Design of a novel non-contact temperature controlled surgical laser system

Abstract

Achieving repeatable and successful results without causing excessive collateral damage is of paramount importance for photothermal laser applications. Conventionally, dosimetry studies are conducted on laboratory animals to determine ideal laser parameters. Unfortunately, these predetermined parameters cannot ensure patient safety and treatment success in the clinic due to variance between optical and thermal characteristics among subjects. Controlling laser irradiation with tissue temperature feedback is the current gold standard for various photothermal treatments. In this dissertation, I present the development of a compact and easy to use non- contact radiometric temperature measurement and laser control system based on a commercial, inexpensive IRt/c sensor. This thesis study establishes the validity of my design that potentially makes temperature control more accessible in clinical environments. I have shown the ability of this system to maintain tissue temperature at a set value over extended durations (60 s) using ex vivo Wistar albino rat skin. Additionally, I evaluated the practical performance of this system by ex vivo photocoagulation of bovine liver using two independent variables: laser power and target temperature. Temperature-time responses of samples varied significantly, in agreement with our expectations, confirming a wide range of optical and thermal coefficients. Using target temperature as an independent variable, this system was successful in regulating the coagulation zone. Moreover, it was able to prevent undesired thermal damage in all but two samples (out of 144). I have also shown that this system can produce scientifically valuable information for photothermal characterization of tissues. NOTE Keywords : Temperature Regulation, Laser Control, Medical Laser Treatment, Photothermal Interactions.