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THERMAL CONTROL OF LENS OF ULTRASOUND TRANSDUCERS

IP.com Disclosure Number: IPCOM000032712D
Publication Date: 2004-Nov-10
Document File: 3 page(s) / 17K

Publishing Venue

The IP.com Prior Art Database

Related People

Reza Mirzalou: INVENTOR [+3]

Related Documents

US005560362A: PATENT [+3]

Abstract

This invention relates to a device and method to remove the heat from the lens area of a transducer. This method allows for direct removal of heat from the lens of the transducer and can be used on transducers that have integrated sensor-based thermal cut off devices such as a thermocouple or thermistor. This ability to dissipate larger amount of heat allows for the design of more sensitive transducer.

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Our Docket No.: 2004J18358

Title: THERMAL CONTROL OF LENS OF ULTRASOUND TRANSDUCERS
Inventor(s): Reza Mirzalou, Nelson Oliver and Tim Petersen

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* Abstract:

This invention relates to a device and method to remove the heat from the lens area of a transducer. This method allows for direct removal of heat from the lens of the transducer and can be used on transducers that have integrated sensor-based thermal cut off devices such as a thermocouple or thermistor. This ability to dissipate larger amount of heat allows for the design of more sensitive transducer.

* Background Information:

Some present and more future ultrasound transducers generate more heat within the transducer than can be dissipated within acceptable temperature-rise guidelines, due to the trend toward increasing sensitivity, and complexity within the transducer handle. Presently the generated heat is removed by means of passive and in some instances active cooling methods. But the lens temperature must in all cases remain below 41°C, as prescribed by regulatory mandates.

One method of ensuring that the upper temperature limit of a transducer is never exceeded is to employ a closed-loop temperature control circuitry. Such circuitry may include a temperature- sensing device embedded inside the transducer's lens. The feedback from such a device may control the input energy to the transducer, which in turn controls its acoustic performance, with the ultimate goal of keeping the temperature of the patient-contact area of the transducer below the prescribed 41°C level.

In this invention, several cooling methods are proposed.

1) A re-sposable (multi use) phase change pouch or pad is placed between the transducer lens and the patient. The pouch/pad and its contents are designed to transmit ultrasound with minimal attenuation and scatter. Such acoustic design features ensure that the pouch will induce no interference with the clinical content of the exam. The thermal functionality of the pouch/pad is due to a phase change material incorporated within it that can absorb the heat from the lens of the transducer without increasing in temperature. That is, a constituent of the pad is a material that melts near 36°C, absorbing the transducer heat via its own heat of fusion. This phase-change heat-absorption method can be combined with other passive and active cooling methods of the transducer as desired. to maximize the combined heat- mitigating effect.

2) A disposable Thermochromic "Gel Pad" is placed between the transducer lens and the patient. The color change upon reaching the temperature limit will alert the operator to switch to a new pad.

3) A liquid cooled standoff is placed between the transducer's lens and the patient.

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Details:

1) In one realization, a pad that resembles a conventional ultrasound gel pad, and employed in the normal fashion, contains a wax that is chosen for its large latent heat of fusion and a melting point near 36°C. A cand...