JP2001070334A - Ultrasonic irradiation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic irradiation apparatus capable of accurately controlling an ultrasonic vibrator through the output control due to the measurement of power or temp. SOLUTION: An ultrasonic irradiation apparatus consists of an ultrasonic applicator 1 constituted of a plurality of ultrasonic vibrators 2 for irradiating the desired region in a subject with ultrasonic waves, a drive means 11 for applying voltage and a current to the ultrasonic vibrators 2, a voltage/current measuring means 18 for measuring the values of the applied voltage and current and a power operation means 16 for calculating a power value from the measured voltage and current values. The power operation means 16 calculates the power value on the basis of the product of the difference between the voltage values and that between the current values measured with respect to two or more vibrator pieces discriminated so that the respective drive modes thereof are different in a plurality of the ultrasonic vibrators 2. In addition to this, a temp. measuring means is provided to the applicator 1 and the ultrasonic vibrators 2 may be controlled on the basis of the output result thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic irradiation apparatus for treating a tumor or the like in a living body using ultrasonic waves.

[0002]

2. Description of the Related Art In recent years, in the field of medicine, it has been emphasized to improve the quality of life (QOL) of patients after surgery, and to achieve this philosophy, minimally invasive treatment (Minimall
y Invasive Treatment (MIT) is gaining attention. One example is the practical use of an “extracorporeal shock wave calculus crushing device”. This device crushes and treats calculus without surgical operation by irradiating a strong shock wave from outside the body to a calculus inside the body, and has changed the treatment method for urological stones.

On the other hand, the above-mentioned MIT has also attracted attention in the field of cancer treatment. In particular, in the case of cancer, since most treatments rely on surgical operations, the functions and appearance of the organs are often greatly impaired, and even if the life is prolonged, a great burden is imposed on the patient. Therefore, development of a minimally invasive treatment (apparatus) in consideration of QOL is strongly desired.

[0004] In such a trend, hyperthermia therapy has been developed which heats cancer cells to cause necrosis. this is,
This is a treatment method for selectively killing cancer cells by heating and maintaining the affected area at 42.5 ° C. or higher by utilizing the difference in heat sensitivity between tumor tissue and normal tissue. In particular, for a tumor deep in a living body, a method using ultrasonic energy with a high penetration depth has been considered as disclosed in, for example, JP-A-61-13955. Further, as shown in, for example, US Pat. No. 5,150,711, the above-mentioned heat treatment method is further advanced to focus the ultrasonic waves generated by the ultrasonic vibrator on the affected part to heat the tumor part, thereby causing heat degeneration necrosis. Treatments that cause it to occur are also being considered. In this therapy, the degree of thermal denaturation and the size of the region are determined according to the ultrasonic energy and the irradiation time.

As described above, the ultrasonic energy (quantity) is an important factor for determining the degree of necrosis of an affected part, but it is usually difficult to actually measure the area to be treated. I have. For this reason, in measuring the specific amount of the irradiation ultrasonic energy, the electric energy input to the ultrasonic vibrator has been conventionally used as an index thereof. Therefore, the technique relating to the measurement of the electric energy is an important technique when an effective treatment is to be performed, and the measurement accuracy is generally expected to be high. Incidentally, in the present situation, a means is employed in which the voltage applied to the ultrasonic vibrator and the current flowing therethrough are measured, and the power supplied to the ultrasonic vibrator is determined from the multiplication result with the phase. In general, the input / output impedance of the power meter and the characteristic impedance of the cable are usually “50Ω”. Therefore, only when the impedance of the ultrasonic vibrator is 50Ω, a normal power meter is used. The power supplied to the ultrasonic vibrator can be obtained by using this. Note that this “5
The specific value “0Ω” is an impedance value that is considered to have the highest transmission efficiency in a coaxial cable, and is generally known in electric transmission engineering (transmission line theory).

[0006]

However, according to the above method, the voltage applied to the ultrasonic vibrator and the flowing current are measured directly, so that the ultrasonic waves reflected from the inside of the subject are not reflected by the vibrator. , The electromotive force generated by exciting was also measured at the same time, and could not be separated. Therefore, the power obtained from the multiplication result with the phase by the voltage and the power measured as described above is not pure power supplied to the ultrasonic transducer, but the voltage and current components due to the electromotive force as errors. It is superimposed and has a problem that accurate measurement is difficult. Also, of course,
It has also been difficult to perform accurate drive control of the ultrasonic transducer.

[0007] Excitation of the vibrator caused by reflected ultrasonic waves also makes it impossible to measure power using a normal wattmeter. This is because, as described above, the power meter can be used only when the input impedance of the vibrator connected to the power meter is matched to 50Ω from the viewpoint of the power meter. However, even if the impedance is initially adjusted to 50Ω, the “apparent” impedance of the vibrator changes when the vibrator is excited for the above-described reason. As a result, therefore, a commonly used wattmeter could not be used, and even if used, accurate power could not be measured.

[0008] In addition, in the case of a device using a piezo element, which is a typical ultrasonic transducer, the following problems are pointed out. That is, its electro-acoustic conversion efficiency (the efficiency of converting the input electric energy into irradiation ultrasonic energy)
Is generally about 40 to 50%, which means that electric energy that is not converted as ultrasonic energy is converted into heat energy, and that the piezo element generates heat. On the other hand, the piezo element has an irreversible upper temperature threshold that can operate as a vibrator. More generally, the allowable heat generation temperature of the ultrasonic vibrator is naturally determined in consideration of the heat resistant temperature of the support, the attachment, the adhesive, and the like of the ultrasonic vibrator. That is, the piezo element is basically required to be used at a temperature lower than the temperature determined as described above, or otherwise, accurate operation of the ultrasonic transducer cannot be expected.

Therefore, conventionally, a temperature sensor is arranged in the vicinity of the ultrasonic vibrator to measure the temperature, and when the heat is generated above a certain temperature threshold, the ultrasonic irradiation is stopped. However, since only one kind of temperature threshold for stopping the operation with respect to the heat generation temperature of the ultrasonic vibrator is usually set, operation stop and return may be discontinuous near this temperature due to external noise or the like. Further, there is a problem that the operation is stopped because the temperature of the ultrasonic vibrator immediately exceeds the threshold value after the re-operation.

Further, the impedance of the ultrasonic vibrator,
It is known that the resonance frequency changes with temperature. For this reason, when the vibrator temperature increases in accordance with the ultrasonic irradiation, there is a problem that the total irradiation energy actually applied to the living body differs from the total irradiation energy planned at normal temperature.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to accurately control the driving of an ultrasonic vibrator through output control by power measurement or output control by temperature measurement. It is an object of the present invention to provide an ultrasonic irradiation device capable of performing the following.

[0012]

The present invention employs the following means in order to solve the above problems.

That is, an ultrasonic irradiation apparatus according to a first aspect of the present invention includes an ultrasonic generator including a plurality of ultrasonic vibrators for irradiating a desired part in a subject with ultrasonic waves, and the ultrasonic vibrator. Driving means for applying a voltage and current to, voltage and current measuring means for measuring each of the applied voltage value and current value, power calculation means for obtaining a power value from the measured voltage value and current value, Wherein the power calculation means comprises, among the plurality of ultrasonic transducers, two or more transducer pieces that are distinguished such that their driving modes are different,
The power value is obtained based on a product of a difference between a voltage value and a current value measured for each of the vibrator pieces.

In the ultrasonic irradiation apparatus according to the first aspect, in the second aspect, the driving mode may relate to a mode of an output waveform from the driving unit. 4. The device according to claim 3, wherein each of the vibrator pieces is driven with a different phase and amplitude of the output waveform, wherein the driving mode relates to an output energy mode of the driving unit, and 5. The apparatus according to claim 4, wherein each of the one or more vibrator pieces is driven with a different degree of attenuation of the output energy, and the driving mode relates to a mode of the output energy of the driving unit. Each of the two or more vibrator pieces is characterized in that the output energy is distributed and driven at a different rate.

According to a fifth aspect of the present invention, in the ultrasonic irradiation apparatus according to any one of the first to fourth aspects, a means for controlling an output of the driving means is further added, and the ultrasonic power is obtained by the power calculating means. The output of the driving means is controlled based on the power value.

According to a sixth aspect of the present invention, there is provided an ultrasonic irradiation apparatus, comprising: an ultrasonic generator configured to irradiate an ultrasonic wave to a desired portion in a subject; And a driving unit for applying a current, and a temperature measuring unit for measuring a temperature of a predetermined portion inside or near the ultrasonic generating source, and controlling the driving unit based on a measurement result of the temperature measuring unit. And control means.

According to a seventh aspect of the present invention, in the ultrasonic irradiating apparatus according to the sixth aspect, when the temperature measured by the temperature measuring means exceeds a first temperature threshold value, the control means may control the drive. The driving means is made operable when the means is stopped or the output is restricted and when the temperature falls below the second temperature threshold value.

An ultrasonic irradiation apparatus according to an eighth aspect of the present invention is the ultrasonic irradiation apparatus according to the seventh aspect, further comprising a cooling means for cooling the ultrasonic generation source, wherein the first temperature threshold and the second temperature threshold are set. The temperature difference is represented by a function of one or more of an output of the driving unit, an output time, and a cooling capacity of the cooling unit.

According to a ninth aspect of the present invention, in the ultrasonic irradiating apparatus according to the seventh or eighth aspect, the temperature difference between the first temperature threshold and the second temperature threshold is any one of an ultrasonic irradiation intensity and an irradiation time. Or represented by one or more functions.

According to a tenth aspect of the present invention, in the ultrasonic irradiation apparatus according to any one of the sixth to ninth aspects, an output, an output time, and an output frequency of the driving means according to an output of the temperature measuring means. Controlling at least one of them.

According to an eleventh aspect of the present invention, there is provided an ultrasonic irradiation apparatus according to any one of the sixth to tenth aspects, wherein the ultrasonic irradiation apparatus is inserted between the driving means and the ultrasonic source to perform load matching. And means for controlling the matching condition of the matching means in accordance with the output of the temperature measuring means.

According to a twelfth aspect of the present invention, there is provided an ultrasonic irradiating apparatus comprising: an ultrasonic generating source comprising a plurality of ultrasonic vibrators for irradiating a desired part in a subject with ultrasonic waves; Driving means for applying voltage and current to the temperature, temperature measuring means for measuring the temperature of a predetermined portion inside or near the ultrasonic generator, and a characteristic value corresponding to the temperature of the ultrasonic transducer It is characterized by comprising storage means for storing, and control means for selecting the characteristic value based on the temperature measured by the temperature measuring means and controlling the driving means.

The ultrasonic irradiation apparatus according to the thirteenth aspect of the present invention provides the ultrasonic irradiation apparatus according to the first to fifth, sixth to eleventh, or first aspects.
2 is characterized by being configured by combining any two or more of them.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment in which the present invention is applied to an ultrasonic irradiation apparatus for inducing a tumor into heat death by intense ultrasonic waves. In the figure, a therapeutic ultrasonic applicator (ultrasonic generator) 1 includes a plurality of piezoelectric element groups (ultrasonic transducers) 2 arranged on a spherical surface such that the wavefront of the generated ultrasonic wave is concave, It is composed of an imaging ultrasonic probe 3 inserted and arranged at the center of the piezoelectric element group 2 and a flexible coupling film 4. An ultrasonic wave propagating substance 5, for example, well degassed water is sealed in the coupling film 4.

Here, the imaging ultrasonic probe 3
Can be used in a well-known mechanical scan type or electronic scan type. As shown in FIG. 1, the imaging ultrasonic probe 3 is connected to an ultrasonic imaging device 8, reconstructs a tomographic image of the inside of the subject 6, and renders it on the display unit 9. The drawn tomographic image is used for the purpose of confirming the position of the ultrasonic wave generated from the piezoelectric element group 2 described below in order to accurately irradiate the treatment target 7 in the subject 6 with the ultrasonic wave. Become.

The applicator 1 includes the coupling film 4
Is brought into contact with the subject 6 via. Then, the treatment ultrasonic waves (strong ultrasonic waves) are emitted from the piezoelectric element group 2 toward the treatment target 7. As shown in FIG. 2, the piezoelectric element group 2 in the present embodiment includes two sets of fan-shaped vibrator pieces 2 for convenience.
a and 2b are provided, and these are arranged alternately on a spherical surface. In this specification, the terms “piezoelectric element” or “vibrator” are used depending on the case, but in any case, these terms are considered to be essentially synonymous. No two terms are intended to produce a particularly significant difference.

By the way, the above-described configuration in which the vibrator pieces 2a and 2b are separately provided makes it possible to perform ultrasonic irradiation by the "focus expansion method" by separately controlling the phases. It is. Here, briefly,
The “focal point expansion method” will be described. This is based on the above-described piezoelectric element group 2, which is a set of vibrator pieces 2 a including a plurality of piezoelectric elements, and another set of similar vibration elements. As shown in FIG. 2, the two vibrator pieces 2a and 2b are separately controlled in phase with respect to the element piece 2b (by the driving means 11, the phase inverting means 12, the waveform generating means 13 (described later) or the like in FIG. 1). ), The ultrasonic focus point is determined at one “point” in the normal ultrasonic irradiation, and the focus point forms a focal point which is enlarged in the periphery, and the range in which the ultrasonic energy acts is wider. It is made to become something. This makes it possible to improve the therapeutic effect on the treatment target 7. Further, distinguishing the piezoelectric element group 2 into the two sets 2a and 2b makes it possible to drive and control each of them as described above. However, in the present invention, separately from the above embodiment, The piezoelectric element group 2 may be configured such that all of the individual transducers are captured as independent elements, and these are individually driven and controlled.

The piezoelectric element group 2 is composed of vibrator pieces 2a, 2a.
b, via the voltage / current measuring means 18 according to each of
It is connected to a load matching means 10 for performing impedance matching, and the load matching means 10 is further connected to a driving means 11. The driving unit 11 supplies power required for generating ultrasonic waves to the piezoelectric element group 2. The driving means 11 also
The output of the waveform generating means 13 is connected to the input of the phase inverting means 12. The phase inversion means 12 controls the inversion and non-inversion of the output phase of the wave generated from the waveform generation means 13. The substantial determination of the phase inversion / non-inversion is controlled by a signal from the control unit 14.

The control means 14 also controls the output amplitude of the driving means 11, the output frequency and waveform of the waveform generating means 13, the display mode of the display means 9, and the matching conditions of the load matching means 10. Further, the control means 14 is provided via the input means 15
The operator inputs a set value, a control value, and the like.

Here, the waveform generating means 13 includes:
A normal analog oscillation circuit or a PLL circuit may be used, or a waveform may be digitally synthesized, and a sine wave may be obtained using a DA converter and a low-pass filter.

The power calculating means 16 receives the measured value from the voltage / current measuring means 18 and obtains the power supplied to the piezoelectric element group 2 by a calculating circuit or calculating means based on the value. Then, the power value obtained by the power calculation means 16 is sent to the control means 14. The control means 14
The output of the driving unit 11 and the matching condition of the load matching unit 10 are adjusted so that the set value and the actual output value are equal to each other within an allowable range by comparing with the output set value stored in the storage unit 17 in advance.

Next, a description will be given of a calculation of a power value in the piezoelectric element group 2 according to the first embodiment using the ultrasonic irradiation apparatus having the above configuration, and a method of controlling the applied power based on the calculation result.

When power is applied to the piezoelectric element group 2 and ultrasonic waves are irradiated toward the inside of the subject 6, the ultrasonic waves are reflected by various ultrasonic reflectors in the living body. Here, considering the situation where the ultrasonic wave reflected from one point other than the focal point is incident on the piezoelectric element group 2 surface, the area of the piezoelectric element group 2 surface is large, and the reflected wave incident on it is Various components having different phases are incident, and as a result, on the surface of the piezoelectric element group 2, these reflected waves all cancel each other out, and no large electromotive force is generated. The same is true even if a reflector located at a different position is assumed (this case is also assumed to be other than the focal point), and eventually no large electromotive force is generated.

On the other hand, considering the reflected wave from near the focal point,
The reflected waves reflected in various directions from the vicinity of the focal point enter the two surfaces of the piezoelectric element group 2 with almost the same phase. Therefore, if the high-reflecting body of the ultrasonic wave is at the focal point, a large reflected wave is incident on the piezoelectric element group 2, and as a result, the vibrator is greatly excited, and a large electromotive force is generated. The voltage and current value due to the electromotive force may be several tens of percent of the applied voltage. Therefore, the electromotive force due to the reflected wave causes a large error in the calculated power value.

Therefore, it is impossible to accurately measure the power of the electromotive force generated with respect to the reflected wave from the vicinity of the focal point unless some measure is taken. However, in the first embodiment, the following is required to realize this. Take such measures.

Since the reflected waves incident on the piezoelectric element group 2 come from all directions in the subject 6, for example, the levels and phases of the reflected waves incident on the vibrator pieces 2a and 2b at adjacent positions are very similar to each other. It will be. For example, even when ultrasonic waves having different phases and waveforms are applied to the individual transducers, the levels and phases of the reflected waves incident on the transducer pieces 2a and 2b at adjacent positions are very similar to each other. Therefore, in the first embodiment, it is considered that these are offset.

Now, it is assumed that ultrasonic irradiation is performed by applying the focus expansion method by phase control. That is, in this case, as shown in FIG. 2, the driving waveforms of the adjacent transducer pieces 2a and 2b are in the opposite phases and have different amplitudes. Therefore, assuming that the measured voltage of the vibrator piece 2a is VA and that of the vibrator piece 2b is VB, VA = Va + v (1) VB = −Vb + v (2) where Va and Vb are the vibrators, respectively. Pieces 2a and 2
The voltage applied to b, v is the voltage induced by the reflected wave.

When the measured value of the current flowing through the vibrator piece 2a is IA and the measured value of the current flowing through the vibrator piece 2b is IB, IA = Ia + i (3) IB = -Ib + i (4) Where Ia and Ib are the transducer pieces 2a and 2a, respectively.
The current i flowing through b is the current induced by the reflected wave.

Then, the following calculation is performed using the above equations (1) to (4).

(VA−VB) × (IA−IB) = (Va + Vb) × (Ia + Ib) (5) Here, the ratio defined between Va and Vb and between Ia and Ib is known in advance. When this is set to k, Vb = kVa (6) Ib = kIa (7) When these equations (6) and (7) are substituted into equation (5), (1 + k) ² × Va × Ia ... (A). Since k is known in advance, the power (Va × Ia) in which the influence of the voltage v and the current i induced by the reflected wave is canceled (or eliminated) is finally obtained from the above equation.

Next, consider the case of ordinary ultrasonic irradiation without applying the focus enlarging method.

In the same manner as described above, the vibrator pieces 2a,
For 2b, VA = Va + v (8) VB = Vb + v (9) Here, Va is usually equal to Vb, but in this case, since the power value cannot be obtained by cancellation as in Expression (5), ultrasonic irradiation is performed with Va と し て Vb.
In order to achieve this, as shown in FIG. 1, the a-channel and the b-channel are driven by different driving means 11,
Each drive output (output level) is made different, or as shown in FIG. 3A, an attenuating means 31 is inserted into one of the drive outputs of the a-channel or the b-channel.
Alternatively, as shown in FIG. 3B, one drive output is divided into a divider 3 having a different distribution ratio between two channels.
By inserting 2, different outputs may be distributed to the a channel and the b channel.

In these cases, the two vibrator pieces 2a, 2b
Are driven with the same phase and different energies or levels, but if the difference in the driving energies is not so large, the influence on the properties of the focal sound field is extremely small. On the other hand, in order to cancel v due to the reflected wave, the difference between Va and Vb may be very small. In practice, it is sufficient if there is a sufficiently large difference based on the variation of v. In other words, Va−Vb >> δv is sufficient. Here, δv represents the variation of v.

As described above, firstly, the measurement voltages VA and VB having opposite phases and different amplitudes to be obtained when the focus enlarging method is applied, and secondly, by normal ultrasonic irradiation. Measurement voltages VA and VB when different drive outputs are to be obtained in the case, measurement voltages VA and VB in which one has undergone different output attenuation, or measurement voltages VA in which one and the other are output and distributed at different distribution ratios. , VB
(In each case, the measured currents IA and IB are also measured.) In order to obtain the actual power value from them, equation (5) is applied to cancel v or i, and (A) It can be seen that equation (3) should be applied.

In order to actually perform the above calculation, the above-described power calculation means 16 and voltage / current measurement means 1 are used.
For example, one having a circuit as shown in FIG.

In FIG. 4, the voltage and current waveforms picked up by the voltage / current measuring means 18 are used for the power calculating means 1.
6, the difference between the a and b channels of these voltages and currents is calculated by the adder 41, and the result is input to the multiplier 42 to obtain the result. By the way, the multiplier 42
Thereafter, the low-pass filter 43 is connected, the signal in the high-frequency part is cut off, and only the low-frequency part is treated as a signal constituting the power value. In addition,
The power calculating means 16 in the first embodiment is realized by an analog electronic circuit as described above. In some cases, the voltage and current waveforms picked up by the voltage / current measuring means 18 are converted to A and B. It is also possible to obtain a power value by performing a / D conversion to digitize the data and calculating the result by a computer.

From the above description, it can be pointed out that in the first embodiment, a normal voltage waveform probe or a current waveform probe can be used as the voltage / current measuring means 18 shown in FIG. .

Next, a method of stabilizing the output by using the measured power value will be described with reference to FIG.
FIG. 5 is a configuration example of a circuit forming a part of the control unit 14. In FIG. 1, the power value derived by the power calculation means 16 has been input to the control means 14. The output power set value is stored in the storage unit 17 via the input unit 15 in advance.

As shown in FIG. 5, the set power value stored in the storage means 17 is compared with the actually measured value measured by the power calculation means 16 by a comparator, and if the measured value is smaller than the set value, Then, the output increase signal which is the comparator output is turned to the plus side, and if the measured value is larger than the set value, the output increase signal is turned to the minus side. When the set value and the measured value are exactly equal, the output increase signal becomes zero. Here, a gain adjustment circuit is inserted in the driving means 11, and the gain is increased by the output increase signal, and is decreased if the output increase signal is negative. On the other hand, if the output increase signal is zero, the gain is kept constant. In this way, the output power is stabilized at a preset value.

As described above, in the first embodiment, in the conventional power measurement of the piezoelectric element group 2, the excitation electromotive force caused by the reflected ultrasonic waves generated in the piezoelectric element group 2 is used. Although the measurement has been performed at the same time, an accurate measurement of the power value can be performed by eliminating the influence by canceling out the influence. In addition, if the accurate power measurement is used as a background, accurate output power control can be performed, so that accurate and reliable treatment of the treatment target 7 can be performed.

Next, a second embodiment of the present invention will be described. The second embodiment relates to an invention made on temperature control of the piezoelectric element group 2. In other words, as described in the section of the related art, in general, when the temperature of the piezoelectric element group 2 becomes higher than a predetermined value, accurate output control becomes impossible, and in addition, the deterioration of the element becomes difficult. In the worst case, the piezoelectric element group 2
The environment in which the piezoelectric element group 2 operates is monitored and maintained at a temperature equal to or lower than the predetermined temperature, since the housing material and the adhesive for supporting the piezoelectric element may cause abnormalities such as melting and deterioration.
There will be a need to control. In the second embodiment,
The purpose is to do this properly.

FIG. 6 shows an outline of an ultrasonic irradiation apparatus according to the second embodiment. In FIG. 6,
The point that a temperature measuring means 60 is newly provided is different from that of FIG. Therefore, in FIG. 6, the components denoted by the same reference numerals as those in FIG. 1 operate as described above, and the description thereof will be omitted.

The temperature measuring means 60 includes a measuring probe 60a.
The measurement probe 60a is provided at an appropriate place for measuring the temperature of the piezoelectric element group 2, more specifically, an ultrasonic wave propagation medium sealed inside the piezoelectric element group 2, that is, in the coupling film 4. 5 is attached to the surface in contact with the well degassed water (or the opposite surface). For example, a thermistor may be used as the measurement probe 60a. The thermistor is a component having a property that the resistance value decreases as the temperature increases, and can measure the temperature of an object to be measured by being combined with a constant voltage source.

FIG. 7A shows an example of a circuit configuration inside the temperature measuring means 60. The comparator 51A has a threshold T1.
The output becomes L at a temperature equal to or higher than the (first temperature threshold), and the comparator 51B outputs a threshold T2 satisfying the condition of T2 <T1.
The output becomes H at a temperature equal to or lower than the (second temperature threshold). The flip-flop 71 operates to latch the output of the comparator 51A and reset the output by the output of the comparator 51B. Here, T1 and T2 are the comparators 5
R1, R2, R3 connected to the inputs of 1A and 51B,
And R4. Note that R2 and R4 are variable resistors, whose resistance is changed by a control signal from the control means 14. Here, for a predetermined temperature of T1, | T1-T2 |
And the temperature difference between T2 and T2 are controlled so as to be determined depending on the set output of the drive means 11 and the set output time. Therefore, the larger the set output and the longer the set output time, the lower the temperature of T2. These controls are performed by the control unit 14. On the other hand, FIG. 7 (b) shows an example of a well-known circuit in which T1 and T2 can be set by one comparator 51. By changing the values of the feedback resistor Rf and the input resistor Ri, T1 and T2 are changed. Changes are possible.

The control means 14 controls the load matching inserted between the driving means 11 and the ultrasonic applicator 1 as shown in FIG. The matching condition of the means 10 is controlled. As a result, it becomes possible to follow the matching condition of the piezoelectric element 2 that changes as the temperature rises or falls.

In the ultrasonic irradiation apparatus according to the second embodiment having such a configuration, the temperature measuring means 60 measures the temperature of a predetermined portion of the piezoelectric element group 2 in the applicator 1 as described below. And an operation related to the control of the ultrasonic irradiation.

That is, when the temperature detected for the predetermined portion of the piezoelectric element group 2 exceeds the threshold value T1,
The high-intensity ultrasonic waves from the piezoelectric element group 2 are suppressed as compared with the previous output, and the output is limited. Ultrasonic irradiation is in a state of “under temperature control” or “temperature monitoring”. In the irradiation under the temperature control, specifically, the measurement result of the temperature measurement unit 60 is output to the control unit 14, and based on the output, the control unit 14
By controlling at least one of the output energy or level, the output time, and the output frequency.

When the detected temperature is lower than T1 by a threshold T2.
When the temperature of the element has dropped to the normal level, normal irradiation is restarted. That is, at the time of irradiation under temperature control, the next normal irradiation can be started while waiting for the temperature of the piezoelectric element group 2 to decrease to T2.

From the above, first, the piezoelectric element group 2 in the second embodiment is irradiated under temperature control in an environment where the temperature is equal to or higher than the threshold value T1, so that the piezoelectric element group 2 Unnecessary excessive temperature rise does not occur, and abnormal occurrence such as deterioration and destruction of the piezoelectric element or melting and deterioration of the housing material and the adhesive can be prevented. By the way, it goes without saying that a treatment for stopping the ultrasonic irradiation itself may be adopted instead of the irradiation under the temperature control.

In the second embodiment, the above T
Since the threshold value T2 is determined in addition to 1, the following effects can be obtained. In other words, if the threshold value is one, the next moment when the device temperature rises and the temperature control works and the ultrasonic irradiation is controlled, the device temperature decreases and returns to the normal operating temperature range. The normal irradiation and the temperature control irradiation are repeated in a short time, for example, the ultrasonic irradiation is performed and the temperature threshold is immediately exceeded. In other words, the flicker operation is performed. This eliminates the frequent repetition of normal ultrasonic irradiation and irradiation under temperature control.

When the detected temperature exceeds the threshold value T1, the next normal irradiation is not performed until the temperature decreases to the threshold value T2.
It is also possible to provide a temperature threshold T3 defined as T3 <T1, and to return to the normal irradiation when the temperature drops to the threshold T3. In this case, the time until the normal irradiation is shortened.

For example, when the ultrasonic irradiation apparatus is actually used, if there is a preset time in which only the ultrasonic irradiation must be performed, or the ultrasonic irradiation time is desired to be performed within the shortest total time. In such cases, it can be seen that the introduction of T3 is an effective measure.
Regarding the temperature T2 at this time, it is sufficient to wait for the element temperature to drop to T2 before performing the next irradiation after the end of the set time or the total time.

By the way, in the above configuration, when the detected temperature exceeds the threshold value T1, the control means 14 directly controls the driving mode (output level and the like) of the piezoelectric element group 2; Along with or instead of this, a cooling unit (not shown) for cooling the piezoelectric element group 2 may be separately provided. In this case, the control unit 14 determines whether the cooling unit can be operated based on the threshold value T1 or the threshold value T2.

In the second embodiment, the use of a thermistor as the temperature probe 60a has been described in the above description of the structure. However, the present invention is not limited to this. A temperature probe specific to various types of temperature measurement, such as an optical fiber or an optical fiber, may be used.
The temperature probe 60a is mounted on a predetermined portion of the piezoelectric element group 2. However, the temperature probe 60a is mounted on the surface of the imaging ultrasonic probe 3, the propagation medium 5, and the coupling film 4 as well.
The inside of the applicator 1 may be measured, for example, inside.

Further, the temperature difference between T1 and T2 has been determined above depending on the set output and the set time. In addition, the temperature difference may be determined by the ultrasonic irradiation intensity, the irradiation time, or the cooling means described above. May be expressed as a function of the cooling capacity of the piezoelectric element based on the above. Even in this case, it is clear that safe and more reliable ultrasonic irradiation is possible. The same applies to the newly introduced T3. In this case, both T2 and T3 may be functions of the ultrasonic irradiation intensity, the irradiation time, and the cooling capacity.

In addition, here, T1, T2 and T3 are introduced as symbols representing "temperature". However, when relating to cooling capacity, etc., T1, T2 and T3 are considered as "time" and the same as above. An ultrasonic therapy apparatus according to another embodiment may be configured.

Next, a third embodiment of the present invention will be described. Since the third embodiment is realized by an apparatus having the same configuration as that shown in FIG. 6, it will be described with reference to FIG.

In FIG. 6, the storage means 17 stores in advance the characteristic values of the piezoelectric element group 2 corresponding to the temperature.
Here, the “characteristic value corresponding to the temperature” generally means that characteristics such as resonance frequency and impedance change as the temperature of the piezoelectric element group 2 rises. Beforehand, the characteristics of the piezoelectric element group 2 are kept constant irrespective of the temperature, even if any of the above-mentioned various characteristic changes occurs. Is a correction value obtained to maintain the characteristic of

The control means 14 includes a temperature measuring means 60
The temperature information of the piezoelectric element group 2 measured by the above is compared with the characteristic value of the piezoelectric element group 2 stored in the storage means 17, and the output signal frequency of the waveform generating means 13 and the load matching of the load matching means 10 are compared. Adjust the conditions. Further, the signal amplification factor of the driving unit 11 is derived from the set output value and the characteristics of the piezoelectric element group 2 stored in the storage unit 17. In this way, even when the temperature of the piezoelectric element group 2 changes, it is possible to control the output ultrasonic wave intensity to be constant.

As described above, conventionally, when the piezoelectric element group 2 is driven under the frequency and load matching conditions set at room temperature, the output becomes higher as the temperature of the piezoelectric element group 2 becomes higher. When it was inevitable that the sound wave intensity deviated from the set value, the temperature measuring means 6
0, the temperature of the piezoelectric element group 2 is monitored, and a characteristic value corresponding to the temperature stored in the storage unit 17 is selected and corrected based on the measured temperature information. The strength can always be kept constant.

It should be noted that the characteristic values corresponding to the temperatures are obtained by experimentally driving the piezoelectric element group 2 in advance in various temperature environments, and obtaining the output frequency, the matching condition, and the like corresponding to the various temperatures. And if they can be "expressed" in some form as a function of temperature,
The function or expression may be stored in the storage means 17, and the control of the driving means may be determined by substituting the measured temperature into the storage means 17. The above-mentioned “selection of characteristic values” includes the above concept.

[0073]

As described above, according to the ultrasonic irradiation apparatus of the present invention, first, the output waveform and the output energy are applied to two or more vibrator pieces with different modes, and each of them is measured. Since the power value is obtained by canceling the applied voltage value and current value, the effect of the excitation by the reflected ultrasonic wave is eliminated, so that accurate power measurement can be performed, and thus, accurate output control of the ultrasonic transducer is performed. can do.
At this time, for the same reason as described above, when measuring the voltage and the current, a normal voltage waveform probe and a current waveform probe can be used.

Further, by providing the temperature measuring means,
For an ultrasonic transducer that is desired to operate at a certain temperature or lower, it is possible to prevent the overheating thereof in advance, and in addition to the first temperature threshold for the purpose of preventing the overheating, the second temperature Since the threshold value is introduced, a so-called flicker operation can be prevented. Therefore, this also contributes to accurate output control of the ultrasonic transducer.

Further, with respect to the change in the characteristic of the ultrasonic transducer depending on the temperature, the characteristic value is stored in advance, and the characteristic value is compared with the temperature measured by the temperature measuring means. Select an appropriate value from the values
By performing the correction, an accurate operation of the ultrasonic transducer can be realized at any temperature.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration example of an ultrasonic irradiation device according to a first embodiment.

FIG. 2 is a schematic diagram of a configuration example of a piezoelectric element group 2 divided into two sets of vibrating bars 2a and 2b, and an explanatory diagram showing drive waveforms for each of the vibrating bars 2a and 2b.

FIG. 3 is a diagram showing an example in which two sets of vibrating reeds 2a and 2b are respectively driven by channels a and b associated with each other in a different manner. FIG. In each case, FIG. 2 (b) shows a case where two channels are provided with a distributor which performs an appropriate distribution with respect to the output.

FIG. 4 is a schematic diagram showing a circuit configuration example of a power calculation unit shown in FIG. 1;

FIG. 5 is a schematic diagram illustrating a circuit configuration example of an output increase signal.

FIG. 6 is a schematic diagram illustrating a configuration example of an ultrasonic irradiation device according to a second embodiment.

7 is a schematic diagram showing an example of a circuit configuration of the temperature measuring means shown in FIG. 6, wherein FIG. 7 (a) and FIG. 7 (b) each have similar temperature hysteresis characteristics, but have different forms; It is.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic applicator (ultrasonic source) 2 Piezoelectric element group (ultrasonic transducer) 3 Ultrasonic probe for imaging 4 Coupling film 5 Propagation substance (water) 6 Subject 7 Treatment target 8 Ultrasonic imaging device 9 Display Apparatus 10 Load matching means 11 Driving means 12 Phase inversion means 13 Waveform generation means 14 Control means 15 Input means 16 Power calculation means 17 Storage means 18 Voltage / current measurement means 31 Attenuation means 32 Distributor 41 Adder 42 Multiplier 43 Low pass filter (LPF) 50 Comparator 60 Temperature measuring means 71 Flip-flop 72 Reference voltage

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4C099 AA01 CA13 GA30 JA13 4C301 AA02 CC01 EE11 EE19 FF24 FF26 GC02 GC15 GC22 GC27 HH01 HH02 HH04 JB38

Claims (13)

[Claims] An ultrasonic generator configured to irradiate a desired part in a subject with ultrasonic waves, the ultrasonic generator including: a plurality of ultrasonic transducers;
Driving means for applying a voltage and current to the ultrasonic transducer, voltage and current measuring means for measuring each of the applied voltage value and current value, and obtaining a power value from the measured voltage value and current value And a power calculation unit, wherein the power calculation unit is, among the plurality of ultrasonic transducers,
For two or more vibrator pieces that are distinguished such that their driving modes are different, the power value is obtained based on the product of the difference between the voltage value and the current value measured for each of the vibrator pieces. An ultrasonic irradiation device characterized by the above-mentioned. 2. The driving mode relates to a mode of an output waveform from the driving unit, and each of the two or more vibrator pieces is driven as one having a different phase and amplitude of the output waveform. The ultrasonic irradiation device according to claim 1, wherein 3. The driving mode relates to the mode of the output energy of the driving unit, and each of the two or more vibrator pieces is driven as having a different degree of attenuation of the output energy. The ultrasonic irradiation device according to claim 1, wherein 4. The driving mode relates to a mode of an output energy of the driving unit, and each of the two or more vibrator pieces is driven by distributing the output energy at a different ratio. The ultrasonic irradiation device according to claim 1. 5. An apparatus according to claim 1, further comprising means for controlling an output of said driving means, and controlling an output of said driving means based on said power value obtained by said power calculating means. 5. The ultrasonic irradiation device according to any one of items 1 to 4. 6. An ultrasonic generating source comprising a plurality of ultrasonic transducers for irradiating a desired part in a subject with ultrasonic waves,
A driving unit for applying a voltage and a current to the ultrasonic transducer, and a temperature measuring unit for measuring a temperature of a predetermined portion inside or near the ultrasonic generating source, and a measurement result of the temperature measuring unit. Control means for controlling the driving means based on the control signal. 7. The control unit, when the temperature measured by the temperature measurement unit exceeds a first temperature threshold, stops the drive unit or puts the output into a state of limiting the output, and lowers the temperature below a second temperature threshold. 7. The ultrasonic irradiation apparatus according to claim 6, wherein said driving means is made operable. 8. A cooling unit for cooling the ultrasonic generating source, wherein a temperature difference between the first temperature threshold and the second temperature threshold is an output of the driving unit, an output time, or a temperature of the cooling unit. The ultrasonic irradiation apparatus according to claim 7, wherein the ultrasonic irradiation apparatus is represented by any one or more functions of the cooling capacity. 9. The method according to claim 7, wherein a temperature difference between the first temperature threshold and the second temperature threshold is represented by a function of one or more of ultrasonic irradiation intensity and irradiation time. The ultrasonic irradiation device according to any one of the above. 10. The apparatus according to claim 6, wherein said control means controls at least one of an output, an output time, and an output frequency of said driving means according to an output of said temperature measuring means. The ultrasonic irradiation device according to any one of the above. 11. An alignment unit, which is inserted between the driving unit and the ultrasonic wave generating source to perform load matching,
11. The ultrasonic irradiation apparatus according to claim 6, wherein the control unit controls a matching condition of the matching unit according to an output of the temperature measuring unit. 12. An ultrasonic generating source comprising a plurality of ultrasonic transducers for irradiating a desired part in a subject with ultrasonic waves, and driving means for applying a voltage and a current to the ultrasonic transducers; Temperature measuring means for measuring the temperature of a predetermined portion inside or in the vicinity of the ultrasonic generating source, storing means for storing a characteristic value corresponding to the temperature of the ultrasonic vibrator, and the temperature measuring means Control means for controlling the driving means by selecting the characteristic value based on the measured temperature. 13. A method according to claim 1, wherein
13. An ultrasonic irradiation apparatus according to claim 12, wherein any two or more of the ultrasonic irradiation apparatuses are combined.