Evaluation of CT-DEA performance on Ca/P ratio assessment in bone apatite using EDX

The aim of this study is to evaluate the performance of a new computed tomography-dual energy analysis (CT-DEA) technique developed for the non-invasive assessment of the 3D spatial distribution of calcium/phosphorus (Ca/P) ratio in bone. For this, the Ca/P ratio in 58 regions from four healthy and four inflammation-mediated osteoporotic (IMO) rabbit bone collagen-free samples were assessed using energy dispersive X-ray spectroscopy (EDX) and CT-DEA. Image registration, performed using NifTK software (Centre for Medical Imaging Computing, University College London), allowed the comparison with the results from the two imaging systems. A value of R-2 = 0.69 in the fit of CT-DEA Ca/P ratio versus EDX Ca/P ratio and a mean absolute/percentage difference of 0.11 +/- 0.08/8 +/- 6% in the CT-DEA Ca/P ratio from the EDX results suggest sufficient confidence in the current experimental capabilities of the developed technique. The main difficulties in the comparison of the results using the two techniques and possible sources of error are discussed. Even though there are still possible improvements that can be made in the developed technique, through this study, it has been shown that CT-DEA can provide valuable 3D, non-invasive information on the comparison between healthy and osteoporotic bone. (C) 2014 The Authors. X-Ray Spectrometry published by John Wiley & Sons, Ltd.