An in-vitro analysis of two laser Doppler flowmetry systems for evaluation of bone perfusion

Laser Doppler Flowmetry (LDF) has been shown to be a useful tool in the experimental and clinical measurement of bone blood flow. Two LDF receiving fiber channel systems, one with a 2mW He-Ne tube laser source and the other with an infrared diode laser source, were compared with specific reference to their light attenuation through three types of bone as well as their threshold thickness for the same specimens. The threshold thickness was higher for the infrared diode system for all three bone types whereas the attenuation was identical. The demonstrated differences were most likely due to the criteria established for flow detection; the infrared diode system has a greater degree of amplification of the output signal, yielding a higher value at each thickness of bone. The two systems will produce similar output data when used for experimental analysis of bone blood flow.