JP2017086335A - Radiographic system and radiographic method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiographic system and a radiographic method capable of improving the image quality of a long-sized image containing defective regions due to structures of radiation detectors.SOLUTION: The present invention relates to a radiographic system comprising: plural radiation detectors 120, 122, 124 for detecting radiation; and a synthetic processing unit for generating a long-sized image by synthesizing plural radiation images captured from the plural radiation detectors which are partially overlapped with each other, the radiographic system further comprising a masking unit for masking the structures of the radiation detectors in detective regions of the long-sized image caused by the radiation detectors being overlapped with each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radiation imaging system and a radiation imaging method for performing imaging using radiation.

  In recent years, in the medical field, imaging with a wide observation area (hereinafter referred to as long imaging), such as imaging the entire spinal cord or lower limbs of the subject or the whole body, has been performed. Patent Document 1 discloses a radiation imaging system that can perform long imaging by imaging a plurality of radiation detection devices (radiation imaging devices) side by side.

JP2012-040140A

  In Patent Document 1, when imaging a plurality of radiation detection devices side by side while overlapping a part of the radiation detection device, radiation disposed at a position close to the radiation generation unit in a radiation detection device disposed at a position far from the radiation generation unit A part of the detection device is reflected. That is, the structure of the other radiation detection apparatus is reflected in the radiation image output from one radiation detection apparatus. The structure of the radiation detection apparatus in the radiographic image has a structure that is not related to the subject who is a diagnosis target, and can be said to be a defective area. The defective area remains as a long image (composite image) by combining a plurality of radiation images. However, Patent Document 1 does not mention measures against this reflection.

  Therefore, an object of the present invention is to provide a radiation imaging system and a radiation imaging method for improving the image quality of a long image including a defect region caused by a structure of a radiation detection apparatus.

  In order to achieve the object of the present invention, a plurality of radiation detection devices for detecting radiation and a plurality of radiation images acquired from a plurality of radiation detection devices arranged to overlap a part of the radiation detection device are synthesized. In a radiation imaging system having a composition processing unit for generating a long image, a mask process is performed on a structure of the radiation detection device in a defect region of a long image generated by overlapping the radiation detection device. A mask processing unit is provided.

  According to the present invention, it is possible to improve the image quality of a long image (composite image) including a defect area caused by the structure of the radiation detection apparatus.

The figure which shows schematic structure of the radiography system of this invention. The figure which shows the relationship between the radiation detection apparatus of the radiography system of this invention, and image data. The figure which shows the structure of the radiography system (mainly image display control part) of this invention. The figure which shows the relationship between the radiation detection apparatus of the radiography system of this invention, and image data. The figure which shows the defect area | region of the elongate image of the radiography system of this invention. The figure explaining the process in the synthetic | combination process part of the radiography system of this invention. The figure explaining the process in the synthetic | combination process part of the radiography system of this invention. The figure explaining the process in the image correction part of the radiography system of this invention. The figure explaining the process in the mask process part of the radiography system of this invention. The flowchart which shows operation | movement of the radiography system of this invention. The figure which shows the structure of the radiography system (mainly image display control part) of this invention.

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

  FIG. 1 is a diagram showing a schematic configuration of a radiation imaging system of the present invention. It is a figure which shows schematic structure of the radiography system used for the long imaging | photography performed by arranging a some radiation detection apparatus side by side.

  The radiation imaging system includes a radiation generation unit 112 that generates radiation. The radiation generating unit 112 can irradiate the irradiation range 114 with radiation. The radiation generating unit 112 is installed via a support unit (not shown) installed on the floor or ceiling. A diaphragm (not shown) that shields radiation is installed on the irradiation surface of the radiation generator 112. The operator can set the irradiation range 114 of the radiation irradiated from the radiation generation unit 112 by controlling the diaphragm that shields the radiation.

  The radiation imaging system includes a plurality of radiation detection devices 120, 122, and 124. Here, although the form provided with the three radiation detection apparatuses 120, 122, and 124 is shown, two radiation detection apparatuses and four or more radiation detection apparatuses may be sufficient. The plurality of radiation detection devices 120, 122, and 124 detect radiation that has passed through the subject 100 and output image data corresponding to the radiation. Note that image data can also be referred to as a radiation image.

  Specifically, the plurality of radiation detection devices 120, 122, and 124 detect the radiation that has passed through the subject as charges corresponding to the amount of transmitted radiation. For example, the plurality of radiation detection devices 120, 122, and 124 include a direct conversion sensor that directly converts radiation such as a-Se that converts radiation into charges, a scintillator such as CsI, and a-Si. An indirect sensor using a photoelectric conversion element is used. Further, the plurality of radiation detection devices 120, 122, and 124 generate image data by A / D converting the detected charges and output the image data to the image display control unit 130.

  The plurality of radiation detection devices 120, 122, and 124 are accommodated in the imaging table 110. The imaging stand 110 is a rectangular casing, and the inside of the casing is hollow. In addition, the imaging stand 110 has a function of holding a plurality of radiation detection devices 120, 122, and 124.

  As shown in FIG. 1, the photographing stand 110 is installed with the photographing stand 110 standing upright with respect to the floor. The subject 100 is installed along the longitudinal direction of the imaging table 110. The imaging stand 110 has a support function for supporting the subject 100.

  In FIG. 1, the imaging table 110 is installed so that the longitudinal direction of the imaging table 110 is a vertical direction, that is, the imaging table 110 stands upright with respect to the floor surface. Note that the imaging table 110 may be installed so that the longitudinal direction of the imaging table 110 is in the horizontal direction, that is, the imaging table 110 is parallel to the floor surface.

  On the imaging table 110, a radiation detection device 120, a radiation detection device 122, and a radiation detection device 124 are arranged along the longitudinal direction of the imaging table 110. At this time, a plurality of radiation detection devices are arranged while overlapping a part of the radiation detection devices. For example, as illustrated in FIG. 1, the radiation detection device 120 and the radiation detection device 122 are arranged so that a part thereof overlaps with each other in space. At this time, the imageable areas of the radiation detection device 120 and the radiation detection device 122 overlap each other. Similarly, the radiation detection device 122 and the radiation detection device 124 are arranged so that a part thereof is spatially overlapped with each other. At this time, the imageable areas of the radiation detection device 122 and the radiation detection device 124 overlap each other. Further, the radiation detection device 122 is disposed on the back side of the radiation detection device 120 and the radiation detection device 124, that is, at a position far from the radiation generation unit 112.

  The radiation imaging system performs image processing on the image data output from the radiation detection apparatus, and issues an instruction from an image display control unit 130 that generates an image, a display unit 132 that displays an image, and an operator. And an operation unit 134. The image display control unit 130 has a function of controlling each component.

  The image display control unit 130 is connected to a plurality of radiation detection devices 120, 122, and 124. Specifically, the image display control unit 130 is connected to the plurality of radiation detection devices 120, 122, and 124 by a wired or wireless network or a dedicated line. The plurality of radiation detection devices 120, 122, and 124 capture the radiation generated by the radiation generation unit 112 and output the image data to the image display control unit 130. The image display control unit 130 has an application function that operates on a computer. The image display control unit 130 outputs an image to the display unit 132 or outputs a graphical user interface while controlling operations of the plurality of radiation detection devices 120, 122, and 124.

  The image display control unit 130 controls the radiation generation timing and radiation imaging conditions of the radiation generation unit 112. The image display control unit 130 also controls the timing for capturing and outputting the image data of the plurality of radiation detection devices 120, 122, and 124. The image display control unit 130 can cause the plurality of radiation detection devices 120, 122, and 124 to perform imaging simultaneously, and can cause the plurality of radiation detection devices 120, 122, and 124 to output image data simultaneously.

  The image display control unit 130 has a function of performing image processing such as gradation processing and noise removal on image data output from the plurality of radiation detection devices 120, 122, and 124. The image display control unit 130 can also perform image processing such as trimming and rotation on images output from the plurality of radiation detection devices 120, 122, and 124. The display unit 132 displays the image output from the image display control unit 130.

  The subject 100 stands on a platform placed on the imaging table 110 and is positioned with respect to the plurality of radiation detection devices 120, 122, 124 and the radiation generation unit 112. In this embodiment, the angle is such that the radiation enters the center of the radiation detector 122 perpendicularly. The radiation irradiated from the radiation generation unit 112 toward the plurality of radiation detection devices 120, 122, 124 reaches the plurality of radiation detection devices 120, 122, 124 through the subject 100 and is detected. Image data obtained by the plurality of radiation detection devices 120, 122, and 124 are combined by the image display control unit 130, and a combined image of the subject 100 is generated. The composite image is a long image acquired by long shooting with a wide observation area. The display unit 132 displays a long image output from the image display control unit 130.

  With the radiation imaging system of the present invention, it is possible to perform long imaging for imaging the entire spinal cord and lower limbs of the subject 100 or the whole body by one irradiation of radiation. The radiation (irradiation range 114) irradiated from the radiation generation unit 112 is simultaneously irradiated to the plurality of radiation detection devices 120, 122, and 124. For example, the operator controls a diaphragm that shields radiation, or adjusts the distance between the plurality of radiation detection devices 120, 122, and 124 and the radiation generation unit 112.

  Note that the plurality of radiation detection devices 120, 122, and 124 may have a detection function that automatically detects radiation irradiation from the radiation generation unit 112. The detection function for automatic detection is a function in which, when radiation is emitted from the radiation generation unit 112, the plurality of radiation detection devices 120, 122, and 124 detect radiation and accumulate electric charges caused by the radiation. When radiation irradiation is detected by one of the plurality of radiation detection devices 120, 122, and 124, the plurality of radiation detection devices 120, 122, and 124 start the main reading operation and acquire image data.

  In the radiation imaging system described above, the radiation detection device 122 is disposed so as to overlap behind the radiation detection devices 120 and 124. For this reason, the image data output from the radiation detection device 122 includes radiation detection panels, substrates, fasteners (for example, screws), packing members, buffer members, circuits, housings, which are internal components of the radiation detection devices 120 and 124. A defect area in which a structure (structure information) such as a body is reflected is generated. These components are structures having a low radiation transmittance of the radiation detection apparatus. This defective area will be described with reference to FIG. 2 showing the relationship between the radiation detection apparatus of the radiation imaging system of the present invention and a radiation image.

The radiation detection device 120 includes a radiation detection panel 150 that detects radiation and an adhesive material 156 that adheres the radiation detection panel 150 and places the radiation detection panel 150 on the panel base 158 from the radiation incident surface side. The radiation detection apparatus 120 includes a combined body in which a panel base 158 that supports the radiation detection panel 150 and a control board 154 that outputs an electrical signal from the radiation detection panel 150 are stacked in this order. The radiation detection panel 150 and the control board 154 are connected via a flexible board 152.

  The outer casing of the radiation detection device 120 includes a metal casing 160 made of metal and a radiation transmitting portion 162 made of a radiation transmitting member that transmits radiation. A radiation transmitting part 162 is installed on the radiation incident surface of the radiation detection panel 150 to suppress the attenuation of radiation from the radiation generating part 112. The radiation detection panel 150 has an effective pixel region capable of detecting radiation and a peripheral edge on the outer periphery of the effective pixel region.

  Although not described, the radiation detection device 122 and the radiation detection device 124 have the same configuration as the radiation detection device 120.

  The radiation detection device 122 is arranged so that the effective pixel region partially overlaps the effective pixel region of the radiation detection device 120, and any effective pixel region of the radiation detection device 120 or 122 is reliably image information in any line. Configured to get. The long image includes image data (radiation image) output from the radiation detection device 120 and image data (radiation) of an image area that is not acquired by the radiation detection device 120 among the image data output from the radiation detection device 122. Image).

  Here, the structure of the radiation detection device 120 is reflected in the image data 302 acquired from the radiation detection device 122. A region 410 from the end of the effective pixel region of the radiation detection device 122 to the end of the exterior housing of the radiation detection device 122 is a region where the structure of the radiation detection device 120 is reflected in the radiation detection device 122. In the image data 302 acquired from the radiation detection device 122, a defect region 412 is generated due to the reflection of the structure of the radiation detection device 120. That is, in the synthesis processing unit 142, a defective area 412 is also generated in a long image generated from the image data 302 acquired from the radiation detection device 122.

  In the defect area 412 of the image data 302 acquired from the radiation detection device 122, the radiation detection panel 150, the flexible substrate 152, the adhesive material 156, the panel base 158, and a part of the metal casing 160 in the radiation detection device 120 are image information. Included as Further, the defect area 412 includes structures (structure information) such as substrates, fasteners (for example, screws), packing members, buffer members, circuits, and cases as image information. Further, the defect area 412 includes image information caused by the substrate on the flexible substrate 152, the fastener 414, the fastener 416, and the like. The fasteners 414 and 416 are, for example, members that fasten the radiation detection panel 150 and the panel base 158 so as not to be misaligned, and members that fasten the radiation transmitting portion 162 and the housing 160 so as not to misalign. The fastener 414 and the fastener 416 are structures that hold a plurality of components of the radiation detection apparatus 120.

  As shown in FIG. 2, the effective pixel areas of the radiation detection device 120 and the radiation detection device 122 partially overlap. Among the image data 302, the region of the fastener 414 is a region acquired by the image data 300 acquired from the radiation detector 120. For the area of the fastener 414, there is no need to perform correction processing and mask processing described later. That is, the region of the fastener 414 is a portion that does not become a defective region on the long image. On the other hand, the area of the fastener 416 in the image data 302 is a part that becomes a defect area 410 because it is an area acquired only by the radiation detector 122.

  In the image data 302 acquired from the radiation detection apparatus 122, a defect area 410 is generated due to the reflection of the structure of the radiation detection apparatus 120. Similarly, in the image data 302 acquired from the radiation detection device 122, a defect area is generated due to the reflection of the structure of the radiation detection device 124.

  As described above, the defect area is a loss of image information caused by a structure having a low radiation transmittance, and the subject information is lost from the defect area. Therefore, the defective area may be an obstacle during diagnosis using a long image.

  Next, with reference to the block diagram of the radiation imaging system of the present invention shown in FIG. 3, a mode for improving the image quality by reducing the defect area of the long image caused by the above-described superposition of the radiation detection apparatuses will be described.

  The image display control unit 130 includes a storage unit 140 that stores image data output from a plurality of radiation detection apparatuses, and a synthesis processing unit 142 that combines the plurality of image data to generate a long image. The image display control unit 130 further includes an image correction unit 146 that corrects a defect area generated in the long image so as not to be noticeable, and a gradation that performs gradation processing on the long image corrected by the image correction unit 146. And a processing unit 148. The image display control unit 130 further includes a mask processing unit 150 that performs a mask process on the structure of the radiation detection device in the defect region of the long image generated by overlapping the radiation detection devices.

  The storage unit 140 stores image data (radiation images) output from the plurality of radiation detection devices 120, 122, and 124. As shown in FIG. 3, the radiation detection devices 120, 122, and 124 are a radiation detection device (D1), a radiation detection device (D2), and a radiation detection device (D3), respectively.

  The storage unit 140 can store image data output from the radiation detection devices 120, 122, and 124 together with time information. Therefore, the memory | storage part 140 can distinguish and memorize | store whether the radiographic image output from the radiation detection apparatus 120,122,124 was acquired simultaneously by the time information when the radiographic image was acquired. The storage unit 140 can distinguish and store whether the image is a radiographic image including the image information of the subject or a radiographic image not including the image information of the subject.

  In addition, the storage unit 140 can store a plurality of radiation images simultaneously captured by the plurality of radiation detection devices 120, 122, and 124 in association with position information (arrangement information) of the radiation detection device. For example, the storage unit 140 can store the image data output from the radiation detection apparatus 120 and the image data output from the radiation detection apparatus 122 in association with each other. Similarly, the storage unit 140 can store the image data output from the radiation detection device 122 and the image data output from the radiation detection device 124 in association with each other. Furthermore, the storage unit 140 can store the radiation detection device 122 in association with the fact that the radiation detection device 122 is disposed on the back side of the radiation detection devices 120 and 124. The storage unit 140 can output a plurality of image data and its position information to the composition processing unit 142.

  The composition processing unit 142 synthesizes a plurality of image data stored in the storage unit 140 to generate a long image. At this time, the synthesis processing unit 142 synthesizes a plurality of pieces of image data including the image information of the subject 100 to generate a long image.

  The combination processing unit 142 generates a long image by combining the plurality of image data output from the radiation detection apparatuses 120, 122, and 124 based on the position information. Specifically, the synthesis processing unit 142 determines a plurality of image data (radiation images) output simultaneously from the radiation detection devices 120, 122, and 124 based on time information as a synthesis target, and synthesizes the plurality of image data. To do. The synthesis processing unit 142 determines and synthesizes the positional relationship of the plurality of image data output from the radiation detection devices 120, 122, and 124 based on the position information.

  For example, in the example shown in FIG. 1, the image data output from the radiation detection device 120 is upward, the image data output from the radiation detection device 124 is downward, and the image data output from the radiation detection device 122 is between them. Positioned. Further, the composition is performed in consideration of the overlapping method indicated by the position information. For example, in the radiation detection device 122 disposed so as to overlap with another radiation detection device at a position far from the radiation generation unit 112, defective areas are generated in the upper and lower sides. However, no defect area occurs in the radiation detection devices 120 and 124. Therefore, the composition processing unit 142 generates a long image using image data generated by the radiation detection devices 120 and 124 within a range where the radiation detection devices overlap, thereby minimizing the area of the defect region generated in the long image. be able to. As described above, the composition processing unit 142 can generate a long image by combining a plurality of image data obtained by photographing a plurality of adjacent photographing regions.

  The image correction unit 146 performs processing for correcting the defect area so as not to be conspicuous with respect to the composite image output from the composite processing unit 142. Specifically, the image correction unit 146 corrects the defect area of the long image using the pixel value distribution of the normal area adjacent to the defect area. In other words, the image correction unit 146 corrects the defect area of the long image using information on a normal image area adjacent to the defect area.

  The structure is information representing the structure of the radiation detection apparatus that may be reflected in the radiation image. The structure includes information such as a radiation source weak coefficient, a thickness, and a position of a substance existing inside the radiation detection apparatus. When correcting a defective area on a long image, it is expected that the edge of the defective area has a correlation if there is no reflection with the pixel value distribution of a normal area spatially adjacent. Therefore, the image correction unit 146 corrects the defective area by performing correction so that the pixel value distribution of the defective area approaches the pixel value distribution of the normal area in consideration of the structure in which the reflection occurs.

  Here, in order to simplify the description, a method will be described in which image data obtained by superimposing a plurality of radiation detection devices in a state where there is no subject is acquired and used as a structure. In the structure, the reflection of the structure of the radiation detection apparatus is expressed in the form of a pixel value. This pixel value is, for example, a small value for a pixel in which reflection is caused by a thick structure having a large radiation source weak coefficient, and a large value for a pixel in which reflection is caused by a thin structure having a small radiation source weak coefficient.

  A case where a structure is included in the image data will be described with reference to FIG. FIG. 4 schematically shows the configuration of the radiation imaging system of the present invention and the form of image data (including defect areas). When a plurality of radiation detection devices 120, 122, and 124 are arranged in the form shown in FIG. 4 and imaging is performed without a subject, the radiation detection device 120 is included in the image data 302 acquired from the radiation detection device 122. , 124 are reflected.

  Specifically, the image data 302 acquired from the radiation detection device 122 includes a structure reflection region 306 at the lower end of the overlapping radiation detection device 120. Further, the image data 302 acquired from the radiation detection device 122 includes a structure reflection region 308 at the upper end of the overlapping radiation detection device 124.

  In addition, in the image data (radiation image) 300 acquired from the radiation detection apparatus 120, the reflection of the structure of another radiation detection apparatus does not arise. In addition, the image data (radiation image) 304 acquired from the radiation detection device 124 is not reflected in the structures of other radiation detection devices. Therefore, the image data 302 corresponds to structure data having a reflection method on the image as position / pixel value information. The reflection area 306 and the reflection area 308 can also be regarded as structures.

  The position of the defect area on the long image may be obtained from the position information of the radiation detection apparatus held by the storage unit 140, but can also be obtained using a structure. That is, if an information defect that occurs on the long image indicated by the structure is detected on the long image, the detected area is a defective area. For example, when the above-described reflection areas 306 and 308 are used as a structure, the image correction unit 146 and the mask processing unit 15 perform template matching on the long image using the structure as a template image. Then, the position having the highest correlation is acquired as a defect area, and is set as a correction target by the image correction unit 146 and the mask processing unit 150.

  FIG. 5 is a diagram showing correction processing in the image correction unit 146 of the radiation imaging system of the present invention. In particular, the present invention shows a mode in which a defect area (image defect area) based on reflection of structures of the radiation detection apparatus 120 and the radiation detection apparatus 124 is reduced from image data.

  FIG. 5A shows a long image 510 generated by combining a plurality of image data (radiation images) by the combining processing unit 142. The long image 510 is generated by the synthesis processing unit 142 and output to the image correction unit 146.

  FIG. 5B illustrates an example of a structure used for correction processing in the image correction unit 146. Here, imaging is performed without the subject 100, and image data acquired from the radiation detection apparatus 122 is the structure 302.

  FIG. 5C is a corrected long image 512 in which the defect area in which the structures of the radiation detection device 120 and the radiation detection device 124 are reflected is corrected with respect to the long image 510 in FIG. . The corrected long image 512 is an output of the image correction unit 146. An image 500 shown in FIG. 5A is image data output from the radiation detection apparatus 120, and mainly includes the head and shoulders of the subject 100 in this example. Subsequently, an image 502 illustrated in FIG. 5A is image data output from the radiation detection apparatus 122, and mainly includes the body and the hand of the subject 100 in this example. At the upper end and lower end of the image 502, the structures of the radiation detection devices 120 and 124 are reflected, and a defective area is generated. The composition processing unit 142 performs composition so that the area occupied by the defective area on the long image is minimized based on the arrangement relationship of the radiation detection units.

  An image 504 shown in FIG. 5A is image data output from the radiation detection device 124. In this example, the leg portion of the subject 100 is mainly included.

  As shown in FIG. 5A, the composition processing unit 142 obtains a whole body image of the subject 100 by synthesizing the image 500, the image 502, and the image 504 to generate a long image 510.

  As shown in FIG. 5C, the image correction unit 146 has a defect area due to the reflection of the structures of the radiation detection device 120 and the radiation detection device 124 with respect to the long image 510 shown in FIG. Correction processing for reducing the above is performed. That is, the image correction unit 146 generates a long image 512 in which a defect area in which a part of the radiation detection apparatus (a structure of the radiation detection apparatus) is reflected is corrected.

  Here, the synthesis processing of the synthesis processing unit 142, the correction processing of the image correction unit 146, and the mask processing of the mask processing unit 150 will be described in detail with reference to FIGS.

  6 and 7 are diagrams for explaining the synthesis process of the synthesis processing unit 142. FIG. 8 is a diagram for explaining the correction processing of the image correction unit 146. FIG. 9 is a diagram for explaining the mask processing of the mask processing unit 150.

  6 and 7 are enlarged views of the broken line region 600 of FIG. 8 and 9 are enlarged views of the broken line region 700 in FIG.

  In FIG. 6, the image data 302 acquired from the radiation detection device 122 is overwritten to the near side of the image data 300 acquired from the radiation detection device 120. Since the radiation detection device 122 is arranged on the back side of the radiation detection device 120, that is, at a position far from the radiation generation unit 112, the structure of the radiation detection device 120 exists in the image data 302 of the radiation detection device 120. . When the image data 302 is overwritten on the front side of the image data 300, a structure in a region where the image data 300 and the image data 302 overlap is displayed. That is, the defect area in the long image is widened.

  Therefore, as illustrated in FIG. 7, the synthesis processing unit 142 overwrites the image data 300 acquired from the radiation detection apparatus 120 on the near side of the image data 302 acquired from the radiation detection apparatus 122. The composition processing unit 142 overwrites the image data 300 in front of the image data 302 to generate a long image. As shown in FIG. 7, the long image includes image data 500 based on the image data 300 and image data 502 based on the image data 302.

  As described above, the composition processing unit 142 generates the long image using the image data generated by the radiation detection devices 120 and 124 in the range where the radiation detection devices overlap, thereby minimizing the area of the defect region generated in the long image. Can be

  Then, the image correcting unit 146 corrects the defective row in the defective area in which the image data 500 is overwritten before the image data 502 by using a normal row having a normal image area adjacent to the defective row. To do. The image correction unit 146 corrects the defective row by blending the image data of the normal row with the image data of the defective row while correlating with the image data of the defective row.

  The image correction unit 146 corrects defective rows using adjacent normal rows one by one. The corrected defective line becomes a new normal line and is used for correcting the next defective line. The correction is performed by repeating the process of correcting the defective line to the normal line one by one so that the entire defective area is processed. That is, the image correction unit 146 divides the defect area of the long image into defect lines in units of lines, and from the end line of the defect area to a normal line that is a part of the normal area adjacent to the end line or a corrected defect The correction process to approximate the pixel value distribution of the row is repeated for each row.

  For example, when correcting from the top to the bottom of the image, the defective row Y (1) is corrected using the normal row Y (0). The defective row Y (2) is corrected by setting the corrected defective row Y (1) as a normal row. Therefore, for 1 ≦ n ≦ N, the defective row Y (n) can be corrected sequentially with Y (n−1) as a normal row. When correction is performed from bottom to top, defective rows Y (n) are corrected sequentially from n = N with Y (n + 1) as a normal row.

The correction processing performed here may be any method as long as it utilizes the fact that there is a correlation between adjacent pixels. For example, the x-th (1 ≦ x ≦ W) of the row Y (n) of the long image is represented by coordinates (x, Y (n)), and the pixel value before correction at the coordinates is represented by I (x, Y (n )). The corrected pixel value is expressed by the following equation as O (x, Y (n)).
O (x, Y (n)) = f (I (x, Y (n)))
In the above equation, the function f is a function that minimizes the following equation.

上式においてＹ（ｍ）はＹ（ｎ）に隣接する正常行を表す。例えば関数ｆを多項式で表し、最小二乗法により多項式係数を求めることで行毎に欠陥行を正常行に変換する関数を得ることができる。この関数を用いて式１を計算することにより補正を行うことが可能になる。

In the above formula, Y (m) represents a normal row adjacent to Y (n). For example, the function f is represented by a polynomial, and a function for converting a defective row into a normal row for each row can be obtained by obtaining a polynomial coefficient by the least square method. Correction can be performed by calculating Equation 1 using this function.

Further, correction may be performed using structural data. A pixel value on the structure data corresponding to the coordinates (x, Y (n)) is P (x, Y (n)). It is assumed that the pixel value P (x, Y (n)) of the structure data has information regarding the structure of the radiation detection apparatus reflected in the pixel value I (x, Y (n)) of the long image. At this time, the corrected pixel value O (x, Y (n)) is expressed by the following equation.
O (x, Y (n)) = g (I (x, Y (n)), P (x, Y (n)))
In the above equation, the function g is a function that minimizes the following equation.

上式においてＹ（ｍ）はＹ（ｎ）に隣接する正常行を表す。例えば関数ｇを多項式で表し、最小二乗法により多項式係数を求めることで行毎に欠陥行を正常行に変換する関数を得ることができる。関数ｇは構造データの情報も用いて補正を行うためより良好な補正を行うことが可能になる。

In the above formula, Y (m) represents a normal row adjacent to Y (n). For example, the function g can be expressed by a polynomial, and a function for converting a defective row into a normal row for each row can be obtained by obtaining a polynomial coefficient by the least square method. Since the function g performs correction using also the information of the structure data, it is possible to perform better correction.

  Note that the image correction unit 146 may use only the correction result in one direction, but can also blend the correction results in the upper and lower directions. The image correction unit 146 corrects the long image by generating two correction results by performing bi-directional correction from the upper and lower adjacent rows sandwiching the defect area of the long image. For example, the image correction unit 146 generates two pieces of image data of the defective area corrected from the upper direction and two pieces of image data of the defective area corrected from the lower direction. The defective row corrected from the upper direction and the defective row corrected from the lower direction are the same row in the defect region (overlapping region). Specifically, the image correction unit 146 corrects the image data of the defective row by taking the average of the image data of the defective row corrected from above and the image data of the defective row corrected from below. In addition, since the corrected defect line is considered to have higher correction accuracy as it is closer to the normal line adjacent to the end of the defect area, the correction result is blended in consideration of the weight based on the distance from the correction start line. Also good. In this case, assuming that the number of rows in the defective area is N-1, the correction result from the upper direction is O1, and the correction result from the lower direction is O2, the correction result O (n) of the nth row is expressed by the following equation, for example. Can do.

階調処理部１４８は、複数の画像データ（放射線画像）を合成して、画像補正部１４６によって補正が行われた長尺画像に対して、階調処理を行なう。具体的には、階調処理部１４８は、放射線検出装置１２０、１２２、１２４から取得された複数の画像データを記憶部１４０から取得する。階調処理部１４８は、放射線検出装置１２０、１２２、１２４から取得された複数の画像データの特徴量をそれぞれ解析して、表示部１３２のダイナミックレンジを有効に利用することができるように、長尺画像の階調変換特性を決定する。

The gradation processing unit 148 combines a plurality of image data (radiation images) and performs gradation processing on the long image that has been corrected by the image correction unit 146. Specifically, the gradation processing unit 148 acquires a plurality of image data acquired from the radiation detection devices 120, 122, and 124 from the storage unit 140. The gradation processing unit 148 analyzes the feature amounts of the plurality of image data acquired from the radiation detection apparatuses 120, 122, and 124, respectively, so that the dynamic range of the display unit 132 can be used effectively. Determine the tone conversion characteristics of the scale image.

  Then, the gradation processing unit 148 converts the gradation of the long image using the determined gradation conversion characteristic. The feature amount includes a histogram of each image data, a maximum pixel value, and a minimum pixel value. By performing analysis processing on a plurality of image data acquired from the radiation detection devices 120, 122, and 124, the feature amount The amount is calculated.

  Since the gradation processing unit 148 performs gradation processing on the long image in which the defect area is reduced by the image correction unit 146, the gradation processing of the long image can be appropriately performed. That is, the gradation processing unit 148 can perform gradation processing of a long image while suppressing a defective area.

  FIG. 8 shows an image after gradation processing is performed by the gradation processing unit 148. Here, it is assumed that a plurality of structures 550 exist in the defect area of the long image.

  The mask processing unit 150 performs mask processing on the structure 550 that is reflected in the defect area of the long image after the gradation processing. Mask processing is performed on a structure having a low radiation transmittance that cannot be corrected by the image correction unit 146. The structure on which the mask processing unit 150 performs the mask processing is at least one of a fastener, a packing member, a buffer member, and a circuit in the radiation detection apparatus.

  The reason why the mask processing is performed after the gradation processing by the gradation processing unit 148 is to prevent the region masked by the mask processing unit 150 from being emphasized by the gradation processing.

  The mask processing unit 150 does not perform mask processing on the image data 500 because the image data 500 is a normal image region. On the other hand, the mask processing unit 150 performs mask processing on a structure located on the image data 502. The mask processing unit 150 performs mask processing on the structure 550 using pixel values around each structure 550. With respect to the mask processing method of the mask processing unit 150, an average pixel of pixel values around each structure 550 may be used, or noise such as white noise may be added to the average pixel value. Note that the mask processing unit 150 can be set not to perform mask processing on the structure 550 corresponding to the edge in the subject area.

  The mask processing unit 150 may determine the structure 550 to be masked by analyzing the image data 502. The mask processing unit 150 extracts the structure 550 by analyzing the pixel value in the defect area. Specifically, the mask processing unit 150 analyzes the histogram of the defect area in the long image, and extracts a region having a low pixel value and a predetermined area or more as the structure 550.

  Further, the mask processing unit 150 may acquire the image data 502 in advance before imaging the subject and specify and store the position and size of the structure in the image data 502. The mask processing unit 150 can specify the structure 550 to be masked from the position and size of the structure stored in advance.

  FIG. 9 shows a long image after the correction process and the mask process displayed on the display unit 132 are performed. By masking the long image with respect to the defect region (overlapping region), image defects due to the defect region in which the structure of the radiation detection apparatus is reflected can be reduced, and the image quality of the long image can be improved.

  The display unit 132 can display a long image with a reduced defect area. That is, it is possible to improve the image quality of the long image including the reflection of the structure of the radiation detection apparatus.

  Next, the operation procedure of the radiation imaging system will be described with reference to the flowchart of FIG.

  Step (S801): The operator places a plurality of radiation detection devices on the imaging table 110. The operator places the radiation detection devices 120, 122, and 124 on the imaging table 110 along the longitudinal direction of the imaging table 110. At this time, the operator arranges a plurality of radiation detection devices while overlapping a part of the radiation detection devices so that the effective pixel regions capable of detecting radiation overlap.

  Step (S802): The operator causes the plurality of radiation detection devices 120, 122, and 124 to perform imaging simultaneously, and simultaneously causes the plurality of radiation detection devices 120, 122, and 124 to send image data to the synthesis processing unit 142. Output. The composition processing unit 142 synthesizes the image data to generate a long image.

  Step (S803): The operator selects via the operation unit 134 whether or not to perform correction processing for reducing the defect area on the long image. For example, when the defect area where the reflection of the structure of the radiation detection apparatus appears is out of the diagnosis area, the correction process may not be performed. When the long image correction process is not performed, the process proceeds to step (S805). When the long image correction process is performed, the process proceeds to step (S804).

  Step (S804): The image correction unit 146 performs a process of correcting a defect area due to the reflection of the structures of the radiation detection device 120 and the radiation detection device 124 on the long image output from the synthesis processing unit 142. .

  Step (S805): The gradation processing unit 148 performs gradation processing on the long image output from the composition processing unit 142. Alternatively, the gradation processing unit 148 performs gradation processing on the long image that has been corrected by the image correction unit 146. A long image on which gradation processing has been performed is displayed on the display unit 132.

  Step (S806): The operator selects via the operation unit 134 whether to perform mask processing on the long image after gradation processing. The operator can make a judgment by observing the long image displayed on the display unit 132.

  For example, the gradation processing by the gradation processing unit 148 may cause the structure in the long image not to be anxious. If the operator does not care about the structure in the defect area due to the reflection of the structure, the operator may not perform the mask process. If mask processing is not performed, the process proceeds to the end.

  Further, the mask processing unit 150 may automatically select whether or not to perform mask processing. Specifically, the mask processing unit 150 analyzes the defect region in the long image after the gradation processing in the gradation processing unit 148, and the structure 550 has a region having a low pixel value and a predetermined area or more. In this case, the mask processing may be selected. When the long image mask process is performed, the process proceeds to step S807.

  Step (S807): The mask processing unit 150 performs mask processing on the structure remaining in the long image output from the gradation processing unit 148. The mask processing unit 150 performs mask processing on a structure having a low radiation transmittance that cannot be corrected by the image correction unit 146 in a defect region caused by reflection of the structure of the radiation detection device 120 and the radiation detection device 124. .

  As described above, according to the present embodiment, the radiation imaging system combines a plurality of radiation detection devices 120, 122, and 124 that detect radiation and a plurality of radiation images acquired from the plurality of radiation detection devices into a long image. Is generated. The radiation imaging system includes an image correction unit 146 that corrects a defect area of a long image on which the radiation detection apparatus is superimposed. In addition, the radiation imaging system includes a mask processing unit 150 that performs mask processing on the structure of the radiation detection apparatus in the defect region of the long image.

  The radiation imaging system also includes an image correction unit 146 that corrects a defect area of a long image so as not to be noticeable, and a mask processing unit 150 that performs a mask process on a structure of the radiation detection apparatus in the defect area of the long image. Are provided with two image processes. By executing with the image correction unit 146 that performs the processing of the defective area and the mask processing unit 150 that performs the local processing, it is possible to reliably reduce the structure from the long image. Thereby, the image quality of the long image including the defective area can be improved.

  Next, Example 2 will be described. The difference from the first embodiment is that the mask processing unit 150 applies the result of adjusting each image data to mask the structure in the region where the radiation detection device in the long image is superimposed.

  Specifically, the composition processing unit 142 generates a long image by adjusting the enlargement ratio of each image data according to the arrangement relationship of the radiation detection apparatuses.

  A plurality of radiation detection devices are arranged on the imaging table 110 while overlapping a part of the radiation detection devices, and the distance to the radiation generation unit 112 is different, so that the magnification rate of the subject on the image data differs. Specifically, the subject is enlarged and imaged on the image data acquired by the radiation detection device 122 far from the radiation generation unit 112 compared to the radiation detection device 120 and the radiation detection device 124. Therefore, the synthesis processing unit 142 enlarges the image data acquired by the radiation detection device 120 and the radiation detection device 124 in accordance with the image data acquired by the radiation detection device 122.

  The synthesis processing unit 142 may adjust the relative position of the image data acquired by the radiation detection device 120 and the radiation detection device 124 according to the image data acquired by the radiation detection device 122. Since it is difficult to strictly arrange the radiation detection apparatus on the imaging table so that the relative position is constant, a positional deviation of several millimeters may occur. Therefore, the synthesis processing unit 142 can perform alignment by combining the image data acquired and enlarged by the radiation detection device 120 and the radiation detection device 124 with the image data acquired by the radiation detection device 122. .

  Note that the synthesis processing unit 142 may rotate the image data acquired by the radiation detection device 120 and the radiation detection device 124 according to the image data acquired by the radiation detection device 122. This also corresponds to the positional deviation that occurs when the radiation detector is arranged on the imaging table.

  Then, the mask processing unit 150 applies the result of adjusting each image data to the structure in the defect area. The mask processing unit 150 performs a mask process on the structure of the defect area on which the radiation detection device in the long image is superimposed.

  Next, Example 3 will be described with reference to FIG. The difference from the first and second embodiments is that a defect area acquisition unit 144 that acquires a defect area in an area where the radiation detection apparatus is superimposed from image data is provided.

  The defect area acquisition unit 144 acquires a defect area indicating the structure (structure information) of the other radiation detection apparatus 120 and the radiation detection apparatus 124 from the image data (radiation image) acquired from the one radiation detection apparatus 122.

  Specifically, the defect area acquisition unit 144 acquires image data of the radiation detection apparatus 122 that does not include the image information of the subject 100 from the storage unit 140. The defect area acquisition unit 144 recognizes in which area of the image data acquired from the radiation detection apparatus 122 the structures of the radiation detection apparatus 120 and the radiation detection apparatus 124 are present. That is, the defect area acquisition unit 144 recognizes area information on the structures of the radiation detection apparatus 120 and the radiation detection apparatus 124. The region information of the structures of the radiation detection device 120 and the radiation detection device 124 includes position information in the image data. Then, the defect area acquisition unit 144 outputs the defect area to the image correction unit 146 and the mask processing unit 150 together with the position information.

  When the radiation detection device 120 and the radiation detection device 124 are arranged so as to overlap with a part of the radiation detection device 122, a defect area of the radiation detection device 122 is obtained from image data acquired from the radiation detection device 120 and the radiation detection device 124. To get. That is, the defect area acquisition unit 144 determines which radiation detection apparatus the defect area is acquired from, based on the arrangement relationship between the plurality of radiation detection apparatuses 120, 122, and 124. Here, the defect area acquisition unit 144 acquires a defect area of the radiation detection apparatus from image data acquired from a radiation detection apparatus arranged on a side farther from the radiation generation unit 112 than a certain radiation detection apparatus. In other words, the defect area acquisition unit 144 does not acquire the defect area of the radiation detection apparatus from the image data acquired from the radiation detection apparatus arranged closer to the radiation generation unit 112 than the certain radiation detection apparatus.

  The defective area acquisition unit 144 acquires a defective area from the image data 302 acquired from the radiation detection device 122. When a plurality of radiation detection devices 120, 122, 124 are arranged and photographed in the form as shown in FIG. 4, the radiation detection device 122 is disposed so as to overlap a part of the radiation detection device 120 and the radiation detection device 124. The Therefore, the image data acquired from the radiation detection device 122 includes structures of the radiation detection device 120 and the radiation detection device 124. The defect area acquisition unit 144 acquires defect areas of the radiation detection apparatus 120 and the radiation detection apparatus 124 from the image data acquired from the radiation detection apparatus 122.

  As illustrated in FIG. 11, the image correction unit 146 performs a process of reducing the defect areas of the radiation detection device 120 and the radiation detection device 124 on the long image output from the synthesis processing unit 142. That is, the image correction unit 146 corrects a defective area in which a part of the radiation detection apparatus (a structure of the radiation detection apparatus) is reflected.

  Specifically, the image correction unit 146 recognizes the defect regions of the structures of the radiation detection device 120 and the radiation detection device 124 output from the defect region acquisition unit 144, and applies the defect regions reflected in the composite image. To correct.

  The mask processing unit 150 recognizes the defect area of the structure of the radiation detection apparatus 120 and the radiation detection apparatus 124 output from the defect area acquisition unit 144, and masks the defect area structure reflected in the composite image. Process. The mask processing unit 150 masks the structure in the defect area from the image information around the structures of the radiation detection device 120 and the radiation detection device 124, and generates a long image. The image information around the structure of the radiation detection device 120 and the radiation detection device 124 is normal image information and image information that does not include the structure.

  Thereby, the image quality of the long image including the defective area can be improved.

DESCRIPTION OF SYMBOLS 100 Examinee 110 Imaging stand 112 Radiation generation part 114 Irradiation range 120 Radiation detection apparatus (D1)
122 Radiation detector (D2)
124 Radiation detector (D3)
DESCRIPTION OF SYMBOLS 130 Image display control part 132 Display part 134 Operation part 140 Storage part 142 Compositing process part 144 Defect area | region acquisition part 146 Image correction part 148 Tone processing part 150 Mask process part

Claims (10)

A plurality of radiation detection devices that detect radiation, and a synthesis processing unit that generates a long image by synthesizing a plurality of radiation images acquired from a plurality of radiation detection devices arranged to overlap a part of the radiation detection device When,
A radiation imaging system comprising: a mask processing unit configured to perform mask processing on a structure of the radiation detection device in a defect region of a long image generated by overlapping the radiation detection devices.   The radiation imaging system according to claim 1, wherein the area where the mask processing unit performs mask processing is a structure having a low radiation transmittance of the radiation detection apparatus.   The radiation imaging system according to claim 1, further comprising an image correction unit configured to correct the defect area so as not to be conspicuous with respect to the long image synthesized by the synthesis processing unit.   The radiation imaging system according to claim 3, further comprising a gradation processing unit that performs gradation processing on the long image in which the defect area is corrected by the image correction unit.   The radiation according to claim 4, wherein the mask processing unit performs mask processing on a structure that is reflected in a defect area of a long image after the gradation processing by the gradation processing unit. Shooting system.   The radiation imaging system according to claim 1, wherein the mask processing unit performs mask processing on the structure using pixel values around each structure.   The radiation imaging system according to claim 1, wherein the mask processing unit performs mask processing on the structure using an average pixel of pixel values around each structure.   The radiographic system according to claim 1, wherein the synthesis processing unit synthesizes a plurality of radiographic images so as to minimize an area of a defect region generated in the long image.   The radiation imaging system according to claim 1, wherein the structure on which the mask processing unit performs mask processing is at least one of a fastener, a packing member, a buffer member, and a circuit in the radiation detection apparatus.   In a radiography method for generating a long image by synthesizing a plurality of radiation images acquired from a plurality of radiation detection devices arranged by overlapping a part of the radiation detection device, in a region where the radiation detection devices are superimposed A radiation imaging method comprising performing mask processing on a structure of a radiation detection apparatus.

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