Massachusetts Institute of Technology

Padmakar P Lele

Gerard E Sleefe

Kenneth D Rolt

An ultrasound hyperthermia applicator suitable for medical hyperthermia treatment, and method for using the same, includes two ultrasound sources producing focused ultrasound beams of frequencies f.sub.0 and f.sub.1. An aiming device directs the two ultrasound beams so that they cross each other confocally at the target. A controller activates the two ultrasound sources so that the target is simultaneously irradiated by the two focused ultrasound beams. The two ultrasound sources provide acoustic energy sufficient to cause significant intermodulation products to be produced at the target due to the interaction of the two ultrasound beams. The intermodulation products are absorbed by the target to enhance heating of the target. In preferred embodiments the ultrasound sources include pair of signal generator for producing gated ultrasound output signals driving single crystal ultrasound transducers. In other embodiments the ultrasound sources include a pair of phased array ultrasound transducers for generating two steerable ultrasound beams. An aiming device is provided for electronically steering and focusing the two ultrasound beams so that they cross each other confocally at the target. Further embodiments employ pluralities of transducers, arrays, or both.

Apparatus and method for acoustic heat generation and hyperthermia

A multi-function probe for use in hyperthermia therapy employs at least one pair of temperature sensors, which may be thermocouples or thermistors. One sensor of the pair includes an exposed electrode which directly measures tissue temperature. The other sensor includes an electrode covered by a material having a known ultrasound absorption coefficient, for measuring the local intensity of ultrasonic energy. By comparing these two measurements, an ultrasound or other hyperthermia energy absorption coefficient of the tissue in the target region can be determined. A plurality of these paired sensors can be utilized to yield a measurement of thermal diffusion. The probe can also include one or more piezoelectric receiver elements, for providing accurate source-to-target registration.

Multi-purpose temperature sensing probe for hyperthermia therapy

A therapeutic ultrasound hyperthermia system utilizes a phased array of ultrasound transducer elements. By varying the phase delays in the excitation of individual transducer elements, the focal depth of the ultrasonic beam can be varied, without changing the distance between the transducer and the patient. The phased array of transducer elements can be an array of rectangular elements which are rotated about an axis to deliver ultrasound to the target region while minimizing overall heating effect in the treatment areas outside the target region.

Electronically-controlled variable focus ultrasound hyperthermia system

A therapeutic hyperthermia system generates a line-focus beam of ultrasound which can be mechanically scanned across a treatment volume of tissue. The ultilization of a line-focus advantageously reduces the peak intensity of the ultrasonic beam. The system includes methods of scanning the line-focus beam to provide optimal treatment protocols for deep tumors and other pathological conditions while minimizing damage in overlying body tissues. The utilization of mechanical scanning reduces the number of transducers, amplifiers and associated electronics required.

Mechanically scanned line-focus ultrasound hyperthermia system

A system for delivering ultrasound hyperthermic therapy to a subject includes a plurality of piezoelectric ultrasound transducer elements arranged in a two-dimensional array to provide multiple sources of ultrasonic energy, and variable activation elements for activating the transducer elements individually and at variable electrical energy levels. A plurality of lens elements is provided for transmitting the multiple sources of ultrasonic energy to the subject, in conjunction with focusing elements which individually vary the attitude of the lens elements to change the focal regions of the individual lenses. The transducer elements and lens elements can be corresponding 'pie-slice' sectors arranged in a circular array, in combination with a central circular transducer and lens.

Diffuse focus ultrasound hyperthermia system

Methods and devices for characterizing tissues and the like utilize signals obtained from ultrasonic backscatter processes. The method accounts for frequency-dependent attenuation, spatially-varying media statistics, arbitrary beam geometries, and arbitrary pulse shapes. Statistical analysis is employed to estimate the scatterer number density (SND) of tissues. The method for estimating the scatterer number density incorporates measurements of both the statistical moments of the backscattered signals and the point spread function of the acoustic system.

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Winchester, MA, United States of America

Padmakar P Lele