CN114740522A - Direct X-ray flat panel detector and exposure synchronization method - Google Patents

Abstract

The invention discloses a direct X-ray flat panel detector and an exposure synchronization method, which are applied to the field of X-ray flat panel detectors. The direct detection area array includes a plurality of pixels distributed in an array, and the pixels include thin film transistors and are electrically connected to the thin film transistors. The direct semiconductor; the direct semiconductor is electrically connected with a bias signal line, and the bias signal line is used to apply a preset bias voltage to both ends of the direct semiconductor; the bias signal line is connected to the processor through the current comparison module, and the current comparison The module is used to send a trigger signal to the processor when the current in the bias signal line is greater than the current threshold; the processor is used to collect and directly detect the actual image generated by the area array according to the trigger signal. When the direct X-ray flat panel detector receives X-rays, it will directly reflect the current flowing in the bias signal line. Accurate exposure synchronization can be achieved by detecting the current in the bias signal line, and performing exposure according to the moment when the current changes as a trigger signal.

Description

A direct X-ray flat panel detector and exposure synchronization method

technical field

The invention relates to the field of X-ray flat panel detectors, in particular to a direct X-ray flat panel detector and an exposure synchronization method for the direct X-ray flat panel detector.

Background technique

A digital X-ray imaging system consists of an X-ray source and a detector. The image acquisition of the detector needs to be synchronized with the exposure of the X-ray source. This synchronization can be realized by the wired connection between the generator of the X-ray source and the detector, but this wired connection is usually very inconvenient and can only be implemented by professional technicians after understanding the interface design of the generator and the detector. Sometimes the generator is not yet able to provide this connection. Therefore, various automatic exposure synchronization functions have appeared on the market, that is, the detector does not have any physical connection with the generator, but the detector can detect the exposure of X-rays by different methods, and start the detector's exposure in a short time. Image acquisition to achieve automatic exposure synchronization.

At present, the existing automatic exposure synchronization solutions on the market are mainly to install an independent X-ray detector in the detector to detect the exposure of X-rays. In practice, due to space and cost constraints, the independent X-ray detectors are usually small and can only detect local X-rays. If the X-rays are only incident on a partial area of the detector, there is a possibility that the independent X-ray detectors will not be launched, thereby invalidating the exposure synchronization. Since the independent X-ray detector needs to be installed behind the photoelectric detection area array, the X-ray signal has been largely absorbed by the scintillator, so the detection sensitivity of the independent X-ray detector will be limited. For thicker scintillators or weaker X-rays, the sensitivity of stand-alone X-ray detectors is often not sufficient for the application. For an independent X-ray detector that detects visible light generated by X-rays passing through a scintillator, it is generally necessary to open a window to the detector support structure. Both will lead to uneven distribution of the structure behind the photoelectric detection area array and backscattering phenomenon, which will cause image artifacts to a certain extent.

Therefore, how to achieve accurate exposure synchronization of the direct X-ray flat panel detector is an urgent problem to be solved by those skilled in the art.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a direct X-ray flat panel detector, which can achieve accurate exposure synchronization; another purpose of the present invention is to provide a direct X-ray flat panel detector exposure synchronization method, which can achieve accurate exposure synchronization .

In order to solve the above technical problems, the present invention provides a direct X-ray flat panel detector, which includes a direct detection area array, a current comparison module and a processor;

The direct detection area array includes a plurality of pixels distributed in an array, and the pixels include a thin film transistor and a direct semiconductor electrically connected to the thin film transistor; the direct semiconductor is electrically connected with a bias signal line, and the bias The voltage signal line is used to apply a preset bias voltage to both ends of the direct semiconductor;

The bias signal line is connected to the processor through the current comparison module, and the current comparison module is configured to send a trigger signal to the processor when the current in the bias signal line is greater than a current threshold;

The processor is configured to acquire the actual image generated by the direct detection area array according to the trigger signal.

Optionally, the material of the direct semiconductor includes:

Amorphous selenium, monocrystalline silicon, high-purity germanium, cadmium zinc telluride, cesium lead bromine, mA lead iodine.

Optionally, the direct semiconductor thickness ranges from 100 μm to 1000 μm, inclusive.

Optionally, the pixel further includes a storage capacitor, and the storage capacitor is connected in parallel with the direct semiconductor.

Optionally, the output end of the thin film transistor is connected with a data line, and the data line is connected with a sense amplifier.

Optionally, all the bias signal lines are connected to the same bias signal bus; the bias signal bus is connected to the processor through the current comparison module.

Optionally, the current comparison module includes an operational amplifier, and an output end of the operational amplifier is connected to the processor.

Optionally, the processor is an FPGA.

The present invention also provides a direct X-ray flat panel detector exposure synchronization method, applied to the processor, including:

The images generated by the direct detection area array are collected at equal intervals; the direct detection area array includes a plurality of pixels distributed in an array, and the pixels include thin film transistors and direct semiconductors electrically connected to the thin film transistors; the The direct type semiconductor is electrically connected with a bias voltage signal line, and the bias voltage signal line is used for applying a preset magnitude of bias voltage to both ends of the direct type semiconductor;

acquiring a trigger signal sent by a current comparison module; the trigger signal is a signal generated by the current comparison module when the current in the bias signal line is greater than a current threshold;

The actual image is determined from the image according to the trigger signal.

Optionally, the determining the actual image from the image according to the trigger signal includes:

determining an original image and a background image from the image according to the trigger signal;

The actual image is obtained by subtracting the background image from the original image.

A direct X-ray flat panel detector provided by the present invention includes a direct detection area array, a current comparison module and a processor; the direct detection area array includes a plurality of pixels distributed in an array, and the pixels include thin film transistors and electric currents connected to the thin film transistors. The direct semiconductor is connected; the direct semiconductor is electrically connected with a bias signal line, and the bias signal line is used to apply a bias voltage of a preset magnitude to both ends of the direct semiconductor; the bias signal line is connected to the processor through the current comparison module, and the current The comparison module is used to send a trigger signal to the processor when the current in the bias signal line is greater than the current threshold; the processor is used to collect and directly detect the actual image generated by the area array according to the trigger signal.

When the direct-type X-ray flat panel detector receives X-rays, the direct-type semiconductor will directly generate sub-hole signals according to the received X-rays to form a current, which directly reflects the current flowing in the bias signal line. Accurate exposure synchronization can be achieved by detecting the current in the bias signal line, and performing exposure according to the moment when the current changes as a trigger signal.

The present invention also provides a method for synchronizing exposure of a direct X-ray flat panel detector, which also has the above beneficial effects, and will not be repeated here.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following will briefly introduce the accompanying drawings used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only For some embodiments of the present invention, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

1 is a schematic structural diagram of a direct X-ray flat panel detector according to an embodiment of the present invention;

Fig. 2 is the control circuit diagram of the direct X-ray flat panel detector in Fig. 1;

Fig. 3 is the enlarged structural schematic diagram of the pixel in Fig. 1;

4 is a flowchart of a method for synchronizing exposure of a direct X-ray flat panel detector provided by an embodiment of the present invention;

Figure 5 is an image acquisition sequence diagram;

6 is a flowchart of a specific method for synchronizing exposure of a direct X-ray flat panel detector provided by an embodiment of the present invention;

Fig. 7 is the timing chart of the interval time acquisition trigger signal;

FIG. 8 is a timing diagram for acquiring a trigger signal at acquisition time.

In the figure: 1. Direct detection area array, 2. Thin film transistor, 3. Direct semiconductor, 4. Bias voltage signal line, 5. Bias voltage signal bus, 6. Current comparison module, 7. Processor, 8. Storage capacitor .

Detailed ways

The core of the present invention is to provide a direct X-ray flat panel detector. In the prior art, it is common to install an independent X-ray detector to detect X-ray exposure. In practice, due to space and cost constraints, the independent X-ray detectors are usually small and can only detect local X-rays. If the X-rays are only incident on a partial area of the detector, there is a possibility that the independent X-ray detectors will not be launched, thereby invalidating the exposure synchronization. Since the independent X-ray detector needs to be installed behind the photoelectric detection area array, the X-ray signal has been largely absorbed by the scintillator, so the detection sensitivity of the independent X-ray detector will be limited. For thicker scintillators or weaker X-rays, the sensitivity of stand-alone X-ray detectors is often not sufficient for the application. For an independent X-ray detector that detects visible light generated by X-rays passing through a scintillator, it is generally necessary to open a window to the detector support structure. Both will lead to uneven distribution of the structure behind the photoelectric detection area array and backscattering phenomenon, which will cause image artifacts to a certain extent.

The direct X-ray flat panel detector provided by the present invention includes a direct detection area array, a current comparison module and a processor; the direct detection area array includes a plurality of pixels distributed in an array, and the pixels include thin film transistors and thin film transistors. The direct semiconductor is electrically connected; the direct semiconductor is electrically connected with a bias signal line, and the bias signal line is used to apply a preset bias voltage to both ends of the direct semiconductor; the bias signal line is connected to the processor through the current comparison module, The current comparison module is used to send a trigger signal to the processor when the current in the bias signal line is greater than the current threshold; the processor is used to collect and directly detect the actual image generated by the area array according to the trigger signal.

When the direct-type X-ray flat panel detector receives X-rays, the direct-type semiconductor will directly generate sub-hole signals according to the received X-rays to form a current, which directly reflects the current flowing in the bias signal line. Accurate exposure synchronization can be achieved by detecting the current in the bias signal line, and performing exposure according to the moment when the current changes as a trigger signal.

In order to make those skilled in the art better understand the solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Please refer to FIG. 1 and FIG. 2 , FIG. 1 is a schematic structural diagram of a direct X-ray flat panel detector according to an embodiment of the present invention; FIG. 2 is a control circuit diagram of the direct X-ray flat panel detector in FIG. 1 .

Referring to FIG. 1 and FIG. 2 , in the embodiment of the present invention, the direct X-ray flat panel detector includes a direct detection area array 1 , a current comparison module 6 and a processor 7 ; the direct detection area array 1 includes a plurality of a pixel, the pixel includes a thin film transistor 2 and a direct semiconductor 3 electrically connected to the thin film transistor 2; the direct semiconductor 3 is electrically connected with a bias signal line 4, and the bias signal line 4 is used to send signals to A bias voltage of a preset magnitude is applied to both ends of the direct semiconductor 3; the bias voltage signal line 4 is connected to the processor 7 through the current comparison module 6, and the current comparison module 6 is used when the bias voltage When the current in the signal line 4 is greater than the current threshold, a trigger signal is sent to the processor 7 ; the processor 7 is configured to collect the actual image generated by the direct detection area array 1 according to the trigger signal.

The above-mentioned direct detection area array 1 is the main structure of the direct X-ray flat panel detector for acquiring X-ray exposure images. The direct detection area array 1 usually includes a plurality of pixels, and the plurality of pixels are usually distributed in an array. In the embodiment of the present invention, each pixel is generally provided with a thin film transistor 2 (TFT) and a direct type semiconductor 3, ie, a direct type photoconductor (PD). In the embodiment of the present invention, the direct semiconductor 3 can directly absorb X-rays and generate electron-hole pairs, that is, the direct semiconductor 3 can directly convert the energy of the absorbed X-rays into electrical energy. When X-rays irradiate a certain pixel in the direct detection area array 1, the direct semiconductor 3 in the pixel can directly react to generate a corresponding electrical signal. The remaining structures related to the direct detection area array 1 can be set by themselves according to the actual situation, and will not be repeated here.

Specifically, in the embodiment of the present invention, the material of the direct semiconductor 3 includes: amorphous selenium, single crystal silicon, high-purity germanium, cadmium zinc telluride, cesium lead bromine, and mA lead iodine. Among them, mA lead iodine is iodine lead methylamine. The material of the direct semiconductor 3 is not specifically limited in the embodiments of the present invention, as long as it can directly absorb X-rays, convert them into electrical energy, and generate electron-hole pairs. It should be noted that, since the X-ray flat panel detector provided by the embodiment of the present invention is a direct X-ray flat panel detector, the conversion process of visible light to electron-hole pairs is reduced compared with the indirect detector, which makes the image noise Smaller and sharper images.

The above-mentioned thin film transistor 2 connected to the direct semiconductor 3 is mainly used to realize the control of each pixel in the direct detection area array 1. The above-mentioned direct semiconductor 3 is usually connected to the input end of the thin film transistor 2, and the gate of the thin film transistor 2 is connected. Usually, it is electrically connected to the gate driving circuit through the gate line, so as to realize the control of each pixel by the gate driving circuit.

The above-mentioned direct type semiconductor 3 is electrically connected with a bias voltage signal line 4 , and the bias voltage signal line 4 is generally used to apply a predetermined magnitude of bias voltage to both ends of the direct type semiconductor 3 . In the embodiment of the present invention, the purpose of applying a predetermined magnitude of bias voltage to both ends of the direct semiconductor 3 is to better collect electron-hole pairs generated by the direct semiconductor 3 due to X-rays. Therefore, under the driving of the bias voltage, when no X-rays are received, the direct semiconductor 3 and its circuits will also generate a certain leakage current, forming a background signal without X-rays. When the direct semiconductor 3 receives X-rays, the leakage current will increase, so that the signal current will also be superimposed on the background signal.

In the embodiment of the present invention, the bias signal line 4 is specifically connected to the current comparison module 6 , and the current comparison module 6 is connected to the processor 7 , that is, the bias signal line 4 is connected to the processor 7 through the current comparison module 6 . The current comparison module 6 can be used to monitor the change of the current flowing in the bias signal line 4, and then can send a trigger signal to the processor 7 when the current in the bias signal line 4 is greater than the current threshold. The specific setting of the above-mentioned current threshold needs to be set by itself according to the actual situation, which is not specifically limited here. The specific content of the above trigger signal is not specifically limited, and it depends on the specific situation.

In the embodiment of the present invention, the processor 7 will receive the trigger signal sent by the current comparison module 6, and the processor 7 will be specifically configured to collect the image generated by the direct detection area array 1 according to the trigger signal, for exposure synchronization. The specific content of acquiring an image generated by the direct detection area array 1, that is, performing exposure, will be described in detail in the following invention embodiments, and will not be repeated here. Specifically, in the embodiment of the present invention, the above-mentioned processor 7 may be an FPGA (Field Programmable Gate Array, Field Programmable Gate Array), and based on the characteristic of parallel processing of the FPGA, exposure can be performed in time in response to the above-mentioned trigger signal.

Specifically, in the embodiment of the present invention, generally all the bias signal lines 4 are connected to the same bias signal bus 5 ; the bias signal bus 5 is connected to the processor 7 through the current comparison module 6 . That is, the bias signal lines 4 connecting the direct semiconductors 3 will pass through the same point, so that the bias voltages of all the direct semiconductors 3 are provided through a single line, that is, provided through the bias signal bus 5, so that the detection circuit can be simplified. The comparison module 6 judges whether each pixel receives an image in time. In the embodiment of the present invention, the port for supplying current to the bias signal bus 5 is generally referred to as Vbias.

Generally, the above current comparison module 6 includes an operational amplifier, and the output end of the operational amplifier is connected to the processor 7 . Since the current change in the bias signal line 4 or the bias signal bus 5 is usually small, in the embodiment of the present invention, the leakage current is amplified by the operational amplifier, and then it is determined whether the change of the leakage current meets the condition, that is, Whether the current in the bias signal line 4 is greater than the current threshold. Only when the current in the bias signal line 4 is greater than the current threshold, will a trigger signal be sent to the processor 7 through the output terminal of the operational amplifier.

A direct X-ray flat panel detector provided by an embodiment of the present invention includes a direct detection area array 1, a current comparison module 6 and a processor 7; the direct detection area array 1 includes a plurality of pixels distributed in an array, and the pixels include a thin film The transistor 2 and the direct semiconductor 3 electrically connected to the thin film transistor 2; the direct semiconductor 3 is electrically connected with a bias signal line 4, and the bias signal line 4 is used to apply a bias voltage of a preset size to both ends of the direct semiconductor 3; The bias signal line 4 is connected to the processor 7 through the current comparison module 6, and the current comparison module 6 is used for sending a trigger signal to the processor 7 when the current in the bias signal line 4 is greater than the current threshold; the processor 7 is used for according to the trigger signal. Acquire the actual image generated by the direct detection area array 1.

When the direct-type X-ray flat panel detector receives X-rays, the direct-type semiconductor 3 will directly generate a sub-hole signal according to the received X-rays to form a current, thereby directly reflecting the current flowing in the bias signal line 4 . Accurate exposure synchronization can be achieved by detecting the current in the bias signal line 4 and performing exposure according to the time of the current change as a trigger signal.

The specific structure of a direct X-ray flat panel detector provided by the present invention will be described in detail in the following invention embodiments.

Please refer to FIG. 3 , which is a schematic diagram of an enlarged structure of the pixel in FIG. 1 .

Different from the above-mentioned embodiments of the invention, the embodiments of the present invention are based on the above-mentioned embodiments of the invention, and further specifically define the structure of the pixels in the direct detection area array 1 and the structure of the current comparison module 6, and the rest of the content has been described above. A detailed introduction is made in the embodiments of the invention, and details are not repeated here.

Referring to FIG. 3 , in the embodiment of the present invention, the thickness of the direct semiconductor 3 ranges from 100 μm to 1000 μm, inclusive. That is, due to the manufacturing process at the current stage, the thickness of the direct semiconductor 3 disposed in a single pixel is usually between 100 μm and 1000 μm, inclusive of the end points. At this time, the capacitance of the direct type semiconductor 3 is relatively small, that is, it is difficult for the direct type semiconductor 3 to store a large amount of signal charges. Further, in the embodiment of the present invention, the pixel further includes a storage capacitor 8 , and the storage capacitor 8 is connected in parallel with the direct semiconductor 3 . The thickness of the above-mentioned storage capacitor 8 is usually about 1 μm. Therefore, by arranging the storage capacitor 8 in parallel with the direct semiconductor 3 , the signal charge storage capacity can be greatly increased.

In the embodiment of the present invention, the output end of the thin film transistor 2 is connected with a data line, and the data line is connected with a sense amplifier. When the thin film transistor 2 is turned on, the signal charges generated by the direct semiconductor 3 and the storage capacitor 8 can enter the data line through the output end of the thin film transistor 2 and be finally read. The above-mentioned readout amplifier is used to amplify the signal charge, so as to facilitate the detection of the signal charge. For the specific structure of the sense amplifier, reference may be made to the prior art, which will not be repeated here.

Under normal circumstances, one end of the direct semiconductor 3 and one end of the storage capacitor 8 in the same pixel will be connected to the same bias signal line 4, and the other end of the direct semiconductor 3 and the other end of the storage capacitor 8 will be connected to the thin film transistor 2 at the same time. the input terminal. When the thin film transistor 2 is turned on through the gate of the thin film transistor 2, that is, when its V _G is high, the signal charge can enter the sense amplifier through the data line to be amplified and converted into a digital image signal after digital-to-analog conversion. The specific process of reading the signal charges to generate the digital image signal will be described in detail in the following invention embodiments.

In the direct X-ray flat panel detector provided by the embodiment of the present invention, when the direct X-ray flat panel detector receives X-rays, the direct semiconductor 3 will directly generate sub-hole signals according to the received X-rays, forming current, so as to directly reflect the current flowing in the bias signal line 4 . Accurate exposure synchronization can be achieved by detecting the current in the bias signal line 4 and performing exposure according to the time of the current change as a trigger signal.

A method for synchronizing exposure of a direct X-ray flat panel detector provided by an embodiment of the present invention is described below. The exposure synchronization method described below and the direct X-ray flat panel detector described above can be referred to each other correspondingly.

Please refer to FIG. 4 and FIG. 5 . FIG. 4 is a flowchart of a method for synchronizing exposure of a direct X-ray flat panel detector according to an embodiment of the present invention; and FIG. 5 is an image acquisition sequence diagram.

In the embodiment of the present invention, the exposure synchronization method of the direct X-ray flat panel detector is specifically applied to the processor 7 provided in the direct X-ray flat panel detector, and the processor 7 is mainly used to control the direct X-ray flat panel detector to perform exposure. The specific connection relationship of the processor 7 has been described in detail in the above embodiments of the invention, and will not be repeated here.

Referring to Figure 4, the exposure synchronization method of the direct X-ray flat panel detector includes:

S101: Collect images generated by the direct detection area array at equal intervals.

In the embodiment of the present invention, the direct detection area array 1 includes a plurality of pixels distributed in an array, and the pixels include a thin film transistor 2 and a direct semiconductor 3 electrically connected to the thin film transistor 2; the direct semiconductor 3 is electrically connected with a bias voltage signal line 4, and the bias voltage signal line 4 is used for applying a predetermined magnitude of bias voltage to both ends of the direct semiconductor 3. The specific structure of the direct X-ray flat panel detector will be described in detail in the above-mentioned embodiments of the invention, and will not be repeated here.

Referring to FIG. 5 , in this step, the processor 7 acquires images generated by the direct detection area array 1 at equal intervals, where the acquisition time is usually referred to as ACQ time, and the interval time is usually referred to as IDLE time. The processor 7 will cyclically collect the images generated by the direct detection area array 1 according to this step, so as to determine the actual image in the following steps.

S102: Obtain the trigger signal sent by the current comparison module.

In an embodiment of the invention, the trigger signal is a signal generated by the current comparison module 6 when the current in the bias signal line 4 is greater than a current threshold. The specific content of the trigger signal has been introduced in detail in the above embodiments of the invention, and will not be repeated here. It should be noted that this step usually needs to be performed in parallel with the above S101, so as to perform accurate exposure.

S103: Determine the actual image from the image according to the trigger signal.

Specifically, this step generally includes: determining an original image and a background image from the image according to the trigger signal; and subtracting the background image from the original image to obtain the actual image. That is, in this step, it is usually necessary to first determine the original image and the background image from the images continuously acquired in the above S101 according to the time point of acquiring the trigger signal, and then subtract the value of each pixel of the original image from the value of each pixel of the background image. value to get the actual image.

The specific content of this step will be described in detail in the following invention embodiments, and will not be repeated here.

In a method for synchronizing exposure of a direct X-ray flat panel detector provided by an embodiment of the present invention, when the direct X-ray flat panel detector receives X-rays, the direct semiconductor 3 will directly generate sub-holes according to the received X-rays signal to form a current, which directly reflects the current flowing in the bias signal line 4 . Accurate exposure synchronization can be achieved by detecting the current in the bias signal line 4 and performing exposure according to the time of the current change as a trigger signal.

The specific content of the exposure synchronization method for a direct X-ray flat panel detector provided by the present invention will be described in detail in the following invention embodiments.

Please refer to FIG. 6 , FIG. 7 and FIG. 8 , FIG. 6 is a flowchart of a specific method for synchronizing exposure of a direct X-ray flat panel detector provided by an embodiment of the present invention; FIG. 7 is a timing diagram for obtaining trigger signals at intervals ; Fig. 8 is the timing chart of acquisition time acquisition trigger signal.

Referring to FIG. 6, in the embodiment of the present invention, the exposure synchronization method of the direct X-ray flat panel detector includes:

S201: Collect images generated by the direct detection area array at equal intervals.

S202: Obtain the trigger signal sent by the current comparison module.

The foregoing S201 to S202 are basically the same as those of S101 to S102 in the foregoing embodiment of the invention. For details, please refer to the foregoing embodiment of the invention, which will not be repeated here.

S203: When the time point of the trigger signal corresponds to the interval time, the image collected at the acquisition time before the time point of the trigger signal is used as the background image, and the image collected at the collection time after the time point of the trigger signal is used as the original image.

Referring to FIG. 7 , the time point at which the trigger signal is acquired is generally referred to as the Trigger. In this step, when the time point at which the trigger signal is acquired in S202 is at the interval time described in S201, that is, within the interval between two adjacent acquisitions of images, specifically, the time point at which the trigger signal is acquired at the previous acquisition time is collected. The image obtained is used as the background image, and the image collected at the next acquisition time after the trigger signal time is used as the original image, so that the actual image can be determined in the subsequent steps.

It should be noted that this step and the following S204 to S207 are usually executed in parallel.

S204: When the time point of the trigger signal corresponds to the collection time, the current remaining collection time is skipped.

Referring to FIG. 8 , when the time point at which the trigger signal is acquired in S202 is at the acquisition time described in S201, in general, in this step, it is necessary to quickly skip the remaining time of the current acquisition time to accumulate the exposure dose, and the remaining time is usually called SKIP. Generally, the skipping time required for skipping the current remaining acquisition time is less than 5% of the acquisition time, so as to ensure that the exposure dose can be quickly accumulated.

S205: Take the image collected at a collection time after the time point of the trigger signal as the original image.

In this step, the image collected at the next acquisition time after the trigger signal time is taken as the original image, and the original image is the original image formed by accumulating the exposure amount through an interval time.

S206: Use the image collected at the collection time corresponding to the time point of the trigger signal as the image of the corresponding area in the background image.

Since the time point at which the trigger signal is acquired in S202 is at the acquisition time described in S201, and a part of the image is acquired at the current acquisition time. Usually, the direct detection area array 1 will scan line by line to collect images. In this step, before acquiring the trigger signal, n lines of images are usually collected from the 1st line to the nth line, that is, part of the image. Correspondingly, in this step This part of the image collected by the center will be used as the image of the corresponding area in the background image, that is, as the image of the first row to the nth row in the background image. And the images of the remaining areas in the background image, that is, the images from the n+1th row to the last row, will be acquired in the following steps.

S207: Taking N times the interval time before the time point of the trigger signal, or N times the interval time after the acquisition time corresponding to the original image, the image corresponding to the remaining area in the background image in the collected image, as the image of the remaining area in the background image image.

In this embodiment of the present invention, the N is not less than 2. For the image of the remaining area in the above background image, that is, the image from the n+1th line to the last line, in this step, in the image collected at the acquisition time corresponding to N times the interval time before the trigger signal time point, Or N times the interval time after the acquisition time corresponding to the original image, that is, the images collected at the acquisition time corresponding to N+1 times the interval time after the trigger signal time point, the images from the n+1th line to the last line, that is, the corresponding The image of the remaining area in the background image, as the image of the remaining area in the background image, is combined with the partial images obtained in the above S206 to form a background image.

Specifically, in the embodiment of the present invention, the above N is usually equal to 2, even if a clear and complete background image is acquired as soon as possible. That is, this step usually includes: taking twice the interval time before the time point of the trigger signal, or twice the interval time after the acquisition time corresponding to the original image, the acquired image corresponds to the remaining area in the background image. , as the image of the remaining area in the background image.

S208: Subtract the background image from the original image to obtain an actual image.

This step has been described in detail in S103 in the above embodiment of the invention, and will not be repeated here.

In a method for synchronizing exposure of a direct X-ray flat panel detector provided by an embodiment of the present invention, when the direct X-ray flat panel detector receives X-rays, the direct semiconductor 3 will directly generate sub-holes according to the received X-rays signal to form a current, which directly reflects the current flowing in the bias signal line 4 . Accurate exposure synchronization can be achieved by detecting the current in the bias signal line 4 and performing exposure according to the time of the current change as a trigger signal.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments may be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant part can be referred to the description of the method.

Professionals may further realize that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two, in order to clearly illustrate the possibilities of hardware and software. Interchangeability, the above description has generally described the components and steps of each example in terms of functionality. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each particular application, but such implementations should not be considered beyond the scope of the present invention.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be directly implemented in hardware, a software module executed by a processor, or a combination of the two. A software module can be placed in random access memory (RAM), internal memory, read only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other in the technical field. in any other known form of storage medium.

Finally, it should also be noted that in this document, relational terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply these entities or there is any such actual relationship or sequence between operations. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

A direct X-ray flat panel detector and an exposure synchronization method for a direct X-ray flat panel detector provided by the present invention are described above in detail. The principles and implementations of the present invention are described herein by using specific examples, and the descriptions of the above embodiments are only used to help understand the method and the core idea of the present invention. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can also be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims (10)

1. A direct X-ray flat panel detector is characterized by comprising a direct detection area array, a current comparison module and a processor;

the direct detection area array comprises a plurality of pixels distributed in an array, wherein each pixel comprises a thin film transistor and a direct type semiconductor electrically connected with the thin film transistor; the direct type semiconductor is electrically connected with a bias signal wire, and the bias signal wire is used for applying bias with a preset magnitude to two ends of the direct type semiconductor;

the bias signal line is connected with the processor through the current comparison module, and the current comparison module is used for sending a trigger signal to the processor when the current in the bias signal line is greater than a current threshold;

the processor is used for acquiring an actual image generated by the direct detection area array according to the trigger signal.

2. The direct X-ray flat panel detector according to claim 1, wherein the materials of the direct semiconductor include:

amorphous selenium, monocrystalline silicon, high-purity germanium, tellurium-zinc-cadmium, cesium-lead-bromine and mA-lead-iodine.

3. Direct X-ray flat panel detector according to claim 2, characterized in that the direct semiconductor thickness ranges from 100 μ ι η to 1000 μ ι η, inclusive.

4. The direct X-ray flat panel detector according to claim 1, wherein the pixel further comprises a storage capacitor connected in parallel with the direct semiconductor.

5. The direct-type X-ray flat panel detector according to claim 4, wherein a data line is connected to an output end of the thin film transistor, and a sense amplifier is connected to the data line.

6. The direct X-ray flat panel detector according to claim 1, wherein all the bias signal lines are connected to the same bias signal bus; the bias signal bus is connected with the processor through the current comparison module.

7. The direct-type X-ray flat panel detector according to claim 6, wherein the current comparison module comprises an operational amplifier, and an output end of the operational amplifier is connected with the processor.

8. The direct X-ray flat panel detector according to claim 7, wherein the processor is an FPGA.

9. A method for synchronizing exposure of a direct X-ray flat panel detector is applied to a processor and comprises the following steps:

collecting images generated by a direct detection area array at equal intervals; the direct detection area array comprises a plurality of pixels distributed in an array, and each pixel comprises a thin film transistor and a direct semiconductor electrically connected with the thin film transistor; the direct type semiconductor is electrically connected with a bias signal wire, and the bias signal wire is used for applying bias with a preset magnitude to two ends of the direct type semiconductor;

acquiring a trigger signal sent by a current comparison module; the trigger signal is a signal generated by the current comparison module when the current in the bias signal line is greater than a current threshold;

determining an actual image from the image according to the trigger signal.

10. The method of claim 9, wherein determining an actual image from the images according to the trigger signal comprises:

determining an original image and a background image from the image according to the trigger signal;

and subtracting the background image from the original image to obtain the actual image.

Images