Ultrasound is used to estimate bone density and fracture risk. In the US, only units that measure at the heel are approved for use. These devices assess the speed of sound and do not use any radiation. You may see these machines used at health fairs, health food stores, drugstores, or in your doctors’ offices… Read more
Ultraviolet radiation
Sunshine is the main source for vitamin D. Sun’s rays produces three types of ultraviolet (UV) radiation: UVA, UVB, and UVC. Both UVA and UVB reach the Earth’s surface. Short exposure to UVB starts the cascade of events that produces vitamin D. However, too much exposure to UVB and UVA may lead to skin cancers… Read more