Mathematics and Physics of Emerging Biomedical Imaging (1996) / Chapter Skim
Currently Skimming:
11 MEDICAL OPTICAL IMAGING
11 MEDICAL OPTICAL IMAGING
Pages 157-166
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 157... ...
As these substances play crucial roles in metabolic processes at the cell level, the ability to discern them through indirect measurements would have important medical implications.
|
From page 158... ...
~ ~ .2 Data Acquisition Strategies Objects have been illuminated for medical imaging by the continuous beam, time-resolved beam, and phase-modulated beam methods. The last method has the advantage of allowing measurement of the mean optical pathIength without the size and cost problems associated with ultrashort light pulses and a fast optical detector.
|
From page 159... ...
In thinking about the possibilities and difficulties associated with optical imaging, it is necessary to realize that energy in the infrared range interacts with tissue in ways that are (lominate(1 by scattering, a phenomenon that is to a large extent absent when higher-energy portions of the electromagnetic spectrum are used. Although the scattering in optical imaging is at times confined to the forward direction, scattering effects accumulate over any thick specimen because the scattering coefficients in tissue are rather large and the clirectional beam of laser light is quickly converted into a disuse flux.
|
From page 160... ...
More work is required both to obtain mathematical formulations of complicated scattering environments and to assess the numerical stability of possible inversion algorithms for these highly nonlinear problems. Existing mathematical theory makes it likely that any reconstruction algorithms that emerge could be seriously ill-conditioned or sensitive to noise in the ciata.
|
From page 161... ...
In neonatal imaging, optical tomography has been used to assess tissue structure in ongoing trials to monitor the location and onset of hemorrhage (using both time-resolved and continuous-beam systems) ; in efforts to monitor strokes, it has been used to gain knowledge about functioning tissue, a task that does not require the high spatial image resolution needed for hemorrhage detection.
|
From page 162... ...
The living cornea, lens, and retina could be visualized in detail and their functions studied through careful optical scattering investigations. 11.5 Research Opportunities The central question in investigations of medical optical imaging is, How do human tissues an(1 other complex media propagate light, and what can be learned about those media through such study?
|
From page 163... ...
10. Fantini, S., Franceschini, M.A., FisDkin, I.B., Barbieri, B., et al., Quantitative determination of the absorption spectra of chromophores in strongly scattering media A light-emitting-diode based technique, Appl.
|
From page 164... ...
.B., and Gratton, E., Propagation of photon-density waves in strongly scattering media containing an absorbing semi-infinite plane bounded by a straight edge, ~7.
|
From page 165... ...
23. O'Leary, M.A., Boas, D.A., Chance, B., and Yodh, A.G., Reradiation and images of diffuse photon density waves using fluorescent inhomogeneities, ]
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.