JP2011019591A - X-ray equipment, interpolating method of lost pixel in x-ray detector, and method of creating deficit map in x-ray detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide X-ray equipment capable of executing accurate registration of deficits even if instable pixels are present, a method of interpolating lost pixels in an X-ray detector, and a method of creating a deficit map in the X-ray detector. <P>SOLUTION: The X-ray equipment includes a lost pixel detecting part 61 for measuring pixel values of respective pixels while an X-ray beam is not applied to a flat panel detector 4 and detecting lost pixels; an instable pixel detecting part 62 for detecting instable pixels by finding the dispersion of the pixel values at the time; and an interpolation processing part 64 for executing the interpolation processing for the lost pixels based on the pixel values of pixels other than the instable pixels among pixels in the vicinity of the lost pixels based on the deficit map created by the deficit map creating part 63. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an X-ray imaging apparatus, a defective pixel interpolation method in an X-ray detector, and a defect map creation method in an X-ray detector.

  As an X-ray detector used for an X-ray imaging apparatus, for example, a flat panel detector (FPD) is known. This flat panel detector has a configuration in which a conversion film such as a-Se (amorphous selenium) is deposited on a substrate on which switching elements such as TFTs are arranged in a two-dimensional array (matrix). In this flat panel detector, when an X-ray image that has passed through the subject is projected onto the conversion film, a charge signal proportional to the density of the image is generated in the conversion film. This charge signal is collected by pixel electrodes arranged in a two-dimensional array and accumulated in a capacitance (capacitor). The electric charge accumulated in the electrostatic capacitance is read out along with the operation of the switching element, and is transmitted as an electric signal to the image processing unit for image processing.

  In such an X-ray detector using a conversion film such as a-Se, defective pixels may occur in the manufacturing process. For this reason, conventionally, the calibration is performed every certain period, and the pixel value when the conversion film is uniformly irradiated to irradiate the conversion film with a certain intensity, or the conversion film is not irradiated with the X-ray. A defective pixel is detected based on the pixel value in (see Patent Document 1).

  In addition, the pixel values detected by the X-ray detector are sequentially measured over time, and the dispersion of the pixel values with respect to time is calculated based on the temporal change of the pixel values. An X-ray imaging apparatus that can be detected as a defective pixel has also been proposed (see Patent Document 2).

JP 2008-301883 A JP 2008-194152 A

  In such an X-ray detector, there are pixels that exhibit unstable behavior such that the pixel value changes with time, particularly around the defective pixels. When such an unstable pixel is not detected by calibration, this pixel is treated as a normal pixel.

  By the way, generally, after detecting a defective pixel, the defect registration is executed. This defect registration is a process of specifying the position of the defective pixel and interpolating the defective pixel. The missing pixel interpolation uses median filter processing that replaces the pixel value of the defective pixel with a median pixel from a plurality of pixels adjacent to the defective pixel, or a plurality of pixel values adjacent to the defective pixel. This is performed by conversion processing.

  In such an interpolation process step at the time of registration, the above-described unstable pixel treated as a normal pixel is also used for the interpolation process. For this reason, if an unstable pixel shows an unstable behavior during this interpolation process, a defective pixel that has been interpolated using this unstable pixel will not show an appropriate pixel value, and a large missing pixel It will appear as a lump on the image.

  On the other hand, as in the above-described Patent Document 2, when the variance of the pixel value is obtained based on the temporal change of the pixel value and a pixel that is not permanently a defective pixel is detected as a defective pixel, it is permanently Although a pixel that does not have a defect can be detected as a defective pixel, excessive correction may be performed depending on the setting of a threshold value for determining whether or not the pixel is a defective pixel. For this reason, the number of correction pixels may increase more than necessary, and there may be a case where accurate X-ray imaging cannot be performed due to disappearance of a necessary diagnostic part.

  The present invention has been made in order to solve the above-described problem. Even when unstable pixels exist, an X-ray imaging apparatus and an X-ray detector capable of performing accurate defect registration are provided. An object is to provide an interpolation method and a method for creating a defect map in an X-ray detector.

  The invention described in claim 1 includes an X-ray tube that irradiates the subject with X-rays, a conversion film sensitive to X-rays, and a two-dimensional array of detection elements that partition pixels, An X-ray imaging apparatus comprising: an X-ray detector that detects X-rays irradiated from a ray tube and passed through a subject; or the X-ray detector is not irradiated with X-rays, or the X-ray detector In a state in which uniform X-rays are irradiated, the pixel value of each pixel in the X-ray detector is measured to detect a defective pixel, and the X-ray detector is not irradiated with X-rays In the state, or in the state where the X-ray detector is irradiated with uniform X-rays, the pixel values of each pixel in the X-ray detector are measured over time to obtain the dispersion, thereby obtaining unstable pixels. Among the unstable pixel detection means for detecting, and the pixels in the vicinity of the defective pixel, Based on the pixel values of the pixels other than the stable pixels, characterized by comprising an interpolation processing means for performing an interpolation process of the defective pixel.

  According to a second aspect of the invention, in the first aspect of the invention, unstable pixel data is added to the unstable pixel detected by the unstable pixel detecting means, and the defective pixel detecting means is used. A defect map creating means for creating a defect map by adding defective pixel data including position information of a pixel to be used when performing interpolation of the defective pixel to the detected defective pixel, the interpolation processing The means performs interpolation processing of the defective pixel using the defective map.

  According to a third aspect of the present invention, in the second aspect of the present invention, the pixel to be used when interpolation of the defective pixel is in the vicinity of the defective pixel and the data of the unstable pixel is given. A pixel other than the selected pixel is selected.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the defective pixel detecting means does not irradiate the X-ray detector with X-rays or the X-rays In a state where the detector is irradiated with uniform X-rays, the pixel value of each pixel in the X-ray detector is measured over time to calculate an average value of the pixel values, and an image based on the average value of the pixel values is obtained. On the other hand, a defective pixel is detected by performing a subtraction process between the image to which the filter is applied and the image based on the average value of the pixel values.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to third aspects, the unstable pixel detecting means is configured such that a standard deviation of the pixel value of each pixel is a standard of the pixel value of each pixel. Pixels larger than a certain value or smaller than a certain value than the average deviation are detected as unstable pixels.

  The invention described in claim 6 includes a conversion film sensitive to X-rays and a two-dimensional array of detection elements for partitioning pixels, and detects X-rays irradiated from the X-ray tube and passing through the subject. In the method of interpolating a defective pixel in an X-ray detector that interpolates the defective pixel with respect to the X-ray detector, the X-ray detector is not irradiated with X-rays, or the X-ray detector has a uniform X-ray. An image obtained by measuring a pixel value of each pixel in the X-ray detector with time and calculating an average value of the pixel values and applying a filter to an image based on the average value of the pixel values A defective pixel detection step of detecting a defective pixel by performing a subtraction process between the average value of the pixel value and the image, and a state in which the X-ray detector is not irradiated with X-rays, or the X-ray detector In the state irradiated with uniform X-rays, The pixel value of each pixel in the line detector is measured over time to determine its variance, and the standard deviation of the pixel value of each pixel is a pixel greater than a certain value by an average value of the standard deviation of the pixel value of each pixel, Alternatively, an unstable pixel detection step of detecting a pixel smaller than a certain value as an unstable pixel, and a pixel value of a pixel other than the unstable pixel among pixels in the vicinity of the defective pixel is used. And an interpolation processing step for performing the interpolation processing.

  The invention described in claim 7 has a conversion film sensitive to X-rays and a two-dimensional array-shaped detection element that partitions pixels, and detects X-rays irradiated from the X-ray tube and passing through the subject. In a method for creating a defect map in an X-ray detector for creating a defect map for performing defect registration for an X-ray detector, the X-ray detector is not irradiated with X-rays, or the X-ray detection is performed In a state in which the X-ray detector is irradiated with uniform X-rays, the pixel value of each pixel in the X-ray detector is measured to detect a defective pixel, and the X-ray detector is irradiated with X-rays In a state in which the X-ray detector is not irradiated or in a state in which the X-ray detector is irradiated with uniform X-rays, the pixel value of each pixel in the X-ray detector is measured over time to obtain its dispersion, thereby obtaining unstable pixels An unstable pixel detecting step for detecting the unstable pixel and the unstable pixel An unstable pixel mapping step for mapping unstable pixels by inputting an unstable pixel code for the unstable pixels detected in the elementary detection step, and a defective pixel detected in the defective pixel detection step A defective pixel mapping step for mapping the defective pixel by inputting a correction position code indicating the position of the pixel to be used when performing the defective registration, and in the defective pixel mapping step, Among the pixels, a pixel to be used when performing defect registration is selected from pixels other than the pixel to which the unstable pixel code is input.

  According to the first aspect of the present invention, since the defective pixel is interpolated using the pixel values of the pixels other than the unstable pixel among the pixels in the vicinity of the defective pixel, the unstable pixel exists. In this case, it is possible to perform accurate interpolation registration by executing appropriate interpolation processing.

  According to the second aspect of the present invention, it is possible to perform proper interpolation processing and perform accurate defect registration by using a defect map to which unstable pixel data and missing pixel data are added. It becomes.

  According to the third aspect of the present invention, since a pixel to be used when performing interpolation from a pixel other than a pixel to which data of unstable pixel is added and in the vicinity of a defective pixel, an appropriate value is selected. It is possible to create a missing map that can be subjected to interpolation processing.

  According to the fourth aspect of the present invention, since the defective pixel is detected using the average value of the pixel values measured over time and the image to which the filter is applied, the influence of random noise is detected. It is possible to detect a defective pixel after removing.

  According to the fifth aspect of the present invention, a pixel in which the standard deviation of the pixel value of each pixel is larger than the average value of the standard deviation of the pixel value of each pixel or a pixel smaller than the certain value is detected as an unstable pixel. Therefore, it is possible to appropriately determine unstable pixels.

  According to the sixth aspect of the present invention, since the defective pixel is interpolated using the pixel values of pixels other than the unstable pixel among the pixels in the vicinity of the defective pixel, there is an unstable pixel. In this case, it is possible to perform accurate interpolation registration by executing appropriate interpolation processing. In addition, since defective pixels are detected using the average value of pixel values measured over time and an image obtained by applying a filter to the average value, defective pixels are detected after removing the effects of random noise. It becomes possible to do. In addition, because the standard deviation of the pixel value of each pixel is more than a certain value than the average value of the standard deviation of each pixel, or a pixel smaller than a certain value is detected as an unstable pixel, Can be determined.

  According to the seventh aspect of the present invention, mapping is performed by inputting an unstable pixel code to an unstable pixel, and correction indicating the position of the pixel to be used when performing defective registration for the defective pixel It is possible to register a defect using a defect map that has been mapped by inputting a position code. At this time, at the time of mapping the defective pixel, there is an unstable pixel because the pixel used when performing the defective registration is selected from the pixels near the defective pixel other than the pixel to which the unstable pixel code is input. Even in this case, it is possible to perform accurate interpolation registration by executing appropriate interpolation processing.

1 is a schematic diagram of an X-ray imaging apparatus according to the present invention. It is the equivalent circuit which looked at the flat panel detector 4 from the side. It is an equivalent circuit in plan view of the flat panel detector 4. It is a flowchart which shows the interpolation method of the defective pixel which concerns on this invention. It is explanatory drawing which shows the concept of the defective pixel interpolation method which concerns on this invention. It is a histogram which shows distribution of the standard deviation of each pixel. It is explanatory drawing which shows typically the defect map produced by the defect map creation process.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of an X-ray imaging apparatus according to the present invention.

  The X-ray imaging apparatus includes a table 2 on which a subject 1 as a subject is placed, an X-ray tube 3, a flat panel detector 4, an A / D converter 5, a control unit 6, and a storage unit. 7, an input unit 11 such as a keyboard, a display unit 12 such as a CRT, and an X-ray tube control unit 8 that controls a tube voltage or the like applied to the X-ray tube 3. Further, as will be described later, the control unit 6 includes a defective pixel detection unit 61 that detects a defective pixel, an unstable pixel detection unit 62 that detects an unstable pixel, and a defective map creation unit 63 that creates a defect map. And an interpolation processing unit 64 for performing interpolation processing of defective pixels.

  This X-ray imaging apparatus emits X-rays from an X-ray tube 3 toward a subject 1 on a table 2, detects X-rays passing through the subject 1 with a flat panel detector 4, and a control unit 6. The X-rays detected in the above are subjected to image processing, and an X-ray fluoroscopic image is displayed on the display unit 12 using a video signal of the image-processed X-rays.

  Next, the configuration of the flat panel detector 4 will be described. FIG. 2 is an equivalent circuit when the flat panel detector 4 is viewed from the side. FIG. 3 is an equivalent circuit of the flat panel detector 4 in plan view.

  As shown in these drawings, the flat panel detector 4 includes a glass substrate 41, a TFT (thin film transistor) 42 formed on the glass substrate 41, and a conversion film such as a-Se deposited on the TFT. 43 and a common electrode 44 disposed on the conversion film 43.

  The TFT 42 is provided with pixel electrodes 45 serving as charge collection electrodes in a matrix arrangement in the vertical and horizontal directions, that is, in a two-dimensional array. For example, 1024 × 1024 pixel electrodes 45 are arranged in the matrix direction. 2 and 3 schematically show a case where 3 × 3 are arranged in the matrix direction. A switching element 46 and a capacitance (capacitor) 47 are connected to each pixel electrode 45.

  Each pixel electrode 45 is connected to the source S of each switching element 46. A plurality of gate bus lines 52 are connected to the gate driver 51 shown in FIG. 3, and these gate bus lines 52 are connected to the gate G of the switching element 46. On the other hand, as shown in FIG. 3, a plurality of data bus lines 55 are connected via an amplifier 54 to a multiplexer 53 that collects charge signals and outputs them to one. Are connected to the drain D of each switching element 46.

  In the flat panel detector 4, when an X-ray image that has passed through the subject 1 is projected onto the conversion film 43, a charge signal (carrier) proportional to the density of the image is generated in the conversion film 43. This charge signal is collected by the pixel electrodes 45 arranged in a two-dimensional array and accumulated in the capacitance 47. Then, the gate G of each switching element 46 is turned on by applying a voltage to the gate bus line 52 by the gate driver 51 in a state where the bias voltage is applied to the common electrode 44. As a result, the charge signal accumulated in the capacitance 47 is read out to the data bus line 55 via the source S and drain D in the switching element 46. The charge signals read to the data bus lines 55 are amplified by the amplifiers 54 and are combined into one charge signal by the multiplexer 53 and output. This charge signal is digitized by the A / D converter 5 and output to the control unit 6 shown in FIG. 1 as an X-ray detection signal.

  In the flat panel detector 4 having such a configuration, a defective pixel based on the characteristics of the conversion film 43 made of a-Se or the like may occur in the manufacturing process. Further, when the use of the flat panel detector 4 is continued, a defect due to a change with time of the characteristics of the conversion film 43 may occur. For this reason, the calibration of the flat panel detector 4 is executed every predetermined period, and the defect registration including the interpolation process of the defective pixel is executed by the method for interpolating the defective pixel according to the present invention.

  Next, a defective pixel interpolation method according to the present invention will be described. FIG. 4 is a flowchart showing a method for interpolating missing pixels according to the present invention. FIG. 5 is an explanatory diagram showing the concept of the defective pixel interpolation method according to the present invention.

  When calibration is performed in order to perform defect registration for confirming a defective pixel and performing interpolation, a dark current value is first measured (step S1). When measuring the dark current value, the defective pixel detector 61 shown in FIG. 1 sequentially turns the switching elements 46 shown in FIGS. 2 and 3 while the conversion film 43 in the flat panel detector 4 is not irradiated with X-rays. Based on the charge signal read out by the data bus line 55 when the on state is established, the pixel value of each pixel is sequentially measured as a dark current value. The measurement of the dark current value is performed for each pixel (for example, every 1024 × 1024 pixels) at a constant imaging cycle. Then, a plurality of frames of images Mi shown in FIG. 5 are acquired based on the dark current value of each pixel.

  In this embodiment, the dark current value is measured in a state where the flat panel detector 4 is not irradiated with X-rays. Instead, uniform X-rays are applied to the flat panel detector 4. You may measure the electric current value when irradiated. That is, at the time of this calibration, it is only necessary to measure the pixel value when each pixel of the flat panel detector 4 has the same condition.

  Next, an averaging process step is executed (step S2). In this averaging processing step, images Mi of a plurality of frames based on dark current values are averaged between frames. That is, as shown in FIG. 5, the average value (xa) of the pixel values (xi) of the pixels at the same position is obtained for each image of each frame Mi. Then, an image Ma having the average value (xa) of the pixel values is obtained. This image Ma, that is, the average value (xa) of the dark current value in each pixel is stored in the storage unit 7. In this way, by performing the averaging process on a plurality of frames of images, it is possible to remove the influence of random noise, and pixels that are not always determined to be missing but appear as defects on the image. Can be recognized.

  Next, a median filter is applied to the image Ma having this average value (xa) (step S3). In this case, for example, an N × 1 median filter and a 1 × N median filter are applied to the image Ma having an average pixel value (xa) in directions orthogonal to each other. Then, subtraction processing is performed between the image obtained by applying the median filter to the image Ma having the average pixel value (xa) and the image Ma having the average pixel value (xa) (step S4). Thereafter, a pixel having a protruding pixel value after the subtraction process is determined as a defective pixel (step S5). Information on the determined defective pixel is stored in the storage unit 7 shown in FIG.

  In the above-described embodiment, the target image is extracted by applying an N × 1 median filter and a 1 × N median filter in directions orthogonal to each other. As described above, when the median filter having one row or one column is used, the filter processing can be executed at high speed. And, by applying these filters to the directions orthogonal to each other and filtering the entire image, the time required for filtering is greatly reduced compared to the case of using an N × N median filter. It becomes possible to do.

  In the above-described embodiment, the median filter is used for the filter processing. However, other filters such as a low-pass filter may be applied instead of the median filter.

Next, a variance calculation is performed on the pixel value (xi) of each frame Mi (step S6). This calculation is executed by the unstable pixel detection unit 62 shown in FIG. 1, and the variance (σ ² ) of the pixel value (xi) of the pixel at the same position is obtained. When obtaining this variance (σ ² ), the following equation (1) is used.

ここで、画素の平均値（ｘａ）は下記の式（２）で表される。

Here, the average value (xa) of the pixels is expressed by the following equation (2).

Next, unstable pixels are determined based on the variance (σ ² ) obtained in the variance calculation processing step (step S6) (step S7). This unstable pixel determination is performed by the unstable pixel detection unit 62 shown in FIG.

FIG. 6 is a histogram showing the standard deviation distribution of each pixel. In this figure, the horizontal axis represents the standard deviation (σ) obtained from the variance (σ ² ), and the vertical axis represents the frequency of each pixel (for example, the frequency for 1020 × 1020 frequencies).

  This histogram is considered to have a substantially normal distribution, and the standard deviation of normal pixels is concentrated around the average value of the standard deviation. An unstable pixel whose pixel value changes with time has a value whose standard deviation is considerably larger or smaller than that of a normal pixel. For this reason, the unstable pixel detection unit 62 determines, as unstable pixels, a pixel whose standard deviation is greater than or equal to a preset threshold E and a pixel smaller than the threshold E than the average value of standard deviations. Information on the determined unstable pixels is stored in the storage unit 7 shown in FIG.

The threshold value E is obtained experimentally in advance. The threshold value E may be determined based on the standard deviation of the spatial distribution of the previously obtained variance (σ ² ), as described in Patent Document 2 described above.

  Next, based on the defective pixel determined in the defective pixel determination step (step S5) and the unstable pixel determined in the unstable pixel determination step (step S7), the defective map that maps the defective pixel and the unstable pixel is performed. A creation process is executed (step S8). This missing map creating step is executed by the missing map creating unit 63 shown in FIG. This missing map creation process includes an unstable pixel mapping process and a missing pixel mapping process.

  FIG. 7 is an explanatory diagram schematically showing the defect map created by the defect map creating step (step S8). In this figure, the rectangle with the symbol A indicates the defective pixel determined in the defective pixel determination step (step S5), and the rectangle with the symbol B is determined in the unstable pixel determination step (step S7). An unstable pixel is shown, and a rectangle without a symbol indicates a normal pixel. Moreover, the arrow in this figure has shown the normal pixel of the interpolation object used in order to interpolate a missing pixel.

  In the unstable pixel mapping step in the defect map creation step, unstable pixel mapping is performed by inputting an unstable pixel code to the unstable pixel detected in the unstable pixel determination step (step S7). On the other hand, in the defective pixel mapping step in the defective map creation step, a correction position code indicating the position of the pixel to be used when performing defective registration is input to the defective pixel detected in the defective pixel determination step (step S5). By doing so, the defective pixel is mapped.

  At this time, as pixels to be used when performing defect registration for the defective pixel, pixels other than the unstable pixel to which the unstable pixel code is input among the pixels near the defective pixel are used. That is, in a general interpolation process, a median filter process or a replacement process is performed on a missing pixel by using a pixel value of a pixel near the missing pixel. However, in the defective pixel interpolation method according to the present invention, as shown in FIG. 7, normal pixels in the vicinity excluding unstable pixels and defective pixels are used among a plurality of pixels near the defective pixels.

  Note that the embodiment shown in FIG. 7 shows a case where interpolation processing is performed from two neighboring pixels. However, the interpolation process may be performed using two or more normal pixels. Further, in FIG. 7, normal pixels selected for three defective pixels among the nine defective pixels are shown.

  If a pixel to be used when performing defect registration in this way is determined, a correction position code indicating the position of the pixel is input to the missing pixel. The determination of the pixel to be used when performing the defect registration and the input operation of the correction position code indicating the position of the pixel are executed by the defect map creating unit 63 shown in FIG.

  If a missing map is created in the missing map creation step (step S8) in this way, an interpolation processing step is executed using this missing map (step S9). In this interpolation processing step, the missing pixels in the missing map created in the missing map creating step (step S8) are interpolated using normal pixels selected based on the correction position code input thereto. As this interpolation processing, a known interpolation method such as the median filter processing or replacement processing described above is employed.

  In this interpolation processing step, the unstable pixel detected in the unstable pixel determination step (step S7) is not subjected to interpolation processing as in the normal pixel. For this unstable pixel, interpolation processing is executed when it is determined as a missing pixel during the next calibration. An unstable pixel has a high possibility of transitioning to a defective pixel over time. For this reason, the time for replacement of the flat panel detector 4 may be predicted by specially monitoring the unstable pixels.

DESCRIPTION OF SYMBOLS 1 Subject 2 Table 3 X-ray tube 4 Flat panel detector 6 Control part 7 Memory | storage part 8 X-ray tube control part 11 Input part 12 Display part 41 Glass substrate 42 TFT
43 Conversion Film 44 Common Electrode 45 Pixel Electrode 46 Switching Element 47 Capacitance 51 Gate Driver 52 Gate Bus Line 53 Multiplexer 54 Amplifier 55 Data Bus Line 61 Missing Pixel Detection Unit 62 Unstable Pixel Detection Unit 63 Defect Map Detection Unit 64 Interpolation Processing Part

Claims (7)

An X-ray tube that irradiates the subject with X-rays, a conversion film that is sensitive to X-rays, and a two-dimensional array of detection elements that divide the pixels. An X-ray imaging apparatus comprising: an X-ray detector that detects X-rays that have been performed;
In a state where the X-ray detector is not irradiated with X-rays or a state where the X-ray detector is irradiated with uniform X-rays, a pixel value of each pixel in the X-ray detector is measured, and a defective pixel is detected. Deficient pixel detection means for detecting
In a state where the X-ray detector is not irradiated with X-rays or a state where the X-ray detector is irradiated with uniform X-rays, the pixel value of each pixel in the X-ray detector is measured over time. Unstable pixel detection means for detecting unstable pixels by obtaining the dispersion; and
Interpolation processing means for performing interpolation processing of the defective pixel based on pixel values of pixels other than the unstable pixel among pixels in the vicinity of the defective pixel;
An X-ray imaging apparatus comprising: The X-ray imaging apparatus according to claim 1,
Data for unstable pixels is added to the unstable pixels detected by the unstable pixel detection means, and is used when interpolation of defective pixels is performed for the defective pixels detected by the defective pixel detection means. A defect map creating means for creating a defect map by giving data of a defective pixel including position information of a pixel to be corrected;
The X-ray imaging apparatus, wherein the interpolation processing means performs interpolation processing of the defective pixel using the defect map. The X-ray imaging apparatus according to claim 2,
An X-ray imaging apparatus in which a pixel to be used when performing interpolation of the defective pixel is selected from pixels other than the pixel to which the unstable pixel data is assigned in the vicinity of the defective pixel. The X-ray imaging apparatus according to any one of claims 1 to 3,
The defective pixel detection means has a pixel value of each pixel in the X-ray detector in a state where the X-ray detector is not irradiated with X-rays or in a state where the X-ray detector is irradiated with uniform X-rays. Is measured over time to calculate the average pixel value,
An X-ray imaging apparatus that detects a defective pixel by performing a subtraction process between an image obtained by applying a filter to an image based on an average pixel value and an image based on an average pixel value. The X-ray imaging apparatus according to any one of claims 1 to 3,
The unstable pixel detecting means detects a pixel having a standard deviation of a pixel value of each pixel that is larger than a certain value or smaller than a mean value of standard deviations of pixel values of each pixel as an unstable pixel. X-ray equipment. An X-ray detector that has a conversion film sensitive to X-rays and a two-dimensional array of detection elements that divide pixels, and that is deficient with respect to an X-ray detector that detects X-rays irradiated from the X-ray tube and passing through the subject. In a method for interpolating a defective pixel in an X-ray detector that interpolates a pixel,
In a state where the X-ray detector is not irradiated with X-rays or a state where the X-ray detector is irradiated with uniform X-rays, the pixel value of each pixel in the X-ray detector is measured over time. A defective pixel that calculates an average pixel value and detects a defective pixel by performing a subtraction process between an image obtained by applying a filter to an image based on the average pixel value and an image based on the average pixel value A detection process;
In a state where the X-ray detector is not irradiated with X-rays or a state where the X-ray detector is irradiated with uniform X-rays, the pixel value of each pixel in the X-ray detector is measured over time. An unstable pixel that obtains the variance and detects a pixel whose standard deviation of the pixel value is greater than or equal to a certain standard deviation of the pixel value of each pixel or a pixel that is smaller than a certain value as an unstable pixel. A detection process;
An interpolation process step of performing an interpolation process of the defective pixel by using a pixel value of a pixel other than the unstable pixel among the pixels in the vicinity of the defective pixel;
A method for interpolating defective pixels in an X-ray detector, comprising: An X-ray detector that has a conversion film sensitive to X-rays and a two-dimensional array of detection elements that divide pixels, and is deficient with respect to an X-ray detector that detects X-rays that have been irradiated from the X-ray tube and passed through the subject. In a method for creating a defect map in an X-ray detector that creates a defect map for registration,
In a state where the X-ray detector is not irradiated with X-rays or a state where the X-ray detector is irradiated with uniform X-rays, a pixel value of each pixel in the X-ray detector is measured, and a defective pixel is detected. A defective pixel detection step for detecting
In a state where the X-ray detector is not irradiated with X-rays or a state where the X-ray detector is irradiated with uniform X-rays, the pixel value of each pixel in the X-ray detector is measured over time. An unstable pixel detection step for detecting unstable pixels by obtaining the variance;
An unstable pixel mapping step for mapping unstable pixels by inputting an unstable pixel code to the unstable pixels detected in the unstable pixel detection step;
A defective pixel mapping step of mapping a defective pixel by inputting a correction position code indicating a position of a pixel to be used when performing defective registration with respect to the defective pixel detected in the defective pixel detection step. ,
X-ray characterized in that, in the defective pixel mapping step, a pixel to be used when performing defective registration is selected from pixels other than the pixel to which the unstable pixel code is input among pixels near the defective pixel. How to create a defect map in the detector.

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