Finite element analysis of the use of temperature feedback for control of laser coagulation in biological tissue
Glenn, Tami Neal
Tittel, Frank K.
Master of Science thesis
Study of thermal damage processes in laser irradiated tissue can provide further insight into the determination of optimal coagulation procedures. Arrhenius rate thermal damage processes are sensitive to tissue damage coefficients, tissue optical properties, and laser parameters. A specific isotherm appears to be associated with damage front position. Issues of coagulation control were considered by simulating a controlled surface temperature irradiation using thermal feedback to execute an appropriate temporal profile for laser power. A non-uniform pulse sequence achieves a 'constant' surface temperature. When operating the controlled temperature laser subject to convective boundary conditions, the surface temperature reference may need to be lowered to minimize subsurface heating effects. 'Constant' surface temperature irradiation avoids high temperature effects and substantial surface injury, achieves relatively slow, steady progression of damage, allowing potential real-time monitoring and control of coagulation front position, and is less sensitive to temperature dependent properties.
Biomedical engineering; Mechanical engineering