Change of the fractal dimension according to the decalcification degree and the exposure time in the bovine rib

We evaluated the fractal dimension change on bovine rib radiographs according to the decalcification degree and the exposure time in the bovine rib. Twenty 5 mm thick cross-sectional blocks from bovine rib bone were progressively decalcified in 30 mL 0.1 N hydrochloric acid for 5, 30, and 90 minutes. They were radiographed at three exposure time settings (0.22, 0.36, 0.43 mAs) before and after each decalcification stage. We selected 100 X 100 pixel-sized regions of interests (ROIs) on trabecular bone and calculated fractal dimensions by box-counting method. Repeated measures ANOVA showed that fractal dimensions gradually decreased after acid-induced demineralization and with more exposure(P<0.001). The fact that fractal dimensions decrease after decalcification might support the hypothesis that patients with osteoporosis have decreased radiographic fractal dimension in trabecular bone in comparison to normal subjects