Cross calibration of DEXA by using European spine phantom

Abstract

Osteoporosis is a disease characterized by low bone mass and micro-architecturaldegradation of bone tissue, leading to enhanced bone fragility and a consequent increase infracture risk. Among many risk factors for osteoporosis, bone mineral density (BMD) measured by dual energy X-ray absorptiometry (DEXA) scanners is the most acceptedpredictor of osteoporotic fractures. The World Health Organization (WHO) also uses BMDto define osteoporosis. As a result, BMD is an important risk factor, and among otherthings, has been used in the diagnosis of the disease, selection of treatment strategy, and evaluation of treatment efficacy.Since DXA technology has become widely acceptable and available as a screening toolfor osteoporosis, standardization of BMD values and calibration among scanners areimportant objectives for the osteoporosis community. In this study we scanned 28 densitometers with one ESP (s.n. 03-208) and calculated the accuracy of each densitometerand observed the variation among different models and manufacturers.We calculated cross-calibration formulas by linear regression analysis for differentmodels of 4 main manufacturers. When we calculate the MSE (Mean Squared Error) between the original values measured on the densitometers and the calculated with crosscalibration formulas we found maximum error of 0.0042.With the BMD measurements obtained by each densitometer the reproducibility of thedevice are observed. And as a high lightening result, 27.74% of the total BMD values obtained from the device are out of reproducibility acceptance range of ±1.5% of the mean.|Keywords: Spine phantom, cross calibration, DEXA