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oai:www.ideals.illinois.edu:2142/69311 2023-07-11 col_2142_5131 col_2142_8888 com_2142_5130 com_2142_8887 com_2142_234

U of I Only 134 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1985. http://hdl.handle.net/2142/69311 (UMI)AAI8600124 Benkeser, Paul Joseph 2014-12-15T19:04:58Z 2014-12-15T19:04:58Z 10000-01-01 1985 1985 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. Made available in DSpace on 2014-12-15T19:04:58Z (GMT). No. of bitstreams: 1 8600124.pdf: 3801639 bytes, checksum: 2091e5b0e3fa121fcd2f9d026dc8e95d (MD5) Previous issue date: 1985 Embargo set by: Seth Robbins for item 69477 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Engineering, Biomedical Unfocused Multielement and Tapered Phased Array Ultrasound Transducers for Hyperthermia Treatment (Heat, Perfusion, Tumor, Phantom, Cancer) text Electrical Engineering Electrical Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.