General Electric Company

Axel F Brisken

Lowell Scott Smith

Michael S Horner

Ronald C Carnes

Ted F Naumann, Jr

Claudio I Zanelli

Wing Law

Wayne Barbour

An ultrasonic transducer assembly includes noise suppressing backing material for the transducer comprising a composite of a matrix material and particles of an attenuating soft material such as rubber, epoxy, and plastic. The particle size is preferably selected by sieving the particles through a sieve of grid size 30 to 80. In preferred embodiments the particles of attenuating soft material are filled with particles of heavy oxides, metal powders, or other density lowering fillers. The ratio of matrix material to filler particles determines mechanical strength and attenuation of the composite material. Attenuation coefficient and size of the filler particles determines the attenuation of the composite material.

Ultrasonic transducer and attenuating material for use therein

An ultrasound probe for positioning in the vaginal cavity includes a phased array of transducer elements at one end thereof oriented at an acute angle with respect to the central axis of the probe whereby the imaging field of view is provided by rotating the probe. A biopsy needle assembly snaps onto slots on the probe with a fork and socket fit. A handle on the probe is offset from the central axis of the probe thereby freeing the space around the entrance to the needle guide and facilitating the manipulation by hand of a needle in the guide.

Intracavitary ultrasound and biopsy probe for transvaginal imaging

An array of transducer elements which can be selectively actuated as a linear array for sector scanning and selectively actuated as a plurality of concentric annular arrays for focused Doppler blood flow measurements.

Transducer array for sector scan and doppler flow measurement

An improved material for an ultrasonic transducer assembly having improved noise suppression characteristics comprising an ultrasonic transducer having a plurality of surfaces, a housing for receiving said transducer whereby one surface of said transducer is free to transmit and receive ultrasonic waves, and a material positioned about said transducer and between said transducer and the environment or housing for attenuating ultrasonic energy, said material comprising a heavily loaded resin based on an unfilled low viscosity potting gel and a filler selected from the group consisting of heavy oxides, metal powders, and density lowering fillers. In specific embodiments lead oxide, tungsten powder, and glass microspheres have been used as the filler in a silicone or flexible epoxy.

The radiation pattern of shaded single element piezoelectric transducers and transducer arrays has reduced side lobe levels. Shading to reduce the intensity of emitted ultrasound at the edges of the transducer relative to the center is realized by varying the electric/acoustic conversion efficiency or polarization of the piezoelectric material, by having different mechanical element lengths, by selectively poling the piezoelectric material to produce poled and unpoled regions, and by control of electrode geometry. The shading of a phased array ultrasonic transducer is described in both lateral dimensions.

Ultrasonic transducer shading

The ultrasonographer changes the frequency of ultrasound pulses emitted from an ultrasonic transducer as a result of adjusting the RF frequency of the transmitter burst exciting the broadband transducer; this adjustment takes place between pulse transmissions, while examining the patient. In a phased array imager utilizing baseband processing of received echo signals, the same adjustment supplies the corresponding frequency to the demodulator circuits. An alternative method of changing the system spectrum is to have a narrow bandwidth receiver whose center frequency is varied over the available bandwidth.

Variable frequency ultrasonic system

A linear array for rectilinear and sector scan imaging has identical approximately diamond-shaped transducer elements fabricated by making two pairs of straight line cuts at small angles through a piezoelectric slab. The Y-axis radiation pattern (parallel to element length and perpendicular to the array length) has lower side lobe levels than equal sized rectangular elements. No changes in the imager electronics among channels is required, and the shading function may be modified by changing only the transducer.

Ultrasonic transducer array shading

An ultrasonic sector scanner using rotating transducers includes a transducer support wheel having a circumferential rim surface with a plurality of recessed seats within the circumferential surface for receiving inwardly facing transducers. The wheel and recessed seats provide accurate alignment of the transducers and acoustic mirrors direct ultrasonic energy between the transducers and ports.

Ultrasonic sector scanner utilizing rotating transducer

An ultrasonic transducer has two impedance matching layers bonded to the transducer element which have different thicknesses and are 90.degree.-100.degree. and 35.degree.-55.degree. matching layers. This structure has a high sensitivity comparable to a broadband front surface matched transducer with quarter wavelength (90.degree. and 90.degree.) matching layers, and has primarily a single resonant mode so as to be suitable for relatively narrow band applications.

Ultrasonic transducer for single frequency applications

A slab of piezoelectric ceramic plated on all surfaces is bonded to quarter wavelength impedance matching layers of glass and plastic. The top surface of the ceramic is slotted and parallel cuts orthogonal to the slots are made through the ceramic and into the glass to delineate an array of elements each with a signal electrode between slots and a wrap-around ground electrode. After making ground connections and flying lead connections to the signal electrodes, the matching layers are fully cut through from the front. A covering or wear plate is attached to the front surface and a relatively large mass of acoustic damping material covers the backs of the elements.

Fabrication of front surface matched ultrasonic transducer array

An ultrasonic transducer array with high sensitivity, for use in water tanks and with human subjects in steered beam imagers to make wide angle sector scans, has narrow transducer elements and one or more quarter-wavelength impedance matching layers on the front surface of each element. The matching layers as well as the piezoelectric ceramic are completely cut thorugh and guide acoustic energy incident at any angle to the ceramic. A continuous covering or wear plate is attached to the matching layers and a continuous damping material can cover the backs of the elements.

Front surface matched piezoelectric ultrasonic transducer array with

A linear transducer array for 90.degree. or other wide angle sector scans is covered by a body contacting wear plate made of a material such as filled silicone rubber or polyurethane epoxy in which the longitudinal sound velocity is equal to or less than that in the body and in which the acoustic impedance for longitudinal sound waves is approximately equal to that of the body. Refraction, if it occurs, enhances the field of view without reducing the transmission of acoustic energy. The wear plate provides mechanical support for a fragile front surface matched array.

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Shingle Springs, CA, United States of America

Axel F Brisken