Proceedings Article | 13 February 2007
Proc. SPIE. 6437, Photons Plus Ultrasound: Imaging and Sensing 2007: The Eighth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics
KEYWORDS: Breast, Data modeling, Tumors, Tissues, Distortion, Tomography, Transducers, Photoacoustic tomography, Acquisition tracking and pointing, Acoustics
In this paper, we present new Adaptive and Robust Techniques (ART) for microwave-based thermoacoustic
tomography (TAT) and laser-based photo-acoustic tomography (PAT), and study their performances for breast
cancer detection. TAT and PAT are emerging medical imaging techniques that combine the merits of high
contrast due to electromagnetic or laser stimulation and high resolution offered by thermal acoustic imaging.
The current image reconstruction methods used for TAT and PAT, such as the widely used Delay-and-Sum
(DAS) approach, are data-independent and suffer from low resolution, high sidelobe levels, and poor interference
rejection capabilities. The data-adaptive ART can have much better resolution and much better interference
rejection capabilities than their data-independent counterparts. By allowing certain uncertainties, ART can
be used to mitigate the amplitude and phase distortion problems encountered in TAT and PAT. Specifically,
in the first step of ART, RCB is used for waveform estimation by treating the amplitude distortion with an
uncertainty parameter. In the second step of ART, a simple yet effective peak searching method is used for phase
distortion correction. Compared with other energy or amplitude based response intensity estimation methods,
peak searching can be used to improve image quality with little additional computational costs. Moreover, since
the acoustic pulse is usually bipolar: a positive peak, corresponding to the compression pulse, and a negative
peak, corresponding to the rarefaction pulse, we can further enhance the image contrast in TAT or PAT by using
the peak-to-peak difference as the response intensity for a focal point. The excellent performance of ART is
demonstrated using both simulated and experimentally measured data.
