Title :
Variable frequency field conjugate lenses for ultrasound hyperthermia
Author :
Lalonde, Ron ; Hunt, John W.
Author_Institution :
Dept. of Med. Phys., Hamilton Regional Cancer Centre, Ont., Canada
Abstract :
This paper describes variable frequency focusing with field conjugate lenses designed to mimic the multiple-focusing capabilities of large two-dimensional phased arrays. Simulations, experiments, and Fresnel diffraction analysis are used to show that both the size and the depth of a field conjugate lens focus may vary with frequency. Examples are given for field conjugate lens focusing with planar transducers, focused transducers, and ordinary refracting lenses.<>
Keywords :
biomedical ultrasonics; hyperthermia; lenses; radiation therapy; ultrasonic diffraction; ultrasonic focusing; Fresnel diffraction analysis; field conjugate lens focus; focused transducers; large two-dimensional phased arrays; multiple-focusing capabilities; ordinary refracting lenses; planar transducers; simulations; ultrasound hyperthermia; variable frequency field conjugate lenses; variable frequency focusing; Acoustic transducers; Biomedical transducers; Frequency; Hyperthermia; Lenses; Medical treatment; Optical design; Phased arrays; Ultrasonic imaging; Ultrasonic transducers;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
