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Proceedings Paper

Quasi-cw tissue transillumination at 1064 nm
Author(s): Umberto Bernini; Antonio Ramaglia; Paolo Russo
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Paper Abstract

An extended series of transillumination experiments has been performed in vitro on animal samples (bovine muscle, up to 30- mm-thick; chicken wing and quail femur, 12-mm-thick) and in vivo on the human hand (thickness, about 20 mm), using a pulsed light source (7 ns, about 10-4 J/pulse, 10 Hz rep rate) from a collimated (1.2 m) Nd:YAG laser beam (1064 nm). A PIN photodiode connected to a digital oscilloscope was used to measure the maximum intensity of the beam pulse transmitted through the sample (i.e., no temporal discrimination of the output signal was attempted) while it was scanned across the source/detector assembly. One dimensional scans were performed on bovine muscle samples in which thin metallic test objects were embedded, in order to study the spatial resolution of the technique (for bovine muscle at 1064 nm, absorption and reduced scattering coefficients are reported to be about 1 cm-1 and 3 cm-1, respectively). The measured spatial resolution was as good as 3.6 mm in 30 mm of tissue thickness. In the two-dimensional scans of the chicken and quail sample, fat and bone tissues can be easily seen with good resolution, whereas imaging of the middle finger of a human hand shows cartilaginoid and bone tissue with 1 - 2 mm resolution. Hence, this simple collimated quasi-cw technique gives significantly better results for tissue imaging than pure cw transillumination. Use of (pulsed) light above 1000 nm and a high energy content per pulse are supposed to explain the positive experimental findings.

Paper Details

Date Published: 18 August 1997
PDF: 9 pages
Proc. SPIE 2979, Optical Tomography and Spectroscopy of Tissue: Theory, Instrumentation, Model, and Human Studies II, (18 August 1997); doi: 10.1117/12.280305
Show Author Affiliations
Umberto Bernini, Univ. of Napoli "Federico II" (Italy) and Instituto Nazionale per la Fisica della Materia (Italy)
Antonio Ramaglia, Instituto Nazionale per la Fisica della Materia (Italy)
Paolo Russo, Univ. of Napoli "Federico II" (Italy)

Published in SPIE Proceedings Vol. 2979:
Optical Tomography and Spectroscopy of Tissue: Theory, Instrumentation, Model, and Human Studies II
Britton Chance; Robert R. Alfano, Editor(s)

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