JPH09243576A - Method and apparatus for tomography by two-dimensional time domain reflection method - Google Patents

Abstract

(57) Abstract: A tomographic imaging method and apparatus using a two-dimensional time domain reflection method capable of accurately measuring a required physical quantity of an object to be measured two-dimensionally. In a tomography method using a two-dimensional time domain reflection method, a sensor having a plurality of electrodes arranged in a line
With the object to be measured 1, the surface of the object to be measured 1 is scanned perpendicularly to the arrangement direction of the electrodes, the information based on this scanning is processed, and the necessary physical quantity is distributed based on this information. Can be displayed as

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION TDR (Time Domain)
in Reflectometry-CT (Com
The use of computer tomography [time domain reflectometry-computed tomography]
It is considered to cover various areas such as cosmetics, food, machinery, construction and civil engineering. In particular, it has a great potential for application to medical treatment, and is used to diagnose human skin burns and skin cancers, diagnose diseases such as cancers within the reach of endoscopes, and sensors (0.
1 to 5 mmφ) It is possible to diagnose skin that can be touched by the tip, cerebral infarction, emphysema, pulmonary fibrosis, cirrhosis, etc., and diagnosed excised organs or diseased parts.

In addition, free water and bound water play an important role in quality measurement of freshness of foods, evaluation of processing technology, electronic materials, mechanical materials such as ceramics, construction materials such as concrete and asphalt, and soil quality. It can be used for evaluation of rheological properties.

[0003]

2. Description of the Related Art Conventionally, the following techniques are available as techniques close to the above-mentioned TDR-CT. (1) NMR-CT (Nuclear Magneti)
c Resonance Computer Tomo
[Graphic] [Nuclear Magnetic Resonance Tomography] According to this NMR-CT, a cross-sectional image of the measured object can be obtained due to the difference in the existence state of water molecules in the tissue. The difference in the existence state is, specifically, the magnetic relaxation time (T1) of the water molecule.
However, it is understood that this is due to the speed of rotational movement of water molecules contained in the tissue.

(2) X-ray-CT According to this X-ray-CT, a cross-sectional image of the object to be measured can be obtained by utilizing the difference in the X-ray absorption coefficient of each tissue in the living body.

[0005]

However, according to the above-mentioned conventional (1) NMR-CT, the TD in NMR is
Since only the averaged information of the two types of water observed in R can be obtained, bound water and free water cannot be observed separately. In addition, since T1 does not include quantitative information on water, the water content of the measured object is quantified (Quantitative).
ation) is also impossible.

Further, according to the above-mentioned conventional (2) X-ray-CT, since the X-ray absorption coefficient of the substance in the tissue of the object to be measured is measured, it is impossible to quantify the water content. . Further, according to the above-mentioned NMR-CT, there is no destruction or exposure of the object to be measured, but in this X-ray-CT, radiation is used, so the object to be measured is exposed. SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned problems and provide a tomographic imaging method by a two-dimensional time domain reflection method and an apparatus therefor capable of accurately measuring a required physical quantity of an object to be measured two-dimensionally. To do.

[0007]

According to the present invention, in order to achieve the above object, [1] in a tomography method by a two-dimensional time domain reflection method, a sensor in which a plurality of electrodes are arranged is used as an object to be measured. The contact is made, the surface of the object to be measured is scanned perpendicularly to the arrangement direction of the electrodes, information based on this scanning is processed, and a two-dimensional image is displayed based on this information.

[2] In the tomographic method by the two-dimensional time domain reflection method described in [1] above, the object to be measured is a biological material, and free water and bound water are separated and observed by a dielectric spectrum, The amounts of these two types of water are individually quantified. [3] In the tomographic imaging method by the two-dimensional time domain reflection method described in [1] above, the processing of the information is performed by calculating the dielectric constant of the biological material.

[4] In the tomographic imaging method by the two-dimensional time domain reflection method described in [3] above, a necessary physical quantity is calculated based on the dielectric constant. [5] In the tomographic imaging method by the two-dimensional time domain reflection method described in [4] above, the required physical quantity is the amount of water. [6] In the tomographic method by the two-dimensional time domain reflection method described in [4] above, the necessary physical quantity is a relaxation time of water motion.

[7] In a tomography apparatus using the two-dimensional time domain reflection method, a sensor having a plurality of electrodes arranged in contact with an object to be measured and the surface of the object to be measured are perpendicular to the arrangement direction of the electrodes. There is provided a scanning means for scanning, an information processing means for processing information from the scanning means, and a display device for displaying a two-dimensional image based on the processed information.

[8] In the tomography apparatus by the two-dimensional time domain reflection method described in [7], the plurality of electrodes are 2
It is arranged in a three-dimensional manner so that the object to be measured is scanned. As described above, the TDR method (time-domain reflection method) can be used for a wide frequency (100 kHz to 10 GH) in a short time only by contacting the cross-sectional end of the coaxial cable with a substance.
The dielectric spectrum of z) can be measured, and it is currently used mainly for physical property research mainly on biological materials. A large amount of water is contained in biological materials, but in the dielectric spectrum, water that is in a normal state, "free water", and "bound water," which is bound by biopolymers and is relatively hard to move, are included in this spectrum. Since they can be observed separately, the “amount” of these two types of water can be quantified separately.

This makes it possible to obtain detailed information on water near the surface of the substance. The greatest advantage of using microwaves in TDR-CT is that water can be separated into two types and quantified in this way, and current electrodes have a diameter of 0.1 m.
Although the dielectric constant of a part of about m to 5 mm is measured,
When a sensor in which several of these electrodes are arranged on a straight line is brought into contact with the object to be measured and is vertically scanned, information on the two-dimensional plane of the dielectric constant can be obtained.

Image processing of these pieces of information is performed, and necessary physical quantities are displayed as a distribution image. Two-dimensional TDR-CT
Is effective for measuring the amount of water in a substance and for evaluating the water structure, and provides knowledge of the water content of the substance, the ratio of bound water to free water, and the dynamic structure of the molecule. The two-dimensional distribution of such information can be observed through the image display.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a two-dimensional TDR-CT showing an embodiment of the present invention. In this figure, A is a microwave transmission / measuring system, B is a microcomputer, 1 is an object to be measured, 2 is a pulse generator, 3 is a sensor that contacts the object to be measured, 4 is a sampling head, 5 is A / D conversion. Reference numeral 6 denotes a dielectric constant calculation unit that performs waveform processing and Fourier transform. Reference numeral 7 denotes a physical quantity calculation unit that calculates a necessary physical quantity, for example, calculates a water content and a relaxation time of water movement. Reference numeral 8 is a storage unit capable of storing such information, and 9 is a display device (two-dimensional image display device).

Here, the pulse generator 2, the sampling head 4, and the A / D converter 5 are incorporated in one device as a microwave transmission / measurement system A. Further, the calculation of the dielectric constant and the calculation of the required physical quantity are performed by the microcomputer B.
Do with. Although FIG. 1 shows the microcomputer B and the display device 9 separately, the microcomputer B can also display an image.

First, the pulse generator 2 raises a step pulse. The pulse passes through the coaxial cable and is incident on the sensor 3 portion. The pulse is reflected on the contact surface between the sensor 3 and the DUT 1, and the reflected wave is captured by the sampling head 4. The reflected wave taken into the sampling head 4 is A / D converted by the A / D converter 5. The complex permittivity is obtained by sending this to the microcomputer B and subjecting the permittivity calculator 6 to waveform processing and Fourier transform.

Further, based on the calculated complex permittivity, the physical quantity calculator 7 calculates necessary physical quantities such as the water content and the relaxation time of the motion of water, and the information is stored as necessary. It can be stored in the unit 8. Further, such information can be displayed on the display device 9 as a two-dimensional image. The two-dimensional TDR-CT has a sensor 3 as shown in FIG. The sensor 3 comprises a plurality of electrodes 10 arranged in a line. The specific structure of the electrode 10 is shown in FIG.
As shown in FIG. 1, a center inner conductor 11, an insulator 12 surrounding the center inner conductor 11, and an outer conductor 13 formed concentrically outside the insulator 12
And 3A is a horizontal sectional view of the electrode 10, and FIG. 3B is a vertical sectional view of the electrode 10.

The sensor 3 described above is scanned with respect to the DUT 1 as shown in FIG. And XY of FIG.
The physical quantity calculator 7 calculates necessary physical quantities such as the water content at each position on the plane and the relaxation time of water molecule motion. The physical quantity thus obtained can be stored in the storage unit 8 as necessary and can be displayed as a two-dimensional image on the display device 9.

Thus, the two-dimensional TDR-CT of the present invention
According to this, when the sensor 3 composed of a plurality of electrodes 10 arranged on a straight line is brought into contact with the object to be measured and vertically scanned, information on the two-dimensional plane of the dielectric constant can be obtained. By processing these pieces of information, necessary physical quantities can be displayed as a distribution image.

[0020]

EXAMPLES The evaluation of the distribution of water content in the cross section of vegetables using the TDR method of the present invention will be described. By performing dielectric measurement using the TDR method, the distribution of water content in the vegetable cross section is evaluated.

As a sample, one cucumber, carrot, taro, turnip, and shiitake mushroom was tested. The results will be described below in order. (Experimental apparatus) Using the TDR system of the present invention, 100
Dielectric measurement was performed in the frequency range of MHz to 10 GHz.
The cable is made by Junkosha Co., Ltd. (DGM224) with a length of 50 cm.
The electrode is a contact type (φ 6.0 mm, γd = 0.
355 mm) was used. Here, γd represents the electrical length of the electrode. The electrode has an electric circuit similar in structure and function to a capacitor, and corresponds to the electric capacity of the capacitor. Therefore, the larger γd is, the higher the sensitivity of the electrode is, but the characteristics on the high frequency side of the signal are deteriorated.

(Experimental Method) Each of several measurement points was cut out with a blade, and a contact type electrode was applied to the measurement points for measurement. Waveform integration in the time domain was 32 times per measurement point. One point measurement is about 1 minute. Water was used for cucumber, carrot, taro and turnip, and acetone was used for shiitake as standard samples. The measurement points of each sample are shown in FIGS. 5, 6, 7, 8, and 9, respectively.

(Results) Dielectric parameters were determined from the complex permittivity obtained by the measurement. 10 in the measurement frequency range
Relaxation is observed around 0 MHz and around 20 GHz. Relaxation on the high frequency side is due to free water. From the relaxation strength of this relaxation process, the ratio of free water per unit volume can be estimated using the equation (1).

C = (Δε / Δεw) × 100 (1) where Δε is the relaxation strength of free water obtained by measurement, Δε
w is the relaxation strength of pure water. Also, Δεw is 73.
It was set to 0. (1) of each measurement point in each sample
The water content obtained from the formula is sequentially shown below for cucumber, carrot, taro, turnip, and shiitake mushroom.

From the result, it is possible to know the tendency of the distribution of the water content in the cross section of the sample. FIG. 5 is a diagram showing the shape and water content of cucumber as a sample showing an example of the present invention. FIG. 5 (a) shows the measurement site and water content of cucumber, and FIG. 5 (b) shows the water content of that cucumber. The shape is shown.

As is apparent from this figure, in the case of the cucumber 20, the stem side 21 has a higher water content than the flower side 22. Seed 23
The pulp 24 has a higher water content than the pulp. FIG.
FIG. 6 is a diagram showing the shape and water content of carrot as a sample showing an example of the present invention. FIG. 6 (a) shows the measurement site and water content of carrot, and FIG. 6 (b) shows the shape of the carrot. Shows the color.

As is clear from this figure, in the case of carrot 30, the core 31 has a large amount of water, and the amount of water decreases as it approaches the tip 32 of the root and the epidermis 33. In addition, 34 is a yellow part and 35 is a red part. FIG. 7 is a diagram showing the shape and water content of taro as a sample showing an example of the present invention, and FIG. 7 (a) shows the measurement site and water content of taro,
FIG.7 (b) has shown the shape of the taro.

As is clear from this figure, in the case of the taro 40, the central portion 41 has a small amount of water and the cut end 4 on the stalk side.
2 and the root tip 43 have a large amount of water. FIG. 8 is a diagram showing the water content of a turnip as a sample showing an example of the present invention. As is clear from this figure, in the case of the turnip 50, the central portion 51 has a large amount of water. FIG. 9 is a diagram showing the shape and water content of a shiitake mushroom as a sample showing an example of the present invention.
FIG. 9A shows the measurement site and water content of the shiitake mushroom, and FIG. 9B shows the shape of the shiitake mushroom.

As is apparent from this figure, in the case of the shiitake mushroom 60, the cut 61 is dry, and the back (fold) of the umbrella 6
The water content is high at 2,63. For reference, Table 1 shows the water content A per unit volume averaged for each sample. In addition, B of this Table 1 has shown the water content (g) contained per 100g described in the food ingredient table (Hitotsubashi Publishing, 1991).

[0030]

[Table 1]

As described above, the distribution of the water content in the vegetable cross section could be evaluated by the dielectric measurement using the TDR method, but it is necessary to devise the adjustment of the pressure when the electrode is brought into contact with the sample. . This is because too much pressure is applied to the electrodes and the tissue at the contact site is destroyed, or the electrodes do not come into close contact with the sample. Also, for sponge-like samples such as shiitake mushrooms,
This is because the density may change depending on how the pressure is applied.

Moreover, the measurement accuracy can be improved by increasing the number of times of integration. Further, by making the electrode thin, the number of measurement points can be increased and a finer distribution amount of water can be evaluated. As described above, it is possible to measure a complex dielectric spectrum in a wide frequency range in a short time, and it is currently used for physical property research to investigate the dynamic structure of molecules contained in biopolymers, synthetic polymers and biological tissues. There is.
In the TDR method, a step pulse is emitted from the apparatus main body and reflected at the electrode tip through the coaxial cable. However, when an electrode having a cross section of the coaxial cable is used, an electric field leakage of about 1 mm occurs from the electrode surface. The complex permittivity can be measured only by bringing a substance into contact with the tip of such an electrode.

With the current electrodes, it is possible to measure the permittivity of a site having a diameter of about 0.1 to 5 mm, but a sensor consisting of several electrodes arranged in a straight line is brought into contact with the object to be measured to make it vertically. By scanning, information on the two-dimensional plane of the dielectric constant is obtained. Image processing of these pieces of information can be performed, and a required physical quantity can be displayed as a distribution image. It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made based on the gist of the present invention, and these are not excluded from the scope of the present invention.

[0034]

As described above in detail, according to the present invention, information on the two-dimensional plane of the dielectric constant of the sample can be obtained. Image processing of these pieces of information can be performed, and a required physical quantity can be displayed as a distribution image. Therefore, the present invention is effective for measuring the amount of water in a substance and evaluating the water structure.

As described above, in TDR-CT, an image of the water content distribution on the material surface can be obtained. A lot of water is contained in biological materials, but the dielectric spectrum shows that water is "free water" in a normal state, and "bound water" that is relatively hard to be bound by biopolymers. Since it is possible to separately observe, the “amount” of these two types of water can be individually quantified.

This makes it possible to obtain detailed information on water near the surface of the substance. The greatest advantage of using microwaves in TDR-CT is that water can be separated into two types and quantified in this way, which is not possible with NMR-CT or X-ray-CT. Moreover, since only a minute voltage is applied to the object to be measured, there is no fear of destruction or exposure to a living body. It is considered that such TDR-CT is used in a wide range of fields such as medical care, foods, and industrial materials. In particular, it has great potential for medical applications, and can diagnose human skin burns and skin cancer, diagnose diseases such as cancer within the reach of an endoscope, and diagnose excised organs and diseased parts. is there. Cost is 1/50 to 1/100 of NMR-CT and X-ray-CT
It can be manufactured by.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a two-dimensional TDR-CT showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of a two-dimensional TDR-CT sensor showing an embodiment of the present invention.

FIG. 3 is a configuration diagram of electrodes of a two-dimensional TDR-CT showing an example of the present invention.

FIG. 4 is an explanatory diagram of scanning by a two-dimensional TDR-CT sensor according to an embodiment of the present invention.

FIG. 5 is a diagram showing the shape and water content of cucumber as a sample showing an example of the present invention.

FIG. 6 is a diagram showing the shape and water content of carrot as a sample showing an example of the present invention.

FIG. 7 is a diagram showing the shape and water content of taro as a sample showing an example of the present invention.

FIG. 8 is a diagram showing a water content of turnip as a sample showing an example of the present invention.

FIG. 9 is a diagram showing the shape and water content of a shiitake mushroom as a sample showing an example of the present invention.

[Explanation of symbols]

 A microwave transmission / measurement system B microcomputer 1 object to be measured (sample) 2 pulse generator 3 sensor 4 sampling head 5 A / D converter 6 dielectric constant calculator 7 physical quantity calculator 8 storage 9 display device (two-dimensional image) Display device) 10 electrode 11 center inner conductor 12 insulator 13 outer conductor 20 cucumber 30 ginseng 40 taro 50 turnip 60 shiitake

Claims (8)

[Claims] 1. In a tomographic imaging method using a two-dimensional time domain reflection method, (a) a sensor in which a plurality of electrodes are arranged is brought into contact with an object to be measured, and (b) the surface of the object to be measured is arranged in an electrode arrangement direction. Vertical scanning is performed, (c) information based on the scanning is processed, and (d) a two-dimensional image is displayed based on the information, and a two-dimensional time domain reflection method tomography method. 2. The tomography method by the two-dimensional time domain reflection method according to claim 1, wherein the object to be measured is a biological substance, and free water and bound water are separated and observed by a dielectric spectrum, A tomography method using a two-dimensional time domain reflection method, characterized in that the amount of each type of water is quantified individually. 3. The tomography method according to the two-dimensional time domain reflection method according to claim 1, wherein the processing of the information is performed by calculating a dielectric constant of the biological material. How to shoot. 4. The tomography method by the two-dimensional time domain reflection method according to claim 3, wherein a necessary physical quantity is calculated based on the dielectric constant. . 5. The tomography method according to the two-dimensional time domain reflection method according to claim 4, wherein the required physical quantity is the amount of water. 6. The tomography method according to the two-dimensional time domain reflection method according to claim 4, wherein the required physical quantity is a relaxation time of motion of water. . 7. A tomography apparatus using the two-dimensional time domain reflection method, wherein (a) a sensor having a plurality of electrodes arranged in contact with the object to be measured, and (b) an array of electrodes on the surface of the object to be measured. Scanning means for scanning perpendicular to the direction,
Two-dimensional time domain reflection, comprising (c) information processing means for processing information from the scanning means, and (d) a display device for displaying a two-dimensional image based on the processed information. Tomography device by method. 8. The tomographic apparatus by the two-dimensional time domain reflection method according to claim 7, wherein the plurality of electrodes are arranged one-dimensionally and scan the object to be measured. Tomographic equipment by reflection method.