Detection of Intraorbital Foreign Material Using MDCT

Hoffstetter, P. and Friedrich, C. and Framme, C. and Hoffstetter, M. and Zorger, N. and Stierstorfer, K. and Ross, C. and Uller, W. and Mueller-Wille, R. and Rennert, J. and Jung, E. M. and Schreyer, A. G. (2011) Detection of Intraorbital Foreign Material Using MDCT. ROFO-FORTSCHRITTE AUF DEM GEBIET DER RONTGENSTRAHLEN UND DER BILDGEBENDEN VERFAHREN, 183 (6). pp. 543-548. ISSN 1438-9029,

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Abstract

Aim: To judge the possibilities of detection of orbital foreign bodies in multidetector CT (MDCT) with a focus on glass slivers. Materials and Methods: Experimental systematic measuring of Hounsfield Units (HU) of 20 different materials, containing 16 different types of glass with 4 different types of ophthalmic lenses among them. The measurements were performed using a standardized protocol with an orbita phantom being scanned with 16-slice MDCT. Using the resulting density values, the smallest detectable volume was calculated. Using this data we produced slivers of 5 different glass types in the sub-millimeter range and calculated their volume. Those micro-slivers underwent another CT scan using the same protocol as mentioned above to experimentally discern and confirm the detection limit for micro-slivers made of different materials. Results: Glass has comparatively high density values of at least 2000 HU. The density of glasses with strong refraction is significantly higher and reaches up to 12 400 HU. We calculated a minimum detectable volume of 0.07 mm(3) for glass with a density of 2000 HU. Only glass slivers with a density higher than 8300 HU were experimentally detectable in the sub-millimeter range up to a volume as small as 0.01 mm(3). Less dense glass slivers could not be seen, even though their volume was above the theoretically calculated threshold for detection. Conclusion: Due to its high density of at least 2000 HU, glass is usually easily recognizable as an orbital foreign body. The detection threshold depends on the object's density and size and can be as low as 0.01 mm(3) in the case of glass with strong refraction and thus high density. The detection of glass as an orbital foreign body seems to be secure for slivers with a volume of at least 0.2 mm(3) for all types of glass.

Item Type: Article
Uncontrolled Keywords: OPEN GLOBE INJURIES; COMPUTED-TOMOGRAPHY; BODIES; CT; EPIDEMIOLOGY; GLASS; eye; CT; experimental study; trauma; CT spiral
Subjects: 600 Technology > 610 Medical sciences Medicine
Divisions: Medicine > Lehrstuhl für Röntgendiagnostik
Depositing User: Dr. Gernot Deinzer
Date Deposited: 09 Jun 2020 09:56
Last Modified: 09 Jun 2020 09:56
URI: https://pred.uni-regensburg.de/id/eprint/20696

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