Pilot ex vivo study of laser induced breakdown spectroscopy for hard and soft tissue differentiation as a feedback system for tissue-specific laser surgery

The aim of this study is to provide an optical feedback mechanism for smart laser surgery tools focusing tissue classification using Laser Induced Breakdown Spectroscopy (LIBS) that monitors the plasma plume created during laser tissue interaction in surgery. A pulsed flash pump Nd:YAG laser in second harmonic which generates 532 nm beam with 5ns pulse width was used for the ablating tissue samples. The laser was run at 107 mJ pulse energy. Porcine fresh bone and muscle tissue were used as a hard and soft tissue samples, respectively. The generated plasma was collected using an 50um fiber optic connected to a UV-NIR light collector with F-number of 2 and the collected light was send to echelle spectrograph connected to an intensified CCD. The peaks related to the elements found in the samples and were in a good agreement with those described in literature. Finally, the recorded spectra were analyzed based on the intensity ratios of the well-known peaks of the calcium and sodium lines which was visible in both tissue types. The obtained preliminary results show a successful differentiation between hard and soft tissues samples to use as a real time feedback mechanism to improve the safety and sensitivity of clinical laser surgeries.