Source: https://patents.google.com/patent/EP0734742B1/en
Timestamp: 2018-10-19 07:47:35
Document Index: 428899065

Matched Legal Cases: ['art 102', 'art 102', 'art 102', 'art 102', 'art 102', 'Application No. 4', 'Application No. 4', 'art 7', 'application No. 6', 'Application No. 6']

EP0734742B1 - Ultrasound therapeutic apparatus - Google Patents
Ultrasound therapeutic apparatus Download PDF
EP0734742B1
EP0734742B1 EP19960302221 EP96302221A EP0734742B1 EP 0734742 B1 EP0734742 B1 EP 0734742B1 EP 19960302221 EP19960302221 EP 19960302221 EP 96302221 A EP96302221 A EP 96302221A EP 0734742 B1 EP0734742 B1 EP 0734742B1
EP19960302221
EP0734742A2 (en )
EP0734742A3 (en )
Satoshi c/o K.K. Toshiba Aida
Katsuhiko c/o K.K. Toshiba Fujimoto
Yoshiharu c/o K.K. Toshiba Ishibashi
Mariko c/o K.K. Toshiba Shibata
Takuji c/o K.K. Toshiba Suzuki
A typical example of a strong ultrasound generating device is a piezoelectric type of device. This type of ultrasound generating device has great advantages that the focus of ultrasonic waves can be localized, few expendable parts are involved, intensity control is easy, the position of the focus can be changed easily by phase control (delay control) of drive voltages to a plurality of piezoelectric transducer elements, etc. (refer to Japanese Unexamined Patent Publication No. 60 - 145131 and U.S. Patent No. 4,526,168).
Under such circumstances, as one of therapies for malignant tumors, or cancers, the therapy by hyperthermia has drawn attention, which, using a difference in sensitivity to heat between tumor tissues and normal tissues, selectively destroys only cancer cells by heating a diseased part to 42.5°C or more for a long period of time. As a method of application of heat to the body, a method of using electromagnetic waves such as microwaves has preceded. With this method, however, the electrical characteristics of a living body make it difficult to selectively heating a tumor in the deep of the body. Satisfactory results cannot therefore be expected for tumors existing 5cm or more deep in the body. For this reason, a method of utilizing ultrasonic energy has been proposed for therapy for tumors existing in the deep of the body (refer to Japanese Unexamined Patent Publication No. 61 - 13955).
The ultrasound-based thermotherapy has been developed into a therapy which, by sharply focusing ultrasonic waves generated by piezoelectric transducer elements onto a diseased part, heats a tumor to 80°C or more and necrotizes tumor tissues in an instant (refer to U.S. Patent No. 5,150,711). In this therapy, unlike the conventional hyperthermia, it is a very important subject to precisely match the focus or point of application of focused ultrasonic waves with a diseased part in order to introduce ultrasonic waves at a very great intensity (some hundreds to some thousands of W/cm2) into a restricted region in the vicinity of the focus of the ultrasonic waves and necrotize the diseased part instantly.
Methods of solving that problem are disclosed in Japanese Unexamined Patent Publications Nos. 61 - 13954, 61 - 13956, and 60 - 145131. According to these methods, the spatial intensity distribution of therapeutic ultrasonic waves is obtained by first detecting by an imaging probe echoes from the focus region of the waves pulses emitted from a therapeutic ultrasonic source, and then performing a B-mode process on the received echo signal.
However, these methods have the following problem. Whereas the frequency of the therapeutic ultrasonic waves is in the range of 1 to 3MHz, the frequency of in vivo imaging ultrasonic waves is 3.5MHz or more. The resonant frequency of imaging transducer elements coincides with the frequency of the imaging ultrasonic waves. Thus, the imaging probe will receive echoes of therapeutic ultrasonic waves with a very low sensitivity, failing to obtain the intensity distribution with precision.
According to the present invention is provided an apparatus according to claim 1.
Preferred features of the present invention are defined in dependent claims 2 to 4.
FIG. 1 shows an arrangement of an ultrasonic therapeutic apparatus according to an embodiment of the invention;
FIG. 4 shows the difference between the timing of an in vivo imaging ultrasonic pulse and the timing of an intensity distribution imaging ultrasonic pulse;
FIG. 5 shows an arrangement of an ultrasonic therapeutic apparatus according to a first example useful for understanding the invention;
FIG. 6 shows an arrangement of an ultrasonic therapeutic apparatus according to a second example useful for understanding the invention;
FIG. 10 shows an arrangement of an ultrasonic therapeutic apparatus according to a third example useful for understanding the invention;
FIG. 12 shows an arrangement of an ultrasonic therapeutic apparatus according to a fourth example useful for understanding the invention;
FIG 13. is a schematic representation of a source of therapeutic ultrasonic waves;
FIG. 17 shows an arrangement of an ultrasonic therapeutic apparatus according to a fifth example useful for understanding the invention;
FIG. 19 shows an arrangement of an ultrasonic therapeutic apparatus according to a sixth example useful for understanding the invention;
FIGS. 20A and 20B are diagrams for use in explanation of problems which are solved by an ultrasonic therapeutic apparatus according to a seventh example useful for understanding the invention;
FIG. 23 is a diagram for use in explanation of a second method of solving the problems associated with FIGS. 20A and 20B,
FIG 27 shows an arrangement of an ultrasonic therapeutic apparatus according to an eighth example useful for understanding the invention;
FIG. 37 shows an arrangement of an ultrasonic therapeutic apparatus according to a ninth example useful for understanding the invention;
FIG. 40 shows an arrangement of an ultrasonic wave application apparatus according to a tenth example useful for understanding the invention;
FIG. 42 shows a modification of the arrangement of FIG. 40 (the eleventh example useful for understanding the invention) ;
FIG. 46 shows an arrangement of an ultrasonic wave application apparatus according to a twelfth example useful for understanding the invention;
FIG. 49 shows an arrangement of an ultrasonic wave application apparatus according to a thirteenth example useful for understanding the invention;
The piezoelectric transducer elements of the imaging probe 16 have peaks of sensitivity in both a low-frequency band containing the first fundamental frequency f1 of the ultrasonic waves for therapy and intensity distribution and a high-frequency band containing a second fundamental frequency f2 for imaging ultrasonic waves. For this reason, the piezoelectric elements of the probe 16 are fabricated to have a two-layer structure or a hybrid structure, as disclosed in Japanese Unexamined Patent Publication No. 4 - 211599. With the two-layer structure, an array of piezoelectric elements having a thickness corresponding to the first fundamental frequency f1 and an array of piezoelectric elements having a thickness corresponding to the second fundamental frequency f2 are stacked one on top of the other with a common electrode sandwiched therebetween. With the hybrid structure, an array of piezoelectric elements of a thickness corresponding to the first frequency f1 and an array of piezoelectric elements of a thickness corresponding to the second frequency f2 are juxtaposed. Each piezoelectric element is coated on top and bottom with electrode metal.
The synchronization circuit 18 applies a second sync signal to a transmission circuit 17 that includes a pulse generator, a transmit delay circuit, and a pulser. The pulse generator periodically generates signal pulses of the second fundamental frequency f2 in response to the second sync signal. The second frequency f2 is different from the first frequency f1 and coincides with a resonant frequency corresponding to the thickness of the piezoelectric elements of the probe 16. It is assumed here that the frequency f2 is higher than the frequency f1. The second frequency is 3.5MHz by way of example. The signal pulses are distributed to the respective channels and imparted, in the transmit delay circuit, with a different delay time for each channel so as to focus ultrasonic waves into a beam and steer a focused beam of ultrasonic waves in a desired direction. The delayed signal pulses are then fed into the pulser. The pulser amplifies the signal pulses and produces drive pulses which are applied to the piezoelectric elements of the imaging probe 16. Thus, in vivo imaging ultrasonic waves are produced. Echoes of the ultrasonic waves are received by the imaging probe 16. Received echo signals are applied through a preamplifier circuit 19 to a receive delay circuit 20 for each channel. The receive delay circuit 20 provides different delay times to the received echo signals each associated with a respective one of channels and sums the received echo signals, thereby determining receive directivity.
The output signal of the receive delay circuit 20 is also applied through the echo filter 21 to a pulsed Doppler unit 27, which comprises a quadrature detector, an analog-to-digital converter, an MTI filter, an autocorrelator, and an operation unit and produces a color Doppler image data. This image data is displayed on the CRT 29 after being processed by the digital scan converter 28.
FIG. 5 shows an arrangement of an ultrasonic therapeutic apparatus according to a first example useful for understanding the invention. In this figure, like reference numerals are used to denote corresponding parts to those in FIG. 1 and description thereof is omitted.
Accordingly, the first example provides the same advantages as the embodiment of the invention.
FIG. 6 shows an arrangement of an ultrasonic therapeutic apparatus according to a second example useful for understanding the invention. In this figure, like reference numerals are used to denote corresponding parts to those in FIG. 1 and description thereof is omitted.
As with the embodiment of the invention, in the present example, the time of generating ultrasonic waves for imaging intensity distribution from the source 2 and the time of generating ultrasonic waves for ultrasonic imaging from the probe 16 are adjusted so that both the ultrasonic waves will arrive at the focus simultaneously. The present example is intended to improve the precision of this simultaneity.
The function of the equalizer 51 will be described with reference to FIG. 8. The spectral characteristic of echoes of ultrasonic waves for imaging intensity distribution is high in the fundamental frequency band centered at the first frequency f1 and harmonic frequency bands each centered at a frequency that is an integral multiple of the first frequency f1 (n × f1). The sensitivity characteristic of the probe 16 is high at the second fundamental frequency f2. The spectrum of the received signal by the probe 16 is represented as a product of the frequency spectrum of echoes of ultrasonic waves for imaging intensity distribution and the frequency characteristic of the probe 16. The equalizer 51 shapes the received signal spectrum so as to approximate to the echo spectrum.
The system controller 9 applies the absorption factor, the thermal conductivity, the intensity of the therapeutic ultrasonic waves, and the irradiation time to the heat transport equation to presume the temperature quantitatively. This presumption is performed on multiple points in the vicinity of the focus. Thereby, the spatial distribution of the presumed temperatures, i.e., the temperature distribution, is produced. The temperature distribution is displayed superimposed on a tomographic image of tissues on the CRT 29. An area that is at temperatures above the temperature at which cancer cells thermally affected and necrotize (i.e., treated region at about 50 to 60 C or more) may be extracted from the temperature distribution and displayed encircled by a continuous or dotted line, colored, or half-tone dot meshed. The operator can predict regions that will be thermally metamorphosed, regions that will suffer damage, etc., on the basis of the temperature distribution.
Further, with the present example, it is possible to seek drive energy required to obtain the intensity of therapeutic ultrasonic waves at the focus (first focus intensity) that is necessary for therapy, i.e., the magnitude of a drive signal to be applied to the second piezoelectric transducer elements of the therapeutic ultrasonic transducer. This is due to the fact that, in the present invention, the intensity at the focus can be measured quantitatively. The drive energy (second drive energy) at the time of imaging of intensity distribution and the resulting intensity at the focus (second focus intensity) are stored in the memory 45. There is a substantially proportional relationship between the focus intensity and the drive energy. Thus, the first drive energy is calculated by multiplying the second drive energy and the result of division of the first focus intensity by the second focus intensity. This calculation is performed by the system controller 9. The first focus intensity can be obtained by producing a drive signal according to the first drive energy thus obtained.
(Third Example Useful for Understanding the Invention)
FIG. 10 shows an arrangement of a principal part of an ultrasonic therapeutic apparatus according to a third example useful for understanding the invention. In FIG. 10, like parts to those in FIG. 7 and description thereof is omitted. A filter 70 is provided to precede the frequency spectrum analyzer 52 with a switch 71 interposed therebetween. The filter is intended to remove chiefly blood-flow-shifted components from a received signal. The blood-flow Doppler effect shifts the frequency of ultrasonic waves by about several kilohertzs. As shown in schematically FIG. 11, the shift bands in which a shift occurs are defined as bands centered at frequencies that are several kilohertzs above and below the first fundamental frequency f0 and bands centered at frequencies that are several kilohertzs above and below the second fundamental frequency f2.
The filter 70 sufficiently attenuates or remove the shifted components within these shift bands. The filter is constructed from a plurality of highpass filters and a plurality of lowpass filters. The filter need not limited to this arrangement as long as it has a function of sufficiently attenuating the shifted components within the shift bands. The shifted components that are slightly offset from the fundamental frequencies are removed by the filter 70. The ultrasonic waves for in vivo imaging and the ultrasonic waves for intensity distribution imaging are 1MHz or more apart from each other and contain harmonic components to cover a very broad range. Thus, even if the shifted components are removed, the signal intensity will not be decreased extremely, thus keeping high image quality. The adjustment of bands that the filter 70 eliminates permits shifted components resulting from moving objects, such as heart walls, other than blood flow to be eliminated.
(Fourth Example Useful for Understanding the Invention)
FIG. 12 shows an arrangement of an ultrasonic therapeutic apparatus according to a fourth example useful for understanding the invention. In this figure, like reference numerals are used to denote corresponding parts to those in FIG. 6. A therapeutic ultrasonic transducer 80 is arranged, as shown in FIG. 13, such that a piezoelectric transducer element 81 in the form of a disk is divided in the direction of radius and in the direction of circumference. In other words, the transducer 89 is arranged such that a plurality of piezoelectric elements 81 are arranged in the form of a disk. A single piezoelectric element 81 is described herein as forming one channel. Of course, a plurality of adjacent piezoelectric elements may form one channel.
Suppose here that the maximally heated region 103 is displaced from a diseased part 102 as shown in FIG. 15. In this example, a three-dimensional ultrasonic image is produced. Techniques of producing three-dimensional ultrasonic images are well known as disclosed in Japanese Unexamined Patent Publications Nos. 61 - 209643 and 5 - 300910 and hence description thereof is omitted herein. On the CRT 29 are displayed a three-dimensional ultrasonic image, three-dimensional coordinate axes 101, the diseased part 102, and three-dimensional coordinates 104 representing the maximally heated region 103. This three-dimensional coordinate system is such that its origin (0, 0, 0) is placed at a point 105 on the three-dimensional image. Suppose that the coordinates of the diseased part 102 are (0, 8, 0) and the coordinates of the maximally heated region 103 (-1, 6, 0). On the basis of spatial displacement of the maximally heated region 103 with respect to the diseased part 102, the system controller 9 controls the synchronization circuit 18, so that intensity distribution imaging is carried out with delay control adjusted. This operation is repeated until coordinate matching is achieved between the maximally heated region 103 and the diseased part 102. When the coordinate matching is effected, treatment is initiated under the delay control at that time.
(Fifth Example Useful for Understanding the Invention)
FIG. 17 shows an arrangement of an ultrasonic therapeutic apparatus according to a fifth example useful for understanding the invention. In this figure, like reference numerals are used to denote corresponding parts to those in FIGS. 1 and 12. A number of piezoelectric transducer elements constituting a therapeutic ultrasonic transducer 2 can each be driven individually by a corresponding driver 120. Drivers 120 are connected the system controller 9 and a driving power supply 121 and responsive to control signals from the system controller to apply a drive signal to a corresponding one of the piezoelectric elements.
Treatment for calculus will be described herein. In order to focus therapeutic ultrasonic waves onto a calculus, a diseased part (calculus) is first determined on an ultrasonic image reconstructed by the ultrasonic image diagnostic section 40 on a received signal acquired by the imaging probe 16. The position of the diseased part is entered by the operator via the console 10. The coordinates of the diseased part are calculated by the system controller 9. On the calculated coordinates of the diseased part, the system controller 9 calculates the difference in drive timing among the piezoelectric elements, i.e., delay times associated with the respective piezoelectric elements, so that the therapeutic ultrasonic waves will be focused on the diseased part. The entry of the position of the diseased part may be made by an automatic detection and entry system as disclosed in Japanese Patent Application No. 4 - 261420.
In the present example, the coordinates of the diseased part are corrected on the basis of the amount of deviation. The delay times associated with the piezoelectric elements are calculated as conventional so that the focus will be formed in the corrected coordinate position. Thereby, the focus of the therapeutic ultrasonic waves can be matched to the diseased part with high precision. In the memory 45 there are stored the distance from the reference line, the intensity of ultrasonic waves (magnitude of drive signals), and the amount of deviation in combination. The system controller 9 seeks the distance between the position of a specified diseased part and the reference line, reads the amount of deviation corresponding to the distance and the intensity of ultrasonic waves (magnitude of drive signals) from the memory 45, corrects the position of the diseased part according to the amount of deviation, and calculates the delay times associated with the piezoelectric elements so that the focus will be formed in the corrected position. In addition, the memory 45 may store the distance from the reference line, the intensity of ultrasonic waves, and correction values for delay times corresponding to the amount of deviation in combination. In this case, the delay times calculated as conventional for the piezoelectric elements are corrected according to the correction values so that the ultrasonic waves will be focused onto the diseased part.
(Sixth Example Useful for Understanding the Invention)
FIG. 19 shows an arrangement of a tracking type of ultrasonic therapeutic apparatus according to a sixth example useful for understanding the invention. In this figure, like reference numerals are used to denote corresponding parts to those in FIG. 17. A technique of allowing the focus of therapeutic ultrasonic waves to track a diseased part that moves with respiration movement, such as a kidney calculus, employing the phased array technology is known as disclosed in Japanese Patent Publication No. 6 - 26549. A diseased part position detector 140 detects the position of a diseased part in real time. This detection technique is also known as disclosed in Japanese Patent Application No. 4 - 261420. For example, the position of a diseased part can be detected by taking the difference between two successive frames of an ultrasound- or CT-based image. Or, the position of a peak in echoes of ultrasonic waves can be detected as the position of a calculus.
The position detector 140 applies the position information of a diseased part to the system controller 9 constantly or periodically. The delay times associated with the piezoelectric elements are calculated so that the focus will be formed in the position of the diseased part. At this point, by usinq the correction described in connection with the fifth example useful for understanding the invention, the focus is permitted to track the diseased part with high precision.
(Seventh Example Useful for Understanding the Invention)
The seventh example useful for understanding the invention is intended to eliminate noise mixed in an ultrasonic image reconstructed during treatment. The noise reduction is achieved by the ultrasonic diagnostic section 40 in the above-described embodiment.
As shown in FIG. 20A, therapeutic ultrasonic waves are generated as burst waves at a first period. In vivo imaging ultrasonic pulses are generated at a second period that is considerably shorter than the first period. Echoes of each ultrasonic pulse are received prior to the transmission of the next ultrasonic pulse. The transmission/reception of imaging ultrasonic waves is repeated for N rasters. A scan is defined as a transmission/reception operation for one frame which repeats the transmission/reception of ultrasonic waves N times while changing the rasters from one to another. The echoes of the therapeutic ultrasonic pulses are significantly strong in comparison with those of imaging ultrasonic pulses. The reception gain is set for the echoes of the imaging ultrasonic pulses. For this reason, when a scan and application of therapeutic ultrasonic bursts are performed simultaneously, portions 153 of an ultrasonic image 150 that corresponds to the intervals when the high-intensity therapeutic ultrasonic waves (barst) are generated will be displayed as a region of extremely high luminance. The seventh example useful for understanding the invention provides several methods of removing the noise. One of the methods may be used in the apparatus; otherwise, all the methods may be incorporated into the apparatus so as to allow the operator to optionally select a desired one.
(Eighth Example Useful for Understanding the Invention)
FIG. 27 shows an arrangement of an ultrasonic therapeutic apparatus according to an eighth example useful for understanding the invention. In this embodiment, the ultrasonic therapeutic apparatus is combined with a magnetic resonance diagnostic apparatus. In the ultrasonic thermotherapy, it is important to realize highly precise positional matching between a diseased part and a heated region prior to the initiation of treatment.
The magnetic resonance diagnostic apparatus can measure the temperature distribution by employing the temperature dependence of chemical shifts and the relaxation time T1 (Y.Ishihara et al, Proc. 11th Ann. SMRM Meeting, 4803, 1992; H.Kato et al "Possible application of noninvasive thermometry for hyperthermia using NMR", International Conference on Cancer Therapy by Hyperthermia, Radiation and Drugs, Kyoto, Japan, Sept. 1981).
In addition, the magnetic resonance diagnostic apparatus can measure a local region or a region of an arbitrary shape (C.J.Mardy and H.E.Cline, Journal of Magnetic Resonance, vol. 82, pp. 647 to 654, 1989; J.Pauly et al, "Three-Dimensional π Pulse", Proc. 10th Ann. SMRM Meeting, 493, 1991).
The object of the eighth example useful for understanding the invention is to make it possible to monitor the temperature at high time resolution.
According to the eighth example useful for understanding the invention, the ultrasonic therapeutic apparatus using MRI permits the temperature of a diseased part to be measured accurately during therapy and the temperature distribution to be acquired at high speed.
(Ninth Example Useful for Understanding the Invention)
FIG. 37 shows an arrangement of an ultrasonic application apparatus according to a ninth example useful for understanding the invention. In this figure, like reference numerals are used to denote corresponding pats to those in FIGS. 1 and 6 and description thereof is omitted. The ultrasonic diagnostic section 40 is provided with an MTI (Moving Target Indication) operation unit 400, which comprises a quadrature detector, an A/D converter, an MTI filter, an autocorrelator, and an operation unit and acquires two-dimensional distribution of movement information about a moving target, such as blood flow, on the basis of the phase difference between received signals due to the motion of the target. The two-dimensional distribution of the movement information is displayed in color on the display in the ultrasonic diagnostic section 40. The MTI operation unit 400 is well known to those skilled in the art and hence the detailed description thereof is omitted here. For example, refer to Medical Ultrasonic Equipment Handbook edited by Electronic Industries Association of Japan, pp. 172 to 175, Corona company, Tokyo.
The timing signal generator 180 is responsive to the first sync signal 101 to produce a second sync signal 102, which is defined as a pulse train of pulses with a predetermined duration and the same period as the first sync signal 101. The ultrasonic waves for imaging the intensity distribution are applied at the leading edge of the second sync signal 102. Hence, the first and second sync signals are out of sync. The time difference between the first and second sync signals is set to dt. This time difference is adjusted by the system controller 9 so that in vivo imaging ultrasonic waves and ultrasonic waves for imaging the intensity distribution arrive at the focus at the same time. The basis of calculating the time difference dt is the same as the method described in connection with the first embodiment and first example useful for understanding the invention.
Thus, the phase of a received echo signal is changed at each ultrasonic pulse for intensity distribution imaging .
(Tenth Example Useful for Understanding the Invention)
FIG. 40 shows an arrangement of an ultrasonic application apparatus according to a tenth example useful for understanding the invention. In this figure, like reference numerals are used to denote corresponding parts to those in FIGS. 1, 6, and 37. The ultrasonic diagnostic section 40 has a B-mode processing system and an intensity distribution system which share a transmitter/receiver 402, a digital scan converter 412, and a CRT 413.
The quadrature phase detector 414 comprises a mixer 404 and a lowpass filter 406 to extract from the received signals the components in the highest energy band associated with ultrasonic waves for imaging intensity distribution (high energy band components). The high energy band components are components in the band (fundamental wave band) centered at the fundamental frequency f1, i.e., the fundamental wave components, or components in a band (harmonic wave band) centered at a higher frequency that is an integral multiple of the fundamental frequency f1, i.e., the harmonic wave components. The mixer 405 multiplies the received signals from the transmitter/receiver 402 and a reference signal of a reference frequency from a signal generator 502. The reference frequency is the fundamental frequency, f1, of the therapeutic ultrasonic waves or a frequency that is an integral multiple of f1, i.e., n × f1.
(Eleventh Example Useful for Understanding the Invention)
FIG. 42 shows an arrangement of an ultrasonic therapeutic apparatus according to an eleventh example useful for understanding the invention. In this figure, like reference numerals are used to denote corresponding parts to those in FIGS. 1, 6, 37, and 40 and description thereof is omitted.
As with the ninth example useful for understanding the invention, in order to allow the intensity distribution to be produced from MTI filter outputs, a jitter imparting circuit 608 is connected between a timing signal generator 180 and a waveform generator 460, which imparts a jitter to a sync signal 102 that determines the timing of ultrasonic pulses for intensity distribution imaging. Instead of providing the jitter imparting circuit, the MTI operation unit may be disconnected at intensity distribution imaging time. In this case, the number of times of transmission per raster (one line of an ultrasonic tomographic image) can be made one. Thus, the frame rate and the real-time property are improved, and the temperature elevation within a living body due to application of ultrasonic waves is checked.
(Twelfth Example Useful for Understanding the Invention)
FIG. 46 shows an arrangement of an ultrasonic therapeutic apparatus according to a twelfth example useful for understanding the invention. In this figure, like reference numerals are used to denote corresponding parts to those in FIGS. 1, 6, and 37. The ultrasonic diagnostic section 40 includes an RF circuit 51 for transmitting/receiving ultrasonic waves through the imaging probe 16, an image reconstruction section 52 for reconstructing a B-mode image of a patient from a received echo signal by the probe, an ultrasonic condition imaging section 53 for imaging the intensity distribution of ultrasonic waves from the received echo signal by the probe, and a display section 54 for displaying the B-mode image and the intensity distribution.
The operation of the present example will be described next. First, the plane section containing the diseased part 7 is scanned by ultrasonic waves emitted from the imaging probe 16, so that the diseased part appears on a B-mode image. At this point, treatment can be given in accordance with a plan for treatment which has been made in advance on the basis of the form of the diseased part that was measured by using CT or MRI. In this case, the operator is allowed to operate the apparatus in accordance with the contents of that plan displayed on a CRT that is prepared separately. Alternatively, the contents of that plan may be stored in the memory 45 in advance so that the system controller 9 can read them in sequence for subsequent treatment. In addition, a treatment plan making apparatus and an actual treatment room may be on-line connected to allow treatment based on a plan for treatment and fast amendment to the plan in the event of an unforeseen situation during treatment.
It is evident that the display of a treating region estimated on the basis of the intensity distribution is more useful to sure treatment than the focus 8 of therapeutic ultrasonic waves is displayed as it is. As a result of an experiment under the conditions that a therapeutic ultrasonic transducer is used that consists of a single piezoelectric element of 110mm in aperture diameter, 42mm in diameter of interal hole, 100mm in radius of curvature and 1.65MHz in resonance frequency, and the applied electric energy to that transducer is 400W, and the application time is 10sec., it has become evident that a treating region is shifted relative to the focus by about 2mm toward the ultrasonic transducer. Under such parameters, the treating region indicating marker is displayed shifted by 2mm from the focus 8 obtained in the intensity distribution imaging to the side of the applicator 1.
(Thirteenth Example Useful for Understanding the Invention)
FIG. 49 shows an arrangement of an ultrasonic therapeutic apparatus according to a thirteenth example useful for understanding the invention. In this figure, like reference numerals are used to denote corresponding parts to those in FIGS. 1, 6, 37, and 46 and description thereof is omitted. In this embodiment, the distortion of the intensity distribution is corrected by adjusting the timing of ultrasonic pulses for imaging intensity distribution. A distribution correction section 62 is connected to a timing signal generator 180.
The applicator 1 is constructed from the therapeutic ultrasonic transducer 1 placed on a concave plane having a hole in its center and the imaging probe 16. Such a construction allows the focus region to be formed in a three-dimensional form that would be obtained by rotating the character "X" about its center line. In this case, a distribution form with no practical problem can be obtained by making positional corrections taking into consideration only points where ultrasonic waves are strong even if the spatial distortion at points where the ultrasonic waves are weak is sacrificed. That is, the distortion is corrected with each point on the character "X" being allowed for. To this end, as shown in FIGS. 50A and 50B, the amount of correction is converted from the dimension of distance to the dimension of time and the timing of ultrasonic pulses for imaging intensity distribution from the therapeutic ultrasonic transducer 2 is changed by ΔT. More specifically, the amount of positional displacement at the point of maximum intensity on the character "X" is divided by the sound velocity with each raster scan. The timing of intensity distribution imaging ultrasonic pulses is changed from the timing for the focus position by the result of the division, ΔT. When, in this case, there are multiple points on the "X" for some raster, the point closest to the focus is selected as the criterion.
First, the focus shift is performed to fit a treating region to the target position. Next, the intensity distribution is performed with reference to the application conditions determined by the simulation. After reconfirmation that sufficient energy has been applied to the focus and no strong reflector or absorber is present on the propagation paths of therapeutic ultrasonic waves, the process goes to the application of therapeutic ultrasonic waves. In this case, the application of therapeutic ultrasonic waves according to the cavitation suppressing application method as disclosed in Japanese Patent application No. 6 - 248480 could provide a reliable therapeutic result (thermally metamorphosed region). After the application of therapeutic ultrasonic waves, the intensity distribution imaging is performed again, which allows a determination of whether a thermally metamorphosed region has been obtained.
Next, a method of display will be described with reference to FIG. 51 illustrating an example of a display image. With therapy based on strong ultrasonic waves, it is desirable to cauterize tissues in sequence from the point farthest from the therapeutic ultrasonic transducer 2, i.e., from the bottom surface of a volume to be treated, as disclosed in Japanese Patent Application No. 6 - 246843. The reason is that when the acoustic characteristics of a tissue vary due to thermal metamorphosis, ultrasonic waves reflect from its boundary, and the thermally metamorphosed region absorbs the energy. Hence the energy of ultrasonic waves becomes difficult to reach regions behind the thermally metamorphosed region. Since a plane that undergoes treatment intersects a two-dimensional B-mode tomogram in this method, it is difficult to take it as an image for treatment.
An ultrasonic therapeutic apparatus comprising:
a therapeutic ultrasonic wave generating source (2) having resonant characteristics for a first fundamental frequency;
an ultrasonic probe (16) having resonant characteristics for a second fundamental frequency;
first driving means (14) for driving said therapeutic ultrasonic wave generating source with a first drive signal of said first fundamental frequency;
second driving means (12) for driving said ultrasonic probe with a drive signal of said second fundamental frequency to generate in vivo imaging ultrasonic waves;
receiving means (20) for receiving echoes of first ultrasonic waves generated by said therapeutic ultrasonic wave generating source and echoes of second ultrasonic waves generated by said ultrasonic probe through said ultrasonic probe; and
forming means (22) for forming at least one of an intensity distribution image of said therapeutic ultrasonic waves in a subject or a tomographic image in the subject on the basis of a received echo signal output from said receiving means;
characterized in that the ultrasonic probe additionally has resonant characteristics for the first fundamental frequency.
The apparatus according to claim 1, wherein said first driving means (14) with said drive signal of said first fundamental frequency outputs at least two types of waves, a high energy burst wave for therapy and a low energy pulse wave for intensity distribution imaging inside a subject.
The apparatus according to claim 1 characterized by further comprising extracting means (21) connected between said receiving means and said forming means for extracting echo components of said first ultrasonic waves and echo components of said second ultrasonic waves from said received echo signal.
The apparatus according to claim 3, characterized in that said extracting means (21) includes means for amplifying echo components of said first ultrasonic waves and echo components of said second ultrasonic waves individually.
EP19960302221 1995-03-31 1996-03-29 Ultrasound therapeutic apparatus Expired - Lifetime EP0734742B1 (en)
JP9747495 1995-03-31
JP97474/95 1995-03-31
JP203576/95 1995-08-09
JP20357695 1995-08-09
EP0734742A2 true EP0734742A2 (en) 1996-10-02
EP0734742A3 true EP0734742A3 (en) 1999-07-14
EP0734742B1 true EP0734742B1 (en) 2005-05-11
ID=26438638
EP19960302221 Expired - Lifetime EP0734742B1 (en) 1995-03-31 1996-03-29 Ultrasound therapeutic apparatus
US (5) US5984881A (en)
EP (1) EP0734742B1 (en)
DE (2) DE69634714D1 (en)
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