JPS6247535B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microwave detection device for detecting microwaves inside a body cavity.

Normally, an endoscope is used to visually observe the mucosal surface within a living body cavity, and it is impossible to discover, for example, a lesion unless it appears visibly.
On the other hand, it has recently been known that lesions such as cancer and tumors in living tissues are about 1° C. hotter than other normal tissues. Therefore, various methods have been proposed for discovering a lesion by detecting the temperature difference.

For example, Special Publication No. 48-33949, Special Publication No. 48-33949,
In Japanese Patent No. 33952, etc., far infrared rays emitted by living tissue are detected to measure the temperature of the inner surface of the living cavity. Furthermore, in Japanese Utility Model Application Publication No. 49-141687 and Japanese Patent Publication No. 53-11157, temperature is measured by inserting a temperature measuring probe through an endoscope and pressing it against the inner surface of the body cavity. be. Further, in Japanese Patent Publication No. 54-18515, temperature is determined by pressing a liquid crystal film against the inner surface of a living cavity and observing the color change of this liquid crystal film.

However, since all of these prior art methods utilize non-transparent far-infrared radiation or heat conduction through contact, they can only measure the temperature of the surface within the body cavity. Therefore, it is difficult to detect submucosal lesions, and of course, it is impossible to detect lesions in areas such as the pancreas or liver where a measuring instrument cannot be inserted.

The present invention was made with attention to the above circumstances, and
The purpose of this invention is to provide a microwave detection device inside a living body cavity that is capable of detecting not only the surface inside the living body cavity but also the state below the surface thereof.

It is generally known that living tissue emits electromagnetic waves depending on its temperature state. As shown in FIG. 1, this radiation spectrum covers a wide frequency range, and the higher the absolute temperature T, the more the radiation intensity increases, reaching its maximum when the wavelength λ in the air is around 10 μm. However, this wavelength region of maximum intensity is far-infrared rays, which has the property of hardly transmitting through living tissue, and cannot detect anything inside the living tissue.

However, in the microwave range, it easily penetrates the living tissue. Therefore, the present invention attempts to measure the temperature state under the mucous membrane by detecting microwaves emitted from the inner surface of the body cavity.

The present invention will be described below based on embodiments shown in the drawings.

Reference numeral 1 in FIG. 2 is an insertion section of a side-viewing flexible endoscope, and a distal end portion 2 of this insertion section 1 is provided with an observation objective optical system 3 for side viewing. Further, an image guide 4 is connected to the observation objective optical system 3, and this image guide 4 is guided through the insertion section 1 to the eyepiece section of the hand operation section. In addition, this insertion part 1
An illumination optical system (not shown) is incorporated into the unit.

A pair of microwave detectors 5 and 6 are provided at the distal end 2 of the insertion section 1 to detect microwaves radiated from living tissue. As shown in FIG.
It is attached so that it can be pushed out from the tip. That is, the distal end portion 2 is provided with an aperture 7 that opens toward the distal end, and a U-shaped leaf spring 9 whose central portion is attached and fixed to a holder 8 is installed within the aperture 7. The microwave detectors 5 and 6 are attached to each end of the leaf spring 9, and an operating wire 10 is connected to the holder 8, and the operating wire 10 passes through the insertion section 1 and connects to the hand operating section. being guided by the side. Furthermore, a ring-shaped guide rod 11 is attached and fixed to the opening periphery of the opening 7, and is adapted to receive the leaf spring 9. That is, the leaf spring 9 is biased so that it is normally open, and is therefore biased so that it slides on the guide rod 11 and projects forward. However, since it is pulled by the operating wire 10, it can be stopped at any arbitrary position. In other words, the microwave detectors 5 and 6 are attached so that they can be pushed and retracted from the tip of the distal end portion 2 by pushing and pulling the operating wire 10 by an operating mechanism installed on the hand operating section side. The microwave detectors 5 and 6 are arranged side by side in the direction of the observation field. When the leaf spring 9 is pulled into the opening 7 by the operating wire 10, both ends of the leaf spring 9 are compressed, the distance between the microwave detectors 5 and 6 is narrowed, and the opening 7 Part of it can be pulled inside. Furthermore, if the leaf spring 9 is pushed out, both ends thereof will expand, causing both the microwave detectors 5 and 6 to protrude and the distance to each other to be widened. In other words, the distance between the microwave detectors 5 and 6 can be selected.

Further, as shown in FIG. 2, a membrane-like elastic body 12 that transmits microwaves is fitted at the tip of the distal end portion 2, and surrounds the microwave detectors 5, 6, etc. on the tip side. ing. Furthermore, the inside of this elastic body 12 can be filled with a liquid 13 having a high dielectric constant, such as water, and this liquid 13 is injected through a liquid injection pipe 14.

On the other hand, the microwave detectors 5 and 6 are equipped with a waveguide 15 that also serves as an antenna, as shown in FIG.
Microwaves incident through the waveguide 15 are absorbed into a cone-shaped absorption medium 16, and a temperature rise in the absorption medium 16 is detected by a thermistor 17 as a change in resistance value. Further, in order to downsize the microwave detectors 5 and 6, the inside of the waveguide 15 is filled with a medium 18 having a high dielectric constant. That is, if the dielectric constant of the medium 18 is ε _r , the wavelength of the microwave is shortened, so the size of the waveguide 15 can be reduced by 1/√ _r . For example, if the frequency of the microwave is 5 GHz, the wavelength of the microwave is 6 cm, and if the medium 18 with ε _r ≒ 100 is selected, the waveguide 15
The dimensions of a rectangular waveguide can be approximately 0.6 cm x 0.3 cm.

The outer surfaces of the microwave detectors 5 and 6 are covered with a heat insulating material 19. This heat insulating material 19 is particularly necessary in the calorimetric measurement method using the thermistor 17.

Further, the electric circuit of this embodiment is as shown in FIG.

That is, the thermistors 17 and 17 of each of the microwave detectors 5 and 6 are connected to the two
A galvanometer 21 for detecting equilibrium is built into the side and the difference in resistance value is provided in the resistor bridge circuit 20.
It is detected by Note that 22 represents a battery, and 23 represents a variable resistor.

Next, the detection principle of the above embodiment will be explained.

By inserting the insertion section 1 into a living body cavity in advance, the microwave detectors 5 and 6 directed toward the living tissue separately detect microwaves from the superficial or deep parts of two adjacent sites. Can be separated and detected. The microwaves incident separately on the two microwave detectors 5 and 6 are absorbed by the absorption media 16 and 16 through the waveguides 15 and 15, respectively, increasing their temperature, and this temperature rise is suppressed by the thermistor 1.
7 and 17, and is detected by the resistance bridge circuit 20 as a difference in resistance value.

In this case, to maximize the output of the carbanometer 21 for detecting equilibrium, the distance from the lesion A existing in the superficial or deep part of the living tissue to the microwave detectors 5 and 6 is L, and the two microwave detection The distance between the detectors 5 and 6 is D, and each microwave detector 5 and 6 is
If the beam spread width is θ and the spread length of the lesion A is l, it is necessary that Lθ≈D≒l hold. That is, in this case, the cones of the beams emitted from the microwave detectors 5 and 6 touch each other on the plane passing through the lesion A, but do not overlap with each other. When one of the microwave detectors 5, 6 detects the lesion A on the plane, the other microwave detector 5, 6 does not detect it. Therefore, the output from the galvanometer 21 is maximized. Furthermore, when scanning the microwave detectors 5 and 6 to see changes in the output, the sensitivity (change) is greatest when Lθ≈l, and the lesion A can be easily discriminated. However, as shown in FIG. 4, the state where the lesion A is located, that is, Lθ≧
In the 2D area, the spreads of the two beams overlap each other near the lesion A, so that a large proportion of the microwaves emitted from the lesion A are incident on both microwave detectors 5 and 6. Therefore, the S/N ratio of the detection output decreases significantly, making it difficult to detect the temperature difference between the lesion A and the normal tissue site. On the other hand, if the lesion A is located between two beam cones that do not overlap, it cannot be detected by each microwave detector 5, 6, and the output cannot be maximized. For example, θ≒40°,
When l≈2 cm, the optimum signal is obtained when D≒2 cm and L≈3 cm, but the S/N ratio drops significantly when L≒6 cm or more.

That is, by detecting the maximum output position by changing θ and L, L can be found using D as a reference (θ is known). Further, if the distance from the microwave detectors 5 and 6 to the surface inside the living body cavity is known by another means, the depth position within the living tissue can be estimated.

In addition, as explained in FIG. 2, if the liquid 13 is injected into the elastic body 12 in which the microwave detectors 5 and 6 are placed, and the elastic body 12 is pressed against the inner surface of the body cavity. The liquid 13 can shorten the wavelength of the microwave. Furthermore, even if there is mucus or sewage in the living body cavity, this can be removed and detected, thereby increasing the accuracy.

Note that the microwave detector in the present invention is not limited to a calorimetry method using a thermistor, and may include a detection method using a crystal diode, and the like. Furthermore, the method for determining the difference between the output values of the microwave detectors 5 and 6 is not limited to the resistive bridge circuit. Furthermore, a microwave detector 5,
A larger number of sensors 6 may be prepared, for example, they may be arranged three-dimensionally and the difference between the outputs may be analyzed to detect a lesion.

As explained above, the present invention inserts a detection probe part into a body cavity and detects microwaves emitted from the inner surface of the body cavity. Even the state can be detected. Therefore, lesions such as early submucosal cancer tumors, which were previously difficult to detect, can be easily detected, and cancers in the pancreas, liver, etc., where it was not possible to directly insert an endoscope, can also be detected from within the stomach. becomes.

Furthermore, since this method detects microwaves from living tissue, unlike diagnosis using X-rays, there is no adverse effect on the living body.

Furthermore, since the present invention detects the relative temperature distribution state within the living tissue, no absolute standard is required. In other words, temperature differences in living tissues can be directly detected and tested accurately, easily, and non-invasively.

[Brief explanation of the drawing]

Fig. 1 is a spectral characteristic diagram of electromagnetic waves emitted by biological tissues, Fig. 2 is a sectional view of the vicinity of the insertion section showing one embodiment of the present invention, Fig. 3 is a front sectional view of the distal end thereof, and Fig. 4 5 is a front sectional view of the same microwave detector, and FIG. 6 is a side view of the same microwave detector. DESCRIPTION OF SYMBOLS 1... Insertion part, 2... Tip part, 5, 6... Microwave detector, 17... Thermistor, 20... Resistance bridge circuit, 21... Calbanometer for equilibrium detection.

Claims (1)

[Scope of Claims] 1. An insertion section that can be inserted into a living body cavity, a plurality of microwave detectors that are provided at the tip of this insertion section and detect microwaves radiated from living tissue, and each of these microwave detectors. What is claimed is: 1. A microwave detection device in a biological cavity, comprising means for detecting a difference in signal output obtained by the two methods. 2. The microwave detector in a living body cavity according to claim 1, wherein the microwave detector is provided so as to be freely inserted and taken out from the tip of the insertion section, and the distance between the microwave detectors is variable. Detection device.