JPH10216143A - Ultrasonic irradiator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic irradiator which enables reducing of errors in a spatial relative relationship of intensity in vivo of an ultrasonic wave for treatment. SOLUTION: A group 2 of piezo-electric elements is provided to irradiate a subject 6 with an ultrasonic wave for treatment and an ultrasonic probe 3 for imaging is provided to transmit an ultrasonic wave for imaging into the subject 6 while receiving a reflected wave from the subject 6. A comparator means 13 is provided to compare a first received signal pertaining to a reflected wave of the ultrasonic wave for treatment received by the ultrasonic probe 3 for imaging and a second received signal pertaining to a reflected wave of the ultrasonic wave for imaging received by the ultrasonic probe 3 for imaging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an ultrasonic heating device,
The present invention relates to an ultrasonic irradiation device such as an ultrasonic ablation device and an ultrasonic calculus crushing device.

[0002]

2. Description of the Related Art In recent years, extracorporeal shock wave calculus pulverization has been developed in which a powerful ultrasonic pulse is focused on a calculus to perform crushing treatment, and has become the first choice for calculus treatment in the urological field. Recently, a hyperthermia technique for irradiating tumor cells with ultrasonic waves for treatment, and a treatment technique for focusing high-intensity ultrasound waves on tumor cells and heating them to a high temperature to cause thermal degenerative necrosis have been developed and are in the spotlight. These techniques are expected to be less invasive to patients as compared to surgical operations.

However, erroneous irradiation of normal tissue with intense ultrasonic waves for treatment may cause side effects such as damage to normal tissue. In order to solve this, for example, in a calculus crushing device, before irradiating a strong ultrasonic pulse for calculus crushing, a weak ultrasonic pulse to irradiate a strong ultrasonic pulse in advance to confirm whether the focal point and the calculus coincide with each other is applied in advance. Then, a method of irradiating a high-intensity ultrasonic pulse for treatment after confirming the presence or absence of a calculus has been proposed (Japanese Patent Application Laid-Open No.
No. 5736).

[0004] In addition, regarding heat treatment of tumor cells by high-intensity ultrasonic waves, in order to monitor the target and high-intensity ultrasonic waves for treatment, the cell temperature in a region coincident with the focal point is increased by several degrees. A method has been proposed in which a position is confirmed by irradiating a sound wave with a magnetic resonance diagnostic apparatus (MRI) and then intense ultrasonic waves for treatment are used (Japanese Patent Application No. 5-228744).

Further, a method of acquiring a reflected signal of an ultrasonic wave irradiated from a therapeutic ultrasonic source in a living body with an ultrasonic probe for imaging and imaging the same (Japanese Patent Application Laid-Open No. Sho 60-1451).
No. 31), a method of detecting a harmonic signal generated at a focused portion of a high-intensity therapeutic ultrasonic wave and displaying a focal region on an ultrasonic image device (Japanese Patent No. 1851304), and a method of detecting a subject from a therapeutic ultrasonic source Method of analyzing the frequency information of the reflected ultrasonic wave from the subject of the ultrasonic pulse irradiated toward the inside to obtain the distribution state of the nuclear ultrasonic pulse (Japanese Patent Application No. 8-70206)
No.) has been proposed.

[0006]

The focus image or the intensity distribution image of the therapeutic ultrasonic wave, which is imaged by the above-described method, shows the reception intensity of the therapeutic ultrasonic wave as an absorptance or a reflection at each point in the subject. Since the reflectance is multiplied, if there is a large fluctuation in the reflectance or the like in the subject, an image different from the actual intensity distribution, specifically, does not represent the absolute value of the intensity. They displayed very low-level images, even if the spatial relationships were incorrect.

[0007] Further, since the existence of a shield or a strong absorber in the propagation path of the therapeutic ultrasonic wave to the focal point is unknown, a reduction rate of the therapeutic ultrasonic wave due to these influences cannot be obtained.

[0008] It is an object of the present invention to provide an ultrasonic irradiation apparatus capable of reducing errors in the spatial relative relationship between the in-vivo intensities of therapeutic ultrasonic waves.

Another object of the present invention is to provide an ultrasonic wave capable of obtaining a reduction rate of a therapeutic ultrasonic wave due to the presence of an unknown shield or a strong absorber in a propagation path to the focal point of the therapeutic ultrasonic wave. An irradiation device is provided.

[0010]

According to the present invention, there is provided an ultrasonic irradiation apparatus comprising: an ultrasonic irradiation unit for irradiating a therapeutic ultrasonic wave into a subject; transmitting an imaging ultrasonic wave into the subject; An imaging ultrasonic probe that receives a reflected wave from a subject, a first reception signal related to a reflected wave of the therapeutic ultrasonic wave received by the imaging ultrasonic probe, and the first signal received by the imaging ultrasonic probe. Second related to reflected wave of ultrasonic wave for imaging
Means for comparing with a received signal.

[0011] The comparing means is configured to determine the intensity of the first received signal and the second received signal based on a first intensity ratio and a frequency ratio of the second received signal and an absorption coefficient in the object. The second of the therapeutic ultrasound and the imaging ultrasound
Means for calculating the intensity ratio is provided.

[0012] The comparing means may include a second intensity ratio obtained in an environment where there is no obstruction and an actual second intensity ratio obtained from the subject. Means for estimating a rate of decrease of the therapeutic ultrasonic wave between a point and the ultrasonic probe for imaging.

[0013] The comparing means may include an intensity ratio between the first received signal and the second received signal, and an attenuation received by the imaging ultrasonic wave from a point in the subject to the imaging ultrasonic probe. Means for estimating a spatial relative value of the intensity of the therapeutic ultrasonic wave at a point in the subject based on the rate and the transmission intensity of the imaging ultrasonic wave.

The comparing means has means for estimating the attenuation rate based on a function of a gain curve for correcting the depth dependency of the attenuation.

[0015] The comparing means may include an intensity ratio between the first received signal and the second received signal, a depth of a point in the subject, and a transmission frequency of the therapeutic ultrasonic wave and the imaging ultrasonic wave. Estimating the absolute value of the intensity of the therapeutic ultrasound at a point in the subject based on the ratio, the absorption coefficient of the imaging ultrasound in the subject, and the transmission intensity of the imaging ultrasound. Have means to do so.

2. An ultrasonic irradiation apparatus according to claim 1, wherein said comparing means has means for comparing the intensity ratio between said first received signal and said second received signal with a predetermined value over time.

Further, the ultrasonic irradiation apparatus according to the present invention comprises: an ultrasonic irradiation means for irradiating a therapeutic ultrasonic wave into a subject; transmitting an imaging ultrasonic wave into the subject;
An ultrasound probe for imaging that receives a reflected wave from inside the subject, a unit that reconstructs an ultrasound image in the subject based on an output from the ultrasound probe for imaging, and the ultrasound irradiation unit. Means for controlling the operation timing of the imaging ultrasonic probe, a first reception signal related to a reflected wave of the therapeutic ultrasonic wave received by the imaging ultrasonic probe, and the imaging received by the imaging ultrasonic probe. Means for comparing a second received signal related to the reflected wave of the ultrasonic wave for use, means for analyzing frequency information of the first received signal,
Means for displaying the frequency information and the comparison result.

Further, the ultrasonic irradiation apparatus according to the present invention comprises: an ultrasonic irradiation means for irradiating a therapeutic ultrasonic wave into a subject; transmitting an imaging ultrasonic wave into the subject;
An imaging ultrasonic probe that receives a reflected wave from the subject; a first reception signal related to a reflected wave of the therapeutic ultrasonic wave received by the imaging ultrasonic probe; and a first reception signal that is received by the imaging ultrasonic probe. Means for amplifying the second received signal related to the reflected wave of the imaging ultrasonic wave, and means for controlling the gain for the first received signal in conjunction with the gain for the second received signal.

According to the present invention, the first related to the reflected wave of the therapeutic ultrasonic wave received by the imaging ultrasonic probe.
Using the comparison result between the received signal and the second received signal related to the reflected wave of the imaging ultrasonic wave received by the imaging ultrasonic probe, the error in the spatial relative relationship of the in-vivo intensity of the therapeutic ultrasonic wave is reduced. obtain.

Also, based on the comparison result, it is possible to obtain the rate of decrease of the therapeutic ultrasonic wave due to the influence of the unknown shield or strong absorber in the propagation path to the focal point of the therapeutic ultrasonic wave. Therefore, it is possible to appropriately adjust the intensity of the therapeutic ultrasonic wave to obtain a reliable and highly accurate therapeutic effect.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A night ultrasonic irradiation apparatus according to the present invention will be described with reference to the drawings. (First Embodiment) FIG. 1 shows a first embodiment in which the present invention is applied to a tumor treatment apparatus using intense ultrasound. In the figure, the therapeutic ultrasonic applicator 1
A piezoelectric element group 2 arranged on a spherical surface such that the wavefront of the generated ultrasonic wave is concave, an ultrasonic imaging probe 3 inserted and arranged at the center of the piezoelectric element group 2, and a flexible water bag 4 It is constituted by. In the water bag 4, an ultrasonic wave propagation medium, for example, well-degasified water 5 is sealed.

Here, the imaging ultrasonic probe 3
Can be used in either a mechanical scan type or an electronic scan type, but in the present embodiment, description will be made on the assumption that an electronic scan type sector probe is used.

The applicator 1 is brought into contact with the patient 6 via the water bag 4, and the treatment element 7 is irradiated with ultrasonic waves for treatment from the piezoelectric element group 2. The imaging ultrasonic probe 3 is connected to an ultrasonic imaging device 8. The piezoelectric element group 2 is connected to an amplifying means 10 for amplifying for driving, and the amplifying means 10 amplifies the driving waveform from the waveform generating means 11 to electric power required for driving.

In this embodiment, there are three modes: an imaging mode (a), a focus intensity index acquisition mode (b), and a treatment mode (c). The operator specifies the operation mode of the apparatus by the input means 9. Each operation mode may be designated independently, or mode (b) to mode (c)
It is also possible to specify to automatically transition to.

For example, when the focus intensity index acquisition mode (b) is selected, the control unit 12 controls the waveform generation unit 11
The output of the amplifying means 10 is reduced in order to control the number of bursts of ultrasonic waves generated in the above step to, for example, about 1 to 3 waves, and to obtain ultrasonic energy which does not affect the living body. On the other hand, when the treatment mode (c) is selected, the number of bursts and the output of the ultrasonic wave radiated from the piezoelectric element group 2 are increased to a size necessary for the treatment.

Here, it is assumed that the operation mode is set to automatically shift from the mode (b) to the mode (c).
In the mode (b), the effect of the ultrasonic shield or the strong absorber existing in the propagation path (the reduction rate to the focal point due to these) is estimated.

The reflected wave from the vicinity of the treatment target 7 is received by the imaging ultrasound probe 3 and the ultrasound imaging device 8 and its acoustic intensity or amplitude is stored in a memory (not shown) in the comparison means 13. This operation is performed by the piezoelectric element group 2
This is performed for each of the therapeutic ultrasonic pulse radiated from the imaging ultrasonic pulse and the imaging ultrasonic pulse radiated from the imaging ultrasonic probe 3.

At this time, it is preferable to perform this operation when the direction of the imaging ultrasonic beam is on the axis of the imaging ultrasonic probe 3 because post-processing is simplified. The acoustic intensity or amplitude to be recorded may be based on a reflected wave from a geometrical focal position determined by the shape of the piezoelectric element group 2 or may be selected from those near the position with the highest intensity. good. Alternatively, an average of the reflected wave intensities from these nearby positions may be used. Next, as shown by the expressions (1) and (2) described later, the two recorded values of the ultrasonic intensity or amplitude (the treatment radiated from the piezoelectric element group 2 and received by the ultrasonic probe for imaging 3). Ratio of a first received signal related to the reflected wave of the imaging ultrasonic wave to a second received signal related to the reflected wave of the imaging ultrasonic wave transmitted from the imaging ultrasonic probe 3 and received by the imaging ultrasonic probe 3; The ultrasound intensity ratio at the site of interest (focal region) is calculated by multiplying by a predetermined coefficient.

Next, the effect of absorption attenuation is corrected. The result is displayed on the display unit 14 or the ultrasonic imaging device 8.
Is displayed on a CRT (not shown). Here, a calculation formula for the above estimation will be described. Both received signals are generally signals of different frequencies, and their effects are reflected on the reflection coefficient T and the absorption coefficient α of the ultrasonic wave. It is known that the reflection of ultrasonic waves in soft tissue is usually based on Rayleigh scattering, in which case the reflection coefficient T is proportional to the fourth power of the frequency f.

On the other hand, the absorption coefficient α is proportional to the frequency, and the intensity of the ultrasonic wave when propagated by the distance x is given by multiplying the original value by e- ^2αx .

As described above, the intensity of the ultrasonic wave at the site of interest is Ii (the intensity of the second received signal) and It (the intensity of the first received signal), and the reflected ultrasonic waves from the region of interest reach the ultrasonic probe 3 for imaging. The ultrasonic intensity at the time of Ri and R
t and the ratio between the two (the subscript i represents the ultrasonic wave radiated from the imaging ultrasonic probe 3 and the subscript t represents the ultrasonic wave radiated from the piezoelectric element group 2), the reflectance and the attenuation rate Cancel unknowns (due to shielding, absorption, etc.)

(Equation 1)

The absorption coefficient α is proportional to the frequency f,

(Equation 2)

## EQU1 ## However, for simplicity, the piezoelectric element group 1
The propagation distance in the patient 6 of the ultrasonic wave radiated from the body and the ultrasonic wave radiated from the imaging ultrasonic probe 3 is assumed to be equal. In addition, since the imaging ultrasonic pulse and the ultrasonic pulse emitted from the piezoelectric element group 2 are pulse waves, energy is distributed in a frequency band extending from a center frequency to a certain region. Here, for simplicity,
Fi and ft where the energy density spectrum of each received wave is the largest frequency were adopted.

For further simplification, the nominal center frequency of reception of the ultrasonic pulse for imaging and the resonance frequency of the piezoelectric element group 2 may be used. For αi, the absorption coefficient of the target tissue may be separately measured or obtained or a value introduced in literatures may be used, but the depth of the reflected ultrasonic wave from the living body of the ultrasonic pulse for imaging may be used. Can be obtained from the attenuation rate depending on

As described above, in the soft tissue, the ultrasonic intensity changes by e ^{- 2αx} times as the distance x propagates. Thus, α is obtained by taking the logarithm of the received signal strength and measuring the slope. Normally, when an ultrasonic image is displayed by a commercially available ultrasonic diagnostic apparatus, the logarithm of the ultrasonic intensity is made to correspond to the luminance of the image in accordance with the sensitivity of human eyes. Therefore, if the logarithmic output of the intensity of the received signal contained in the ultrasonic diagnostic apparatus is used, the measurement of α is easy. Of course, a circuit for logarithmically converting the intensity of the received RF signal may be added and the output thereof may be used.

In any case, the received signal may contain noise or a high-intensity signal due to a reflector in the middle may be mixed. Therefore, the least squares method or other statistical processing is used. It is preferable to obtain α with sufficient accuracy for practical use. Note that α can be measured similarly by using the ultrasonic waves emitted from the piezoelectric element group 2. From the above, Ii / It is back calculated to obtain the ultrasonic intensity ratio at the site of interest.

Here, the imaging ultrasonic probe 3 is arranged between the imaging ultrasonic probe 2 and the target region so that no ultrasonic shield or strong absorber exists between the imaging ultrasonic probe 2 and the target region. In general, for example, the ultrasonic probe for imaging 3 is approached from between the ribs. On the other hand, the piezoelectric element group 2 serving as a therapeutic ultrasonic source has a wider ultrasonic radiation surface than the ultrasonic probe 3 for imaging, and generates focused ultrasonic waves. For this reason, even when the ultrasonic shield or the strong absorber is not drawn on the ultrasonic tomographic image by the imaging ultrasonic waves, these may exist in the propagation path of the ultrasonic wave radiated from the piezoelectric element group 2. In this case, the intensity of the focused ultrasonic wave falls below the predetermined intensity.

Therefore, under known conditions, for example, an environment where there is no obstruction, specifically, Ii / It and absorption coefficient α (zero in water) measured in advance in water or in a phantom are stored in the memory. In the ultrasonic wave propagation path for treatment by storing the data in an ultrasonic transmission path, or by inputting the data through an input means 9 by an operator, and comparing the measured data with Ii / It measured in actual clinical practice. It is possible to know the rate of decrease in the intensity of the therapeutic ultrasonic waves from the piezoelectric element group 2 to the focal point due to the influence of the ultrasonic shield or the strong absorber existing in the above.

That is, when there is no shield or ultrasonic absorber, if the absorption coefficient α and the input ultrasonic power are determined, I
i / It is determined. However, when a shield or an absorber exists, the amount of decrease of It becomes larger than Ii, so that Ii / It changes.

The result is transferred to the control means 12 and displayed on the display means 14 or a CRT (not shown) in the ultrasonic imaging apparatus 8 to notify the operator. Next, the attenuation due to the ultrasonic absorption of the living body is calculated from the absorption coefficient αt and almost half of the propagation distance (that is, the distance from the ultrasonic probe to the focal point) or from the attenuation ratio of the received signal. The input energy (electrical energy applied to the piezoelectric element group 2) for surely causing the focal region to be denatured and necrotic is determined from the rate of reduction of the focus intensity due to shielding or absorption.

The operations performed by the comparison means 13 and the control means 12 described above are shown in the flowchart of FIG. After determining the electric energy to be applied to the piezoelectric element group 2 in this way, the result is transferred to the control means 12 and the display means 14 is displayed.
Alternatively, it is displayed on a CRT in the ultrasonic imaging apparatus 8. Then, the control unit 12 controls the outputs of the waveform generation unit 11 and the amplification unit 10 to obtain a desired ultrasonic burst. The above calculation results may be displayed only, and the output control of the waveform generation means 11 and the amplification means 10 may be controlled by the operator using the input means 9.

Further, as shown in FIG. 3, it is possible to confirm whether or not the therapeutic effect (denaturation by heat) has been surely obtained by comparing the above-mentioned temporal changes in Ri or Rt. . The heat-denatured area caused by the irradiation of the therapeutic ultrasonic burst has acoustic characteristics different from those of normal tissue, and the ultrasonic reflectance at the interface between the denatured area and normal tissue increases. In addition, the absorption coefficient of ultrasonic waves is larger than that of normal tissue. Therefore, as the heat denatured region is formed, the intensity of the reflected wave at the interface with the normal tissue increases, and the amount of ultrasonic absorption in the denatured region increases. From these, Ri and Rt in the denatured region
Changes before and after the irradiation of the therapeutic ultrasonic burst.

Here, by observing the change over time of Ri or Rt or a ratio thereof, whether or not a thermally denatured region was formed, and a means for measuring the attenuation coefficient to measure the size of the thermally denatured region are described. explain. First, Ri or Rt or a ratio thereof from the focal region is acquired before the irradiation of the therapeutic ultrasonic burst, and is stored in the recording device in the comparing means 13 (not shown) of FIG. Next, the control means 12 divides Ri or Rt or their ratio received over time by the imaging ultrasonic probe 3 by the recorded Ri or Rt or their ratio, respectively, and divides the result by a numerical value. Alternatively, the information is displayed on the display unit 14 or a CRT (not shown) in the ultrasonic imaging apparatus 8 by changing the luminance information or the color or the pattern. This operation may be performed continuously during or after the irradiation of the therapeutic ultrasonic burst.

For example, since Ri has a frequency different from that of the therapeutic ultrasonic burst, if only this frequency can be detected by a filter or the like, Ri can be obtained even during irradiation of the therapeutic ultrasonic burst. Therefore, when Ri becomes larger than the value input or recorded in advance, the irradiation of the therapeutic ultrasonic burst may be stopped, assuming that the degenerated area has been formed.

If the state of the change of Ri over time is displayed on an ultrasonic tomographic image, the progress of thermal denaturation can be confirmed (FIG. 3A). Even if Ri is not acquired during irradiation of the therapeutic ultrasonic burst, R
By obtaining i or Rt or their ratio and comparing it to the recorded pre-irradiation Ri or Rt, it may be determined whether additional irradiation is needed. If the center raster always crosses the focal area, Ri on the raster is acquired for each spatial position using a time gate or the like, and the amount of attenuation of the ultrasonic wave is determined from the intensity change. Can be approximated. For example, if the logarithm of the intensity of Ri is taken along this line, the slope becomes equal to the absorption coefficient α.

At this time, the inclination may be obtained by using a statistical method. This gradient is large in the thermally denatured region, and since the original absorption coefficient remains at the normal part before and after the region, and the reflection coefficient at the boundary surface increases as described above, A discontinuous point appears (FIG. 3B). The length during this period is the length of the denatured region. In the same manner, if the above-described inclination is measured on each raster in a two-dimensional plane including the focal area (in a three-dimensional volume in three-dimensional ultrasonic waves), the cross-sectional area (volume) of the degenerated area can be measured.

(Second Embodiment) As described above, the rate of decrease in the intensity of the focused ultrasonic wave was calculated from the intensity ratio between the first received signal and the second received signal. The frequency information of the first received signal and the second received signal is described below. A method for calculating the rate of decrease in the intensity of the focused ultrasonic wave from the following will be described. The configuration of the device is the same as that of FIG. However, the comparison means 1
3 is different from that of FIG. FIG. 4 shows the processing flow.

After the first and second received signals are subjected to Fourier transform, they are stored in a memory (not shown) in the comparing means 13. next,
The magnitude of the energy density spectrum at a certain frequency or the integration of the energy density spectrum within a certain frequency range is performed on the signals 1 and 2, respectively, and the signal 1
And the ratio of 2. Regarding the selection of the frequency, the frequency at which the energy density spectrum of the ultrasonic wave emitted from the piezoelectric element group 2 and the imaging ultrasonic probe 3 is the largest, or the nominal center frequency of reception of the ultrasonic wave for imaging and the piezoelectric element group 2 The resonance frequency may be used, or the frequency may be adjusted to one of the frequencies. However, a reference value for comparison is required in any case. For example, a shield existing in the propagation path of the ultrasonic wave radiated from the piezoelectric element group 2 by comparing the original data acquired in a known situation such as underwater as a reference value, and comparing this with data actually acquired in clinical practice. Alternatively, the rate of decrease in the intensity of the focused ultrasonic wave due to the strong absorber is roughly estimated. Subsequent operations are the same as those described above.

When frequency information is used as described above, the Doppler mode of the ultrasonic diagnostic apparatus can be used.
Now, as a general case, from the piezoelectric element group 2 to 1 to 3
It is assumed that an ultrasonic pulse of [MHz] is irradiated from the ultrasonic probe for imaging 3 with an ultrasonic pulse of 3.5 to 7.5 [MHz].

In such a case, the frequency detected in the Doppler mode is adjusted to the ultrasonic frequency of the piezoelectric element group 2 or its harmonic frequency, and the ultrasonic probe 3 for imaging is used.
If the ultrasonic wave emitted from the above is processed by a receiving circuit for reconstructing a normal ultrasonic tomographic image, the reflected signals by the above two types of ultrasonic pulses can be obtained without configuring a special receiving circuit or the like. It can be obtained with a commercially available device.

In such a case, the two ultrasonic pulses are separated and acquired by using the frequency difference between the two ultrasonic pulses, so that the two types of ultrasonic pulses can be irradiated simultaneously. of course,
If a special filter circuit or the like is provided or a time difference is applied to irradiate the above-described two types of ultrasonic pulses, it is possible to obtain the rate of decrease in the intensity of the focused ultrasonic wave due to the amplitude or intensity.

(Third Embodiment) Next, a third embodiment is shown in FIG. The blocks having the same numbers have the same operations and functions as those in FIG. A synchronization circuit 51 inserted between the control means 12 and the ultrasonic imaging device 8 or the waveform generating means 11 is for performing ultrasonic intensity distribution imaging described in Japanese Patent Application No. 8-70206. The control unit 12 controls the output timing of the ultrasonic pulse emitted from the piezoelectric element group 2 via the synchronization circuit 51 so that the intensity distribution imaging is performed accurately and stably.

In this embodiment, in order to obtain the distribution state of the ultrasonic pulse irradiated from the piezoelectric element group 2 in the patient 6, the irradiation timing of the ultrasonic pulse and the irradiation from the ultrasonic probe 3 for imaging are performed. The irradiation timing of the ultrasonic pulse is controlled. When determining these irradiation timings, it is necessary to know the amount of projection of the imaging ultrasonic probe 3 with respect to the piezoelectric element group 2.

As shown in FIG. 5, the propagation medium 5 in the water bag 4
A temperature sensor 52 for measuring the temperature of the piezoelectric element 2 and a means 53 for measuring the amount of projection of the ultrasonic probe for imaging 3 with respect to the piezoelectric element group 2, and the sound velocity in the propagation medium 5 is calculated by the calculation means 54 from these measured values. , And the control means 1
Send to 2. The synchronization circuit 51 outputs a signal from the control unit 12 so that the imaging ultrasonic pulse is emitted when the ultrasonic pulse emitted from the piezoelectric element group 2 coincides with the ultrasonic emission surface of the imaging ultrasonic probe 3. Based on the above, each ultrasonic irradiation timing signal is created.

Alternatively, the timing of the ultrasonic pulse irradiated from the piezoelectric element group 2 is controlled based on the timing signal from the control means 12 and the ultrasonic imaging device 8.
When intensity distribution imaging is performed using a color Doppler tomography apparatus, an ultrasonic pulse for intensity distribution imaging is applied from the piezoelectric element group 2 only when an ultrasonic pulse for color Doppler is applied. It may be. In this case, the number of pulse irradiation can be reduced.

The temperature sensor 52 is made of an ultrasonic non-absorber so that the ultrasonic wave from the piezoelectric element group 2 does not cause an error in the measured temperature. By the way, Japanese Patent Application Hei 8-70
The ultrasound intensity distribution imaging is performed as described in US Pat. No. 206, and a focal region is drawn in the treatment target region 7 in the patient 6. Next, a position where the ultrasonic intensity is the highest in the depicted focal region is derived by the time gate, and the shield or the above-mentioned shield or intensity is obtained from the intensity or amplitude or the energy density spectrum of the received signal based on the reflected ultrasonic signal from that position. The rate of decrease in the intensity of the focused ultrasonic wave by the strong absorber is calculated. In addition, it is also possible to calculate the amount of decrease in focus intensity in consideration of the effect of attenuation. By thus using the ultrasonic intensity distribution imaging together, a reflected signal from the focal position can be obtained with certainty, so that the accurate decrease rate of the focal ultrasonic intensity can be roughly estimated. Next, the above calculation results are transferred to the control means 12 and displayed on the display means 14 or a CRT (not shown) in the ultrasonic imaging apparatus 8. Then, the electric energy applied to the piezoelectric element group 2 is adjusted to a desired form.

(Fourth Embodiment) Next, a fourth embodiment will be described with reference to FIG. Here, the detailed Ii / It calculation as described above is not performed, and the object is to detect the decrease in the focus intensity qualitatively by the operator.

In the present embodiment, the applicator 1, the amplifying means 10 and the waveform generating means 11 have the same configuration as in FIG. The ultrasonic imaging device 8 includes a pulse generation circuit 81 and a transmission circuit 82 for generating an ultrasonic pulse for imaging,
Preamplifier 8 which is a buffer and a preamplifier for a received signal
3, a filter circuit 84 for separating a received signal based on an ultrasonic pulse for imaging and an ultrasonic pulse emitted from the piezoelectric element group 2, an ultrasonic receiving circuit for imaging 85, a pulse wave receiving circuit 86 for a piezoelectric element group, and a digital scan It comprises a converter (DSC) 87 and a CRT 88.

Here, the filter circuit 84 is composed of, for example, a band-pass filter or a combination of a high-pass filter and a low-pass filter. The gain control circuit 89 adjusts the magnitude of the output of the imaging ultrasonic wave receiving circuit 85 and the magnitude of the output of the piezoelectric element group pulse wave receiving circuit 86 to a value specified by the input means 9 via the control means 12.

The memory 90 reads and writes the output of the ultrasonic wave receiving circuit 85 for imaging and the pulse wave circuit 86 of the piezoelectric element group. Next, details of an operation example according to the present embodiment will be described. Now, the irradiation timing of both pulses is adjusted so that the ultrasonic pulse for imaging is irradiated when the ultrasonic pulse irradiated from the piezoelectric element group 2 has just reached the ultrasonic irradiation surface of the ultrasonic probe 3 for imaging. Have been.

These pulses are reflected within the subject and received by the imaging ultrasonic probe 3. Therefore,
The received signal includes a signal for reconstructing a normal ultrasonic image in the subject and a signal based on an intensity distribution generated by the piezoelectric element group 2 in the subject.

After these signals are amplified via a preamplifier 83, they are separated into two types of signals by a filter circuit 84. Next, the signal derived from the ultrasonic pulse for imaging is guided to the ultrasonic wave receiving circuit 85 for imaging, and the signal derived from the piezoelectric element group 2 is guided to the pulse wave circuit 86 for piezoelectric element group. After that, for example, the output of the imaging ultrasonic receiving circuit 85 is converted into luminance information of a plurality of black and white gradations, and the output of the piezoelectric element group pulse wave circuit 86 is converted into color information, synthesized by the DSC 87 and displayed on the CRT 88. .

Here, the color information may be, for example, a signal of a plurality of gradations of a single color, information of a plurality of colors, or a combination thereof. Further, a signal for displaying a monochrome contour line instead of the color information may be used. As a result, an image (hereinafter, a focus image) based on the ultrasonic intensity distribution created by the piezoelectric element group 2 is superimposed on an ultrasonic image (hereinafter, a B-mode image) inside the living body, and is displayed on the CRT 88.
Here, the signal intensity received by the imaging ultrasonic probe 3 is the same because the attenuation due to the ultrasonic absorption of the living body and the influence of the presence of the shield differ depending on the individual difference of the patient 6 and the type of the imaged region. There is variation even in depth.

Normally, the operator operates the B
The output of the imaging ultrasonic receiving circuit 85 is controlled so that the mode image is most visible.

In this embodiment, this output control is linked with the output control of the piezoelectric element group pulse wave circuit 86 to reconstruct a composite image of both. First, conditions such as the intensity of a received signal for rendering an appropriate B-mode image and a focal image for achieving appropriate heating of the focal region are recorded in a memory (not shown) or the like. This default value is input at the factory when the device is shipped, but may be changed by the operator. Now, at the actual treatment site, when the operator performs gain control so that the B-mode image is easy to see, the display intensity of the intensity distribution focus image is adjusted in conjunction with the gain control. At that time, the piezoelectric element group 2
If there is no shield such as a rib or an absorber of ultrasonic waves in the propagation path of the ultrasonic pulse emitted from the camera, an assumed appropriate focus image is displayed, but the shield or absorber exists. In this case, the intensity of the ultrasonic pulse from the piezoelectric element group 2 is weakened, and the focus image becomes difficult to see. For this reason, the operator can understand that it is difficult to perform the treatment as it is. Although the ultrasound imaging apparatus 8 in FIG. 6 includes blocks in a region surrounded by a solid line, the ultrasound imaging device 8 may be expanded to include all the blocks in a region indicated by a dotted line. Also,
The gain control is performed by using so-called sensItivI
It may be replaced by, or linked with, a time time control (STC). Further, in the present embodiment, the filter circuit 84 is configured by a band-pass filter or a combination of a high-pass filter and a low-pass filter. However, other means may be used as long as the two types of signals can be separated. A circuit may be used. In that case, a B-mode processing system and a color Doppler processing system will be used, and the gain control of both will be used in conjunction. Also, note that the effect of the attenuation of the ultrasonic wave by the living body depends on the frequency, and this may be used after being corrected.

As described above, several methods for determining the reduction rate of the focal intensity due to the ultrasonic shield or absorber have been described. However, these methods are not limited to the focal region, but may be applied to various parts or the whole within the subject. Applicable.

(Fifth Embodiment) Up to now, this is an effective method mainly for attenuation based on ultrasonic absorption of a living body. Next, a method for correcting and displaying a difference in reflection coefficient for each tissue of a living body will be described. The above-mentioned second equation uses the ultrasonic pulse radiated from the imaging ultrasonic probe 3 and the piezoelectric element group 2 to calculate the ratio of the original ultrasonic intensity at the site of interest from the ratio of the received signal reinforcement Ri and Rt. It was the technique I wanted. Here, this is extended to Japanese Patent Application No. 8-702.
In connection with the ultrasonic intensity distribution imaging method described in Japanese Patent Application Publication No. 06-2006, a method for correcting the reflectance dependency of a tissue when a focal region is drawn will be described. This method can be applied to a region other than the focal point, and reliably draws the ultrasonic beam pattern from the piezoelectric element group 2. Now, by transforming equation (2),

(Equation 3)

Here, k (f, x) is a function related to the frequency and the distance x. Regarding the reflection and the attenuation, the frequency of the ultrasonic pulse from the ultrasonic probe 3 for imaging and the frequency of the ultrasonic pulse irradiated from the piezoelectric element group 2 are calculated. This is a term for correcting the difference. n is each point in the imaging cross section in the subject, and it is assumed that, for example, n increases sequentially from the ultrasonic wave incident surface. Then, the intensity distribution Itn generated by the ultrasonic waves emitted from the piezoelectric element group 2 in the subject is

(Equation 4)

Is obtained. Here, Ii0 is the intensity of the ultrasonic pulse emitted from the imaging ultrasonic probe 3 on a certain reference point, for example, the surface of the subject, and is attenuated due to biological absorption, scattering, and diffusion every time Xn propagates. .

As is apparent from the above equation (7), the ultrasonic intensity Itn in the subject of the ultrasonic pulse irradiated from the piezoelectric element group 2 is determined by the ultrasonic probe 3 for imaging.
Can be described by the received signal strengths Rtn and Rin, a correction term based on a difference in frequency, a constant Ii0, and an attenuation term. Therefore, the relative intensity distribution of Itn is obtained from these.

FIG. 7 shows an embodiment for obtaining Itn. Here, the configuration given the same number as in FIG. 6 has the same function, and the description is omitted. However, it is assumed that the STC circuit is not built in the imaging ultrasonic wave receiving circuit 85 and the piezoelectric element group pulse wave circuit 86 in FIG.

The imaging ultrasonic receiving circuit 85 has two outputs, one of which is input to the DSC 87 via the STC circuit 95 and the display ratio control circuit 96 to reconstruct a grayscale two-dimensional ultrasonic image ( B-mode image).

The other one is inputted to the reciprocal circuit 93 in order to reconstruct the ultrasonic intensity distribution of the ultrasonic pulse emitted from the piezoelectric element group 2 in the subject. Regarding the reconstruction of the B-mode image, the operator controls the output of the STC circuit 95 via the control unit 12 so that the brightness of the ultrasonic image becomes appropriate so as to correct the effect of ultrasonic attenuation due to the ultrasonic absorption of the living body. Adjust. Now, the reciprocal circuit 91 detects the received signal strength Ri after detection.
n is a circuit that outputs the reciprocal of n. A multiplication circuit 92 outputs the output of the reciprocal circuit 91 and the output Rt of the piezoelectric element group pulse wave circuit 86.
Output the multiplied value of n. Next, the output of the multiplication circuit 92 is input to the frequency difference correction circuit 93. This circuit is specifically an amplifier, and is controlled by the control means 12 so that the amplification factor is determined by the equation (4).

The output signal from the frequency difference correction circuit 93 is input to the inverse STC circuit 94. This circuit is for correcting the attenuation term (e- ^2αx ) in the equation (7), and the amplification factor of the circuit is controlled by the control means 12 based on the value adjusted by the STC circuit 95. Is done. Specifically, the operator controls the STC via the input unit 9 so that the B-mode image can be easily viewed. Here, the term (e ^−2αx ) in the equation (7) relates to the attenuation received when the ultrasonic wave propagates through the distance x, and the ultrasonic pulse emitted from the imaging ultrasonic probe 3 is emitted from the object. The signal is attenuated until it is reflected and received by the probe 3, that is, a distance corresponding to twice the distance from the probe 3 to the target.

After all, the attenuation correction by the STC corrects the attenuation for twice the distance. This is equivalent to approximately ^multiplying the received signal Rin by ^e4αx . Here, the coefficient of α is 4 because of the attenuation due to the reciprocation of the ultrasonic beam. On the other hand, in order to obtain Itn, it is necessary to correct only the attenuation for a one-way distance. Therefore, the correction amount by STC, that is, e ^4αx
Is obtained to obtain e ^{2 αx,} and the gain of the inverse STC circuit 94 is controlled. In other words, the gain correction curve for the distance (depth) is changed from a curve adjusted based on ^e4αx of the STC to a curve adjusted based on ^e2αx . This is specifically realized by taking the square root of the STC curve (correction curve for distance).

From the above, the expression (7) is realized, and the normalized distribution of the ultrasonic intensity distribution that has been subjected to accurate attenuation correction can be extracted from the output of the inverse STC circuit 94. This is output to the DSC 87 and superimposed on the B-mode image, and the CRT 88
Display above. Here, the order of the multiplication circuit 92, the frequency difference correction circuit 93, and the inverse STC circuit can be changed.

Although the input of the multiplication circuit 92 uses the signal after detection, the signal before detection may be used. The display ratio control circuit 96
Controls the display ratio of the B-mode image and the ultrasonic intensity distribution image. Further, the configuration of FIG. 7 can be configured by an analog circuit or a digital circuit. When the ultrasonic pulse emitted from the imaging ultrasonic probe 3 and the ultrasonic pulse emitted from the piezoelectric element group 2 are alternately temporally alternate, a signal is stored in each raster or ultrasonic two-dimensional image for one screen. 90, etc., and the above-described invention may be realized by sequentially calling and processing.

In the embodiments described above, the relative values of the intensity distribution of the ultrasonic pulse from the piezoelectric element group 2 in the subject are displayed. Here, a certain reference value is set in advance, and the absolute value of the focus intensity can be obtained by comparing with the reference value. That is, in a situation where the characteristics are known, for example, underwater or in a phantom, a reference value of the focus intensity is obtained from the transmission ultrasonic intensity, the attenuation factor, the reflection coefficient, and the like, and stored in a memory or the like. Based on this value,
In equation 7, Ii0 is determined so that both sides are connected by an equal sign. Next, the actual ultrasonic coefficient in the subject is calculated, for example, from the attenuation ratio of the imaging ultrasonic signal as described above, and the focal intensity and the intensity at each point are obtained by the equation (7) in which Ii0 is adjusted.

Thus, the electric energy to be applied to the piezoelectric element group 2 is adjusted so that the focus intensity becomes a value suitable for the treatment, and the ultrasonic burst for treatment is irradiated. that time,
For example, the lower limit value of the focus intensity necessary to achieve the cauterization of a certain focus area is recorded in advance in the memory 90 or the like, and this is made to match a threshold value at which the focus is drawn, or a certain size. By making the time when the focus image is drawn coincide with the lower limit described above, the operator can immediately check whether the focus intensity is suitable for treatment by checking the focus image displayed on the CRT 88. become able to.

If the depiction of the focal region is insufficient,
This means that the focus intensity is insufficient, and the operator increases the output of the piezoelectric element group pulse wave circuit 86 until the focus image is reliably drawn. Then, the electric energy to be applied to the piezoelectric element group 2 is calculated backward from the increase amount. Note that, instead of controlling the output of the piezoelectric element group pulse wave circuit 86 as described above, the energy of the electric pulse applied to the piezoelectric element group 2 may be increased. However, in that case, the propagation distance of the ultrasonic wave is about twice as long as the distance from the region of interest to the ultrasonic probe for imaging 3, so the frequency correction and attenuation are recalculated as the distance 1/2, and Determine the input electrical energy.

In the above embodiment, the case where the focus intensity is weaker than the reference value has been mainly described. However, the reverse operation is also possible. When the ultrasonic pulse for imaging and the ultrasonic pulse from the piezoelectric element group 2 are alternately irradiated, the respective image information is temporarily stored in the memory 90, and the two are overlapped by the DSC 87. Instead, a switch circuit for switching the pulse output is incorporated.

It should be noted that Japanese Patent Application No. 8-70206 discloses that the ultrasonic wave propagation path from the imaging ultrasonic probe 3 and the ultrasonic wave propagation path from the piezoelectric element group 2 are different from each other. Distortion occurs and a solution is described. In the present invention, this distortion correction method may be used in combination.

The present invention is not limited to the embodiments described above, but can be implemented with various modifications.

[0084]

According to the present invention, the first related to the reflected wave of the therapeutic ultrasonic wave received by the ultrasonic probe for imaging.
Using the comparison result between the received signal and the second received signal related to the reflected wave of the imaging ultrasonic wave received by the imaging ultrasonic probe, the error in the spatial relative relationship of the in-vivo intensity of the therapeutic ultrasonic wave is reduced. obtain.

Further, based on the comparison result, it is possible to obtain the rate of decrease of the therapeutic ultrasonic wave due to the influence of the unknown shield or the strong absorber in the propagation path to the focal point of the therapeutic ultrasonic wave. Therefore, it is possible to appropriately adjust the intensity of the therapeutic ultrasonic wave to obtain a reliable and highly accurate therapeutic effect.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ultrasonic irradiation apparatus according to a first embodiment.

FIG. 2 is a flowchart showing a procedure of a process of calculating a rate of decrease from a received signal intensity to a focal point of a therapeutic ultrasonic wave by the control means of FIG. 1;

FIG. 3 is a diagram showing a change in a reflected wave according to the progression of degeneration of a tumor.

FIG. 4 is a flowchart showing a procedure of a process for obtaining a decrease rate of therapeutic ultrasonic waves according to the second embodiment.

FIG. 5 is a block diagram showing a configuration of an ultrasonic irradiation apparatus according to a third embodiment.

FIG. 6 is a block diagram illustrating a configuration of an ultrasonic irradiation apparatus according to a fourth embodiment.

FIG. 7 is a block diagram showing a configuration of an ultrasonic irradiation apparatus according to a fifth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Applicator, 2 ... Piezoelectric element group, 3 ... Ultrasonic probe for imaging, 4 ... Flexible water bag, 5 ... Propagation medium (water), 6 ... Patient, 7 ... Treatment target, 8 ... Ultrasonic imaging Device 9 input means 10 amplifying means 11 waveform generating means 12 control means 13 comparing means 14 display means 51 synchronous circuit 52 temperature sensor 53 probe position detecting means 54: calculation means, 55: memory, 81: pulse generation circuit, 82: transmission circuit, 83: preamplifier, 84: filter circuit, 85: ultrasonic receiving circuit for imaging, 86: piezoelectric element group pulse wave circuit, 87: DSC 88 CRT, 89 Gain control circuit, 90 Memory, 91 Reciprocal circuit, 92 Multiplication circuit, 93 Frequency difference correction circuit, 94 Reverse STC circuit, 95 TC circuit, 96 ... display ratio control circuit.

Claims (9)

[Claims] An ultrasonic irradiation unit configured to irradiate a therapeutic ultrasonic wave into an object; an imaging ultrasonic wave transmitting an imaging ultrasonic wave into the object and receiving a reflected wave from the object; A probe, a first reception signal related to a reflected wave of the therapeutic ultrasonic wave received by the imaging ultrasonic probe, and a second reception signal related to a reflected wave of the imaging ultrasonic wave received by the imaging ultrasonic probe. An ultrasonic irradiation device comprising: means for comparing 2. The method according to claim 1, wherein the comparing unit is configured to determine a point in the subject based on a first intensity ratio and a frequency ratio of the first received signal and the second received signal and an absorption coefficient in the subject. The ultrasonic irradiation apparatus according to claim 1, further comprising means for calculating a second intensity ratio between the treatment ultrasonic wave and the imaging ultrasonic wave in (1). 3. The method according to claim 2, wherein the comparing unit is configured to determine whether or not the second intensity ratio has been obtained in an environment where there is no obstruction, and an actual second intensity ratio obtained from the subject. 3. The ultrasonic irradiation apparatus according to claim 2, further comprising: means for estimating a decrease rate of said therapeutic ultrasonic wave between said point and said ultrasonic probe for imaging. 4. The apparatus according to claim 1, wherein the comparing means comprises: an intensity ratio between the first received signal and the second received signal; and a distance between the point in the subject and the ultrasonic probe for imaging. Means for estimating a spatial relative value of the intensity of the therapeutic ultrasonic wave at a point in the subject, based on the attenuation rate received and the transmission intensity of the imaging ultrasonic wave. Item 7. An ultrasonic irradiation device according to Item 1. 5. An ultrasonic wave according to claim 4, wherein said comparing means has means for estimating said attenuation rate based on a function of a gain curve for correcting attenuation depth dependency. Irradiation device. 6. The comparing means includes: an intensity ratio between the first received signal and the second received signal; a depth of a point in the subject; and transmission of the therapeutic ultrasound and the imaging ultrasound. Based on the frequency ratio, the absorption coefficient of the imaging ultrasound in the subject, and the transmission intensity of the imaging ultrasound, the absolute value of the intensity of the therapeutic ultrasound at a point in the subject. 2. The ultrasonic irradiation apparatus according to claim 1, further comprising: means for estimating. 7. The ultrasonic irradiation according to claim 1, wherein said comparing means includes means for comparing the intensity ratio between said first received signal and said second received signal with a predetermined value over time. apparatus. 8. An ultrasonic wave irradiating means for irradiating an ultrasonic wave for treatment into an object, an ultrasonic wave transmitting means for transmitting an ultrasonic wave for imaging into the object and receiving a reflected wave from the object. An ultrasonic probe, means for reconstructing an ultrasonic image in the subject based on an output from the imaging ultrasonic probe, and means for controlling operation timing of the ultrasonic irradiation means and the imaging ultrasonic probe. Comparing a first reception signal related to the reflected wave of the therapeutic ultrasonic wave received by the imaging ultrasonic probe with a second received signal related to the reflected wave of the imaging ultrasonic wave received by the imaging ultrasonic probe; Means for analyzing the frequency information of the first received signal, and means for displaying the frequency information and the comparison result. Ultrasonic irradiation equipment. 9. An ultrasonic wave irradiating means for irradiating a therapeutic ultrasonic wave into a subject, and an imaging ultrasonic wave transmitting an imaging ultrasonic wave into the subject and receiving a reflected wave from the inside of the subject. A sound wave probe, a first reception signal relating to a reflected wave of the therapeutic ultrasonic wave received by the imaging ultrasonic probe, and a second reception signal relating to a reflected wave of the imaging ultrasonic wave received by the imaging ultrasonic probe And a means for controlling a gain for the first reception signal in conjunction with a gain for the second reception signal.