JP4612353B2 - X-ray stereoscopic equipment - Google Patents

Description

  The present invention relates to an X-ray stereoscopic apparatus that reconstructs a cross-sectional image or a stereoscopic image (multi-level cross-sectional image) from a plurality of X-ray images having different imaging directions.

  There is a technique called X-ray stereoscopic imaging or DT (Digital Tomosynthesis) as a technique for creating a cross-sectional image field stereoscopic image (cross-sectional image of a plurality of cross sections) using X-ray images taken from several directions. In the X-ray stereoscopic imaging method, a cross-sectional image is reconstructed from a plurality of X-ray images photographed from multiple directions (hereinafter referred to as “imaging” in order to distinguish it from the reconstruction of the X-ray CT). As an actual process, from a plurality of X-ray images taken from a plurality of directions, a plurality of rays passing through the points are selected for each point (pixel) on a specified cross section, and pixels corresponding to those rays are selected. Select and add values. By this processing, in principle, a portion on the designated cross section is clearly displayed, and a portion outside the cross section is blurred.

  In this X-ray stereoscopic imaging method, it is required to accurately specify the position of the X-ray tube and the position of the X-ray detector at the time of capturing each X-ray image. For this reason, in many cases, a pair of X-ray marker panels are placed at specified positions with the subject interposed therebetween, and the subject is photographed together with the X-ray marker panel. On the X-ray marker panel, a plurality of lead X-ray markers are arranged in a regular manner at regular intervals in the vertical and horizontal directions. The X-ray marker panel is imaged together with the subject, an X-ray marker image is extracted from the X-ray image in which both images are captured, and the X-ray tube and detector positions at the time of imaging are determined from the positional relationship of the X-ray markers. I'm calculating.

  However, the position calculation process using the X-ray marker panel has the following problem of lowering the position calculation accuracy. First, in the marker extraction process, a part of the subject, particularly a bent part of a blood vessel, may be erroneously extracted as an X-ray marker. The number of X-ray marker images that can be extracted is too small for accurate trajectory calculation processing.

  An object of the present invention is to improve the calculation accuracy of the position of the X-ray tube and the position of the X-ray detector in the X-ray stereoscopic imaging apparatus.

An X-ray stereoscopic imaging apparatus according to a first aspect of the present invention includes an X-ray tube, an X-ray detector, an image of a subject imaged by the X-ray tube and the X-ray detector, and the subject. Means for storing data of a plurality of X-ray images having different imaging directions each including an image relating to a plurality of markers whose mutual positional relationships are known in the vicinity of the specimen, and extracting the plurality of marker images from each of the X-ray images And a mis-extraction that identifies a mis-extracted marker image based on a mutual distance between the extracted marker images and removes the mis-extracted marker image from the extracted marker images Marker removing means, means for calculating the imaging position of the X-ray tube and the imaging position of the X-ray detector for each X-ray image from the positional relationship of the marker image remaining after the removal, and the calculated X The position of the tube and said Based on the position of the line detector, characterized by comprising a means for forming an image data of the cross-section or three-dimensional area from the data of the plurality of X-ray images.
An X-ray stereoscopic imaging apparatus according to a second aspect of the present invention includes an X-ray tube, an X-ray detector, an image of a subject imaged by the X-ray tube and the X-ray detector, and the subject. Means for storing data of a plurality of X-ray images having different imaging directions each including an image relating to a plurality of markers whose mutual positional relationships are known in the vicinity of the specimen; and firstly, the marker image from each of the X-ray images. Means for extracting by threshold value, means for estimating the imaging position of the X-ray tube and the imaging position of the X-ray detector for each X-ray image from the positional relationship of the extracted marker images, and the estimated Based on the position of the X-ray tube and the position of the X-ray detector, the means for calculating the position of the unextracted marker image for each X-ray image, and the calculated position of the unextracted marker image Means for setting a local region for each X-ray image; Means for extracting the marker image from each of the X-ray images limited to the set local region by a second threshold, and the marker image extracted by the first threshold and the second threshold Means for calculating the imaging position of the X-ray tube and the imaging position of the X-ray detector for each X-ray image from the positional relationship with the marker image extracted by the above, and the calculated position of the X-ray tube And means for forming image data of a cross-section or a three-dimensional region from the data of the plurality of X-ray images based on the position of the X-ray detector.
An X-ray stereoscopic imaging apparatus according to a third aspect of the present invention includes an X-ray tube, an X-ray detector, an image of a subject imaged by the X-ray tube and the X-ray detector, and the subject. Means for storing data of a plurality of X-ray images having different imaging directions each including an image relating to a plurality of markers whose mutual positional relationships are known in the vicinity of the specimen, and extracting the plurality of marker images from each of the X-ray images And a mis-extraction that identifies a mis-extracted marker image based on a mutual distance between the extracted marker images and removes the mis-extracted marker image from the extracted marker images Marker removal means, means for estimating the imaging position of the X-ray tube and the imaging position of the X-ray detector for each X-ray image from the positional relationship between the marker images remaining after the removal, and the estimated X The position of the tube and said Based on the position of the line detector, a means for calculating the position of the unextracted marker image for each X-ray image, and a local area including the calculated position of the unextracted marker image for each X-ray image. Means for setting, means for extracting the marker image from each of the X-ray images limited to the set local region by a second threshold value, a marker image extracted by the first threshold value, and the Means for calculating the imaging position of the X-ray tube and the imaging position of the X-ray detector for each X-ray image from the positional relationship with the marker image extracted by the second threshold; And means for forming image data of a cross-section or a three-dimensional region from the data of the plurality of X-ray images based on the position of the tube and the position of the X-ray detector.

  According to the present invention, in the X-ray stereoscopic imaging apparatus, the calculation accuracy of the position of the X-ray tube and the position of the X-ray detector can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The outline of the present embodiment will be described. Since the positional relationship of the X-ray markers is known in advance as the erroneous extraction X-ray marker removal processing, the X-ray marker image by erroneous extraction is determined from the positional relationship of the extracted X-ray marker images. X-ray marker position coordinates of the corrected X-ray marker position coordinates obtained after the erroneous extraction X-ray marker removal process are used as a process for digging up the X-ray marker image that could not be extracted in the first extraction process. The minimum number of X-ray markers required to count the number and to ensure a certain level of X-ray tube and X-ray detector position calculation accuracy (orbit calculation accuracy of the X-ray tube and X-ray detector) When the image is not extracted, it is limited to the surrounding local region including the position of the X-ray marker image which can be estimated from the trajectory of the X-ray tube or the X-ray detector which can be roughly estimated from the extracted X-ray marker image. Then re High precision and performs X-ray marker image extraction processing.

  As a result, the position coordinates of the erroneously extracted X-ray marker can be automatically removed, and it is possible to greatly reduce the redo of the marker extraction process and manual correction work. In addition, since the extraction process is performed by limiting the region where the X-ray marker will appear in the X-ray image, more X-ray markers can be accurately extracted at the same time as the erroneous extraction is reduced. As described above, a cross-sectional image can be obtained more quickly and accurately than in the past.

  As shown in FIGS. 1 and 2, the X-ray stereoscopic imaging apparatus according to the present embodiment includes an X-ray tube apparatus 1 and an X-ray detector apparatus 7. The X-ray tube device 1 includes an X-ray tube 3 that generates X-rays upon receiving application of a high voltage (tube voltage) and supply of a filament current from a high voltage generator 20. The X-ray tube 3 is installed on a pedestal 6 with casters 5 via a rotation mechanism 4. The rotation mechanism 4 rotatably supports the X-ray tube 3 around the imaging center axis CA and rotates the X-ray tube 3 under the control of the rotation control unit 21. The X-ray tube 3 and the rotation mechanism 4 are accommodated in the housing 2. The X-ray detector device 7 has an X-ray detector 9. The X-ray detector 9 is typically a flat panel detector (also called a flat panel detector). The flat panel detector is a direct conversion type that directly converts incident X-rays into electrical signals, or an indirect conversion type that converts incident X-rays into light with a phosphor and converts the light into electrical signals. It has an element. The plurality of semiconductor detection elements are arranged in a two-dimensional lattice pattern. Signal charges generated by X-ray incidence by a plurality of semiconductor detection elements are read out as digital signals via the data acquisition unit 23. The X-ray detector 9 is installed on a pedestal 11 with a caster 12 via a rotation mechanism 10. The rotation mechanism 10 supports the X-ray detector 9 so as to be rotatable around the imaging center axis CA and rotates the X-ray detector 9 under the control of the rotation control unit 22. The X-ray detector 9 and the rotation mechanism 114 are accommodated inside the housing 8.

  At the time of imaging, the X-ray tube device 1 and the X-ray detector device 7 are placed so as to face each other with the subject P interposed therebetween, and the imaging center axes CA substantially coincide. The subject P is fixed on the top plate 14 of the bed 13 using the localization device 17. A pair of X-ray marker panels 15 and 16 are accurately placed in parallel with a predetermined distance across the subject P. As shown in FIG. 3A, one X-ray marker panel 15 includes a panel base 33 made of, for example, a transparent acrylic resin having a relatively low X-ray absorption rate, and a center point between the panel base 33 and a certain center point. For example, a lead X-ray marker 31 made of lead and having a high X-ray absorption rate arranged accurately at a distance da. As shown in FIG. 3B, the other X-ray marker panel 16 includes a panel base 34 made of, for example, a transparent acrylic resin having a relatively low X-ray absorption rate, and a center point between the panel base 34 and a certain center point. It consists of a cylindrical X-ray marker 32 made of, for example, lead and having a high X-ray absorption rate that is accurately arranged at a distance db. The reason why the X-ray marker 31 is a spherical shape and the X-ray marker 32 is a cylindrical shape is for the purpose of distinguishing both images by shape. As long as the purpose is achieved, the shape is spherical. It is not limited to a cylindrical shape.

  The system control unit 24 is responsible for operation control of the entire X-ray stereoscopic apparatus, and includes the image processing unit 25, the display unit 26, the mouse together with the high voltage generator 20, the data collection unit 23, and the rotation control units 21 and 22. And an operation unit 27 such as a keyboard via a data / control bus 28.

  Based on the positional relationship between the images of the X-ray markers 31 and 32 reflected in the X-ray image, the image processing unit 25 determines the position of the X-ray tube 3 and the X-ray detector 9 when the X-ray image is captured. While obtaining the position, a cross-sectional image is formed from a plurality of X-ray images having different imaging directions. As shown in FIG. 4, the image processing unit 25 includes a control unit 41, a logarithmic calculation unit 42, a position calculation unit 43, an imaging unit 44, a threshold setting unit 45, an interface 46, an image storage unit 47, and a marker extraction unit. 48, an erroneous extraction marker removal processing unit 49, a trajectory calculation unit 50, a marker search region setting unit 51, and a data / control bus 52. The image storage unit 47 stores data of a plurality of X-ray images output from the X-ray detector 9 via the data collection unit 23 and subjected to logarithmic calculation by the logarithmic calculation unit 42. The X-ray image includes images of the plurality of markers 31 and 32 together with the image of the subject. The marker extraction unit 48 extracts the image areas of the markers 31 and 32 for each X-ray image by threshold processing and pattern matching processing set by the threshold setting unit 45. A shadow having a luminance approximate to the image of the markers 31 and 32 and having a shape approximate to the image of the markers 31 and 32 is erroneously extracted as an image of the markers 31 and 32. The erroneous extraction marker removal processing unit 49 identifies the marker image erroneously extracted by the marker extraction unit 48 based on the mutual distance between the images of the plurality of markers 31 and 32 extracted by the marker extraction unit 48 and performs erroneous extraction. The marker image thus removed is removed from the plurality of marker images extracted by the marker extraction unit 48. The position calculation unit 43 removes the mis-extracted marker image, and from the images of the plurality of markers 31 and 32, the position of the X-ray tube 3 (X-ray focal position) and X The position of the line detector 29 (the position of the center of the X-ray detection surface) is calculated. The trajectory calculation unit 50 calculates the trajectory of the X-ray tube 3 connecting the imaging positions of the X-ray tube 3 corresponding to each image, and the X-ray detector connecting the imaging positions of the X-ray detector 29 corresponding to each image. Calculate 9 orbits. The marker search region setting unit 51 is based on the imaging position on the trajectory of the X-ray tube 3 calculated by the trajectory calculation unit 50 and the imaging position on the trajectory of the X-ray detector 9. And a circular local area having a predetermined radius centered on the positions of unextracted markers 31 and 32 is set as a marker search area. The marker extraction unit 48 markers the images of the markers 31 and 32 by threshold processing and pattern matching processing using threshold values set from the pixel value distribution in the marker search region (local region) by the threshold setting unit 45. Search and extract limited to the search area. The imaging unit 44 selects a cross-sectional image of an arbitrary cross section or a cross-sectional image of a multi-section (three-dimensional image) from a plurality of X-ray images based on the X-ray tube 3 imaging position and the X-ray detector 9 imaging position of each X-ray image. Image volume data).

  FIG. 5 shows a flow of the imaging process of the cross-sectional image according to the present embodiment. First, X-ray stereoscopic imaging is performed. For this purpose, the X-ray tube 3 and the X-ray detector 9 are disposed so as to face each other with the subject P and the marker panels 15 and 16 therebetween, and the imaging center axes substantially coincide. The subject P is fixed on the top plate 14 of the bed 13 using the localization device 17. A pair of X-ray marker panels 15 and 16 are accurately placed in parallel with a predetermined distance across the subject P. While the X-ray tube 3 and the X-ray detector 9 move along the circular orbit illustrated in FIGS. 6 and 7, X-ray imaging is repeated intermittently. Thereby, a plurality of X-ray images in which the imaging position of the X-ray tube 3 and the imaging position of the X-ray detector 9 are different are generated.

  In step S1, a plurality of X-ray images (see FIG. 9) are individually subjected to marker extraction processing by the marker extraction unit 48, and the coordinates of the center of gravity are calculated (see FIG. 10). In the marker extraction process, high-pass filter processing is performed on each X-ray image, and then the image areas of the markers 31 and 32 are extracted using a hysteresis threshold. The hysteresis threshold is a pixel value equal to or higher than the second two threshold values in each connected region of the regions having pixel values equal to or higher than the first threshold value using the first and second threshold values. This is processing for extracting at least one area. Next, for each connected region, only the region suitable for the image region of the marker 31 and the image region of the marker 32 is selected based on the circularity, the squareness, and the area. In this process, the image area of the marker 31 and the image area of the marker 32 are selected based on different criteria.

  The first and second threshold values are set for each X-ray image by the threshold setting unit 45 based on the pixel value distribution. The pixel value distribution is a distribution that represents the properties of an X-ray image with the horizontal axis representing the pixel value and the vertical axis representing the number of pixels (frequency). From this pixel value distribution, the first threshold value corresponds to a high X-ray absorption rate so that a lead image can be extracted effectively, such as an average value of pixel values from a high level to a predetermined rate (for example, the top 5%). A value designated in advance from the statistical index is set by the threshold value setting unit 45. Similarly, the second threshold value is higher than the first threshold value, for example, from a higher level to a predetermined ratio (for example, upper 3%) A threshold value setting unit 45 sets a value designated in advance from a statistical index such as an average value. The X-ray image is binarized with the threshold set by the threshold setting unit 45, and circular and square regions corresponding to the markers 31 and 32 are extracted by pattern matching processing. At the stage of the first marker extraction process, the images of the markers 31 and 32 are correctly extracted and images of other parts such as blood vessels other than the markers 31 and 32 are used. There are images that have been erroneously extracted and images of unextracted markers 31 and 32. In the present embodiment, the erroneously extracted image is removed, and the images of the unextracted markers 31 and 32 are extracted.

  The removal process (S2) of the erroneously extracted image by the erroneous extraction marker removal processing unit 49 will be described. As shown in FIG. 11A, during the extraction processing of the markers 31 and 32, a part of the subject and others may be mistakenly extracted as the images of the markers 31 and 32. Therefore, the position coordinates of the obtained marker image May include position coordinates due to erroneous extraction. In order to perform accurate X-ray focal point / detection surface trajectory estimation calculation, it is necessary to remove position coordinates due to erroneous extraction. For this purpose, an arithmetic process using the arrangement position of the X-ray marker panel and the distance between adjacent X-ray markers 31 and 32 on the X-ray marker panels 15 and 16 is performed on the obtained position coordinates. As for the arrangement positions of the X-ray marker panels 15 and 16, L, a, and b in FIG. 8 are used, and da and db are used as the distance between the adjacent X-ray markers 31 and 32 in the X-ray markers 31 and 32. . From these values, the distance between the X-ray markers 31 and 32 in the X-ray image is obtained, and it is determined whether the distance between the marker images obtained by the extraction processing matches this distance. It is possible to remove position coordinates by extraction.

  For example, when the position coordinates of the images of the X-ray markers 31 and 32 including erroneous extraction are obtained as shown in FIG. 11A, the position coordinates due to erroneous extraction are obtained by the following procedures 1) to 5). Remove.

1) Calculation of distance between X-ray marker image position coordinates
The distance between the position coordinates of the specific point and the position coordinates of all the other X-ray marker images is calculated using one extracted X-ray marker image having a plurality of marker images as the specific point. In the example of FIG. 11A, first, the coordinate 1 is set as a specific point, and six distances between the coordinate 1 and each of the coordinates 2 to 7 are obtained. Next, the specific point is moved to coordinate 2, and six distances between coordinate 2 and coordinates 1, 3 to 7 are obtained. The same distance calculation is repeated while moving the specific point to the coordinates 3 to 7 in order. For all X-ray marker image position coordinates, the distances from the other six X-ray marker image position coordinates are obtained.

2) Correctness of distance
It is determined whether the distance between the position coordinates obtained in the procedure 1) is a correct distance between X-ray marker images. For the determination, it can be used that the distance between correct X-ray marker position coordinates takes only a constant value. In the example of FIG. 11 (a), there are only five possible distance values shown in FIG. 12, and if the X-ray marker image position coordinates are correct, they should match any one of the five distance values. It is. The values of the distances from the other six position coordinates obtained for the respective X-ray marker image position coordinates are compared with five possible distance values, and correct / incorrect is determined. At this time, the determination may be made in consideration of an error of several percent. As a result of the determination, for each X-ray marker image position coordinate, the number of values determined to be correct and the number of values determined to be incorrect are known for the distance value from the other six position coordinates. Here, the distance D in FIG. 12 is a distance between adjacent correct X-ray marker image position coordinates on the detector surface. For example, when the X-ray marker panels 15 and 16 in which the X-ray markers 31 and 32 are arranged at the interval da are installed at the distance a from the tube 3 and the detector surface is located at a distance L from the tube,
D = da × L / a
It becomes.

3) X-ray marker image position coordinate removal
As a result of the determination in the above procedure 2), the X-ray marker image position coordinates having the highest chance (number of times) determined to be an error are regarded as position coordinates due to erroneous extraction and are removed. When the determination result as shown in FIG. 13 is obtained, the position coordinate 3 is removed as an erroneously extracted image. If there are a plurality of position coordinates corresponding to the removal, one of them is removed.

4) Iterative processing
Steps 1) to 3) are repeated after removing the X-ray marker image position coordinates having the largest distance value determined to be erroneous. The end condition is that all the distance values from other marker images are determined to be correct for all X-ray marker images. In the example of FIG. 13, as a result of the second process, a result as shown in FIG. 14 is obtained, the position coordinate 6 is removed, and the process is repeated again. As a result of the third process, the result of FIG. 15 is obtained, and the process ends. In this way, two X-ray marker image position coordinates due to erroneous extraction can be removed.

  Next, an image extraction process of unextracted markers 31 and 32 will be described. The X-ray marker image position coordinate data obtained after the marker extraction process and the erroneously extracted X-ray marker image position coordinate removal process includes the X-ray image number, the number of extracted X-ray marker images, and the extracted X-ray markers. The position coordinates of each image are included, and the position coordinates are in a state where one of the X-ray marker images 31 and 32 installed at two locations can be distinguished. By performing trajectory estimation calculation processing using the X-ray marker image position coordinate data, the position coordinates of the X-ray focal point / detection surface corresponding to each X-ray image are obtained. In order to perform accurate trajectory estimation calculation, the minimum necessary X-ray marker image position coordinates are necessary. Therefore, if the minimum number of extracted X-ray marker images is Nlim, an X-ray image in which the number of X-ray marker images extracted from each X-ray image is less than Nlim with reference to the X-ray marker image position coordinate data. Is confirmed by the control unit 41 (S3). Then, the following conditional branch is performed.

  When the number of extracted X-ray marker images is larger than Nlim in all X-ray images, the trajectory calculation calculation process is performed by the trajectory calculation unit 50 as in the conventional processing flow (S4), and image reconnection is performed. Image processing is performed (S5).

  If there is at least one X-ray image whose number of extracted X-ray marker images is smaller than Nlim, the number of the X-ray image that does not satisfy the condition is stored as a reprocessed X-ray image number, and the number is small The trajectories of the X-ray tube 3 and the X-ray detector 9 are estimated with the X-ray marker image (S6), and the position where the X-ray marker image will appear on the X-ray image from the trajectory is set as the marker search region. Predicted by the unit 51 (S7). The X-ray marker image position prediction calculation process is performed as follows.

The position coordinates of the X-ray focal point / detection surface corresponding to each X-ray image obtained by the trajectory estimation calculation process, L, a, b, c in FIG. 8, and X-ray marker panels 15 and 16 in FIG. X-ray marker placement coordinates
(x ^a _i , y ^a _j ) (i = 1, 2,... N1, j = 1, 2,... N2)
(x ^b _i , y ^b _j ) (i = 1, 2,... M1, j = 1, 2,... M2)
It is possible to determine at which position in the X-ray image the X-ray marker image passes. Here, the X-ray marker arrangement coordinates are coordinates with the center of the X-ray marker panel 15 or 16 as the origin. From these values, it is possible to determine the coordinates on the image of the X-ray focal point, the detector detection surface, and the X-ray markers 31 and 32 in the imaging coordinate system having the origin at the center of the subject imaging region as shown in FIG. it can.

In FIG. 16, (x ^f _l , y ^f _l , z ^f _l ) are the coordinates of the X-ray focal point, and (x ^d _l , y ^d _l , z ^d _l ) are the coordinates of the center of the detection surface. The subscript l is l = 1, 2,..., Lmax, with the number of X-ray images taken as lmax as the upper limit. Further, the individual X-ray marker x, y _{^{coordinates, (x a i, y a}} j) (i = 1,2, ··· N1, j = 1,2, ··· N2), (x b _i , y ^b _j ) (i = 1, 2,... M1, j = 1, 2,... M2).

Extracting X-ray X-ray focal-detection surface center of the coordinates when the number of markers image is captured X-ray image the missing ^{_{(x f l, y f l}} , z f l), (x d l, y d _l , z ^d _l ), the X-ray marker is the x, y coordinates on the detection surface

It can be calculated to be reflected in each. In practice, depending on the size of the detection surface, there are images of the X-ray markers 31 and 32 that do not appear, so it is only necessary to obtain the X-ray markers that are visible. The coordinates thus obtained are stored as predicted X-ray marker image position coordinates on the detection surface.

  Assuming that the position coordinates of the X-ray marker image predicted from the trajectory are obtained as indicated by a cross in the X-ray image as shown in FIG. The marker search area setting unit 51 sets (S8).

  The threshold setting unit 45 is set for each local region based on the pixel value distribution in that region. From the pixel value distribution, the first threshold value is set by the threshold value setting unit 45 to a value specified in advance from a statistical index such as an average value of pixel values from a high level to a predetermined ratio (for example, the top 20%), Similarly, the second threshold value is higher than the first threshold value, for example, a value specified in advance from a statistical index such as an average value of pixel values from a high level to a predetermined ratio (for example, the top 15%) Set by the unit 45 (S9). Returning to S1, similarly, the local area is binarized with the threshold set by the threshold setting unit 45, and circular and square areas corresponding to the markers 31 and 32 are extracted by pattern matching processing. The shape of the local search area is not limited to a square, and may be a circle. The processing is continued using the position coordinates of the X-ray marker image extracted in this way as X-ray marker image position coordinate data. By the above process, an X-ray marker image can be more reliably extracted from an X-ray image, and an accurate trajectory estimation calculation process can be performed.

  As described above, according to the present embodiment, erroneous marker extraction can be removed, and unextracted marker images can be re-extracted. Therefore, the position of the X-ray tube and X-ray detection can be detected from these marker images. The position of the vessel can be calculated with high accuracy. Thereby, the imaging accuracy of a cross-sectional image or volume data can be improved.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The figure which shows the structure of the principal part of the X-ray stereoscopic imaging apparatus which concerns on embodiment of this invention. The figure which shows the external appearance of the X-ray tube apparatus and X-ray detector apparatus of FIG. The top view of the X-ray marker panel of FIG. The figure which shows the structure of the image processing figure of FIG. The figure which shows the flow of the imaging process of a cross-sectional image in this embodiment. The figure which shows the rotation orbit of the X-ray tube and X-ray detector at the time of imaging | photography in this embodiment. FIG. 4 is a diagram illustrating a photographing region where an image can be formed in the present embodiment. The figure which shows the positional relationship of an X-ray tube, a detector, etc. in this embodiment. In the present embodiment, a halftone image showing an example of an X-ray image. The figure which shows the relationship between an X-ray marker and a marker image in this embodiment. The figure which shows the marker image mis-extracted in this embodiment. The figure which shows the mutual distance between marker images in this embodiment. The figure which shows an example of the errata table of the mutual distance between the marker images at the time of the 1st mistake extraction determination in this embodiment. The figure which shows an example of the errata of the mutual distance between the marker images at the time of the 2nd mistake extraction determination in this embodiment. In this embodiment, the figure which shows an example of the errata of the mutual distance between the marker images at the time of the 3rd (the last example in this example) misextraction determination. The supplementary figure of the position prediction process of an unextracted marker image in this embodiment. The figure which shows the search area | region of the marker image containing the position of the predicted marker image in this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... X-ray tube apparatus, 2 ... X-ray generator housing, 3 ... X-ray tube, 4 ... X-ray tube rotation mechanism, 5 ... Caster, 6 ... Base, 7 ... X-ray detector apparatus, 8 ... Housing , 9 ... X-ray detector, 10 ... X-ray detector rotation mechanism, 11 ... Pedestal, 12 ... Caster, 13 ... Couch, 14 ... Top plate, 15 ... X-ray marker panel, 16 ... X-ray marker panel, 17 ... Localization device, 20 ... high voltage generator, 21 ... X-ray tube rotation control unit, 22 ... X-ray detector rotation control unit, 23 ... data collection unit, 24 ... system control unit, 25 ... image processing unit, 26 ... display Part, 27 ... operation part.

Claims (5)

An X-ray tube;
An X-ray detector;
A plurality of different imaging directions each including an image relating to the subject and images relating to a plurality of markers whose mutual positional relationships are known in the vicinity of the subject, which are taken by the X-ray tube and the X-ray detector. Means for storing X-ray image data of
Means for extracting the plurality of marker images from each of the X-ray images;
A mis-extracted marker removing unit that identifies a mis-extracted marker image based on a mutual distance between the extracted marker images and removes the mis-extracted marker image from the extracted marker images; ,
Means for calculating, for each X-ray image, the imaging position of the X-ray tube and the imaging position of the X-ray detector from the positional relationship of the marker image remaining after the removal;
Means for imaging image data of a cross-section or a three-dimensional region from the data of the plurality of X-ray images based on the calculated position of the X-ray tube and the position of the X-ray detector. X-ray stereoscopic imaging apparatus. The erroneous extraction marker removal means includes means for calculating a mutual distance between the extracted marker images, a means for determining whether the calculated mutual distance is correct, and a mutual distance between the other marker images is an error. Means for removing the marker image with the largest number of determinations as the erroneously extracted marker image, calculation of the mutual distance until the erroneous determination does not occur, determination of the correctness and removal of the erroneously extracted marker image The X-ray stereoscopic imaging apparatus according to claim 1, further comprising: means for repeating the series of processes. An X-ray tube;
An X-ray detector;
A plurality of images with different imaging directions each including an image relating to the subject and images relating to a plurality of markers whose mutual positional relationships are known in the vicinity of the subject, taken by the X-ray tube and the X-ray detector. Means for storing X-ray image data;
Means for extracting the marker image from each of the X-ray images by a first threshold;
Means for estimating the imaging position of the X-ray tube and the imaging position of the X-ray detector for each X-ray image from the positional relationship of the extracted marker images;
Means for calculating the position of an unextracted marker image for each X-ray image based on the estimated position of the X-ray tube and the position of the X-ray detector;
Means for setting a local region including the calculated position of the unextracted marker image for each X-ray image;
Means for extracting the marker image from each of the X-ray images limited to the set local region by a second threshold value;
Based on the positional relationship between the marker image extracted by the first threshold and the marker image extracted by the second threshold, the imaging position of the X-ray tube and the imaging position of the X-ray detector are determined as X Means for calculating each line image;
Means for imaging image data of a cross-section or a three-dimensional region from the data of the plurality of X-ray images based on the calculated position of the X-ray tube and the position of the X-ray detector. X-ray stereoscopic imaging apparatus. The first threshold value is set for each X-ray image from the pixel value distribution of each of the X-ray images, and the second threshold value is set for each of the local areas from the pixel value distribution of each of the local regions. The X-ray stereoscopic imaging apparatus according to claim 3, further comprising means. An X-ray tube;
An X-ray detector;
A plurality of images with different imaging directions each including an image relating to the subject and images relating to a plurality of markers whose mutual positional relationships are known in the vicinity of the subject, taken by the X-ray tube and the X-ray detector. Means for storing X-ray image data;
Means for extracting the plurality of marker images from each of the X-ray images;
A mis-extracted marker removing unit that identifies a mis-extracted marker image based on a mutual distance between the extracted marker images and removes the mis-extracted marker image from the extracted marker images; ,
Means for estimating the imaging position of the X-ray tube and the imaging position of the X-ray detector for each X-ray image from the positional relationship of the marker image remaining after the removal;
Means for calculating the position of an unextracted marker image for each X-ray image based on the estimated position of the X-ray tube and the position of the X-ray detector;
Means for setting a local region including the calculated position of the unextracted marker image for each X-ray image;
Means for extracting the marker image from each of the X-ray images limited to the set local region by a second threshold value;
Based on the positional relationship between the marker image extracted by the first threshold and the marker image extracted by the second threshold, the imaging position of the X-ray tube and the imaging position of the X-ray detector are determined as X Means for calculating each line image;
Means for imaging image data of a cross-section or a three-dimensional region from the data of the plurality of X-ray images based on the calculated position of the X-ray tube and the position of the X-ray detector. X-ray stereoscopic imaging apparatus.

Images