title: Laser projection imaging for measurement of pediatric voice.
abstract: OBJECTIVE
  The aim of the study was to present the development of a miniature laser projection endoscope and to quantify vocal fold length and vibratory amplitude of the pediatric glottis using high-speed digital imaging coupled with the laser endoscope.
  
  
  METHODS
  For this prospective study, absolute measurement of entire vocal fold length, membranous length of the vocal fold, and vibratory amplitude during phonation were obtained in one child (9 years old), one adult male (36 years old), and one adult female (20 years old) with the use of high-speed digital imaging, coupled with a custom-developed laser projection endoscope.
  
  
  METHODS
  The laser projection system consists of a module slip-fit sleeve with two 3-mW 650-nm laser diodes in horizontal orientation separated by a distance of 5 mm. Calibration involved projecting the laser onto grid patterns at depths ranging from 6 to 10 cm and tilt angles of 15 to -5 degrees to obtain pixel-to-millimeter conversion templates. Measurements of vocal fold length and vibratory amplitude were extracted based on methods of image processing.
  
  
  RESULTS
  The system demonstrated a method for estimating vocal fold length and vibratory amplitude with a single laser point with high measurement precision. First measurements of vocal fold length (6.8 mm) and vibratory amplitude (0.25 mm) during phonation in a pediatric participant are reported.
  
  
  CONCLUSIONS
  The proposed laser projection system can be used to obtain absolute length and vibratory measurements of the pediatric glottis. The projection system can be used with stroboscopy or high-speed digital imaging systems with a 70-degree rigid endoscope.
authors: Department of Rehabilitation Sciences, Division of Communication Sciences and Disorders, University of Kentucky, Lexington, Kentucky 40536-0200, USA. rita.patel@uky.edu
authors: Rita R
authors: RR
authors: Patel
authors: Kevin D
authors: KD
authors: Donohue
authors: Weston C
authors: WC
authors: Johnson
authors: Sanford M
authors: SM
authors: Archer
mesh_terms: D000328:Adult; D000367:Age Factors; D002648:Child; D004867:Equipment Design; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D020704:Laryngoscopes; D007834:Lasers; D008297:Male; D010699:Phonation / Q000502:physiology*; D011446:Prospective Studies; D012016:Reference Values; D014732:Vibration; D014827:Vocal Cords / Q000033:anatomy & histology* / Q000502:physiology*; D055815:Young Adult