title: Calibration of laryngeal endoscopic high-speed image sequences by an automated detection of parallel laser line projections.
abstract: High-speed laryngeal endoscopic systems record vocal fold vibrations during phonation in real-time. For a quantitative analysis of vocal fold dynamics a metrical scale is required to get absolute laryngeal dimensions of the recorded image sequence. For the clinical use there is no automated and stable calibration procedure up to now. A calibration method is presented that consists of a laser projection device and the corresponding image processing for the automated detection of the laser calibration marks. The laser projection device is clipped to the endoscope and projects two parallel laser lines with a known distance to each other as calibration information onto the vocal folds. Image processing methods automatically identify the pixels belonging to the projected laser lines in the image data. The line detection bases on a Radon transform approach and is a two-stage process, which successively uses temporal and spatial characteristics of the projected laser lines in the high-speed image sequence. The robustness and the applicability are demonstrated with clinical endoscopic image sequences. The combination of the laser projection device and the image processing enables the calibration of laryngeal endoscopic images within the vocal fold plane and thus provides quantitative metrical data of vocal fold dynamics.
authors: Siemens Audiologische Technik GmbH, RD Signal Processing, Gebbertstrasse 125, 91058 Erlangen, Germany. Tobias.Wurzbacher@siemens.com
authors: Tobias
authors: T
authors: Wurzbacher
authors: Ingmar
authors: I
authors: Voigt
authors: Raphael
authors: R
authors: Schwarz
authors: Michael
authors: M
authors: Döllinger
authors: Ulrich
authors: U
authors: Hoppe
authors: Jochen
authors: J
authors: Penne
authors: Ulrich
authors: U
authors: Eysholdt
authors: Jörg
authors: J
authors: Lohscheller
mesh_terms: D000465:Algorithms; D002138:Calibration; D006801:Humans; D007828:Laryngoscopy / Q000379:methods*; D007834:Lasers; D010699:Phonation / Q000502:physiology*; D014827:Vocal Cords / Q000502:physiology*