Estimating the mineral density of trabecular bone using Compton scattering

Abstract

This study proposes a technique based on Compton scattering to estimate trabecular bone mineral density (TBMD), which is important for understanding bone strength, and hence, is pivotal for estimating the condition of the bone. Bone phantoms (a mixture of paraffin wax and bone powder) with various concentrations of bone ash were prepared to simulate the trabecular bone. These samples were exposed to primary gamma photon flux from a137Cs (222 GBq) radioisotope source one after the other, and the scattered photon flux was detected using an NaI(Tl) detector. The presence of the cortical bone (using aluminum sheets) and fat (tertiary butyl alcohol) around the trabecular bone was also studied to determine whether the TBMD measurements had been affected. The correlation between bone ash contents and the intensity of Compton scattering was high with a coefficient of 0.97. The outcomes suggest that TBMD is independent of the presence of the cortical bone and overlying fat, with a statistical uncertainty of ±0.3% in the count rate. The intensity of Compton scattering increased by only 1.5% when the thickness of the aluminum sheet (simulating the cortical bone) becomes was increased by four times, and by less than 5% when the bone phantom was surrounded by tertiary butyl alcohol.