Low-Dose, Ionizing Radiation and Age-Related Changes in Skeletal Microarchitecture
Figure 2
Cancellous microarchitecture of the proximal tibial metaphysis as a function of age and radiation exposure at the time of irradiation (basal, 0 months) and 1 and 4 months after irradiation. During aging, sham-irradiated controls show relative bone volume (BV/TV) remaining constant (a), increases in tissue density (b) and trabecular thickness (Tb.Th*) (c), and declines in trabecular number (Tb.N*) (d) and connectivity density (Conn.D) (e). The ratio of trabecular rods to plates, the structure model index (SMI), remains constant with age (f). The maximum eigenvalue () of the fabric tensor increases with age (g), with the degree of anisotropy (h) remaining constant. At 1 month after irradiation, 100 cGy reduced Tb.N* by 20% (d), Conn.D by 36% (e) compared to age-matched controls. Irradiation at 100 cGy, but not at 1 cGy or 10 cGy, altered cancellous structure within 1 month in a direction and magnitude similar to 4 months of normal aging, with no further modulation between 1 and 4 months after irradiation. Mean ± SD. *Denotes for changes with IR dose (ANOVA and Tukey-Kramer posthoc compared to age-matched sham controls). #Denotes for changes with age (linear regression).
