5 August 1993 Ultrashort laser pulse propagation and imaging in biological tissue and model random media: steps towards optical mammography
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Proceedings Volume 10311, Medical Optical Tomography: Functional Imaging and Monitoring; 103110P (1993) https://doi.org/10.1117/12.2283770
Event: Medical Optical Tomography: Functional Imaging and Monitoring, 1993, Bellingham, WA, United States
Abstract
Ultrashort laser pulses passing through a random turbid medium are temporally spread into ballistic, snake, and diffuse components. The intensity and the speed of the ballistic pulse are found to depend on the scattering characteristics of the medium. The diffuse component can be approximated by the diffusion theory when the laser pulse propagates through a distance of more than 10 transport mean free path. The early arriving portion of the diffuse pulse, known as the snake component, consists of photons that propagate along zig-zag paths slightly off the straight path. The attenuation of the snake photon depends on the transport mean free path of the random medium and it decreases exponentially as its thickness increases. However, the snake photon attenuates much more slowly than the ballistic photon. Snake photons have to be used for time-resolved imaging through a thick biological tissue. Ultrafast time-resolved detection of ballistic and snake photons are illustrated for locating opaque and translucent objects hidden in highly scattering media. A thin slab of chicken fat tissue (2.5 mm thick) embedded inside a thick chicken breast tissue (40 mm) has been located by detecting snake photons at X.625 nm. Near infrared light is scattered less in tissue and can be used to image through a significantly thicker tissue. The current ultrashort pulse lasers and ultrafast time-resolved detection techniques can be potentially used to image tumors in a breast.
© (1993) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
K. M. Yoo, K. M. Yoo, } "Ultrashort laser pulse propagation and imaging in biological tissue and model random media: steps towards optical mammography", Proc. SPIE 10311, Medical Optical Tomography: Functional Imaging and Monitoring, 103110P (5 August 1993); doi: 10.1117/12.2283770; https://doi.org/10.1117/12.2283770
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