The fragility of osteoporotic bones is largely due to alterations in the underlying structural geometry. Research has demonstrated that it is possible to measure the mechanical geometry of human bones in vivo using dual energy x-ray absorptiometry (DXA) scans. However DXA scanners are designed to measure bone mineral density (BMD) and not structural geometry. The 2-dimensional relatively poor quality images adequate for BMD are not well suited to measuring geometry of 3-dimensional bones. In this Phase I SBIR project we propose to use a full-sized benchtop system to test the properties of a multiple-projection DXA scanner designed to measure bone geometry in any body region with higher quality image data. The scanner will employ a multi-row array of counting detectors in a slot-scanning configuration to produce higher quality material decompositions and higher spatial resolution than any existing DXA system. The scanner is designed to accommodate projections through thick body regions or obese patients with little loss of SNR by adjusting the x-ray flux, scan time and or the spectral filter. In this project the system design will be completed so that a human capable prototype can be built and tested on humans in Phase 2. The C-arm gantry design is to be configured for scanning of the entire body with sizes from neonate to 99th percentile adults with the patient either recumbent or erect. It will also scan anybody sub-region in any axial projection. The system design employs a flexible detector interface and scanning configuration so that counting detectors from several vendors may be tested.
Bone densitometry scanners are designed to measure bone density as way to determine if patients are susceptible to osteoporotic fractures but current scanners are accurate only 50% of the time. The principles used in bone densitometry scanners can be employed to measure the bone structure for a more direct evaluation of bone strength, but scanners need better image quality and the ability to view bones from multiple directions. The purpose of this proposal is to test the principles of an x-ray scanner that uses spectral information to provide multiple high-quality views of patient's bones so that strength can be estimated using engineering methods. If successful a scanner capable of scanning patients either erect or recumbent will be built in Phase 2 and tested on human volunteers.