Laser Characteristics on Hard Tissue Laser Machining

• Published in: Sensors & transducers Vol. 226; no. 10; pp. 17 - 36
• Main Authors: Shayeganrad, Gholamreza, Mashhadi, Leila
• Format: Journal Article
• Language: English
• Published: Toronto IFSA Publishing, S.L 01.10.2018
• Subjects: Ablative materials; Absorption; Biocompatibility; Biomedical materials; Bone surgery; Bones; Dependence; Efficiency; Energy; Energy dissipation; Energy transfer; Geometry; Heat; Infrared lasers; Laser ablation; Laser cooling; Laser machining; Laser surgery; Moisture content; Orthopedics; Parameters; Remote sensing; Scattering
• ISSN: 2306-8515; 1726-5479

Laser ablation of hard-tissue is coming today the most common medical application of the laser, mainly because of ability to cut faster, less invasive, and free incision geometry with a higher quality than the competing processes. Great efforts have been taken in the past to develop laser systems suitable for efficient laser ablation of hard-tissue. One of the drawbacks of the water-cooled laser-assisted bone cutting process is the limitation in incision depth. There are two main energy loss mechanisms which limit the achievable depth in addition to the absorption and scattering of laser energy by water. The first is the growing heat diffusion from the increasing surface area of the incision. The second is the increasing absorption and scattering of laser light by the ablation debris which is confined in deeper cuts. The desired specifications on the laser hard tissue ablation vary a lot in terms of laser parameters. In this paper, the influence of main laser parameters on water-cooled hard tissue laser ablation is reviewed. In particular, the role of the laser intensity, wavelength, duration of the laser pulse on depth of incision and mechanisms of photon energy transfer to biomedical materials are presented. In addition, the dependence of the ablation efficiency AE on the water content of the hard-tissue is presented. Finally, we presented a novel method that can bypass the limitation of the incision depth that can be introduced to laser osteotomy by long-pulsed mid-infrared lasers. In this technique an array of rotational micro-lens combined with a normal lens focuses the laser light on the bone tissue sample to increase the maximal incision depth.