Background Laser Doppler flowmetry (LDF) is a non invasive technique for monitoring blood perfusion of tissue. The method is commercially available in a variety of technical implementations, and is the technique being used in various protocols for the same application. Apart from that, the technique in its present state only offers a relative measure of the perfusion, measured in an unknown tissue compartment.
The project was initiated by the major laser Doppler research groups and the leading European manufacturers of LDF equipment. The aims are:
1) to achieve standardization of the LDF technique and its protocols and;
2) to perform research into fundamental aspects of LDF.
1. Knowledge of the volume in tissue, as probed by the different instruments (monitoring and imaging);
2. Development of flow standards and perfusion flow calibration facilities;
3. Development of probes with standardised layout and performances;
4. Protocols and procedures, for use with clinical measurements, leading to a European standardisation of the technique for specific applications.
Work programme Development of flow standards for the determination of the linearity and probed volume of LDF instruments. Performance of Monte Carlo simulations for theoretical support of the measurements with the flow standard. Definition of a standard for LDF instruments, and realisation of various LDF instruments according to this standard. In vivo experiments (on animals and humans) to determine the performance of the instruments developed, and to elaborate standardized measurement protocols. Dissemination of these results. This must lead to acceptance of the standardised instruments and protocols. State of progress A tissue phantom has been developed that mimicks the layered optical structure of tissue on a realistic scale. Also, the effect of radiation on the tissue phantom tenability has been measured. Based on this phantom, a new calibrator prototype incorporating more and thinner moving layers was developed. Monte Carlo simulations of light scattering processes have been carried out to determine probed depth and path length as a function on tissue and probe parameters. A method has been conceived for correcting for path length variations between various tissue types, and a special probe has been developed for applying this method. A start was made with developing a tester for the laser Doppler imager that contains typical features of imaging experiments, like roughness and curvature of the tissue surface. A start is made with the definition of standardised laser Doppler instruments. The essential parameters have been identified, and a start has been made with determining the values that will fall within a standard.
Funding SchemeCSC - Cost-sharing contracts
02 109 Warszawa
581 85 Linköping
205 02 Malmö
EX13 5DT Axminster
OX4 4GA Oxford
175 26 Järfälla
9712 KZ Groningen