JPH0678930A - Ultrasonic therapy apparatus - Google Patents

Abstract

PURPOSE:To improve the radiation therapy efficiency and safety by installing a plurality of piezoelectric elements for radiaing ultrasonic waves on a subject to be irradiated at a desired focus position of an inspected body and allowing a plurality of piezoelectric elements to be driven at a prescribed equal delay time difference for one or a plurality of elements. CONSTITUTION:An annular piezoelectric element group 21-26 is arranged in a spherical shell form, and an applicator 1 is constituted by arranging an ultrasonic probe 3 for imaging at the center of the piezoelectric element group 21-26, and the applicator 1 is applied to an inspected body 4 through a water bag 6, in order to radiate ultrasonic waves on the concretion 5 in an inspected body 4 for pulverization treatment. Each of the piezoelectric group element 21-26 is driven with a prescribed delay time difference set by a delaying circuit 10, by the pulse generated from pulsers 71-76 by the signal of a trigger control circuit 11. The delay time difference is determined by referring the pulverization degree information for the concretion which is taken out from a pulverization degree measuring circuit 11 and the delay time difference information corresponding to the pulverization degree in a memory 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic therapeutic apparatus for irradiating a subject with ultrasonic waves for treatment, and more particularly to an ultrasonic therapeutic apparatus using a piezoelectric element as an ultrasonic source.

[0002]

2. Description of the Related Art In recent years, as a method for removing stones in the body without surgery, a method of focusing strong ultrasonic waves (shock waves) from the outside on the stone site in the body to crush the stones has been proposed and widely used. Has become. Similarly, a method for treating a tumor in the body by focusing ultrasonic waves from the outside of the body is being studied.

As described above, ultrasonic waves are widely applied in the medical field, but since the focus size of ultrasonic waves is fixed, it is not possible to irradiate ultrasonic waves corresponding to the size of the affected area. As a result, the focal size of the ultrasonic waves to be applied to a wide range of affected areas is too small and the irradiation treatment efficiency is poor, and conversely the focal size of the ultrasonic waves to be applied to a narrowed affected area is too large. Therefore, there is a defect that even normal tissue around the affected area is damaged.

Therefore, in the case of weak ultrasonic waves for diagnosis, by changing the driving time of the piezoelectric element group which is an ultrasonic wave generating element, the focused state of the ultrasonic waves emitted is changed, or Separately, a method is known in which only a desired inner piezoelectric element group is driven or every other concentrically arranged piezoelectric elements are driven to enlarge the focus size (Japanese Patent Laid-Open No. 1-37638). reference).

However, a method for increasing the focus size of the above-mentioned conventional ultrasonic source, that is,
The method of enlarging the focal size of ultrasonic waves by making the driving time different has a problem that the focal position moves back and forth. Further, in the method of selectively using the piezoelectric element group, there is a problem that there is a piezoelectric element group that is not driven and the focus energy is substantially reduced. In particular, in the method of selectively using this piezoelectric element group, for example, if the number of piezoelectric elements driven for focus expansion is ½ of the total number of piezoelectric elements, the focus energy is maintained even during focus expansion. For this purpose, the energy input to each piezoelectric element may be doubled when the focus is not enlarged.
In the case of weak ultrasonic waves for diagnosis, since there is a margin in the pressure resistance of the piezoelectric element, increasing the input energy can solve the problem of the decrease in focal energy at the time of expanding the focal point, but the ultrasonic wave for calculus breaking used for treatment In the case of sound waves, there is a problem that when the energy is further applied to the piezoelectric element, the withstand voltage of the piezoelectric element is exceeded and the piezoelectric element itself is destroyed.

[0006]

As described above,
The method of enlarging the focal size of ultrasonic waves by making the driving time different has a problem that the focal position moves back and forth. Further, in the method of selectively using the piezoelectric element group, there is a problem that there is a piezoelectric element group that is not driven and the focus energy is substantially reduced. In particular, in the method of selectively using this piezoelectric element group, in the case of weak ultrasonic waves for diagnosis, since there is a margin in the withstand voltage of the piezoelectric element, the input energy is increased to reduce the focus energy during focus expansion. However, in the case of ultrasonic waves for calculus breaking used for treatment, there is a problem that the piezoelectric element itself is destroyed due to exceeding the withstand voltage of the piezoelectric element.

The present invention eliminates the above-mentioned conventional drawbacks, and even if a conventional piezoelectric element is used, the focus size can be set to a desired size without reducing the focus energy while setting the focus position to a desired position. It is an object to provide an ultrasonic therapy device that can be set.

[0008]

In order to achieve the above-mentioned object, the present invention adjusts the phase of a power pulse applied to a piezoelectric element group in an ultrasonic treatment apparatus using a plurality of piezoelectric elements as an ultrasonic wave generation source. Then, increase the focus size.

More specifically, a plurality of piezoelectric elements capable of irradiating an object to be irradiated with ultrasonic waves at a desired focal position of the object, and drive control means for controlling the driving of each of these piezoelectric elements with a predetermined delay time difference. An ultrasonic therapy device is constructed from the above.

The wavelength λ of the ultrasonic wave and the propagation velocity v
Then, the delay time difference t is set to satisfy 0 <t <0.5λ / v.

Further, a plurality of piezoelectric elements capable of irradiating an object to be irradiated with ultrasonic waves at a desired focus position of the object, drive control means for controlling the driving of each of these piezoelectric elements with a predetermined delay time difference, and the piezoelectric element. Based on the crushing degree measuring means for measuring the crushing degree of the irradiated object crushed by the ultrasonic waves emitted from the group, and the crushing degree measured by this crushing degree measuring means and preset crushing degree information. The delay time difference is calculated.

[0012]

When the piezoelectric element groups arranged concentrically are numbered in order from the inner circumference side, there is no delay time for the odd-numbered annular piezoelectric element groups and the even-numbered annular piezoelectric element groups. The drive is performed with a predetermined delay time difference. More preferably, the delay time difference is determined within the duration of the positive half-wave of the ultrasonic wave at the focus position. That is, when the wavelength λ of the ultrasonic wave and the propagation velocity v are set, the desired delay time difference t is set to be t <0.5λ / v.

Therefore, according to the present invention, when the ultrasonic wave radiated from the piezoelectric element group driven with no delay time difference reaches the focal position, the piezoelectric element group driven with the delay time difference in the above range t. Since the ultrasonic waves emitted from the ultrasonic wave reach within a distance of a half wavelength from the focal position, the focal size is enlarged without reducing the energy at the focal position.

Furthermore, by combining with a means capable of determining the size of the irradiated object, an optimum focus size can be obtained in response to changes in the size of the irradiated object during treatment. If it is small, reduce the focus size to reduce side effects by limiting the irradiation around the irradiation target.If the irradiation target is large, increase the focus size to efficiently target the irradiation target. Irradiation becomes possible, and irradiation efficiency and safety can be improved.

[0015]

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

FIG. 1 is a diagram showing the configuration of an ultrasonic therapeutic apparatus according to the present invention. In the figure, the applicator 1 is
The ring-shaped piezoelectric element groups 21 to 26 are arranged in a spherical shell shape, and the ultrasonic probe 3 for imaging is inserted and arranged at the center of the piezoelectric element groups 21 to 26. This applicator 1 is brought into contact with the subject 4 via a flexible water bag 6 in order to irradiate ultrasonic waves on the calculi 5 in the subject 4 and treat them for crushing.

The piezoelectric element groups 21 to 26 are connected to the pulsers 71 to 76, respectively, and can be independently driven. The pulsars 71 to 76 are connected to the power source 8 which is a driving source, and drive the piezoelectric element groups 21 to 26 based on the signal of the trigger control circuit 11 via the delay circuit 10 controlled by the control unit 9. Generate power pulses. The delay circuit 10 gives a delay time difference to the pulsers 71 to 76 by the control signal from the control unit 9. The crushing degree measuring circuit 12 monitors the progress of the calculus crushing treatment, measures the size of the calculus before the treatment and the size of the calculus fragment during the treatment, and the crushing degree information to the control unit 9. Output. The control unit 9 determines the delay time difference by referring to the crushing degree information of the calculus acquired from the crushing degree measuring circuit 11 and the delay time difference information corresponding to the crushing degree of the calculus preset in the memory 13. The delay time difference information is output to the delay circuit 10. The delay time difference information may be appropriately input by the user from the keyboard 14.

As described above, the delay time difference can be arbitrarily set according to the progress of calculus crushing, and efficient crushing treatment can be realized.

FIG. 2 is a diagram showing a pulse sequence of the pulser of the ultrasonic therapeutic apparatus according to the present invention. The trigger signal T obtained from the trigger controller is generated by an irradiation command from the user or at a predetermined cycle. Preferably, when the focus position of the applicator 1 and the calculus 5 match, the trigger signal T
Is desirable. When the trigger control circuit 11 outputs the trigger signal T to the delay circuit 10, the delay circuit 10
The trigger signal T is output to the pulsars 71, 73, 75 with no delay time difference, and based on this, the pulsars 71, 73,
75 outputs the pulse P1 to the piezoelectric element groups 21, 23 and 25. On the other hand, a trigger signal T is output to the pulsars 72, 74 and 76 with a delay time difference D within a half wavelength 1 / 2λ of an ultrasonic wave, which will be described later, and based on this, the pulsars 72, 74 and 7 are output.
6 outputs the pulse P2 to the piezoelectric element groups 22, 24 and 26. These piezoelectric element groups 21, 23, 25 and 22, 2
The ultrasonic waves W1 and W2 generated from Nos.
After that, the calculus 5, which is the focus position, is reached. At this time, the combination of the ultrasonic waves W1 and W2 is observed as shown by W due to the nonlinearity of the ultrasonic waves. With this, by setting the delay time difference to a predetermined value, without changing the focal position,
It is possible to enlarge the focus size with less reduction in focus energy.

Here, the delay time difference D is determined so as to satisfy 0 <D <0.5λ / v, where ultrasonic wavelength is λ and propagation velocity is v. For example, frequency 500 [k
Hz] ultrasonic wave delay time difference D = 0.7 [μs]
Then, it has been confirmed by experiments that the focal size in water can be increased by 1.5 times. Table 1 shows frequency 50
The relationship between the delay time difference D and the focus size S in an ultrasonic wave of 0 [kHz] is shown as follows:
= 1.

[0021]

[Table 1] FIG. 3 is a diagram showing a pulse sequence of a pulser when the phased array principle is used. In the present embodiment, the focus position of the applicator 1 can be moved back and forth on its central axis, and at the same time, the focus size can be expanded at the moving focus position. That is, when it is desired to set the focus position axially before the geometrical focus position of the applicator, as shown in FIG.
By taking the delay time difference D so that the waveforms shown by the solid lines are obtained for the outputs of 4,76, the focus position can be formed axially before the focus position determined by the geometric position, and the focus size can be enlarged. . Similarly, as shown in FIG. 3B, if the delay time difference is set, the focus position can be located farther than the geometric focus position and the focus size can be expanded. If the delay time difference in this case is input to the memory as data and is called according to a desired value, the focus size can be enlarged at the desired focus position without lowering the irradiation efficiency.

In the present embodiment, the delay time difference is given to the even-numbered piezoelectric elements from the inner circumference side, but the delay time difference may be given to the odd-numbered piezoelectric elements. Further, in each case, six annular piezoelectric element groups are used, but the present invention is not limited to this.

FIG. 4 shows another embodiment of the present invention. In FIG. 4A, a piezoelectric element group for ultrasonic wave generation is radially divided into a plurality of groups, and the piezoelectric element groups 21, 23, 25 and 27 shown by hatching in the figure are driven with a predetermined delay time difference, If the piezoelectric element groups 22, 24, 26, and 28 are driven with no delay time difference, as in the above-described embodiment, the focus position is not changed as compared with the case where the focus is not enlarged, and the focus energy is not reduced. An increase in focal spot size is achieved. Again, it is preferable to set the delay time difference within the positive duration of the pressure pulse at the focus.

Further, FIG. 4 (b) shows a combination of piezoelectric element groups in a lattice form, which is driven by giving a delay time difference to the piezoelectric element groups indicated by hatching in the figure and driving the other piezoelectric element groups. Drive with no delay time difference. Also in this case, enlargement of the focus size without reduction of the focus energy is achieved without changing the focus position as compared with the case where the focus is not enlarged.

In each of the above-described embodiments, the driving of the pulsar is controlled by using the delay circuit 10. However, as shown in FIG. 5, the trigger control circuits 111 to 116 are provided corresponding to the pulsars 71 to 76, respectively. It may be provided. in this case,
Although the control unit 9 directly controls the operations of the trigger control circuits 111 to 116, the focus size can be increased as in the above-described embodiment.

[0026]

According to the present invention, when the ultrasonic wave radiated from the piezoelectric element group driven with no delay time difference reaches the focal position, the piezoelectric element group driven with the delay time difference in the range of t described above. Since the ultrasonic wave emitted from the ultrasonic wave reaches within a half wavelength distance from the focal position, the focal size of the ultrasonic wave can be expanded without changing the focal position and reducing the energy at the focal point. .

Furthermore, by combining with a means capable of determining the size of the irradiation target, the optimum focus size can be instantaneously determined and applied in response to changes in the size of the irradiation target during treatment. It is possible to improve efficiency and safety. That is, when the irradiation purpose is small, the focus size is reduced, and thus side effects are reduced by limiting the irradiation around the irradiation purpose, and when the irradiation purpose is large, the focus size is increased to increase the irradiation purpose. It becomes possible to irradiate efficiently.

Therefore, it is possible to improve the efficiency of irradiation treatment and reduce side effects.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an ultrasonic therapeutic apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a pulse sequence of a pulser of the ultrasonic therapy apparatus in FIG.

FIG. 3 is a diagram showing a pulse sequence of a pulser when the principle of phased array is used.

FIG. 4 is a view for explaining the arrangement of piezoelectric element groups according to another embodiment of the present invention.

FIG. 5 is a diagram for explaining driving of a pulser according to another embodiment of the present invention.

[Explanation of symbols]

1 ... Applicator 3 ... Imaging probe 4 ...
Subject, 5 ... Stones 6 ... Water bag 8 ... Power section 9 ... Control section 10 ... Delay circuit
11 ... Trigger control circuit 12 ... Fracture degree measurement circuit 13 ... Memory 14 ... Keyboard 71-76 ... Pulsar

Claims (3)

[Claims] 1. A plurality of piezoelectric elements for irradiating an object to be irradiated with ultrasonic waves at a desired focus position of a subject, and a drive for separately controlling the driving of one of these piezoelectric elements and another piezoelectric element. An ultrasonic therapy apparatus having a control means,
The ultrasonic treatment device according to claim 1, wherein each of the plurality of piezoelectric elements is driven with a predetermined same delay time difference. 2. A plurality of piezoelectric elements for irradiating an object to be irradiated with ultrasonic waves at a desired focus position of a subject, drive control means for controlling the driving of each of these piezoelectric elements with a predetermined delay time difference, and the plurality of piezoelectric elements. The crushing degree measuring means for measuring the crushing degree of the irradiated object crushed by the ultrasonic waves emitted from the element, and the crushing degree measured by the crushing degree measuring means and preset crushing degree information based on the above. An ultrasonic therapy device, comprising: means for calculating a delay time difference. 3. The ultrasonic wave according to claim 1, wherein the delay time difference t satisfies 0 <t <0.5λ / v, where λ is the wavelength of the ultrasonic wave and v is the propagation velocity. Treatment device.