Vol.96 No.6 contentsPRACTICA OTO-RHINO-LARYNGOLOGICA
Vol. 96 No.6 June 2003
Electronic Videoendoscopic
Observations of
the Pharynx and Larynx
Masahiro Kawaida
(Tokyo Metropolitan Ohtsuka Hospital)
Electronic videoendoscopy of the pharynx and larynx allows lesions to be visualized with precision. The images obtained using a charge-coupled device (CCD) chip are converted into electric signals and transmitted to the video system center. Clear, dynamic color images are reproduced on a color video monitor through a video system center. The basic components of an electronic videoendoscope system are a flexible endoscope, a video system center, a light source and a color video monitor.
There are two methods of capturing and reproducing dynamic color images in electronic videoendoscopy; the single-plate simultaneous color CCD chip method and the single-plate red, green, and blue (RGB) surface scanning method. In the former method, a color CCD chip built into the distal tip of the endoscope contains multiple color pixels and can simultaneously capture different color wavelength of light. In the latter method, the tip of the endoscope incorporates a monochrome CCD chip that can only provide black and white signals. The color CCD chip simplifies color acquisition but is considerably larger than the monochrome CCD chip, requiring a wider diameter than the distal tip of the endoscope. This is one of the reasons why the single-plate RGB surface scanning method is preferred in a rhinolaryngeal electronic videoendoscope system.
Digital image processing of lesions can be performed by electronic videoendoscopy. The enhanced color images are superior in quality.
Laryngostroboscopy is the most practical method of determining the vibratory pattern of the vocal folds during phonation. However, the laryngostroboscope cannot connect with the electronic videoendoscope system using a single-plate RGB scanning method because of the presence of a rotating wheel filter between the light source and glass fiber bundle of the light guide. To obtain stroboscopic images with an electronic videoendoscope system, a single-plate simultaneous color CCD chip method is necessary.
Recent advances in electronic technology enables production of the electronic videoendoscope system that can connect with a laryngostroboscope. The clear stroboscopic images of vocal fold vibration obtained by this system are described here.
Literature reviews of the history and development of electronic videoendoscopy were also performed from the perspective of diagnostic usefulness.
Key words : electronic videoendoscopy, pharynx, larynx, digital image processing, laryngostroboscopy