JP2011104027A - Method and program of generating binary image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform inter-image interpolation in a short time while keeping a binary image without change. <P>SOLUTION: In a method of generating a third binary image held between a first binary image and a second binary image, the method includes: a step of acquiring respective centers of gravity of the first and second binary images; a step of moving the image to fit the centers of gravity of the first and second binary images; a step of setting a plurality of moving radii by using the fit center of gravity as an origin; a step of setting an intersection point with an edge of the first binary image on each moving radius as a first intersection point and an intersection point with an edge of the second binary image as a second intersection point with respect to the plurality of moving radii; a step of obtaining a third point between the first and second intersection points on each moving radius; a step of setting the third binary image by using the line obtained by connecting the third points as an edge; and a step of moving the third binary image in a manner that the center of gravity of the third binary image is disposed between the first and second centers of gravity. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an interpolation calculation between images of an X-ray CT apparatus, an MRI apparatus, and an ultrasonic diagnostic apparatus, and more particularly to a technique for inter-image interpolation of binary images.

  Three-dimensional images are beginning to be widely used in the field of CT image diagnosis due to their improved image quality, high-speed reconstruction, and real-time display of multidirectional observation images.

  In such reconstruction of a three-dimensional image, there is a processing step in which threshold processing is performed based on a plurality of tomographic images obtained by X-ray CT and contour extraction of a desired organ is performed. The image thus obtained is a binary image.

  On the other hand, in the X-ray CT apparatus, the CT value of the bone is slightly different for each image due to an error during reconstruction of the CT image. For example, as shown in FIG. 2, when extracting a bone region as a binary image from a plurality of tomographic images by threshold processing, it is extracted because the bone density is low as shown in N + 2 in FIG. May fail. In such a case, N + 1 and N + 3th upper and lower (or front and back) images may be used to obtain the result by interpolation.

  According to the prior art described in Patent Document 1, in an image interpolation method for interpolating a binary image, a multi-value image is created from the binary image, and after performing an interpolation operation on the multi-value image, the image is returned to the binary image again. An image interpolation method for obtaining an interpolated binary image is shown.

JP 4-111179 A

However, the conventional technique described in Patent Document 1 requires a long time for calculation because it requires complicated calculation steps.
An object of the present invention is to perform inter-image interpolation in a short time while a binary image remains as a binary image.

In order to solve the above problem, according to the present invention, a third binary image sandwiched between a first binary image and a second binary image is converted into the first binary image and the first binary image. A binary image generation method for generating based on two binary images,
Obtaining the center of gravity of the first binary image and the center of gravity of the second binary image, respectively;
Moving one or both of the first binary image and the second binary image so that the center of gravity of the first binary image and the center of gravity of the second binary image are aligned, and the alignment Setting a plurality of moving radii with the center of gravity as an origin, and for the plurality of moving radii, an intersection point of the edge of the first binary image on each moving radius as a first intersection point, A step of setting each of the intersection points of the two binary images as a second intersection point, and a third point between each of the first intersection point and the second intersection point on each radius by interpolation. Obtaining a third binary image by combining the third point with the third point as an edge, and the third two points between the first centroid and the second centroid. And moving the third binary image so that the center of gravity of the value image is arranged. A method is provided.

  Further, according to the present invention, the third binary image sandwiched between the first binary image and the second binary image is based on the first binary image and the second binary image. A method for generating a binary image, the step of obtaining an overlapping region of the first binary image and the second binary image, a step of obtaining a center of gravity of the overlapping region, and using the center of gravity as an origin A step of setting a plurality of radiuses, and on each radius, an intersection of the radius and the edge of the first binary image, and an intersection of the radius and the edge of the second binary image There is provided a binary image generation method comprising the steps of obtaining respective internal dividing points, and combining the internal dividing points and setting a third binary image using the internal dividing points as edges.

Further, according to the present invention, a third binary image sandwiched between the first binary image and the second binary image is stored in the computer, the first binary image and the second binary image. A binary image generation program generated based on an image,
The program combines the function of obtaining the center of gravity of the first binary image and the center of gravity of the second binary image, and the center of gravity of the first binary image and the center of gravity of the second binary image. As described above, the function of moving one or both of the first binary image and the second binary image, the function of setting a plurality of radiuses with the combined center of gravity as the origin, and the plurality of radiuses On the other hand, the function of setting the intersection point with the edge of the first binary image on each radius as the first intersection point and the intersection point with the edge of the second binary image as the second intersection point, respectively. And the third point between each of the first intersection and the second intersection on each radius by interpolation, and the third point is combined with the third point as an edge. A function of setting a binary image of the third binary image, and the center of gravity of the third binary image is arranged between the first center of gravity and the second center of gravity. A binary image generation program is provided that executes a binary image moving function.

  Further, according to the present invention, a third binary image sandwiched between the first binary image and the second binary image is stored in the computer, the first binary image and the second binary image. A binary image generation program to be generated based on an image, the program including a function for obtaining an overlapping area between the first binary image and the second binary image, and a function for obtaining a center of gravity of the overlapping area. , A function of setting a plurality of radiuses with the center of gravity as the origin, an intersection of the radius and the edge of the first binary image on each radius, and the radius and the second binary value A function for obtaining an internal dividing point of an intersection with an edge of an image and a function for combining the inner dividing points and setting a third binary image using the inner dividing point as an edge A binary image generation program is provided.

  According to the present invention, it is possible to interpolate between binary images while maintaining the binary image as it is, and interpolation calculation can be performed in a shorter calculation time than in the past.

1 is an overall configuration diagram of an X-ray CT apparatus 1 to which the present invention is applied. It is a figure which shows the example from which the organ was extracted with the binary image on the Nth to N + 3th slice about the parallel several image obtained with the X-ray CT apparatus. 3 is a flowchart for explaining the first embodiment. The figure which displayed the N + 1th binary image and the N + 3th binary image on one screen in a superimposed manner. The figure showing the result of having moved parallel so that the gravity center of the N + 1th binary image and the N + 3th binary image may match. 9 is a flowchart for explaining the second embodiment. The figure which calculated | required the gravity center of the overlap area | region. The figure which shows the operation screen in this invention.

An X-ray CT apparatus to which the present invention is applied will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram of an X-ray CT apparatus 1 to which the present invention is applied. The X-ray CT apparatus 1 includes a scan gantry unit 100 and a console 120.

  The scan gantry unit 100 includes an X-ray tube 101, a rotating disk 102, a collimator 103, an X-ray detector 106, a data collection device 107, a bed 105, a gantry control device 108, a bed control device 109, An X-ray control device 110. The X-ray tube 101 is a device that irradiates a subject placed on a bed 105 with X-rays. The collimator 103 is a device that limits the radiation range of X-rays emitted from the X-ray tube 101. The rotating disk 102 includes an opening 104 into which the subject placed on the bed 105 enters, and is equipped with an X-ray tube 101 and an X-ray detector 106, and rotates around the subject. The X-ray detector 106 is a device that measures the spatial distribution of transmitted X-rays by detecting X-rays that are placed opposite to the X-ray tube 101 and transmitted through the subject, and rotates a number of X-ray detection elements. They are arranged in the rotating direction of the disk 102, or arranged two-dimensionally in the rotating direction of the rotating disk 102 and the rotating shaft direction.

  The data collection device 107 is a device that collects the X-ray dose detected by the X-ray detector 106 as digital data. The gantry control device 108 is a device that controls the rotation of the rotary disk 102. The bed control device 109 is a device that controls the vertical movement of the bed 105. The X-ray control device 110 is a device that controls electric power input to the X-ray tube 101.

  The console 120 includes an input device 121, an image arithmetic device 122, a display device 125, a storage device 123, and a system control device 124. The input device 121 is a device for inputting a subject's name, examination date and time, imaging conditions, and the like, specifically a keyboard or a pointing device. The image computation device 122 is a device that performs CT processing on the measurement data sent from the data collection device 107 and performs CT image reconstruction. The display device 125 is a device that displays the CT image created by the image calculation device 122, and is specifically a CRT (Cathode-Ray Tube), a liquid crystal display, or the like. The storage device 123 is a device that stores data collected by the data collection device 107 and image data of a CT image created by the image calculation device 122, and is specifically an HDD (Hard Disk Drive) or the like. The system control device 124 is a device that controls these devices, the gantry control device 108, the bed control device 109, and the X-ray control device 110.

  The X-ray tube 101 performs imaging by controlling the power input to the X-ray tube 101 by the X-ray control device 110 based on the imaging conditions input from the input device 121, particularly the X-ray tube voltage and X-ray tube current. The subject is irradiated with X-rays according to conditions. The X-ray detector 106 detects X-rays irradiated from the X-ray tube 101 and transmitted through the subject with a large number of X-ray detection elements, and measures the distribution of transmitted X-rays. The rotating disk 102 is controlled by the gantry control device 108, and rotates based on the photographing conditions input from the input device 121, particularly the rotation speed. The couch 105 is controlled by the couch controller 109 and operates based on the photographing conditions input from the input device 121, particularly the helical pitch.

  By repeating the X-ray irradiation from the X-ray tube 101 and the measurement of the transmitted X-ray distribution by the X-ray detector 106 along with the rotation of the rotating disk 102, projection data from various angles is acquired. The acquired projection data from various angles is transmitted to the image calculation device 122. The image calculation device 122 reconstructs the CT image by performing back projection processing on the transmitted projection data from various angles. The CT image obtained by the reconstruction is displayed on the display device 125.

  Next, FIG. 2 shows an example in which an organ is extracted as a binary image on the Nth to N + 3th slices of a plurality of parallel images obtained by the X-ray CT apparatus. Then, 1A is extracted in the Nth slice, 1B is extracted in the N + 1th slice, not extracted in the N + 2th slice, and 1C is extracted in the N + 3th slice. ing. Here, the N + 2th image (third binary image) sandwiched between the N + 1th and N + 3th binary images (first binary image and second binary image) Since there has been an extraction error, an example of performing (generating) a binary image of the (N + 2) th image based on the (N + 1) th and (N + 3) th binary images is shown below.

  The first embodiment will be described with reference to the flowchart of FIG. 3 and FIGS.

(Step 31)
First, the N + 1st binary image and the N + 3th binary image are superimposed and displayed on one screen as shown in FIG. Thereafter, an overlapping area between the N + 1st and N + 3rd extraction areas is detected. A diagram in which the overlapping area is detected is indicated by the oblique lines in FIG. If there is an overlapping region, the process proceeds to step 32. If there is no overlapping area, the process ends.

(Step 32)
Next, the centroid (the centroid of the first binary image and the centroid of the second binary image) of each of the two areas indicated by the N + 1 and N + 2 binary images including the overlapping area is obtained. . The center of gravity of each region is O ₁ and O ₂ as shown in FIG.

(Step 33)
One or both of the (N + 1) -th binary image and the (N + 3) -th binary image are moved (parallel) so that the centers of gravity of the (N + 1) -th binary image and the (N + 3) -th binary image are aligned. The result of translation is as shown in FIG. FIG. 5 (b) is an enlarged view of FIG. 5 (a). Let O be the combined center of gravity.

(Step 34)
As shown in FIG. 5, a plurality of moving radii are set with the combined center of gravity O as the origin. The moving radius is a line segment drawn in a radial shape with the center of gravity O as the center, and indicates a line segment arranged to rotate 360 degrees like a watch hand.

(Step 35)
For the plurality of radiuses, an intersection with the edge of the first binary image on each radius is Pk (first intersection), and an intersection with the edge of the second binary image Set each as Qk (second intersection).

(Step 36)
On each radius, Mk (third point), which is a point between Pk and Qk, is obtained by interpolation.
For example, the coordinates of Mk are obtained from equation (1) using Pk, Qk, and Rk.

Mk ＝ Rk ・ Pk ＋ (1−Rk) ・ Qk Equation (1)
(Step 37)
By combining Mk and using it as an edge, the (N + 2) th binary image (third binary image) is set. Specifically, in FIG. 5, a region surrounded by a dotted line is a region indicated by the (N + 2) th binary image.

(Step 38)
As the center of gravity of the N + 2-th binary image between O ₁ and O ₂ are arranged to move the N + 2-th binary image. Specifically, the centroid of the (N + 2) -th binary image is translated to a new centroid point obtained by interpolating O ₁ and O ₂ to obtain a binary image of the (N + 2) -th image.

  According to the present embodiment, an interpolation image can be obtained while the binary image remains as a binary image, so that there is an effect that an interpolation image of the binary image can be obtained in a short time.

  A second embodiment will be described with reference to the flowchart of FIG. 6 and FIG.

(Step 61)
First, when N + 1 binary image (first binary image) and N + 3 binary image (second binary image) are overlaid, they are displayed on one screen as shown in Fig. 7 (a). To do. Thereafter, an overlapping area between the N + 1st and N + 3rd extraction areas is obtained. The overlapping region is indicated by the oblique lines in FIG. If there is an overlapping region, the process proceeds to step 62. If there is no overlapping area, the process ends.

(Step 62)
Find the center of gravity of the overlap region. The figure which calculated | required the gravity center becomes like O of the enlarged view of FIG.7 (b).

(Step 63)
A plurality of radius vectors having the center of gravity O as the origin are set.

(Step 64)
On each radius, the intersection (P) of each radius and the edge of the N + 1th binary image, and the intersection (Q) of each radius and the edge of the N + 3th binary image Find the internal dividing point (M) of.

(Step 65)
N + 2th binary images (third binary images) are set by connecting the internal dividing points and using them as the edges.

  Also according to the present embodiment, since the interpolation image can be obtained while the binary image remains the binary image, there is an effect that the interpolation image of the binary image can be obtained in a short time.

  In the above embodiment, for the N + 1 and N + 3 sheets, “when there is an overlap” not only completely overlaps but also substantially means “distance between centroids <average diameter”. But it ’s okay.

  Here, the average diameter may be (a) the average diameter of the two regions, (b) the average diameter of the large region (R1), (c) the average diameter of the small region (R2), and (d) from both average diameters. The obtained value (r * R1 + (1.0−r) * R2) may be used.

  FIG. 8 shows an example of the operation screen in the present invention. 210 shows the extracted bone and psoas muscle. Reference numeral 212 denotes an extracted binary image at a position 211 that can be moved up and down by a mouse operation. In step S213, when “current image correction” is turned on, the displayed image is corrected by interpolation. When “all image correction” is turned on, for example, the entire image of the chest of one examinee taken on that day is corrected. If automatic correction does not work, use "Manual Correction" to correct it.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, a plurality of moving radii may be set by rotating the moving radii arranged in one direction from the combined centroid in the first embodiment or the centroid of the overlapping region in the second embodiment. Further, when connecting the third point in the first embodiment and the internal dividing point in the second embodiment, spline interpolation may be used. Further, the present invention may be embodied as a binary image generation program having the functions of the above steps and causing a computer to generate a third binary image.

  Further, in Example 1 and Example 2, the third binary image sandwiched therebetween was obtained based on the two first binary images and the second binary image. Nonlinear calculation may be performed using three or more images used to obtain a binary image. For example, in the second embodiment, the fourth image that is neither the first binary image nor the second binary image is used, and the second radius vector and the fourth radius are arranged by using the center of gravity and the center of gravity as the origin. The intersection point with the binary image may be set as the third intersection point, the points between the three intersection points may be combined, and the third binary image may be set with the edge as an edge.

  The present invention can be used for an X-ray CT apparatus, an MRI apparatus, and an ultrasonic diagnostic apparatus.

  31 Steps for determining whether there are overlapping areas, 32 Steps for determining the center of gravity of each area, 33 Steps for translating to match the center of gravity, 34 Steps for setting multiple radials with the center of gravity O as the origin, 35 A step of setting an intersection with the edge (first intersection and second intersection), 36 a step of obtaining a point (third point) between the first intersection and the second intersection by interpolation, 37 third , Connecting the points, and setting a third binary image using it as an edge, and 38 moving the third binary image.

Claims (12)

A binary image generation method for generating a third binary image sandwiched between a first binary image and a second binary image based on the first binary image and the second binary image. There,
Obtaining a centroid of the first binary image and a centroid of the second binary image, respectively;
Moving one or both of the first binary image and the second binary image so as to match the centroid of the first binary image and the centroid of the second binary image;
Setting a plurality of radiuses with the combined center of gravity as the origin;
With respect to the plurality of radiuses, an intersection with the edge of the first binary image on each radius is a first intersection, and an intersection with the edge of the second binary image is a second A step to set each as an intersection,
Obtaining a third point between each of the first intersection and the second intersection on each radius by interpolation;
Combining the third points and setting a third binary image using the third point as an edge; and a centroid of the third binary image between the first centroid and the second centroid Moving the third binary image so that is arranged;
A binary image generation method comprising: The binary image generation method according to claim 1,
The method of generating a binary image, wherein the setting of the plurality of moving radii is performed by rotating a moving radii arranged in one direction from the combined center of gravity. The binary image generation method according to claim 1,
A spline interpolation is used for connecting the third points, and a binary image generating method is characterized. The binary image generation method according to claim 1,
A method of generating a binary image, comprising: a step of detecting an overlapping area between the first binary image and the second binary image before performing each of the steps. A binary image generation method for generating a third binary image sandwiched between a first binary image and a second binary image based on the first binary image and the second binary image. There,
Obtaining an overlapping region of the first binary image and the second binary image;
Obtaining a center of gravity of the overlapping region;
Setting a plurality of radiuses with the center of gravity as the origin;
Obtaining an intersection of the radius and the edge of the first binary image and an internal dividing point of the intersection of the radius and the edge of the second binary image on each radius; ,
Combining the inner dividing points and setting a third binary image using the inner dividing points as edges. The binary image generation method according to claim 5,
The binary image generation method according to claim 1, wherein the setting of the plurality of radius vectors is performed by rotating a radius vector arranged in one direction from the center of gravity. The binary image generation method according to claim 5,
A spline interpolation is used for connecting the third points, and a binary image generating method is characterized. The binary image generation method according to claim 5,
A method of generating a binary image, comprising: a step of detecting an overlapping area between the first binary image and the second binary image before performing each of the steps. The binary image generation method according to claim 5,
Using a fourth image that is neither the first binary image nor the second binary image, the center of gravity and the intersection of the second radius vector and the fourth binary image arranged with the center of gravity as the origin are used. A binary image generation method characterized in that, as a third intersection point, a point between the three intersection points is connected, and a third binary image is set using that point as an edge. A binary image that causes a computer to generate a third binary image sandwiched between the first binary image and the second binary image based on the first binary image and the second binary image. A generation program,
The program
A function for obtaining the center of gravity of the first binary image and the center of gravity of the second binary image,
A function of moving one or both of the first binary image and the second binary image so as to match the centroid of the first binary image and the centroid of the second binary image;
A function of setting a plurality of radiuses with the combined center of gravity as the origin;
With respect to the plurality of radiuses, an intersection with the edge of the first binary image on each radius is a first intersection, and an intersection with the edge of the second binary image is a second A function to set each as an intersection,
A function for obtaining a third point between each of the first intersection and the second intersection on each radius by interpolation;
A function of combining the third points and setting a third binary image using the third point as an edge; and a centroid of the third binary image between the first centroid and the second centroid A function of moving the third binary image so that
The binary image generation program characterized by performing this. A binary image that causes a computer to generate a third binary image sandwiched between the first binary image and the second binary image based on the first binary image and the second binary image. A generation program,
The program
A function for obtaining an overlapping area between the first binary image and the second binary image;
A function for obtaining the center of gravity of the overlapping region;
A function of setting a plurality of radials with the center of gravity as the origin;
A function for obtaining an intersection of the radius and the edge of the first binary image and an internal dividing point of the intersection of the radius and the edge of the second binary image on each radius; ,
A function of combining the inner dividing points and setting a third binary image using the inner dividing points as edges;
The binary image generation program characterized by performing this. A binary image generation program according to claim 11,
The program uses a fourth image that is neither the first binary image nor the second binary image, and uses the fourth centroid and a plurality of second radial images arranged with the centroid as the origin. A binary image generation characterized by executing a function of setting a third binary image using the intersection point between and the third intersection point as a third intersection point, and setting the third binary image as an edge. program.

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