Quantification of the magnification and distortion effects of a pediatric flexible video-bronchoscope

Masters, I. B., Eastburn, M. M., Francis, P. W., Wootton, R., Zimmerman, P. V., Ware, R. S. and Chang, A. B. (2005) Quantification of the magnification and distortion effects of a pediatric flexible video-bronchoscope. Respiratory Research, 6 9: 16-1-16-9.


Author Masters, I. B.
Eastburn, M. M.
Francis, P. W.
Wootton, R.
Zimmerman, P. V.
Ware, R. S.
Chang, A. B.
Title Quantification of the magnification and distortion effects of a pediatric flexible video-bronchoscope
Journal name Respiratory Research   Check publisher's open access policy
ISSN 1465-9921
Publication date 2005-02-10
Sub-type Article (original research)
DOI 10.1186/1465-9921-6-16
Volume 6
Issue 9
Start page 16-1
End page 16-9
Total pages 9
Place of publication London, U.K.
Publisher BioMed Central
Collection year 2005
Language eng
Subject C1
321027 Respiratory Diseases
329999 Medical and Health Sciences not elsewhere classified
730110 Respiratory system and diseases (incl. asthma)
730305 Diagnostic methods
1117 Public Health and Health Services
Abstract Background: Flexible video bronchoscopes, in particular the Olympus BF Type 3C160, are commonly used in pediatric respiratory medicine. There is no data on the magnification and distortion effects of these bronchoscopes yet important clinical decisions are made from the images. The aim of this study was to systematically describe the magnification and distortion of flexible bronchoscope images taken at various distances from the object. Methods: Using images of known objects and processing these by digital video and computer programs both magnification and distortion scales were derived. Results: Magnification changes as a linear function between 100 mm ( x 1) and 10 mm ( x 9.55) and then as an exponential function between 10 mm and 3 mm ( x 40) from the object. Magnification depends on the axis of orientation of the object to the optic axis or geometrical axis of the bronchoscope. Magnification also varies across the field of view with the central magnification being 39% greater than at the periphery of the field of view at 15 mm from the object. However, in the paediatric situation the diameter of the orifices is usually less than 10 mm and thus this limits the exposure to these peripheral limits of magnification reduction. Intraclass correlations for measurements and repeatability studies between instruments are very high, r = 0.96. Distortion occurs as both barrel and geometric types but both types are heterogeneous across the field of view. Distortion of geometric type ranges up to 30% at 3 mm from the object but may be as low as 5% depending on the position of the object in relation to the optic axis. Conclusion: We conclude that the optimal working distance range is between 40 and 10 mm from the object. However the clinician should be cognisant of both variations in magnification and distortion in clinical judgements.
Keyword Respiratory System
Flexible bronchoscopy
Pediatric
Magnification
Distortion
Q-Index Code C1
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