Dual energy x-ray absorptiometry: The effects of beam hardening on bone density measurements

摘要: X‐ray tubes have superseded radionuclide sources for dual photon absorptiometry of the spine and hip. However, use a polyenergetic spectrum is potential source error x‐ray absorptiometers since beam hardening may result in nonlinear measurement scale bone mineral density (BMD). A quantitative study effects on measurements made with commercial energy scanner has been performed. Bone was represented by layers aluminum linearly increasing thickness which were scanned under water thicknesses ranging from 0 to 25 cm represent different body soft tissue. Beam had two measured BMD: (i) at constant true BMD, BMD varied thickness; (ii) thickness, not precisely linear. For conditions appropriate hip studies (BMD values range 0.7 1.4 g/cm2 between 15 cm) maximum deviation linear 0.023 g/cm2, while root‐mean‐square (0.01 g/cm2) comparable precision or femoral neck scan (about 1%). The largest departures linearity found occur thinnest 0.2 0.6 g/cm2. effect nonlinearity results longitudinal examined: 20‐cm changes slightly overestimated change implied an 0.15%/year rate loss 3%/year postmenopausal woman.