title: The effects of laser repetition rate on femtosecond laser ablation of dry bone: a thermal and LIBS study.
abstract: The aim of this study is to understand the effect of varying laser repetition rate on thermal energy accumulation and dissipation as well as femtosecond Laser Induced Breakdown Spectroscopy (fsLIBS) signals, which may help create the framework for clinical translation of femtosecond lasers for surgical procedures. We study the effect of repetition rates on ablation widths, sample temperature, and LIBS signal of bone. SEM images were acquired to quantify the morphology of the ablated volume and fsLIBS was performed to characterize changes in signal intensity and background. We also report for the first time experimentally measured temperature distributions of bone irradiated with femtosecond lasers at repetition rates below and above carbonization conditions. While high repetition rates would allow for faster cutting, heat accumulation exceeds heat dissipation and results in carbonization of the sample. At repetition rates where carbonization occurs, the sample temperature increases to a level that is well above the threshold for irreversible cellular damage. These results highlight the importance of the need for careful selection of the repetition rate for a femtosecond laser surgery procedure to minimize the extent of thermal damage to surrounding tissues and prevent misclassification of tissue by fsLIBS analysis.
authors.affiliation: Center for Biophotonics, University of California, Davis, Sacramento, CA, 95817, USA.|Department of Biomedical Engineering, University of California, Davis, Davis, CA, 95616, USA.
authors.forename: Ruby K
authors.initials: RK
authors.lastname: Gill
authors.affiliation: Center for Biophotonics, University of California, Davis, Sacramento, CA, 95817, USA.
authors.forename: Zachary J
authors.initials: ZJ
authors.lastname: Smith
authors.affiliation: Center for Biophotonics, University of California, Davis, Sacramento, CA, 95817, USA.
authors.forename: Changwon
authors.initials: C
authors.lastname: Lee
authors.affiliation: Center for Biophotonics, University of California, Davis, Sacramento, CA, 95817, USA. swachsmann@ucdavis.edu.|Department of Pathology, University of California, Davis, Sacramento, CA, 95817, USA. swachsmann@ucdavis.edu.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Wachsmann-Hogiu
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000601:surgery*; D002417:Cattle; D053685:Laser Therapy; D013696:Temperature; D013997:Time Factors
keywords: Ablation feedback; laser repetition rate; laser surgery; thermal dissipation; ultra-short lasers