JP2013079927A - Radiation image photographing device and radiation image photographic method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the deviation of the pixel position (centroid position of a pixel group) after addition in the horizontal, vertical, and oblique directions when using the pixel value of each pixel in each pixel group by adding them for each pixel group prepared by combining a plurality of neighboring pixels and to secure resolution in each direction.SOLUTION: For each pixel group prepared by combining a plurality of neighboring pixels of a radiation detector in which a plurality of hexagonal pixels are disposed in a honeycomb pattern, the pixel value of each pixel in each pixel group is added, and interpolation processing is performed on image data the pixel value of which is the total value of each pixel of the pixel group so that the plurality of pixels mean image data representing an image in which a plurality of pixels are disposed in a rectangular grid pattern. The combination of each pixel of a pixel group is determined in such a manner that when a plurality of hexagonal areas, each of which includes one centroid and is formed by connecting six centroids around the centroid, are formed adjacently using the centroid of each area surrounded by the borders of pixel groups, the plurality of hexagonal areas thus formed are disposed in a honeycomb pattern.

Description

  The present invention relates to a radiation image capturing apparatus and a radiation image capturing method for capturing a radiation image.

  2. Description of the Related Art In recent years, a radiographic imaging apparatus using a radiation detector such as an FPD (flat panel detector) that can arrange an X-ray sensitive layer on a TFT (Thin film transistor) active matrix substrate and convert X-ray information directly into digital data. It has been put into practical use. Compared with a conventional film screen or the like, this FPD has an advantage that an image can be confirmed immediately and a moving image can also be confirmed, and is rapidly spreading. Various types of radiation detectors have been proposed. For example, a direct conversion method in which radiation is directly converted into charges in a semiconductor layer and stored, or radiation is once converted into CsI: Tl, GOS (Gd2O2S: Tb). ) And the like, and an indirect conversion method in which the converted light is converted into charges in a semiconductor layer and accumulated.

  In the radiation detector, for example, a plurality of scanning wirings and a plurality of signal wirings are arranged so as to intersect with each other, and pixels are provided in a matrix corresponding to each intersection of the scanning wirings and the signal wirings. The plurality of scanning lines and the plurality of signal lines are connected to an external circuit (for example, an amplifier IC (Integrated Circuit) or a gate IC) in the peripheral portion of the radiation detector.

  In order to improve the resolution of the FPD, it is effective to reduce the pixel size of the radiation detector. In particular, in a direct conversion type radiation detector using Se or the like, since the pixel size contributes to the improvement of the resolution almost directly, various types of radiation detectors for improving the image quality by high definition have been proposed. For example, a product with a small pixel size has been proposed for an FPD for mammography that places importance on resolution.

  However, since the sensitivity is reduced simply by reducing the size, it has been proposed to use hexagonal pixels in the radiation detection apparatus in order to achieve both resolution and sensitivity improvement (see, for example, Patent Document 1). ). With rectangular pixels, the resolution in the diagonal direction is lower than in the horizontal and vertical directions, but by using hexagonal pixels, it is possible to ensure high resolution in each of the horizontal, vertical, and diagonal directions. it can.

JP 2003-255049 A

  However, even if hexagonal pixels are used, sufficient sensitivity may not be obtained if the radiation dose is small, and at high frame rates such as moving images, detection is not only a problem of sensitivity. In addition, there is a demand to perform image processing of a radiographic image early and output without delay, and therefore, a method (binning) in which pixel values detected from a plurality of pixels are added and used is required.

  However, depending on the addition method at the time of adding pixel values of a plurality of pixels, the pixel position after the addition (the center of gravity position when the plurality of pixels are a single pixel) is biased, and the shape symmetry is poor. Therefore, there is a possibility that a uniform resolution cannot be ensured in each of the horizontal, vertical, and diagonal directions. Even in the case of adding pixel values, it is necessary to devise so that the centroid positions are arranged without deviation in each direction.

  The present invention has been made in view of the above-described fact, and for each pixel group in which a plurality of adjacent pixels of a radiation image having hexagonal pixels arranged in a honeycomb shape are combined, each pixel in each pixel group When the pixel values are added and used, the bias of the pixel position after the addition (the center of gravity position of the pixel group) is suppressed in each of the horizontal direction, the vertical direction, and the diagonal direction, and the resolution is secured in each direction. It is an object of the present invention to provide a radiographic image capturing apparatus and a radiographic image capturing method capable of performing the same.

  In order to achieve the above object, a radiographic imaging apparatus according to claim 1 includes a radiation detector in which a plurality of hexagonal pixels of the same size for detecting radiation are arranged in a honeycomb shape, and the radiation detector For each pixel group in which a plurality of adjacent pixels are combined, an adding means for adding pixel values of each pixel in each pixel group, and a first value having a total value of pixel values of each pixel in the pixel group as a pixel value Pixel density conversion means for performing interpolation processing so that the image data becomes second image data representing an image in which a plurality of pixels are arranged in a square lattice pattern, and the addition means includes: Using the center of gravity of each region surrounded by the contour, adjacent hexagonal regions formed by connecting one center of gravity and connecting six centers of gravity existing around the center of gravity with lines. When a plurality is formed, the formed plurality As hexagonal areas of are arranged in a honeycomb shape, it is characterized in that defining the combination of the pixels of the pixel group.

  Thus, for each pixel group, adding means for adding the pixel values of each pixel in the pixel group, and the first image data having the total pixel value of each pixel in the pixel group as a pixel value, a plurality of pixels Each having a pixel density conversion for performing an interpolation process so as to be second image data representing an image arranged in a square lattice, and each pixel group is surrounded by a pixel group outline. When a plurality of hexagonal regions formed by connecting six centroids existing around the one centroid with lines are formed adjacent to each other using the centroid, Since the plurality of hexagonal regions formed are determined so as to be arranged in a honeycomb shape, the pixel position after addition (the barycentric position of the pixel group) in each of the horizontal direction, the vertical direction, and the diagonal direction is offset. Suppressed image detected with hexagonal pixels before addition Similarly, it is possible for each direction to secure the resolution and.

  As in the second aspect of the invention, the pixel density conversion unit first performs an interpolation process in the first image data in a direction in which the arrangement pitch of the center of gravity is short in the horizontal direction and the vertical direction, The interpolation process in the other direction may be performed later.

  If the interpolation process is performed from the shorter distance, the accuracy is higher than that from the opposite direction, and the conversion speed is also increased. Thereby, the pixel value detected by the hexagonal pixel can be fully utilized.

  Further, as in the invention described in claim 3, the hexagonal pixels may be formed to have a regular hexagonal shape.

  With such a shape, the position of the center of gravity of the regular hexagonal pixel 20 and the position of the center of gravity of the pixel group when the adding means adds together are equally spaced in the horizontal direction, the vertical direction, and the diagonal direction. The resolution can be ensured without bias in the direction.

  Further, as in the invention described in claim 4, the hexagonal pixels may be formed to have a flat hexagonal shape.

  Further, in the case of using the radiographic imaging apparatus as a mammography apparatus for imaging a breast of a subject as in the invention described in claim 5, the hexagonal pixel is defined as a depth from the chest wall side to the breast tip. You may make it flat so that the length of a direction may become shorter than the width | variety of the direction which cross | intersects this direction.

  According to a sixth aspect of the invention, in the hexagonal pixel, one of the three diagonal lines passing through the center of the pixel is made shorter than the other two diagonal lines, and the other These two diagonals may be flattened so as to have the same length.

  According to a seventh aspect of the present invention, the third image data composed of pixel values of the respective pixels of the radiation detector is used as a fourth image representing an image in which a plurality of pixels are arranged in a square lattice pattern. In accordance with the second pixel density converting means for performing interpolation processing so as to become data, the photographing mode for photographing a still image or a moving image, or the radiation dose, addition of the pixel value by the adding means is performed, and First control for controlling the pixel density conversion means to perform interpolation processing, and control for performing interpolation processing by the second pixel density conversion means without adding pixel values in the adding means. And a control means for performing any one of the second controls.

  Thereby, an appropriate interpolation process according to the case can be performed.

  As in the invention described in claim 8, further comprising setting means for setting a combination of a plurality of pixels constituting each of the pixel groups in accordance with a photographing mode for photographing a still image or a moving image or a radiation dose. It may be.

  Thereby, it is possible to set and add an appropriate pixel group according to the case.

  According to a ninth aspect of the present invention, in the case where a defective pixel is included in the pixel group, the adding unit calculates an average value of pixel values of normal pixels excluding the defective pixel in the pixel group. May be added as the pixel value of the defective pixel.

  As a result, even if a defective pixel is included in the pixel group, an image with a small area that is recognized as abnormal in image quality can be obtained.

  A combination of a plurality of pixels constituting each pixel group is arranged such that two adjacent sides of each pixel are adjacent to one side of each of the other two pixels. A combination of the three pixels, the three pixels, and one pixel arranged such that each of the two adjacent sides is adjacent to one side of each of the two pixels of the three pixels A combination of four pixels, and a combination of seven pixels including one central pixel and six pixels located around the central pixel, each side of the peripheral pixel being the center Any of the combinations of seven pixels arranged so as to be adjacent to any one side of these pixels may be used.

  As in the invention described in claim 11, it may further comprise a radiation source for irradiating radiation and an image output device for outputting an image based on the second image data.

  The radiographic imaging method of the invention of claim 12 is provided for each pixel group in which a plurality of adjacent pixels of a radiation detector in which a plurality of hexagonal pixels of the same size for detecting radiation are arranged in a honeycomb shape are combined. An addition step of adding pixel values of each pixel in the pixel group, and first image data having a pixel value that is a sum of pixel values of each pixel of the pixel group, a plurality of pixels are arranged in a square lattice pattern A pixel density conversion step of performing an interpolation process so as to be second image data representing the obtained image, and in the addition step, one centroid of each region surrounded by the outline of the pixel group is used. A plurality of hexagonal shapes formed when a plurality of hexagonal regions are formed adjacent to each other and formed by connecting six centroids existing around the center of gravity with lines. Area is arranged in a honeycomb , It is characterized in that defining the combination of the pixels of the pixel group.

  Since the invention according to claim 12 also operates in the same manner as the invention according to claim 1, the bias of the pixel position after addition (the barycentric position of the pixel group) in each of the horizontal direction, the vertical direction, and the diagonal direction As in the case of the image detected by the hexagonal pixels before the addition, the resolution can be ensured for each direction.

  As in the invention described in claim 13, in the pixel density conversion step, interpolation processing in the direction in which the array pitch of the center of gravity of each region is short in the horizontal direction and the vertical direction in the first image data is first performed. The interpolation processing in the other direction may be performed later.

  As described above, according to the present invention, the pixel value of each pixel in each pixel group is calculated for each pixel group obtained by combining a plurality of adjacent pixels of a radiation image having hexagonal pixels arranged in a honeycomb shape. When added and used, it is possible to suppress the bias in the pixel position after addition (the barycentric position of the pixel group) in each of the horizontal direction, the vertical direction, and the diagonal direction, and to ensure the resolution in each direction. It has an excellent effect.

It is a block diagram which shows the structure of the radiography system which concerns on embodiment. It is a block diagram which shows the structure of the radiation detector which concerns on embodiment. It is a top view which shows the arrangement state of the pixel of the radiation detector which concerns on embodiment. It is sectional drawing which shows the structure of the radiation detector which concerns on embodiment. It is the schematic diagram which showed typically the content of the pixel density conversion process in case the binning which concerns on this Embodiment is not performed. It is a flowchart in the case of performing pixel density conversion after binning. It is a figure which shows the example of arrangement | positioning of the pixel group to bin. It is a figure which shows the gravity center position of the pixel group corresponding to FIG. It is the figure which showed typically the content of the pixel density conversion process performed after a binning. It is a figure which shows the other example of arrangement | positioning of the pixel group to bin. It is a figure which shows the gravity center position of the pixel group corresponding to FIG. It is a figure which shows the other example of arrangement | positioning of the pixel group to bin. It is a figure which shows the gravity center position of the pixel group corresponding to FIG. It is a flowchart of the setting process which sets a pixel group according to a radiation dose. It is a block diagram which shows the structure of the radiation detector which concerns on another form. It is a block diagram which shows the structure of the radiation detector which concerns on another form. It is a figure which shows the other example of arrangement | positioning of the pixel group to bin. It is a figure which shows the gravity center position of the pixel group corresponding to FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the following, a case where the present invention is applied to a direct-conversion radiation detector that directly converts radiation into electric charge will be described.

  FIG. 1 is a block diagram showing a configuration of a radiographic image capturing system 100 according to the present embodiment. The radiographic image capturing system 100 includes an image capturing device 41 that captures a radiographic image, an image processing device 50 that performs image processing on image data representing the captured radiographic image, and a subject image represented by the image data that has undergone image processing. And a display device 80 that performs display.

  The imaging apparatus 41 includes a radiation irradiation unit 24, a radiation detector 42 that detects a radiation image (see also FIG. 2), exposure conditions such as tube voltage, tube current, irradiation time, and other information, imaging conditions, and various types. Connected to an operation panel 44 through which operation information and various operation instructions are input, a photographing apparatus control unit 46 that controls the operation of the entire apparatus, a display 47 that displays operation menus and various information, and a network 56 such as a LAN. And a communication I / F unit 48 that transmits and receives various types of information to and from other devices connected to the network 56. The imaging device 41 according to the present embodiment is configured to be switchable between a moving image shooting mode for continuously capturing radiographic images (moving image shooting) and a still image shooting mode for performing still image shooting. It is possible to input from the operation panel 44 as one of the above. In the photographing apparatus 41, moving image photographing or still image photographing is performed according to the photographing mode input from the operation panel 44.

  The imaging device control unit 46 includes a CPU 46A, ROM 46B, RAM 46C, a nonvolatile storage unit 46D including an HDD, a flash memory, and the like, and includes a radiation irradiation unit 24, a radiation detector 42, an operation panel 44, a display 47, and a communication. It is connected to the I / F unit 48. The storage unit 46D stores a program executed by the CPU 46A. The storage unit 46D stores image data (digital data) representing a radiation image. For example, when the imaging device 41 according to the present embodiment is used for mammography, the radiation image data obtained by imaging the subject's breast is stored in the storage unit 46D.

  When radiation is irradiated from the radiation source 30 of the radiation irradiation unit 24 according to the exposure conditions, the radiation detector 42 detects the radiation and outputs image data indicating the radiation image to the imaging device control unit 46. The detailed configuration of the radiation detector 42 will be described later.

  The imaging device control unit 46 can communicate with the image processing device 50 via the communication I / F unit 48 and the network 56, and transmits / receives various information to / from the image processing device 50.

  A management server 57 is further connected to the network 56. The management server 57 includes a storage unit 57A. The imaging device control unit 46 can communicate with the management server 57 via the communication I / F unit 48 and the network 56.

  On the other hand, the image processing apparatus 50 is configured as a server computer, and includes a display 52 that displays an operation menu, various information, and the like, and a plurality of keys, and an operation input for inputting various information and operation instructions. Part 54.

  The image processing apparatus 50 also stores and holds a CPU 60 that controls the operation of the entire apparatus, a ROM 62 that stores various programs including a control program in advance, a RAM 64 that temporarily stores various data, and various data. Connected to the photographing apparatus 41 via the network 56, a display driver 68 that controls the display of various information on the display 52, an operation input detection unit 70 that detects an operation state of the operation input unit 54, and a network 56. A communication I / F unit 72 that transmits and receives various types of information to and from the device 41 and an image signal output unit 74 that outputs image data to the display device 80 via the display cable 58 are provided. The image processing device 50 acquires image data (digital data) representing the radiation image stored in the storage unit 46D from the imaging device 41 via the communication IF unit 72.

  The CPU 60, ROM 62, RAM 64, HDD 66, display driver 68, operation input detection unit 70, communication I / F unit 72, and image signal output unit 74 are connected to each other via a system bus BUS. Therefore, the CPU 60 can access the ROM 62, RAM 64, and HDD 66. Further, the CPU 60 controls the display of various information on the display 52 via the display driver 68, controls the transmission / reception of various information with the imaging device 41 via the communication I / F unit 72, and the image signal output unit 74. The image displayed on the display unit 80A of the display device 80 can be controlled. Furthermore, the CPU 60 can grasp the operation state of the user with respect to the operation input unit 54 via the operation input detection unit 70.

  In the image processing device 50, binning and pixel density conversion, which will be described later, are performed on the image data representing the radiation image detected by the radiation detector 42. Programs for performing binning and pixel density conversion are stored in the ROM 62 and the HDD 66. The image data output to the display device 80 is image data after pixel density conversion.

  FIG. 2 shows an electrical configuration of the radiation detector 42 according to the present exemplary embodiment.

  The radiation detector 42 is provided with a rectangular detection region 40 and detects the radiation applied to the detection region 40. In this detection area 40, a plurality of hexagonal pixels 20 of the same size are arranged. This hexagonal pixel may be a regular hexagon or a flat hexagon. The hexagonal pixel includes a substantially hexagonal pixel in which each hexagonal corner is chamfered.

  In the present embodiment, as shown in FIG. 2, the pixels 20 are arranged in a honeycomb shape. Thereby, in the radiation detector 42 according to the present exemplary embodiment, the first pixel column in which a plurality of hexagonal pixels 20 having the same size are arranged in a predetermined direction, and the same size as the pixels 20 in the first pixel column. A plurality of hexagonal pixels 20 arranged in the predetermined direction are alternately arranged in a direction intersecting the predetermined direction, and the pixels 20 in the second pixel row are arranged in the first direction. Are arranged so as to correspond to each other between adjacent pixels in the first pixel column, so that they are arranged so as to be shifted by a half of the arrangement pitch of the respective pixels 20 in the first pixel column.

  Further, the honeycomb arrangement can be explained as follows when viewed in the row direction. A first pixel row in which a plurality of hexagonal pixels 20 having the same size are arranged in a predetermined direction, and a plurality of hexagonal pixels 20 having the same size as the pixels 20 in the first pixel row are arranged in the predetermined direction. The second pixel rows are alternately arranged in a direction crossing the predetermined direction, and the pixels 20 of the second pixel row are arranged correspondingly between adjacent pixels of the first pixel row. Therefore, they are arranged so as to be shifted by a half of the arrangement pitch of the pixels 20 in the first pixel row.

  When imaging the subject's breast, the hexagonal pixel is flattened and the breast is placed so that the shorter pixel width is along the direction from the chest wall toward the breast tip. You may make it do.

  Here, a specific example will be described. In the case of a flat hexagonal pixel, the pixel is crushed and flattened in the vertical direction of the drawing in FIG. 2 (the same applies to FIGS. 3 and 5A). Thereby, it becomes a suitable form for the mammography apparatus which image | photographs a chest wall corresponding to the upper part of the paper surface of FIG. This is because, in the case of a mammography apparatus, there is a need to obtain a high-definition depth direction from the chest wall side to the breast tip. Accordingly, the pixel is crushed in this direction (that is, in the hexagonal pixel, the length in the depth direction from the chest wall side to the tip of the breast is shorter than the width in the direction intersecting the direction), and the chest wall is flattened. If the external circuit such as the gate IC and the amplifier IC is not disposed on the side, the depth direction from the chest wall side to the tip of the breast can be photographed without leaving any resolution.

  In addition, when flattening a hexagonal pixel, one of the three diagonal lines passing through the center of the pixel is made longer than the other two diagonal lines, and the other two diagonal lines are equal in length. Are flattened (referred to as the first flattening method) so that one diagonal is shorter than the other two diagonals, and the other two diagonals are flat (first (Referred to as the flattening method 2). Specifically, for example, in FIG. 3, the diagonal length d (y) in the vertical direction of the paper is shorter than the other two diagonal lengths d (x) (that is, the vertical length of the paper is crushed in the vertical direction). It is preferable to flatten.

  First, in a regular hexagonal state where nothing is flattened, in FIG. 5A, the horizontal pixel arrangement pitch PP1 (x) is shorter than the vertical pixel arrangement pitch PP1 (y). Therefore, high resolution is ensured in the horizontal direction. While ensuring this resolution, by using the second flattening method to flatten the diagonal length d (y) in the vertical direction, not only the horizontal resolution but also the vertical resolution should be secured. Can do it.

  As shown in FIG. 2, each pixel 20 receives the irradiated radiation to generate a sensor unit 103 that generates charges, a charge storage capacitor 108 that stores charges generated by the sensor unit 103, and a charge storage capacitor 108 that stores the charges. And a TFT switch 109 for reading out the generated charges.

  One scanning line 101 is provided for each pixel column in the horizontal direction of the pixel 20 (hereinafter also referred to as a scanning wiring direction). The scanning wiring 101 is connected to the TFT switch 109 provided in each pixel 20 of the pixel column in the scanning wiring direction, and a control signal for switching each TFT switch 109 flows.

  Further, the signal wiring 107 is disposed so as to meander around the pixel 20 one by one in each pixel column with respect to the vertical direction of the pixel 20 (hereinafter also referred to as a signal wiring direction). The signal wiring 107 is connected to the TFT switch 109 of each pixel 20, and the charge stored in the charge storage capacitor 108 flows according to the switching state of the TFT switch 109.

  The radiation detector 42 according to the present embodiment is provided with a plurality of amplifier ICs 105 that detect an electrical signal flowing out to each signal wiring 3 on one end side in the signal wiring direction. Each signal wiring 3 is connected to the amplifier IC 105 for each predetermined first number (for example, 256).

  Further, the radiation detector 42 according to the present embodiment includes a plurality of gate ICs 104A that output control signals for turning on / off the TFT switch 109 to each scanning wiring 101 on both sides in the signal wiring direction across the detection region 40. , 104B are provided. Each scanning wiring 101 is alternately connected to the gate ICs 104A and 104B one by one at the other end, and another gate IC 104A and 104B for each predetermined second number (for example, 256). It is connected to the. In FIG. 2, the amplifier IC 105 and the gate ICs 104A and 104B are not shown one by one.

  The amplifier IC 105 includes an amplifier circuit that amplifies an input electric signal for each signal wiring 107. The amplifier IC 105 detects the amount of charge accumulated in each charge storage capacitor 108 as information of each pixel constituting the image by amplifying and detecting an electric signal input from each signal wiring 107 by an amplifier circuit. .

  A signal processing device 106 is connected to the amplifier IC 105 and the gate ICs 104A and 104B. The signal processing device 106 converts the electrical signal detected by the amplifier IC 105 into digital data and stores it in the storage unit 46D, and outputs a control signal indicating the timing of signal detection to the amplifier IC 105, and outputs to the gate IC 104 Then, a control signal indicating the output timing of the scan signal is output.

  FIG. 4 is a cross-sectional view showing the structure of the radiation detector 42.

  As shown in FIG. 4, in the radiation detector 42, the scanning wiring 101, the storage capacitor lower electrode 14, and the gate electrode 2 are formed on the insulating substrate 1. One scanning wiring 101 is arranged in a meandering manner so as to bypass the pixel 20 between the pixel columns, one for each pixel column with respect to the scanning wiring direction of the pixel 20. In addition to being connected to the formed gate electrode 2, it is connected to a storage capacitor lower electrode 14 formed in each pixel 20 of the lower pixel column. The wiring layer in which the scanning wiring 101, the storage capacitor lower electrode 14, and the gate electrode 2 are formed (hereinafter, this wiring layer is also referred to as “first signal wiring layer”) is made of Al or Cu, or Al or Cu. Although it is formed by using a main laminated film, it is not limited to these.

On the first signal wiring layer, an insulating film 15A is formed on one surface, and a portion located on the gate electrode 2 functions as a gate insulating film in the TFT switch 109. The insulating film 15A is made of, for example, SiN _X or the like, and is formed by, for example, CVD (Chemical Vapor Deposition) film formation.

  On the gate electrode 2 on the insulating film 15A, the semiconductor active layer 8 is formed in an island shape. The semiconductor active layer 8 is a channel portion of the TFT switch 109 and is made of, for example, an amorphous silicon film.

  A source electrode 9 and a drain electrode 13 are formed on these upper layers. In the wiring layer in which the source electrode 9 and the drain electrode 13 are formed, the signal wiring 107 is formed together with the source electrode 9 and the drain electrode 13, and at a position corresponding to the storage capacitor lower electrode 14 on the insulating film 15A. A storage capacitor upper electrode 16 is formed. The drain electrode 13 is connected to the storage capacitor upper electrode 16. The signal wiring 107 is connected to the source electrode 9 formed in each pixel 20. The wiring layer in which the source electrode 9, the drain electrode 13, the signal wiring 107, and the storage capacitor upper electrode 16 are formed (hereinafter, this wiring layer is also referred to as “second signal wiring layer”) is made of Al, Cu, or Al. Alternatively, it is formed using a laminated film mainly composed of Cu, but is not limited thereto. An impurity doped semiconductor layer (not shown) made of doped amorphous silicon or the like is formed between the source electrode 9 and drain electrode 13 and the semiconductor active layer 8. These constitute a switching TFT switch 109. In the TFT switch 109, the source electrode 9 and the drain electrode 13 are reversed depending on the polarity of charges collected and accumulated by the lower electrode 11 described later.

A TFT protective film layer 15B is formed on almost the entire area (substantially the entire area) of the area where the pixels on the substrate 1 are provided so as to cover these second signal wiring layers. The TFT protective film layer 15B is made of, for example, SiN _X or the like, and is formed by, for example, CVD film formation.

A coating type interlayer insulating film 12 is formed on the TFT protective film layer 15B. This interlayer insulating film 12 is made of a photosensitive organic material having a low dielectric constant (relative dielectric constant ε _r = 2 to 4) (for example, a positive photosensitive acrylic resin: a copolymer of methacrylic acid and glycidyl methacrylate). And a base polymer mixed with a naphthoquinonediazide-based positive photosensitive agent).

  In the radiation detector 42 according to the present exemplary embodiment, the interlayer insulating film 12 suppresses the capacitance between metals disposed in the upper layer and the lower layer of the interlayer insulating film 12 to be low. In general, such a material also has a function as a flattening film, and has an effect of flattening a lower step. In the radiation detector 42 according to the present embodiment, the contact hole 17 is formed at a position facing the storage capacitor upper electrode 16 of the interlayer insulating film 12 and the TFT protective film layer 15B.

  On the interlayer insulating film 12, the lower electrode 11 of the sensor unit 103 is formed so as to cover the pixel region while filling the contact hole 17 for each pixel 20. It is made of a conductive oxide film (ITO) and is connected to the storage capacitor upper electrode 16 through a contact hole 17. Therefore, the lower electrode 11 and the TFT switch 109 are electrically connected via the storage capacitor upper electrode 16.

  The semiconductor layer 6 is uniformly formed on almost the entire surface of the pixel region where the pixels 20 on the substrate 1 on the lower electrode 11 are provided. The semiconductor layer 6 generates charges (electrons-holes) inside when irradiated with radiation such as X-rays. That is, the semiconductor layer 6 has conductivity and is for converting image information by X-rays into charge information. The semiconductor layer 6 is made of, for example, amorphous a-Se (amorphous selenium) containing selenium as a main component. Here, the main component means having a content of 50% or more.

  An upper electrode 7 is formed on the semiconductor layer 6. The upper electrode 7 is connected to a bias power source (not shown), and a bias voltage is supplied from the bias power source.

  Next, the operation principle of the radiation detector 42 according to the present embodiment will be described.

  When the semiconductor layer 6 is irradiated with X-rays while a bias voltage is applied between the upper electrode 7 and the storage capacitor lower electrode 14, charges (electron-hole pairs) are generated in the semiconductor layer 6.

  The semiconductor layer 6 and the charge storage capacitor 108 are electrically connected in series. For this reason, electrons generated in the semiconductor layer 6 move to the + (plus) electrode side, and holes move to the-(minus) electrode side. At the time of image detection, an OFF signal (0 V) is output from the gate ICs 104 </ b> A and 104 </ b> B to all the scanning wirings 101, and a negative bias is applied to the gate electrode 2 of the TFT switch 109. As a result, each TFT switch 109 is held in the OFF state. As a result, electrons generated in the semiconductor layer 6 are collected by the lower electrode 11 and accumulated in the charge storage capacitor 108.

  At the time of image reading, one ON signal is sequentially output from the gate ICs 104 and 104B to each scanning wiring 101, and the ON signal (+10 to 20V) is sequentially applied to the gate electrode of the TFT switch 109 via the scanning wiring 101. Is done. As a result, the TFT switch 109 of each pixel 20 in each pixel column in the scanning wiring direction is sequentially turned on one by one, and an electric signal corresponding to the amount of charge accumulated in the charge storage capacitor 108 of each pixel 20 is signaled one by one. It flows out to the wiring 107.

  The amplifier IC 105 detects the amount of charge stored in the charge storage capacitor 108 of each sensor unit 103 based on the electrical signal flowing through each signal wiring 107 as information on the pixels constituting the image (hereinafter referred to as pixel information). Thereby, the image data which shows the image shown with the X-ray irradiated to the radiation detector 42 can be obtained.

  Image data obtained by the radiation detector 42 according to the present embodiment is image data representing an image in which each pixel is arranged in a honeycomb shape. On the other hand, many output devices such as printers and monitors (display device 80 in the present embodiment) are configured on the premise that they handle images in which each pixel is arranged in a square lattice. In 50, pixel density conversion is performed by performing interpolation processing on the image data representing the detected radiation image.

  However, when the radiation dose is small, sufficient sensitivity may not be obtained. At high frame rates such as moving images, not only the sensitivity problem but also the image processing of the detected radiation image is performed quickly. Therefore, the image processing apparatus 50 according to the present embodiment is detected from each pixel 20 in each pixel group for each pixel group in which a plurality of adjacent pixels 20 are combined. Image data in which each digital data (pixel value) stored in 46D is added (also referred to as binning), and an added value of each pixel 20 in the pixel group (that is, a total value of each pixel value) is used as a pixel value. The pixel density can be converted by performing an interpolation process on the image.

  Here, first, the processing contents when performing pixel density conversion without performing binning will be described. FIGS. 5A and 5B are diagrams schematically showing the contents of pixel density conversion processing when binning is not performed.

  As described with reference to FIGS. 2 and 3, since the hexagonal pixels are arranged in a honeycomb shape, the radiation image detected by the radiation detector 42 is as shown in FIG. Thus, an image in which each pixel is arranged in a honeycomb shape is obtained. Note that the black point drawn in the pixel is the pixel center of gravity.

  As shown in FIG. 5B, the image data representing the radiographic image is converted into image data representing an image in which a plurality of pixels are arranged in a square lattice pattern. At this time, the square lattice area S2 of the image after conversion is converted to be equal to or less than the area S1 of the hexagonal region before conversion. As the interpolation process performed by the pixel density conversion, a known interpolation process such as a nearest neighbor method, a linear interpolation method, or a bicubic interpolation method can be employed. Further, for example, the pixel density conversion method described in Japanese Patent Laid-Open No. 2000-244733 may be performed.

  In addition, the interpolation processing at the time of pixel density conversion is performed on the image data before the pixel density conversion by first performing the interpolation processing in the direction in which the pixel arrangement pitch is short in the horizontal direction and the vertical direction, and performing the interpolation processing in the other direction. It may be performed later. If the interpolation process is performed from the shorter distance, the accuracy is higher than that from the opposite direction, and the conversion speed is also increased.

  For example, as shown in FIG. 5A, when the horizontal pixel arrangement pitch PP1 (x) is shorter than the vertical pixel arrangement pitch PP1 (y), the horizontal interpolation processing is performed first. The vertical interpolation process is performed after the horizontal interpolation process. Conversely, when the vertical pixel arrangement pitch PP1 (y) is shorter than the horizontal pixel arrangement pitch PP1 (x), the vertical interpolation processing is performed first, and the horizontal interpolation processing is performed. Is performed after the horizontal interpolation process.

  Thereby, the information detected by the radiation detector 42 of the present embodiment can be fully utilized.

  Next, the processing content when performing pixel density conversion after binning will be described. Here, description will be made with reference to the flowchart shown in FIG. Note that the processing shown in this flowchart is performed by the CPU 60 of the image processing apparatus 50 executing a program stored in the ROM 62 or the HDD 66.

  In step 200, image data of a radiographic image captured by the radiation detector 42 of the imaging apparatus 41 and stored in the storage unit 46D is acquired. This acquisition may be configured to be automatically transferred to the image processing device 50 when the image data of the radiographic image captured by the imaging device 41 is stored in the storage unit 46D. A request for image data may be issued from the apparatus 50 to the photographing apparatus 41 at a predetermined timing, and the image data transmitted from the photographing apparatus 41 may be received in response to the request.

  In step 202, binning is performed for each predetermined pixel group based on the acquired image data. Here, as an example, binning is performed for each pixel group in which four pixels are combined. FIG. 7 shows an arrangement example of each pixel group. In FIG. 7, the fill pattern for each pixel of the adjacent pixel group is made different so that each pixel group can be easily distinguished (the same applies to FIGS. 8 to 14).

  In the example illustrated in FIG. 7, each pixel group includes three pixels arranged so that two adjacent sides of each pixel are adjacent to one side of each of the other two pixels, and each of the two adjacent sides. Is defined as a combination of four pixels composed of one pixel arranged so as to be adjacent to one side of each of the two pixels of the three pixels. In addition, in the combination of the four pixels, two sets of a pair of adjacent pixels are arranged side by side, and two adjacent sides of one pixel of one set are each of two pixels of the other set. It can be said that this is a combination of four pixels arranged adjacent to one side.

  In binning, the pixel values of the four pixels are added to obtain a total value, and first image data having each total value as a pixel value of one pixel is created. In pixel density conversion to be described later, the pixel value of the first image data is set to one pixel (hereinafter referred to as an actual pixel) in a region surrounded by the outline of the pixel group corresponding to the pixel value (the shape indicated by the broken line in FIG. 7). (Referred to as a binning pixel in order to distinguish it from the pixel 20).

  In FIG. 8, the barycentric position of the pixel group is indicated by a black dot. As shown in the figure, each center of gravity includes a hexagonal region (including region A in FIG. 8) formed by connecting one center of gravity inside and connecting six centers of gravity existing around the center of gravity. When a plurality of (see.) Are formed, the hexagonal regions are arranged adjacent to each other in a honeycomb shape.

  In other words, a first column in which a plurality of centroids of pixel groups are arranged in a predetermined direction and a second column in which a plurality of centroids of pixel groups are arranged in the predetermined direction at the same arrangement pitch as the first column are in the predetermined direction. Are alternately arranged in a direction intersecting with each other, and the centroids of the second column are arranged correspondingly between adjacent centroids of the first column. Thereby, the 1st row | line and the 2nd row | line | column are in the state which shifted | deviated 1/2 of arrangement pitch here.

  When viewed in the row direction, it can also be explained as follows. A first row in which a plurality of centroids of the pixel group are arranged in a predetermined direction and a second row in which a plurality of centroids of the pixel group are arranged in the predetermined direction at the same arrangement pitch as the first row intersect with the predetermined direction. The pixels are alternately arranged in the direction, and the centroids of the pixel groups in the second row are arranged correspondingly between adjacent centroids in the first row. Thereby, here, the first row and the second row are in a state shifted by ½ of the arrangement pitch.

  As described above, in the present embodiment, using the centroid of each region surrounded by the outline of the pixel group, the six centroids that include one centroid inside and that exist around the one centroid are represented by lines. The combination of pixels in each pixel group is determined so that when a plurality of hexagonal regions formed by connecting are formed adjacent to each other, the plurality of hexagonal regions formed are arranged in a honeycomb shape. ing. In this example, with this arrangement, in the hexagonal region A, the distances from the center of gravity located at the center to the six center of gravity arranged around are equal.

  In step 204, pixel density conversion is performed to convert the first image data into second image data representing an image in which a plurality of pixels are arranged in a square lattice pattern. In pixel density conversion performed after binning, interpolation processing is performed in the first image data in a direction where the arrangement pitch of the center of gravity of each pixel group (also referred to as binning pixel arrangement pitch) is short in the horizontal direction and the vertical direction. May be performed first, and interpolation processing in the other direction may be performed later.

  For example, as shown in FIG. 8, when the horizontal center of gravity arrangement pitch PP1 (x) is shorter than the vertical center of gravity arrangement pitch PP1 (y), the horizontal interpolation processing is performed first (see FIG. 8). 9 (A)), and the vertical interpolation processing is performed after the horizontal interpolation processing (see also FIG. 9B). Conversely, if the vertical center-of-gravity array pitch PP1 (y) is shorter than the horizontal center-of-gravity array pitch PP1 (x), the vertical interpolation processing is performed first, and the horizontal interpolation processing is performed. Is performed after the horizontal interpolation process.

  As described above, when the interpolation process is performed from the shorter distance, the accuracy is higher than when the interpolation process is performed from the opposite direction, and the conversion speed is also increased. Thereby, the information detected by the radiation detector 42 of the present embodiment can be fully utilized.

  Note that the interpolation processing method after binning may use a known method such as a nearest neighbor method, a linear interpolation method, or a bicubic interpolation method, similarly to the interpolation processing when binning is not performed.

  When displaying a radiation image on the display device 80, the image processing device 50 outputs the image data after the pixel density conversion thus obtained to the display device 80. The display device 80 displays a radiation image based on the image data after the pixel density conversion.

  As described above, the image data obtained by the radiation detector 42 in which hexagonal pixels are arranged in a honeycomb are binned for each pixel group to convert the pixel density. At this time, the pixel data is surrounded by the outline of the pixel group. When the center of gravity of each region is used and a plurality of hexagonal regions are formed adjacent to each other and formed by connecting the six centers of gravity existing around the center of gravity with a line. In addition, since the combination of each pixel of each pixel group is determined so that the plurality of formed hexagonal regions are arranged in a honeycomb shape, binning is performed in each of the horizontal direction, the vertical direction, and the diagonal direction. The bias of the subsequent pixel position (the barycentric position of the pixel group) can be suppressed, and the resolution can be ensured in each direction as in the image before binning.

  In addition, both the arrangement of the center of gravity before binning (see also FIG. 5A) and the arrangement of the center of gravity after binning (see also FIG. 8) are arranged in hexagonal regions formed by the center of gravity in a honeycomb shape. Therefore, even if pixel density conversion is performed after binning, it can be processed with the same algorithm as when performing pixel density conversion without binning, and pixel density conversion processing after binning processing Even if this algorithm is not manufactured separately, the pixel density conversion processing algorithm can be shared.

  In the above embodiment, an example in which binning is performed for each pixel group including four pixels has been described. However, the present invention is not limited to this. For example, as shown in FIG. 10, as a pixel group when binning a combination of three pixels arranged so that two adjacent sides of each pixel are adjacent to one side of each of the other two pixels. It may be determined and binned.

  In binning, the pixel values of these three pixels are added to obtain a total value, and first image data is created with each total value as the pixel value of one pixel. In the pixel density conversion, the pixel value of the first image data is regarded as a single pixel (binning pixel) in an area surrounded by the outline of the pixel group corresponding to the pixel value (the shape indicated by the broken line in FIG. 10). Is treated as the pixel value of each binning pixel.

  FIG. 11 shows the barycentric position of the pixel group corresponding to FIG. As shown in the figure, also in this example, each centroid includes a plurality of hexagonal regions formed by connecting six centroids existing around one centroid with lines. When the individual pieces are formed, the hexagonal regions are arranged so as to be adjacent and arranged in a honeycomb shape.

  In the pixel density conversion process, as shown in FIG. 11, the vertical center-of-gravity array pitch PP1 (y) is shorter than the horizontal center-of-gravity array pitch PP1 (x). The horizontal interpolation process may be performed after the vertical interpolation process.

  Further, for example, as shown in FIG. 12, a combination of seven pixels including one central pixel and six pixels located around the central pixel, each of the peripheral pixels being 1 A combination of seven pixels arranged so that the side is adjacent to any one of the central pixels may be defined as a pixel group for binning and binned.

  In binning, the pixel values of the seven pixels are added to obtain a total value, and first image data having each total value as a pixel value of one pixel is created. In the pixel density conversion, the pixel value of the first image data is regarded as a single pixel (binning pixel) in an area surrounded by the outline of the pixel group corresponding to the pixel value (the shape indicated by the broken line in FIG. 12). Is treated as the pixel value of each binning pixel.

  FIG. 13 shows the barycentric position of the pixel group corresponding to FIG. As shown in the figure, also in this example, each centroid includes a plurality of hexagonal regions formed by connecting six centroids existing around one centroid with lines. When the individual pieces are formed, the hexagonal regions are arranged so as to be adjacent and arranged in a honeycomb shape. In this example, the angle of the hexagonal region formed by the center of gravity is slightly inclined as compared with the three pixel groups and the four pixel groups described above, but it changes to a honeycomb-like arrangement. Absent.

  In the pixel density conversion process, as shown in FIG. 13, the horizontal center-of-gravity array pitch PP1 (x) is shorter than the vertical center-of-gravity array pitch PP1 (y). First, the vertical interpolation process may be performed after the horizontal interpolation process.

  As described above, even when a pixel group composed of a combination of three pixels and a pixel group composed of a combination of seven pixels are used, the same effect as in the case of using a pixel group composed of a combination of the four pixels can be obtained.

  In the above-described embodiment, the case where the pixels 20 arranged in the radiation detector 42 are regular hexagons has been described. However, by adopting regular hexagons in this way, horizontal, vertical, and diagonal before and after binning. Since each position of the center of gravity can be equally spaced in each direction, the effect is particularly high. That is, the position of the center of gravity of the regular hexagonal pixel 20 and the position of the center of gravity of the pixel group when binning are equally spaced in the horizontal direction, vertical direction, and diagonal direction, and the resolution is ensured without deviation in each direction. it can.

  Further, the pixels 20 arranged in the radiation detector 42 may be formed to have a flat hexagonal shape as described above instead of the regular hexagonal shape. Even when each pixel 20 is formed flat, binning may be performed in the same manner as described above to perform pixel density conversion. Even when flattened, the center of gravity of the pixel group maintains a hexagonal shape and is arranged in a honeycomb shape as described above, so that the positions of the center of gravity in each direction are not evenly spaced evenly. The bias is suppressed.

  The flatness ratio can be a value within a range in which a desired resolution can be obtained in each direction (even if binning is performed). Further, for example, the ratio between the pixel arrangement pitch of the image data after the pixel density conversion and the arrangement pitch of the center of gravity of each pixel group is a simple integer ratio (for example, 2: 3, 3: 5) and so on. This facilitates the interpolation process. For example, in FIG. 3, when flattening so that d (y) is shorter than d (x), the pixel arrangement pitch of the image data after pixel density conversion and the vertical arrangement pitch of the center of gravity of each pixel group By making a simple integer ratio, interpolation processing in the vertical direction can be facilitated.

  In addition, when a defective pixel is included in a plurality of pixels constituting the pixel group, an average value of pixel values of normal pixels excluding the defective pixel in the pixel group is used as the pixel value of the defective pixel. Then, the pixel values of the respective pixels in the pixel group may be added to obtain a total value of the pixel values of the pixel group.

  In this case, for example, before capturing a radiographic image, charge accumulation is performed for a certain period so that all pixels have a constant charge, and pixel values of all pixels are read without binning, and output abnormal values The pixel which showed is specified. Information indicating the pixel position is stored in advance in the storage unit 46D as the defective pixel, or stored in the HDD 66 of the image processing apparatus 50 or the like. When binning is performed by the image processing apparatus 50, information indicating the pixel position of the defective pixel is read out, and binning is performed as described above using pixel values of normal pixels excluding defective pixels in the pixel group.

  Furthermore, when all the pixels in the pixel group are defective pixels, binning may be performed after each pixel value of the defective pixel is obtained by interpolation processing using peripheral pixels.

  Furthermore, a combination of a plurality of pixels constituting each pixel group for binning may be set according to the radiation dose (hereinafter simply referred to as pixel group setting).

  When the pixel group is set according to the radiation dose, the radiation detector 42 is provided with a function for detecting the radiation dose. For example, a part of the pixel 20 of the radiation detector 42 may be used as a pixel used for detecting the irradiation state of radiation, and a radiation image may be captured by the remaining pixel 20. The radiation detection pixels may be provided dispersed in the detection region 40. Further, the radiation detection pixels may be stacked on the radiation detector 42 as a separate layer from the pixels 20.

  Here, the pre-digital-converted charges detected by the radiation detection pixels are acquired and combined, the combined electrical signal is digitally converted, and the digitally converted value is used as the radiation dose information indicating the radiation dose. Is stored in the storage unit 46D. A total value obtained by summing pixel values after being detected and digitally converted by the radiation detection pixels may be used as radiation dose information.

  FIG. 14 is a flowchart of a setting process that is performed by the image processing apparatus 50 and sets a pixel group according to the radiation dose. This setting process is executed after the radiographic image is taken and before binning is performed.

In step 300, radiation dose information is acquired from the imaging device 41.
In step 302, it is determined whether or not the radiation dose indicated by the radiation dose information exceeds a predetermined threshold. If the determination is affirmative, the process proceeds to step 304, and a pixel group having a small number of pixels is set as a pixel group for binning. On the other hand, if a negative determination is made, the process proceeds to step 306, where a pixel group having a larger number of pixels than the pixel group set in step 304 is set as a pixel group for binning. For example, in step 304, a pixel group including the three pixels is set, and in step 306, a pixel group including the four pixels or a pixel group including the seven pixels is set. For example, in step 304, a pixel group including the three pixels or a pixel group including the four pixels is set, and in step 306, a pixel group including the seven pixels is set.

  If the radiation dose is larger than the threshold value, sufficient sensitivity can be obtained, and it is not necessary to increase the number of pixels to be binned. On the other hand, if the radiation dose is less than or equal to the threshold, it is considered that the sensitivity is not sufficient, and therefore the number of pixels to be binned is increased. By setting the pixel group in accordance with the radiation dose in this way, a radiographed image can be obtained. In addition, two threshold values, a first threshold value and a second threshold value, are provided, and the magnitude relationship is set as follows: first threshold value <second threshold value, and if the radiation dose is equal to or less than the first threshold value, If a pixel group is set, and if the radiation dose is greater than the first threshold and less than or equal to the second threshold, a pixel group including four pixels is set, and if the radiation dose is greater than the second threshold, three pixels A pixel group including “” may be set. That is, the smaller the radiation dose, the greater the number of pixels to be binned.

  Furthermore, the image processing apparatus 50 is configured to perform either the first control for performing pixel density conversion by binning or the second control for performing pixel density conversion without binning according to the radiation dose. May be. Specifically, if the radiation amount detected as described above is equal to or less than a predetermined threshold value, as described in the above embodiment, a combination of a plurality of pixels (for example, a combination of four pixels) is included. Binning is performed for each pixel group, and control is performed so as to convert the pixel density (first control). If the detected radiation dose is larger than a predetermined threshold value, the pixel values obtained from the respective pixels 20 of the radiation detector 42 are not added as described with reference to FIG. (I.e., without binning) the third image data represented by the pixel value is interpolated so as to be the fourth image data representing an image in which a plurality of pixels are arranged in a square lattice. Control is performed so as to convert the pixel density (second control). Also by this, the radiographic image imaged favorably is obtained.

  In addition, as described above, the first threshold and the second threshold larger than the first threshold are provided, and the third threshold larger than the second threshold is provided. As described above, the first threshold and The number of pixels to be binned is set using the second threshold value, and when the radiation dose is larger than the third threshold value, the binning is set not to be performed, and the pixel density conversion is performed without binning (the second value). Control).

  Further, a pixel group for binning may be set according to a shooting mode for shooting a still image or a moving image. For example, when the mode is switched to a still image shooting mode for shooting a still image, a pixel group having a small number of pixels is set as a pixel group for binning. In addition, when the mode is switched to the moving image shooting mode for shooting a moving image, a pixel group having a larger number of pixels than the still image shooting mode is set as a pixel group for binning. As a result, in moving image shooting, it is possible to shoot at a high frame rate while ensuring sensitivity, the number of pixel values used when performing pixel density conversion is smaller than that of still images, and various image processing including pixel density conversion can be performed. It is possible to go quickly and output a moving image without delay.

  Furthermore, according to the shooting mode for shooting a still image or a moving image, either the first control for performing pixel density conversion by binning or the second control for performing pixel density conversion without binning is performed. The image processing apparatus 50 may be configured as described above. Specifically, when the mode is switched to the moving image shooting mode, as described in the above embodiment, binning is performed for each pixel group including a combination of a plurality of pixels (for example, a combination of four pixels). Control is performed so as to convert the pixel density (first control). Further, when the mode is switched to the still image capturing mode, as described with reference to FIG. 5, the pixel values obtained from the respective pixels 20 of the radiation detector 42 are not added (that is, binning is performed). The third image data represented by the pixel value is subjected to interpolation processing and pixel density conversion is performed so that the fourth image data representing an image in which a plurality of pixels are arranged in a square lattice pattern is obtained. Control (second control).

  Note that the arrangement state of the gate ICs 104A and 104B and the amplifier IC 105, the connection state of the signal wiring 107, and the connection state of the scanning wiring 101 in the above embodiment are examples, and are not limited to the above embodiment.

  For example, in the above-described embodiment, the radiation detector 42 in which the gate ICs 104A and 104B are arranged on the left and right sides with the detection region 40 interposed therebetween is described, but the present invention is not limited to this configuration. For example, as illustrated in FIG. 15, the gate ICs 104 </ b> A and 104 </ b> B may be arranged on both upper and lower sides with the detection region 40 interposed therebetween. The amplifier IC 105 is arranged on either the left or right side of the detection area 40. Also, as shown in FIG. 16, a gate IC 104 may be provided on either the left or right side of the detection region 40, and the amplifier IC 105 may be arranged in the same manner as in FIG.

  In the above embodiment, an example in which binning is performed for each pixel group in which four pixels are combined has been described with reference to FIGS. 7 to 9. It is not limited to. For example, they may be combined as shown in FIG. Also in this example, each pixel group has three pixels arranged such that two adjacent sides of each pixel are adjacent to one side of each of the other two pixels, and each of the two adjacent sides is the same. It is defined as a combination of four pixels composed of one pixel arranged so as to be adjacent to one side of each of two pixels of the three pixels. Further, in the combination of four pixels shown in FIG. 17, two pairs of adjacent pixels are arranged side by side, and two adjacent sides of one pixel of one set are two pixels of the other set. It can be said that it is a combination of four pixels arranged so as to be adjacent to one side of each.

  In binning, the pixel values of the four pixels are added to obtain a total value, and first image data having each total value as a pixel value of one pixel is created. In the pixel density conversion, the pixel value of the first image data is regarded as a single pixel (binning pixel) in an area surrounded by the outline of the pixel group corresponding to the pixel value (the shape indicated by the broken line in FIG. 17). Is treated as the pixel value of each binning pixel.

  In FIG. 18, the barycentric position of the pixel group corresponding to FIG. 17 is indicated by a black dot. As shown in the figure, also in this example, each centroid includes a plurality of hexagonal regions formed by connecting six centroids existing around one centroid with lines. When the individual pieces are formed, the hexagonal regions are arranged so as to be adjacent and arranged in a honeycomb shape.

  In the pixel density conversion process, as shown in FIG. 18, the horizontal center-of-gravity array pitch PP1 (x) is shorter than the vertical center-of-gravity array pitch PP1 (y). The vertical interpolation process may be performed after the horizontal interpolation process.

  Moreover, although the case where it applied to the radiation detector 42 of a direct conversion system was demonstrated in the said embodiment, you may apply to the radiation detector 42 of an indirect conversion system.

  In the above embodiment, the image processing apparatus 50 is provided with the functions of an adding means for performing binning (addition of pixel values) and a pixel density converting means for performing pixel density conversion. Although the example comprised as an apparatus independent of the imaging device 41 containing was demonstrated, it is not limited to this. For example, the addition unit and the image density conversion unit, or a part of the image processing apparatus 50 that has an image processing function for performing binning and pixel density conversion may be provided in the radiation detector 42. As another example, a system in which the photographing apparatus 41 and an image processing apparatus 50 that performs binning and pixel density conversion are connected via a network may be used.

  Moreover, although the said embodiment demonstrated the case where this invention was applied to the radiation detector 42 which detects an image by detecting an X-ray as a radiation to be detected, this invention is limited to this. Instead, for example, the radiation to be detected may be visible light, ultraviolet light, infrared light, or the like.

  In the above embodiment, the radiation detector 42 has been described with respect to the case where each pixel 20 includes the charge storage capacitor 108. However, for example, when the lower electrode 11 has a capacity capable of sufficiently storing charges, each pixel 20 In some cases, the charge storage capacitor 108 is not formed.

  In addition, the configuration of the radiographic imaging system 100 described in the above embodiment, the configuration of the radiation detector 42, and the like are merely examples, and it goes without saying that they can be appropriately changed without departing from the gist of the present invention.

41 imaging device 42 radiation detector 20 pixel 50 image processing device 80 display device 100 radiation image imaging system

Claims (13)

A radiation detector in which a plurality of hexagonal pixels of the same size for detecting radiation are arranged in a honeycomb shape; and
For each pixel group combining a plurality of adjacent pixels of the radiation detector, an adding means for adding the pixel values of each pixel in each pixel group;
Interpolation processing is performed so that the first image data having a pixel value that is the sum of pixel values of each pixel in the pixel group becomes second image data representing an image in which a plurality of pixels are arranged in a square lattice pattern. Pixel density conversion means to perform,
With
The adding means is formed by using the centroid of each region surrounded by the outline of the pixel group and connecting one centroid inside and connecting six centroids existing around the one centroid with lines. The combination of pixels in the pixel group is defined so that when a plurality of hexagonal regions are formed adjacent to each other, the plurality of hexagonal regions formed are arranged in a honeycomb shape. Radiation imaging device. 2. The pixel density conversion unit performs interpolation processing in the first image data in a direction in which the arrangement pitch of the center of gravity is short among the horizontal direction and the vertical direction first, and performs interpolation processing in the other direction later. Radiographic imaging device. The radiographic image capturing apparatus according to claim 1, wherein the hexagonal pixel is formed to have a regular hexagonal shape. The radiographic imaging device according to claim 1, wherein the hexagonal pixels are formed to have a flat hexagonal shape. In the case where the radiographic imaging device is used as a mammography device for imaging a breast of a subject, the hexagonal pixel has a length in the depth direction from the chest wall side to the breast tip in a direction intersecting the direction. The radiographic image capturing apparatus according to claim 4, wherein the radiographic image capturing apparatus is flattened so as to be shorter than a width. The hexagonal pixel is flattened so that one of the three diagonal lines passing through the center of the pixel is shorter than the other two diagonal lines, and the other two diagonal lines have the same length. The radiographic imaging device according to claim 4 or 5, wherein the radiographic imaging device is formed. A second pixel that performs interpolation processing so that third image data composed of pixel values of each pixel of the radiation detector becomes fourth image data representing an image in which a plurality of pixels are arranged in a square lattice pattern. Density conversion means;
A first control for controlling the addition of pixel values by the adding means and the interpolation processing by the pixel density converting means in accordance with a photographing mode for photographing a still image or a moving image or a radiation dose. And a control means for performing control of either one of the second control for performing control so that the interpolation processing is performed by the second pixel density conversion means without adding the pixel values in the adding means,
The radiographic imaging apparatus according to claim 1, further comprising: 7. The apparatus according to claim 1, further comprising a setting unit configured to set a combination of a plurality of pixels constituting each of the pixel groups according to a shooting mode for shooting a still image or a moving image or a radiation dose. The radiographic imaging apparatus according to item 1. When the defective pixel is included in the pixel group, the adding means uses an average value of pixel values of normal pixels excluding the defective pixel in the pixel group as a pixel value of the defective pixel. The radiation imaging apparatus according to claim 1, wherein the radiation imaging apparatus is added. A combination of a plurality of pixels constituting each of the pixel groups is
A combination of three pixels arranged so that two adjacent sides of each pixel are adjacent to one side of each of the other two pixels,
A combination of four pixels comprising the three pixels and one pixel arranged such that each of two adjacent sides is adjacent to one side of each of the two pixels of the three pixels; and A combination of seven pixels consisting of six central pixels and six pixels located around the one central pixel, each side of the peripheral pixels being one side of the central pixel The radiographic imaging device according to any one of claims 1 to 9, wherein the radiographic imaging device is a combination of seven pixels arranged adjacent to each other. Furthermore, a radiation source for irradiating radiation,
An image output device that outputs an image based on the second image data;
The radiographic imaging apparatus of any one of Claims 1-10 provided with these. The pixel value of each pixel in each pixel group is added for each pixel group obtained by combining a plurality of adjacent pixels of a radiation detector in which a plurality of hexagonal pixels of the same size for detecting radiation are arranged in a honeycomb shape. Adding step;
Interpolation processing is performed so that the first image data having a pixel value that is the sum of pixel values of each pixel in the pixel group becomes second image data representing an image in which a plurality of pixels are arranged in a square lattice pattern. A pixel density conversion step to be performed;
With
In the adding step, the center of gravity of each region surrounded by the outline of the pixel group is used to form one centroid inside and connecting the six centroids existing around the one centroid with lines. The combination of pixels in the pixel group is defined so that when a plurality of hexagonal regions are formed adjacent to each other, the plurality of hexagonal regions formed are arranged in a honeycomb shape. Radiation imaging method. In the pixel density conversion step, in the first image data, interpolation processing in a direction in which the arrangement pitch of the center of gravity of each region is short in the horizontal direction and the vertical direction is performed first, and interpolation processing in the other direction is performed later. Item 13. A radiographic imaging method according to Item 12.