Radiographic imaging apparatus and method for driving radiographic imaging apparatus

Abstract

The present invention relates to a radiographic imaging apparatus and a method for driving the radiographic imaging apparatus and, more specifically, to a radiographic imaging apparatus and a method for driving the radiographic imaging apparatus, wherein the radiographic imaging apparatus can perform an automatic exposure control (AEC) function by analyzing pixel values of an image in real time during irradiation when treating a patient or the like using radiation.

Description

X-ray imaging device and method of operating the same

[0001] The present invention relates to a radiographic apparatus and a method for operating the radiographic apparatus, and more particularly, to a radiographic apparatus and a method for operating the radiographic apparatus capable of performing an automatic exposure control (AEC) function by analyzing pixel values ​​of an image in real time during radiation exposure.

[0002] Radiation generally plays a crucial role in protecting the human body from disease and advancing medicine, and radiography is an essential part of virtually all medical imaging procedures. Recent technological advancements, coupled with the shift to digital image acquisition methods for radiographic equipment, are rapidly changing the radiation exposure landscape.

[0003] While these digital medical environments offer the advantage of maximizing user convenience, reducing image noise and improving image quality can increase patient radiation exposure. Thus, medical radiation exposure accounts for the largest proportion of man-made radiation exposure. Recently, interest has been focused on medical radiation exposure management—methods for minimizing radiation exposure while maximizing diagnostic information.

[0004] Meanwhile, examinations using diagnostic radiation must be performed under appropriate conditions and with an appropriate dose. This requires understanding the subject's thickness and radiation absorption. However, because determining the subject's thickness and absorption and then irradiating the image based on these parameters is difficult in practice, control devices that utilize Automatic Exposure Control (AEC) to automatically deliver the appropriate radiation dose required for image acquisition are widely used.

[0005] Conventional automatic exposure control devices utilize ionization chambers, which are essentially radiation detectors. However, these ionization chamber-based technologies suffer from drawbacks such as reduced radiation detection accuracy or loss of some radiation signals, depending on the position of the ion chamber and detector.

[0006] In order to solve the above problems, the present invention aims to provide a radiographic apparatus capable of detecting an accurate radiation dose and implementing automatic exposure control (AEC) without having a separate device in the radiographic apparatus.

[0007] The present invention provides a radiographic apparatus comprising: an image detection unit including a plurality of pixel units arranged in a matrix form, and charging a charge proportional to the amount of radiation to the plurality of pixel units; a gate driver connected to at least one line of the image detection unit; a readout unit performing a readout operation for reading a value output from each pixel unit; and a control unit controlling the radiation exposure based on the pixel value of the pixel unit; wherein the control unit selects at least one line among the lines as a line for an automatic exposure control signal, calculates and stores an offset value of the selected line of the image detection unit for each pixel of the selected line in a state where no radiation is irradiated, calculates and stores a first image value of the selected line for each pixel of the selected line in a state where radiation is irradiated, and corrects the first image value by the offset value to calculate a second image value in a state where radiation is irradiated, and outputs an automatic exposure control signal for blocking the radiation irradiation.

[0008] In one embodiment, the offset value and the first image value can be each calculated by the difference between a value output from the pixel unit in the on state of the gate driver and a value output from the pixel unit in the off state of the gate driver while switching the gate driver of the selected line between an on state and an off state.

[0009] In one embodiment, the control unit may switch the gate driver of the selected line between an on state and an off state in a state where no radiation is irradiated, calculate the offset value by the difference between the value output from each pixel unit of the selected line in the gate on state and the value output from each pixel unit of the selected line in the gate off state, and calculate and store the offset value for each of the at least one pixel of the selected line.

[0010] In one embodiment, the control unit switches the gate driver of the selected line between an on state and an off state in a state where radiation is irradiated, calculates the first image value by the difference between a value output from each pixel unit of the selected line in a gate-on state and a value output from each pixel unit of the selected line in a gate-off state, and calculates and stores the first image value for each of the at least one pixel of the selected line.

[0011] Additionally, the control unit can compare the accumulated value of the second image value in the at least one pixel with a reference value and output the automatic exposure control signal.

[0012] Additionally, the control unit can output the automatic exposure control signal using the accumulated average of the second image values ​​in the plurality of pixels arranged in the selected line.

[0013] In one embodiment, when one line is selected as the line for the automatic exposure control signal, the control unit may calculate an average second image value of a plurality of pixels of the selected line in each readout cycle, accumulate and store the average second image value as the readout cycle is repeated, and compare the accumulated second image value with a reference value to output the automatic exposure control signal.

[0014] In one embodiment, when two or more lines are selected as lines for the automatic exposure control signal, the control unit may calculate an average second image value of a plurality of pixels for each selected line in each readout cycle, and as the readout cycle is repeated, accumulate and add the average second image value for each selected line to calculate an overall average value, and compare the overall average value with a reference value to output the automatic exposure control signal.

[0015] In addition, the present invention provides a method for driving a radiographic imaging apparatus, comprising: a step of selecting at least one line in an image detection unit; a step of calculating and storing an offset value of the selected line for each pixel of the selected line in a state where no radiation is irradiated; a step of calculating and storing a first image value of the selected line for each pixel of the selected line in a state where radiation is irradiated; a step of calculating a second image value in a state where radiation is irradiated by correcting the first image value by the offset value and storing the second image value for each pixel of the selected line; and a step of outputting an automatic exposure control signal for blocking the radiation irradiation by the second image value of the selected line.

[0016] In one embodiment, the offset value and the first image value are each calculated by the difference between a value output from the pixel unit in the on state of the gate driver and a value output from the pixel unit in the off state of the gate driver while switching the gate driver of the selected line between the on state and the off state.

[0017] In one embodiment, the step of calculating and storing the offset value for each pixel of the selected line may be performed by switching the selected line between a gate-on state and a gate-off state in a state where no radiation is irradiated, calculating the offset value by a difference between a value output from each pixel unit of the selected line in the gate-on state and a value output from each pixel unit of the selected line in the gate-off state, and calculating and storing the offset value for each pixel of the at least one pixel of the selected line.

[0018] In one embodiment, the step of calculating and storing the first image value for each pixel of the selected line may be performed by switching the selected line between a gate-on state and a gate-off state in a state where radiation is irradiated, calculating the first image value by a difference between a value output from each pixel unit of the selected line in the gate-on state and a value output from each pixel unit of the selected line in the gate-off state, and calculating and storing the first image value for each pixel of the at least one selected line.

[0019] Additionally, the automatic exposure control signal may be output by comparing the accumulated value of the second image value in at least one pixel with a reference value.

[0020] Additionally, the automatic exposure control signal can be output using the accumulated average of the second image values ​​in a plurality of pixels arranged in the selected line.

[0021] In one embodiment, when the one line is selected as the line for the automatic exposure control signal, the step of outputting the automatic exposure control signal may be performed by calculating an average second image value of a plurality of pixels of the selected line in each readout cycle, accumulating and storing the average second image value as the readout cycle is repeated, and comparing the accumulated second image value with a reference value to output the automatic exposure control signal.

[0022] In one embodiment, when two or more lines are selected as lines for the automatic exposure control signal, the step of outputting the AEC signal may be performed by calculating an average second image value of a plurality of pixels for each selected line in each readout cycle, accumulating the average second image value for each selected line as the readout cycle is repeated, calculating an overall average value, and comparing the overall average value with a reference value to output the automatic exposure control signal.

[0023] According to the present invention, automatic exposure control (AEC) can be implemented by detecting an accurate radiation dose without having a separate device in a radiographic apparatus.

[0024] That is, according to the present invention, by correcting the first image value calculated in a state where radiation is irradiated by the offset value calculated in a state where radiation is not irradiated to calculate the second image value, the radiation dose due to radiation irradiation can be measured in real time and accurate automatic exposure control (AEC) can be implemented.

[0025] FIG. 1 is a schematic diagram showing the configuration of a radiographic system equipped with a radiographic device according to one embodiment of the present invention.

[0026] FIG. 2 is a block diagram illustrating the configuration of a radiographic apparatus according to one embodiment of the present invention.

[0027] FIG. 3 is a schematic diagram illustrating an image sensor unit and a control unit of a radiographic apparatus according to one embodiment of the present invention.

[0028] Figure 4 is a flowchart illustrating a method of driving a radiographic apparatus according to one embodiment of the present invention.

[0029] FIG. 5 is a drawing for explaining a process of calculating an offset value in a radiographic apparatus according to one embodiment of the present invention.

[0030] FIG. 6 is a drawing for explaining a process of calculating a first image value in a radiographic apparatus according to one embodiment of the present invention.

[0031] FIG. 7 is a drawing for explaining a process of calculating a second image value in a radiographic apparatus according to one embodiment of the present invention.

[0032] The present invention is capable of various modifications and embodiments. Specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it is to be understood that all modifications, equivalents, and alternatives included within the technical spirit and scope of the present invention are included. In describing the present invention, if a detailed description of a related known technology is judged to obscure the gist of the present invention, the detailed description will be omitted.

[0033] Terms like "first" and "second" may be used to describe various components, but these terms do not limit the components themselves. These terms are used solely to distinguish one component from another.

[0034] The terminology used in this invention is solely for the purpose of describing specific embodiments and is not intended to limit the invention. The terminology used in this invention has been selected from widely used, current terms, taking into account the functions of the invention. However, this may vary depending on the intentions of those skilled in the art, precedents, or the emergence of new technologies. Furthermore, in certain cases, the applicant may arbitrarily select terms, in which case their meanings will be described in detail in the relevant description of the invention. Therefore, the terms used in this invention should not be defined simply as names of terms, but rather based on their meanings and the overall content of the invention.

[0035] Singular expressions include plural expressions unless the context clearly dictates otherwise. In the present invention, terms such as "comprise" or "have" are intended to indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but should be understood not to preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0036] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. In the description with reference to the attached drawings, identical or corresponding components are assigned the same drawing numbers, and redundant descriptions thereof will be omitted. Fig. 1 is a schematic diagram illustrating the configuration of a radiographic system equipped with a radiographic apparatus according to one embodiment of the present invention.

[0037] Referring to FIG. 1, a radiographic system (1000) may include a radiographic device (300) that irradiates radiation and a radiographic device (100) that creates an image of an object by radiation that has passed through the object (H).

[0038] The radiation irradiated by the radiation irradiation device (300) is typically X-ray, but is not limited thereto and may be replaced with various other radiations. The following description assumes X-rays.

[0039] FIG. 2 is a block diagram illustrating a configuration of a radiographic apparatus according to one embodiment of the present invention. The radiographic apparatus (100) according to one embodiment of the present invention is described as an indirect conversion method having a scintillator panel (112). However, the present invention is not limited thereto, and can also be applied to a direct conversion method in which, for example, photoconductive charges generated inside a photoconductive film by X-rays are directly conducted to a storage capacitor for charge accumulation by a high electric field.

[0040] Referring to FIG. 2, the radiographic apparatus (100) may be equipped with an image sensor unit (110) that can charge a charge proportional to the amount of radiation irradiated from the radiation irradiation apparatus (300) and read the charged value, and a control unit (130) that controls the image sensor unit (110).

[0041] Specifically, the image sensor unit (110) may be equipped with a plurality of pixel units (120) arranged in a matrix form, an image detection unit (116) that charges the plurality of pixel units (120) with a charge proportional to the amount of radiation, a gate driver (114) that selects at least one line (122) from the image detection unit (116), and a readout unit (118) that reads the value output from each pixel unit (120) of the selected line (122). Furthermore, the image sensor unit (110) may further be equipped with a scintillator panel (112) that converts X-rays into fluorescence (or visible light).

[0042] FIG. 3 is a schematic diagram illustrating an image sensor unit and a control unit of a radiographic apparatus according to one embodiment of the present invention. In FIG. 3, the scintillator panel (112) is omitted for convenience of illustration.

[0043] Referring to FIGS. 2 and 3, the image detection unit (116) may include a plurality of pixel units (120) arranged in a matrix form.

[0044] The above plurality of pixel units (120) may include, although not shown in the drawing, a photoelectric conversion element, for example, a photodiode that converts visible light into charge, a capacitor to which charge converted from the photoelectric conversion element is supplied and accumulated, and a TFT (Thin-film transistor) that performs switching of charge accumulation and discharge to the capacitor.

[0045] Meanwhile, the plurality of pixel units (120) described above can be connected to the gate driver (114) through a plurality of lines (122).

[0046] In this case, the control unit (130) can select at least one line (122) from among the plurality of lines included in the image detection unit (116). In one embodiment, the selection of the at least one line (122) can be performed by the control of the gate driver (114). In the implementation of the present invention, the selection of the one or more lines (122) by the gate driver (114) can be performed before or after the start of radiation irradiation.

[0047] For example, the gate driving unit (114) has a gate driver (not shown) connected to at least one line (122), and the ON state and OFF state of the gate driver can be switched for a specific line (122).

[0048] The readout unit (118) reads the charge value charged in each pixel unit (120) of at least one line (122) selected by the gate driver (114), and the charge value read by the readout unit (118) can be transmitted to the control unit (130) as a pixel value of each pixel unit (120).

[0049] When performing a flush operation of the radiographic apparatus (100), the readout unit (118) can remove dark current accumulated in each pixel unit of the image detection unit (116) by discarding the charge value of each pixel unit (120) without reading it. On the other hand, when performing a readout operation of the radiographic apparatus (100), the readout unit (118) can read the charge value of each pixel unit (120) to obtain analog data in the form of voltage, convert it into digital data, and transmit it to the control unit (130).

[0050] The control unit (130) can accumulate and store digital data received from the lead-out unit (118) by combining them in line units, and transmit them to the image processing unit (140) through a data communication unit (not shown).

[0051] Meanwhile, in order to achieve the AEC function, it is necessary to detect the dose of radiation (e.g., X-ray) while radiation is being irradiated to the image sensor unit (110). To this end, in the radiographic apparatus (100) according to the present invention, at least one line (122) among the plurality of lines (122) of the image detection unit (116) can be utilized as a sensor for detecting radiation.

[0052] Hereinafter, a driving method for outputting an AEC signal using a radiographic device (100) having the aforementioned configuration will be examined.

[0053] Figure 4 is a flowchart illustrating a method for operating a radiographic apparatus according to one embodiment of the present invention. The method for operating a radiographic apparatus described below may be performed by the control unit (130) of the radiographic apparatus (100). For example, the method may be stored in the control unit (130) in the form of a program and executed, but is not limited thereto.

[0054] Referring to FIG. 4, the driving method may include a step of selecting at least one line (122) from an image detection unit (116) (S410), a step of calculating and storing an offset value of the selected line (122) for each pixel of the selected line (122) in a state where no radiation is irradiated (S430), a step of calculating and storing a first image value of the selected line (122) for each pixel of the selected line (122) in a state where radiation is irradiated (S450), a step of calculating a second image value in real time by correcting the first image value by the offset value in a state where radiation is irradiated and storing the second image value for each pixel of the selected line (122) in a state where radiation is irradiated (S470), and a step of outputting an AEC signal for blocking the radiation irradiation by the second image value (S490).

[0055] When reading the charge value in the pixel unit (120) of the image detection unit (116) by irradiating radiation, the charge value of the pixel unit (120) may be obtained as a different value from the charge value generated by the actual radiation irradiation. This is presumed to be due to the characteristics of electronic components including TFTs. In the present invention, in order to obtain the charge value generated by the actual radiation irradiation when obtaining the AEC signal from the pixel units (120) of the selected line (122), the offset value obtained in step S430 is used. In addition, when the read-out unit (118) obtains the charge value of the pixel units (120) in a state where no radiation is irradiated or a state where radiation is irradiated, the charge value obtained by the read-out unit (118) may vary over time as the state of the electronic components including TFTs changes. In the present invention, in steps S430 and S450, a more accurate and precise AEC signal can be obtained by acquiring the charge values ​​of each pixel unit (120) while repeatedly controlling the On / Off of the gate driver for the selected line (122).

[0056] In step S410, the control unit (130) can select at least one line (122) from the image detection unit (116) as a radiation sensor for generating an AEC signal through the gate driving unit (114). Here, the selected line (122) is not particularly limited, and at least one line (122) in a specific row can be designated in advance or randomly designated. In addition, the control unit (130) can select only one line (122), or can select two or more lines (122) as radiation sensors for generating an AEC signal.

[0057] In step S430, the control unit (130) calculates and stores the offset value of the selected line (122) for each pixel of the selected line (122). In step S430, the offset value of the selected line (122) can be calculated in a state where no radiation is irradiated to the image sensor unit (110).

[0058] FIG. 5 is a drawing for explaining a process of calculating an offset value in a radiographic apparatus according to one embodiment of the present invention.

[0059] (A) of Fig. 5 shows whether radiation is irradiated (X-ray), (B) of Fig. 5 shows the number of turns (n) of readout and the TFT control signal (gate on / off signal) according to it, and (C) of Fig. 5 shows the offset value (OV) for one pixel unit (120) belonging to the selected line (122). n ) is indicated.

[0060] Referring to (A) of Fig. 5, radiation is not irradiated during the process of calculating the offset value.

[0061] In the present invention, for the selected line (122) to obtain an AEC signal for automatic exposure control, a readout operation is performed by a readout unit (118) while the gate driving unit (114) is turned on / off repeatedly at a predetermined cycle.

[0062] Referring to (B) of FIG. 5, gate on / off is repeated at a predetermined cycle for the selected line (122). In the first (n=1) read-out operation, the read-out unit (118) can acquire the pixel value of each pixel unit according to the charge value of the pixel units (120) included in the selected line (122) when the TFT control signal is on, and can acquire the pixel value of each pixel unit according to the charge value of the pixel units (120) included in the selected line (122) when the TFT control signal is off.

[0063] That is, the aforementioned readout cycle may include at least one readout operation. For example, in the first readout cycle (n=1), the readout operation may be performed once when the TFT control signal is on, and then performed once again when the TFT control signal is off. Consequently, when the readout is performed up to N cycles, the readout operation for the selected line (122) may be performed substantially '2N' times.

[0064] Referring to (C) of Fig. 5, the offset value (OV) of one of the pixels arranged on the line (122) selected for the readout 'n' times n , n is an integer greater than or equal to 1) is shown as an example. For intuitive understanding, (C) of Fig. 5 shows the offset value (OV) according to the readout cycle. n ) is adding a line connecting them.

[0065] Referring to FIG. 5, the control unit (130) can repeatedly switch the gate driver of the selected line (122) between the ON state and the OFF state through a TFT control signal in a state where no radiation is irradiated. The read-out unit (118) reads the values ​​output from each pixel unit (120) of the selected line (122) in the gate-on state and the values ​​output from each pixel unit of the selected line (122) in the gate-off state through the read-out operation, and the control unit (130) calculates the offset value (OV) of each pixel based on the difference. n ) can be calculated.

[0066] Here, the offset value can be defined as a charge value accumulated in the pixel unit (120) in a state where no radiation is irradiated. In order to measure the offset value more accurately, in the present invention, the gate driver of the selected line (122) is switched on and off in a state where no radiation is irradiated, the pixel value is read, and the difference is calculated as the offset value. Consequently, the offset value can be calculated using the following [Mathematical Formula 1].

[0067]

[0068] In [Mathematical Formula 1], 'x' corresponds to an index value indicating the position of a pixel arranged on the selected line (122). For example, if 'a' pixels are arranged on the selected line (122), 'x' can be determined as an integer value from 1 to a predetermined 'a' (x is an integer, 1≤x≤a). In addition, 'n' means the number of turns of the aforementioned readout and corresponds to an integer greater than or equal to 1 (n is an integer greater than or equal to 1).

[0069] Therefore, in the case of the first readout (n=1), the offset value can be calculated and stored for each pixel arranged in the selected line (122). This readout can be repeated up to N times (n=N), and the offset value can be calculated and stored for each pixel for each readout.

[0070] In one embodiment, the control unit (130) may preset the total number of readout cycles N, or repeat the aforementioned readout cycle N or more times until the offset value converges. The offset values ​​calculated by repeating the readout cycle in this manner may be stored for each pixel.

[0071] In one embodiment, the initial point in time (T1) for calculating the offset value of the selected line (122) may be appropriately determined. For example, the point in time (T0) immediately after performing the flush operation may be set as the reference point, and the point in time (T1) may be set as a predetermined time elapsed from the reference point.

[0072] The step of calculating and storing the aforementioned offset value can be performed in the same manner for a plurality of selected lines (122) even when there are two or more lines (122) selected by the gate driver (114). In step S430, the control unit (130) calculates and stores the offset value, and in step S450, the control unit (130) can calculate and store the first image value of the selected line (122) for each pixel of the selected line (122). Step S450 can be performed in a state where radiation is irradiated.

[0073] FIG. 6 is a drawing for explaining a process of calculating a first image value in a radiographic apparatus according to one embodiment of the present invention.

[0074] (A) of Fig. 6 shows whether radiation is irradiated (X-ray), (B) of Fig. 6 shows the number of turns (n) of readout and the TFT control signal (gate on / off signal) according to it, and (C) of Fig. 6 shows the first image value (FIV) for one pixel unit (120) belonging to the selected line (122) n ) is indicated.

[0075] Referring to (B) of FIG. 6, the control unit (130) can switch the gate driver of the selected line (122) between an ON state and an OFF state while radiation is being irradiated. In this case, the values ​​output from each pixel unit (120) of the selected line (122) in the gate ON state and the values ​​output from each pixel unit (120) of the selected line (122) in the gate OFF state are read through the readout unit (118), and the first image value of each pixel can be calculated based on the difference therebetween.

[0076] When calculating the above first image value, if the pixel value is measured by simply turning on the gate driver of the selected line (122) in a state where radiation is irradiated, a pixel value that is larger than the actual amount of radiation irradiated can be obtained due to a change in the TFT applied voltage, a change in the gate driver applied voltage, or leakage from the photodiode.

[0077] In this regard, in the present invention, in order to more accurately measure the first image value, the gate driver of the selected line (122) is switched on and off while radiation is being irradiated, each pixel value is read, and the difference between them is calculated as the first image value. Consequently, the first image value can be calculated using the following [Mathematical Formula 2].

[0078]

[0079] The explanation for 'x' and 'n' in the above [Mathematical Formula 2] is the same as the above [Mathematical Formula 1]. The first image value (FIV(x) n ) can be repeatedly calculated in a state where radiation is irradiated, and the first image value (FIV(x) n ) can be stored in real time for each pixel.

[0080] In addition, the step (S450) of calculating and storing the first image value described above can be performed in the same manner for a plurality of selected lines (122) even when there are two or more lines (122) selected by the gate driving unit (114), i.e., a plurality of lines.

[0081] Referring to (C) of Fig. 6, the first image value (FIV) of one of the pixels arranged on the line (122) selected in the readout 'n' times n ) is shown as an example. For intuitive understanding, in (C) of Fig. 6, the first image value (FIV) according to the readout cycle n ) is adding a line connecting them.

[0082] At step S470, the control unit (130) can calculate and store the second image value of each pixel in a state where radiation is irradiated by correcting the first image value by the offset value.

[0083] FIG. 7 is a diagram for explaining a process of calculating a second image value in a radiographic apparatus according to one embodiment of the present invention. FIG. 7 (A) illustrates an offset value according to FIG. 5 (C), FIG. 7 (B) illustrates a first image value according to FIG. 6 (C), and FIG. 7 (C) illustrates a second image value calculated using the offset value and the first image value.

[0084] Referring to FIG. 7, the control unit (130) can correct the first image value by the offset value and calculate the second image value as in (C) of FIG. 7 and store it for each pixel.

[0085] For example, the control unit (130) may control the first image value (FIV(x)) of each pixel. n ) in the above offset value (OV(x) n ) is the value obtained by subtracting the second image value (SIV(x) n ) can be calculated. That is, the second image value can be calculated by [Mathematical Formula 3] below.

[0086]

[0087] In the above [Mathematical Formula 3], the explanations for 'x' and 'n' are the same as in the above [Mathematical Formula 1] and [Mathematical Formula 2]. That is, the second image value can be calculated and stored for each pixel arranged on the selected line (122) in the first readout (n=1) for each pixel. This readout can be repeated up to N times (n=N), and the second image value can be calculated and stored for each pixel in each readout. (C) of Fig. 7 shows the second image value (SIV) of one pixel among the pixels arranged on the selected line (122). n ) is shown as an example. Referring to (A) to (C) of Fig. 7, the first image value (FIV n ) in the offset value (OV n ) by subtracting the second image value (SIV) according to the actual radiation exposure n ) can be acquired, and the second image value of each pixel due to radiation can be accurately calculated in real time in the section where radiation is irradiated (the 'Exposure' section in (C) of Fig. 7).

[0088] In the practice of the present invention, the AEC signal may be generated by accumulating the second image value of at least one of the pixel units (120) belonging to the selected line (122), or by accumulating and then averaging the second image values ​​of the pixel units (120) belonging to the selected line (122). For example, as the readout cycle progresses, the second image value of at least one of the pixel units (120) belonging to the selected line (122) may be accumulated, and when the accumulated value reaches or exceeds a reference value, the AEC signal may be generated. Alternatively, in order to obtain a more general result, the AEC signal may be generated by calculating an average value of the second image values ​​of a plurality of pixel units (120) belonging to the selected line (122) for each readout cycle and accumulating the calculated average value.

[0089] In one embodiment, the average second image value (SIV) of the selected line (122) in the nth readout average(n) ) can be calculated by [Mathematical Formula 4] below.

[0090]

[0091] The explanations for 'x' and 'n' in the above [Mathematical Formula 4] are the same as in the above [Mathematical Formula 1] to [Mathematical Formula 3].

[0092] Referring to mathematical expression 4, the average second image value (SIV average(n) ) corresponds to the sum of the second image values ​​(SIV(x)n) of each pixel of the selected line (122) in the readout 'n' times divided by the number of pixels (a). That is, the average second image value (SIV average(n) ) corresponds to the average second image value of all pixels arranged in the selected line (122) in the nth readout.

[0093] At step S470, the control unit (130) can output an AEC signal for blocking the radiation exposure based on a real-time accumulated value of the average second image value of the selected line (122).

[0094] Specifically, when there is one selected line (122) as described above, the control unit (130) can accumulate and add up the average second image value of the selected line (122), compare the accumulated and added average second image value with a preset reference value, and output the AEC signal.

[0095] For example, the control unit (130) can output the AEC signal when the accumulated average second image value is greater than or equal to a preset reference value.

[0096] Meanwhile, in the case where there are two or more selected lines (122), i.e., multiple lines, the control unit (130) may first calculate an average second image value for each selected line (122), and then calculate an overall average value of the accumulated sum of the average second image values ​​thus calculated. This overall average value may be compared with a preset reference value to output the AEC signal.

[0097] For example, the control unit (130) can output the AEC signal when the overall average value is greater than or equal to a preset reference value.

[0098] A device according to embodiments of the present invention may include a processor, a memory for storing and executing program data, permanent storage such as a disk drive, a communication port for communicating with an external device, a user interface device such as a touch panel, a key, a button, etc. Methods implemented as software modules or algorithms may be stored on a computer-readable recording medium as computer-readable codes or program instructions executable on the processor. Here, the computer-readable recording medium includes a magnetic storage medium (e.g., read-only memory (ROM), random-access memory (RAM), floppy disk, hard disk, etc.) and an optical reading medium (e.g., CD-ROM, DVD: Digital Versatile Disc)). The computer-readable recording medium may be distributed to computer systems connected through a network, so that the computer-readable code may be stored and executed in a distributed manner. The medium may be readable by a computer, stored in a memory, and executed by a processor.

[0099] The specific implementations described in the embodiments are merely exemplary and do not limit the scope of the embodiments in any way. For the sake of brevity of the specification, descriptions of conventional electronic components, control systems, software, and other functional aspects of the systems may be omitted. In addition, the lines connecting or connecting members between components illustrated in the drawings are merely exemplary functional connections and / or physical or circuit connections, and may be replaced or represented as various additional functional connections, physical connections, or circuit connections in an actual device. In addition, unless specifically mentioned as "essential," "important," etc., a component may not be absolutely necessary for the application of the present invention.

[0100] The above description is merely an illustrative description of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications, changes, and substitutions may be made without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical idea of ​​the present invention, but rather to explain it, and the scope of the technical idea of ​​the present invention is not limited by these embodiments and the accompanying drawings. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

[0101] [Explanation of symbols]

[0102] 100: X-ray imaging device

[0103] 110: Image sensor section

[0104] 112: Scintillator

[0105] 114: Gate drive unit

[0106] 116: Image detection unit

[0107] 118: Leadout section

[0108] 120: pixel unit

[0109] 122: Line

[0110] 130: Control unit

[0111] 140: Image processing unit

[0112] 300: Radiation irradiation device

Claims

1. An image detection unit including a plurality of pixel units arranged in a matrix form, and charging a charge proportional to the amount of radiation to the plurality of pixel units; A gate driver connected to at least one line of the image detection unit; A readout unit that performs a readout operation to read the value output from the pixel unit; and A control unit for controlling the radiation exposure based on the pixel value of the pixel unit; The above control unit, Select at least one of the above lines as a line for an automatic exposure control signal, In a state where no radiation is irradiated, the offset value of the selected line of the image detection unit is calculated and stored for at least one pixel of the selected line, In a state where radiation is irradiated, the first image value of the selected line is calculated and stored for each pixel of the selected line, A radiographic apparatus characterized in that it calculates a second image value in a state where radiation is irradiated by correcting the first image value by the offset value and outputs an automatic exposure control signal that blocks the radiation irradiation.

2. In paragraph 1, A radiographic apparatus characterized in that the offset value and the first image value are each calculated by the difference between the value output from the pixel unit in the on state of the gate driver and the value output from the pixel unit in the off state of the gate driver while switching the gate driver of the selected line between the on state and the off state.

3. In paragraph 1, The above control unit A radiographic apparatus characterized in that the offset value is calculated by the difference between the value output from each pixel unit of the selected line in the gate-on state and the value output from each pixel unit of the selected line in the gate-off state by switching the gate driver of the selected line between an on state and an off state in a state where no radiation is irradiated, and the offset value is calculated and stored for each pixel of the at least one pixel of the selected line.

4. In any one of paragraphs 1 to 3, The above control unit A radiographic apparatus characterized in that, in a state where radiation is irradiated, the gate driver of the selected line is switched on and off, the first image value is calculated by the difference between the value output from each pixel unit of the selected line in the gate-on state and the value output from each pixel unit of the selected line in the gate-off state, and the first image value is calculated and stored for each pixel of the at least one selected line.

5. In paragraph 4, A radiographic apparatus characterized in that the control unit compares the accumulated value of the second image value in at least one pixel with a reference value and outputs the automatic exposure control signal.

6. In paragraph 4, A radiographic apparatus characterized in that the control unit outputs the automatic exposure control signal using the accumulated average of the second image values ​​in a plurality of pixels arranged in the selected line.

7. In paragraph 1, When one line is selected as the line for the above automatic exposure control signal, The above control unit, In each readout cycle, the average second image value of multiple pixels of the selected line is calculated, By repeating the above readout cycle, the average second image value is accumulated and stored, A radiographic apparatus characterized in that it outputs the automatic exposure control signal by comparing the accumulated second image value with a reference value.

8. In paragraph 1, When two or more lines are selected as the lines for the above automatic exposure control signal, The above control unit, In each readout cycle, the average second image value of multiple pixels is calculated for each selected line, By repeating the above readout cycle, the average second image value is accumulated and added for each selected line to calculate the overall average value, A radiographic apparatus characterized in that it outputs the automatic exposure control signal by comparing the overall average value with a reference value.

9. A step of selecting at least one line in the image detection unit; A step of calculating and storing the offset value of the selected line for each pixel of the selected line in a state where no radiation is irradiated; A step of calculating and storing the first image value of the selected line for each pixel of the selected line while being irradiated with radiation; A step of calculating a second image value in a state where radiation is irradiated by correcting the first image value by the offset value and storing the second image value for each pixel of the selected line; and A method for driving a radiographic apparatus, characterized in that it comprises a step of outputting an automatic exposure control signal for blocking the radiation irradiation by the second image value of the selected line.

10. In paragraph 9, A method for driving a radiographic apparatus, characterized in that the offset value and the first image value are each calculated by the difference between the value output from the pixel unit in the on state of the gate driver and the value output from the pixel unit in the off state of the gate driver while switching the gate driver of the selected line between the on state and the off state.

11. In paragraph 9, The step of calculating and storing the above offset value for each pixel of the selected line is A method for driving a radiographic apparatus, characterized in that the offset value is calculated by the difference between the value output from each pixel unit of the selected line in the gate-on state and the value output from each pixel unit of the selected line in the gate-off state by switching the selected line between a gate-on state and a gate-off state in a state where no radiation is irradiated, and the offset value is calculated and stored for each pixel of the at least one selected line.

12. In any one of paragraphs 9 to 11, The step of calculating and storing the above first image value for each pixel of the selected line is A method for driving a radiographic imaging device, characterized in that the first image value is calculated by the difference between the value output from each pixel unit of the selected line in the gate-on state and the value output from each pixel unit of the selected line in the gate-off state by switching the selected line between a gate-on state and a gate-off state in a state where radiation is irradiated, and the first image value is calculated and stored for each pixel of the at least one selected line.

13. In paragraph 12, A driving method of a radiographic apparatus, characterized in that the automatic exposure control signal is output by comparing the accumulated value of the second image value in at least one pixel with a reference value.

14. In paragraph 12, A driving method of a radiographic apparatus, characterized in that the automatic exposure control signal is output using the accumulated average of the second image values ​​in a plurality of pixels arranged in the selected line.

15. In paragraph 9, The step of outputting the automatic exposure control signal when the one line is selected as the line for the automatic exposure control signal is, In each readout cycle, the average second image value of multiple pixels of the selected line is calculated, By repeating the above readout cycle, the average second image value is accumulated and stored, A driving method of a radiographic apparatus characterized in that the automatic exposure control signal is output by comparing the accumulated second image value with a reference value.

16. In paragraph 9, The step of outputting the AEC signal when two or more lines are selected as lines for the automatic exposure control signal is as follows: In each readout cycle, the average second image value of multiple pixels is calculated for each selected line, By repeating the above readout cycle, the average second image value is accumulated and added for each selected line to calculate the overall average value, A driving method of a radiographic apparatus characterized in that the automatic exposure control signal is output by comparing the overall average value with a reference value.

Images