JP2004024668A - Transcranial ultrasonic therapy apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new transcranial ultrasonic therapy apparatus of for heads which can dissolve thrombus in a cerebral artery by irradiating it with ultrasonic waves from outside of the head. <P>SOLUTION: The transcranial ultrasonic therapy apparatus 10 consists of an ultrasonic probe 11 for irradiating the head of a therapy objective person A with the ultrasonic waves; a high-frequency oscillator 12 for generating high-frequency current of 250 kHz to 850 kHz; a controller 13 for controlling the high-frequency oscillator 12, or the like; and a cooler 15 for cooling an ultrasonic irradiation surface of the ultrasonic probe 11. The ultrasonic probe 11 is brought into close contact with one of the outer sides of the head of the person A, and the high-frequency current outputted from the high-frequency oscillator 12 under control by the controller 13 is supplied to the ultrasonic probe 11. The controller 13 controls output of the high-frequency current to control ultrasonic output and intermittently supplies the high-frequency current to intermittently irradiate the ultrasonic wave to the head of the person A for dissolving the thrombus. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transcranial ultrasonic therapy apparatus, that is, an ultrasonic therapy apparatus that irradiates ultrasonic waves from outside the head to dissolve thrombus generated in blood vessels in the brain and hematomas outside the blood vessels.
[0002]
[Prior art]
Research on therapeutic methods that attempt to dissolve blood clots and hematomas generated in blood vessels by irradiating ultrasound to the human body was started in the 1980's. A catheter was inserted into a blood vessel, and ultrasound was irradiated from the tip of the catheter. Catheterization to dissolve blood clots and hematomas. At the same time in the 1980's, a therapeutic method using a combination of a thrombolytic agent and ultrasonic irradiation by a catheter method was proposed.
[0003]
In addition to the catheter method, the present applicant has proposed a transcranial cerebral artery thrombolysis method, that is, a method of irradiating ultrasonic waves from outside the head to dissolve thrombus in the cerebral artery. Proposed a percutaneous coronary artery thrombolysis method, i.e., a method of irradiating the heart with ultrasound from outside the human body to dissolve the thrombus in the coronary artery. Has been confirmed to be effective by animal experiments.
[0004]
However, the former method of transcranial cerebral artery thrombolysis, that is, the method of dissolving thrombus in the cerebral artery by irradiating ultrasonic waves from outside the head, causes attenuation of ultrasonic waves in the skull in tissues such as skin and muscle. The effectiveness could not be confirmed sufficiently, for example, due to the reason that the irradiated ultrasonic waves were difficult to reach the target thrombus portion with a sufficient intensity because the attenuation was larger than the attenuation.
[0005]
[Problems to be solved by the invention]
The present applicant further pursued the applicability of the transcranial cerebral artery thrombolysis method, and as a result, the following problems to be solved became clear.
[0006]
First, there is a lack of irradiation power due to attenuation of ultrasonic waves at the skull. It is well known that when ultrasonic waves are irradiated from outside the head, the ultrasonic waves are attenuated while transmitting through the skull, and the amount of attenuation is determined by the vibration frequency (MHz) of the ultrasonic waves. It is related to bone thickness (cm) and is set to 45 dB / cm / MHz.
[0007]
When this is converted into the thickness of the temporal bone 2 mm, which is said to be the thinnest bone, it becomes 9 dB / MHz, and when the vibration frequency of the ultrasonic wave is 1 MHz or more, it becomes 35% or less of the irradiation power, and the attenuation is too large, The results for soft tissues such as muscles are difficult to apply to skulls. On the other hand, when the vibration frequency of the ultrasonic wave is 1 MHz or less, the attenuation is not so large and approaches the case of soft tissue such as muscle.
[0008]
Second, the temperature inside the living tissue increases due to the ultrasonic irradiation. When the living tissue is irradiated with ultrasonic waves, the ultrasonic energy is absorbed by the living tissue, and the temperature inside the living tissue increases. The temperature rise TI can be approximately expressed by the following equation (1).
[0009]
TI = Pfc ÷ 210 (1)
Here, P: sound pressure of ultrasonic wave fc: vibration frequency of ultrasonic wave, that is, the higher the vibration frequency of ultrasonic wave, the larger the temperature rise of the living tissue. An increase in the temperature of living tissue, especially in the case of the head, has fatal consequences. It is considered unfavorable when the body temperature exceeds the normal value of 37 ° C. and rises to 39 ° C. or higher, and particularly unfavorable for brain tissue in which blood flow in peripheral blood vessels is interrupted by a thrombus.
[0010]
Also, the absorption of ultrasonic energy in bone is particularly large as compared with the absorption of soft tissue, and even with ultrasonic irradiation in an ultrasonic diagnostic apparatus, the temperature rises to 10.5 ° C. or more with irradiation of 0.5 W / cm ^2. And the cerebral cortex near the inner surface of the skull is likely to cause a dangerous situation.
[0011]
Third, the influence of the tearing pressure of the cell membrane due to the ultrasonic irradiation. Since ultrasonic waves are compression waves, they act as a force to tear the cell membrane when the pressure swings to the negative side. This tear pressure Pr becomes stronger as the vibration frequency of the ultrasonic wave becomes lower even with the same ultrasonic energy, and the tear pressure Pr and the vibration frequency f are expressed by the following formula (2). There is a relationship shown.
[0012]
Pr = MI / (f) ^1/2 (2)
Here, MI is an index (constant) determined by the structure of the probe, and will be referred to as a mechanical index in the following description.
[0013]
That is, the tear pressure Pr = MI at the vibration frequency f = 1 MHz, the tear pressure Pr = MI / (10) ^{1/2 at} the vibration frequency f = 10 MHz, and the tear pressure Pr = MI / (0) at the vibration frequency f = 100 kHz. .1) ^1/2 , the lower the vibration frequency of the ultrasonic wave, the higher the possibility of damaging the cells.
[0014]
Fourth, ensuring safety against ischemic brain cells. It is said that when blood flow in peripheral blood vessels is interrupted by a thrombus, supply of oxygen or glutamate to brain tissue becomes impossible, and necrosis of damaged cells related to the blood brain starts several minutes later.
[0015]
In this situation, even if the thrombolysis treatment of the cerebral artery by ultrasonic irradiation is performed, acceleration of metabolism due to the temperature rise of the brain tissue due to the ultrasonic irradiation and cell destruction due to the tearing pressure of the cell membrane due to the ultrasonic irradiation It is important to avoid.
[0016]
Summarizing the problems described above, when irradiating ultrasonic waves to living tissues, the higher the vibration frequency of the ultrasonic waves, the greater the temperature rise of the living tissues, and the lower the vibration frequency of the ultrasonic waves, the more likely it is that the cells will be damaged. Will be higher.
[0017]
Therefore, when developing a treatment device that irradiates ultrasonic waves to a living tissue, the higher the vibration frequency of the ultrasonic waves, the greater the temperature rise of the living tissue, and the lower the vibration frequency of the ultrasonic waves, the higher the possibility of damaging cells. In consideration of the conflicting condition, it is required to determine the vibration frequency of the ultrasonic wave in a range that can prevent the temperature rise and cell destruction of the living tissue.
[0018]
[Means for Solving the Problems]
In the present invention, the vibration frequency of the ultrasonic wave to be irradiated is limited to 250 kHz to 850 kHz, and the temperature rise of the living tissue is suppressed by intermittent irradiation of the ultrasonic wave and cooling of the ultrasonic probe, thereby solving the above problem.
[0019]
The invention according to claim 1 is a transcranial ultrasonic therapy apparatus that transmits ultrasonic waves through the skull and dissolves emboli of intracranial cerebral blood vessels, and an oscillator that generates a high-frequency current of 250 kHz to 850 kHz, An ultrasonic probe that excites a vibrator based on a high-frequency current from an oscillator and projects ultrasonic waves having a frequency of 250 kHz to 850 kHz, and a drive that intermittently supplies a high-frequency current output from the oscillator to the ultrasonic probe Control means and cooling means for cooling the surface temperature of the ultrasonic irradiation section of the ultrasonic probe to a predetermined temperature range are provided.
[0020]
Further, the ultrasonic probe is an ultrasonic probe that projects a non-convergent ultrasonic beam in which the ultrasonic beam does not converge on a specific portion.
[0021]
Further, the drive control means may control the high-frequency current output from the oscillator by an intermittent cycle in which a sub-cycle consisting of a supply period T1 and a supply suspension period T2 is repeated n times, and then suspended for a pause period T3 to make one cycle. A high frequency current is supplied to the ultrasonic probe.
[0022]
The high-frequency current supply period T1 in the drive control means may be 2 minutes, the supply stop period T2 may be 30 seconds, the number of sub-cycles repeated n may be 4 times, and the pause period T3 may be 5 minutes.
[0023]
The cooling unit is a cooling unit that is controlled so as to maintain the surface temperature of the ultrasonic irradiation unit of the ultrasonic probe within a temperature range higher by 2 ° C. than the standard body temperature.
[0024]
The cooling means may be a cooling means for circulating a cooling liquid inside the ultrasonic probe for cooling.
[0025]
Further, the cooling unit may be a cooling unit that cools by energizing a Peltier effect element disposed inside the ultrasonic probe.
[0026]
Further, the transcranial ultrasonic therapy apparatus includes an ultrasonic probe support device that presses the ultrasonic probe to the head and adheres the ultrasonic probe to the head.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. FIG. 1 is a conceptual diagram illustrating a basic configuration of a transcranial ultrasonic therapy apparatus. The transcranial ultrasonic therapy apparatus 10 includes an ultrasonic probe 11 that irradiates an ultrasonic wave to the head of a subject A, and 250 kHz to 850 kHz. A high-frequency oscillator 12 that generates a high-frequency current, a control device 13 that forms a drive control unit that controls the high-frequency oscillator 12, and a cooling device 15 that forms a cooling unit that cools the ultrasonic irradiation surface of the ultrasonic probe 11. You.
[0028]
During the treatment by the transcranial ultrasonic therapy apparatus 10, as a monitoring device for monitoring the therapeutic effect on the treatment target A, the head of the treatment target A is irradiated with the monitoring ultrasonic wave and the reflected wave is detected. A monitoring ultrasonic probe 31 and an ultrasonic monitoring device 32 that supplies a high frequency current of a predetermined frequency to the monitoring ultrasonic probe 31 and analyzes a received reflected wave are used. The probe 31 and the ultrasonic monitoring device 32 do not constitute the present invention.
[0029]
The outline of the thrombolysis treatment by the transcranial ultrasound therapy apparatus 10 will be described. First, the ultrasonic probe 11 is brought into close contact with one outside of the head of the subject A, for example, outside the vicinity of the temporal bone, which is said to be the thinnest in bone thickness, with an appropriate pressure contact force. Further, in order to monitor the therapeutic effect, the monitoring ultrasonic probe 31 is brought into close contact with the outside of the head opposite to the ultrasonic probe 11 with an appropriate pressing force.
[0030]
Under the control of the control device 13, a high-frequency current of a predetermined frequency determined to be optimal for treatment is generated from the high-frequency oscillator 12 from a frequency in the range of 250 kHz to 850 kHz from the high-frequency oscillator 12 and supplied to the ultrasonic probe 11 via the control device 13. To irradiate ultrasonic waves. At this time, the control device 13 controls the output of the ultrasonic wave emitted from the ultrasonic probe 11 to an output determined to be optimal for the treatment, and controls the high frequency current supplied to the ultrasonic probe 11 to ON / OFF control. The probe 11 is intermittently driven to intermittently irradiate the head of the subject A with ultrasonic waves.
[0031]
The monitoring ultrasonic probe 31 irradiates an ultrasonic wave having a frequency different from that of the ultrasonic wave radiated for the treatment, for example, 2 MHz to the head of the treatment subject A and receives a reflected wave of the ultrasonic wave. The condition of the blood flow is monitored by the device 32 to confirm the effect of the thrombolysis treatment.
[0032]
The ultrasonic probe 11 will be described. The ultrasonic probe 11 that irradiates the head of the treatment subject A with ultrasonic waves has the same basic configuration as a known ultrasonic probe, and excites a vibrating body based on an input high-frequency current of a predetermined frequency. And a structure for irradiating an ultrasonic wave having a frequency corresponding to the generated high-frequency current. The ultrasonic probe 11 is configured to irradiate a non-convergent ultrasonic beam because it is not necessary to converge the ultrasonic wave to be irradiated to a specific part (treatment part).
[0033]
The ultrasonic probe 11 has a cooling liquid circulation pipe for cooling the surface of the ultrasonic irradiation unit therein, and a cooling liquid supplied from a cooling device 15 outside the ultrasonic probe 11 is provided. In addition to having a circulating configuration, the temperature sensor 14 for detecting the surface temperature of the ultrasonic irradiation unit is provided.
[0034]
Further, the ultrasonic probe 11 is brought into close contact with an appropriate position of the head of the treatment subject A by using an ultrasonic probe support device (not shown). As the ultrasonic probe supporting device, a device having a known configuration can be used, and for example, a device having a configuration described in Japanese Patent No. 1828229 or the like according to the present applicant's invention can be used.
[0035]
The cooling device 15 controls the temperature of the coolant while controlling the temperature of the coolant so that the temperature detected by the temperature sensor 14 on the surface of the ultrasonic irradiation unit is maintained at a temperature higher by 2 ° C. than the standard body temperature. It is preferable to control the temperature so that the temperature does not exceed 39 ° C. in terms of the temperature in the living tissue. The configuration of the cooling device adopts a known configuration.
[0036]
The relationship between the surface temperature of the ultrasonic irradiation unit and the temperature in the living tissue is measured in advance by experiment and arranged in the form of a conversion table. In actual treatment, the ultrasonic wave detected by the temperature sensor 14 is used. It is preferable to estimate the temperature in the living tissue from the surface temperature of the irradiation unit.
[0037]
The cooling device 15 for cooling the ultrasonic probe 11 has a configuration in which a cooling liquid is supplied from the outside to the cooling liquid circulation pipe for cooling, and a Peltier effect element is arranged near the ultrasonic irradiation part of the ultrasonic probe 11. A configuration utilizing the Peltier effect for cooling by supplying a current to the Peltier effect element, and other configurations can be adopted. In the cooling device 15 using the Peltier effect element, the current supplied to the Peltier effect element is controlled based on the temperature detected by the temperature sensor 14.
[0038]
A configuration other than the above may be employed for the cooling device 15, and a known configuration may be employed for the configuration and the temperature control, and thus detailed description will be omitted.
[0039]
The detection result of the surface temperature of the ultrasonic irradiation unit is monitored by a control device 13 described below to control the temperature of the cooling device 15 and to display a warning as necessary.
[0040]
The reason for cooling the surface of the ultrasonic irradiation section of the ultrasonic probe 11 is as described in the above-mentioned problem. That is, the temperature in the living tissue rises due to the ultrasonic irradiation, and the higher the vibration frequency of the ultrasonic wave, the greater the temperature rise. An increase in the temperature of the living tissue, especially in the case of the head, has a fatal effect, and it is not preferable that the body temperature rises above the normal value of 37 ° C. to 39 ° C. or higher, and in particular, blood flow in peripheral blood vessels due to thrombus. Is not preferred for disrupted brain tissue.
[0041]
The high-frequency oscillator 12 operates under the control of the control device 13 and can generate a high-frequency current in a frequency range of 250 kHz to 850 kHz. The oscillation circuit itself of the high-frequency oscillator 12 uses a known circuit.
[0042]
FIG. 2 is a block diagram illustrating a circuit configuration of the control device 13. The control device 13 includes a control unit 21, an amplifier 22, and a switching circuit 23.
[0043]
The control unit 21 includes a CPU, and sets an oscillation frequency setting unit 21a that sets the oscillation frequency of the high-frequency oscillator 12 to a desired frequency, and an output that sets the amplitude (intensity) of the electric vibration output from the high-frequency oscillator 12 to a desired amplitude. An intensity setting unit 21b, a drive time setting unit 21c that controls ON / OFF of a switching circuit 23 that intermittently supplies a high frequency current output from the high frequency oscillator 12 to the ultrasonic probe 11, and a temperature detected by the temperature sensor 14. And a control panel 21e.
[0044]
The control unit 21 can use a known personal computer, and the amplifier 22 and the switching circuit 23 are also known circuits.
[0045]
The high-frequency oscillator 12 is connected to the oscillation frequency setting unit 21a of the control unit 21, and sets the oscillation frequency based on the oscillation frequency data input from the operation panel 21e. The amplifier 22 is connected to the output intensity setting unit 21b of the control unit 21, and sets the amplification degree based on the output intensity data input from the operation panel 21e. The setting of the oscillation frequency and the amplification degree of the high-frequency oscillator 12, that is, the magnitude of the output will be described later in detail.
[0046]
The switching circuit 23 is connected to the drive time setting unit 21c of the control unit 21, and is controlled to be ON / OFF based on time data input from the operation panel 21e. The drive time set by the drive time setting unit 21c, that is, the ON / OFF control of the switching circuit 23 is set as follows. This is merely an example, and may be changed as appropriate depending on the judgment of the therapeutic effect or the like.
[0047]
The ON / OFF control of the switching circuit 23 is an intermittent cycle in which a sub-cycle consisting of the supply period T1 and the supply suspension period T2 is repeated n times, and then is suspended only for the suspension period T3 to make one cycle.
[0048]
According to the experimental results described later, good results were obtained when the supply period T1 was 2 minutes, the supply suspension period T2 was 30 seconds, the number n of sub-cycle repetitions was 4, and the pause period T3 was 5 minutes.
[0049]
Here, the relationship between the oscillation frequency of the high-frequency oscillator 12, that is, the frequency and the intensity of the ultrasonic vibration radiated from the ultrasonic probe 11, and the relationship between the intensity of the ultrasonic vibration and the temperature rise of the living tissue will be described.
[0050]
According to the experiment, the thrombolysis effect is higher as the frequency is lower if the intensity of the ultrasonic vibration is the same. However, when the intensity of the ultrasonic vibration increases, cavitation (cavity) is generated in the living tissue, and the cell tissue is destroyed. Since the limit intensity of the ultrasonic vibration at which cavitation occurs is mechanical index MI = 1.0 or more, the intensity of the ultrasonic vibration is indicated by an index MI value.
[0051]
At MI = 1.0, the cell tissue is destroyed. Therefore, the allowable safety strength of the ultrasonic vibration is set to MI = 0.25 or less by multiplying by an appropriate safety coefficient, here １ ／. .
[0052]
A safety standard value of 0.72 W / cm ² for the output of the U.S. Food and Drug Administration (FDA) ultrasonic diagnostic apparatus in consideration of safety to living tissue is set as the maximum irradiation power, and MI = 0 from the above equation (2). When the usable limit frequency (lower limit value) of the ultrasonic vibration which becomes .25 is calculated, the frequency f becomes 270 kHz.
[0053]
When the intensity of the ultrasonic vibration to be irradiated is increased, the limit frequency increases, and when the intensity is reduced, the limit frequency can be expanded to a lower frequency.
[0054]
The temperature rise of the living tissue is related to the intensity and frequency of the ultrasonic vibration, and the temperature increases as the intensity and frequency of the ultrasonic vibration increase. Since the effect on the living tissue due to the temperature rise can be represented by the difference from the normal temperature of the living tissue, an index indicating the temperature difference when the normal temperature difference of the living tissue is 0 ° C. is defined as a thermal index TI. , The temperature difference is indicated by an index TI value.
[0055]
FIG. 3 is a diagram showing the results of experimentally confirming the relationship among the intensity, frequency, mechanical index MI, and thermal index TI of ultrasonic waves. The horizontal axis indicates the frequency (MHz) of the ultrasonic vibration, the vertical axis indicates the mechanical index MI and the thermal index TI (° C.), and the ultrasonic output is 0.72 W / cm ² (safety standard value), and the output is higher than this. Is low at 0.5 W / cm ² .
[0056]
The “safety limit” in FIG. 3 indicates an allowable safety strength MI of ultrasonic vibration MI = 0.25 and a temperature increase allowable limit value TI = 2.0 of the living tissue.
[0057]
As is apparent from this graph, if the output of the ultrasonic wave is constant (0.72 W / cm ² or 0.5 W / cm ^2,), a mechanical index MI is a strength index of the ultrasonic vibration as the frequency becomes higher It can be seen that the thermal index TI, which is lower and the temperature difference index indicating the influence of the temperature on the living tissue, increases as the frequency increases.
[0058]
The "safety margin" available frequency range in consideration of, if the ultrasonic output 0.72 W / cm ² become a range of 390KHz～580kHz, if the ultrasonic output 0.5 W / cm ² of 270kHz~840kHz It turns out that it is a range. Therefore, in consideration of the fluctuation range of the ultrasonic output, the usable frequency range is 250 kHz to 850 kHz.
[0059]
Next, experimental results of the transcranial ultrasonic therapy apparatus having the above-described configuration will be described.
First, the ultrasonic irradiation conditions are set by the control device 13 as follows.
[0060]
The ultrasonic output is set to 0.83 W / cm ² , the oscillation frequency is set to 490 kHz, and the supply period T1 is 2 minutes, the supply stop period T2 is 30 seconds, and the number n of sub-cycles is 4 as the intermittent irradiation time of the ultrasonic wave. The rest period T3 was set to 5 minutes, and thereafter, the rest period was 10 minutes. The ultrasonic probe used had an irradiation surface with a diameter of 5 mm, and a rat was used as an experimental model.
[0061]
FIG. 4 is a diagram showing the experimental results of the relationship between the intermittent irradiation time of the ultrasonic wave and the intracranial temperature and the rectal temperature. After four repetitions, a 15-minute cycle in which the dormant period was suspended for 5 minutes to make one cycle was repeated four times, followed by a 10-minute pause.
[0062]
In FIG. 4 (a), line A shows the intracranial temperature and line B shows the change in rectal temperature. FIG. 4 (b) shows the change from the initial temperature before the start of the experiment. Line A shows the intracranial temperature, and line B shows the change in rectal temperature. FIG. 4C shows the difference between the intracranial temperature and the rectal temperature.
[0063]
As is clear from FIGS. 4A to 4C, the temperature rise inside the living tissue could be suppressed to 2 ° C. or less by performing the intermittent irradiation of the ultrasonic waves.
[0064]
FIG. 5 is a diagram showing an experimental result showing a ratio between an intermittent irradiation time and a blood flow rate due to re-opening of a blood vessel when intermittent irradiation of ultrasonic waves is performed after artificially forming a thrombus in the experimental model. The horizontal axis indicates the intermittent irradiation time, and the vertical axis indicates the recirculation blood flow rate (the ratio of the recirculation blood flow to the blood flow before thrombus formation). In the figure, line A shows the case where the thrombolytic agent was used together with the intermittent irradiation of ultrasonic waves, and line B shows the case where only the thrombolytic agent was used without irradiating the ultrasonic waves for comparative reference.
[0065]
As is clear from FIG. 5, when the intermittent irradiation of the ultrasonic wave is started, the blood flow rate recovers to about 10% in 5 to 10 minutes. After that, the recovery of blood flow was large continuously and the effectiveness of ultrasonic irradiation was confirmed. On the other hand, when only the thrombolytic agent is used, the blood flow is recovered to about 10%, but thereafter, the blood flow is not recovered.
[0066]
FIG. 6 shows the recirculation blood flow rate when only a thrombolytic agent (TPA) is used after artificially forming a thrombus in the experimental model, and the intermittent ultrasonic irradiation (TU) of the thrombolytic agent (TPA). It is a figure which shows the resumption blood flow rate at the time of using together. The reperfusion blood flow rate is only about 10% when thrombolytic agent (TPA) is used alone, but when combined with intermittent ultrasonic irradiation (TU), the reperfusion blood flow rate increases to about 45%. The effectiveness of ultrasonic irradiation was confirmed.
[0067]
FIG. 7 shows the vascular patency rate (the ratio of keeping blood vessels open) when only a thrombolytic agent (TPA) is used after artificially forming a thrombus in the experimental model, and the thrombolytic agent (TPA). FIG. 7 is a diagram showing a vascular patency rate when intermittent irradiation (TU) of ultrasonic waves is used together. Two cases out of 12 cases using only thrombolytic agent (TPA), but 7 cases out of 9 cases when combined with intermittent irradiation of ultrasound (TU), it is extremely difficult to increase the vascular patency rate. The effectiveness of sonication was confirmed.
[0068]
【The invention's effect】
As described above in detail, according to the present invention, when irradiating an ultrasonic wave to a living tissue, the higher the vibration frequency of the ultrasonic wave, the larger the temperature rise of the living tissue, and the lower the vibration frequency of the ultrasonic wave, the more the cells are damaged By overcoming the contradictory condition of increasing the possibility that the ultrasonic vibration is likely to occur, the ultrasonic vibration frequency was determined within a range that could prevent the temperature rise and cell destruction of the living tissue while maintaining sufficient output intensity.
[0069]
Further, a cooling device that intermittently irradiates ultrasonic waves and cools the ultrasonic probe is combined to maintain the temperature rise of the living tissue within a safe range.
[0070]
As a result, a new transcranial ultrasound treatment apparatus for the head that can dissolve thrombus in the cerebral artery by irradiating ultrasound from outside the head can be provided.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram illustrating a basic configuration of a transcranial ultrasound therapy apparatus.
FIG. 2 is a block diagram illustrating a circuit configuration of a control device.
FIG. 3 is a diagram showing a relationship among the intensity, frequency, mechanical index MI, and thermal index TI of an ultrasonic wave.
FIG. 4 is a diagram showing a relationship between an intermittent irradiation time of an ultrasonic wave, an intracranial temperature, and a rectal temperature.
FIG. 5 is a diagram showing a ratio between an intermittent irradiation time of an ultrasonic wave and a blood flow rate due to reopening of a blood vessel.
FIG. 6 is a graph showing a recirculation blood flow rate when only a thrombolytic agent is used and a recirculation blood flow rate when intermittent ultrasonic irradiation is used in combination with the thrombolytic agent.
FIG. 7 is a diagram showing a vascular patency rate when only a thrombolytic agent is used and a vascular patency rate when intermittent irradiation of ultrasonic waves is used in combination with the thrombolytic agent.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Transcranial ultrasonic treatment apparatus 11 Ultrasonic probe 12 High frequency oscillator 13 Control device 14 Temperature sensor 15 Cooling device 21 Control unit 21a Oscillation frequency setting unit 21b Output intensity setting unit 21c Driving time setting unit 21d Temperature control unit 21e Operation panel 22 Amplifier 23 switching circuit 31 monitoring ultrasonic probe 32 ultrasonic monitoring device

Claims (8)

A transcranial ultrasound therapy device that transmits ultrasound through the skull and dissolves emboli of intracranial cerebral blood vessels,
An oscillator for generating a high-frequency current of 250 kHz to 850 kHz;
An ultrasonic probe that excites a vibrator based on a high-frequency current from the oscillator and projects ultrasonic waves having a frequency of 250 kHz to 850 kHz;
Drive control means for intermittently supplying a high-frequency current output from the oscillator to the ultrasonic probe,
A transcranial ultrasonic therapy apparatus, comprising: a cooling unit configured to cool a surface temperature of an ultrasonic irradiation unit of the ultrasonic probe to a predetermined temperature range. The transcranial ultrasonic treatment apparatus according to claim 1, wherein the ultrasonic probe is an ultrasonic probe that projects a non-convergent ultrasonic beam that does not converge on a specific site. The drive control means controls the high-frequency current output from the oscillator by an intermittent cycle in which a sub-cycle consisting of a supply period T1 and a supply stop period T2 is repeated n times and then paused for a pause period T3 to make one cycle. 2. The transcranial ultrasonic therapy apparatus according to claim 1, wherein said ultrasonic probe is drive control means for supplying said ultrasonic probe to said ultrasonic probe. 4. The high-frequency current supply period T1 in the drive control means is 2 minutes, the supply suspension period T2 is 30 seconds, the number n of sub-cycle repetitions is four, and the suspension period T3 is 5 minutes. Transcranial ultrasound therapy device. 2. The cooling unit according to claim 1, wherein the cooling unit is controlled to maintain a surface temperature of an ultrasonic irradiation unit of the ultrasonic probe within a temperature range higher by 2 ° C. than a standard body temperature. Transcranial ultrasound therapy device. The transcranial ultrasonic therapy apparatus according to claim 5, wherein the cooling unit is a cooling unit that circulates a cooling liquid inside the ultrasonic probe to cool the ultrasonic probe. 6. The transcranial ultrasonic therapy apparatus according to claim 5, wherein the cooling unit is a cooling unit that energizes and cools the Peltier effect element disposed inside the ultrasonic probe. The transcranial ultrasonic treatment apparatus according to claim 1, wherein the transcranial ultrasonic treatment apparatus includes an ultrasonic probe support device that presses the ultrasonic probe to a head and adheres the ultrasonic probe to the head.

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