charge-voltage conversion circuit and the second voltage value read after imaging (after irradiation). This circuit eliminates (reduces) noise during reset.

[Current detection unit 634]
Next, a procedure for detecting the start and stop of irradiation by the control unit 64 and the current detection unit 634 will be described. In the embodiment shown in FIG. 5, when a negative voltage that is a reverse bias voltage is applied to the second electrode 678 of the detection element 620 via the bias line 629, a potential gradient is generated in the detection element 620. In this state, when radiation is irradiated from a radiation source such as the radiation irradiation device 3 and electromagnetic waves converted from the radiation by the light emitting layer 63 that has received the radiation are incident on the i layer (conversion layer) 676 of the detection element 620, Electron hole pairs are generated in the i layer 676.

  Of the generated electron-hole pairs, the electrons move to the first electrode 674 side having a high potential according to the potential gradient. However, since the gate of the TFT 622 is closed, the electrons are in the first electrode 674 and the i layer 676. In the vicinity of the first electrode 674. Since electron-hole pairs are generated in the i layer 676 of the detection element 620 in proportion to the number of photons of the electromagnetic wave, an amount of electrons corresponding to the amount of incident electromagnetic wave is accumulated in the detection element 620.

  On the other hand, of the generated electron-hole pairs, holes move to the second electrode 678 side having a low potential according to the potential gradient, and flow out to the bias line 629 through the second electrode 678. As shown in FIG. 5, holes flowing out of the detection element 620 and flowing through the bias line 629 are detected by the current detection unit 634 as current.

  The holes flowing through the bias line 629 are also generated by the number of electron-hole pairs generated in proportion to the number of photons of the electromagnetic wave incident on the i layer 676 of the detection element 620. The same amount of holes as the amount of electrons accumulated in the detection element 620 flows in the bias line 629. The current flowing in each bias line 629 and flowing in proportion to the radiation dose is collected in the connection 630 and flows in the connection 630 toward the current detection unit 634.

  Based on the above principle of charge generation in the detection element 620, ideally, in the bias radiation 629 and the connection 630, no current is present in the stage before radiation irradiation in which radiation or electromagnetic waves do not enter the i layer 676 of the detection element 620. In practice, however, a dark current is generated by the detection element 620 and a very small amount of current is detected by the current detection unit 634.

[Detection of irradiation start and stop]
FIG. 7 is a diagram illustrating an example of a temporal change in the voltage value converted from the current and output by the current detection unit 634. As described above, in the present embodiment, the current detection unit 634 converts the current flowing through the connection 630 into a voltage value and outputs the voltage value, so that radiation or electromagnetic waves are not incident on the i layer 676 of the detection element 620 before radiation irradiation. Also, as shown at time ta in FIG. 7, a voltage value Va that is a minute amount but not 0 is input from the current detection unit 634 to the control unit 64.

  When radiation irradiation from the radiation source is started, electron-hole pairs are generated in each detection element 620, and holes are carried to the current detection unit 634 through the bias line 629 and the connection 630. Therefore, as indicated at time tb in FIG. 7, the voltage value V output from the current detection unit 634 increases. Therefore, in the present embodiment, the control unit 64 detects the start of radiation irradiation by detecting that the voltage value V output from the current detection unit 634 has started to increase significantly.

  The start of radiation irradiation due to the increase of the voltage value V may be configured to detect that radiation irradiation has started at time tc when the voltage value V exceeds a predetermined threshold value Vth. It may be configured to detect that radiation irradiation is started at time td when the time differential value exceeds a predetermined threshold value.

  In addition, when irradiation of radiation from the radiation source is completed, generation of electron-hole pairs in each detection element 620 is stopped, and holes are no longer supplied to the bias line 629. Therefore, as shown at time te in FIG. 7, the voltage value V output from the current detection unit 634 starts to decrease. Therefore, in the present embodiment, the control unit 64 detects the end of radiation irradiation by detecting that the voltage value V output from the current detection unit 634 has decreased.

  The end of radiation irradiation due to the decrease in the voltage value V may be configured to detect that the radiation irradiation has ended at the time tf when the voltage value V falls below the predetermined threshold value Vth described above. It is also possible to detect that radiation irradiation has been completed at time tg when the time differential value of V exceeds a predetermined negative value threshold.

[Dose calculation unit]
Since the irradiation amount j is a product of the irradiation time and the irradiation intensity, the detection of the irradiation amount j is performed by using an integration circuit or the like to detect the voltage value V (or from the irradiation start time tc to the irradiation end time tf shown in FIG. It can be calculated by calculating an integral value of a value obtained by subtracting a constant value corresponding to noise from the voltage value V). The calculation may be performed by providing an integration circuit, or by multiplying the irradiation time (tf−tg) by the peak value Vp. In the present embodiment, the control unit 64 functions as an irradiation amount calculation unit by cooperating with the current detection unit 634.

[Synchronization between the radiation irradiation device 3 and the FPD 6 during imaging]
In the FPD 6, a so-called dark current is generated in which charges are generated from the detection element 620 even when radiation is not irradiated. The electric charge generated by this dark current phenomenon becomes noise in obtaining image data and adversely affects the image. In order to reduce the influence of the dark current as much as possible, it is effective to sweep out the electric charge accumulated immediately before photographing. In order to suppress the radiation exposure dose to the patient 12 as much as possible and to suppress the influence of dark current at the same time, the FPD 6 side needs to be synchronized with the irradiation timing of the radiation irradiation device 3 at the time of imaging. The term “synchronization” as used herein refers to (1) discharging the charge of the FPD 6 immediately before radiation irradiation from the radiation irradiation device 3 (charge reset state), and (2) the charge generated in the detection element 620 at the start of radiation irradiation. (3) The reading of the charge accumulated in the detection element 620 is started (charge reading state) when radiation irradiation is stopped.

  Here, each of the “charge reset state”, “charge readout state”, and “charge accumulation state” will be described. The “charge reset state” is a state in which the above-described initialization is continuously performed at a predetermined interval, and the “charge read state” is the charge accumulated in each detection element 620 in turn to the signal line. This is a state in which it is output and converted into a digital image signal via the register 672. The “charge accumulation state” is a state in which each of the charges converted in accordance with radiation irradiation is detected without being initialized or read out. This means a state where the element 620 continues to accumulate, that is, a so-called exposure state.

  The FPD 6 may be synchronized with the radiation irradiation by a signal from an external device such as the console 7. If the current detection unit 634 is provided as in this embodiment, the FPD 6 itself detects irradiation start and stop. May be synchronized.

[Shooting block]
In the present embodiment, the imaging panel 62 shown in FIG. 6 is divided into a plurality of parts. FIG. 8 shows an embodiment of the FPD 6 composed of two photographing blocks, a photographing block 1 and a photographing block 2. As shown in the figure, in the FPD 6, a common signal selection circuit 608, a bias line (630 (1) or 630 (2)) arranged in each imaging block, and a current detection unit (634 (1) or 634 ( 2)), and a scanning drive circuit (609 (1) or 609 (2)). Note that the example shown in FIG. 8 is an example composed of two photographing blocks, but it may be further subdivided and composed of four or more photographing blocks.

  With this configuration, in the present embodiment, the dose j can be calculated for each imaging block by the control unit 64 functioning as the dose calculation unit and the two current detection units 634.

[Control Flow (First Embodiment)]
FIG. 9 is an explanatory diagram of a control flow performed by the radiation image generation system according to the first embodiment. In step S11, the patient 12 is imaged based on the imaging order information to generate image data. In imaging, a radiographer or other photographer sets conditions of irradiation intensity (also referred to as (W / cm ² ) irradiance) and irradiation time of the radiation irradiation device 3 by the imaging operation device 4 based on the imaging order information. Subsequently, by operating an imaging start button (not shown), radiation irradiation is started from the radiation irradiation device 3 based on the set conditions. Prior to the start of radiation irradiation, a notice of notice and an irradiation start notice are transmitted to the FPD 6 via the HUB 9 and the access point 5, and based on these notices, the state of the FPD 6 is “charge reset state”, “charge accumulation state” ”.

  In step S12, an irradiation amount j2 at the time of photographing in step S11 is calculated.

  In step S <b> 13, image data obtained by photographing is transmitted to the console 7. In step S <b> 14, the irradiation amount j <b> 2 of each shooting block obtained at the time of shooting is transmitted to the console 7 by the current detection unit 634 provided in each.

  In step S71, the console 7 displays the image data transmitted from the FPD 6 in step S13 on the display unit 77. In step S72, the photographing block is displayed on the display unit 77 together with the image data. Here, a display example will be described with reference to FIG.

  FIG. 10 shows a display example of the display screen 772 displayed on the display unit 77. In FIG. 10, captured image data is displayed in the image display field 772m. The photographer refers to the image data displayed on the display screen 772 to determine whether the photographer is suitable as a diagnostic image for diagnosing a disease, and determines that the photographer can use the diagnosis and has successfully completed the photographing. In such a case, the shooting is ended by pressing an OK button 772h. On the other hand, if the imaging region is inappropriate or if the imaging is blurred due to the movement of the patient at the time of imaging, the imaging did not end normally and re-imaging is necessary. In such a case, the NG button 772i is pressed. In this case, the imaging order information corresponding to the image data for which the NG button 772i is pressed may be registered again in a predetermined management folder for re-imaging.

  An image processing unit (not shown) performs image processing under optimal image processing conditions (for example, gradation) in accordance with histogram analysis of received image data or in accordance with preset part information. An image processing adjustment field 772e is provided at the upper right of the screen, and the photographer can adjust the density and contrast by operating the image processing adjustment field 772e with a mouse or the like. When the OK button 772h displayed corresponding to each image is pressed, it can be confirmed that the photographing has been completed normally. The display screen 772 is provided with a patient information display field 772f for displaying patient information included in the imaging order information associated with the displayed captured image.

  772p is a block display column 772p indicating the position of the imaging block. In the example shown in the figure, two shooting blocks are displayed. In the display column 772p, it is possible to select an arbitrary number of shooting blocks. The arrangement of the shooting blocks is also superimposed on the image display field 772m, and the rectangular broken line in the image display field 772m corresponds to the arrangement of the two shooting blocks. Since the photographer can recognize that the affected part 12H of the patient is photographed on the lower half of the photographing block 1 side in the image display field 772m, the photographing block 1 is determined as the main region of interest.

In the example shown in the figure, it is shown that the shooting block 1 (lower half) is selected in the block display field 772p. Based on the input of the selection instruction of the selected shooting block by the photographer (step S73), in step S74, the irradiation of the shooting block selected from the irradiation amount j2 of each shooting block transmitted in step S14. The amount j2 is displayed on the display unit 77. In the example of FIG. 10, it can be displayed in the irradiation amount display column 772q. Note that the irradiation dose (J / cm ² ) may be directly displayed as the irradiation amount. As will be described later, the optimal irradiation time is calculated from the optimal irradiation amount j1, the calculated irradiation amount j2, and the irradiation intensity w. Alternatively, the difference irradiation time dt (= (j1-j2) / w) may be obtained and displayed, or the ratio (j2 / j1) between them may be displayed as the feature amount S.

[Control Flow (Second Embodiment)]
FIG. 11 is an explanatory diagram of a control flow performed by the radiation image generation system according to the second embodiment. In the second embodiment, it is determined in advance in which of the imaging blocks the imaging is performed, and the radiation dose is monitored by the imaging block. For example, when the FPD 6 is a cassette that can shoot a half-cut size and performs shooting equivalent to a 4-cut size or a 6-cut size, according to a marker (for example, colored on the end face) on the exterior of the FPD 6 This is a case where the affected part is photographed in the lower half (or the upper half). In this way, the photographer can recognize in which region of the FPD 6 the patient 12 is imaged.

  In step S81 in FIG. 11, an imaging block selection instruction is input by the input operation unit 78 of the console 7. In the example shown in FIG. 10, a selection instruction is given by input to the block display field 772p.

  In step S82, the console 7 transmits the result selected in step S81 to the FPD 6.

  In step S31, radiation irradiation by the radiation irradiation device 3 is started based on an operation instruction to the photographing operation device 4 by the photographer. In step S111, in response to the start of radiation irradiation in step S31, the FPD 6 detects the start of radiation irradiation using its own current detection unit 634. Based on the detection, the detection element 620 is changed to the “charge accumulation state”. Prior to this step, the detection element 620 may be changed to the “charge reset state” based on the selection instruction in step S82 received from the console 7.

  In step S32, the radiation irradiation apparatus 3 stops the radiation irradiation as the set irradiation time elapses. In step S112, the FPD 6 detects the stop by the current detection unit 634. Based on the detection, the detection element 620 is shifted to the “charge reading state”, and the image data generation unit generates image data.

  In step S12, the dose j2 irradiated between steps S111 and S112 is calculated.

  In step S13, the image data obtained in step S112 is transmitted to the console 7. In step S <b> 14, the dose j <b> 2 obtained by the current detector 634 provided in the imaging block corresponding to the selection instruction transmitted in step S <b> 82 is transmitted to the console 7.

  The console 7 displays the image data and the dose j2 on the display unit 77 (steps S83 and S84).

  In step S85, the difference irradiation time dt (= (j1-j2) / w) as a difference from the optimum irradiation time is obtained from the optimum irradiation amount j1, the calculated irradiation amount j2, and the irradiation intensity w, and displayed. . The optimum dose j1 is an optimum dose that does not cause density under and over, and is basically a value determined by the sensitivity characteristics of the FPD 6 used for photographing. The optimum irradiation amount j1 is stored in advance in the storage unit 60 of the FPD 66 or the storage unit 70 of the console 7 together with the identification ID of the FPD 6. Further, since the optimum dose j1 may vary depending on the affected part of the photographing or the degree of obesity of the patient, a converted value obtained by multiplying a predetermined coefficient based on the photographing order information may be used. The reason why the difference irradiation time dt is displayed is that the setting of the irradiation time is easily reflected in the adjustment of the irradiation amount, and it is easy for the photographer to optimize the irradiation time in the subsequent shooting.

  Conventionally, since the irradiation amount obtained by direct irradiation in which the FPD detection element is directly irradiated without passing through the subject is also used, the detection value is output at a high level, and as a result, the subject is photographed. Even if the irradiation dose is insufficient in the imaging region, there is a possibility that detection may occur if it is appropriate.

  According to the first and second embodiments, the imaging panel is divided into a plurality of shooting blocks, and a dose can be detected for each shooting block. By displaying, it is possible to appropriately detect the irradiation amount by using the detection value of the irradiation amount of the imaging region excluding direct irradiation, and to provide the photographer with the information.

[Control Flow (Third Embodiment)]
FIG. 12 is an explanatory diagram of a control flow performed by the radiation image generation system according to the third embodiment. In the third embodiment, the irradiation stop of the radiation irradiation device 3 is controlled based on the detection of the irradiation amount of the FPD 6.

  The control common to FIG. 11 is replaced with the description by attaching the same reference numeral. In step S21, based on the selection instruction transmitted in step S82, the current detection unit 634 corresponding to the selected imaging block is validated and the dose j is monitored. In step S22, the radiation irradiation started in step S31 is detected. The detection of the start of irradiation is preferably performed by the current detection unit 634 of the selected imaging block, but may be performed by the output of the current detection unit 634 of another imaging block that is not selected.

  In step S23, it is monitored whether the monitored dose j exceeds the optimum dose j1. If it is determined that it has been exceeded (step S23: Yes), an irradiation stop notification is transmitted to the console 7 (step S24). The console 7 that has received the notification notifies the radiation irradiation apparatus of a stop instruction (step S825). Note that the FPD 6 may directly instruct the photographing operation device 4.

  In step S32, based on the notification, the radiation irradiation apparatus 3 stops radiation irradiation. Since the control after step S112 is the same as that in FIG.

  In the present embodiment, since the irradiation stop of the radiation irradiation apparatus 3 is controlled based on the irradiation amount j of the selected imaging block, the detection value of the irradiation amount is used in an imaging region in which the influence of direct irradiation is avoided as much as possible. Thus, the irradiation amount can be appropriately detected and the radiation irradiation apparatus 3 can be controlled.

DESCRIPTION OF SYMBOLS 3 Radiation irradiation apparatus 4 Image pick-up operation apparatus 5 Access point N Network 11 Position imaging stand 6 Radiation image detection apparatus 62 Imaging panel 63 Light emitting layer 64 Control part 60 Memory | storage part 67 Power supply part 69 Wireless communication part 608 Signal selection circuit 609 Scanning drive circuit 620 Detection element 623 Scan line 629 Bias line 630 Connection 634 Current detection unit 7 Console 70 Storage unit 74 Control unit 77 Display unit 78 Input operation unit 79 Communication unit

Claims (7)

A radiation irradiation device;
An imaging panel in which a plurality of detection elements that convert energy corresponding to an irradiation amount irradiated from the radiation irradiation apparatus and transmitted through the subject into a charge amount are arranged in a matrix;
An image data generation unit that generates image data from the amount of charge obtained by the detection element;
A plurality of bias lines for supplying a reverse bias voltage to the detection elements in each imaging block as a plurality of imaging blocks as detection elements of the imaging panel;
A power supply for applying a reverse bias voltage to the detection element via the bias line;
A current detection unit for detecting a current flowing through each of the bias lines;
An input unit for inputting an instruction to select at least one shooting block from the plurality of shooting blocks by the photographer;
A radiation image generation system comprising: an irradiation amount calculation unit that calculates an irradiation amount irradiated on at least a selected imaging block based on a detection value by the current detection unit. A control device including the input unit and a display unit;
The radiation image generation system according to claim 1, wherein an irradiation amount of the selected imaging block is displayed on the display unit.   The radiographic image generation system according to claim 2, wherein the control device displays the generated image data on the display unit together with position information of the imaging block.   The control device calculates a difference irradiation time with respect to an appropriate irradiation time based on the optimum radiation dose j1 of the imaging panel and the dose j2 of the selected imaging block, and the difference irradiation time is displayed on the display unit. The radiation image generation system according to claim 2, wherein the radiation image generation system is displayed.   The detection of the radiation detection to the said imaging panel by detection of the said electric current detection part is detected, Based on this detection, the said detection element is changed to an electric charge accumulation state, Any one of Claim 1 to 4 characterized by the above-mentioned. A radiographic image generation system according to claim 1. An imaging panel in which a plurality of detection elements that convert energy corresponding to the amount of irradiation irradiated from the radiation irradiation apparatus and transmitted through the subject into a charge amount are arranged in a matrix;
An image data generation unit that generates image data from the amount of charge obtained by the detection element;
A plurality of bias lines for supplying a reverse bias voltage to the detection elements in each imaging block as a plurality of imaging blocks as detection elements of the imaging panel;
A power supply for applying a reverse bias voltage to the detection element via the bias line;
A current detection unit for detecting a current flowing through each of the bias lines;
An irradiation amount for calculating an irradiation amount irradiated on the basis of a detection value by the current detection unit for at least a selected shooting block in response to a selection instruction for selecting at least one shooting block from the plurality of shooting blocks by a photographer A radiation image detection apparatus comprising a calculation unit.   The radiological image detection apparatus according to claim 6, wherein the detection of the radiation is started by detection of the current detection unit, and the detection element is changed to a charge accumulation state based on the detection.

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