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. Author manuscript; available in PMC: 2011 Dec 1.
Published in final edited form as: Acad Radiol. 2010 Oct 14;17(12):1525–1534. doi: 10.1016/j.acra.2010.08.005

Fig. 2.

Fig. 2

The CT images of Tubes 1 and 4 and the graphs below the images were obtained using the public-domain program ImageJ. The graphs show the attenuation (in HU) along the line crossing the tube plotted as a function of distance. The maximum HU value of Tube 1 is much less than the airway tube attenuation, so the half-maximum point is near -700 HU. This will result in a calculated wall thickness that is too large.