JP2017213292A - Radiographic apparatus, radiographic system, radiographic method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible that even when an excessive signal which exceeds a dynamic range of a detector is input, the input signal can appropriately be estimated.SOLUTION: A radiographic apparatus according to the present invention comprises: detecting means including a first pixel which detects radiation and reads a radiation signal at a predetermined frame rate and a second pixel which detects the radiation and reads a radiation signal at a frame rate higher than that for the first pixel; and estimating means which uses the radiation signal read by the second pixel to estimate the radiation signal in excess of the amount of saturating signal of the first pixel.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radiation imaging apparatus, a radiation imaging system, a radiation imaging method, and a program.

  In recent years, radiation imaging apparatuses using an FPD (Flat Panel Detector) have been widely used. This is a digital radiographic apparatus using a detection apparatus in which a large number of semiconductor elements for converting radiation into electrical signals are arranged in a two-dimensional matrix.

  A radiation imaging apparatus using an FPD charges information of radiation that has passed through a subject as a charge to a semiconductor element, then performs a read operation to transfer the charge information, and performs A / D conversion to create digital image information. .

  However, it is difficult to read out all the charges charged in one transfer operation, and a part of the charges may remain in the semiconductor element even after reading. When the next imaging is performed in this state, a phenomenon in which the residual charge is superimposed on the next radiation image as an afterimage occurs, and image quality may be deteriorated in subsequent imaging. Therefore, in the radiographic apparatus, how to reduce the influence of the afterimage of the previous shooting at the time of shooting is a problem.

  Such afterimages are generally known to be affected by the shooting conditions of the previous shooting, in particular, the amount of input signal, the time since the previous shooting, and the operating temperature of the detection device. Afterimage correction processing using this feature Has been tried so far.

  For example, Patent Document 1 reports a technique for estimating the amount of afterimage based on information on shooting conditions at the time of previous shooting and performing correction processing. Patent Document 2 reports a technique for acquiring afterimage data and using it for correction by acquiring an image in a non-irradiated state between the previous shooting and the next shooting.

JP 2006-135748 A JP 2009-201587 A

  The prior art has the following problems. As in Patent Document 1, in order to use the shooting conditions of the previous shooting, it is important to accurately grasp the amount of the input signal. However, if an extremely strong signal is input in the previous shooting, the amount of charge stored in the pixel exceeds the dynamic range of the detection device (mostly an A / D converter) and saturation occurs, so that A situation occurs in which the original input signal cannot be obtained correctly from the generated image.

  Even in a region that exceeds the dynamic range of the detection device, an afterimage is generated as the input is stronger. Under such circumstances, the afterimage amount is underestimated, and there is a possibility that an afterimage correction residue may occur.

  In Patent Document 2, although the problem of Patent Document 1 due to saturation can be solved, time cost for newly acquiring afterimage data must be paid between the previous shooting and the shooting. In use cases where the shooting interval must be shortened, such as when performing an emergency shooting procedure, there is a risk that afterimage data cannot be acquired and the afterimage cannot be corrected appropriately.

  The present invention has been made in view of the above problems, and provides a radiation imaging apparatus capable of accurately obtaining an input signal even when an excessive signal exceeding the dynamic range of the detection apparatus is input. Objective.

  The radiographic imaging device of the present invention includes a first pixel that detects radiation and reads out a radiation signal at a predetermined frame rate, and a first pixel that detects the radiation and reads out the radiation signal at a frame rate higher than that of the first pixel. Detection means including two pixels, and estimation means for estimating the amount of the radiation signal that exceeds the saturation signal amount of the first pixel using the radiation signal read by the second pixel. .

  According to the configuration of the present invention, even when an excessive signal that exceeds the dynamic range of the detection apparatus is input, the input signal can be appropriately estimated.

It is a block diagram which shows the example of a structure of the radiography apparatus which concerns on embodiment. It is a structural example of a detection apparatus. It is a flowchart which shows the example of the process which the radiography apparatus which concerns on embodiment performs. It is a figure which shows the example of the time change of the afterimage amount after the 1st image imaging | photography in a detection apparatus. It is a flowchart which shows the example of an input signal analysis process. It is the schematic of the output signal of the 1st pixel when X-rays are uniformly input to the detection device. It is the schematic of the output signal of the 2nd pixel when X-rays are uniformly input to the detection device. It is the schematic of the sum and loss of the output signal of a 2nd pixel in case X-rays are uniformly input into the detection apparatus. It is the figure which showed an example of the pixel arrangement | positioning of a detection apparatus. It is a flowchart which shows the example of the process which produces an estimated input signal image.

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

  First, the configuration of a radiation imaging apparatus and a radiation imaging system according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram illustrating an example of a basic configuration of a radiation imaging apparatus.

  The radiation imaging apparatus 100 includes a radiation generation apparatus 101 that generates radiation, a bed 103 that lays the subject 102, a detection apparatus 104 that outputs image data corresponding to the radiation that has passed through the subject 102, and radiation generation by the radiation generation apparatus 101. A mechanism control device 105 that controls timing and radiation generation conditions, a data collection device 106 that collects various digital data, and an information processing device 107 that controls image processing and overall equipment according to user instructions.

  The information processing device 107 includes an input signal analysis device (estimation device) 108, an afterimage correction device 109, an image processing device 110, a CPU 112, a memory 113, an operation panel 114, a storage device 115, and a display device 116. It has. These are electrically connected via the CPU bus 111.

  The memory 113 stores various data necessary for processing by the CPU 112, and includes a work memory for the CPU 112. Further, the CPU 112 uses the memory 113 to perform operation control of the entire apparatus in accordance with a user instruction input to the operation panel 114.

  In the present invention, the term “radiation” is not limited to X-rays that are generally used, but includes α-rays, β-rays, and γ-rays that are beams formed by particles (including photons) emitted by radioactive decay. In addition, a beam having the same or higher energy, such as a particle beam or a cosmic ray, is also included. Hereinafter, a case where X-rays are used as radiation will be described as an example.

  Next, a configuration example of the detection device 104 according to the present invention will be described with reference to FIG. FIG. 2 is an equivalent circuit diagram illustrating a circuit configuration of the detection device 104. Here, an example in which pixels of 3 rows and 3 columns are provided is shown, but the number of pixels is not limited to this.

  The detection device 104 includes a readout circuit 201, a power supply circuit 202, a gate drive circuit 203, and an imaging region 204 in which a plurality of pixels are arranged two-dimensionally. The pixel is composed of a photoelectric conversion element and a switch element. The pixel converts the X-ray signal input with the switch turned on to charge, accumulates an amount of charge corresponding to the signal amount (hereinafter referred to as accumulation operation), then turns the switch off and turns the signal line It has a function that can read out the electric charge from.

  The switch element includes a thin film transistor (TFT) having an active region made of a semiconductor such as amorphous silicon or polycrystalline silicon (preferably polycrystalline silicon). Here, the detection device 104 is characterized in that the pixels are roughly divided into pixels having two types of functions. One is a first pixel 213 for acquiring image information, and the other is a second pixel 214 arranged to be scattered for input signal analysis. The first pixel 213 detects radiation and reads out a radiation signal at a predetermined frame rate. The second pixel 214 reads out the radiation signal at a higher frame rate than the first pixel 213.

  The first pixels 213 are two-dimensionally arranged, and the second pixels 214 are included in the two-dimensional arrangement. The input signal analysis device (estimation device) 108 estimates the amount of radiation signal that exceeds the saturation signal amount of the first pixel 213 using the radiation signal read by the second pixel 214.

  The readout circuit 201 includes an A / D converter 205, a multiplexer 206, and a sample hold circuit 212, and each pixel can convert an input signal into an electric charge and then convert it into a digital value.

  The image signal converted into digital data by the A / D converter 205 is collected and arranged in an image format by the data collection device 106 and then output to the information processing device 107.

  Here, the sample hold circuits 212 are connected to the first signal line 207 and the second signal line 208, respectively. A first signal line 207 is connected to the first pixel 213, and a second signal line 208 is connected to the second pixel 214, and a dedicated sample and hold circuit receives signals from each pixel. Can be entered.

  A bias wiring 209 is connected to the power supply circuit 202 so that the same bias voltage is applied to each pixel.

  A gate wiring is connected to each pixel row from the gate driving circuit 203, and a signal for controlling the switch of each pixel for each row is controlled. The detection device 104 includes two kinds of a first gate wiring 210 connected to the first pixel 213 and a second gate wiring 211 connected to the second pixel 214, and includes the first pixel 213 and the first gate wiring 211. It is possible to operate the switch independently for each of the two pixels 214.

  With the above structure, the second pixel 214 can read a signal at a timing different from that of the first pixel 213. For example, the second pixel 214 is operated at a higher frame rate than the first pixel 213, and the input signal is subdivided into a plurality of times more frequently than the first pixel 213, and then the input signals are summed. . As a result, the input signal can be acquired without causing saturation even when the sum of the input signals is so large that it exceeds the dynamic range of the A / D converter.

  Note that the arrangement ratio of the first pixel 213 and the second pixel 214 is not particularly limited. For example, it is preferable that the second pixels 214 are uniformly arranged in the pixels at a ratio such that there is one second pixel 214 with respect to the 20 × 20 first pixels 213. is there.

  Next, the operation of the radiation imaging apparatus 100 having the above-described configuration will be described using FIG. FIG. 3 is a flowchart of processing performed by the radiation imaging apparatus according to the embodiment.

In step S301, the radiation imaging apparatus 100 starts an imaging operation of the subject 102 in accordance with a user instruction. First, as the imaging conditions in the first image capturing, the distance (SID) between the radiation generating device and the detecting device, the X-ray irradiation conditions (tube voltage, tube current, irradiation time), the type of grid used and presence and the sensitivity information of the detector, and the operating temperature T of the detection device 104, a first time t ₀ when the image was captured is acquired. Time t ₀ is a time from which an afterimage is generated by the first image capturing, and is a time at which the charge transfer operation of the detection device 104 is completed accompanying the image capturing.

  In step S <b> 302, the subject 102 and the detection device 104 are irradiated with X-rays according to the above-described imaging conditions, and the detection device 104 performs a reading operation to perform first image shooting.

  In step S303, the detection device 104, the data collection device 106, and the input signal analysis device (estimation device) 108 perform input signal analysis processing (estimation processing) of the acquired image by the first image capturing. The input signal analysis device (estimation device) 108 estimates the radiation signal of the first pixel 213 using the radiation signal read by the second pixel 214. With this process, even when X-rays exceeding the dynamic range of the detection apparatus 104 are input during imaging, the input dose can be accurately estimated. Details of this processing will be described later.

  In step S304, various image processing such as noise reduction processing, enhancement processing, and gradation conversion processing by the image processing apparatus 110 is performed on the first image. The image subjected to the image processing is subjected to operations such as storage in the storage device 115 and display on the display device 116 in accordance with a user instruction.

In step S305, the second image capturing is started according to the user's instruction. Here, the data collection device 106 uses the distance (SID) between the radiation generation device and the detection device and the X-ray irradiation conditions (tube voltage, tube current, irradiation time) as the second imaging conditions. the type and presence or absence of the grid, the sensitivity information of the detector, the imaging start time t _1, to obtain an imaging completion time t _2. The shooting start time t ₁ is preferably a time when reception of an input signal associated with the second image shooting is started, and the shooting completion time t ₂ is preferably a time when reception of the input signal is completed.

  In step S306, the subject 102 and the detection device 104 are irradiated with X-rays according to the second imaging condition, and the second image is captured.

  In step S307, an afterimage correction process is performed on the second image. The afterimage correction device 109 corrects the afterimage of the radiation image based on the radiation signal estimated by the input signal analysis device (estimation device) 108.

  Here, an outline of the afterimage generated by the first image capturing will be described with reference to FIG. FIG. 4 plots the afterimage amount on the vertical axis and the elapsed time on the horizontal axis, and shows the temporal change in the afterimage amount after the first image is captured.

According to the inventors' experiment, it has been found that the amount of the afterimage generated by the first image photographing draws an attenuation curve 401 with time as a parameter. Here, the afterimage generated in the second image becomes an integral 402 of the signal superimposed during the time t ₂ −t ₁ required for imaging. Based on this, the afterimage component L (x, y) of the coordinates (x, y) in the second image is estimated based on the following equation (1).

  Here, A (x, y) is an initial afterimage amount at coordinates (x, y), and k (T) is an attenuation coefficient peculiar to the detection device 104 and is a value that varies depending on the operating temperature T. . The initial afterimage amount A (x, y) is proportional to the signal input in the first image capturing, and is calculated based on the following equation (2).

  Here, α and β are constants specific to the detection device, and D (x, y) is an image showing the input signal that has reached the coordinates (x, y) in the detection device 104. A method for calculating the estimated input signal image D will be described later. Note that it is desirable that the attenuation coefficient k (T) peculiar to the detection device 104 is acquired in advance before shooting, and an appropriate value is substituted according to shooting conditions. Afterimage correction processing is performed by subtracting the afterimage component L (x, y) estimated by the above equations (1) and (2) from the second image.

  As described above, the afterimage correction apparatus 109 has an initial afterimage amount estimated by the input signal analysis apparatus (estimation apparatus) 108, the operating temperature of the detection apparatus, the attenuation coefficient unique to the detection apparatus, and the radiation signal. Is corrected by subtracting the afterimage component from the radiation image by estimating the afterimage component at the time of the previous imaging using the time when the readout of the radiation signal is started and the time when the readout of the radiation signal is completed.

  In step S308, various image processing such as noise reduction processing, enhancement processing, and gradation conversion processing by the image processing apparatus 110 is performed on the second image. The image subjected to the image processing is subjected to operations such as storage in the storage device 115 and display on the display device 116 in accordance with a user instruction.

  In the above example, the processing when two images are continuously captured is shown. However, the number of captured images is not limited to this, and afterimage correction processing is similarly performed when three or more images are captured. It is possible. In that case, it is desirable that afterimage estimation is performed on all the captured images in consideration of the superposition of the afterimages, and an accumulation of afterimages derived from the respective captured images is used for correction.

  Next, details of the input signal analysis processing will be described with reference to FIGS. FIG. 5 is a flowchart of the input signal analysis process.

  In step S501, the number N of readouts of the second pixels 214 is set according to the shooting conditions. The second pixel 214 reads out the radiation signal at the number of times of reading N greater than that of the first pixel 213 during the radiation signal readout time of the first pixel 213.

  As the imaging conditions, as in S301 described above, the distance (SID) between the radiation generation device and the detection device, the X-ray irradiation conditions (tube voltage, tube current, and irradiation time), and the grid used And the sensitivity information of the detector are used.

  From this, an approximate number of input signal amounts is estimated, and the number of times that the input signal amount in one readout does not exceed the dynamic range of the A / D converter of the second pixel 214 is set to a minimum or close number of times. It is desirable to set as the number of times of reading N. The number N of readouts may be set based on a value obtained by dividing the approximate number of estimated input signal amounts by the dynamic range of the A / D converter of the second pixel 214. In this way, the second pixel 214 sets the number of times N of reading the second pixel 214 so that the radiation signal is read in an amount that does not exceed the saturation signal amount of the second pixel 214.

  In step S502, the image capturing operation of the detection device 104 is started in synchronization with the X-ray irradiation timing. The first pixel 213 and the second pixel 214 start reading the radiation signal substantially simultaneously.

  In step S503, the photographing operation of the first pixel 213 is performed. The first pixel 213 sets an accumulation time longer than the irradiation time of the input X-ray, and operates so that all input signals can be read out by one reading. When the input signal exceeds the dynamic range of the first pixel 213, saturation occurs, and there is a possibility that a part of information with a large amount of signal is lost.

  In steps S504 to S507, the photographing operation of the second pixel 214 is performed. First, in step S504, the counter is reset. In step S505, the second pixel 214 is read out, and the output image is transferred to the input signal analyzer 108. This operation is repeated N times (steps S506 and S507).

  Here, details of a signal acquired by the second pixel 214 will be described with reference to FIG. FIG. 6 is a schematic diagram of signals output from pixels when X-rays are uniformly input to the detection device 104. FIG. 6A is a schematic diagram of an output signal of the first pixel 213. FIG. 6B is a schematic diagram of the output signal of the second pixel 214. FIG. 6C is a schematic diagram of the sum and loss of the output signal of the second pixel 214.

  As shown in FIG. 2, in the detection device 104, since the signal lines 207 and 208 are shared by each column, the charge transfer of the pixel signal and the operation of converting into a digital value are performed for each row. There is a need to do.

  Here, the first pixel 213 is characterized in that the input X-ray is read out once. Therefore, the accumulation operation is performed in all columns from the start to the end of the X-ray input, and the read operation can be started after the input of the X-ray is completed. As shown in FIG. 6A, the output 601 of the first pixel 213 when X-rays are uniformly input is constant in all columns.

  On the other hand, as shown in FIG. 6B, the second pixel 214 is characterized in that the inputted X-rays can be read out in multiple portions. As shown in FIG. 6C, the input signal analysis device (estimation device) 108 adds the radiation signal read out by the second pixel 214 during the radiation signal readout time of the first pixel 213, thereby An amount of radiation signal exceeding the saturation signal amount of 213 is estimated.

  If the time required for a pixel to transfer a pixel signal is ts, the second pixel 214 cannot perform an X-ray signal accumulation operation during that time. Therefore, as shown in FIG. 6C, the total output 602, which is the sum of the outputs from the first read to the Nth read, is the first pixel when the X-ray signal accumulation operation is performed at a time other than the transfer operation. Compared to the output 601 of 213, there is a signal loss (ts × N).

  The input signal analysis device (estimation device) 108 corrects the estimated radiation signal based on the time required to read out the radiation signal of the second pixel 214. Further, the input signal analysis device (estimation device) 108 corrects the estimated radiation signal based on the number N of radiation signal readouts of the second pixel 214 during the radiation signal readout time of the first pixel 213.

  Based on the above, in step S508, the output images of the N second pixels 214 sent to the input signal analyzing apparatus 108 are added to calculate an added image Isum.

  In step S509, processing for correcting the signal loss (ts × N) is performed on the added image Isum, and a corrected image Icor is calculated. This correction is based on the assumption that the X-ray signal is emitted at a constant intensity during the irradiation time, and the X-ray irradiation time (from the first readout time) is determined based on the imaging conditions in the first image acquisition acquired in step S301. This is performed according to the following equation (3) using tx (during the N-th reading). The coordinates (i, j) indicate the coordinates where the second pixel 214 is arranged.

In step S510, an estimated input signal image D is created from the image I1 of the _first pixel 213 and the Icor information obtained in S509. A method of creating the estimated input signal image D is performed according to the flowchart of FIG. The input signal analysis device (estimation device) 108 replaces the radiation signal read by the first pixel 213 that has exceeded the saturation signal amount with the estimated radiation signal (including the radiation signal in which the signal loss is corrected).

  FIG. 7A is a diagram illustrating an example of a pixel arrangement of the detection device 104. Here, in the detection device 104, a case where the second pixels 214 are evenly arranged at a ratio of one C × C pixel of the first pixels 213 is considered. In this figure, the second pixel 214 is arranged at a ratio of one C × C pixel at coordinates (i−C, j−C), etc., centering on coordinates (i, j).

  FIG. 7B is a flowchart of processing for creating the estimated input signal image D.

  In step S701, first, it is determined whether at least one value of the four first pixels 213 adjacent to the periphery of the coordinates (i, j) of the second pixel 214 is saturated. If at least one of the surrounding four first pixels 213 is saturated, the process proceeds to step S702; otherwise, the process proceeds to step S703.

  In step S702, the first pixel 213 saturated in the region of the first pixel 213 (the divided region 700 in FIG. 7A) having C × C pixels around the coordinates (i, j) of the second pixel 214 is obtained. The value is replaced with the value of the second pixel 214 at coordinates (i, j).

  As described above, when the radiation signal of the first pixel 213 adjacent to the second pixel 214 exceeds the saturation signal amount, the input signal analysis device 108 is within a predetermined range (C × C pixel) from the second pixel 214. The radiation signal of the first pixel 213 arranged in () is replaced with the estimated radiation signal. As a result, it is possible to appropriately obtain information on the arrival dose that has been saturated and lost in the first pixel 213.

  Step S703 is a case where saturation does not occur in the first pixel 213 and the value of the first pixel 213 can be used as it is. In this case, for example, as the value of the second pixel 214 at the coordinates (i, j), the average of the surrounding four pixels is substituted as in Expression (4).

  As described above, the input signal analysis device (estimation device) 108 outputs the radiation signal of the second pixel 214 when the radiation signal of the first pixel 213 adjacent to the second pixel 214 does not exceed the saturation signal amount. Then, the average of the radiation signals of the adjacent first pixels 213 is replaced.

  Note that the value of the second pixel 214 at the coordinates (i, j) may be used as it is without being replaced with the surrounding pixels.

  In step S704, the first pixel 213 that is saturated in the region of the first pixel 213 having C × C pixels around the second pixel 214 at the coordinates (i, j) (the divided region 700 in FIG. 7A) is obtained. It is judged whether there is. If there is a saturated first pixel 213, the saturated first pixel 213 is a second pixel 214 in which at least one of the surrounding four first pixels 213 is saturated, Replace with the value of the nearest second pixel 214.

  In this way, the input signal analysis device 108 is within a predetermined range from the second pixel 214 (C × when the radiation signal of the first pixel 213 adjacent to the second pixel 214 does not exceed the saturation signal amount. The radiation signal of the first pixel 213 arranged in the (C pixel) is replaced with the radiation signal of another second pixel around the second pixel 214. In the present embodiment, the other second pixels 214 are the second pixels 214 closest to the saturated first pixel 213 among the eight second pixels 214 around the coordinates (i, j). It is. Then, it is assumed that the radiation signal of the first pixel 213 adjacent to the other second pixel 214 exceeds the saturation signal amount.

  Note that if there are no second pixels 214 in which at least one of the four surrounding first pixels 213 is saturated in the eight second pixels 214 around the coordinates (i, j), they are saturated in the divided region 700. The value of the first pixel 213 may be used as it is without being replaced.

  With the above configuration, the radiographic apparatus according to the present invention can appropriately obtain an input signal even when the dynamic range of the A / D converter is input. As a result, it is possible to provide a radiation imaging apparatus capable of realizing a highly accurate afterimage correction process without additionally acquiring afterimage data.

  As mentioned above, although preferred embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to these Examples, A various deformation | transformation and change are possible within the range of the summary.

  The present invention also supplies a software program that implements the functions and processes of the embodiment directly (or remotely) to the system or apparatus, and the system or apparatus computer reads out and executes the supplied program code. In some cases, it can be achieved by

DESCRIPTION OF SYMBOLS 100 Radiography apparatus 101 Radiation generator 102 Subject 103 Bed 104 Detection apparatus 105 Mechanism control apparatus 106 Data collection apparatus 107 Information processing apparatus 108 Input signal analysis apparatus (estimation apparatus)
109 Afterimage correction device 110 Image processing device 111 CPU bus 112 CPU
113 Memory 114 Operation Panel 115 Storage Device 116 Display Device 201 Reading Circuit 202 Power Supply Circuit 203 Gate Drive Circuit 204 Imaging Area 205 A / D Converter 206 Multiplexer 207 First Signal Line 208 Second Signal Line 209 Bias Wiring 210 First Gate wiring 211 Second gate wiring 212 Sample hold circuit 213 First pixel 214 Second pixel

Claims (18)

Detection means comprising: a first pixel that detects radiation and reads out a radiation signal at a predetermined frame rate; and a second pixel that detects the radiation and reads out the radiation signal at a higher frame rate than the first pixel; ,
Estimating means for estimating the radiation signal of the first pixel using the radiation signal read by the second pixel;
A radiation imaging apparatus comprising: The first pixels are two-dimensionally arranged,
The second pixel is included in the two-dimensional arrangement,
The said estimation means estimates the said radiation signal of the quantity exceeding the saturation signal amount of a said 1st pixel using the said radiation signal which the said 2nd pixel read, The Claim 1 characterized by the above-mentioned. Radiography equipment.   The radiation imaging apparatus according to claim 1, further comprising an afterimage correction unit that corrects an afterimage of a radiation image based on the radiation signal estimated by the estimation unit.   4. The method according to claim 1, wherein the second pixel reads out the radiation signal with a larger number of readouts than the first pixel in the readout time of the radiation signal of the first pixel. 5. The radiographic apparatus according to the item.   5. The read count of the second pixel is set so that the second pixel reads the radiation signal in an amount that does not exceed a saturation signal amount of the second pixel. Radiography equipment.   The radiation imaging apparatus according to claim 1, wherein the first pixel and the second pixel start reading the radiation signal substantially simultaneously.   The estimation means adds the radiation signal read out by the second pixel during the readout time of the radiation signal of the first pixel, whereby an amount of the radiation exceeding the saturation signal amount of the first pixel. The radiation imaging apparatus according to claim 1, wherein a signal is estimated.   The radiation imaging apparatus according to claim 7, wherein the estimation unit corrects the estimated radiation signal based on a time required to read out the radiation signal of the second pixel.   The said estimation means correct | amends the said radiation signal estimated based on the reading frequency of the said radiation signal of the said 2nd pixel in the reading time of the said radiation signal of the said 1st pixel. The radiographic apparatus according to 7 or 8.   The said estimation means replaces the said radiation signal which the said 1st pixel exceeding the saturation signal amount read with the estimated said radiation signal, The any one of Claim 1 thru | or 9 characterized by the above-mentioned. Radiography equipment.   The estimating means is arranged such that the first pixel disposed within a predetermined range from the second pixel when the radiation signal of the first pixel adjacent to the second pixel exceeds a saturation signal amount. The radiation imaging apparatus according to claim 1, wherein the radiation signal of a pixel is replaced with the estimated radiation signal.   The estimation means determines the radiation signal of the second pixel adjacent to the first pixel when the radiation signal of the first pixel adjacent to the second pixel does not exceed a saturation signal amount. The radiation imaging apparatus according to claim 1, wherein the radiation image is replaced with an average of the radiation signals.   The estimation means is configured to arrange the first pixel disposed within a predetermined range from the second pixel when the radiation signal of the first pixel adjacent to the second pixel does not exceed a saturation signal amount. The radiation imaging apparatus according to claim 1, wherein the radiation signal of a pixel is replaced with the radiation signal of another second pixel around the second pixel.   The radiation imaging apparatus according to claim 13, wherein the radiation signal of the first pixel adjacent to the other second pixel exceeds a saturation signal amount.   The afterimage correction means includes an initial afterimage amount at the time of previous photographing estimated by the estimation means, an operating temperature of the detection means, an attenuation coefficient unique to the detection means, and a time when reading of the radiation signal is started. 4. The afterimage component at the time of previous imaging is estimated using the time when reading of the radiation signal is completed, and the correction is performed by subtracting the afterimage component from the radiation image. Radiography equipment. Radiation generating means for generating radiation;
Detection means comprising: a first pixel that detects the radiation and reads out a radiation signal at a predetermined frame rate; and a second pixel that detects the radiation and reads out the radiation signal at a higher frame rate than the first pixel. When,
Estimating means for estimating the radiation signal in an amount exceeding the saturation signal amount of the first pixel using the radiation signal read out by the second pixel;
A radiation imaging system comprising: A first readout step of detecting radiation and reading out a radiation signal at a predetermined frame rate;
A second readout step of detecting the radiation and reading out a radiation signal at a higher frame rate than the first readout step;
Using the radiation signal read in the second readout step, estimating the radiation signal in an amount exceeding the saturation signal amount of the first readout step; and
A radiation imaging method comprising:   The program for functioning a computer as each means of the radiography apparatus of any one of Claims 1 thru | or 15.