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|Title:||Unfocused Multielement and Tapered Phased Array Ultrasound Transducers for Hyperthermia Treatment (Heat, Perfusion, Tumor, Phantom, Cancer)|
|Author(s):||Benkeser, Paul Joseph|
|Department / Program:||Electrical Engineering|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||Currently used ultrasound clinical hyperthermia systems lack adequate control of the energy deposition used to heat tumors. This thesis discusses the development and testing of two different ultrasound hyperthermia transducers which allow improved control of the energy deposition.
An unfocused multielement transducer was developed to treat superficial tumors. The acoustical power outputs of the elements can be adjusted independently to control the temperature in the tumor and normal tissues. Acoustical power output measurements and temperature data from exposures of tissues in vitro indicated that the transducer is capable of providing intensities seven times greater than those required to produce therapeutic temperatures.
Two ultrasonic tapered phased array transducers were developed to study the feasability of using such transducers to treat deep seated tumors. A tapered phased array transducer consists of a linear phased array employing elements with a tapered thickness. The cylindrical focal region is generated and steered in two dimensions by controlling the phases of the driving signals on each element, and moved in the third dimension by controlling the driving frquency. A theoretical model of the field intensity distribution of a tapered phased array was developed which agreed well with the experimentally obtained data. Acoustical power output measurements indicated that tapered phased arrays are capable of providing the intensities necessary for producing therapeutic temperatures in tumors. However, an analysis of the intensity gain produced by a tapered phased array indicated that it could severely limit the size of tumors that can be preferentially heated.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985.
|Date Available in IDEALS:||2014-12-15|
This item appears in the following Collection(s)
Dissertations and Theses - Electrical and Computer Engineering
Dissertations and Theses in Electrical and Computer Engineering
Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois