JPS60199429A - In vivo temperature measuring apparatus - 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] The present invention is an instrument for measuring thirst in a living body, in particular, transmitting and receiving ultrasonic pulse waves within a subject and analyzing and processing the reflected echoes from a predetermined test site. This invention relates to an improved device that can non-invasively measure the temperature inside a living body.

[Prior art] It has been put into practical use in various treatment devices, especially hyperthermia (warming therapy), to increase the temperature of hot water within the body by applying wave energy to the body using ultrasonic waves, microwaves, or RF waves. In recent years, it has attracted particular attention as an effective treatment method for malignant tumors.

However, such heating treatments have a large effect on living tissues and may even cause necrosis of normal tissues, and it is extremely difficult to accurately measure the temperature of living tissues during such heating treatments. It was important.

However, with conventional devices, it has been almost impossible to accurately measure the condition of the deep part of the subject in a non-invasive manner. Currently, the method currently in use is to insert a thermocouple into the subject, but such conventional invasive methods cause extensive pain to the subject and may also lead to the formation of malignant tumors. During treatment, there were major problems such as the risk of cancer cells metastasizing to other normal tissues when the thermal lightning pair was inserted and removed.

1. Purpose of the Invention The present invention was made in view of the above-mentioned conventional problems, and its purpose is to provide an improved device capable of non-invasive and accurate temperature measurement.

[Structure of the Invention] In order to achieve the above object, the present invention transmits and receives an ultrasonic pulse wave inside a subject, and the desired subject area obtained at this time (
We memorize the reflection J'- before and after heating, and use the fact that the sound speed of ultrasound inside the subject differs depending on the time difference of the received waveform and the rise in temperature. It is characterized by measuring the temperature inside the body from this sound speed difference.

That is, as is well known, the body temperature of adults is extremely constant except for the body surface, and is usually maintained at around 37°C. Therefore, it is understood that the sound velocity of the ultrasonic waves passing through each tissue within the living body is also constant.Therefore, when a living body is heated, the sound speed within the body changes by the amount of this heating. By analyzing the reflection of the pulsed waves transmitted into the body and calculating the sound velocity ratio before and after heating each tissue phase, it is possible to non-invasively measure the temperature inside the cow's body or to perform edema. It becomes possible to know the distribution.

In the past, it has been proposed to measure the change in the speed of sound when the temperature rises, but such conventional devices attempt to measure the speed of sound itself, and such measurement of the absolute sound speed is extremely inner-axis. Until now, it has not been possible to put it into practical use.

The principle of the present invention will be briefly explained above.

Figure 1 shows the progress and reflection status of ultrasonic pulses when in-vivo tissue is considered to be a layered tissue. J, II- is reflected from the interface of each tissue.

Figure 2 shows the reflection signal when an ultrasonic pulse is transmitted to the three-layered tissue described above, and Figure 2 shows the reflection signal that is applied before heating. -3-, and FIG. 2B shows the reflected echo signal after humidification. The horizontal axis is time, and the vertical axis is the reflected echo signal intensity.J0 First, the reflected echo signals before heating are P+ SP? , P3, and P+, and the intervals between these pulse waves are shown as τ1, τ2, and τ3.

When the sound velocity of each tissue before heating is expressed as Cbn, the following equation is obtained.

τI4Q+ /Cb + , τ2 =2+112 /
Cb2.

τ3・2Q3/C113・・・・・・(1) Similarly,
Reflector after heating]-signal P+', P2', P
3' and P+', the timing of generation of the reflected echo signal differs depending on the change in the sound speed of each tissue, and the intervals τ1', τ2', τ, and τ between each pulse wave change, respectively. If the sound velocity after heating is Can, then τl'=2Ω+/Cat, τ2'=2<12/C, similar to equation (1).
a2.

ri'=2Qi/Cai *+*+·-121 is obtained.

If the difference in each interval τ before and after heating is expressed as Δτ-4-, the sound velocity ratio before and after heating in each layer structure is expressed as follows, Ca+ /C1l+ -rl /τ1'・τ1/(τ1
−Δτ2 ) = 1 / (1−Δτ2/τI ) Ca 2 /Cb 2 = r2/r2'−τ2/(τ
2-(Δτ3-Δτ2))=1/(1-(Δτ3
−Δτ2)/τ2) Ca 3 /Cb3 = r3/r
3'・τ3/(τ3-(Δτ鴫−△τ3))=1
/(1-(Δτ噌−Δτ3)/τ3) When these are converted into a film, the formula (3) is obtained.

Can/C1ln=rn/rn'=
1/(1-(Δτ0+1-Δτ0)/τ0) ...(
3) As is clear from this equation (3), it is understood that the time difference between the reflected echoes of each part of the object indicates the sound speed ratio before and after heating.

On the other hand, as mentioned above, the sound velocity of living tissue is 3.
It is known that in the temperature range of about 5°C to 45°C, it can be approximately approximated to a linear function of temperature.

Therefore, it is now possible to express linear characteristics as shown in the following equation, where the sound speed is a function of Ci and 1 degree is a function of T1.

C1=θ·T giant α (4) However, here, θ and α are constants determined by lI′116I in the living body.

Now, let the temperature of the living tissue before heating be Tb (approximately 31°C), let the temperature after heating be Ta, and calculate the ratio T of the sound velocity Ca after 110 degrees and the sound velocity cb before heating, γ -Ca/Cb
=i・Ta+α)/i・1−b+α)=
(Ta→(a7θ))/(TbI(alo)). Therefore, if this ratio T is used, the temperature of the living tissue after heating is given by the following equation.

Ta = 7Tb+(7-1) α/θ −−・(5
) In this equation (5), the sound speed ratio γ is determined from the time difference as described above, and the value of α/θ is determined by the biological tissue, so it is understood that it is sufficient to measure a unique value for each tissue. be done. For example, as the value of α/θ,
Water is approximately 865, kidney is 1220-1230,
As mentioned above, the lagoon temperature before heating can usually be approximated to 37°C.

Therefore, according to the above equation (5), it can be concluded that very easy, non-invasive and accurate in-vivo measurements can be made using the sound velocity γ before and after heating.

[Description of Embodiments] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 3 shows an example of the in-vivo collapse machining apparatus according to the present invention. is possible.

As is well known, ultrasonic pulses are transmitted from an electronic scanning transducer 10 toward a subject, and in the embodiment, the ultrasonic pulses are linearly scanned. This wave transmission control is performed by the wave transmission controller 12, and the reflected echo from the subject is converted into an electrical signal by the transducer 10, and then the wave reception controller 14 performs scanning tIlI on the reception side.
-7- Both controllers 12,14 receive control commands from the central controller 16.

Similar to the normal 8-mode ultrasonic diagnostic equipment, the wave receiving controller 1
The reflected echo signal of No. 4 is subjected to contrast compression and other nonlinear amplification processing by the logarithmic amplifier 18, and is further processed by the A/
r) After being converted into a digital signal by the converter 20, it is stored in the image memory 22. And this image memory 22
The digital image signal stored in is added to the temperature/sub signal, which is a feature of the present invention described later, in an adder 24, and then converted to an analog signal in a D/A converter 26 and sent to an image monitor television 28. A predetermined image display is obtained.

FIG. 4 shows an example of such an image on the monitor television 28.

On the other hand, the output of the logarithmic amplifier 18 is also branched and supplied to a waveform memory 30 for temperature measurement according to the present invention, and a predetermined reflection signal is stored therein. The waveform memory 30 itself includes an A/D converter, captures the reflected echo signal as a digital value, and stores and holds this in a first memory. Furthermore, the waveform memory 3
0 has a second memory in which reflected echo signals similar to those described above can be separately stored, whereby the waveform memory 30 can be used at different timings, i.e. It becomes possible to separately store and hold different reflected echo signals before and after.

Both the stored signals before and after heating, which the waveform memory 30 has, are supplied to a time difference detector 32, and based on the control action of the central controller 16, the time difference before and after heating, that is, Δ
Add τ. Further, this time difference is subjected to a calculation corresponding to the above-mentioned equation (31, (5)) in the temperature calculation unit 34, so that a predetermined temperature change can be calculated.

In the embodiment, since both pieces of stored information in the waveform storage 30 are divided into two parts in the depth direction during the rimbling process, the temperature calculator 34 calculates the temperature change in each divided section. You can output this once 71
〜stored in the risk memory 36 and added to the adder 2 described above.
4 can be supplied. Therefore, the output from the adder 24 can modify both the image information from the image memory 22 and the temperature information from the matrix memory 36.
Temperature changes can be displayed on the image, for example, as a color display.

In this embodiment, heating control for hyper4nomia on the living body is also performed in synchronization with the image and moisture display using the ultrasonic pulses described above, and the wave transmitting controller 12 and the wave receiving controller 14, the heating wave transmission controller 38 activates the heating irradiator 40 to irradiate a desired part of the living body with heating ultrasonic waves, etc., and keep the malignant tumor and other parts at a predetermined temperature. I can write.

The embodiment according to the present invention has the above configuration, and the fourth embodiment is as follows.
．． The operation will be explained with reference to Figure 5.6.

As described above, while displaying the B-mode image shown in FIG. 4, the central controller 16 commands the tissue region to be measured by position specifying means such as a joystick, as shown by the broken line in FIG. Set. In the embodiment, this set area is the depth (Ld - Lo), and corresponds to TU to Q as the time of reflection J.

After the temperature measurement area is designated in this way, the foul echo signal sequence in the area before heating is transmitted to the logarithmic amplifier 1.
8 to the first memory in the waveform storage unit 30. In the embodiment, it is preferable that this acquisition signal is not performed for the total reflection echo of the linear scan, but at a predetermined sampling interval. Q) is set to an interval obtained by dividing the former into 1 equal part, and for example, it is preferable that the sampling distance in the depth direction is about τ: 51111. Then, actual information acquisition is performed by a distance in the depth direction that is shorter than such a sampling interval, for example, δ,1 to 1°6III.

Therefore, the ringing signal t in the designated area before heating is a signal @P+, P2, P3, . . . -P as shown in FIG. 6A.

It is understood that

Next, after the pre-warming reflection signal has been memorized, the warming irradiator 40 performs a predetermined warming action on the subject, and after a predetermined period of time, In the same manner as described above, the repulsion process after heating is performed. - Signal acquisition is performed.

FIG. 6B shows the state of capture of reflection: r-D-(No. 8) after heating, and after heating, unlike sampling before heating, the output of the logarithmic amplifier 18 is scanned at each scan. line(
(no, n5, n10), the captured signal is compared with the reflected echo signal before heating, and the corresponding portions of the signals are stored in the second memory. Of course, if there is no movement in the test area before and after heating the living body, the obtained reflected echo signal itself should correspond to the living tissue and should be similar, and this can be compared sequentially. If the deviation is detected, it is possible to find a signal that has almost the same shape as the reflected echo information sampled before heating, and such comparative measurements can be performed using correlation methods, Fourier analysis, etc. For example, it is possible to capture the information that the signal has shifted slightly in the distance direction (in the direction of the inter-part axis) due to the temperature difference. Become.

Then, the two types of reflected echo signals before and after heating, which are captured in the waveform memory 30 in this way, are processed by the time difference detector 32, and the time difference Δ at each timing is
τ can be obtained, and based on these, the temperature calculator 34
By performing calculations corresponding to the above-mentioned equations (3) and (5), the average temperature for each sampled hourly timing can be calculated, and this can be stored in the matrix memory 36. Therefore, if such processing is performed on the entire depth within the selected area and this is supplied to the adder 24 as a color signal corresponding to temperature, etc., the monitor television 2
8, a superimposed display of a B-mode image and an image colored according to temperature can be obtained.

In the embodiment described above, an example was shown in which two memories were provided in the waveform memory 30, but the reflected echo information before heating is stored in advance in a single memory, and the logarithmic amplifier 18 It is also possible to simultaneously perform analysis and comparison processing while supplying the reflected echo signal from the heating hole to the sequential Y waveform memory 30, and to sequentially output the time difference for each timing.

[Effects of the Invention] As explained above, according to the present invention, since the speed of sound varies depending on the temperature increase of the propagation medium of the ultrasonic pulse, the temperature of the living body can be accurately and non-invasively measured by measuring this high speed ratio. At 8
1. It is extremely useful for hyperthermia, etc.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the reflection effect of ultrasonic waves on layered tissue, Fig. 2 is a detected waveform diagram of reflected echoes before and after heating to demonstrate the principle of the present invention, and Fig. 3 is a diagram showing the principle of the present invention. FIG. 4 is an explanatory diagram showing an example of the image of the television monitor shown in FIG. 3 (); FIG. FIG. 6 is an explanatory diagram of the operation of the embodiment shown in FIG. 3. 10 ... Electronic scanning transac-1-12 ・
... Wave transmission controller 14 ... Wave reception controller 16 ... Medium heat controller 28 ... Image monitor television 30 ... Waveform storage device 32 ... Time difference detector 34 ... Temperature Reactor 40: Irradiator for heating. Applicant Aloka Co., Ltd. 16-

Claims (1)

[Claims] (1) An ultrasonic transducer that transmits ultrasonic pulse waves into the subject and receives reflected echoes from internal tissues; A waveform memory device that captures the signal, a time difference detector that compares the corresponding reflected echo waveforms before and after heating and detects the time difference; and a temperature calculator for calculating the internal temperature of the subject after heating, and measures the internal temperature of the subject after heating per sweat based on the sound velocity ratio of the ultrasonic pulse waves before and after heating. Internal body temperature measuring device.