JP4853314B2 - Radiation imaging device - Google Patents

Description

  The present invention relates to a radiation imaging apparatus used in the medical field, industrial fields such as non-destructive inspection, RI (Radio isotope) inspection, optical inspection, and nuclear power field, and more particularly to a technique for detecting a defective pixel.

  Taking X-rays as an example, image processing in a radiation imaging apparatus is performed based on radiation detected by radiation detection means typified by a flat panel radiation detector (FPD). The FPD described above is configured by stacking a sensitive film on a substrate, detecting radiation incident on the sensitive film, converting the detected radiation into electric charges, and arranging the two-dimensional array. Charge is stored in the capacitor. The accumulated charge is read by turning on the switching element and sent to the image processing unit as an electrical signal for image processing. Therefore, there is a variation in the amount of charge accumulated for each detection element that constitutes the capacitor or the switching element, and thereby there is also a variation in the pixel value based on the electrical signal for each detection element.

  In particular, when it does not function as a detection element, the pixel value becomes extremely large and appears white on the image, or the pixel value becomes extremely small and becomes black on the image. When the sensitivity of the detection element is high, dark current is generated even when no radiation is incident, and the pixel value increases. Conversely, when the sensitivity of the detection element is low, or when dust or the like adheres to the detection element, the pixel value becomes small. A pixel having such a value is called a “missing pixel”.

  As a method of interpolating a defective pixel, there are a median filter process that replaces a defective pixel with a median pixel from a plurality of pixels adjacent to the defective pixel, an interpolation process that interpolates a pixel based on the adjacent pixel, and the like (for example, , See Patent Document 1 and Patent Document 2). In addition, a series of operations for detecting and interpolating missing pixels (this operation is hereinafter also referred to as “missing registration”) is performed every predetermined period (for example, one month).

In order to reduce missing pixels, there is calibration other than missing registration. In the calibration, in order to eliminate variations, for example, the gain of an amplifier (amplifier) for each detection element is adjusted to align the output side. For missing registration in a period shorter than the predetermined period, the missing pixel is detected using the data of the calibrated pixel (see, for example, Patent Document 3).
JP 2000-284059 A (page 2-4, FIG. 2-4) JP 2000-135210 A (page 4-9, FIGS. 3 and 4) Japanese Patent Laying-Open No. 2005-270552 (page 3-8, FIG. 5-8)

  However, with respect to the defective pixel, there are pixels that are not always determined as defective pixels but are recognized as defective on the image, in addition to pixels that are constantly defective. That is, at a certain point in time, it is determined that the pixel value is not a defective pixel at the same level as the surrounding pixel values, and at a certain point in time, the pixel value is extremely large / smaller than the surrounding pixel value and is determined to be a defective pixel. Pixels exist. For this pixel, for example, the appearance rate changes depending on the length of the X-ray irradiation time in the X-ray diagnostic apparatus. Therefore, it cannot be detected even by a method for detecting a defective pixel using data of a pixel that has been calibrated as in Patent Document 3, which seems to have the highest accuracy among the conventional techniques.

  This invention is made in view of such a situation, Comprising: It aims at providing the radiation imaging device which can detect a defect | deletion pixel appropriately.

In order to achieve such an object, the present invention has the following configuration.
That is, the invention described in claim 1 includes a radiation detection unit that detects radiation that has passed through the subject, and a defective pixel detection unit that detects a defective pixel for a pixel value based on the detected signal . A radiation imaging device that images a subject by performing image processing based on radiation, and sequentially collects pixel values based on signals detected in a non-irradiation state or a radiation irradiation state of constant intensity over time. And a statistic calculation unit that obtains a time variance , which is a variance related to the time of the pixel value, as a statistic of the temporal change of the pixel value based on the temporal change of the pixel value collected by the pixel value collection unit When, a spatial distribution calculating means for determining the spatial distribution of the time dispersion of each respective pixel, the predetermined range of spatial distribution of time dispersion for each pixel of each determined by the spatial distribution calculating means Constant to said defective pixel detecting means time variance of pixel deviated from the predetermined range is characterized in that the detection as the defective pixel.

[Operation / Effect] According to the first aspect of the present invention, the pixel value collecting means sequentially collects pixel values based on signals detected in a non-irradiation state or a radiation irradiation state of a constant intensity with time. Based on the temporal change of the pixel value collected by the pixel value collecting means, the statistical quantity calculating means obtains the statistical value of the temporal change of the pixel value. Since the statistic of the temporal change of the pixel value obtained in this way also serves as an index representing the history of the temporal change of the pixel value, the defective pixel detection means is also used based on the statistic for the pixel that is not permanently defective. Can properly detect defective pixels.
Further, the statistic of the temporal change of the pixel value obtained by the above-described statistic calculating means is a temporal variance that is a variance of the pixel value with respect to time, and the apparatus obtains a spatial distribution of the temporal variance for each pixel. A spatial distribution calculating means, wherein a predetermined range is set from the spatial distribution of the time dispersion for each pixel obtained by the spatial distribution calculating means, and the defective pixel detecting means detects the temporal dispersion pixels outside the predetermined range. It detects as a pixel. That is, by considering the spatial distribution for each pixel constituting the image, it is possible to detect a defective pixel as compared with surrounding pixels.

In the above-described invention, in order to interpolate the defective pixel detected by the defective pixel detecting means, it is preferable to include a defective pixel interpolating means for interpolating the defective pixel detected by the defective pixel detecting means. Described invention). Based on the radiation detected by the radiation detecting means, by performing the interpolation of the defective pixel in the defective pixel interpolation means performs imaging of the subject.

  In particular, when the spatial distribution of time dispersion for each pixel is represented by a histogram relating to time dispersion for each pixel, the histogram can be regarded as a substantially normal distribution, and thus a predetermined range of the histogram (for example, a space relating to time dispersion). A pixel having a time dispersion that is out of the range of + several times the standard deviation of the distribution or a range of ± several times) can be regarded as being different from other surrounding pixels. Therefore, the defective pixel detecting means can appropriately detect such a pixel as a defective pixel.

According to the radiation imaging apparatus according to the present invention, the statistic of the pixel value temporal change also serves as an index representing the history of the pixel value temporal change, and therefore, even for pixels that are not permanently missing pixels, based on the statistic. Thus, the defective pixel detection means can appropriately detect the defective pixel.
Further, the statistic of the temporal change of the pixel value is a temporal dispersion that is a dispersion of the pixel value with respect to time, and a predetermined range is set from the spatial distribution of the temporal dispersion for each pixel obtained by the spatial distribution calculating means. The defective pixel detection means detects the pixel of time dispersion outside the predetermined range as the defective pixel. That is, by considering the spatial distribution for each pixel constituting the image, it is possible to detect a defective pixel as compared with surrounding pixels.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram of an X-ray diagnostic apparatus according to the embodiment, FIG. 2 is a block diagram showing a specific configuration of an image processing unit used in the X-ray diagnostic apparatus, and FIG. FIG. 4 is an equivalent circuit of a flat panel X-ray detector used in the X-ray diagnostic apparatus as viewed from the side, and FIG. 4 is an equivalent circuit of the flat panel X-ray detector as viewed from above. In this embodiment, a flat panel X-ray detector (hereinafter referred to as “FPD” as appropriate) is taken as an example of radiation detection means, and an X-ray diagnostic apparatus is taken as an example of a radiation imaging apparatus.

  As shown in FIG. 1, the X-ray diagnostic apparatus according to the present embodiment includes a top plate 1 on which a subject M is placed, an X-ray tube 2 that irradiates the subject M with X-rays, and a subject. FPD3 which detects the X-ray which permeate | transmitted M is provided. The FPD 3 corresponds to radiation detection means.

  In addition, the X-ray diagnostic apparatus further includes the top panel control unit 4 that controls the elevation and horizontal movement of the top panel 1, the FPD control unit 5 that controls the scanning of the FPD 3, and the tube voltage and tube current of the X-ray tube 2. An X-ray tube control unit 7 having a high voltage generation unit 6 to be generated, an A / D converter 8 that digitizes and extracts an X-ray detection signal that is a charge signal from the FPD 3, and an A / D converter 8 In addition to performing various processes based on the X-ray detection signal, collection of pixel values to be described later, dispersion of pixel values with respect to time (time dispersion), calculation of spatial distribution (histogram) of time dispersion for each pixel, and An image processing unit 9 that performs defect registration such as detection / interpolation of defective pixels, a controller 10 that supervises these components, a memory unit 11 that stores processed images, and an input unit in which an operator performs input settings 12 and processed And a monitor 13 for displaying images and the like.

  The top board control unit 4 horizontally moves the top board 1 to accommodate the subject M up to the imaging position, moves up and down and horizontally moves the subject M to a desired position, or performs imaging while horizontally moving the subject M. Or performing horizontal control after the completion of imaging and retreating from the imaging position. The FPD control unit 5 performs control related to scanning by moving the FPD 3 horizontally or rotating around the body axis of the subject M. The high voltage generation unit 6 generates a tube voltage and a tube current for irradiating X-rays and applies them to the X-ray tube 2. The X-ray tube control unit 7 moves the X-ray tube 2 horizontally, Control relating to scanning by rotating around the axis of the body axis of M, control of the setting of the irradiation field of the collimator (not shown) on the X-ray tube 3 side, and the like are performed. When scanning the X-ray tube 2 or the FPD 3, the X-ray tube 2 and the FPD 3 move while facing each other so that the FPD 3 can detect the X-rays emitted from the X-ray tube 2.

  The A / D converter 8 converts the charge signal output from the FPD 3 from analog to digital, and outputs a digitized X-ray detection signal. The controller 10 is configured by a central processing unit (CPU) and the like, and the memory unit 11 is configured by a storage medium represented by ROM (Read-only Memory), RAM (Random-Access Memory), and the like. Yes. The input unit 12 includes a pointing device represented by a mouse, a keyboard, a joystick, a trackball, a touch panel, and the like. In the X-ray diagnostic apparatus, the FPD 3 detects X-rays that have passed through the subject M, and the image processing unit 10 performs image processing based on the detected X-rays, thereby imaging the subject M.

  As shown in FIG. 2, the image processing unit 9 collects pixel values based on the X-ray detection signal detected in the non-irradiation state sequentially with the pixel value collecting unit 21 and the pixel value collecting unit 21. A time variance calculating unit 22 for obtaining a variance (time variance) of the pixel value as a statistic of the time change of the pixel value based on the time change of the pixel value, and the pixel value obtained by the time variance calculating unit 22 A histogram calculation unit 23 that obtains a histogram relating to time dispersion for each pixel based on the time dispersion of the pixel, and a predetermined range is set from the histogram relating to time dispersion for each pixel obtained by the histogram calculation unit 23, Missing pixel detection that detects pixels with time dispersion outside the range (for example, a range of +6 times the standard deviation of the spatial distribution related to time dispersion or a range of ± 6 times) as a missing pixel 24, is constituted by a defective pixel interpolating unit 25 for interpolating the detected defective pixel in the defective pixel detection unit 24. With these configurations, the image processing unit 9 performs defect registration, which is a series of operations for detecting and interpolating missing pixels. The pixel value collection unit 21 corresponds to the pixel value collection unit in the present invention, the time dispersion calculation unit 22 corresponds to the statistic calculation unit in the present invention, and the histogram calculation unit 23 corresponds to the spatial distribution calculation unit in the present invention. The missing pixel detector 24 corresponds to the missing pixel detector in the present invention, and the missing pixel interpolator 25 corresponds to the missing pixel interpolator in the present invention. In addition, the temporal dispersion of the pixel value corresponds to a statistic of the temporal change of the pixel value, and the histogram relating to the temporal dispersion for each pixel corresponds to the spatial distribution of the temporal dispersion for each pixel.

  The missing pixel detection unit 24 is configured by a separation circuit, a comparator, and the like. The pixel value based on the X-ray detection signal is spatially expanded for each detection element constituting the capacitor or the switching element 32 by the separation circuit, By comparing the developed pixel values, the pixel having the maximum value or the minimum value is detected as a defective pixel. The defective pixel detection unit 24 is not limited to the above-described configuration, and the defective pixel detection unit 24 is configured by a low-pass filter (LPF) and a subtracter, and a high-frequency component among the spatially expanded pixel signals. By passing only low-frequency components other than the steep pixel signal that is a low-pass filter and subtracting the low-frequency component and the entire signal with a subtractor to detect the steep pixels, that is, steep pixels, The pixel having the maximum value or the minimum value may be detected.

  In addition, the defective pixel is not limited to the pixel having the maximum value or the minimum value described above, a pixel having a constant value regardless of whether the X-ray is irradiated or not, or a constant value regardless of the X-ray incident dose. In addition, a pixel having a constant value up to an incident dose of X-rays, a pixel whose behavior is indefinite when exceeding a predetermined incident dose of X-rays, and a pixel that cannot detect X-rays are included. In order to detect these pixels that are not permanently defective pixels as defective pixels, the pixel value collection unit 21, the time dispersion calculation unit 22, and the histogram calculation unit 23 described above are provided in the preceding stage of the defective pixel detection unit 24. The pixel value collection unit 21, the time dispersion calculation unit 22, and the histogram calculation unit 23 will be described later with reference to the flowchart of FIG.

  The missing pixel interpolation unit 25 is configured by a median filter, for example, and detects a median pixel from a plurality of pixels by a median filter and replaces the missing pixel with the detected median pixel. Interpolate missing pixels.

  As shown in FIG. 3, the FPD 3 includes a glass substrate 31 and a thin film transistor TFT formed on the glass substrate 31. As shown in FIGS. 3 and 4, the thin film transistor TFT has a large number of switching elements 32 (for example, 1024 × 1024) formed in a vertical / horizontal two-dimensional matrix arrangement. The switching elements 32 are formed separately from each other. That is, the FPD 3 is also a two-dimensional array radiation detector.

  As shown in FIG. 3, an X-ray sensitive semiconductor 34 is stacked on the carrier collection electrode 33, and the carrier collection electrode 33 is connected to the source S of the switching element 32 as shown in FIGS. 3 and 4. Has been. A plurality of gate bus lines 36 are connected from the gate driver 35, and each gate bus line 36 is connected to the gate G of the switching element 32. On the other hand, as shown in FIG. 4, a multiplexer 37 that collects charge signals and outputs them to one is connected with a plurality of data bus lines 39 via amplifiers 38, and also shown in FIGS. Thus, each data bus line 39 is connected to the drain D of the switching element 32.

  With the bias voltage applied to the common electrode (not shown), the gate of the switching element 32 is turned on by applying the voltage of the gate bus line 36 (or 0 V), and the carrier collection electrode 33 is on the detection surface side. The charge signal (carrier) converted from the incident X-ray through the X-ray sensitive semiconductor 34 is read out to the data bus line 39 via the source S and drain D of the switching element 32. Until the switching element is turned on, the charge signal is temporarily accumulated and stored in a capacitor (not shown). The charge signals read to the respective data bus lines 39 are amplified by the amplifiers 38 and are collectively output as one charge signal by the multiplexer 37. The output charge signal is digitized by the A / D converter 8 and output as an X-ray detection signal.

  Next, a series of image processing in this embodiment apparatus will be described with reference to the flowchart of FIG. 5 and the histogram of FIG.

(Step S1) Collecting Pixel Values Sequentially with Time After the FPD 3 detects in the non-irradiated state without X-ray irradiation and digitizes it with the A / D converter 8, it sends it to the image processing unit 9 as pixels. In such a non-irradiation state, the FPD 3 detects X-rays for a predetermined time, and the pixel value collection unit 21 of the image processing unit 9 sequentially collects pixel values based on the detected X-rays with time. During this predetermined time, the pixel value collecting unit 21 collects pixel values for each pixel constituting the image. For example, when an image is composed of m (for example, vertical and horizontal 1024 × 1024) pixels, pixel values are sequentially collected for each m (1024 × 1024 minutes) pixels over time. Let the pixel value at a certain time be x _i (where i = 1, 2,..., N−1, n), and n be the number of frames obtained by dividing the frame period from a predetermined time.

(Step S <b _> 2) Calculation of temporal dispersion of pixel values Based on the temporal changes x ₁ , x ₂ ,..., X _n−1 , x _n of the pixel values collected by the pixel value collection unit 21, the time dispersion calculation unit 22 A variance (time variance) of the pixel value with respect to time is obtained. When the standard deviation is σ, the time dispersion is σ ² , and the time dispersion σ ² is expressed by the following equation (1).

(Step S3) Calculation of Histogram for Time Variance for Each Pixel Based on the time variance σ ² of the pixel values obtained by the time variance calculation unit 22 as in the above equation (1), the histogram calculation unit 23 A histogram relating to the time variance σ ² for each pixel is obtained as shown in FIG. Specifically, the standard deviation σ is obtained from the time variance σ ² , and further, the standard deviation in the spatial distribution of the standard deviation σ (standard deviation of the spatial distribution with respect to the time variance σ ² ) is obtained. When the standard deviation is ρ, the variance is ρ ² , and the variance ρ ² is expressed by the following equation (2). However, h = 1, 2,..., M−1, m.

  Actually, m in the above equation (2) does not have to be the total number of pixels constituting the above-described image, and may be the number of samples appropriately divided from the total number. The reason why m is the number of samples is to prevent the case where the obtained image has a large number of defects and the dispersion becomes larger than usual and the defect determination is difficult to perform.

As a histogram relating to the time variance σ ² for each pixel, the horizontal axis represents the standard deviation σ and the vertical axis represents the frequency (frequency related to m frequencies). Since this histogram can be regarded as having a substantially normal distribution, the standard deviation of normal pixels is concentrated around an average value ± several ρ.

(Step S4) Detection of Missing Pixel Pixels that do not appear constantly on the actual image but are regarded as missing have a standard deviation σ much larger or smaller than normal pixels. Therefore, a pixel that greatly deviates from a predetermined range of the standard deviation ρ (standard deviation ρ of the spatial distribution with respect to time dispersion σ ² ) in the spatial distribution of the standard deviation σ obtained by the above equation (2) is determined as an unstable defective pixel. To detect. In FIG. 6, the predetermined range is a standard deviation ρ × ± 6 times, that is, a range of ± 6ρ. A pixel having a time dispersion σ ² (in practice, standard deviation σ) outside the range of ± 6ρ can be regarded as being different from other surrounding pixels. Therefore, the defective pixel detection unit 24 detects such a pixel as a defective pixel.

  The reason why 6ρ is set as the predetermined range is based on a statistical viewpoint. In the range outside 6ρ, 3 to 4 data out of 1 million data statistically falls within the range, and in this embodiment, 3 to 4 pixels out of 1 million pixels are defective pixels. Is detected.

  Note that noise other than missing pixels is constantly superimposed on the actual image. Accordingly, the standard deviation σ usually has a certain value, and the range can be regarded as a range of ± 6ρ. Therefore, in the case of the standard deviation σ having a value smaller than the range of −6ρ, it can be considered that noise that should have been superimposed is canceled out by the defective pixel and becomes small. Therefore, detecting a pixel greatly deviating from the predetermined range by the histogram of FIG. 6 as an unstable defective pixel also separates noise from the defective pixel.

(Step S <b> 5) Missing Pixel Interpolation The missing pixel interpolation unit 25 performs the interpolation of the missing pixels detected by the missing pixel detection unit 24. The image processing unit 9 performs various processes other than steps S1 to S5 on the image including the defective pixel interpolated in this way. Then, a series of processing ends.

  According to the apparatus of the present embodiment configured as described above, the pixel value collection unit 21 sequentially collects pixel values based on X-rays detected in a non-irradiation state over time. Based on the time variation of the pixel value collected by the pixel value collecting unit 21, the time dispersion calculating unit 22 obtains a dispersion (time dispersion) of the pixel value with respect to time as a statistic of the pixel value temporal change. The time dispersion obtained in this way also serves as an index representing the history of the temporal change of the pixel value. Therefore, even for a pixel that is not permanently a defective pixel, the defective pixel detection unit 24 appropriately sets the defective pixel based on the time dispersion. Can be detected.

  Then, in order to interpolate the defective pixel detected by the defective pixel detection unit 24, a defective pixel interpolation unit 25 that performs interpolation of the defective pixel detected by the defective pixel detection unit 24 is provided. Based on the X-rays detected by the FPD (flat panel X-ray detector) 3, the defective pixel interpolation unit 25 performs image processing by interpolating the defective pixels, thereby imaging the subject.

  In the present embodiment, a histogram calculation unit 23 for obtaining a spatial distribution of time dispersion for each pixel obtained by the time dispersion calculation unit 22 (histogram relating to time dispersion for each pixel) is provided. A predetermined range is set from the obtained spatial distribution of time dispersion for each pixel (histogram relating to time dispersion for each pixel), and the defective pixel detection unit 22 detects pixels of time dispersion that are out of the predetermined range. Detect as. That is, by considering the spatial distribution for each pixel constituting the image, it is possible to detect a defective pixel as compared with surrounding pixels.

  In particular, when the spatial distribution of the time dispersion for each pixel is represented by a histogram relating to the time dispersion for each pixel, as described above, the histogram can be regarded as a substantially normal distribution. Pixels with time dispersion that deviate from the range of + several times the standard deviation of the spatial distribution with respect to time dispersion, or a range of ± several times, can be regarded as different from other surrounding pixels. Therefore, the defective pixel detection unit 24 can appropriately detect such a pixel as a defective pixel.

  The present invention is not limited to the above-described embodiment, and can be modified as follows.

  (1) In the above-described embodiment, the X-ray diagnostic apparatus as shown in FIG. 1 has been described as an example. However, the present invention is also applied to an X-ray diagnostic apparatus disposed on a C-type arm, for example. Also good. The present invention may also be applied to an X-ray CT apparatus.

  (2) In the above-described embodiment, the flat panel X-ray detector (FPD) 3 has been described as an example. However, X-ray detection configured by detection elements arranged in a two-dimensional matrix that partitions pixels. The present invention can be applied to any container.

  (3) In the above-described embodiments, the X-ray detector for detecting X-rays has been described as an example. However, in the present invention, a radioisotope (RI) is administered like an ECT (Emission Computed Tomography) apparatus. The radiation detector is not particularly limited as long as it is a radiation detector that detects radiation, as exemplified by a γ-ray detector that detects γ-rays emitted from a subject. Similarly, the present invention is not particularly limited as long as it is an apparatus that performs imaging by detecting radiation, as exemplified by the ECT apparatus described above.

  (4) In the above-described embodiment, the FPD 3 includes a radiation (in the embodiment, X-ray) sensitive semiconductor and directly converts the incident radiation into a charge signal by the radiation sensitive semiconductor. However, instead of the radiation-sensitive type, it is equipped with a light-sensitive semiconductor and a scintillator, and the incident radiation is converted into light by the scintillator, and the converted light is converted into a charge signal by the light-sensitive semiconductor. It may be an indirect conversion type detector.

(5) In the above-described embodiment, a pixel having a time dispersion σ ² (in practice, standard deviation σ) outside the range of ± 6ρ is detected as a defective pixel. However, as shown in FIG. A pixel having the standard deviation σ may be detected as a defective pixel. In addition, it is not limited to 6ρ, and may be 3ρ, 2ρ, or ρ from a statistical viewpoint. In the case of 3ρ, three pixels out of 1,000 pixels are detected as defective pixels. In the case of 2ρ, five pixels out of 100 pixels are detected as defective pixels. In the case of ρ, 32 pixels out of 100 pixels are detected as defective pixels.

  (6) In the above-described embodiment, pixel values based on X-rays detected in the non-irradiation state are sequentially collected over time, and the time change of the pixel value is determined based on the time change of the collected pixel value. Statistical values (time dispersion in the example) were calculated, but pixel values based on radiation (X-rays in the example) detected in the irradiation state of constant intensity (X-rays in the example) were sequentially collected over time. Then, a statistic (a time dispersion in the embodiment) of the pixel value over time may be obtained based on the collected time change of the pixel value.

  (7) In the above-described embodiment, the temporal dispersion of pixel values is described as an example of the statistical value of the temporal change of pixel values. However, the present invention is not limited to this. For example, the sum of the absolute values of the differences from the average of the pixel values may be adopted as the statistic of the pixel value over time.

It is a block diagram of the X-ray diagnostic apparatus which concerns on an Example. It is the block diagram which showed the specific structure of the image process part used for the X-ray diagnostic apparatus. It is the equivalent circuit of the flat panel type X-ray detector used for the X-ray diagnostic apparatus viewed from the side. 2 is an equivalent circuit of a flat panel X-ray detector in plan view. It is a flowchart which shows a series of image processing. It is the histogram showing the range of the defective pixel which concerns on an Example. It is a histogram showing the range of the defective pixel which concerns on a modification.

Explanation of symbols

3 ... Flat panel X-ray detector (FPD)
DESCRIPTION OF SYMBOLS 21 ... Pixel value collection part 22 ... Time dispersion | distribution calculation part 23 ... Histogram calculation part 24 ... Missing pixel detection part 25 ... Missing pixel interpolation part (sigma) ² ... Dispersion | distribution regarding the time of a pixel value (time dispersion | distribution)
M… Subject

Claims (2)

By providing radiation detection means for detecting radiation that has passed through the subject and defective pixel detection means for detecting defective pixels for pixel values based on the detected signals , and performing image processing based on the detected radiation, A radiation imaging apparatus for imaging a subject, a pixel value collecting unit for sequentially collecting pixel values based on signals detected in a non-irradiation state or a radiation irradiation state with a constant intensity, and a pixel value collection unit A statistic calculation means for obtaining a time variance , which is a variance related to the time of the pixel value, as a statistic of the time change of the pixel value based on the time change of the pixel value collected in step ( b), and the time variance of each pixel A spatial distribution calculation means for obtaining a spatial distribution, and when a predetermined range is set from the spatial distribution of the time dispersion for each pixel obtained by the spatial distribution calculation means, and deviates from the predetermined range The radiation imaging apparatus includes a variance of pixel said defective pixel detecting means and detecting a defective pixel. The radiation imaging apparatus according to claim 1, further comprising a defective pixel interpolation unit that performs interpolation of a defective pixel detected by the defective pixel detection unit, and based on the radiation detected by the radiation detection unit. A radiation imaging apparatus characterized in that imaging of a subject is performed by performing interpolation of defective pixels.

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