JP5188255B2 - Radiation imaging apparatus and image defect detection method - Google Patents

Description

  The present invention relates to a radiographic image capturing apparatus using a flat panel type radiation detector, and more particularly to a radiographic image capturing apparatus for detecting an image defect on a radiographic image generated by the radiographic image capturing apparatus and image defect correction. It is about the method.

Conventionally, radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.) transmitted through the subject (subject) is electrically used for taking medical diagnostic images and industrial nondestructive inspections. Radiation image detectors that detect as a simple signal are used.
As this radiation image detector, a flat panel type radiation detector that extracts radiation as an electrical image signal (so-called “Flat Panel Detector”, hereinafter also referred to as “FPD”), a radiation image is extracted as a visible image. There are X-ray image tubes.

  As a method of using FPD for a radiation image detector, for example, electron-hole pairs (eh pairs) emitted from a photoconductive film such as amorphous selenium by collecting radiation are collected and read out as a charge signal. There is a direct method for directly converting the signal into an electric signal.

In the radiographic image capturing apparatus using the FPD, defective pixels of the FPD are cited as one cause of the deterioration of the image quality of the radiographic image.
That is, the FPD pixels (radiation detection elements) are not only used to output a signal having an appropriate intensity (concentration) with respect to the amount of radiation that is always incident, but also due to, for example, defects during manufacturing. In some cases, there is a defective pixel that outputs a signal having a lower value or a higher value than the appropriate intensity with respect to the irradiation amount.

As a matter of course, a defective pixel cannot obtain an appropriate radiation image. Therefore, an image (image defect) corresponding to such a defective pixel causes a serious problem such as misdiagnosis.
Further, the defective pixels of the FPD tend to increase as the number of radiographic image capturing increases.
Therefore, in the radiographic image capturing apparatus using the FPD, the position of the defective pixel of the FPD is detected at a predetermined timing, and when a radiographic image is captured, peripheral pixels ( An image defect is corrected using the image data), an image defect correction is performed, and a radiographic image after the image defect correction is displayed or reproduced as a diagnostic image or the like.

  In addition, if there are too many defective pixels in the FPD, it is difficult to generate an accurate diagnostic image even if the image defect is corrected. Therefore, normally, the number of defective pixels in the FPD, the size, and / or the unit area. When the degree of congestion exceeds a predetermined threshold, an FPD is replaced or repaired by issuing an alarm (warning).

However, as described above, the defective pixels of the FPD tend to increase as the number of radiographic image captures increases, that is, as the radiation dose increases.
Therefore, when a radiographic image is captured in the FPD, image defects tend to increase particularly in a portion where the radiation reaches without being obstructed by the subject, that is, in a non-photographing portion (elementary portion) where the subject is not photographed. There is.
For example, when photographing a mammography image, since the shape of the object to be photographed is almost similar, there is a portion that is always a non-photographing portion in the FPD, and this portion may greatly increase image defects. is there.

  Therefore, if an image defect is detected for such a radiation image (radiation image data), an image defect in a non-imaging part that is not related to diagnosis is also detected, so the FPD corresponding to the detected image defect Even if the defective pixel is not a defective pixel at a location related to diagnosis, if the number, size, or density per unit area of the FPD exceeds a threshold, the FPD that can be continuously used is not used. The problem arises that repair or replacement is necessary.

  An object of the present invention is to prevent unnecessary repair or replacement of a radiation detector (FPD) that can issue an alarm (warning) unnecessarily and that can be used continuously, particularly a flat panel type FPD. An object of the present invention is to provide a radiographic imaging apparatus or an image defect detection method in which replacement or repair of an FPD is performed.

In order to achieve the above object, the present invention provides a radiographic imaging apparatus that captures a radiographic image of a subject using a radiation detector, and each time a radiographing is performed, for each pixel of the radiographic image captured. A history data generation unit that records radiation irradiation history and generates radiation irradiation history data, and the radiation detector after or without irradiating the radiation detector without the subject . from images defect detection image data generated using an image data read from by using the radiation irradiation target history data, it detects an image data of the non-imaging region where the object is not always captured, the image generating image data of the imaging area except the image data of the detected non-shooting regions from the image defect detection image data from the image data of the generated imaging area, the image missing There is provided a radiation image capturing apparatus characterized by having an image defect detecting section for detecting a.

  In the present invention, the history data generation unit initializes the radiation exposure history data, and each time imaging is performed, data of each pixel of the captured radiographic image is equal to or greater than a first threshold value. In some cases, the first predetermined value is subtracted from the data of the corresponding pixel of the radiation exposure history data, and when the data of each pixel of the captured radiographic image is less than the first threshold, Preferably, the radiation exposure history data is updated by adding a second predetermined value to the data of the corresponding pixel of the radiation exposure history data.

  In the present invention, it is preferable that the history data generation unit is configured to change the first and second predetermined values.

In the present invention, the image defect detecting section, data of each pixel of the radiation to be irradiated history data is equal to or less than the second threshold value, that pixel is positioned in the non-shooting region And when the pixel exceeds the second threshold, it is identified that the pixel is not located in the non-photographing region , and using these identification results, the image defect detection image data It is preferable to detect image data in a non-imaging area .

In the present invention, it is preferable that the image defect detection unit records the detected image defect information in defect recording data for recording the image defect information of the radiation image .

In the present invention, further includes an alarm generator for generating a warning for notifying the exchange timing of the radiation detector, the image defect detecting unit stores the history of the image defects the detection, the from the history, the number of defective pixels of the radiation detector, the size, and to predict the increase in density per unit area, the number of defective pixels of the radiation detector, the size, and, per unit area density Of these, when at least one predicted value exceeds a predetermined threshold value, it is preferable to instruct the alarm generation unit to generate a warning.

  In the present invention, the image defect detection unit may detect the detection when the width of the detected image defect is equal to or smaller than a predetermined threshold and the length is equal to or larger than a predetermined threshold. It is preferable to identify the image defect as a line defect.

In the present invention, the image defect detector is preferably one that identified as the radiation detector of the read line line defect having a split Go more defective pixels previously defined in the defect recording data.

  In the present invention, the image defect detection unit may be configured such that, among the pixels of the radiation detector corresponding to the positions on both sides of the line defect, both pixels sandwiching the line defect are defective pixels. It is preferable that pixels located between these defective pixels are also identified as defective pixels.

  In the present invention, the radiation detector is preferably a flat panel type radiation detector.

In order to achieve the above object, the present invention records a radiation irradiation history for each pixel of the captured radiographic image every time a radiographic image of the subject is captured using a radiation detector. The radiation irradiation history data is generated , and the image generated using the image data read from the radiation detector after irradiating the radiation detector with or without the subject being irradiated. from the defect detection image data, by using the radiation irradiation target history data, detects an image data of the non-imaging region where the object is not always captured, the image of the non-imaging area, which is the detected from the image defect detection image data data to generate image data of the imaging area excluding the, from the image data of the generated imaging area, to provide an image defect detection method characterized by detecting an image defect Than is.

  In the present invention, the radiation detector is preferably a flat panel type radiation detector.

  According to the present invention, in a radiation detector, particularly a flat panel radiation detector (FPD), a defective pixel in a part used for diagnosis is detected without detecting a defective pixel in a part that does not affect the diagnosis. As a result, when determining the number, size, and density of defective pixels in the detected FPD, it is almost impossible to record defective pixels in a portion that does not affect the diagnosis. Unnecessary replacement or repair of the FPD that can be done is rarely performed.

  Hereinafter, a radiographic imaging apparatus of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 is a block diagram of an embodiment showing a configuration of a radiographic image capturing apparatus of the present invention. A radiographic image capturing apparatus (hereinafter also referred to as an image capturing apparatus) 10 shown in the figure irradiates a subject (subject) H with radiation, detects the radiation transmitted through the subject H, and generates an electrical signal corresponding to image data. Based on the converted electrical signal, a radiographic image obtained by imaging the subject H is generated.
The imaging device 10 includes an imaging unit 12, an imaging data processing unit 14, an image processing unit 16, an output unit 18, an alarm generation unit 20, and a control unit 22.

The imaging unit 12 is a part that shoots the subject H by irradiating the subject H with radiation and detecting the radiation transmitted through the subject H. The imaging unit 12 outputs radiographic image data (analog data) obtained by imaging the subject H.
Details of the photographing unit 12 will be described later.

The imaging data processing unit 14 is a part that performs data processing such as A / D (analog / digital) conversion on the radiation image data supplied from the imaging unit 12. The radiographic image data (digital data) after the data processing is output from the imaging data processing unit 14.
Details of the imaging data processing unit 14 will be described later.

The image processing unit 16 is a part that performs image processing including the image defect correction according to the image defect detection method of the present invention on the data of the radiographic image after the data processing supplied from the imaging data processing unit 14.
The image processing unit 16 is configured by a program (software) operating on a computer, dedicated hardware, or a combination of both.
The image processing unit 16 outputs the radiation image data P1 after image processing and a signal for operating the alarm generation unit 20 (hereinafter referred to as an alarm generation instruction signal).
Details of the image processing unit 16 will be described later.

The output unit 18 is a part that outputs the radiation image data P <b> 1 after image processing supplied from the image processing unit 16.
The output unit 18 is, for example, a monitor that displays a radiation image on a screen, a printer that prints out a radiation image, a storage device that stores radiation image data, and the like.

  The alarm generation unit 20 is a part that notifies the replacement timing of a flat panel type radiation detector, which will be described in detail later, based on the alarm generation instruction signal supplied from the image processing unit 16, and as an example, A display panel or the like for informing the replacement time of the flat panel type radiation detector is used.

The control unit 22 is a part that controls the operation of the imaging apparatus 10.
For example, the control unit 22 controls the acquisition of the image data of the imaging data processing unit 14, and further controls the image processing of the image processing unit 16 and the generation of the radiation image data P1 after the image processing.

  Next, the photographing unit 12 will be described.

  The imaging unit 12 includes a radiation source 26, an imaging table 28, and imaging means 32.

The imaging unit 32 includes a flat panel radiation detector 30 (hereinafter also referred to as “FPD 30”), and captures a radiation image with the FPD 30.
The imaging apparatus 10 receives the radiation irradiated by the radiation source 26 and transmitted through the subject H by the light receiving surface of the FPD 30 and photoelectrically converts the radiation, as in a normal radiographic imaging apparatus. A radiographic image of H is taken.

The FPD 30 is a normal FPD used for a radiographic imaging device.
The FPD 30 uses a photoconductive film such as amorphous selenium and a TFT (Thin Film Transistor), etc., collects electron-hole pairs (eh pairs) emitted from the photoconductive film upon incidence of radiation, and uses the TFT. An example is a so-called direct FPD that is read out as an electrical signal.

In addition to the FPD 30, the imaging unit 32 may include various members included in a known radiographic imaging apparatus, such as a grid for shielding scattered radiation incident on the FPD 30, and a grid moving unit.
An output signal (image data) of a radiographic image captured by the imaging unit 32 (FPD 30) is supplied to the imaging data processing unit 14.

  Although not shown, the radiation source 26 and the imaging means 32 can reciprocate along the longitudinal direction (left and right direction in FIG. 1) of the imaging table 28 for the case of long imaging, for example. It is configured as follows. On the other hand, you may comprise the imaging stand 28 so that a movement is possible.

  Next, the photographing data processing unit 14 will be described.

  The imaging data processing unit 14 includes an image data acquisition unit 34 and an image data processing unit 36.

The image data acquisition unit 34 acquires the image data read from the FPD 30 and supplies this image data to the image data processing unit 36.
In the present embodiment, the image data acquisition unit 34 includes image data (hereinafter referred to as “image data”) read out from the FPD 30 after the radiation source 26 uniformly irradiates (explodes) radiation to the FPD 30 without passing through the subject H. (Also referred to as explosion image data G2) and image data read from the FPD 30 after the radiation source 26 irradiates the subject H (hereinafter also referred to as subject image data G3). Data G2 and G3 are supplied to the image data processing means 36.

The image data processing unit 36 performs data processing such as A / D (analog / digital) conversion on the image data G2 and G3 supplied from the image data acquisition unit 34, and the image data (digital data) after the data processing is performed. ) To the image processing unit 16.
In the present embodiment, the explosion image data G2 after data processing is referred to as processed explosion data J2, and the subject image data G3 after data processing is referred to as processed subject data J3.

  The image processing unit 16 will be described in detail.

FIG. 2 is a block diagram showing the configuration of the image processing unit 16 shown in FIG.
As shown in FIG. 2, the image processing unit 16 includes a data acquisition unit 38, a data generation unit 39, a history data generation unit 61, an image defect detection unit 62, a correction data generation unit 42, and an image correction unit 44. It consists of.

  The data acquisition unit 38 acquires the processed explosion data J2 and the processed subject data J3 supplied from the imaging data processing unit 14, and supplies the processed explosion data J2 to the data generation unit 39. The processed subject data J3 is supplied to the image correction means 44 and the history data creation means 61.

  The data generation means 39 creates image data for detecting image defects on the radiation image (hereinafter also referred to as image defect detection image data Q1) using the processed explosion data J2, and the image defect detection means 62. To supply.

The generation method of the image defect detection image data Q1 is not particularly limited. As an example, the processed explosion data J2 is averaged, and the processed explosion data J2 subjected to the averaging process is processed. And a method of subtracting from the processed explosion data J2.
The averaging process at this time is also not particularly limited, but a median filter process, a moving average process, and the like are preferably exemplified.

The history data creation means 61 records radiation exposure history for each pixel of the FPD 30 corresponding to the processed subject data J3, and generates radiation exposure history data (hereinafter also simply referred to as history data T1). And supplied to the image defect detection means 62.
The history data creating means 61 preferably generates radiation irradiation history data T1 after confirming that the processed subject data J3 is not image data or test image data narrowed down by the irradiation field stop. It is also a thing.

  Further, in the present embodiment, the history data creating means 61, after initializing the history data T1, that is, after setting the data corresponding to all FPD pixels to 0 in the history data T1, captures a radiographic image. The history data T1 is also updated every time.

  The method for updating the history data T1 is not particularly limited, and examples thereof include the following methods.

  First, the processed subject data J3 (data of the captured radiographic image) is set for each corresponding FPD pixel, for example, with a threshold value, and a non-imaging area (elementary image) in which the subject on the radiographic image is not captured. It is identified whether the object is located in the omission area) or in the imaging area where the subject on the radiographic image is taken.

Next, a first predetermined value is subtracted from the history data T1 corresponding to the processed subject data J3 identified as being located in the non-imaging area.
On the other hand, the second predetermined value is added to the history data corresponding to the processed subject data J3 identified as being located in the imaging region.

For example, if the first predetermined value is 1 and the second predetermined value is 1000, the processed test identified as being located in the imaging area in the history data T1 by the first update. Thereafter, the history data T1 corresponding to the patient data J3 must correspond to the processed subject data J3 identified as being located in the imaging region at least once by updating the history data T1 1000 times. In other words, it is 0 when corresponding to the processed subject data J3 identified as being located in the non-imaging area for 1000 consecutive times.
The first and second predetermined values are not particularly limited, but both can be changed.

  The image defect detection means 62 uses the history data T1 to detect non-photographing area data (hereinafter also referred to as non-photographing area image data) where the subject is not always photographed from the image defect detection image data Q1, and then Image data of an area (imaging area) excluding the non-imaging area from the image defect detection image (hereinafter also referred to as imaging area image data) is generated, and an image defect is detected from the imaging area image data.

  Here, the image defect detection method is not particularly limited, and all the image defect detection methods performed by various radiographic imaging apparatuses can be used. For example, when image irradiation is performed, the image defect detection method is set. And a method of detecting a pixel that outputs a signal having a value lower than or higher than the threshold value.

  The method for detecting non-photographing region image data is not particularly limited in the present invention, but when a threshold is set and the history data T1 corresponding to each pixel of the FPD is equal to or lower than the threshold, If the FPD pixel corresponding to the history data T1 is located in the non-photographing area, and the history data T1 corresponding to each pixel of the FPD exceeds the threshold, the FPD corresponding to the history data T1 A method is preferred in which the pixel is not located in the non-photographing area, that is, is located in the photographing area, and this result is used to detect the non-photographing area image data from the image defect detection image data Q1. .

  Here, for example, when the threshold value is set to 0, if the history data T1 is 0 or less, the FPD pixel corresponding to the history data T1 is located in the non-photographing area, while the FPD If the history data T1 corresponding to each of the pixels exceeds the threshold value, it is identified that the pixel of the FPD corresponding to the history data T1 is located in the imaging region, and the data of the history data T1 is Distinguishing between a shooting area and a shooting area.

  As described above, the image defect detection means 62 identifies the data corresponding to each pixel of the FPD of the history data T1 into the non-photographing region and the photographing region, and uses the result to detect the image defect. By detecting non-photographing region image data from the image data Q1, and further detecting an image defect from data of a region obtained by excluding non-photographing region data from the image defect detection image, that is, photographing region image data, An image defect is not detected for a portion that is always a non-photographing region.

  Further, in the present embodiment, the image defect detection means 62 detects the information of the detected image defect (defective pixel) in the defect recording data M1 for recording the information (number, position, density, etc.) of the image defect of the radiation image. Is recorded and supplied to the correction data creating means 42.

  Further, in the present embodiment, the image defect detection means 62 records the detected image defect history in the defect history data for recording the image defect history based on the defect recording data, and then the defect history data. If the number of defective pixels of the FPD 30 is predicted and the number of defective pixels of the FPD 30 is predicted to exceed a prescribed value that may affect the diagnosis within a predetermined period, The alarm generation unit 20 is also sent with an alarm generation instruction signal.

Conventionally, when the number of defective pixels in the FPD 30 exceeds a specified value at which the influence on the diagnosis is concerned, an alarm is issued. Therefore, the FPD 30 must be replaced immediately regardless of the situation of diagnosis or the like. won.
However, by predicting an increase in image defects (defective pixels) of the FPD 30 as described above, there is a time lapse before the FPD 30 is replaced, and the FPD 30 can be used when the photographing apparatus 10 is not used. Can be repaired or replaced.
The method for predicting an increase in image defects (defective pixels) is not particularly limited, but using an appropriate function such as linear approximation or exponential approximation, and taking into account the characteristics of the FPD 30 as necessary. It is preferred to do so.

  The correction data creating means 42 creates image defect correction data N1 used for correcting image defects of the radiation image data (processed subject image data J3) using the defect recording data M1 and supplies the image defect correction data N1 to the image correcting means 44. It is a part to do.

The image correction unit 44 is a part that corrects the image defect of the processed subject image data J3 supplied from the data acquisition unit 38 based on the image defect correction data N1 supplied from the correction data creation unit 42.
For example, the image correction unit 44 specifies the position of the defective pixel that needs correction processing based on the acquired image defect correction data N1, obtains an average value of two normal pixels around the specified defective pixel, Image defect correction is performed by using this as image data of a defect image.

Here, the method of correcting the defective pixel is not particularly limited, and other than the method of using the average value of a plurality of neighboring pixels on both sides and the periphery as the data of the defective pixel (the pixel), the pixel of the predetermined area around the defective pixel Image defect correction methods used in various types of radiographic imaging apparatuses, such as a method of generating defective pixel data from a change tendency, can be used.
For example, the defective pixel may be corrected by a weighted average value calculated using three or more normal pixels around the defective pixel and the distance between each normal pixel and the defective pixel.

  The radiographic imaging apparatus 10 of the present invention having the above configuration can detect a defective pixel in a part used for diagnosis without detecting a defective pixel in a part that does not affect the diagnosis in the FPD. When recording the history of the defective pixels of the detected FPD, it is almost impossible to record the defective pixels in the portion that does not affect the diagnosis, so that unnecessary replacement or repair of the FPD that can be continuously used is rarely performed. No longer done.

  The operation of the photographing apparatus 10 of the present invention having the above configuration will be described.

In the imaging apparatus 10 of the present invention, the explosion image data G2 and the subject image data G3 are generated in the FPD 30 of the imaging unit 12.
Next, the imaging data processing unit 14 acquires the image data G2 and G3 and converts them into digital data (processed explosive image data J2 and processed subject image data J3), respectively, and the image processing unit 16 is supplied.
Further, the data acquisition unit 38 in the image processing unit 16 acquires the digital data J2 and J3, supplies the processed explosive image data J2 to the data generation unit 39, and performs image correction on the processed subject image data J3. The data is supplied to the means 44 and the history data creation means 61.

Next, the data generation means 39 generates image defect detection image data Q1 using the processed explosion data J2, and supplies the image defect detection image data Q1 to the image defect detection means 62.
On the other hand, the history data creating means 61 generates history data T 1 and supplies it to the image defect detecting means 62.

In the image defect detection means 62, the history data T1 is used to detect a non-photographing area from the image defect detection image data Q1, and an image defect is detected from the image area data.
Next, information (number, position, density, etc.) of the detected image defect is recorded in the defect recording data M1, and supplied from the image defect detecting means 62 to the correction data creating means 42.
Further, the image defect detection means 62 reflects the history of the detected image defect (defective pixel) in the defect history data based on the defect recording data M1.

In the correction data creation means 42, image defect correction data N 1 is created using the defect recording data M 1 and supplied to the image correction means 44.
Next, the image correction means 44 corrects the image defect of the processed subject image data J3 based on the image defect correction data N1, and creates the radiation image data P1 after the image processing (after the image defect correction), This is supplied to the output unit 18.
Finally, the output unit 18 outputs the radiation image data after the image processing supplied from the image correction unit 44 (image processing unit 16).

Next, an example of processing of the image defect detection unit 62 will be described with reference to FIGS. 3 and 4.
3 and 4 are flowcharts showing an example of processing of the image defect detection means 62. FIG.

First, image defect detection image data Q1 and history data T1 are acquired from the data generation means 39 (S80).
Next, a non-photographing area is detected from the image defect detection image data Q1 (S82).
Shooting area image data is generated by removing the non-shooting area from the image defect detection image (S84).

  Next, a black defect or a white defect is detected from the shooting area image data (S86).

  The white defect or black defect detection method is not particularly limited. For example, a black defect detection threshold table and a white defect detection threshold table corresponding to the size of the image defect (range of pixels having pixel defects). And a method of detecting white defects and black defects.

  Usually, when the size of a defect is small (when the range of pixels having a defect is small), it is difficult to visually recognize the image defect as an image defect on a radiation image unless the density of the image defect is very high. On the other hand, when the size of the image defect is large (when the range of pixels having a defect is wide), the image defect is visually recognized as an image defect on the radiation image even if the density of the image defect is low. It becomes easy. For this reason, in the present embodiment, different threshold tables are used depending on the size of image defects (range of pixels having defects).

In addition, the ease of visually recognizing the image defect differs depending on whether the defect is black or white.
Therefore, in this embodiment, different threshold tables are used for black defects and white defects in order to accurately detect white defects and black defects.

  That is, in the present embodiment, in order to accurately and effectively perform the subsequent image defect correction, a white defect and a black defect having various sizes are displayed as threshold values for black defect detection according to the size of the image defect. In addition, a threshold value table for detecting white defects is prepared, and a detection method using these is used.

  The detected image defect is identified as an image defect caused by the defective pixel of the FPD 30, and defect recording data M1 to be recorded is generated and recorded (S88).

  Next, an image defect having a width equal to or smaller than a predetermined threshold (predetermined value) and a length equal to or larger than a predetermined threshold (predetermined value) is detected from the defect recording data M1 (S90).

  Here, the line defect is a defect in which defective pixels are continuous in a linear shape (for example, a width of 2 pixels or less and a length of 21 pixels or more).

  When an image defect whose width is equal to or smaller than a predetermined threshold and whose length is equal to or larger than a predetermined threshold is detected, the image defect in the corresponding part is identified as a line defect, and line defect data prepared in advance In addition, the fact that the line defect has been identified is recorded as defect record data M1 (S92).

  As described above, by identifying an image defect that satisfies the above conditions as a line defect, an unstable point defect that has been recognized as a dotted line can be recognized as a line defect. Thereby, an appropriate image defect correction can be performed in a later process.

  Whether or not a line defect is detected, the image defect detection means 62 uses the line defect data prepared in advance to examine all the pixels located on both sides of the line defect in the defect recording data M1 to detect the line defect. It is checked whether or not both the sandwiched pixels are defective pixels (S94).

  If there is a corresponding pixel, the pixel is recognized as a defective pixel of the FPD 30 and recorded in the defect recording data M1 (S96).

  Whether or not there is such a pixel, the line defect data prepared in advance may be set in advance at the position of the tip of the line defect that has been broken in the FPD 30 if there is a line defect that has been broken in the middle. Assuming that there is a point defect of the specified size, it is recorded in the defect recording data M1 (S98).

  Next, the image defect detection means 62 detects pixels in which three or more of the upper, lower, left, and right pixels are defective pixels in the defect recording data M1 (S100).

  When three or more pixels are detected as defective pixels among the upper, lower, left, and right pixels, the pixel may be a defective pixel that has not been detected by noise such as random noise in the image defect detection means 62. Is very high, it is identified as a point defect of the FPD 30 and recorded in the defect recording data M1 (S102).

  Next, the history of the image defect (defective pixel) recorded in the defect recording data M1 is reflected in the defect history data for recording the history of the image defect (defective pixel) (S107).

Next, based on the defect history data, it is confirmed whether the size of the image defect (defective pixel), the density per unit area, and the number satisfy the specifications of the FPD 30 (specified values that can be used for diagnosis). (S108).
If the specification is not satisfied, first, an alarm generation instruction signal is sent to the alarm generation unit 20 (S110).

  Whether or not the specification of the FPD 30 is satisfied or not, the defect recording data M1 is supplied from the image defect detecting means 62 to the correction data creating means 42 (S112).

  In the above-described embodiment, the line defect is identified by defining the width and length of the image defect. However, the present invention is not limited to this, and the defect recording data M1 has a ratio equal to or higher than a predetermined ratio. For example, a readout line of the FPD 30 having about 10% or more defective pixels may be identified as a line defect.

  In the above embodiment, the image correction unit 44 performs only the image defect correction process. However, the present invention is not limited to this, and the image processing performed by the image correction unit 44 is not limited to the image defect correction process. For example, offset correction (dark correction), gain correction (shading correction), gradation correction, density correction, and monitor display or print output performed according to calibration together with image defect correction Image processing that is performed in various types of radiographic imaging devices, such as data conversion that converts image data into this data, may be performed.

  As described above, by identifying an image defect (line) that satisfies the above conditions as a line defect, an unstable line defect that has been recognized as a dotted line can be recognized as a line defect. Thereby, an appropriate image defect correction can be performed in a later process.

The present invention is basically as described above.
Although the radiographic imaging apparatus of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various improvements and modifications may be made without departing from the spirit of the present invention. It is.

It is a block diagram of one embodiment showing composition of a radiographic imaging device of the present invention. FIG. 2 is a block diagram illustrating a configuration of an image processing unit illustrated in FIG. 1. It is a flowchart of an example of the process implemented by the image defect detection means of this invention. FIG. 4 is a flowchart showing a continuation of FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Radiographic imaging device 12 Imaging part 14 Imaging | photography data processing part 16 Image processing part 18 Output part 20 Alarm generation part 22 Control part 26 Radiation source 28 Imaging stand 30 FPD
32 Imaging means 34 Image data acquisition means 36 Image data processing means 38 Data acquisition means 39 Data generation means 42 Correction data creation means 44 Image correction means 62 Image defect detection means 61 History data creation means G2 Explosive image data G3 Subject image Data J2 Processed image data J3 Processed subject image data M1 Defect record data N1 Image correction data P1 Radiation image data Q1 Image defect detection image data

Claims (12)

A radiographic imaging device that captures a radiographic image of a subject using a radiation detector,
A history data generation unit that records radiation irradiation history and generates radiation irradiation history data for each pixel of the captured radiographic image every time imaging is performed,
From the image defect detection image data generated by using the image data read from the radiation detector after irradiating the radiation detector with or without irradiating the radiation detector. Using the irradiation history data, the image data of the non-photographing area where the subject is not always photographed is detected, and the image data of the photographing area excluding the detected image data of the non-photographing area from the image defect detection image data. A radiographic imaging apparatus comprising: an image defect detection unit that generates and detects an image defect from image data of the generated imaging region.   The history data generating unit initializes the radiation exposure history data, and each time imaging is performed, the data of each pixel of the captured radiographic image is greater than or equal to a first threshold value. A first predetermined value is subtracted from the corresponding pixel data of the irradiation history data, and the radiation irradiation history data when the data of each pixel of the captured radiation image is less than the first threshold value. The radiographic image capturing apparatus according to claim 1, wherein the radiation irradiation history data is updated by adding a second predetermined value to the data of the corresponding pixel.   The radiographic image capturing apparatus according to claim 2, wherein the history data generation unit is configured to be able to change the first and second predetermined values.   The image defect detection unit identifies that the pixel is located in the non-imaging region when the data of each pixel of the radiation irradiation history data is equal to or less than a second threshold, and the second The pixel is not located in the non-photographing area, and using these identification results, the image data for the non-imaging area is determined from the image defect detection image data. The radiographic imaging device according to any one of claims 1 to 3, wherein the radiographic image capturing device according to any one of claims 1-3 is detected.   The radiographic imaging according to claim 1, wherein the image defect detection unit records information on the detected image defect in defect recording data for recording image defect information on the radiographic image. apparatus. Furthermore, it has an alarm generating unit for generating a warning notifying the replacement timing of the radiation detector,
The image defect detection unit stores a history of the detected image defects, and predicts an increase in the number of defective pixels of the radiation detector, a size, and a density per unit area from the history, and the radiation Instructs the alarm generation unit to generate a warning when at least one predicted value out of the number, size, and density per unit area of the detector exceeds a predetermined threshold. The radiographic imaging device according to any one of claims 1 to 5.   The image defect detection unit determines that the detected image defect is a line defect when the width of the detected image defect is equal to or smaller than a predetermined threshold value and the length is equal to or larger than a predetermined threshold value. The radiographic image capturing apparatus according to claim 1, wherein the radiographic image capturing apparatus is for identification. The radiographic image capturing apparatus according to claim 5, wherein the image defect detection unit identifies a readout line of the radiation detector having defective pixels in a predetermined ratio or more in the defect recording data as a line defect.   The image defect detection unit, when pixels on both sides sandwiching the line defect among the pixels of the radiation detector corresponding to the positions on both sides of the line defect are both defective pixels, The radiographic image capturing apparatus according to claim 7, wherein pixels located between them are also identified as defective pixels.   The radiation image capturing apparatus according to claim 1, wherein the radiation detector is a flat panel type radiation detector. Each time a radiographic image of a subject is captured using a radiation detector, for each pixel of the captured radiographic image, a radiation exposure history is recorded to generate radiation exposure history data,
After irradiating the radiation detector with or without the subject, or without irradiating the radiation detector, image radiation detection image data generated from image data read from the radiation detector is used to detect the radiation exposure. Using the irradiation history data, the image data of the non-photographing area where the subject is not always photographed is detected, and the image data of the photographing area excluding the detected image data of the non-photographing area from the image defect detection image data. An image defect detection method comprising: generating and detecting an image defect from image data of the generated imaging region.   The image defect detection method according to claim 11, wherein the radiation detector is a flat panel type radiation detector.

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