JP2004057340A - Thrombus section image extraction method, image processor and x-ray ct system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thrombus section image extraction method, an image processor and an X-ray CT system, for simply measuring the size of a thrombus of aneurysm with high accuracy using image processing technology. <P>SOLUTION: The thrombus section image extraction method includes the steps of: extracting vicinity region containing a blood vessel in a vertical tomographic plane intersecting perpendicularly to the blood vessel (step S404); smoothing the vicinity region (step S405); extracting an approximation region of the thrombus section from the smoothed vicinity region by region expansion processing (step S408); and extracting a circular arc region from the approximate region of the thrombus section by circular arc processing (step S409). The approximate region of the thrombus section is extracted using the region expansion processing, the circular-arc thrombus section with high accuracy is extracted from the approximate region, and the evaluation on the area of thrombus and the quantitative evaluation on a temporal change of the area of thrombus are realized. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image processing apparatus of an X-ray CT apparatus that performs imaging using a contrast agent.
[0002]
[Prior art]
In recent years, X-ray CT imaging using an angiographic agent is performed for the purpose of imaging an aneurysm. An aneurysm consists of a blood vessel and a thrombus portion which adheres to the wall of the blood vessel and in which the blood solidifies in a jelly state. Here, in order to predict the progress of the aneurysm, it is important to obtain information on the blood vessel diameter of the aneurysm and the size of the thrombus. In imaging using a contrast agent, the blood vessel portion of the aneurysm is clearly depicted by the blood contrast agent.
[0003]
[Problems to be solved by the invention]
However, according to the above-mentioned prior art, the thrombus portion adhering to the blood vessel wall has no contrast effect, and it is difficult to identify the thrombus from the surrounding tissue. That is, the contrast agent did not flow into the thrombus portion, so that no contrast effect was observed.
[0004]
In particular, attempts have been made to extract and measure information on a thrombus portion that is difficult to identify using an image processing technique. However, light and shade of brightness called density unevenness exist in the thrombus portion, which is a factor that hinders measurement of the thrombus portion using image processing technology.
[0005]
From these facts, how to realize a thrombus portion image extraction method, an image processing apparatus, and an X-ray CT system that can easily and highly accurately measure the size of a thrombus of an aneurysm using image processing technology. It becomes important.
[0006]
The present invention has been made in order to solve the above-described problems of the related art, and the thrombus size of a thrombus of an aneurysm can be measured easily and with high accuracy using an image processing technique. An object is to provide an extraction method, an image processing device, and an X-ray CT system.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve the object, a thrombus portion image extracting method according to a first aspect of the present invention obtains a plurality of pieces of tomographic image information of a subject using an X-ray CT apparatus, and obtains the tomographic image information. Generates a plurality of pieces of vertical tomographic image information that intersects perpendicularly with the direction of blood flow in the blood vessel, extracts a region near the blood vessel including the blood vessel from the image of the vertical tomographic image information, and smoothes the image of the nearby region. Extracting an approximate region of a thrombus portion adhering to the blood vessel from the smoothed image, and determining an edge of the thrombus region in an arc shape.
[0008]
According to the invention of the first aspect, a plurality of tomographic image information of the subject is acquired by the X-ray CT apparatus, and a plurality of pieces of vertical tomographic image information that intersects perpendicularly with the blood flow direction in the blood vessel are obtained from the tomographic image information. Generate and extract a region near a blood vessel including a blood vessel from the image of the vertical tomographic image information, smooth the image of the nearby region, and extract an approximate region of a thrombus portion attached to the blood vessel from the smoothed image. Since the edge of this approximate area is determined to be an arc, the density unevenness existing in the thrombus is smoothed, the approximate area of the thrombus is extracted, and the edge of the extracted part is further determined to be an arc. As a result, a highly accurate thrombus region can be extracted, and as a result, a thrombus area can be evaluated and a quantitative evaluation such as a temporal change in the thrombus area can be performed.
[0009]
Further, the image processing apparatus according to the second aspect of the present invention acquires a plurality of tomographic image information of a subject from an X-ray CT apparatus, and from the tomographic image information, a plurality of perpendicular to the blood flow direction in a blood vessel. An image processing apparatus for generating tomographic image information, comprising: an extracting unit configured to extract a region near the blood vessel including the blood vessel from an image of the vertical tomographic image information; and a smoothing unit configured to smooth an image of the nearby region. A region expansion unit that extracts a region having a pixel value in a specified range from the smoothed image; and a determination unit that determines the edge of the approximate region in an arc shape.
[0010]
According to the invention according to the second aspect, the extraction unit extracts the vicinity region of the blood vessel including the blood vessel from the vertical tomographic image information, smoothes the image of the vicinity region by the averaging unit, and designates the designated region by the region expansion unit. Since the region having the pixel value of the range is extracted and the edge of the thrombus region is determined to be an arc by the determination means, the density unevenness existing in the thrombus portion is smoothed, and the approximate region of the thrombus portion is extracted. It is possible to further determine the edge of this approximate area in an arc shape and extract a highly accurate thrombus area, and thus to perform thrombus area evaluation and quantitative evaluation such as temporal change in thrombus area. .
[0011]
An image processing apparatus according to a third aspect of the present invention is characterized in that the extraction means includes a threshold means for extracting an image area having a pixel value exceeding a threshold or a pixel value not exceeding a threshold.
[0012]
According to the invention of the third aspect, the extracting means extracts the image area having the pixel value exceeding the threshold value or the pixel value not exceeding the threshold value by the threshold value means. By extracting a background region, image information consisting of only a soft tissue portion can be generated.
[0013]
Further, an image processing apparatus according to a fourth aspect of the invention is characterized in that the extraction means includes a region of interest setting means for setting a region of interest.
According to the fourth aspect of the invention, since the region of interest is set by the region of interest setting unit, the extraction unit can extract a region near a blood vessel including a blood vessel from the soft tissue.
[0014]
The image processing apparatus according to a fifth aspect of the present invention stores the range of the region of interest in the region of interest setting means, and stores the range in a plurality of tomographic images close to the tomographic image of the vertical tomographic image information. It is characterized by comprising resetting means for setting.
[0015]
According to the fifth aspect of the invention, the region of interest setting means stores the range of the region of interest by the resetting means and sets the range in a plurality of tomographic images close to the tomographic image of the vertical tomographic image information. Therefore, it is not necessary to set a region of interest for each adjacent tomographic image.
[0016]
Further, the image processing apparatus according to the invention of a sixth aspect is characterized in that the smoothing means includes a spatial filter having a size of a mask area for smoothing density unevenness of the thrombus area.
[0017]
According to the sixth aspect of the invention, since the smoothing means has the spatial filter having the size of the mask area for smoothing the density unevenness in the thrombus area, the smoothing means can smooth the density unevenness in the thrombus area. it can.
[0018]
An image processing apparatus according to a seventh aspect of the present invention is characterized in that the spatial filter includes a changing unit that changes a size of a mask area.
According to the seventh aspect of the invention, since the spatial filter changes the size of the mask area by the changing unit, even when individual differences exist in the density unevenness of the thrombus area, the spatial filter can reduce the density unevenness. Can be smoothed.
[0019]
An image processing apparatus according to an eighth aspect of the present invention is characterized in that the edge is approximated by a circular arc by the determination means.
According to the eighth aspect of the invention, since the determining means approximates the periphery with a circular arc, it is possible to extract a thrombus region around a blood vessel having a substantially circular shape with high accuracy.
[0020]
An X-ray CT system according to a ninth aspect of the present invention irradiates a subject with an X-ray beam, collects projection data of the subject, and reconstructs a tomographic image of the subject by image reconstruction of the projection data. An X-ray CT apparatus that acquires image information; a transfer unit that transfers the tomographic image information of the X-ray CT apparatus; An image processing apparatus for generating a plurality of intersecting vertical tomographic image information, wherein the image processing apparatus extracts a region near the blood vessel including the blood vessel from an image of the vertical tomographic image information. Extracting means, a smoothing means for smoothing the image of the neighboring area, an area expanding means for extracting an area having a pixel value in a specified range from the smoothed image, and an edge of the thrombus area. Arc shape And determining means for determining, characterized in that it comprises a.
[0021]
According to the ninth aspect, in the image processing apparatus, the extracting unit extracts a region near the blood vessel including the blood vessel from the image of the vertical tomographic image information, and the smoothing unit smoothes the image of the nearby region. Since the region expanding means extracts a region having a pixel value in a specified range from the smoothed image, and the deciding device decides the periphery of the thrombus region in an arc shape, the region exists in the thrombus portion. The density unevenness is smoothed, an approximate region of the thrombus portion is extracted, and the edge of the approximate region is further determined in an arc shape, so that a thrombus region with high accuracy can be extracted.Thus, evaluation of thrombus area and thrombus It is possible to perform a quantitative evaluation such as a temporal change of the area.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
DESCRIPTION OF EMBODIMENTS Preferred embodiments of a thrombus portion image extraction method, an image processing device, and an X-ray CT system according to the present invention will be described below with reference to the accompanying drawings. Note that the present invention is not limited to this.
[0023]
First, an overall configuration of an image processing apparatus and an X-ray CT system according to the present embodiment will be described. FIG. 1 shows a block diagram of the X-ray CT apparatus. As shown in FIG. 1, the apparatus includes a scanning gantry 2 and an operation console 6.
[0024]
The scanning gantry 2 has an X-ray tube 20. An X-ray (not shown) emitted from the X-ray tube 20 is shaped by a collimator 22 into, for example, a fan-shaped X-ray beam (beam), that is, a fan beam X-ray, and a detector array (array). ) 24.
[0025]
The detector array 24 has a plurality of X-ray detection elements arranged in an array in the direction in which the fan beam X-rays spread. The detector array 24 is a multi-channel (channel) X-ray detector in which a plurality of X-ray detection elements are arranged in an array.
[0026]
The plurality of detector arrays 24 form an X-ray incident surface curved as a cylindrical concave surface as a whole. The detector array 24 is composed of, for example, a combination of a scintillator and a photodiode. The present invention is not limited to this, and may be, for example, a semiconductor X-ray detection element using cadmium tellurium (CdTe) or the like or an ionization box type X-ray detection element using Xe gas (gas). The X-ray tube 20, the collimator 22, and the detector array 24 constitute an X-ray irradiation / detection device.
[0027]
A data collection unit 26 is connected to the detector array 24. The data collection unit 26 collects detection data of individual X-ray detection elements of the detector array 24. The irradiation of X-rays from the X-ray tube 20 is controlled by an X-ray controller 28. The connection relationship between the X-ray tube 20 and the X-ray controller 28 and the connection relationship between the collimator 22 and the collimator controller 30 are not shown. The collimator 22 is controlled by a collimator controller 30.
[0028]
The components from the X-ray tube 20 to the collimator controller 30 are mounted on the rotating unit 34 of the scanning gantry 2. Here, the subject 1 is placed on a cradle 31 in a bore 29 located at the center of the rotating unit 34 in a lying state. The rotation unit 34 rotates while being controlled by the rotation controller 36, emits X-rays from the X-ray tube 20, and detects transmitted X-rays of the subject 1 in the detector array 24. The illustration of the connection relationship between the rotation unit 34 and the rotation controller 36 is omitted.
[0029]
The operation console 6 has an image reconstruction unit 60. The image reconstruction unit 60 is configured by, for example, a computer. The image reconstruction unit 60 is connected to a control interface (interface) 62. The scanning gantry 2 is connected to the control interface 62. The image reconstruction unit 60 controls the scanning gantry 2 through the control interface 62.
[0030]
The data acquisition unit 26, X-ray controller 28, collimator controller 30, and rotation controller 36 in the scanning gantry 2 are controlled through a control interface 62. It should be noted that illustration of individual connections between these units and the control interface 62 is omitted.
[0031]
The image reconstruction unit 60 is also connected to a data collection buffer (buffer) 64. The data collection buffer 26 is connected to the data collection unit 26 of the scanning gantry 2. The data collected by the data collection unit 26 is input to the image reconstruction unit 60 via the data collection buffer 64.
[0032]
The image reconstruction unit 60 performs image reconstruction using the transmitted X-ray signal, that is, the projection data collected through the data collection buffer 64. The storage unit 66 is also connected to the image reconstruction unit 60. The storage unit 66 stores the projection data collected in the data collection buffer 64, the reconstructed tomographic image information, and a program for realizing the functions of the present apparatus.
[0033]
A display device 68 and an operation device 70 are connected to the image reconstruction unit 60, respectively. The display device 68 displays tomographic image information and other information output from the image reconstruction unit 60. The operation device 70 is operated by an operator, and inputs various instructions and information to the image reconstruction unit 60. The operator uses the display device 68 and the operation device 70 to interactively operate the apparatus.
[0034]
The image processing device 40 is connected to the storage unit 66 of the operation console 6 via the storage unit 44 by communication means (not shown). The image processing device 40 is provided on a console independent of the operation console 6, transfers the reconstructed tomographic image information and the like stored in the storage unit 66 to the storage unit 44, and transmits the image processing unit 41. Performs image processing. Here, the image processing unit 41 is configured by, for example, a computer.
[0035]
A display device 42 and an operation device 43 are connected to the image processing unit 41, respectively. The display device 42 displays tomographic image information output from the image processing unit 41 and other information. The operation device 43 is operated by an operator and inputs various instructions and information to the image processing unit 41. The operator uses the display device 42 and the operation device 43 to interactively operate the apparatus.
[0036]
FIG. 2 is a functional block diagram of the image processing device 40. The image processing device 40 has tomographic image information 200 from the operation console 6, and further has a vertical tomographic image information generating means 210, a region of interest setting means 220 serving as an extracting means, a threshold value means 231, an area expanding means 232, and a fixing means. 240, a function of a smoothing means 230 serving as an image processing means, and a thrombus evaluation means 250.
[0037]
The tomographic image information 200 is tomographic image information of a continuous axial section of the subject 1 transferred from the storage unit 66 to the storage unit 44. Here, the vertical tomographic image information generating means 210 calculates and generates a vertical tomographic image that intersects perpendicularly with the blood flow direction of the blood vessel in the tomographic image from the tomographic image information 200. Thus, in the blood vessel in the vertical tomographic image, the blood flow always flows in a direction perpendicular to the vertical tomographic plane, and the blood vessel cross-section is substantially circular.
[0038]
The region-of-interest setting means 220 sets an image region to be subjected to the arithmetic processing when performing the arithmetic processing of the image described later. In this setting, a region of interest (ROI; also referred to as Region Of Interest) is set on the tomographic image displayed on the display device 42, and various calculations are performed on pixels in this region. The region of interest has a circular region, and the position and size on the tomographic image are determined by inputting the center and radius of the circle from the operation device 43. The resetting unit stores the set region of interest in the storage unit 44 and sets the same region of interest on different tomographic images.
[0039]
The threshold means 231 receives a threshold value from the operation device 43 of the image processing device 40, determines a pixel value exceeding or not exceeding the threshold value, extracts a region of interest in which the pixel value exists, and displays the region of interest on the display device 42. . The threshold means 231 is effectively used to identify a region in the tomographic screen where the pixel values differ greatly. On the other hand, when an area having a small difference in pixel value in the tomographic screen is identified by the threshold unit 231, the boundary area is not determined due to noise or other reasons, and it is necessary to identify an accurate area. Difficulties may accompany. The threshold unit 231 outputs the extracted boundary information of the region of interest.
[0040]
The smoothing means 230 performs smoothing on the image information of the designated image area. The smoothing means 230 sets a neighborhood area called a mask around a certain pixel having tomographic image information, and sets all pixels in the mask. The values are added or weighted to obtain a new pixel value. The size of this mask is experimentally determined to be a size for smoothing density unevenness generated in an image of the thrombus, which will be described later, and has a size of approximately 3 × 3 pixel matrix. The smoothing unit 230 also includes a changing unit that allows the operator to change the size of the pixel matrix from the operation device 43 of the image processing device 40 in consideration of the individual difference of the subject 1.
[0041]
The region expanding unit 232 extracts pixels whose pixel values of the image within the region of interest are within the range of the upper limit and the lower limit specified by the operator, and extracts the image region. The region expanding means 232 extracts only a tissue portion having an intermediate CT value whose pixel value is within a finite range having a certain upper limit and a lower limit without extracting the extracted region within the image region. Used. On the other hand, in the case of a non-uniform tissue, for example, a thrombus where many density spots are present, it is difficult to extract only the tissue part because the pixel values of the tissue are scattered over a large range. .
[0042]
The determination means 240 performs circular arc approximation on the closed boundary area set on the tomographic screen of the display device 42, and generates, for example, a circular boundary having a minimum deviation from the boundary area. As a result, it is possible to extract a circular region that best fits the closed boundary region.
[0043]
Based on the extracted thrombus region, the thrombus evaluation unit 250 calculates the ratio of the area of the thrombus region or the ratio of the area of the blood vessel portion included in the thrombus region to the thrombus region obtained in time series. From the area of the area, quantitative information such as a temporal change of the thrombus is calculated.
[0044]
Next, before describing the operation of the image processing unit 41 according to the present embodiment, an outline of image collection by the operation console 6 and the scanning gantry 2 will be described. First, imaging of a subject by the X-ray CT system will be described with reference to the flowchart of FIG. The operator places the subject 1 on the cradle 31 of the scanning gantry 2 shown in FIG. 1 (Step S301). Then, the operator administers the contrast agent to the subject 1 (Step S302). At this time, the iodine-based contrast agent is mainly administered, for example, intravenously.
[0045]
Thereafter, the operator performs imaging of the subject (Step S303), and acquires projection data of the subject. Then, in the image reconstruction unit 60, tomographic image information of the subject is generated from the projection data and stored in the storage unit 66. Then, the tomographic image information in the storage unit 66 is transferred to the storage unit 44 of the image processing unit 41 by a transfer unit (not shown) (step S304). After that, the image processing unit 41 performs a thrombus extraction process on the transferred tomographic image information (step S305), and ends this process.
[0046]
Next, the thrombus extraction process performed by the image processing unit 41 will be specifically described with reference to the flowchart in FIG. From the tomographic image information 200 transferred from the operation console 6, the operator converts the image information of the diseased part drawn in the tomographic image, that is, the vertical tomographic plane orthogonal to the blood vessel in the vicinity of the aneurysm, into the vertical tomographic image generating means 210. (Step S401). FIG. 5A shows an example of a vertical tomographic image of the abdominal aorta when imaging the abdomen using an X-ray CT apparatus. In the vertical tomographic image, the blood vessels of the abdominal aorta are depicted in a substantially circular shape.
[0047]
Thereafter, the operator selects a bone region and a background region from the vertical tomographic image by the threshold means 231 and extracts a region of interest only of a soft tissue including a blood vessel and a thrombus existing around the blood vessel (step S402). FIG. 5B shows a region of interest consisting only of soft tissue. The background and bone parts of the spine are excluded from the region of interest.
[0048]
Thereafter, the operator extracts a blood vessel region from the region of interest only of the soft tissue (step S403). By administering the contrast agent, the blood vessel region is drawn with a high CT value, and can be extracted by the threshold means 231. In addition, since the effect of the contrast agent is transient, it is easy to extract only the blood vessel region by taking the difference between the image information of the vertical cross section after a predetermined time has elapsed. By this extraction, smoothing of a nearby region excluding a blood vessel region described later and extraction of only the thrombus portion are smoothly performed.
[0049]
Thereafter, the operator sets a nearby region by the region-of-interest setting means 220 around the blood vessel region extracted in step S403 (step S404). In this setting, a circular region of interest is set so as to sufficiently include the thrombus attached to the periphery of the blood vessel and to be included in the region of interest of the soft tissue extracted in step S402. FIG. 5 (C) illustrates a neighboring region set around the abdominal aorta in the soft tissue.
[0050]
FIG. 6 shows an enlarged view of only this vicinity region. As shown in FIG. 6 (A), this nearby region is composed of blood vessels, thrombus, and soft tissue. In the thrombus around blood vessels, there are density spots as indicated by black dots in FIG. Although a blood flow part exists inside the blood vessel, the blood flow part is excluded from the neighboring area by extracting the blood vessel area in step S403.
[0051]
Thereafter, the operator performs smoothing on the neighboring area set in step S404 using the smoothing means 230 (step S405). By this smoothing, the density unevenness existing in the thrombus region is smoothed, and becomes substantially uniform image information. Therefore, the threshold means 231 or the area expanding means 232 can be implemented. FIG. 6B schematically shows the smoothed region of interest. The density unevenness of the thrombus disappears by the smoothing, and becomes a uniform pixel area similar to the surrounding soft tissue.
[0052]
Thereafter, the operator determines whether or not the boundary between the smoothed thrombus portion and the surrounding tissue can be distinguished (step S406). If the boundary can be distinguished (step S406 negative), the operator sets the threshold value of the threshold means 231; The surrounding tissue is removed (step S407). If it cannot be distinguished (Yes at Step S406), the process proceeds to the next step without executing Step S407.
[0053]
Thereafter, the operator extracts only the approximate region of the thrombus portion from the smoothed region of interest by using the region expanding means 232 (step S408). Thereby, the approximate region of the thrombus portion is extracted. FIG. 6C schematically shows the approximate region of the thrombus extracted by the region expanding means 232. Due to the smoothing process or the like performed in step S405, the border of this approximate region is in a state in which the boundary with the surrounding soft tissue is not determined and varies.
[0054]
Thereafter, the operator performs arc approximation on the boundary of the edge of the approximate region using the determining means 240 (step S409), and determines the circular thrombus region. FIG. 6D schematically shows the circular thrombus region extracted by the determination means 240. The basis for performing the arc approximation is based on experimental and empirical facts that the cross section of the thrombus adhering around the blood vessel is circular.
[0055]
Thereafter, it is determined whether or not to extract a thrombus from a nearby different vertical tomographic plane (step S410). If a thrombus is to be extracted (Yes at step S410), the vertical tomogram generated at step S401 is determined. A nearby vertical tomographic plane is selected from the planes and displayed (step S411). Then, the process shifts to step S404 to set a region of interest in the display image. At this time, the already set region of interest can be used as it is by using the resetting means.
[0056]
If the thrombus portion is not extracted (No at Step S410), the thrombus portion extraction process is terminated, and the thrombus portion is evaluated from the acquired thrombus portion information (Step S412). In the evaluation of the thrombus portion, the area of the extracted thrombus region or the area ratio with the blood vessel region is calculated. Further, a change in the area of the thrombus region collected in time series, a change in the thrombus region before and after the operation, and the like are also calculated.
[0057]
As described above, in the present embodiment, a nearby region including a blood vessel in a vertical tomographic plane orthogonal to the blood vessel is extracted, a smoothing process is performed on this nearby region, and a region expanding process is performed on the smoothed region of interest. The approximate region of the thrombus is extracted by the following, and the circular region is extracted by the arc processing from the approximate region of the thrombus.Therefore, the approximate region of the thrombus is extracted using the region expanding process, and the approximate region is extracted from the approximate region. It is possible to extract an arc-shaped thrombus region with high accuracy, and thus to perform thrombus area evaluation and quantitative evaluation such as temporal change in thrombus area.
[0058]
【The invention's effect】
As described above, according to the present invention, a plurality of pieces of tomographic image information of a subject are acquired by an X-ray CT apparatus, and a plurality of pieces of vertical tomographic image information that intersects perpendicularly with a blood flow direction in a blood vessel are obtained from the tomographic image information. Is extracted from the image of the vertical tomographic image information, a region near the blood vessel including the blood vessel is extracted, the image of the nearby region is smoothed, and a thrombus adhering to the blood vessel is extracted from the smoothed image by the region expanding means. Since the approximate region of the thrombus is extracted and the edge of this approximate region is determined in an arc shape, the density unevenness present in the thrombus is smoothed, and the approximate region of the thrombus is extracted. The edge is further determined to be an arc shape, and a thrombus region with high accuracy can be extracted. As a result, a thrombus area can be evaluated, and a quantitative evaluation such as a temporal change in the thrombus area can be performed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the overall configuration of an X-ray CT system.
FIG. 2 is a functional block diagram of the image processing apparatus according to the embodiment;
FIG. 3 is a flowchart illustrating acquisition of tomographic image information according to the embodiment;
FIG. 4 is a flowchart illustrating a thrombus extraction process according to the embodiment;
FIG. 5 is a diagram showing extraction of a nearby region from a vertical tomographic image according to the embodiment;
FIG. 6 is a schematic diagram illustrating image processing of a nearby area according to the embodiment;
[Explanation of symbols]
1 Subject
2 scanning gantry
6 Operation console
20 X-ray tube
22 Collimator
24 Detector array
26 Data Collection Unit
28 X-ray controller
30 Collimator controller
31 cradle
34 Rotating part
36 Rotation controller
40 Image processing device
41 Image processing unit
42 Display
43 Operating device
44 Memory
60 Image reconstruction unit
62 Control interface
64 data collection buffer
66 storage unit
68 Display device
70 Operating device
200 tomographic image information
210 tomographic image generation means
210 Vertical tomographic image generation means
220 region of interest setting means
230 smoothing means
231 threshold means
232 area expansion means
240 Confirmation means
250 thrombus evaluation means

Claims (9)

A plurality of tomographic image information of the subject is acquired by an X-ray CT apparatus, and a plurality of vertical tomographic image information that intersects perpendicularly with a blood flow direction in a blood vessel is generated from the tomographic image information;
Extracting the vicinity region of the blood vessel including the blood vessel from the image of the vertical tomographic image information,
Smoothing the image of the neighborhood,
Extract an approximate region of a thrombus attached to the blood vessel from the smoothed image,
Determining the edge of the approximate region in an arc shape,
A method for extracting an image of a thrombus portion, characterized in that: An image processing apparatus that acquires a plurality of pieces of tomographic image information of a subject from an X-ray CT apparatus and generates a plurality of pieces of vertical tomographic image information that intersects perpendicularly with a blood flow direction in a blood vessel from the tomographic image information,
Extracting means for extracting a region near the blood vessel including the blood vessel from the image of the vertical tomographic image information,
Smoothing means for smoothing the image of the neighboring area,
Region expanding means for extracting a region having a pixel value in a specified range from the smoothed image;
Determining means for determining the edge of the approximate area in an arc shape,
An image processing apparatus comprising: The image processing apparatus according to claim 2, wherein the extraction unit includes a threshold unit that extracts an image area having a pixel value exceeding a threshold value or a pixel value not exceeding the threshold value. The image processing apparatus according to claim 2, wherein the extraction unit includes a region of interest setting unit that sets a region of interest. 5. The apparatus according to claim 4, wherein the region of interest setting unit stores a range of the region of interest and resets the region to a plurality of tomographic images close to a tomographic image of the vertical tomographic image information. An image processing apparatus according to claim 1. The image processing apparatus according to any one of claims 2 to 5, wherein the smoothing unit includes a spatial filter having a size of a mask area for smoothing density unevenness in the thrombus area. The image processing apparatus according to claim 6, wherein the spatial filter includes a changing unit that changes a size of a mask area. The image processing apparatus according to claim 2, wherein the determination unit approximates the edge with a circular arc. An X-ray CT apparatus that irradiates the subject with an X-ray beam, collects projection data of the subject, and obtains tomographic image information of the subject by image reconstruction of the projection data;
Transfer means for transferring the tomographic image information of the X-ray CT apparatus;
From the tomographic image information transferred by the transfer means, an image processing device that generates a plurality of vertical tomographic image information that intersects perpendicularly to the blood flow direction in the blood vessel,
An X-ray CT system comprising:
The image processing apparatus includes: an extraction unit configured to extract a region near the blood vessel including the blood vessel from an image of the vertical tomographic image information; a smoothing unit configured to smooth an image of the vicinity region; and the smoothed image. From, region expansion means for extracting a region having a pixel value of the specified range, and a determination means for determining the edge of the thrombus region in an arc,
An X-ray CT system comprising:

Images