Thursday, October, 30 1997
4:30-5:30 pm
1200 EECS
Abstract -
A two-dimensional non-invasive temperature-change estimation
algorithm based on the analysis of diagnostic backscattered
ultrasonic
RF-data is presented in this talk.
The technique consists of first estimating the echo
time-shift map
due to the combined effects of thermal dependence of speed
of
sound and thermal expansion in tissue.
The estimated time-shift map is then processed in order to
provide an estimate of the two-dimensional temperature map.
An experimental system consisting of
a therapeutic ultrasound unit and an ultrasound imaging unit
was used
to demonstrate the capabilities of the proposed method
when estimating temperature profiles in phantom and in
vitro tissue heating experiments.
The system performance is quantitatively
characterized in terms of the accuracy, spatial resolution,
and
ripple present in the temperature estimates.
The ripple is shown to be a consequence of the
thermo-acoustic lens effect
resulting from local changes of the speed of sound in heated
regions. A spatial band-limited filter design approach is
adopted to control the tradeoff between the desired spatial
resolution and
the acceptable level of ripple in the temperature estimates.
Moreover, possible applications and some limitations of the
proposed technique are discussed.
Biosketch -
Please refer to the homepage
link above.