Date on Master's Thesis/Doctoral Dissertation


Document Type

Master's Thesis

Degree Name

M. Eng.


Mechanical Engineering

Committee Chair

Hnat, William Patrick


Bone densitometry


The field of bone densitometry has grown rapidly, particularly in the past 15 years. Many techniques are now available from which the physician may choose. The focus of this research is on Dual-Energy X-Ray Absorptiometry (DXA) and Quantitative Computed Tomography (QCT). The basic principle involving DXA is the ability to quantify the degree of attenuation of an energy beam after passage through bone and soft tissue. The X-ray tubes used with DXA narrow the energy beam to produce two distinct photoelectric peaks necessary to separate bone from soft tissue. Although QCT is a photon absorptiometric technique like DXA, it is unique in that it provides a three-dimensional image, which makes possible a direct measurement of density, and a spatial separation of trabecular from cortical bone. In this paper, a rabbit and pig femur were scanned using a DXA and QCT scanner. The purpose was to achieve matching results in g/cm2 from each scanner. Similar sections of interest were taken during each scan for calculation. The QCT grayscale values were then put into a series of formulas to replicate DXA results.