title: Determination of detection depth of optical probe in pedicle screw measurement device.
abstract: BACKGROUND
  There is a high probability of accidental perforation of the vertebral pedicle wall in pedicle screw insertion surgery. A pedicle screw (PS) measurement device with an optical probe has been reported to send out a warning signal before the PS tip breaking the vertebral pedicle wall.
  
  
  METHODS
  In this study, we explored the detection depth of optical probe in this measurement device, which was closely related to the effective alarm distance. In the boundary, the vertebrae tissues could be treated as 2-layer models including spongy bones and compact bones. The Monte Carlo simulation and phantom models were performed to analyse and define the detection depth. Then the porcine vertebrae models were performed to obtain optical spectrum and reduced scattering coefficient, based on which the detection depths were deduced. Moreover, a comparison was made to explore the most significant pattern factor from the experiment results.
  
  
  RESULTS
  According to the pattern factor, an alarm threshold was successfully deduced to define the alarm distance during pedicle screw monitoring.
  
  
  CONCLUSIONS
  Thus, the proposed alarm standard based on detection depth provides a potential for guiding pedicle screw in surgery.
authors.forename: Weitao
authors.initials: W
authors.lastname: Li
authors.forename: Yangyang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Biomedical Engineering, Nanjing University of Aeronautics and Astronautics, Yudao Street, Nanjing, China. zhiyu@nuaa.edu.cn.
authors.forename: Zhiyu
authors.initials: Z
authors.lastname: Qian
mesh_terms: D000465:Algorithms; D000818:Animals; D001842:Bone and Bones / Q000033:anatomy & histology; D003198:Computer Simulation; D004867:Equipment Design; D008159:Lumbar Vertebrae / Q000033:anatomy & histology; D009010:Monte Carlo Method; D055095:Optics and Photonics; D065289:Pedicle Screws; D019047:Phantoms, Imaging; D011336:Probability; D012542:Scattering, Radiation; D019265:Spectroscopy, Near-Infrared; D013552:Swine; D014057:Tomography, X-Ray Computed