Photoacoustic tomography (PAT), as well as thermoacoustic tomography (TAT),
utilize electromagnetic radiation in its visible, near infrared, microwave, and
radiofrequency forms, respectively, to induce acoustic waves in biological tissues for
imaging purposes. Combining the advantages of both the high image contrast that results
from electromagnetic absorption and the high resolution of ultrasound imaging, these
new imaging modalities could be the next successful imaging techniques in biomedical
applications. Basic research on PAT and TAT, and the relevant physics, is presented in
Chapter I. In Chapter II, we investigate the imaging mechanisms of TAT in terms of
signal generation, propagation and detection. We present a theoretical analysis as well as
simulations of such imaging characteristics as contrast and resolution, accompanied by
experimental results from phantom and tissue samples. In Chapter III, we discuss the
further application of TAT to the imaging of biological tissues. The microwave
absorption difference in normal and cancerous breast tissues, as well as its influence on
thermoacoustic wave generation and the resulting transducer response, is investigated
over a wide range of electromagnetic frequencies and depths of tumor locations. In
Chapter IV, we describe the mechanism of PAT and the algorithm used for image
reconstruction. Because of the broad bandwidth of the laser-induced ultrasonic waves and
the limited bandwidth of the single transducer, multiple ultrasonic transducers, each with
a different central frequency, are employed for simultaneous detection. Chapter V further
demonstrates PATÂs ability to image vascular structures in biological tissue based on
bloodÂs strong light absorption capability. The photoacoustic images of rat brain tumors
in this study clearly reveal the angiogenesis that is associated with tumors. In Chapter
VI, we report on further developing PAT to image deeply embedded optical
heterogeneity in biological tissues. The improved imaging ability is attributed to better
penetration by NIR light, the use of the optical contrast agent ICG (indocyanine green)
and a new detection scheme of a circular scanning configuration. Deep penetrating PAT,
which is based on a tissueÂs intrinsic contrast using laser light of 532 nm green light and
1.06 µm near infrared light, is also presented.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/3181 |
| Date | 12 April 2006 |
| Creators | Ku, Geng |
| Contributors | Wang, Lihong V. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | 3052679 bytes, electronic, application/pdf, born digital |
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