The propagation of ps-laser-pulses through different bone structures

Abstract

First results of angle and time resolved light scattering measurements performed on normal and osteoporotic human bone tissue are presented. The principle of measurement is based on time-correlated single photon counting (TCSPC) using a 10 ps laser diode (830 nm) and a micro channel plate- (MCP-) photomultiplier tube. In vitro results on human lumbar vertebrae (L1) obtained with this equipment show a correlation between the full width at half maximum (FWHM) of the scattered light pulses and the bone mineral densities (BMD) determined by Dual X-ray absorptiometry (DXA). The angle dependent scattering curves in vitro give distinct indications on the bone status in transmission mode. The in vivo measurements were taken of the 3rd phalanx of human probands, i. e. the 3rd bone of a person's middle finger, and the results are compared with those obtained by DXA (Lunar Expert) measurements. The FWHM-values of the transit time distributions of laser pulses scattered by the phalanx are linearly correlated with high significance (P< 0.0005) to the BMD values extracted from DXA measurements.