Feedback-controlled thermal therapy of tissues based on fiber Bragg grating thermometers

Accurate treatment monitoring and control are essential factors to ensure safe and effective outcomes of thermal ablation therapies. In this work, we report a temperature feedback-controlled laser ablation system based on fiber Bragg grating (FBG) array measurements. A highly spatially resolved array of FBGs spaced at a distance of 0.01 mm was adopted to achieve accurate measurement of high-gradient temperature profiles during laser ablation in biological tissue. The temperature feedback-control based on FBG array measurements and on the subsequent laser current regulation was implemented to maintain stable peak temperature during ablation. The laser current was controlled based on the selection of threshold values, set for the maximum temperature in the laser-irradiated area, i.e., 43 °C, 48 °C, 55 °C, and 60 °C. The feedback-controlled system was validated comparing measured temperature maps during ablation and ablation results on the tissue surface. Finally, results suggest that our feedback system allows controlling the spatial extension of the ablated zone and preserving the maximum tissue temperature within useful ranges for a desired and optimal thermal ablation outcome.