Dual energy inverse mapping technique to estimate calcium-to-phoshorus mass ratio in bone quality assessment
Μιχαήλ, Χρήστος Μ.
Μαρτίνη, Νίκη Δ.
Σωτηροπούλου, Παναγιώτα Ι.
Κούκου, Βάϊα Ν.
Φούντος, Γεώργιος Π.
Βαλαής, Ιωάννης Γ.
Κανδαράκης, Ιωάννης Σ.
Νικηφορίδης, Γεώργιος Χ.
Bone quality is a broad term encompassing factors affecting the structural and
material properties of bone. X-ray dual-energy method (XDEM) provides one way to
explore bone quality in terms of bone tissue material properties. In this study a XDEM
is presented for the determination of Ca/P mass ratio, parameter which appears to play
an important role in bone health. The low- and high-energy intensity measurements
were combined, using a nonlinear mapping function, to cancel out the soft tissue
structures and generate the dual energy (DE) Ca/P mass ratio value. The total
entrance-skin exposure from low- and high-energy measurements was constrained so
that it is similar to diagnostic-examination levels. The DE simulated data were
exported using variable Ca and PO4 thicknesses, while the tissue thickness was kept
constant. The thickness of each material was fitted separately using a nonlinear least
squares minimization algorithm. The functional forms of inverse functions that have
been investigated are the linear, quadratic, cubic, and conic functions. The inversemapping
functions were found to vary as analytic functions of second (conic) and
third (conic) order. A nonlinear eight term rational function was selected for dual
energy calibration which appeared to be capable of high fitting accuracy while
requiring relative few terms.
Special issue: 2nd Conference on Bio-Medical Instrumentation and related Engineering And Physical Sciences, Technological Educational Institute of Athens, Athens, 21 & 22 June 2013.
Sotiropoulou, P.I., Fountos, G.P., Martini, N.D., Koukou, V.N., Michail, C.M., et al. (2014). Dual energy inverse mapping technique to estimate calcium-to-phoshorus mass ratio in bone quality assessment. "e-Journal of Science & Technology". [Online] 9(4): 15-24. Available from: http://e-jst.teiath.gr/