22 Bronchology – Past, Present and Future Diagnostic Procedures 3.  KARL STORZ D-LIGHT AF Autofluorescence System using Filtered Xenon Light – Direct Imaging Technique This unique system makes autofluorescence directly visible to the eye which is clearly different from the indirect techniques used in other autofluorescence systems. The system is minimally invasive and can be documented. Its basic principles are: •  White light (sunlight/incident light) is absorbed differently by different objects, it gives a picture, color, e.g. blood absorbs the blue and green parts of the light spectrum making it appear red. •  The incident light has a certain wavelength, and is backscattered. •  The wavelength of the backscattered light is the same as that of the incident light. •  Fluorescence is an effect that changes the wavelength of the incident light so that the re-emitted light is shifted into the red part of the spectrum. •  Autofluorescence is weak and is generated by tissue-inherent fluorochromes in the submucosa and can be made visible by eliminating the scattered light. •  The  blue  light  excitation  is  done  by  a  Xenon  lamp-based  light  source (KARL STORZ D-LIGHT AF). The wavelength of the incident light is blocked in the observation pathway. When the disturbing backscattered light is eliminated  by a filter the fluorescence is revealed. An observation filter mounted in the eyepiece of the endoscope separates the backscattered excitation light from the fluorescence light during observation in the fluorescence mode. •  Autofluorescence is an intrinsic feature of tissues and may be excited by exposing them to the blue part of the spectrum. Fluorescence induced by tumor markers is called xenofluorescence. When the relevant fluorochromes are excited by the blue part of the spectrum, fluorescence is induced. The penetration depth of blue light is only a fraction of a millimeter but still exceeds the penetration depth of UV light. Fluorescence originates in the submucosal layer. The modified activity of the tumor cells due to the malignant process leads to a lower number of fluorochromes (Tumor Selectivity of Autofluorescence), epithelial thickening and changes in the tumor matrix, which make the diseased tissue look darker than normal. The KARL STORZ D-LIGHT AF System uses a 300 W Xenon lamp in conjunc- tion with special fluorescence-capable endoscopes to focus the high intensity light into a fluid light guide optimized for blue light transmission in the autofluor- escence mode. Blue light output power for autofluorescence is 80 mW at the di- stal  tip  of  a  KARL  STORZ  fiberscope.  In  Combined  Bronchoscopy  flexible fiberscopes are alternately used with HOPKINS^®  Bronchoscopes (diameter 5.5 mm) of different viewing directions 0º, 30º, 90º. The KARL STORZ D-LIGHT AF System  offers  high  luminous  intensity;  the  spectral  transmission  curves  of excitation filter and observation filter are matched with a high degree of preci- sion to allow for reliable detection of suspect areas by means of  color contrast. Fiberscopes with diameters of 5.0 mm, 5.5 mm and 6.4 mm and a distal tip mobility of 180º and downward range of 100º/80º are used. Back –––––––Table of Contents–––––––Next Back –––––––Table of Contents–––––––Next