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Accurate Measurement of Bone Density with QCTThe objective of this study was to determine the accuracy of bone density measurement with a new OCT technology. A phantom was fabricated using two materials, a water-equivalent compound and hydroxyapatite (HA), combined in precise proportions (QRM GrnbH, Germany). The phantom was designed to have the approximate physical size and range in bone density as a human calcaneus, with regions of 0, 50, 100, 200, 400, and 800 mg/cc HA. The phantom was scanned at 80, 120 and 140 KVp with a GE CT/i HiSpeed Advantage scanner. A ring of highly attenuating material (polyvinyl chloride or teflon) was slipped over the phantom to alter the image by introducing non-axi-symmetric beam hardening. Images were corrected with a new OCT technology using an estimate of the effective X-ray beam spectrum to eliminate beam hardening artifacts. The algorithm computes the volume fraction of HA and water-equivalent matrix in each voxel. We found excellent agreement between expected and computed HA volume fractions. Results were insensitive to beam hardening ring material, HA concentration, and scan voltage settings. Data from all 3 voltages with a best fit linear regression are displays.
Document ID
20020054498
Acquisition Source
Ames Research Center
Document Type
Conference Paper
Authors
Cleek, Tammy M.
(NASA Ames Research Center Moffett Field, CA United States)
Beaupre, Gary S.
(Palo Alto VA Health Care System Palo Alto, CA United States)
Matsubara, Miki
(NASA Ames Research Center Moffett Field, CA United States)
Whalen, Robert T.
(NASA Ames Research Center Moffett Field, CA United States)
Dalton, Bonnie P.
Date Acquired
August 20, 2013
Publication Date
January 1, 2002
Subject Category
Aerospace Medicine
Meeting Information
Meeting: 15th International Bone Densitometry Workshop
Location: Monterey, CA
Country: United States
Start Date: July 21, 2002
End Date: July 26, 2002
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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