Olympus endview gastroscope1/12/2023 Some understanding of specific bronchoscopic magnification and distortion is an important issue to the clinician as these instruments are being used more regularly to define the nature and severity of airway lesions such as tracheal stenosis and malacia disorders from which important medical and surgical decisions ultimately follow. The flexible bronchoscope has been used in pediatrics for more than 20 years yet there are only a limited number of publications on the systematic examination of the physical properties of magnification and distortion found in endoscopes of any size, let alone bronchoscopes specific for the pediatric sized airways. 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. Distortion occurs as both barrel and geometric types but both types are heterogeneous across the field of view. Intraclass correlations for measurements and repeatability studies between instruments are very high, r = 0.96. 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. 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. Magnification depends on the axis of orientation of the object to the optic axis or geometrical axis of the bronchoscope. Magnification changes as a linear function between 100 mm (×1) and 10 mm (×9.55) and then as an exponential function between 10 mm and 3 mm (×40) from the object. However the clinician should be cognisant of both variations in magnification and distortion in clinical judgements. 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.ConclusionWe conclude that the optimal working distance range is between 40 and 10 mm from the object. The aim of this study was to systematically describe the magnification and distortion of flexible bronchoscope images taken at various distances from the object.MethodsUsing images of known objects and processing these by digital video and computer programs both magnification and distortion scales were derived.ResultsMagnification changes as a linear function between 100 mm (x1) and 10 mm (x9.55) and then as an exponential function between 10 mm and 3 mm (x40) from the object. There is no data on the magnification and distortion effects of these bronchoscopes yet important clinical decisions are made from the images. BackgroundFlexible video bronchoscopes, in particular the Olympus BF Type 3C160, are commonly used in pediatric respiratory medicine.
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