CN103341241A - High-strength focusing ultrasonic energy converter array - Google Patents

Abstract

The invention discloses a high-intensity focused ultrasonic transducer array, which includes a spherical crown-shaped rigid support frame and several ultrasonic transducers, one ultrasonic transducer is placed separately in the center of the spherical crown-shaped rigid support frame, and the remaining ultrasonic transducers The transducers are discretely distributed on several layers of concentric rings with the ultrasonic transducer as the center, and the angular spacing between the ring layers is not equal. The interval between the ring layers and the distance between adjacent ultrasonic transducers in the same ring The spacing is within 5mm, and the position of the initial ultrasonic transducer of each layer of concentric rings is randomly determined. Each ultrasonic transducer has an independent electrical excitation signal feeder, which is connected to the phase-controlled signal excitation system. The invention calculates the phase and voltage amplitude distribution of the ultrasonic transducer through the focus mode synthesis method based on the pseudo-inverse matrix theory, realizes the electronic focusing and scanning of the sound beam, and generates the required single-focus or multi-focus sound field control modes, which are applied in the human body Rapid thermal ablation of targeted tumor lesions.

Description

A high-intensity focused ultrasound transducer array

technical field

The invention relates to the field of ultrasonic vibration high-intensity sound field output using the inverse piezoelectric effect, in particular to a high-intensity focused ultrasound transducer array applied to high-intensity focused ultrasound tumor treatment.

Background technique

With the development of ultrasonic technology, the application of high-power sound waves in the air is becoming more and more extensive. In the fields of biomedical engineering, ultrasonic medical technology, etc., in order to obtain higher-intensity sound fields, curved surfaces have self-focusing, acoustic lens focusing, multi-element array self-focusing, and phased array focusing. These types of high-intensity sound fields Acquisition methods are used in many production fields and can basically meet the needs of production applications, but there are also some shortcomings. Curved surfaces have self-focusing and acoustic lens focusing methods. The conversion rate of ultrasonic energy is low and the power of focused sound is small, especially for curved surfaces. Self-focusing also has problems such as high processing difficulty and high cost. Although multi-element array self-focusing and phased array focusing have large focused acoustic power, they also have low ultrasonic energy conversion rate, high power consumption, large volume, and inconvenient movement. question.

High-intensity focused ultrasound phased array is one of the key components of phased high-intensity focused ultrasound tumor therapy system. By adjusting the excitation phase and amplitude of any of the array elements, it is possible to achieve in vitro ultrasound converging on one or more focal points in the human body, forming a high-intensity sound field area in the target area, and then making the abnormal tissue cells at the focal point in a short time The temperature rises rapidly (the temperature reaches above 65°C within 5 to 10 seconds), resulting in coagulation necrosis, while the normal tissue outside the focus has only a small amount of energy deposition and little damage. However, in the actual operation process, if the distance between the ultrasonic energy units is large and the spatial distribution is not compact enough, large side lobes are likely to be generated during electronic focusing and scanning, which may cause excessive heating of normal tissues outside the target area. Harm the normal tissue health of the patient.

In order to overcome the shortcomings of the above high-intensity sound field acquisition technology, the patent document with the publication number CN1775327 discloses a high-intensity focused ultrasonic spherical phased array in which the array elements are densely distributed in a ring. The phased array consists of a large-aperture rigid spherical crown It is composed of several discretely distributed array elements. The central circular hole of the spherical crown provides installation space for the detection probe of the ultrasonic positioning device. All array elements are discretely distributed on several layers of concentric rings with the center of the spherical crown as the origin. The angular spacing between the ring layers is equal, the initial array element position of each layer of concentric rings is randomly determined, and the rest of the array elements are evenly distributed on the concentric rings at equal angular intervals, and each array element has an independent electrical excitation The signal feeders are respectively connected to the phase control signal excitation system. "In this phased array, because the detection probe of the ultrasonic positioning device is installed in the central circular hole of the spherical crown, the focus energy is not concentrated when the sound beam is focused on the axis, and the focus point position is offset by the distance of the sound beam axis (ie Focus scanning range) is limited, which affects the treatment range of the transducer; in addition, each array element division adopts the same angular spacing between the ring layers, resulting in that the adjacent array element ring spacing of the inner ring layer is smaller than that of the outer ring layer. The distance between adjacent array element rings is large, and the side lobes generated during focusing of the phased array are larger than those of the phased array with densely arranged array elements under the same conditions, which affects the focusing effect.

Contents of the invention

In order to overcome the deficiencies of the above-mentioned prior art, the object of the present invention is to provide a high-intensity focused ultrasound transducer array with a sandwich-type ultrasonic transducer, which is used in an MRI-guided phase-controlled high-intensity focused ultrasound system. The invention includes a spherical crown-shaped rigid support frame and several ultrasonic transducers connected to the spherical crown-shaped rigid support frame.

The ultrasonic transducer includes a bolt, a rear cover plate, a piezoelectric ceramic sheet, an electrode sheet, a horn, a conversion sleeve, a vibrating plate and a coupling layer bonded on the vibrating plate. The back cover and the horn connect and clamp the back cover, the piezoelectric ceramic sheet, the electrode piece and the horn that are sequentially sleeved on the bolts through bolts, forming the energy conversion part of the ultrasonic transducer array, which will excite The excitation power signal output by the power supply is converted into the ultrasonic vibration energy at the front end of the horn of the ultrasonic transducer. In addition, the horn is provided with a flange for connecting with the spherical crown type rigid support frame. The conversion sleeve is set on the front end of the horn by welding or screw connection, or the conversion sleeve and the horn are manufactured as an integral part, the vibration plate is set on the front end of the conversion sleeve by welding or bonding, and the coupling layer is glued on The material of the front end of the vibrating plate and the coupling layer is foam plastic or epoxy resin. The longitudinal vibration generated by the energy conversion part is transferred to the vibration plate through the conversion sleeve and then converted into the bending vibration of the vibration plate and the coupling layer. Bending vibration is one of the most easily coupled and transmitted ultrasonic vibration forms with air, which is beneficial to the ultrasonic vibration energy from the vibration The transmission from the plate to the air, and the coupling layer pasted on the front end of the vibrating plate improves the transmission coefficient of ultrasonic vibration energy from the vibrating plate to the air, which is more conducive to the realization of a high-intensity sound field in front of the vibrating plate. The natural frequency of the bending vibration of the vibrating plate and the coupling layer is consistent with the natural frequency of the longitudinal vibration of the ultrasonic transducer. When the electrode sheet of the ultrasonic transducer is connected to the electrical signal of the excitation power supply, the ultrasonic transducer works at its natural frequency. The transducer system forms a resonance, and the amplitude of the bending vibration of the vibration plate and the coupling layer reaches a maximum.

There are several holes for installing ultrasonic transducers on the spherical crown-shaped rigid support frame. The curvature radius of the spherical crown-shaped rigid support frame is R=L1+L2+L3, where L1 is the minimum focusing depth of the phased array, and L2 is the axial scanning range of the phased array, L3 is the distance between the coupling layer in the ultrasonic transducer and the fixed flange, and the f value of the spherical crown rigid support frame satisfies 0.70≤f value≤0.85, where the f value It is the ratio of the radius of curvature R of the spherical cap of the rigid support frame to the diameter D of the bottom of the spherical cap.

An ultrasonic transducer is placed separately in the center of the spherical crown-shaped rigid support frame, and the rest of the ultrasonic transducers are discretely distributed on several concentric rings centered on the ultrasonic transducer, and the angular spacing between the ring layers is not equal , the angular spacing is centered on the ultrasonic transducer in the center of the spherical crown-shaped rigid support frame, the angle between two ultrasonic transducers in the same ring layer, the interval between each ring layer and the adjacent ultrasonic transducers in the same ring. The distance between the transducers is within 5mm. The position of the initial ultrasonic transducer of each layer of concentric rings is randomly determined. There are independent electric excitation signal feeders, respectively connected to the phase control signal excitation system. The working frequency of all ultrasonic transducers and the excitation power signal frequency of all ultrasonic transducers are the same, each excitation power signal is independently controllable, and the phase and voltage amplitude are different, calculated by the focal mode synthesis method based on pseudo-inverse matrix theory The phase and voltage amplitude combination of the ultrasonic transducer, the ultrasonic transducer is excited by the excitation power signal, and the radiated sound waves are superimposed in the three-dimensional space, which will change the curvature and center position of the sound wave front and realize the electronic focusing of the sound beam And scan to generate the required single-focus or multi-focus sound field control mode, which is applied to the rapid heating and ablation of target tumor lesions in the human body.

Compared with the high-intensity focused ultrasound spherical phased array in which the array elements are densely distributed in a ring, the ultrasonic transducer in the high-intensity focused ultrasound transducer array adopts a sandwich structure, which has a large power capacity and high ultrasonic vibration energy conversion rate. The advantage of high sound field output intensity is that it can heat and ablate the tumor lesions in the patient for a short time, which reduces the patient's surgical pain. In addition, it has novel and simple structure, small overall volume, convenient movement, large scanning range and low processing difficulty. , low production cost, long service life and other advantages are conducive to its industrial development and broad application prospects.

Description of drawings

Fig. 1 is a schematic structural view of the present invention.

Fig. 2 is a schematic structural view of a spherical crown-shaped rigid support frame of the present invention.

Fig. 3 is a schematic structural diagram of the ultrasonic transducer in the present invention.

Explanation of symbols in the figure: 1. Spherical crown type rigid support frame, 2. Ultrasonic transducer, 3. Bolt, 4. Rear cover, 5. Piezoelectric ceramic sheet, 6. Electrode sheet, 7. Horn, 8 .Flange plate, 9. Conversion sleeve, 10. Vibration plate, 11. Coupling layer.

Detailed ways

Example 1

As shown in FIGS. 1-3 , a high-intensity focused ultrasound transducer array includes a spherical crown-shaped rigid support frame 1 and 37 sandwich-type ultrasonic transducers 2 connected to the spherical crown-shaped rigid support frame 1 . Each ultrasonic transducer 2 includes a bolt 3, a rear cover plate 4, a piezoelectric ceramic sheet 5, an electrode sheet 6, a horn 7, a conversion sleeve 9, a vibrating plate 10 and a coupling bonded on the vibrating plate 10. Layer 11. The rear cover 4 and the horn 7 connect and clamp the rear cover 4, the piezoelectric ceramic sheet 5, the electrode sheet 6 and the horn 7, which are successively sleeved on the bolt 3, through the bolt 3, forming an ultrasonic transducer 2 for the energy conversion part. The conversion sleeve 9 is arranged on the front end of the horn 7 through screw connection, the vibration plate 10 is arranged on the front end of the conversion sleeve 9 by welding, and the coupling layer 11 is glued on the front end of the vibration plate 10, and the material of the coupling layer 11 is epoxy resin. The diameter of ultrasonic transducer 2 piezoelectric ceramic section is 12mm, the material of piezoelectric ceramic piece 5 is PZT-8, the size is: Ф12×Ф5×3mm, the diameter of 7 sections of horn is 7mm, the outer diameter of the large end of conversion sleeve 9 is 14mm, The inner diameter of the large end is 10mm, the natural frequency of the transducer is 40.5KHz, the impedance is 43 ohms, and the dynamic resistance is 16.5 ohms.

The radius of curvature of the spherical crown-shaped rigid support frame 1 is R=L1+L2+L3, wherein L1 is the minimum focusing depth of the phased array, L2 is the axial scanning range of the phased array, and the spherical crown-shaped rigid support frame 1 The f value satisfies 0.70≤f value≤0.85, where f is the ratio of the curvature radius R of the spherical crown-shaped rigid support frame 1 to the diameter D of the spherical crown bottom, and L3 is the coupling layer 11 to the fixed flange in the ultrasonic transducer 2 The distance between 8.

Use screws to connect the ultrasonic transducer 2 and the spherical crown-shaped rigid support frame 1 together through the flange 8 on the horn 7. An ultrasonic transducer 2 is placed separately in the center of the spherical crown-shaped rigid support frame 1, and the rest Ultrasonic transducers 2 are discretely distributed on 4 layers of concentric rings with the ultrasonic transducer 2 as the center, the first layer of ultrasonic transducers 2 as the center, the angular distance is 0°; the second layer has 6 ultrasonic transducers Transducers 2 with an angular spacing of 60°; the third layer has 12 ultrasonic transducers 2 with an angular spacing of 30°; the fourth layer has 18 transducers with an angular spacing of 20°.

In an embodiment of the present invention, the minimum focusing depth of the array is L1=3.5cm, the axial scanning range L2=3.2cm, and the distance L3=2.5 between the coupling layer 11 of the ultrasonic transducer 2 and the fixed flange 8 cm, so the radius of curvature R=L1+L2+L3=9.2cm of the spherical crown-shaped rigid support frame 1, the f value of the spherical crown-shaped rigid support frame 1 is taken as 0.8, and the diameter of the bottom of the spherical crown D=11.5cm.

Each ultrasonic transducer 2 has an independent electrical excitation signal feeder, which is respectively connected to the phase control signal excitation system. The operating frequency of all ultrasonic transducers 2 and the frequency of excitation power signals of all ultrasonic transducers 2 are the same, and each excitation power signal is independently controllable, with different phases and voltage amplitudes, through focal mode synthesis based on pseudo-inverse matrix theory The method calculates the combination of phase and voltage amplitude of each ultrasonic transducer 2, and the sound waves radiated by the ultrasonic transducer 2 are superimposed in three-dimensional space after being excited by the excitation power supply, so that the curvature and center position of the sound wave front change, and the sound beam is realized. The electronic focusing and scanning can produce the required single-focus or multi-focus sound field control mode, which is applied to the rapid heating and ablation of target tumor lesions in the human body.

Claims (10)

1. A high-intensity focused ultrasonic transducer array is characterized in that: it comprises a spherical crown type rigid support frame and several ultrasonic transducers, and the spherical crown type rigid support frame is provided with several ultrasonic transducers for installation hole; the ultrasonic transducer includes bolts, back cover, piezoelectric ceramic sheet, electrode piece, horn, conversion sleeve, vibration plate and coupling layer bonded on the vibration plate, back cover and horn The rear cover plate, piezoelectric ceramic sheet, electrode sheet and horn that are sequentially sleeved on the bolt are connected and clamped by bolts, the conversion sleeve is set at the front end of the horn, the vibration plate and the The coupling layer is set at the front end of the conversion sleeve; an ultrasonic transducer is placed separately in the center of the spherical crown-shaped rigid support frame, and the rest of the ultrasonic transducers are discretely distributed on several layers of concentric rings centered on the ultrasonic transducer. The angular spacing between the ring layers is not equal. The interval between each ring layer and the distance between adjacent ultrasonic transducers in the same ring are within 5mm. The initial ultrasonic transducer position of each concentric ring is randomly determined. The rest of the ultrasonic transducers are closely and evenly distributed on the concentric rings successively at equiangular intervals, and each ultrasonic transducer has an independent electric excitation signal feeder, which is connected to the phase control signal excitation system respectively. 2. The high-intensity focused ultrasound transducer array according to claim 1, characterized in that: the radius of curvature R=L1+L2+L3 of the spherical crown type rigid support frame, wherein L1 is the phased array The minimum depth of focus, L2 is the axial scanning range of the phased array, L3 is the distance between the coupling layer in the ultrasonic transducer and the fixed flange, and the f value of the spherical crown rigid support frame satisfies 0.70≤f value≤ 0.85, where f is the ratio of the radius of curvature R of the spherical cap of the rigid support frame to the diameter D of the bottom of the spherical cap. 3. The high-intensity focused ultrasonic transducer array according to claim 1, characterized in that: the operating frequency of all ultrasonic transducers is the same as the excitation power signal frequency of all ultrasonic transducers, and each excitation power signal can be independently controlled. The phase and voltage amplitude are different, and the combination of the phase and voltage amplitude of the array element is calculated by the focus mode synthesis method based on the pseudo-inverse matrix theory, so as to realize the electronic focusing and scanning of the sound beam, and generate the required single-focus or multi-focus sound field control mode. 4. The high-intensity focused ultrasonic transducer array according to claims 1-3, characterized in that: the conversion sleeve and the horn of the ultrasonic transducer are manufactured as an integral part. 5. The high-intensity focused ultrasonic transducer array according to claims 1-3, characterized in that: the conversion sleeve of the ultrasonic transducer is welded to the front end of the horn. 6. The high-intensity focused ultrasonic transducer array according to claims 1-3, characterized in that: the conversion sleeve of the ultrasonic transducer is threadedly connected to the front end of the horn. 7. The high-intensity focused ultrasound transducer array according to claims 1-3, characterized in that: the vibration plate of the ultrasonic transducer is bonded to the front end of the conversion sleeve. 8. The high-intensity focused ultrasound transducer array according to claims 1-3, characterized in that: the vibration plate of the ultrasonic transducer is welded to the front end of the conversion sleeve. 9. The high-intensity focused ultrasound transducer array according to claims 1-3, characterized in that: the material of the coupling layer of the ultrasound transducer is foam plastic. 10. The high-intensity focused ultrasound transducer array according to claims 1-3, characterized in that: the material of the coupling layer of the ultrasound transducer is epoxy resin.

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