JP4467522B2 - Tomographic image constructing apparatus and method - Google Patents

Description

  The present invention relates to a tomographic image forming apparatus and method for forming a tomographic image from as few as two X-ray images.

  The tomographic image of the subject is usually captured using a tomographic image generation apparatus such as an X-ray CT apparatus. In recent years, for example, two X-ray images taken with low X-ray exposure using an X-ray imaging apparatus most widely used in medical facilities, and the tomographic image of the subject and There is a demand to construct a three-dimensional image from a tomogram.

  The technique of image composition using the above two X-ray images is “IEEE TRANSACTIONS ON MEDICAL IMAGING, VOL. 22, NO. 6, JUNE 2003”, 710-721, “Kinematic and Deformation Analysis of 4-D Coronary Arterial. There is a method described in “Trees Reconstructed From Cine Angiograms” (referred to as “conventional method”). This conventional method calculates the center line of a dendritic blood vessel that travels to the heart by projection from orthogonal X-ray images, and information on the thickness of the blood vessels projected from each X-ray image along the calculated center line Is added to construct a three-dimensional image.

  However, since the conventional method is limited to the configuration of a three-dimensional image using two X-ray images that are orthogonal to each other, two X-ray images arranged at arbitrary different angles are back-projected. There is no mention of constructing a tomographic image.

The tomographic image construction apparatus of the present invention is a binarized image creating means for binarizing each of the X-ray images from a plurality of different directions of the subject imaged by the X-ray device to create a plurality of binarized images, A scanning line setting unit that sets scanning lines that sequentially move in predetermined directions to positions corresponding to each other of the plurality of binarized images created by the binarized image creating unit, and set by the scanning line setting unit A tomographic image forming unit configured to form a tomographic image by back projecting pixel points of the plurality of binarized images at a position where the scanning line sequentially moves, and the scanning line setting unit includes a two-dimensional scanning line Scan line direction setting means for calculating the appearance frequency of the run length for the direction and setting one of the two-dimensional scan line directions based on the calculated appearance frequency is included.

  Thus, considering to reduce X-ray exposure to the subject, a tomographic image of the subject can be obtained using a smaller number of X-ray images, that is, two X-ray images. The X-ray image here includes a digital image taken using a flat detector or the like, or an image obtained by digitizing a film image. Further, the smaller number than the above may be three or more X-ray images. In this case, although the effect of reducing the X-ray exposure is reduced, the accuracy of the resulting tomographic image is improved.

  Also, according to a preferred embodiment of the present invention, the scanning line setting means calculates a tomographic image in each of the tomographic images formed by the tomographic image forming means in a direction opposite to the forward direction of the scanning line. A false area detecting unit for detecting a false area based on the correlation; and a false area deleting unit for deleting the false area detected by the false area detecting unit.

  As a result, the false region is deleted based on the correlation between the tomographic image in which the scanning line movement direction is the positive direction and the tomographic image in which the scanning line movement direction is the reverse direction. An image is obtained. If an area where the correlation is less than a predetermined value is detected, the area is a false area, so that the false area can be efficiently deleted.

  Also, according to a preferred embodiment of the present invention, the scanning line setting means is either one of a position where a pixel value takes a predetermined value on the scanning line and a position designated by an operator. Is set as the initial position of the scanning line.

  As a result, the initial position of the scanning line can be arbitrarily set, so if it is set in the vicinity of the region to be extracted, the binarized region for constructing the tomographic image can be moved more efficiently. As a result, the computation for constructing the tomographic image can be speeded up.

  Also, according to a preferred embodiment of the present invention, the tomographic image constructing device comprises a plurality of adjacent tomographic images formed by the tomographic image forming means, and a predetermined rendering method from the plurality of configured tomographic images. 3D image constructing means for constructing a 3D image, and image display means for displaying the 3D image constructed by the 3D image constructing means.

  According to this, it is possible to easily grasp the shape of the subject by constructing a three-dimensional image from the tomographic image.

The tomographic image constructing method of the present invention includes a binarized image creating step of binarizing each of the X-ray images from a plurality of different directions of the subject imaged by the X-ray device to create a plurality of binarized images, A scanning line setting step for setting scanning lines that sequentially move in predetermined directions to positions corresponding to each other of the plurality of binarized images created by the binarized image creating step, and the scanning line setting step A tomographic image forming step of forming a tomographic image by back projecting pixel points of the plurality of binarized images at positions where the scanning line sequentially moves, and the scanning line setting step includes a two-dimensional scanning line A scan line direction setting step of calculating a run length appearance frequency for the direction and setting one of the two-dimensional scan line directions based on the calculated appearance frequency is included.

  Thus, considering to reduce X-ray exposure to the subject, a tomographic image of the subject can be obtained using a smaller number of X-ray images, that is, two X-ray images.

  Hereinafter, preferred embodiments of a tomographic image constructing apparatus and method using X-ray images according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a configuration of a tomographic image forming apparatus 10 according to the present embodiment. The tomographic image forming apparatus 10 includes a central processing unit (hereinafter referred to as CPU) 11, a main memory 12, a magnetic disk 13, a display memory 14, a CRT 15, a controller 16, a mouse 17, and a keyboard 18, and these are a common bus 19. It is electrically connected via.

  The main memory 12 is used as an area for temporary storage and processing of images and data, and processing results are displayed on the CRT 15 via the display memory 14 and stored in the magnetic disk 13 for redisplay and result reference. . An X-ray image is stored on the magnetic disk 13. The X-ray image can also be acquired from the X-ray apparatus 1B connected via the LAN 1A. The X-ray apparatus 1B includes all apparatuses capable of capturing all X-ray images, such as an X-ray fluoroscopic table and a digital radiography apparatus. The X-ray image includes a digital image taken using a flat detector or the like, and an image obtained by digitizing a film image.

(First embodiment)
Next, tomographic image construction processing will be described with reference to the flowchart of FIG. Here, a case where a tomographic image is constructed from two X-ray images will be described. These X-ray images 31, 32, the tomographic image 33, and the three-dimensional image 34 have the positional relationship shown in FIG. The tomographic image 33 is formed by binarizing the X-ray images 31 and 32 and partially projecting the binarized X-ray images 31 and 32, and the three-dimensional image 34 is generated from the tomographic image 33 using a rendering algorithm. Configure.

(Step 20)
As shown in FIG. 4, the X-ray image 31 captured by the X-ray source 41 is subjected to binarization processing in which the target organ a, the other organs b and c are 1, and the other regions are 0. Similarly, the X-ray image 32 taken by the X-ray source 42 is subjected to binarization processing in which the target organ a, the other organs b and c are set to 1, and the other regions are set to 0. A projection center 51 and a projection center 52 are arranged at the position of the X-ray source where these two X-ray images are taken, respectively. When the area surrounded by the projection line from the projection center is stored in the memory, it is as shown in FIG. That is, the target organ a and the regions b and c (referred to as “false regions”) other than the target organ are stored in the memory in a state where they cannot be distinguished from each other. However, as shown in FIG. 6, no false region appears at the projection center 61 and the projection center 62 from each X-ray image obtained by photographing only one target organ. That is, only the target organ a is stored in the memory.

  Therefore, in the tomographic image constructing apparatus 10, in order to search for a target organ first using this property, for example, the straight line of number 1 in FIG. Projection processing is performed, and the processing proceeds to adjacent 2,3,... Or 2 ′, 3 ′,. In the second and subsequent back projections, selection is performed based on continuity with adjacent areas. For example, it is assumed that a blood vessel that disappears on the way like the region 71 or 72 in FIG. 7A is not extracted.

  The binarization processing here is generally based on threshold processing, but may be manually traced to set the inside of the target organ to 1 and the outside to 0. In this example, one area on the one-line value in the X direction of the image is searched. As shown in FIG. 8, an area 81 having the maximum run length (the number of consecutive pixels) is found, and other areas than the maximum area 81 are detected. A method of substituting a 0 value into a region to create one region on one line value and searching for one region on the one line value may be used.

  For example, since there are three areas 91, 92, and 93 on the horizontal dotted line in FIG. 9, it does not become a starting position for searching for the target organ, but the dotted line in FIG. 7B has one area. It can be the starting position at one place. The setting of the backprojection start position may be started from an area surrounded by the ROI 101 as shown in FIG.

  Also, the back projection start position is set to a position corresponding to the two binarized X-ray images (referred to as “binarized images”).

(Step 21)
The binarized image is subjected to back projection processing as shown in FIG. Here, since the shape of the back-projected region is to extract a blood vessel, in many cases, the cross-section is circular, so that the reconstruction region is approximated by a circle as shown in FIG. Further, as shown in FIG. 12, when the backprojection directions are orthogonal, the approximation is made by an ellipse. Thus, it can be set to an arbitrary shape from the anatomical knowledge of the target organ.

  For example, the setting of the arbitrary shape is such that an arbitrary shape such as a circle or an ellipse and menu information are displayed on the screen, and the displayed menu can be selected and input with the mouse according to the target organ.

(Step 22)
The backprojected image is reconstructed from the result of the backprojection, and the reconstructed tomographic image is stored on a magnetic disk or the like (image a).

(Step 23)
As shown in FIG. 7 (a), the reconstruction line of the tomographic image has its reconstruction position facing upward in the scanning line setting direction (FIGS. 7 (a) and 7 (b) upward, and downward in FIG. 7 (c)). ) Is updated by n (n = 1, 2, etc.).

(Step 24)
A tomogram is obtained for each update line by repeating binarization and backprojection for each update line (image b).

(Step 25)
Similarity between the backprojected image (image a) stored in step 22 and the tomogram (image b) backprojected in step 24 is obtained by correlation calculation, and the substantially same address of both tomographic images is the pixel “1”. If there is continuity, an area having no continuity is deleted from the image (b) as a false area.

  Further, “continuity” means that the subtraction between the images is performed and the sum of the subtraction is smaller than a predetermined value. As the correlation value, in the case of a binarized image, it may be the ratio that the pixel values of the corresponding pixels in both image regions are both pixels “1”.

  In the present invention, “correlation” and “continuity” include not only direct correlation between actual data but also correlation with data (not shown) obtained by extrapolation.

  In this way, the tomographic image construction apparatus 10 can obtain an accurate tomographic image from which the false region is deleted.

(Step 26)
The tomographic image from which the false region is deleted is stored.

(Step 27)
For the two X-ray images by the cone beam X-ray sources 131 and 132 shown in FIG. 13 or the X-ray image obtained by translating the fan beam X-ray sources 141 and 142 as shown in FIG. The above processing (reconstruction of tomographic images and deletion of false regions) is repeated until the number of tomographic images necessary for the configuration is obtained.

  In the above description, scanning in the X direction and searching for one region above the line value are performed. However, when the Y direction scanning can be extracted more favorably, the following is performed. First, as shown in FIG. 15, the distribution of run lengths (number of continuous pixels) in the X direction and Y direction in FIG. 10 is obtained. If the peak value of the distribution is lower in the X direction scanning, the X direction scanning is correct. If they are different, the Y direction is selected. If the X direction or the Y direction is selected by mistake, an error message indicating that the scanning line direction is incorrect is displayed on the screen (not shown).

  When there are a plurality of peaks in the run length distribution, the scanning line direction is selected in consideration of the shape and size of the subject.

  Also, as shown in the flowchart of FIG. 16, the scanning line direction may be automatically determined from the run length distribution.

(Step 161)
As shown in FIG. 15, the relationship between the run lengths in the X direction and the Y direction is obtained. Then, it is determined whether or not the obtained average value of the X-direction run length is smaller than the average value of the Y-direction run length. The average value of the X-direction run lengths to be compared and determined may be a predetermined constant multiple of the average value. If the determination is small, the process proceeds to step 163, and if the determination is not small, the process proceeds to step 162.

(Step 162)
The scanning direction is set to the Y direction, binarization and back projection processing are performed, and the process proceeds to step 164.

(Step 163)
The scanning direction is set to the X direction, and binarization and back projection processing are performed.

(Step 164)
One region is selected based on the continuity described in step 25.

(Step 28)
It is determined whether or not the repetition of Step 22 to Step 26 is completed for the X-ray image obtained in Step 27.

(Step 29)
In a simple tubular blood vessel or the like, a real region can be extracted by performing the above-described process once. However, as shown in FIG. 7B, one direction (in the case of FIG. 10, from bottom to top) In some cases, it is not possible to extract all the real regions only by the continuity of. In such a case, it can be extracted by using the continuity in the opposite direction (in the case of FIGS. 7 (a), 7 (b) and 7 (c), from top to bottom). Therefore, when the scanning position reaches the end of the processing range, the scanning line setting direction is reversed, and back projection and false region deletion are repeated.

  Such a process may be repeated a predetermined number of times, or a reconstructed tomographic image may be displayed and an operator may input an instruction.

  As described above, by reversing the scanning line setting direction and repeating the process, it is possible to extract even the complicated blood vessels that are branched. For example, even a portion that cannot be extracted by one process (in this case, from the bottom to the top) as shown in FIG. 7B can be extracted by repeating the process as shown in FIG. 7C.

(Step 2A)
As described above, the tomographic image constructing apparatus 10 can obtain a tomographic image from an X-ray image. However, by forming a three-dimensional image from a tomographic image, the shape of the subject can be easily grasped. A three-dimensional image can be constructed by a surface method or a volume rendering method. The three-dimensional image is obtained by, for example, obtaining a plurality of adjacent tomographic images of the subject in the body axis direction of the subject, extracting one target organ, and virtually extracting the extracted target organ on the memory. It is configured by stacking the subject in the body axis direction and projecting the stacked target organs onto the projection plane.

  Further, as described in step 21, since the reconstruction area is approximated by a circle or an ellipse, when a three-dimensional image 173 is formed from the X-ray image 171 and the X-ray image 172 as shown in FIG. The size of the branching portion appears discontinuously changing. Therefore, the tomographic image forming apparatus 10 performs a combining process as shown in FIGS. 18 (a) to 18 (f).

First, as shown in FIG. 18A, the region is divided into two blood vessel regions 181 and 182 and one blood vessel region 183, and the regions 181, 182 and 183 are separated as shown in FIG. 18B. 18C and 18D show cross-sectional images of connection portions of the regions 181, 182, and 183. For example, when one blood vessel (183 in FIG. 18A) branches into two blood vessels (181 and 182 in FIG. 18A), a tomographic image (d) showing only one blood vessel (FIG. 18). (D)) is corrected. In this case, in the tomographic image (e) shown in FIG. 18 (e), the logical product region of the concentric circle 184 of the region 181 and one region of the tomographic image (d) and the concentric circle 185 of the tomographic image 182 and the tomographic image (d) Leave the logical product area, and modify others. The corrected result is shown in FIG. As a result, the regions 181, 182, and 183 are smoothly joined. An example of a concentric circle setting method is shown in FIG. The shortest distance dR of the edge portion between the region 181 and the region 182 is obtained by the equation (1):
dR = RO−rc1−rc2 (1)
Here, RO is the distance between the centers of the region 181 and the region 182, rc 1 is the radius of the region 181, and rc 2 is the radius of the region 182.

Using the thus obtained dR, the radius R1 of the concentric circle corresponding to the region 181 and the radius R2 of the concentric circle corresponding to the region 182 are obtained by equations (2) and (3), respectively:
R1 = rc1 + 0.5 x dR (2)
R2 = rc2 + 0.5 x dR (3)
(Step 2B)
A tomographic image or a three-dimensional image is displayed on the CRT 15.

  Next, application examples such as a catheter and a stent displayed in accordance with a three-dimensional image will be described.

  In FIG. 20, X-ray images (two-dimensional images) 201 and 202 having different imaging directions and a three-dimensional image 203 configured based on these X-ray images are displayed side by side. A catheter is superimposed on the two-dimensional images 201 and 202, and when these two-dimensional images 201 and 202 are used to form a three-dimensional image, the positional relationship of the catheter in the blood vessel is superimposed on the three-dimensional image 203. For example, it is displayed like a dotted line.

  In FIG. 21, a stent three-dimensional image 212 is superimposed on a three-dimensional blood vessel image 211 and displayed. In the stent three-dimensional image 212, a plurality of types of stent images are stored on the magnetic disk. For example, when the soft switch 213 displayed on the screen “Stent 3D” is controlled with a mouse, the positional relationship between the blood vessel and the stent is displayed superimposed on the blood vessel three-dimensional image 211. The target of superimposition with the stent image is a two-dimensional X-ray image, and may be displayed simultaneously with the superimposition image with the three-dimensional image. As a result, the three-dimensional and planar shape of the stent can be grasped.

  According to the present embodiment, the binarized image creating function for creating a plurality of binarized images by binarizing each of a plurality of X-ray images of the subject taken by the X-ray apparatus 1B on the CPU 11; A scanning line setting function for setting scanning lines that sequentially move in predetermined directions to positions corresponding to each other of the plurality of binarized images created by the binarized image creating function, and the scanning line setting function Since it has a tomographic image forming function for forming a tomographic image by back projecting the pixel points of the plurality of binarized images at the position where the scanning line sequentially moves, considering reduction of X-ray exposure to the subject, A tomographic image of the subject can be obtained using a smaller number of X-ray images, that is, two X-ray images. The X-ray image here includes a digital image taken using a flat detector or the like, or an image obtained by digitizing a film image. Further, the smaller number than the above may be three or more X-ray images. In this case, although the effect of reducing the X-ray exposure is reduced, the accuracy of the resulting tomographic image is improved. Further, in the present embodiment, the procedure for performing the back projection processing for obtaining the tomographic image after creating the binarized image has been performed, but the procedure for constructing the binarized image after performing the back projection processing is also performed. The desired tomographic image can be constructed.

  Further, according to the present embodiment, the scanning line setting function is based on the correlation between the tomographic image in the forward direction and the reverse direction of the scanning line movement for each of the tomographic images formed by the tomographic image forming function. A false area detection function for detecting a false area and a false area detected by the false area detection function are deleted.

  As a result, the false region is deleted based on the correlation between the tomographic image in which the scanning line movement direction is the positive direction and the tomographic image in which the scanning line movement direction is the reverse direction. An image is obtained. If an area where the correlation is less than a predetermined value is detected, the area is a false area, so that the false area can be efficiently deleted.

  According to the present embodiment, the scanning line setting function scans one of the positions where the pixel value has a predetermined value on the scanning line and the position designated by the operator. Set as the initial position of the line.

  As a result, the initial position of the scanning line can be arbitrarily set, so if it is set in the vicinity of the region to be extracted, the binarized region for constructing the tomographic image can be moved more efficiently. As a result, the computation for constructing the tomographic image can be speeded up.

  Furthermore, according to this embodiment, when the scanning line reaches a predetermined position, the setting means reverses the scanning line direction and sets the position of the scanning line. By repeating the process in this way, a more accurate tomographic image can be obtained.

  As the predetermined position, the end of the tomographic image construction range in the X-ray image can be used.

(Second embodiment)
In the first embodiment, the case where tomographic image reconstruction and false region deletion are performed for each line has been described. First, a tomographic image is formed for a predetermined range, and then based on the correlation between the tomographic images. The false area may be deleted. The process in this case will be described below.

  FIG. 22 shows a reconstruction procedure of a tomographic image and a three-dimensional image according to this embodiment. FIG. 23 shows the principle of correlation processing of the reconstructed tomographic image. 24 to 28 are examples of backprojected images in FIG.

(Step 220)
As shown in FIG. 23, the X-ray image 31 is subjected to binarization processing in which the target organ is 1 and the other areas are 0. Similarly, the X-ray image 32 is subjected to binarization processing in which the target organ is 1 and the other areas are 0.

(Step 221)
The binarized image is subjected to back projection processing as shown in FIG. The shape of the back-projected region may be a polygon surrounded by a projection line as shown in FIG. 23A or a circular approximation as shown in FIG. In this circular approximation, the region expansion method may be used to narrow down after circular approximation. When the projection result is one area, the expansion start point may be used.

  Specifically, as shown in FIGS. 24 to 28, the X-ray image 31 is projected at the projection centers 241 to 281 and the X-ray image 32 is projected at the projection centers 242 to 282.

(Step 222)
The backprojected image is reconstructed from the result of the backprojection, and the reconstructed tomographic image is stored on a magnetic disk or the like (image a).

(Step 223)
The tomographic reconstruction line is updated by n (n = 1, 2, etc.).

(Step 224)
It is determined whether or not all the reconstruction lines of the tomographic image have been completed. If completed, the process proceeds to step 225. If not completed, the process returns to step 221.

  A tomographic image is obtained for each update line by repeating binarization and back projection for each update line.

(Step 225)
Steps 221 to 224 are repeated until, for example, FIG. 24, FIG. 25, FIG. 26, FIG. 27, and FIG. In this case, the result of FIG. 28 is searched.

(Step 226)
The region searched in Step 225 is a single region from the region 283 in FIG. 28 to the region 273 in FIG. 27, the region 263 in FIG. 26, the region 253 in FIG. 25, and the region 243 in FIG. look for. And the area | region which does not have continuity is deleted from FIG.24, FIG.25, FIG.26 as a false area | region. Further, at the time of this deletion, an image having a correlation of a certain ratio or more may be left at the end after back projection.

  In this way, the tomographic image construction apparatus 10 can obtain an accurate tomographic image from which the false region is deleted.

(Step 227)
The tomographic image from which the false region is deleted is stored.

(Step 228)
The lines of the binarized image are updated until the number of tomographic images necessary for three-dimensional image reconstruction is obtained.

(Step 229)
The line update in step 228 determines whether all lines have been completed. If all lines have been completed, the process proceeds to step 22A. If all lines have not been completed, the process returns to step 226.

(Step 22A)
In the tomographic image construction process, it is determined whether or not the process of reversing the scanning line direction has been completed. If the repetition process is completed, the process proceeds to step 22C. If the repetition process is not completed, the process proceeds to step 22B.

(Step 22B)
The tomographic image construction process is performed by reversing the scanning line direction. The reversal of the scanning line direction means that when a scanning line is first updated from the upper part to the lower part of the binarized image, for example, the scanning line is updated from the lower part to the upper part of the image.

(Step 22C)
The three-dimensional image is composed of tomographic images stored in step 227 (step 22D).
A tomographic image or a three-dimensional image is displayed on the CRT 15.

  The procedure shown in this embodiment can reconstruct a tomographic image from an X-ray image and delete a false region as in the case of the first embodiment.

  In addition, according to the present embodiment, as shown in FIG. 29, a three-dimensional image 291 obtained by moving the projection center of the three-dimensional image 291 and the three-dimensional image 291 in the X direction, and a three-dimensional image obtained by inverting the three-dimensional image 292. 30, a three-dimensional image 301 obtained by moving the projection center of the three-dimensional image 291 in the Y direction, a three-dimensional image 302 obtained by moving the projection center of the three-dimensional image 301 in the X direction, as illustrated in FIG. Various three-dimensional images such as a three-dimensional image 303 obtained by inverting the image 302 can be formed. In addition, it is possible to extract tomograms and three-dimensional images by extracting even the details of branched complex blood vessels.

  The setting of the number of X-ray images used for the reconstruction of the tomographic image and the application of the reconstructed tomographic image to the three-dimensional image can be performed as in the first embodiment.

  As described above, according to the present invention, a tomographic image can be reconstructed from an X-ray image.

FIG. 1 is a diagram showing a hardware configuration of a tomographic image forming apparatus according to the first embodiment of the present invention; FIG. 2 is a diagram showing a processing procedure for tomographic image construction; FIG. 3 is a diagram showing the positional relationship between an X-ray image, a tomographic image, and a three-dimensional image; FIG. 4 is a diagram showing an example of the relationship between the scanning line direction of a binarized image and one region; FIG. 5 is a diagram showing an example of a run length distribution; FIG. 6 is a diagram showing a back-projected image in the case of a binarized image with one area. 7 (a), 7 (b) and 7 (c) are diagrams showing the back projection start position and its movement in the binarized image; FIG. 8 is a diagram showing an example of using run length when the target organ is one; FIG. 9 is a diagram showing an example of the relationship between three subjects and X-ray images; FIG. 10 is a diagram showing an example of a case where the back projection start position is surrounded by an ROI; FIG. 11 is a diagram showing an example of circular approximation of a backprojected image; FIG. 12 shows a case where the reconstruction area can be approximated by an ellipse; FIG. 13 is a diagram showing an example of cone beam reconstruction of a tomographic image; FIG. 14 is a diagram showing an approximate reconstruction of a tomogram; FIG. 15 is a diagram showing a case where the X-ray image of FIG. 10 is binarized and back-projected; FIG. 16 is a flowchart for determining the scan line direction; FIG. 17 is a diagram showing an example of a branched three-dimensional image; 18 (a) to 18 (f) are diagrams showing an example of correction processing of a branch portion; FIG. 19 is a diagram showing a concentric circle setting method in the correction processing of the bifurcation; FIG. 20 is an example of superimposed display of a three-dimensional image and a catheter image; FIG. 21 is an example of a superimposed display of a three-dimensional image and a stent image; FIG. 22 is a diagram showing a processing procedure for constructing a tomographic image; FIG. 23 is a diagram showing correlation processing after back projection for all lines; FIG. 24 is a diagram showing an example of a backprojected image when there are a plurality of one regions in the binarized image; FIG. 25 is a diagram showing another example of the backprojected image when there are a plurality of one regions in the binarized image; FIG. 26 is a diagram showing another example of a backprojected image when there are a plurality of one regions in the binarized image; FIG. 27 is a diagram showing an example of a backprojected image when one region is present in the binarized image; FIG. 28 is a diagram showing another example of a backprojected image in the case where there is one area in the binarized image; FIG. 29 is a diagram showing an example when a three-dimensional image composed of tomographic images is viewed from the lateral direction; FIG. 30 is a diagram illustrating an example when a three-dimensional image configured from tomographic images is viewed from an oblique direction.

Claims (11)

Binarized image creating means for binarizing each of a plurality of X-ray images from a plurality of different directions of the subject imaged by the X-ray apparatus to create a plurality of binarized images;
Scanning line setting means for setting scanning lines that sequentially move in a predetermined direction to positions corresponding to each other of the plurality of binarized images created by the binarized image creating means;
A tomographic image forming unit configured to form a tomographic image by back projecting pixel points of the plurality of binarized images at positions where the scanning lines set by the scanning line setting unit sequentially move,
The scanning line setting means calculates a run length appearance frequency in a two-dimensional scanning line direction, and sets one of the two-dimensional scanning line directions based on the calculated appearance frequency. A tomographic image forming apparatus comprising means.   The scanning line setting means detects a false area for each of the tomographic images formed by the tomographic image forming means based on the correlation between the tomographic image in the forward direction and the reverse direction of the movement of the scanning line. The tomographic image forming apparatus according to claim 1, further comprising: a false area deleting unit that deletes the false area detected by the false area detecting unit.   The tomographic image constructing apparatus according to claim 2, wherein the false region deleting unit forms a plurality of tomographic images for a predetermined range and deletes the false regions based on a correlation between the subsequent tomographic images. .   The scanning line setting unit sets, as an initial position of the scanning line, one of a position where the pixel value takes a predetermined value on the scanning line and a position designated by the operator. The tomographic image forming apparatus according to claim 1, wherein:   2. The tomographic image constructing unit includes an approximate shape setting unit configured to set an approximate shape of the target organ according to the shape of the target organ when the tomographic image is configured. Tomographic image construction device. A plurality of tomographic images formed by the tomographic image forming means adjacent to each other, and a three-dimensional image forming means for forming a three-dimensional image from the plurality of formed tomographic images by a predetermined rendering method;
2. The tomographic image construction apparatus according to claim 1, further comprising image display means for displaying a three-dimensional image constituted by the three-dimensional image construction means.   The three-dimensional image constructing means composes a three-dimensional catheter image from the catheter portions included in the plurality of X-ray images, and the image display means comprises the constructed three-dimensional catheter image and the three-dimensional image constructing means. The tomographic image forming apparatus according to claim 6, wherein the tomographic image forming apparatus displays the superimposed three-dimensional image in a superimposed manner. Binarized image creating means for binarizing each of a plurality of X-ray images from a plurality of different directions of the subject imaged by the X-ray apparatus to create a plurality of binarized images;
Scanning line setting means for setting scanning lines that sequentially move in a predetermined direction to positions corresponding to each other of the plurality of binarized images created by the binarized image creating means, the scanning line setting direction being two-dimensional A scanning line setting unit including a scanning line direction setting unit configured to calculate a run length appearance frequency and set one of the two-dimensional scanning line directions based on the calculated appearance frequency ;
A tomographic image constructing means for constructing a tomographic image by back projecting pixel points of the plurality of binarized images at positions where the scanning lines set by the scanning line setting means sequentially move;
A plurality of tomographic images formed by the tomographic image forming means adjacent to each other, and a three-dimensional image forming means for forming a three-dimensional image from the plurality of formed tomographic images by a predetermined rendering method;
Image display means for displaying a three-dimensional image constituted by the three-dimensional image construction means;
Separation calculation means for separating and calculating a branch part of the three-dimensional image constituted by the three-dimensional image construction means;
A tomographic image construction apparatus comprising: a concatenation computing unit that obtains concentric circles of the branch portion separated and computed by the separation computation unit, and smoothly joins and computes the branch portions based on the concentric circles. Binarized image creating means for binarizing each of a plurality of X-ray images from a plurality of different directions of the subject imaged by the X-ray apparatus to create a plurality of binarized images;
Scanning line setting means for setting scanning lines that sequentially move in a predetermined direction to positions corresponding to each other of the plurality of binarized images created by the binarized image creating means, the scanning line setting direction being two-dimensional A scanning line setting unit including a scanning line direction setting unit configured to calculate a run length appearance frequency and set one of the two-dimensional scanning line directions based on the calculated appearance frequency ;
A tomographic image constructing means for constructing a tomographic image by back projecting pixel points of the plurality of binarized images at positions where the scanning lines set by the scanning line setting means sequentially move;
A plurality of tomographic images formed by the tomographic image forming means adjacent to each other, and a three-dimensional image forming means for forming a three-dimensional image from the plurality of formed tomographic images by a predetermined rendering method;
Image display means for displaying a three-dimensional image constituted by the three-dimensional image construction means;
A stent image storage means for storing a plurality of stent images;
A stent image reading means for reading a desired stent image from a plurality of stents stored by the stent image storage means,
The tomographic image construction apparatus, wherein the image display means superimposes and displays the stent image read by the stent image readout means and the 3D image constituted by the 3D image construction means. A binarized image creating step for binarizing each of the X-ray images from a plurality of different directions of the subject imaged by the X-ray device to create a plurality of binarized images;
A scan line that sequentially moves in a predetermined direction is set at a position corresponding to each other of the plurality of binarized images created by the binarized image creating step, and the appearance frequency of run length is calculated in the two-dimensional scan line direction. A scanning line setting step for setting one of the two-dimensional scanning line directions based on the calculated appearance frequency ;
A tomographic image forming step of forming a tomographic image by back projecting pixel points of the plurality of binarized images at positions where the scanning lines set by the scanning line setting step sequentially move;
A plurality of tomographic images configured by the tomographic image configuration step are configured adjacently, and a three-dimensional image configuration step of configuring a three-dimensional image from the plurality of configured tomographic images by a predetermined rendering method;
An image display step for displaying the three-dimensional image constructed by the three-dimensional image construction step;
A separation calculation step of separating and calculating a branch portion of the three-dimensional image constituted by the three-dimensional image construction step;
A tomographic image constructing method comprising: a concatenation calculation step of obtaining concentric circles of the branch portions subjected to the separation operation in the separation operation step and smoothly combining the branch portions based on the concentric circles. A binarized image creating step for binarizing each of the X-ray images from a plurality of different directions of the subject imaged by the X-ray device to create a plurality of binarized images;
A scan line that sequentially moves in a predetermined direction is set at a position corresponding to each other of the plurality of binarized images created by the binarized image creating step, and the appearance frequency of run length is calculated in the two-dimensional scan line direction. A scanning line setting step for setting one of the two-dimensional scanning line directions based on the calculated appearance frequency ;
A tomographic image forming step of forming a tomographic image by back projecting pixel points of the plurality of binarized images at positions where the scanning lines set by the scanning line setting step sequentially move;
A plurality of tomographic images configured by the tomographic image configuration step are configured adjacently, and a three-dimensional image configuration step of configuring a three-dimensional image from the plurality of configured tomographic images by a predetermined rendering method;
An image display step for displaying the three-dimensional image constructed by the three-dimensional image construction step;
A stent image storing step of storing a plurality of stent images;
A stent image reading step of reading a desired stent image from a plurality of stents stored by the stent image storage step,
The tomographic image construction method characterized in that the image display step superimposes and displays the stent image read by the stent image readout step and the three-dimensional image constructed by the three-dimensional image construction step.

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