Dennis Healy
Research Interests
Applied Mathematics, Signal Processing, Medical Imaging, and Nonlinear Optics
A Few Recent Publications
Reduced Motion Artifacts in Medical
Imaging by Adaptive Spatio-Temporal Reconstruction
In this paper we introduce an algorithm for imaging a time varying
object f(\vec{x},t), from its projections at different fixed times.
This algorithm differs from other algorithms in that we do not need the
object to remain stationary during the data
acquisition period. We show that the reconstruction of coarse features,
corresponding to low spatial-frequency data,
can be made
nearly instantaneously in time from the evolving data. A temporal sequence of
these low spatial-frequency
reconstructions can be used to estimate the motion of the object.
Once the motion is estimated, we may use the estimate to compensate for
some of the motion of fine scale features. This enables accurate reconstructions
of the time varying fine structure in several cases.
The algorithm is demonstrated for a selection of phantoms and actual MRI
studies. In general,
this technique shows promise for a wide variety of applications in MRI,
as well as for heart imaging using x-ray CT.
Clinical applications should include both functional MRI such as
dynamic imaging of oxygen usage and blood flow in the brain, and
motion imaging of joints, angiography in the lungs, and heart imaging.
Applications of time-frequency bases to multiple access fiber optic communication systems
In this paper we present background material concerning the propagation of pulses through fiber optics, and current transmission
schemes in fiber optics.
We discuss the value of using different signal processing techniques, and time-frequency bases in Fiber Optic Transmission. Finally we will outline methods which allow
one to send optical pulses with arbitrary shapes through fiber optics.
GRADUATE STUDENT SUPERVISION
- Joseph DeStefano: PhD Computer Science, Dartmouth College. June 1993
Dissertation: Efficient Velocity Estimation in Doppler Ultrasound Imaging
- Jian Lu: PhD, Thayer School of Engineering, Dartmouth College. June 1993
Dissertation: Signal Recovery and Noise Reduction with Wavelets
- Sean Moore: PhD, Computer Science, Dartmouth College. June 1994
Dissertation:
Efficient Stabilization Methods for Fast Polynomial Transforms.
- Harry Chen PhD student, Mathematics, Dartmouth College.
- Doug Warner PhD student, Mathematics, Dartmouth College.
- Sumit Chawla PhD student, Computer Science, Dartmouth College.
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