JPH0546074A - Biophantom - Google Patents

Abstract

PURPOSE:To provide the biophantom which electrically faithfully simulate animals and plants. CONSTITUTION:This biophantom is constituted by sealing the liquid uniformly mixed with an aq. electrolyte soln. or pure water and a polar org. compd. into a container having >=0.9 electromagnetic wave transmittance. An example of the polar org. compd. includes monohydric or polyhydric alcohol. The exact simulation for estimation of the frequency absorbing power of a living body, the influence on radio equipment, the influence of electromagnetic waves on a heart pace maker and the estimation of the sectional area of a radar is possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a living body phantom for electrically simulating a living body in a high frequency band.

[0002]

2. Description of the Related Art As a living body phantom for electrically simulating a living body in a high frequency band, it is conventionally known to use an aqueous sodium chloride solution enclosed in an appropriate container. For example, IEC Publication (IEC
Publication) 489-6 [Methods of measurement for Radio Radio Equipment Used in the Mobile Service, Part 6: Selective-Calling and Data Equipment (Methods of measurement f)
or radio equipment used i
n the mobile services, Par
t6: Selective-calling and
Data equipment (1987)] Appendix H (Appendix H) describes a method of simulating a human body by filling a cylindrical container with an aqueous sodium chloride solution having a concentration of 1.49 g / l (0.025 mol / l). Have been described.

[0003]

By the way, in such a conventionally known biological phantom in which a sodium chloride aqueous solution is enclosed, the complex relative permittivity ε at a certain frequency is uniquely determined by the sodium chloride concentration, and ε
It was impossible to arbitrarily change the real part ε ′ and the imaginary part ε ″ of the above. For example, at the frequency of 1 GHz and the temperature of 25 ° C., the above-mentioned concentration was 1.49 g / l (0.025 mol / l).
The complex relative permittivity of the sodium chloride aqueous solution is about 78-j8, which is about 50 of the complex relative permittivity of the muscles and organs of the living body.
It is very different from -j25. Furthermore, the complex relative permittivity of animals and plants differs depending on the type and tissue, and in order to faithfully simulate their electrical characteristics, match both the real part and the imaginary part of the complex relative permittivity to the one you want to simulate. Although it is necessary, a living body phantom in which a liquid capable of freely changing the real part and the imaginary part is enclosed has not been known. An object of the present invention is to provide a living body phantom that electrically mimics an animal or a plant.

[0004]

Means for Solving the Problems The present invention will be described in brief. The present invention relates to a living body phantom, in which a liquid obtained by uniformly mixing an aqueous electrolyte solution or pure water and a polar organic compound has an electromagnetic wave transmittance. It is characterized by being enclosed in a container of 0.9 or more.

The present invention is intended to solve the above-mentioned problems, and in order to realize a wide range of complex relative permittivity, a solution in which an electrolyte is dissolved in water and a polar organic compound are placed inside a living body phantom. The composition of the liquid to be enclosed.

When an electrolyte is added to water, the electrolyte is separated into positive hydrated ions and negative hydrated ions in water, and the electrolyte dissolves in water. On the other hand, the polar organic compound is a general term for organic compounds having polarity, and includes OH group, NO ₂ group, NH ₂ group,
It has polar groups such as COOH groups, and when mixed with water, hydrogen atoms in water molecules and these polar groups form hydrogen bonds, and mixed with water or an aqueous electrolyte solution in a wide range of volume ratio. In particular, a polar organic compound that is liquid at room temperature is generally mixed with pure water or an aqueous electrolyte solution at an arbitrary volume ratio.

Therefore, the liquid of the present invention can be uniformly mixed, and by enclosing the liquid in a container having a large electromagnetic wave transmittance of, for example, 0.9 or more, a living body that faithfully simulates the electrical characteristics of the living body is obtained. Phantom can be realized. As the shape of the container, it is considered that the living body is approximated by a sphere, a spheroid, a cylinder, or a combination thereof, or a body that more closely simulates the shape of the living body.

[0008]

The real part ε'of the complex relative permittivity ε of water is larger than many substances, and is about 78 from DC to the UHF band, but the imaginary part ε ″ is considerably smaller than the real part ε '. However, when the electrolyte is dissolved in water, ε ″ increases due to ionic conduction. At this time, the change of ε ′ remains slight.
On the other hand, ε'of a polar organic compound is larger than that of a nonpolar organic compound having no polar group, but is generally a fraction or less (for example, 10 to 30) smaller than that of water. ε ″ is about the same as or slightly smaller than ε ′ and about the same as water. Therefore, by mixing a polar organic compound with water, the real part ε ′ of the complex relative permittivity is, for example, 10 to 7.
It can be adjusted in the range of 8. At this time, the change of ε ″ remains small. Further, if a polar organic compound and an electrolyte aqueous solution are mixed instead of pure water, ε ′ can be adjusted within the above range, and at the same time, ε ″ can be adjusted to the electrolyte concentration. You can make a big change by changing. That is, in a liquid dielectric material composed of pure water or an aqueous electrolyte solution and a polar organic compound, both the real part and the imaginary part of the complex relative permittivity can be realized over a wide range, and the real part of the complex relative permittivity can be realized. Both the imaginary part and the imaginary part can faithfully electrically simulate a large living body. On the other hand, a container having a large electromagnetic wave transmittance is almost transparent to electromagnetic waves.

As the polar organic compound in the present invention, those which are not corrosive or explosive are desirable, and monohydric alcohols or polyhydric alcohols are preferred to those which are not neutral such as acetic acid and those which are explosive such as nitroglycerin. (Diethylene glycol, glycerin, etc. other than ethylene glycol), polyacrylic acid, polyacrylamide,
Polyvinylamine and the like are suitable, and any one of them can realize the complex relative permittivity as shown in FIGS. 1 to 3 or 5.

[0010]

EXAMPLES The present invention will now be described in detail according to examples, but the present invention is not limited to these examples.

Example 1 Using sodium chloride as the electrolyte and ethylene glycol which is one of the dihydric alcohols as the polar organic compound, the sodium chloride concentrations shown in Tables 1 and 2 and the volume ratio of the aqueous sodium chloride solution to ethylene glycol were used. A liquid sample consisting of the mixed liquid of the combination was prepared, and the complex relative dielectric constant was measured at a temperature of 25 ° C.

[0012]

[Table 1]

[0013]

[Table 2]

When preparing a mixed solution, first, sodium chloride is dissolved in pure water, and then an aqueous solution of sodium chloride having a desired volume ratio is mixed with ethylene glycol. At this time, if a volume x sodium chloride aqueous solution (or generally an electrolyte aqueous solution) and a volume y ethylene glycol (or generally a polar organic compound) are mixed, the volume of the mixed solution becomes (x +
Since it is smaller than y), if ethylene glycol is added to a container containing a sodium chloride aqueous solution of volume x until the total volume becomes (x + y), it does not mean that the volume ratio is x: y. Need attention.

The complex relative permittivity was measured by an open-ended coaxial probe method suitable for measuring liquids. The measurement method was verified by using an aqueous solution of sodium chloride, which has a well-known complex relative permittivity, and the measurement accuracy was obtained to be several percent or less in both the real part and the imaginary part of the complex relative permittivity.

The results of measuring the complex relative permittivity of the samples shown in Tables 1 and 2 at frequencies of 0.5, 1 and 1.5 GHz are shown in FIGS. The complex relative permittivity changes continuously when the sodium chloride concentration or volume ratio is changed,
The curve connecting the points representing the sample represents the complex relative permittivity of the mixed liquid having the composition between the samples. From these figures, it can be seen that a wider range of complex relative permittivity can be realized as compared with the conventional sodium chloride aqueous solution by changing the volume ratio of the sodium chloride aqueous solution and ethylene glycol and the concentration of the sodium chloride aqueous solution. In addition, sample numbers 1 to 6 on the alternate long and short dash line in FIGS. 1 to 3 are aqueous solutions of sodium chloride or pure water, and sample number 25 shown by ◯ is a simple substance of ethylene glycol, which are outside the scope of the present invention. Is. Further, in FIG. 4, sample numbers 3 (0.6 mol / l sodium chloride aqueous solution) and 15 (0.6 mol / l sodium chloride aqueous solution and ethylene glycol in volume ratio 1:
(Mixed in 1) and 25 (ethylene glycol) are shown. The mixed liquid 15 exhibits an intermediate frequency dispersion characteristic different from both the sodium chloride aqueous solution 3 and the ethylene glycol 25. In FIG. 4, the horizontal axis represents frequency (GHz) and the vertical axis represents ε ′ and ε ″.

Example 2 Using sodium chloride as the electrolyte and ethyl alcohol which is one of the monohydric alcohols as the polar organic compound, the sodium chloride concentrations shown in Tables 3 and 4 and the volume ratio of the sodium chloride aqueous solution to the ethyl alcohol were used. FIG. 5 shows the result of measuring the complex relative permittivity at a temperature of 25 ° C. by preparing a liquid sample composed of the mixed liquid of the combination of. The measurement frequencies are 0.5, 1 and 1.5 GHz. Even in this case, it is understood that a wide range of complex relative permittivity can be realized by changing the volume ratio of the sodium chloride aqueous solution and the ethyl alcohol and the concentration of the sodium chloride aqueous solution. Sample numbers 1 to 6 on the alternate long and short dash line in FIG. 5 are sodium chloride aqueous solutions or pure water, and sample number 44 indicated by O is ethyl alcohol alone, which are outside the scope of the present invention.

[0018]

[Table 3]

[0019]

[Table 4]

Comparing FIGS. 1 to 3 with FIG. 5, the difference between the dihydric alcohol (ethylene glycol) and the monohydric alcohol (ethyl alcohol) appears. That is, in the lower left area of each graph in the region where the volume ratio of the sodium chloride aqueous solution near ethylene glycol 25 or ethyl alcohol 44 is small, the group of curves is closer to ethylene glycol,
Even if the sodium chloride concentration is increased, ε ″ does not become as large as in the case of ethyl alcohol. This can be explained as follows: A dihydric alcohol has two OH groups per molecule and one monohydric alcohol has one. The OH group forms a hydrogen bond with a hydrogen atom of a water molecule, so alcohols bind water molecules, and polyhydric alcohols bind more water molecules than monohydric alcohols. The various electrolytes dissolve in water and become Na (H ₂ O) x ⁺ , Cl (H
₂ O) y ^-. Make a hydrated ions, such as, for these hydrated ions move in response to an applied electric field, epsilon "is increased by the ion conduction However, as the such as alcohol are present simultaneously the water Since the molecules are constrained, the number of water molecules that can contribute to making hydrated ions and increasing ε ″ is reduced. That is, even if the electrolyte concentration increases, ε ″
The effect is that the is hard to grow. Moreover, the larger the alcohol valence (generally, the number of polar groups per molecule), the more remarkable this effect is. Therefore, ε'is 10
When it is desired to increase ε ″ in the range of about 30 to 30, it is appropriate to use a polar organic compound having a small number of polar groups per molecule.

[0021]

The biological phantom of the present invention is capable of accurately simulating the electrical characteristics of a living body by combining a liquid capable of easily realizing a complex relative permittivity over a wide range and a container having a large electromagnetic wave transmittance. It will be possible. Therefore, when estimating the high-frequency absorbed power when a living body is exposed to an electromagnetic field, when estimating the antenna characteristics and receiving sensitivity when a wireless device is placed near the human body, the electromagnetic immunity of an implantable cardiac pacemaker is estimated. In such a case, or when estimating a radar cross-section when an electromagnetic wave hits a living body, accurate estimation becomes possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a complex relative dielectric constant at a frequency of 0.5 GHz of a mixed liquid of ethylene glycol and an aqueous sodium chloride solution as an example of a liquid to be sealed in a living body phantom according to the present invention.

FIG. 2 is a diagram showing a complex relative dielectric constant at a frequency of 1 GHz in the mixed liquid of FIG.

FIG. 3 is a diagram showing a complex relative dielectric constant at a frequency of 1.5 GHz in the mixed liquid of FIG.

FIG. 4 is an aqueous sodium chloride solution having a concentration of 0.6 mol / l,
FIG. 3 is a diagram showing a mixture of an aqueous sodium chloride solution having a concentration of 0.6 mol / l and ethylene glycol at a volume ratio of 1: 1 and a frequency characteristic of a complex relative dielectric constant of ethylene glycol.

FIG. 5 is a diagram showing complex relative dielectric constants at a frequency of 0.5, 1 and 1.5 GHz of a mixed solution of ethyl alcohol and an aqueous sodium chloride solution as another example of the liquid sealed in the living body phantom according to the present invention. ..

Claims (2)

[Claims] 1. A living body phantom, characterized in that a liquid in which an electrolyte aqueous solution or pure water is uniformly mixed with a polar organic compound is sealed in a container having an electromagnetic wave transmittance of 0.9 or more. 2. The living body phantom according to claim 1, wherein the polar organic compound is a monohydric or polyhydric alcohol.