Relationship between Bone Mineral Density and Body Composition Estimated by Dual-Energy X-ray Absorptiometry : Comparison between Groups Aged 20-39 and 40-59 Years

Bone mineral density (BMD) is affected by lean body mass and body weight to various degrees in the course of aging. The attempt of this study is to determine the optimal time to begin prevention of osteoporosis. In this study, female hospital employees aged 20-59 years were divided into 2 age groups, 20-39 years and 40-59 years based on age at peak BMD, and the relations of total BMD, subtotal BMD and lumbar spine BMD to lean body mass and body weight were examined in both groups. Subtotal BMD was calculated by subtracting head BMD from total BMD along with whole body measurement. While persistent positive correlations were found among all factors in the 20-39-year-old group, subtotal BMD and lumbar spine BMD were positively correlated to lean body mass in the 40-59-year-old group. Thus, lean body mass and body weight appeared to exert a profound influence on subtotal BMD in those aged 20-39 years, but lean body mass in those aged 40-59 years. Lean body mass appears to provide the best prediction of subsequent development of osteoporosis

Intensities of incident and transmitted ultraviolet-a rays through gafchromic films

Gafchromic films have been applied to X-ray dosimetry in diagnostic radiology. To correct nonuniformity errors in Gafchromic films, X-rays in the double-exposure technique can be replaced with ultraviolet (UV)-A rays. Intensities of the incident and transmitted UV-A rays were measured. However, it is unclear whether the chemical color change of Gafchromic films affects the UV-A transmission intensity. Gafchromic EBT3 films were suitable to be used in this study because non-UV protection layers are present on both sides of the film. The film is placed between UV-A ray light-emitting diodes and a probe of a UV meter. Gafchromic EBT3 films were irradiated by UV-A rays for up to 60 min. Data for analysis were obtained in the subsequent 60 min. Images from before and after UV-A irradiation were subtracted. When using 375 nm UV-A, the mean ± standard deviation (SD) of the pixel values in the subtracted image was remarkably high (11,194.15 ± 586.63). However, the UV-A transmissivity remained constant throughout the 60 min irradiation period. The mean ± SD UV-A transmission intensity was 184.48 ± 0.50 μm/cm2. Our findings demonstrate that color density changes in Gafchromic EBT3 films do not affect their UV-A transmission. Therefore, Gafchromic films were irradiated by UV-A rays as a preexposure