JP4360994B2 - Density analysis method, computer program implementing density analysis method, and density analysis system - Google Patents

Description

  The present invention relates to a density analysis method for analyzing the density of a subject using imaging data obtained by an X-ray CT apparatus, a computer program that implements the density analysis method, and a density analysis system.

  In an X-ray CT apparatus, image reconstruction processing is performed on imaging data obtained by detecting the amount of X-rays that are absorbed and attenuated when X-rays emitted from an X-ray source such as an accelerator or an X-ray tube pass through the subject. To generate a two-dimensional cross-sectional image or a three-dimensional image of the subject. The absorption / attenuation of X-rays when passing through the subject correlates with the density of the subject in the portion where the X-rays are transmitted. That is, the CT value in a pixel constituting an image of the subject as a rectangular small region by the X-ray CT apparatus has a value correlated with the density of the portion of the subject corresponding to each pixel. For this reason, analysis of a subject with respect to density is performed using imaging data obtained by an X-ray CT apparatus. For example, a technique for evaluating the battery characteristics by obtaining the density distribution of the active substance in the battery from a tomographic image captured by an X-ray CT apparatus and checking the quality of the battery at the time of manufacture and use is an example (Patent Literature). 1). In addition, for example, Patent Documents 2 to 4 disclose techniques for analyzing the density of a subject from image data obtained by an X-ray CT apparatus.

Japanese Patent No. 3125120 JP-A-7-134088 JP-A-8-327525 Japanese Patent Laid-Open No. 10-227734

  The usefulness of density analysis using an X-ray CT apparatus is increasing, and the demand for high-accuracy density analysis for analyzing even finer density differences is increasing. For example, in the evaluation of battery characteristics based on the density distribution of the active substance in the battery, it is useful to analyze the difference in the density distribution of the active substance after discharging or charging. Density analysis is required.

  However, the X-ray CT apparatus has a resolution. The resolution in the current X-ray CT apparatus is generally about 2% of the density of the substance constituting the subject, but the influence of noise increases in the vicinity of the resolution. For this reason, significant density analysis cannot be performed in the vicinity of the resolution, and in reality the demand for high-precision density analysis cannot be met.

  The present invention has been made against the background of such circumstances, and a first object of the present invention is to provide a density analysis method that enables significant density analysis even in the vicinity of the resolution in an X-ray CT apparatus. A second object is to provide a computer program that implements the density analysis method, and a third object is to provide a density analysis system for executing such a density analysis method.

Furthermore, the present invention provides a density analysis method for analyzing the density of the subject based on imaging data obtained by imaging the subject with an X-ray CT apparatus.
A process of acquiring at least two or more imaging data for the same subject by the X-ray CT apparatus at different times, and the density analysis for a plurality of density analysis target parts set in each of the plurality of imaging data Positions of the plurality of imaging data obtained in the imaging data acquisition process after the processing step of setting a density inspection region composed of a plurality of pixels for each target part and the processing step of setting the density inspection region A processing process for performing matching, a processing process for obtaining an average value of each density value of a plurality of pixels in the density inspection region set in the processing process, and an average value of the density values obtained in the processing process for the density analysis target Including a processing step of obtaining a density difference between the plurality of imaging data and corresponding density analysis target parts as the density value of the part. Density analytical method to disclose.

  For the second purpose, in the present invention, an imaging data reading function for reading imaging data acquired by the X-ray CT apparatus and an imaging data reading function for a computer program in which the density analysis method as described above is implemented. An alignment function for aligning a plurality of read imaging data, a plurality of density analysis target parts set in each of the plurality of imaging data, and a plurality of density analysis target parts for each density analysis target part A density inspection area setting function for setting a density inspection area composed of pixels of the density, a density calculation function for obtaining an average value of each density value of a plurality of pixels in the density inspection area set by the density inspection area setting function, And the average value of the density values obtained by the density calculation function is the density value of the density analysis target part, and the plurality It is intended to include density difference calculation function for calculating the density difference for between corresponding density analysis target part among the imaging data.

  For the third object, the present invention provides a density analysis system used in a density analysis method for analyzing the density of the subject based on imaging data obtained by imaging the subject with an X-ray CT apparatus. And a density analyzer for executing the density analysis method as described above.

  In the present invention, in the density analysis system as described above, the density analyzer includes a program storage device that stores the computer program as described above, and an arithmetic device that executes the computer program read from the program storage device. It is supposed to consist of

  In the present invention, a density inspection region composed of a plurality of pixels is set around the density analysis target region, and an average value of each density value of a plurality of pixels included in the density inspection region is obtained, and the density value is obtained. The representative density value in the analysis target part is used. By doing in this way, the influence of the noise which arises at random for every pixel can be canceled, and it can reduce significantly. As a result, the accuracy of density analysis can be greatly increased, and significant density analysis can be performed even in the vicinity of the resolution in the X-ray CT apparatus.

  Hereinafter, preferred embodiments for carrying out the present invention will be described. FIG. 1 shows a flow of processing in the density analysis method according to the first embodiment, and FIG. 2 schematically shows a state of imaging of a subject by the X-ray CT apparatus in the processing. The present embodiment is an example in the case of analyzing a temporal change in density in the same subject, for example, a density difference before and after processing when some kind of processing is performed on the subject. As such an example, there is a density difference analysis before and after discharging or charging in a battery that repeatedly discharges and charges, for example.

  An X-ray CT apparatus 2 for imaging a subject 1 is composed of an accelerator, an X-ray tube, etc., and an X-ray source 2a that irradiates X-rays 2x, and an X-ray detector 2b that detects X-rays 2x from the X-ray source 2a. , And a turntable 2c on which the subject 1 is placed and rotated. The X-ray detector 2b detects X-rays 2x transmitted through the subject 1 or passing around the subject 1 while irradiating the subject 1 with X-rays 2x while rotating the turntable 2c. Acquire imaging data.

  The subject 1 is imaged by the X-ray CT apparatus 2 at time T1, and the imaging data 101 of the subject 1 is acquired (process 1001). The imaging data 101 is imaging data of the subject 1 before any processing is performed. Then, a predetermined process is performed on the subject 1 (process 1002). This process is discharging or charging if the subject 1 is a battery that repeatedly discharges and charges. At time T2 after processing, the subject 1 is newly imaged by the X-ray CT apparatus 2 to acquire imaging data 102 (processing 1003). The imaging data 101 and 102 are obtained by separately imaging the subject 1 at different times T1 and T2. For this reason, the position of the subject 1 in the image generated by reconstructing the imaging data 101 and 102 is usually shifted as shown in FIG. Accordingly, the image data 101 and 102 are aligned, and more specifically, the image data 101 and 102 are aligned to align the position of the subject 1 (process 1004).

  The alignment of the imaging data can be performed based on the geometric shape of the subject 1, can be performed based on the center of gravity and the principal moment of inertia of the subject, and the shape error of the imaging data 101 and 102 It can also be performed by a method of minimizing the error. Hereinafter, alignment based on the geometric shape of the subject 1 will be described. An image of an example of alignment based on the geometric shape is shown in FIG. In order to align the imaging data 101 and 102 based on the geometric shape, a reference point (reference origin) in the subject 1 and an image coordinate system of the characteristic geometric shape of the subject 1 An inclination angle (rotation angle) with respect to 4 needs to be obtained. In one method for obtaining these, if the subject 1 has a contour with a crossing straight line, it is used as a characteristic geometric shape and the corresponding position between the imaging data 101 and the imaging data 102. , Two intersecting straight lines 8, 8 and straight lines 8 ', 8' are defined. In order to define the two straight lines 8 and 8 intersecting the imaging data 101, the vicinity of the boundary between the data portion representing the subject 1 and the data portion representing the air around the subject 1 in the imaging data 101 is displayed on the image. A method can be used in which a plurality of points are measured and a straight line that best matches a plurality of points obtained by the measurement is obtained by calculation. If the straight lines 8 and 8 can be defined, the intersection point is obtained and set as the reference origin 5. Further, the rotation angle is obtained as the angle formed by the subject 1 with respect to the image coordinate system 4 from the direction vector of the straight line 8. Similarly, for the imaging data 102, straight lines 8 ′ and 8 ′ are defined, and the intersection point thereof is set as the reference origin 5 ′, and the rotation angle of the subject 1 is obtained from the direction vector of the straight line 8 ′.

  As another method for obtaining the reference origin, circles 7 and 7 'are defined at corresponding positions of the imaging data 101 and the imaging data 102 as shown in the example shown in FIG. A method using the reference origin is possible. When the reference origin and the rotation angle are obtained as described above, the image data 101 and the image data 102 are subjected to affine transformation (primary transformation) and aligned. FIG. 4 shows an example of imaging data 101 ′ and imaging data 102 ′ after affine transformation.

  Here, the subject may not have a geometric shape that serves as an alignment index. In the case of such a subject, an alignment index body having a geometric shape such as a straight line, a flat surface, or a cylindrical surface that can be easily used as an alignment index is attached to the subject to perform imaging. An example is shown in FIG. In the example of FIG. 5, the contour of the subject 1 is composed of an arc-shaped portion and a jagged shape portion, and it is difficult to use these as an index of the rotation angle. Therefore, an alignment index body 9 having a square cross-sectional shape is attached, and this is imaged together with the subject 1. For such a subject 1, the reference origin is obtained using the arc-shaped contour portion. That is, a plurality of points are measured along the arc-shaped contour portion of the subject 1, and the reference origins 5 and 5 ′ are obtained as the center points of the arcs 10 and 10 ′ that best fit the plurality of points. On the other hand, the rotation angle of the subject 1 is obtained from the alignment index body 9. That is, straight lines 8 and 8 ′ are obtained in the same manner as described with reference to FIG. 3 for the alignment index body 9, and the rotation angle of the subject 1 is obtained from the straight lines 8 and 8 ′.

  The X-ray CT apparatus 2 can also obtain a three-dimensional shape image of the subject 1 by stacking two-dimensional cross-sectional images of the subject 1 in a direction perpendicular thereto. When the X-ray CT apparatus 2 irradiates a cone-shaped X-ray (cone beam) instead of the fan-shaped X-ray 2x (fan beam) as in the example of FIG. A shape image can be obtained. When obtaining three-dimensional imaging data for the subject 1, the three-dimensional imaging data is aligned. FIG. 6 shows such an example. For the subject 1 having a three-dimensional shape as in the example of FIG. 6, first, a plurality of points on the upper end surface of the subject 1 in the imaging data 101 are measured on the image, and a plane 12 that best fits these points is obtained. Ask. Then, a plurality of points on the inner surface or outer surface of the subject 1 are measured on the image, and the cylindrical surface 11 that best fits these points is obtained. Then, a reference origin is obtained as an intersection 11p between the central axis 11a of the cylindrical surface 11 and the plane 12. One axis of the imaging data 101 is set as the central axis 11a of the cylindrical surface 11, and the remaining two axes are determined by using the alignment index body 9 attached to the subject 1 and rotated from these three axes. Find the angle. Similarly, for the imaging data 102, the plane 12 ′ and the cylindrical surface 11 ′ are obtained, and then the reference origin is obtained as the intersection 11p ′ of the central axis 11a ′ of the cylindrical surface 11 ′ and the plane 12 ′, and the center of the cylindrical surface 11 ′ is obtained. The rotation angle is obtained from one axis obtained as the axis 11a ′ and the remaining two axes obtained by using the alignment index body 9 attached to the subject 1.

  When the alignment of the subject 1 is completed as described above, a density inspection region is set and arranged for each of the imaging data 101 ′ and 102 ′ (processing 1005). The density inspection region is a region that defines a range of spread in which CT values are sampled when acquiring CT values corresponding to the density of a substance constituting the subject 1 from imaging data. The density inspection area is set by setting an appropriate number of pixels centered on the density analysis target part for each of a plurality of CT value acquisition target parts (density analysis target parts) set in the imaging data. It is done by setting every. The appropriate number of pixels, that is, the size of the density inspection area correlates with the magnitude of noise in the imaging data, and the magnitude of the noise is determined based on the type and size of the constituent material (subject material) and X It depends on the energy condition of the wire. Accordingly, the size of the density inspection region is determined in consideration of the above parameters at the time of density analysis. In one example, when the imaging data is two-dimensional, the size of the density analysis target region is set to 4 pixels of 2 × 2 to 9 pixels of 3 × 3 (pixel size is, for example, about 200 μm), and the surroundings are centered on this. Hundreds to thousands of pixels are set as a density inspection region in a state adjacent to the. Such density inspection regions may overlap each other depending on the set interval of the density analysis target parts.

  FIG. 7 shows an example in which density inspection regions are set and arranged in the imaging data 101 ′ and 102 ′ after the primary conversion in FIG. In the example of the figure, the density inspection regions 3 of the plurality of density analysis target parts are made the same size. Thus, if each density inspection area 3 is set to the same size, the density inspection area 3 is arranged at the same coordinate position of each of the imaging data 101 ′ and 102 ′. The density change amount between the imaging data 101 and the imaging data 102 is calculated on the two-dimensional cross-sectional image or the three-dimensional shape image based on the difference between the imaging data 101 ′ and 102 ′ of the averaged CT value in each pixel. It can be obtained as a distribution.

  Here, in the above example, the density inspection region 3 is set / arranged after positioning the subject, but the setting / arrangement of the density inspection region 3 is determined in advance, and the setting / arrangement is determined. It is also possible to adopt a method of adapting to each of the imaging data 101 and the imaging data 102 by primary conversion. FIG. 8 shows an image in the case where the density inspection region 3 whose setting and arrangement are determined in advance is adapted to each of the imaging data 101 and the imaging data 102. Since the CT value is expressed as digital data, when the image is subjected to primary conversion, a truncation error occurs due to being expressed in a finite number of digits, and the imaging data 101 and the imaging data 101 ′ or the imaging data 102 Some errors are included between the imaging data 102 '. This error can have an effect on small density changes. Considering this, it can be said that the method of adapting the predetermined density inspection region of the setting / array to the imaging data is more effective for improving the accuracy of the density analysis.

  When the imaging data is three-dimensional, the density inspection region is also three-dimensional. FIG. 9 shows an example of setting and arrangement of the three-dimensional density inspection region 3 in the three-dimensional imaging data. In this way, by setting and arranging the three-dimensional density inspection region 3 in the three-dimensional imaging data, a three-dimensional distribution (spatial distribution) of density change can be obtained.

  FIG. 10 shows another example of the shape of the density inspection region. (A) is an example of the density inspection region 3a having an arc shape, (b) is an example of the density inspection region 3b having a partial fan shape, and (c) is an example of the density inspection region 3c having a spherical shape. . Thus, the density inspection region can be set in an arbitrary shape.

  When the setting of the density inspection area is completed, the average density is calculated for each density inspection area 3 (process 1006). The average density is calculated by the following formula.

ここで、ρ_ｉバーは撮像データ１０１´または撮像データ１０２´に設定した個々の密度検査領域における平均密度、ｉ（＝１，２…，Ｍ）は撮像データ１０１´、１０２´それぞれに設定した密度検査領域の数、ρ_ｉｊは各密度検査領域に含まれる個々の画素におけるＣＴ値を密度に変換した値、ｊ（＝１，２…，Ｎ）は各密度検査領域に含まれる画素の数である。

Here, ρ _i bar is the average density in each density inspection region set in the imaging data 101 ′ or imaging data 102 ′, and i (= 1, 2,..., M) is set in the imaging data 101 ′ and 102 ′, respectively. The number of density inspection regions, ρ _ij is a value obtained by converting the CT value of each pixel included in each density inspection region into a density, and j (= 1, 2,..., N) is the number of pixels included in each density inspection region. It is.

  Conversion from the CT value to the density value is based on the following equation.

ここで、ρは密度、ｘはＣＴ値であり、ａとｂは以下の式により求められる。

Here, ρ is the density, x is the CT value, and a and b are obtained by the following equations.

（３）式と（４）式において〈〉で囲まれた値は平均値を表す。なお必要に応じて分散あるいは標準偏差を計算することもできる。分散と標準偏差は下記の（５）、（６）式で計算する。

In the expressions (3) and (4), the value enclosed in <> represents an average value. Note that the variance or standard deviation can be calculated as necessary. The variance and standard deviation are calculated by the following equations (5) and (6).

  When the calculation of the average density is finished, a density difference is obtained between the corresponding density inspection areas of the imaging data 101 ′ and the imaging data 102 ′ (processing 1007). The density difference is calculated by the following formula.

ここで、（ρ_ｉバー）_Ａは撮像データ１０１´に設定した密度検査領域の内のｉ番目の密度検査領域における平均密度、（ρ_ｉバー）_Ｂは撮像データ１０２´に設定した密度検査領域の内のｉ番目の密度検査領域における平均密度、Δρ_ｉバーはこれらの密度差である。

Here, (ρ _i bar) _A is an average density in the i-th density inspection region in the density inspection region set in the imaging data 101 ′, and (ρ _i bar) _B is a density inspection region set in the imaging data 102 ′. The average density in the i th density inspection region, Δρ _i bar, is the difference between these densities.

  By performing the above process for all of the plurality of density inspection regions set in the respective imaging data 101 ′ and 102 ′, the local density temporal change amount (change amount before and after the process) for the subject 1 is obtained. Can do. Creating a two-dimensional or three-dimensional distribution map of the density variation by using the obtained density variation as a density value (representative density value) at the center coordinates of each density inspection region and connecting the density values with contour lines. Can do. An example of a two-dimensional distribution diagram of the density variation is shown in FIG. Further, by integrating the density change amount in each density inspection region over the whole of the plurality of density inspection regions, the temporal change amount of the weight of the subject can also be calculated.

  In the above example, the average density is obtained for the density inspection region 3 set in the imaging data 101 ′ and 102 ′ after the alignment, and the difference is obtained for the average density. It is also possible to obtain a density difference for each corresponding pixel of each of the imaging data 101 ′ and 102 ′ and obtain an average value for each density inspection region 3 for the density difference. Moreover, although the above example was a case where there were two imaging data, it is not restricted to this, The same process is possible also when acquiring three or more imaging data.

  As described above, in the present invention, a density inspection region including an appropriate number of pixels is set around the density analysis target region, and each density value obtained from the CT value of each pixel included in the density inspection region is set. The average value is obtained from the above, and this is set as the representative density value in the density analysis target part. By doing in this way, the influence of the noise which arises at random for every pixel can be canceled, and it can reduce significantly. As a result, the accuracy of density analysis can be greatly increased, and significant density analysis can be performed even in the vicinity of the resolution in the X-ray CT apparatus.

  Such a density analysis method according to the present invention is particularly effective when the density difference of the analysis target is very small as in the analysis of the density change before and after the processing in the same specimen as described in the above embodiment. For general density analysis, the high accuracy of the analysis is useful.

  FIG. 12 shows the flow of processing in the density analysis method according to the second embodiment. The present embodiment relates to a density analysis on the premise that it is applied to a case where a product to be mass-produced is used as an object and a product distribution is evaluated by analyzing a difference in density distribution in each product. In processing 2001, the imaging data 201 of the subject 1 is acquired by the X-ray CT apparatus 2 in the configuration in FIG. In the subsequent process 2002, the imaging data 202 is acquired for the subject 1a having the same shape as the subject 1 (the same product as the subject 1). The following processes 2003 to 2006 correspond to the processes 1004 to 1007 in FIG. 1, and the processes in each are the same as those described with reference to FIG.

  Hereinafter, an embodiment of a computer program that implements the density analysis method according to the present invention will be described. Examples of screens displayed on the display device of the computer when the computer program according to the embodiment is executed are shown in FIGS. The present embodiment is a case of a computer program that implements the density analysis method according to the first embodiment. The computer program includes an imaging data reading function, functions for each process described above with reference to FIG. 1, that is, a function for positioning (alignment function), and a function for setting a density inspection region (density inspection). An area setting function), a function for obtaining an average density for each density inspection area (density calculation function), and a function for obtaining a density difference between a plurality of imaging data (density difference calculation function). Each of these functions will be described below.

  FIG. 13 is an example of the screen 14 displayed in the process of reading the imaging data obtained in the processing 1001 and the processing 1003 in FIG. 1 by the imaging data reading function, and the imaging obtained by imaging with the X-ray CT apparatus 2. A state in which data 101 and image data 102 are read into a computer and respective images are displayed is shown.

  FIG. 14 shows an example of a screen in a state where the alignment function is called and the processing 1004 in FIG. 1 is performed. That is, setting for alignment and screen transition when imaging data is primarily converted after alignment are shown. The alignment function includes means for measuring the characteristic geometric shape of the subject or the alignment index body attached to the subject and means for performing alignment processing based on the geometric shape. In the example shown in the figure, these means are collectively displayed as a tool 15 on the screen. In the example shown in the figure, a geometric shape such as a straight line, a circle, an arc, a plane, or a cylindrical surface can be measured. In addition, it may be possible to measure a cone or a sphere. Since the contents of the processing by the alignment function are the same as described above, description thereof is omitted here.

  FIG. 15 shows the transition of the screen in a state where the density inspection region setting function (density inspection region arrangement function) is used to set the density inspection region in the imaging data 101 ′ and the imaging data 102 ′. The density inspection area setting function includes means for determining the shape of the density inspection area, means for determining the size of the density inspection area, and means for determining the arrangement of the density inspection area, which are collectively displayed as the tool 16 on the screen. Is displayed. In the example of the figure, a straight line, an arc, an arbitrary curve, a rectangle, a circle, a polygon, a rectangular parallelepiped, a sphere, and the like can be specified as the shape of the density inspection region. For the density inspection region arrangement determining means in the density inspection region setting function, a method for determining the arrangement with reference to the screen 17 or a method for determining the arrangement by a mathematical formula can be applied. Further, the density inspection region arrangement determining means includes a preview function for confirming the arrangement state by reflecting the density inspection regions arranged on the screen 17 in the imaging data 101 ′ and 102 ′. For the density inspection region size determination means in the density inspection region setting function, a method for determining the size of the density inspection region on the screen 17 by an input means such as a mouse or a method for inputting the size of the density inspection region numerically is applied. Can do. The density inspection area size once determined can also be changed. FIG. 16 shows an example of a screen when the size of the density inspection region in the state of FIG. 15 is enlarged and corrected.

  The primary conversion of the density inspection area can be selected at the time of alignment, and the same function can be used even when it is selected. When the size and arrangement of the density inspection area are specified on the screen 17 of the tool 16, a state in which primary conversion corresponding to the result obtained at the time of alignment is performed on the density inspection area is displayed on the imaging data 101 and 102. . The state of this processing is shown in FIG.

  FIG. 18 shows the transition of the screen when the density calculation function (density measurement function) is performing the density calculation process. The density calculation function includes means for selecting imaging data for density calculation, means for executing density calculation, and means for displaying calculation results, which are collectively displayed as a tool 18 on the screen.

  FIG. 19 shows the transition of the screen when the density difference calculation function (density difference calculation function) is performing the density difference calculation process. The density difference calculation function includes means for selecting imaging data to be subjected to density difference calculation, means for executing density difference calculation, and means for displaying the calculation result, and these are collectively displayed as a tool 19 on the screen. The In the illustrated example, the density difference distribution diagram 20 is also displayed as the density difference calculation result.

  Here, in the above embodiment, the processing that is equally performed on the imaging data 101 and the imaging data 102 is performed on both imaging data at the same time. You can also

  By using the computer program as described above, the density analysis method according to the present invention can be advanced more easily and efficiently.

  Next, a preferred embodiment of a density analysis system for implementing the density analysis method according to the present invention will be described. FIG. 20 shows the configuration of the density analysis system according to the first embodiment. The density analysis system according to the present embodiment includes an X-ray CT apparatus 2 that images a subject, an image reception apparatus (imaging data reception apparatus) 21 that receives an image (imaging data) captured by the X-ray CT apparatus 2, and a received image. An image storage device (imaging data storage device) 22 for storing an image, a density analysis device 23 for calling an image stored in the image storage device 22 and executing a density analysis, and an analysis result by the density analysis device 23 are stored. It comprises a density analysis result storage device 24 and a display device 25 for displaying images and density analysis processes.

  FIG. 21 shows the configuration of the density analysis system according to the second embodiment. The density analysis system in this embodiment is basically the same as that in the first embodiment. The difference is that a device comprising a density analysis program storage device 26 and a computing device (computer) 27 is provided as an element corresponding to the density analysis device 23. That is, in the density analysis system of this embodiment, the density analysis program storage device 26 and the calculation device 27 constitute a “density analysis device”, and the density analysis program stored in the density analysis program storage device 26 is executed by the calculation device 27. By doing so, density analysis will be performed. The computer program described above is used for the density analysis program.

  The present invention greatly increases the accuracy of density analysis using imaging data obtained by an X-ray CT apparatus and enables significant density analysis even in the vicinity of the resolution of the X-ray CT apparatus, and is required in various fields. Can be widely applied to density analysis.

It is a figure which shows the flow of the process in the density analysis method by 1st Embodiment. It is a figure which shows typically the mode of the imaging of the subject by X-ray CT apparatus. It is a figure which shows the image of the example of the alignment based on a geometric shape. It is a figure which shows the example of the imaging data after primary conversion. It is a figure which shows the example of the imaging data which attached the index body for alignment to the subject, and imaged. It is a figure which shows the image of the example of alignment about three-dimensional shape imaging data. FIG. 5 is a diagram illustrating an example in which density inspection regions are set and arranged in imaging data after the primary conversion in FIG. 4. It is a figure which shows the image in the case of adapting the density inspection area | region which decided and arrangement | positioning beforehand to imaging data. It is a figure which shows the example of the setting and arrangement | positioning of the three-dimensional density inspection area | region in three-dimensional imaging data. It is a figure which shows the other example about the shape of a density inspection area | region. It is a figure which shows the example of the two-dimensional distribution map of density variation. It is a figure which shows the flow of the process in the density analysis method by 2nd Embodiment. It is a figure which shows the example of the screen displayed in the process in which imaging data is read by the imaging data reading function. It is a figure which shows the transition of the screen in the state which is performing the alignment process by the alignment function. It is a figure which shows the transition of the screen in the state which is performing the process which sets a density inspection area | region with a density inspection area | region setting function. It is a figure which shows the example of the screen at the time of carrying out expansion correction of the size of the density inspection area | region in the state of FIG. It is a figure which shows the mode of a process at the time of selecting primary conversion of a density inspection area | region at the time of alignment. It is a figure which shows the transition of the screen in the state which is performing the density calculation process with a density calculation function. It is a figure which shows the transition of the screen in the state which is calculating the density difference with the density difference calculation function. It is a figure which shows the structure of the density analysis system by 1st Embodiment. It is a figure which shows the structure of the density analysis system by 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Subject 2 X-ray CT apparatus 3 Density inspection area 101 Imaging data 102 Imaging data

Claims (4)

In a density analysis method for analyzing the density of the subject based on imaging data obtained by imaging the subject with an X-ray CT apparatus,
A process of acquiring at least two or more imaging data for the same subject at different times by the X-ray CT apparatus, and the density analysis for a plurality of density analysis target parts set for each of the plurality of imaging data Positions for a plurality of imaging data obtained in the imaging data acquisition process after a processing process for setting a density inspection area composed of a plurality of pixels for each target part and a processing process for setting the density inspection area A processing process for performing matching, a processing process for obtaining an average value of each density value of a plurality of pixels in the density inspection region set in the processing process, and an average value of the density values obtained in the processing process for the density analysis target Including a processing step of obtaining a density difference between the plurality of imaging data and corresponding density analysis target parts as the density value of the part. Density analysis how to. A computer program that implements the density analysis method according to claim 1,
An imaging data reading function for reading imaging data acquired by the X-ray CT apparatus, an alignment function for aligning a plurality of imaging data read by the imaging data reading function, and each of the plurality of imaging data With respect to a plurality of density analysis target parts to be set, a density inspection area setting function for setting a density inspection area composed of a plurality of pixels around each density analysis target part is set by the density inspection area setting function. A density calculation function for obtaining an average value of each density value of a plurality of pixels in the density inspection region, and an average value of the density values obtained by the density calculation function as the density value of the density analysis target part, Corresponding density between multiple imaging data It includes a density difference calculation function to calculate the density difference between the analysis target parts Computer programs that butterflies. In a density analysis system used in a density analysis method for analyzing the density of the subject based on imaging data obtained by imaging the subject with an X-ray CT apparatus,
A density analysis system comprising a density analysis apparatus for executing the density analysis method according to claim 1. The density analysis apparatus according to claim 3, wherein the density analysis apparatus includes a program storage device that stores the computer program according to claim 2, and an arithmetic device that executes the computer program read from the program storage device. system.

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