NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Cross-sectional structural parameters from densitometryBone densitometry has previously been used to obtain cross-sectional properties of bone from a single X-ray projection across the bone width. Using three unique projections, we have extended the method to obtain the principal area moments of inertia and orientations of the principal axes at each scan cross-section along the length of the scan. Various aluminum phantoms were used to examine scanner characteristics to develop the highest accuracy possible for in vitro non-invasive analysis of cross-sectional properties. Factors considered included X-ray photon energy, initial scan orientation, the angle spanned by the three scans (included angle), and I(min)/I(max) ratios. Principal moments of inertia were accurate to within +/-3.1% and principal angles were within +/-1 degrees of the expected value for phantoms scanned with included angles of 60 degrees and 90 degrees at the higher X-ray photon energy (140 kVp). Low standard deviations in the error (0.68-1.84%) also indicate high precision of calculated measurements with these included angles. Accuracy and precision decreased slightly when the included angle was reduced to 30 degrees. The method was then successfully applied to a pair of excised cadaveric tibiae. The accuracy and insensitivity of the algorithms to cross-sectional shape and changing isotropy (I(min)/I(max)) values when various included angles are used make this technique viable for future in vivo studies.
Document ID
20040088389
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Cleek, Tammy M.
(NASA Ames Research Center Moffett Field CA United States)
Whalen, Robert T.
Date Acquired
August 21, 2013
Publication Date
April 1, 2002
Publication Information
Publication: Journal of biomechanics
Volume: 35
Issue: 4
ISSN: 0021-9290
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
NASA Center ARC
NASA Discipline Musculoskeletal

Available Downloads

There are no available downloads for this record.
No Preview Available