Thomas Hangartner (Advisor)
Doctor of Philosophy (PhD)
The purpose of this work was to develop and evaluate single- and dual-energy radiographic absorptiometry (RA) for the measurement of mandibular bone mineral density (BMD), using standard dental equipment, that would allow for inexpensive and widespread osteoporosis screening. Accurately measured x-ray tube spectra are important for validating the simulations used in the design of the method. A constrained least-squares deconvolution technique for reducing the detector-induced blurring of the energy spectrum was developed. Application of this analytic correction to spectra acquired with a NaI-photomultiplier detector improved the measured data by 20-60%. Implementation of the screening method is accomplished by simultaneously acquiring high- and low-energy images on a single dental radiograph by appropriate filtering of the dental x-ray tube output. Computer simulations were performed to optimize the filters with respect to error in the bone measurement. A custom-designed film holder houses the beam filters and accommodates calibration wedges that allow the radiographs to be normalized for differences in exposure and developing conditions. Forty-six male and female subjects, ages 27 to 87 years, participated in a pilot study to assess the RA techniques. Left and right vertical periapical radiographs were taken of the premolar-molar region and, for comparison, the subjects’ BMD was evaluated at the spine, left and right femur as well as total body by dual-energy x-ray absorptiometry (DXA). Mandibular BMD by either high or low single-energy RA measurements was positively correlated with skeletal BMD, as assessed by DXA, at the arms, legs, trunk, ribs, pelvis, total body and femoral neck. ROC analysis of the single-energy techniques for identification of osteopenic and osteoporotic female subjects, as defined by DXA at the left femoral neck, yielded an area under the curve of 0.73. This is comparable to commercial devices currently used for screening and indicates that the RA method may be valuable for early diagnosis of low bone mass.
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Copyright 2003, all rights reserved. This open access ETD is published by Wright State University and OhioLINK.