Near-infrared laser speckle imaging of human breast tissue
Current methods of breast cancer diagnostics (self-exam, clinical exam, x-ray mammography) fail to diagnose a significant number of cases while still in readily operable stages. This is especially true in younger women, where fibrotic tissue reduces the efficacy of x-ray mammography. Near infrared (NIR) laser photons pass diffusively through human tissue, creating a speckle pattern in a detector after transmission. The high and low intensity variations of the speckle have the appearance of random noise, but are not. The speckle pattern will have an intensity distribution that is informative about the scattering and absorption properties of the tissue that is imaged. Adaptations to the Los Alamos National Laboratory MCNP code are described that allow simulation of NIR laser transport through human tissue. A HeNe laser was used to create laser intensity patterns via transmission through homogeneous and non-homogeneous tissue phantoms. The Kolmogorov-Smirnov test was used to compare the cumulative distribution functions of the laser intensity patterns, and identify the presence of a non-homogeneity. Laser speckle techniques offer the ability to image tumors with few (<3) millimeter resolution without ionizing radiation dose.
Choi, Purdue University.
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