Multimodal feedback systems for smart laser osteotomy: Depth control and tissue differentiation

Abstract

ObjectivesThe study aimed to improve the safety and accuracy of laser osteotomy (bone surgery) by integrating optical feedback systems with an Er:YAG laser. Optical feedback consists of a real‐time visual feedback system that monitors and controls the depth of laser‐induced cuts and a tissue sensor differentiating tissue types based on their chemical composition. The developed multimodal feedback systems demonstrated the potential to enhance the safety and accuracy of laser surgery.Materials and MethodsThe proposed method utilizes a laser‐induced breakdown spectroscopy (LIBS) system and long‐range Bessel‐like beam optical coherence tomography (OCT) for tissue‐specific laser surgery. The LIBS system detects tissue types by analyzing the plasma generated on the tissue by a nanosecond Nd:YAG laser, while OCT provides real‐time monitoring and control of the laser‐induced cut depth. The OCT system operates at a wavelength of 1288 ± 30 nm and has an A‐scan rate of 104.17 kHz, enabling accurate depth control. Optical shutters are used to facilitate the integration of these multimodal feedback systems.ResultsThe proposed system was tested on five specimens of pig femur bone to evaluate its functionality. Tissue differentiation and visual depth feedback were used to achieve high precision both on the surface and in‐depth. The results showed successful real‐time tissue differentiation and visualization without any visible thermal damage or carbonization. The accuracy of the tissue differentiation was evaluated, with a mean absolute error of 330.4 μm and a standard deviation of ±248.9 μm, indicating that bone ablation was typically stopped before reaching the bone marrow. The depth control of the laser cut had a mean accuracy of 65.9 μm with a standard deviation of ±45 μm, demonstrating the system's ability to achieve the pre‐planned cutting depth.ConclusionThe integrated approach of combining an ablative laser, visual feedback (OCT), and tissue sensor (LIBS) has significant potential for enhancing minimally invasive surgery and warrants further investigation and development.

Assessment of the Electrolyte Heterogeneity of Tissues in Mandibular Bone-Infiltrating Head and Neck Cancer Using Laser-Induced Breakdown Spectroscopy

“…Preliminary work available in the literature on LIBS-based ex vivo tissue discrimination between oral hard and soft tissues [ 9 ], between fat and nerve [ 10 ], and between cartilage and bone [ 12 ] demonstrated the potential suitability of LIBS as a spectroscopic-optical sensor for controlled feedback in the context of tissue-specific laser ablation in the head and neck region. The integration of LIBS into a laser system with a tissue-ablating laser also appears technically feasible [ 13 , 14 , 15 ]. Since the knowledge gained from porcine spectra is not necessarily suitable for the in vivo classification of human tissues [ 15 , 24 ], knowledge of LIBS-based tissue detection on human sample material is required.…”

“…In this way, LIBS could potentially support radiation oncologists in the development of complex treatment plans and improve the effectiveness of radiotherapy. Regarding the development of clinical multimodal laser surgery systems, optical coherence tomography (OCT) provides promising results for additional real-time feedback and depth control of laser shots [ 13 , 44 ].…”

“…Promising results on the LIBS-based differentiation of various hard and soft tissues of the porcine head region have led to theoretical considerations of clinical laser surgery systems with tissue-specific laser ablation [ 9 , 10 , 11 , 12 ]. More recently, the potential synergistic effects of laser ablation and laser-assisted tissue detection have been substantiated by combining LIBS systems with tissue-ablating Er:YAG lasers [ 13 , 14 , 15 ]. However, research efforts on laser surgery systems with controlled tissue feedback in the head and neck region are currently limited to animal specimens and the use of nontumorous tissues [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ].…”

“…More recently, the potential synergistic effects of laser ablation and laser-assisted tissue detection have been substantiated by combining LIBS systems with tissue-ablating Er:YAG lasers [ 13 , 14 , 15 ]. However, research efforts on laser surgery systems with controlled tissue feedback in the head and neck region are currently limited to animal specimens and the use of nontumorous tissues [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ].…”