JP2015226605A - Radiation detection system and radiation detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation detection system and a radiation detection method which can stably detect a radiation with less temporal delay from irradiation start to detection start of the radiation, and can reduce power consumption of a radiation detector.SOLUTION: A radiation detection system 10 comprises an X-ray source 11, a transmitter 13, a receiver 14 and a flat panel detector 12. The X-ray source 11 emits an X-ray 22. The transmitter 13 transmits a radio signal at least corresponding to irradiation start of the X-ray 22 from the X-ray source 11. The receiver 14 receives the radio signal transmitted from the transmitter 13. The flat panel detector 12 starts detection of the X-ray 22 on the basis of the radio signal at least corresponding to irradiation start of the X-ray 22 from the X-ray source 11 received by the receiver 14.

Description

  Embodiments described herein relate generally to a radiation detection system and a radiation detection method for detecting radiation.

  Conventionally, X-ray image detection apparatuses using a flat panel detector (hereinafter referred to as FPD) using a semiconductor element such as a TFT as a radiation detection apparatus are widely used in radiography, for example, X-ray imaging. In the FPD, a plurality of pixels that accumulate charges according to the amount of incident X-rays are arranged vertically and horizontally, and digital image data can be obtained by converting X-rays into voltage signals at these pixels. .

  The FPD has a feature that noise caused by the dark current from the electronic circuit is accumulated in the TFT, so that the charge needs to be refreshed at regular intervals, unlike the film and the imaging plate. For this reason, in order to obtain an image with less noise, it is necessary to determine the start and end timings of taking in charge of a pixel in a certain time even in X-ray imaging.

  In recent years, wireless FPDs equipped with batteries and without cables have become widespread due to their high convenience. However, because of their wireless characteristics, X-ray irradiation start and end can be exchanged with X-ray generators. The FPD itself does not carry out by wire, but can automatically detect X-rays and obtain image data.

  In order for the FPD to automatically detect X-rays and obtain a digital image, it is necessary to detect the start of irradiation within a few ms after the X-rays are bombarded, and to quickly start capturing charges from the pixels. For that purpose, it is necessary to capture X-rays from a minute state immediately after X-rays are generated. As the method, there is a method of using a part of pixels of the TFT array for detection. Furthermore, a method of determining that X-ray irradiation starts when a threshold value is set and a signal exceeding a certain level is obtained is common. At this time, there is a device to capture minute changes by increasing the amplification factor (gain) of the amplifier when reading the output signal of the pixel, but the influence of the dark current of the circuit mentioned above, other vibrations and shocks, etc. There is also a problem that causes false detection because there is noise due to the above and it is greatly affected by these.

  In addition, when detecting the start of irradiation, there is a method in which signal readout from pixels is repeatedly performed and irradiation is started when the signal becomes larger than a threshold value.

  Alternatively, in order to prevent erroneous detection, the amplification factor of the amplifier when reading out the pixel output signal is set to two types of high gain and low gain, primary determination at high gain, secondary determination at low gain, and secondary determination. There is also a method for detecting the start of irradiation so as not to impair the accumulation of charges due to X-ray irradiation even during the determination.

  In addition, a CMOS element that can be read in real time may be used for the X-ray irradiation detection portion, instead of the TFT that clears the charge every time it is read. Although detection is faster than TFT, there is a problem of increased cost due to increased functions.

  The above method is common as a method of starting detection after receiving X-rays, and there is inevitably a time delay from the start of X-ray irradiation to the start of detection. In addition, since the signal passing through the subject is used for detection, variations in X-ray transmission and scattering occur depending on the size and arrangement of the subject, resulting in a deviation in the timing of starting detection and a risk of erroneous detection. In that case, it is necessary to set the X-ray dose more than necessary or to perform imaging again, which increases the burden on the patient and the technician. Further, the obtained digital X-ray image also has a large variation in image quality.

  In the state where the FPD is waiting for X-ray irradiation detection, more electric power is used during standby in order to detect the amount of change in the TFT charge. Since the wireless FPD is driven by a battery, it is not preferable that the battery is consumed quickly.

JP 2003-126072 A JP2013-98796A

  When the FPD detects X-rays, a time delay from the start of X-ray irradiation to the start of detection cannot be avoided, and the X-rays to be detected pass through and scatter through the subject and reach the FPD. The detection start timing varies, and the image quality of the obtained image data varies greatly. In addition, the power consumed by the FPD during standby for detecting X-rays increases.

  A problem to be solved by the present invention is a radiation detection system and a radiation detection method capable of detecting a stable radiation with little time delay from the start of radiation irradiation to the start of detection and reducing the power consumption of the radiation detection apparatus. Is to provide.

  The radiation detection system of the present embodiment includes a radiation generator that emits radiation, a transmitter that transmits at least a radio signal corresponding to the start of radiation irradiation from the radiation generator, and a radio signal transmitted by the transmitter. A receiving device for receiving, and a radiation detecting device for starting detection of radiation based on a radio wave signal corresponding to the start of radiation irradiation from at least the radiation generating device received by the receiving device.

It is a perspective view of the radiation detection system which shows one Embodiment. It is a graph which shows the relationship between the intensity | strength of X-rays irradiated to the radiation detection apparatus of a radiation detection system same as the above, and time.

  Hereinafter, an embodiment will be described with reference to FIGS. 1 and 2.

  FIG. 1 shows a radiation detection system 10. The radiation detection system 10 includes an X-ray source 11 as a radiation generation device, a flat panel detector (hereinafter referred to as FPD) 12 as a radiation detection device, a transmission device 13 that transmits a radio signal, and a reception device that receives a radio signal. It has 14 mag.

  The X-ray source 11 includes, for example, a cathode (filament) 20 and a rotating anode 21, and generates X-rays 22 as radiation by colliding electrons emitted from the cathode 20 with the rotating anode 21. Let The generated X-rays 22 are emitted from the window 23 to the outside, pass through and scatter through the subject 24, and irradiate the FPD 12.

  The X-ray source 11 is electrically connected to the controller 25 by a cable 26 and receives a signal from the controller 25 to generate an X-ray 22. In the case of the portable X-ray source 11, the X-ray source 11 and the controller 25 may be disposed in the same casing.

  In addition, the transmission device 13 transmits a radio wave signal corresponding to the start of irradiation of the X-rays 22 in accordance with either energization of the cathode 20 or rotation of the anode 21. For example, in order to generate X-rays 22, a voltage is applied from the controller 25 to the cathode 20 of the X-ray source 11 and energized. A radio signal indicating the start of irradiation of the line 22 is transmitted. Alternatively, a voltage is applied to the starter to rotate the anode 21 from the controller 25 before the X-ray 22 is irradiated to generate the X-ray 22, but a part of the voltage is also applied to the transmitter 13 as a signal. Then, a radio wave signal is transmitted to notify the FPD 12 of the start of X-ray irradiation. In addition to transmission of radio signals corresponding to the start of irradiation of X-rays 22, in addition to radio signals instructing to turn on / off the power of the FPD 12 and mode switching such as switching to a standby mode with low power consumption, for example, the FPD 12 You may transmit the radio signal to instruct | indicate, respectively.

  In the present embodiment, an example in which the transmission device 13 is incorporated in the X-ray source 11 in advance is shown. However, the transmission device 13 may be incorporated in the controller 25 in advance, or may be added or externally added to the X-ray source 11 or the controller 25 later. Further, for example, in the actual usage method of the transmission device 13, the transmission device 13 is installed in the power distribution system of the controller 25 of the X-ray source 11, and the voltage signal is sent to the transmission device 13 when the voltage to the X-ray source 11 is applied. And a method of applying a voltage signal to the transmitter 13 by detecting a voltage applied to the cathode 20 by a detection circuit incorporated in the X-ray source 11. At this time, the voltage signal to the transmitter 13 is preferably in the range of 3V to 30V.

  In the FPD 12, a plurality of pixels each having a semiconductor element such as a TFT are arranged in a matrix in the vertical and horizontal directions. Charges corresponding to the amount of incident X-rays 22 are accumulated in these pixels and converted into voltage signals. Thus, digital image data can be obtained.

  The FPD 12 includes a battery 30 as a power source and is portable. Further, the FPD 12 includes a control unit that controls the FPD 12 and a communication unit that transmits the obtained image data to a wireless LAN access point by Wifi (registered trademark) communication, for example.

  In addition, the reception device 14 receives the radio signal transmitted from the transmission device 13 and sends it to the control unit of the FPD 12.

  The receiving device 14 may be shared with the communication unit because the FPD 12 includes a communication unit for transmitting image data. In the present embodiment, the receiving device 14 is incorporated in the FPD 12 in advance. However, the receiving device 14 may be added to or attached to the FPD 12 later.

  In addition, the radio wave transmitted from the transmission device 13 and received by the reception device 14 has a usable frequency that complies with local laws and regulations, and it is difficult for peripheral devices to malfunction, and the reception device 14 itself malfunctions. It is set to be less likely.

  In the radiation detection system 10 configured as described above, the transmission device 13 transmits a radio signal in synchronization with the irradiation start timing of the X-ray 22 from the X-ray source 11, and the reception device 14 receives the radio signal. Then, the irradiation start of the X-ray 22 is determined, and the FPD 12 starts taking in charges from the pixel, that is, the FPD 12 starts detecting the X-ray 22.

  If this radio signal exchange method is carried out, the radio wave signal at the start of irradiation is always transmitted from the transmission device 13 in accordance with the irradiation of the X-ray 22 from the X-ray source 11. Therefore, the FPD 12 uses the X-ray 22 based on the radio signal. Detection of X-rays 22 is less likely to occur. The timing at which the FPD 12 starts taking in the charge of the pixel is also constant. As a result, unnecessary exposure to patients and technicians can be reduced, and the obtained digital image data has high quality with little variation.

  FIG. 2 shows the relationship between the relative intensity of the X-ray 22 irradiated to the FPD 12 and time.

  In a general X-ray 22 automatic detection method, the FPD 12 starts to take in charge of a pixel when a threshold value a for detecting the intensity of the X-ray 22 is exceeded. Since the threshold value a for detecting the intensity of the X-ray 22 needs to prevent erroneous detection due to the influence of noise or the like, it cannot be set to a very small value. As a result, the X-ray 22 up to the time t2 necessary for the automatic detection of the X-ray 22 cannot be used, and the X-ray 22 can be detected from the time t3 when the FPD 12 operates effectively.

  In the present embodiment, the FPD 12 can start taking in the charge of the pixel at time t1 in synchronization with the timing when the X-ray source 11 starts irradiating the X-ray 22, and the detection delay of the X-ray 22 can be reduced. .

  It should be noted that there is a slight time lag between the reception of the radio wave of the transmission device 13 by the reception device 14 and the start of taking in the charge of the pixel, and it is assumed that the detection is delayed with respect to the start of irradiation of the X-ray source 11. In this case, however, the time lag can be reduced by setting the time difference for transmitting signals to the transmitter 13 and the X-ray source 11 by the controller 25 of the X-ray source 11 in consideration of the reaction time difference. .

  From the viewpoint of energy saving, the FPD 12 allows the controller 25 to switch the power of the FPD 12 on / off and the standby mode of the FPD 12 to a mode with less power consumption based on the radio signal transmitted from the transmitter 13. May be.

  For example, if both the voltage applied to the starter for rotating the anode 21 and the voltage applied to the cathode 20 of the X-ray source 11 can be monitored, the X-ray source 11 immediately before the X-ray 22 is bombarded. After the FPD 12 is turned on, image data acquisition is started immediately thereafter, and after the image data is transmitted from the FPD 12, the FPD 12 can be turned off. Can be built.

  Even if this is not switching the power supply of the FPD 12 on and off, a similar effect can be obtained even when shifting to a mode with less standby power.

  An implementation method in which the transmitter 13 is incorporated in the product as a function at the time of manufacturing the X-ray source 11, an implementation method in which the transmitter 25 is provided in the controller 25 of the X-ray source 11 when the radiation detection system 10 is installed, or a conventional method It is also possible to implement an existing X-ray source 11 when upgrading from a cassette or imaging plate to digitization.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

10 Radiation detection system
11 X-ray source as a radiation generator
12 Flat panel detector as a radiation detector
13 Transmitter
14 Receiver
20 cathode
21 Anode
22 X-rays as radiation

Claims (6)

A radiation generator for emitting radiation;
A transmission device that transmits at least a radio signal corresponding to the start of radiation irradiation from the radiation generation device;
A receiving device for receiving a radio signal transmitted by the transmitting device;
A radiation detection system comprising: a radiation detection device that starts detection of radiation based on a radio wave signal corresponding to at least radiation start of radiation from the radiation generator received by the reception device. The radiation generator has a cathode for generating radiation and a rotating anode.
The transmission device transmits a radio wave signal corresponding to the start of radiation irradiation from the radiation generation device in accordance with any one of energization to the cathode and rotation start of the anode. The radiation detection system described. The transmission device transmits a radio signal of any one of the switching of the power source and the mode of the radiation detection device,
The radiation detection apparatus executes either one of power supply switching and mode switching of the radiation detection apparatus based on a radio signal of either power switching or mode switching received by the receiving apparatus. The radiation detection system according to claim 1 or 2. The transmitting device transmits a radio signal corresponding to at least radiation start from the radiation generating device,
The receiving device receives the radio signal transmitted from the transmitting device,
The radiation detection method, wherein the radiation detection device starts detection of radiation based on at least a radio wave signal received by the reception device corresponding to the start of radiation irradiation from the radiation detection device. The radiation generating device has a cathode for generating radiation and a rotating anode, and starts irradiation of radiation from the radiation generating device in accordance with either energization of the cathode or rotation of the anode. 5. The radio wave detection method according to claim 4, wherein a corresponding radio signal is transmitted. The radiation generating device transmits a radio signal of either one of the switching of the power source and the mode of the radiation detecting device,
5. The radiation detection apparatus executes either one of power supply switching and mode switching based on a radio signal of either power switching or mode switching received by the receiving apparatus. Or the radiation detection method of 5.

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