A spectroscopic approach to monitor the cut processing in pulsed laser osteotomy

Abstract

During laser osteotomy surgery, plasma arises at the place of ablation. It was the aim of this study to explore whether a spectroscopic analysis of this plasma would allow identification of the type of tissue that was affected by the laser. In an experimental setup (Rofin SCx10, CO(2) Slab Laser, wavelength 10.6 μm, pulse duration 80 μs, pulse repetition rate 200 Hz, max. output in cw-mode 100 W), the plasma spectra evoked by a pulsed laser, cutting 1-day postmortem pig and cow bones, were recorded. Spectra were compared to the reference spectrum of bone via correlation analysis. Our measurements show a clear differentiation between the plasma spectra when cutting either a bone or a soft tissue. The spectral changes could be detected from one to the next spectrum within 200 ms. Continuous surveillance of plasma spectra allows us to differentiate whether bone or soft tissue is hit by the last laser pulse. With this information, it may be possible to stop the laser when cutting undesired soft tissue and to design an automatic control of the ablation process.

Combined Nd:YAG and Er:YAG lasers for real-time closed-loop tissue-specific laser osteotomy

“…In order to preserve the adjacent soft tissue, several approaches to such differentiation have been developed using the optical properties of the ablated tissues. These methods include optical coherence tomography (OCT) [12,13], Raman spectroscopy [14][15][16][17], autofluorescence spectroscopy [18,19], diffuse reflectance spectroscopy (DRS) [20][21][22][23], ablative optoacoustic techniques [24][25][26][27][28][29], random lasing [30], laser-induced breakdown spectroscopy (LIBS) [31][32][33][34][35][36][37][38][39][40][41][42], and combustion/pyrolysis light analysis [43,44]. However, many of these methods have not been tested in combination with an ablating laser; studies have focused on tissue differentiation only.…”

Laser-induced breakdown spectroscopy as a potential tool for autocarbonization detection in laserosteotomy

“…The potential optical detection methods to investigate the properties of the tissues include optoacoustic-based measurements 19,20 and also spectroscopy-based measurements, including diffuse reflectance, 21,22 laser-induced breakdown, [23][24][25] Raman, 26,27 and fluorescence spectroscopy. 28,29 Among the above-mentioned optical methods, laser-induced breakdown spectroscopy (LIBS) showed its potential to detect the type of tissue with high accuracy.…”

Differentiation of femur bone from surrounding soft tissue using laser-induced breakdown spectroscopy as a feedback system for smart laserosteotomy

“…In comparison to well established mechanical instruments for cutting bone, laserosteotomes provide several important benefits like functional cuts, minimal invasiveness, non-contact interaction, and accelerated healing [1][2][3][4][5][6][7][8][9][10]. At the same time, they still suffer from a lack of feedback on the type and properties of the tissue being cut; as a result, critical structures of the body under the laser line are prone to iatrogenic damage [11][12][13][14][15]. The lack of information on the type of tissue being ablated by the laserosteotome limits its application as a minimally invasive osteotomy tool.…”