JPS6155378B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a biological tissue hardness measurement method that applies vibration to a living body via a pressure transmission medium and measures the softness or hardness of the living body based on the amount of displacement of the pressure transmission medium and the applied pressure. It is related to the device.

This type of device makes it possible to quantify the hardness of a living body in place of a doctor's palpation, but for obstetrics and measurements of hollow organs, it is necessary to insert a pressure transmission medium inside. For this reason, it is well known to attach a rubber membrane to the tip of a rod attached to the tip of a thin guide wire and apply air vibration to this rod, but the support of the rod and its surrounding structure become complicated, In addition, because the vibration frequency must be lowered in accordance with the weight of the rod, noise from biological micromotions easily enters the measured frequency range, reducing measurement accuracy and making it impossible to obtain frequency characteristics over a wide band. This was also inconvenient in determining the resonance characteristics of.

Therefore, the present invention provides an apparatus for measuring the hardness of biological tissue of the type mentioned at the beginning, which has a simple structure and enables vibration to be applied over a wide range of living organisms of various shapes, and also enables measurement in a wide frequency range. aim to do.

Next, the present invention will be explained based on the illustrated embodiments.

First, the hardness measuring device according to the embodiment of the present invention is as follows:
It consists of a probe that applies vibration to the living body and detects its response signal, a circuit device that processes the detection signal and drives the probe, and an output device that displays or records measured values.

Figure 1 shows one of these probes.
In the figure, reference numeral 1 denotes a vibration adder in the form of a moving coil, for example, which applies vibration to a conical driving body 3 made of a non-magnetic material such as a duralumin plate. A ring 5 made of a non-magnetic material is attached above the container 2, and another ring 6 similarly made of a non-magnetic material is fitted above this. A watertight diaphragm 9 is inserted into a circular gap 8 formed along the inner wall of this ring 6 via an elastic body, and both rings 5, 6
A displacement sensor 11 that detects the amount of displacement of the diaphragm 9 using, for example, a strain gauge is inserted into the gap 10 in a watertight manner. The beam 11' of the displacement sensor 11 is connected to the driving body 3 by a screw 13 with a flat tip along with the diaphragm 9.
Fixed. Further, in the ring 6, a groove 16 to which deaerated water is supplied by a pot 15 and a gap 18 in which a pressure sensor 17 is mounted are communicated from the outer wall to the inner wall. A ring 20 made of a transparent material such as acrylic is further attached to the upper surface of the ring 6 by pasting or using screws from above. This ring 20 is provided with an elastic body 21 halfway from the upper part on its inner wall, so that a lower open pipe 22 made of stainless steel, for example, is removably fitted into the ring 20, and the inner diameter of the ring 20 is set to 6 at the lower end.
matches the inner diameter of The outer diameter of the pipe 22 is, for example, about 10 mm, and the height of the portion protruding from the ring 20 is, for example, 200 mm. Above the pipe 22, an O-ring 23 and a washer 24 are attached to the notch part, and a cap 26 is screwed in with a watertight elastic film, such as a polyurethane film 25, placed on the washer 24. . In the final installed state, the inner end of the pipe 22 presses the elastic membrane 25 higher than the upper end of the cap 26.

FIG. 2 shows the circuit device and output device of the present invention. First, a frequency variable sine wave oscillator 31 and a power amplifier 32 for the oscillation signal are connected to the vibration adder 1.
It constitutes the drive circuit. Also, an amplifier 41 that amplifies the detection signal of the displacement sensor 11, and a high-pass filter 4 that selects only the vibrational displacement signal.
2, a rectifier 43 that converts the vibration component that has passed into a DC signal, a DC amplifier 44, a corresponding amplifier 45 belonging to the pressure sensor 17, a high-pass filter 46, a rectifier 47, and a DC amplifier 48.
and the output signal of the DC amplifier 44 is sent to the DC amplifier 48.
an analog division circuit 49 that divides by the output signal of
a low-pass filter 50 that removes noise generated during the division operation and outputs a compliance signal;
A low-pass filter 51 that passes only the DC component from the output signal of the amplifier 45 and outputs a static pressure signal.
and constitute a signal processing circuit for both sensors 11 and 17. Reference numeral 60 denotes an output device, such as a pen recorder, for displaying, metering, or recording the static pressure and compliance signals generated by this signal processing circuit.

When making measurements, open the pot 15 and add degassed water 2.
8 through the groove 16 into the cylindrical space inside the ring 6 and into the pipe 22, or check the foaming of the degassed water 28 through the transparent ring 20 and remove the pipe 22 as necessary. 2
2 and the rings 6 and 20, and the degassed water 28 is replaced. The compliance equivalent circuit for the vibration system related to the measurement from the drive body 3 to the living body in such a state is as shown in FIG. From the compliance C1 of the vibrating part, the compliance C4 of the living tissue, the compliance C3 of the elastic membrane 25 applied in series to these, and the compliance C2 mainly of the lateral escape of the pipe 22 applied in parallel to these C3 and C4. This results in a series-parallel circuit that cannot be ignored with respect to the compliance C4 of the living body. Therefore, first, the elastic membrane 25 is brought into contact with a rigid body surface so that C4=0, and the value of C2 is determined based on the vibration pressure and vibration amount between points A and A', and then the elastic membrane 25 is The value of C3 is also determined by calculating the combined value of C2 and C3 in a free state, that is, C4=∞. Then, the elastic membrane 25 is applied to the living tissue to obtain a composite value of C2 to C4, and C4 is calculated based on the known values of C2 and C3.

Specifically, first, by setting the frequency of the oscillator 31 and driving the vibration adder 1 with the amplified signal, the driver 3 moves the diaphragm 9 and the screw 13.
vibrates the tip of the degassed water at a set frequency. Therefore, the pressure sensor 17 and the displacement sensor 11 measure the static pressure and static pressure displacement corresponding to the pressing force of the elastic membrane 25 on the object to be measured, as well as the vibration pressure applied to the object and its compliance. Each related vibration displacement amount is detected. First, the detected displacement signal is amplified by an amplifier 41, passed through a high-pass filter 42 to pass only vibration components necessary for compliance measurement, and converted into a DC signal by a rectifier 43.
The signal is further amplified by a DC amplifier 44 and supplied to an analog divider circuit 49 as a divided signal. on the other hand,
A high-pass filter 46 selects only the vibration component of the detected pressure signal, amplifies it, converts it into DC, and supplies it to an analog divider circuit 49 as a divisor signal.
Therefore, the analog divider circuit 49 sequentially and automatically calculates the composite compliance related to the object to be touched, and the low-pass filter 50 outputs a compliance signal. Furthermore, the low-pass filter 51 selects the DC component of the pressure signal output from the amplifier 45, thereby outputting a static pressure signal. The compliance signal and the static pressure signal are supplied to the output device 60, and from their respective amplitudes, the composite compliance beyond the diaphragm 9 for each measurement condition is measured, and at the same time, the static pressure of the degassed water at the time of the measurement is also known. In this way, C2 and C3 are measured in advance over the required frequency band and static pressure range to obtain their respective values.

When measuring the compliance of living tissue, the output device 60 similarly monitors the static pressure to adjust the pressing force of the elastic membrane 25 while C2 to
Measure the composite value of C4 over a predetermined frequency or frequency band, and calculate C4 based on the known values of C2 and C3.
Calculate.

Figure 4 shows that in order to confirm the effect of the hardness measuring device described above, we added an amount of RT silicone rubber additive with similar mechanical behavior to the soft tissue of a living body and changed its stiffness (compliance). The stiffness measurement value changes with high accuracy in response to hardness.
FIG. 5 shows measurements of the resonance characteristics of silicone rubbers having different hardnesses, in which not only the hardness itself but also the resonance point shifted in accordance with the hardness was measured. Figure 6 shows measurement data of frequency characteristics of stiffness on the tibia for two healthy women (solid line) and two female patients with edema (dotted line), confirming that edema can be detected from the hardness and resonance frequency of living tissue. It was done.

The liquid to be filled in the pipe 22 is preferably water, especially degassed water without elasticity, from the viewpoints of viscosity coefficient, easy availability, harmlessness to living organisms, chemical inertness, etc. It is also possible to use other liquids with lower viscosity coefficients. Incidentally, the viscosity coefficient of water is thought to be on the order of 10 ^-4 compared to the sliding viscosity of living organisms, but even liquids on the order of 10 ^-2 can be measured with high precision. As a circuit device, both input signals of the divider circuit 49 can be exchanged to output a stiffness signal, or the output signals of both amplifiers 44 and 48 can be directly added to the output device to perform division separately. can.

Furthermore, it is also conceivable to provide an arithmetic circuit that automatically calculates C4 when C2 and C3 are set, and to use a digital printer that numerically records the values as an output device. Regarding the shape of the pipe, it is also possible to use other shapes instead of a thin tube depending on the measurement location.

As described above, the present invention makes it possible to apply pressure to various biological parts with a simple structure by using a liquid as a vibration transmission medium to the living body, and also makes it possible to measure hardness in a wide frequency range, making it extremely suitable for clinical applications. Meaningful. In particular, since the medium pipe can be formed into a thin tube shape, it can also be applied to measurements of the hardness of the cervix in the field of obstetrics.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the probe portion of the hardness measuring device according to the present invention, Fig. 2 is a block diagram showing the circuit configuration of the circuit device and output device portion, and Fig. 3 is a cross-sectional view of the probe portion of the hardness measuring device according to the present invention. 4 to 6 show measurement data for confirming the effects of the present invention. 1... Vibration adder, 3... Drive body, 5, 6, 20...
Ring, 9...Diaphragm, 11...Displacement sensor, 17...Pressure sensor, 22...Pipe, 25...Elastic membrane.

Claims (1)

[Claims] 1. A pipe having an elastic membrane at its tip and filled with a liquid having a viscosity coefficient lower than that of a living body;
It is characterized by having a vibration adder that applies vibration to the liquid from the rear of the pipe via a diaphragm, a displacement sensor that detects the amount of displacement of the liquid, and a pressure sensor that detects the pressure of the liquid. A device for measuring the hardness of living tissues. 2. The biological tissue hardness measuring device according to claim 1, wherein the liquid is water.