JPS61226022A - Image processor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a tomographic imaging device (hereinafter abbreviated as a CT scanner) that takes a tomographic image of a specific cross section of an object to be inspected, and particularly relates to a tomographic imaging device (hereinafter abbreviated as a CT scanner). The present invention relates to an image processing apparatus that calculates the density in a photographed tomographic plane of an object to be inspected from image data obtained.

[Technical use of the invention and its problems] A CT scanner irradiates a specific cross section of an object to be inspected with radiation from multiple directions.
Transmission data is obtained by measuring these transmission doses,
A tomographic image of a specific cross section of the object to be inspected is obtained from this transmission data, and from the image data at each slice position obtained by this tomography, various information regarding the measurement of the upper object to be inspected, such as Information such as the dimensions, cross-sectional shape, presence or absence of defects of the object to be inspected, and tissue distribution of the human body etc. can be obtained. Therefore, the above CT scanner is widely used for industrial or medical purposes.

By the way, if it is possible to determine the density in the photographed tomographic plane of the object to be inspected from the image data obtained by the above-mentioned CT scanner, it will be much more useful, especially for the composition analysis of industrial products and their product materials, and the management of industrial products and materials. You can expect the following effects. BACKGROUND ART Conventionally, a method for determining density from image data has not been established because the tissues of living organisms such as the human body are composed of various elements, and the composition ratio varies from tissue to tissue. However, when CT scans are used for industrial purposes, the object to be inspected is made of relatively simple materials of one or several types, so it has been desired to develop a method for determining density.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and its purpose is to perform non-contact, non-destructive imaging of a test object from a tomographic image obtained by irradiating the test object with radiation. An object of the present invention is to provide an image processing device capable of calculating density within a tomographic plane.

[Summary of the Invention] The present invention performs image reconstruction processing on radiation absorption data obtained by irradiating a specific cross section of an object to be inspected, obtains image data regarding the specific cross section, and Information regarding the material in the cross section is inputted by the input means, information regarding the density calculation is obtained from the storage section according to the information inputted by the input means, and the information regarding the density calculation obtained from the storage section and the image data are used. This method calculates the density within a specific cross section of the object to be inspected.

[Embodiments of the invention]

FIG. 1 is a block diagram showing the configuration of a first embodiment of the present invention. In the figure, 1 is an xi tube as a radiation generator, and X-rays 2 generated from this X-ray tube 1 are collimated into a fan beam shape and are collimated into a specific cross section 3a of the object 3 to be inspected.
, and the intensity of the transmitted light is detected by an X-ray detector 4 having a plurality of X-ray detection elements arranged opposite to the X-ray tube 1. Here, the X-ray tube 1 and the X-ray detector 4 are operated based on a so-called third generation scanning method in which the X-ray tube 1 and the X-ray detector 4 are rotationally driven by a drive means (not shown). Reference numeral 5 denotes a data acquisition section, which obtains X-ray absorption data based on electrical signals corresponding to the transmitted intensity of X-rays 2 output from each X-ray detection element of the X-ray detector 4, and performs offset correction and reference correction. After the processing, the image is transferred to the image reconstruction calculation section 6. ” - The old image reconstruction calculation unit 6 corrects the transferred X-ray absorption data by performing calculations such as convolution to obtain projection data, and calculates the projection data by performing calculations such as convolution on the transferred X-ray absorption data. Image data at each pixel position on a two-dimensional plane is obtained by performing back projection from the radial direction. The image data obtained by the image reconstruction calculation unit 6 is stored in the image data storage unit 7,
It is displayed as a tomographic image 10 on a display 9 via a display interface 8 as necessary.

As shown in FIG. 2, the tomographic image 10 displayed on the display 9 consists of approximately 320×320 pixels, and each pixel indicates the X-ray absorption coefficient μ of the subject 3 corresponding to that pixel. There is. This X-ray absorption coefficient μ is 7, which is generally converted into a Hounsfield Namper (hereinafter abbreviated as CT value) whose absolute value is calibrated so that water is O1 and air is -1000.

That is, 6-CT value - [(μ-uw) / uw) x 100
0 - (1) (μW: X-ray absorption coefficient of water), and the height of this CT value is displayed on the display 9 as the height of brightness.

Let's return to Figure 1. Reference numeral 11 in FIG. 1 is an ROI designation input unit for designating a desired region, so-called region of interest (hereinafter abbreviated as R○I) 12, for which density is to be determined in the tomographic image 10 displayed on the display 9; and joysticks are used. Note that the shape of the RO 112 specified by the ROI specification input section 11 is as follows:
It can be any shape, such as a square or a circle. 13 is a CT value average calculation unit, which calculates the R specified in the ROI specification input unit 11 above.
Obtain the CT value for each pixel in O112, and calculate these C
There is a problem with calculating the average T value. 14 is the above R
This is a data input section for inputting necessary data such as the molecular formula 2 composition formula of the substance existing in the RO 112 specified by the OI specification input section 11 or the weight ratio of each molecule, and a keyboard or the like is used. Reference numeral 15 denotes a data table as a storage section, in which information necessary for density calculation, such as the atomic weight and mass absorption coefficient of each atom, is stored in advance. 16 is a calculation unit, which calculates the data table 1 based on the necessary data inputted by the data input unit 14.
Information regarding the mass absorption coefficient in the RO 112 is obtained from the atomic weight and mass absorption coefficient of each atom stored in From the average CT value as information regarding the calculated X-ray absorption coefficient, the above RO1
This is a calculation unit that calculates the density within 12, and this calculation unit 16
The calculation result in is displayed on the display section 17 of the display 9, as shown in FIG.

Here, the principle of determining the density in the removed tomographic plane of the subject 3 from the CT value will be explained. The CT value is expressed by the X-ray absorption coefficient μ of the object to be inspected 3, the X-ray absorption coefficient μW of water, etc., as shown in equation (1) above. On the other hand, the relationship between the X-ray absorption coefficient μ and the mass absorption coefficient μ′ is μ−ρ.
Since there is a relationship μ′ (ρ: density), the above (1)
The formula can be rewritten as (ρμ′−ρW·μ′w) CT value−x 1ooo (2) ρW·μ′W. However, μ'W represents the mass absorption coefficient of water, and ρW represents the density of water.

On the other hand, since the above ρw=1, by replacing it with μ'w/μ'-, the density ρ of the inspected object 3 is calculated from the above equation (2) as ρ-k ((CT(direct/1000) +1)
...obtained from (3). That is, by determining the ratio of the mass absorption coefficients of water and the object 3 to be inspected as 1 .mu.'w/.mu.', the density .rho. of the object 3 to be inspected can be determined from the CT value. The mass absorption coefficient μ' is determined by the type of atoms constituting the substance, their mass ratio, and the effective energy of the irradiated radiation (X-ray 2 in this example), and is determined by the state of the substance (gas, (liquid, solid) independent.

Next, the operation of this embodiment will be explained with reference to the flowcharts shown in FIGS. 4 and 5.

FIG. 4 shows the ROT specified by the RO,1 specification input section 11.
A case is shown in which the substance within 12 consists of a single molecule.

It is now assumed that the display 9 is displaying an eye shadow and a reconstructed tomographic image 10 by a CT scanner. In this state, the operator specifies the ROT 12 for which the density of the tomographic image 10 is to be measured using the ROI specification input section 11 (
Step (hereinafter abbreviated as ST) 1). At this time, the specified RO 112 has a different display form to be distinguished from other areas. Once the designation of the RO112 is completed, the substance constituting the Rol12 is input in the form of a molecular formula or a compositional formula using the data input section (ST2). Then 1. The average CT value within the ROT 12 is calculated by the CT value average calculation unit 13 (ST3). At the same time, the atomic weight and mass absorption coefficient for each atom stored in the data table 15 are called out based on the molecular formula or composition formula panned in the data input section 14, and the calculation section 16 calculates the following values. ROI12 according to equation (4)
The mass absorption coefficient μ' of the internal substance is calculated (Sr4).

However, in equation (71), n is the number of atoms constituting the input molecular formula or compositional formula, μ'1 is the mass absorption coefficient of the first atom, A1 is the atomic weight of the first atom, and al is the number of atoms constituting the input molecular formula or composition formula. It shows the number.

For example, the material constituting ROT 1 '2 is Si3N
4, when the data S+3N4 is input from the data input unit 14, the atomic weight -28 and mass absorption coefficient -0,442 of silicon 3i are called out from the data table 15, and the atomic weight -14 and mass of nitrogen N are called out. The absorption coefficient -0,195 is called. Then, based on each of the retrieved data, the arithmetic unit 16 performs the
The formula is calculated to determine the mass absorption coefficient μ' of the RO 112 made of 5iaN4. That is, μ' = (0,442X28X3 + 0.195X
14X4 ) /28X3 +14X4 = 0.343 However, the effective energy of X-ray 2 is assumed to be 50 keV.

On the other hand, the mass absorption coefficient μ'W of water is also calculated by the above equation (4), but this value may be set in advance.

Next, in the calculation unit 16, the ratio k between the mass absorption coefficient μ' of the substance in the RO 112 calculated by the above equation (4) and the mass absorption coefficient μ'W of water is calculated, and this ratio is calculated based on this ratio. , the density ρ is calculated from the average CT value calculated by the CT value average calculation unit 13 according to the equation (3) (S
r5). This calculation result is displayed on the display section 17 of the display 9 (Sr6).

FIG. 5 shows ROT1 designated by the ROI designation input section 11.
The case where the substance in 2 consists of multiple molecules is shown. In this case, the density can be calculated by calculating the average CT value within the RO 112 and calculating the density based on this average CT value, or by calculating the density of the substance within the RO 112 for each pixel. There is a means for calculating the density within the RO 112 after determining the density. In the former method, the operator
(2) When the designation of the RO 112 is completed in the designation input section 11, the quality and weight ratio of the substances in the RO 112 are inputted in the data input section 14 (Sr1).

Then, the average CT value is calculated in the CT value average calculation unit 13 (Sr8). At the same time, the calculation unit 16 calculates the mass yield coefficient μ' of the substance in the RO 112 based on the following equation (5).

However, in equation (5), n is the number of molecules that contain the substance in RO112, and μ'1 is the mass absorption coefficient 9 of the i-th molecule.
m1 indicates the molecular weight of the i-th molecule, and C1 indicates the weight composition ratio of the first molecule.

That is, first, the mass absorption coefficient of all the substance molecules of the substance in RO 12 is calculated (Sr9), and then the mass absorption coefficient of the substance in RO 112 is calculated from the mass absorption coefficient values of all the molecules (Sr9). ST10). Then, the density is calculated from this mass absorption coefficient and the average CT value (S
T11), displayed on the display section 17 of the display 9 (
ST12).

On the other hand, when calculating the density in units of one pixel, first display one pixel for which density calculation is to be performed on the display 9 (ST1
3) The molecular formula or the molecular formula and weight ratio are input through the data input section 14, taking into account whether each molecule within one displayed pixel is a mixture or a pure substance (ST14). When the data input described above is completed for all pixels in the RO 112, the mass absorption coefficient is calculated for each pixel in the calculation section 16 (ST15). Furthermore, the density for each pixel is calculated from the calculated mass absorption coefficient and the CT value obtained for each pixel (ST16). And R
When the density calculation for the 1-quality pixel in 0112 is completed, the average value of the density in RO112 is calculated (
ST17), the calculated value is displayed on the display section 17 of the display 9.
is displayed (ST12).

Thus, according to this embodiment, the molecular formula of the substance constituting the vfI layer image 10 photographed by the 0-piece scanner.

By inputting the compositional formula or weight ratio, the density within the photographed tomographic plane of the object to be inspected 3 can be calculated non-contactly and non-destructively. Therefore, especially when the CT scanner is used for industrial purposes, it is effective for compositional analysis of the inspected object 3, product management, etc.

FIG. 6 shows a flowchart as a second embodiment of the present invention when the ROI designated by the ROI designation input section 11 is one pixel. As described above, the data input by the data input unit differs depending on whether the substance within one pixel is a mixture or a pure substance. In the case of a mixture, input the molecular formula of the substance contained in one pixel and its weight ratio (ST18)
. Then, the mass absorption coefficient is calculated for each molecule in the calculation unit 16 (ST19). Once the mass absorption coefficients have been calculated for all molecules, the total mass absorption coefficient of the mixture is calculated (ST20).

Next, since the mixture ratio of molecules mixed in one pixel is reflected in the CT value, density calculation is performed from the total mass absorption coefficient and the CT value of the pixel designated as ROI (ST21).

The calculation result is then displayed on the display section 11 of the display 9 (ST22).

On the other hand, in the case of a pure product, enter the molecular formula of the pure product (8
Ding 23). Then, the mass absorption coefficient of the pure substance is calculated (ST24), and the density is calculated using J: between this mass absorption coefficient and the 0-density value of the pixel specified by ROT (ST21).
>, the calculation result is displayed on the display section 17 of the display 9 (ST22).

Thus, according to this embodiment, the same effects as those of the first embodiment can be achieved.

Note that the present invention is not limited to the above embodiments.

For example, in each of the above embodiments, the case where the density is calculated is shown, but for example, if the density of one pixel is calculated, the volume of this one pixel is well known, so by multiplying this density by the volume, It is also possible to determine the weight of a substance in a pixel.Also, in the above embodiment, the case where the density is determined from the tomographic image 10 obtained by a third generation CT scanner is applicable. .2nd and 4th generation C
The density may be determined from the tomographic image 10 obtained by a T-scanner. It goes without saying that various other modifications can be made without departing from the gist of the present invention.

〔Effect of the invention〕

As described in detail above, according to the present invention, image reconstruction processing is performed on radiation absorption data obtained by irradiating a specific cross section of the object to be inspected, image data regarding the specific cross section is obtained, and Information regarding a substance in a specific cross section of the body is inputted by an input means, information regarding density calculation is obtained from a storage section in accordance with the information inputted by this input means, and information regarding density measurement obtained from this storage section and the image data are obtained. Since the density within a specific cross section of the object to be inspected is calculated from In particular, it is possible to provide an image processing device that is excellent in compositional analysis of industrial products and their product materials, management of industrial products and materials, and the like.

[Brief explanation of the drawing]

1 to 5 are diagrams showing a first embodiment of the present invention, in which FIG. 1 is a block diagram without showing the configuration, and FIG. 2 is a diagram without showing a tomographic image displayed on a display. , FIG. 3 is a diagram showing the display section of the display, FIGS. 4 and 5 are flowcharts for explaining the operation, and FIG. 6 is a flowchart for explaining the operation of the second embodiment of the present invention. 1... X-ray tube, 2... X-ray, 3... Test object, 4
. . . X-ray detector, 5 . . . Data collection unit, 6 .
- Display interface, 9... Display, 10... Tomographic image, 11... ROI designation input section, 1
2... ROI (region of interest), 13... CT value average calculation unit, 14... data input unit, 15... data table, 16... calculation unit, 17... display unit.

Claims (6)

[Claims] (1) A tomographic imaging means that performs image reconstruction processing on radiation absorption data obtained by irradiating a specific cross section of the object to be inspected to obtain image data regarding the specific cross section, and a substance in the specific cross section of the object to be inspected. an input means for inputting information regarding the density calculation, a storage section for storing predetermined information in advance so that information regarding the density calculation can be obtained according to the information inputted by the input means, and information regarding the density measurement obtained from the storage section. An image processing apparatus comprising: a density calculating means for calculating a density within a specific cross section of the object to be inspected from image data obtained by the tomographic imaging means. (2) The image processing apparatus according to claim (1), wherein the image data is a CT value of one pixel. (3) In the case where a plurality of substances are mixed in one pixel, the image data is a CT value corresponding to the mixing ratio. ). (4) The image processing apparatus according to claim (1), wherein the input means includes a setting means for setting a desired area of image data. (5) The density calculation means calculates the average value of CT values in a desired region, and calculates the density from this average CT value and information regarding density calculation. ) and (4). (6) The density calculation means calculates the density of each pixel in the desired area, and calculates the average value of the calculation results. ).