Osteoporosis is one of the six frequently-occurring disease. As WHO reported, there are more then 3.8 hundred million old people which above 65 years old in the world, about 65% in these are having osteoporosis. Therefore, in 1997, the World health Organization (WHO) has designed the 24th day of June each year as International Day of Osteoporosis. As reported, there are 90 million people having different grade of the osteoporosis. Osteoporosis is the most common phenomenon in middleaged or old people. It is necessary for those people to measure the mineral of the bone. It is because the decrease of the mineral would lead to osteoporosis and fracture. Nowadays, many countries have taken the densitometer as routine medical equipment.
Dual energy X-ray densitometer transforms single energy peaks into dual energy peaks by fixing an absorbing plate of rare earth elements above the X-ray emitted from the bulb and measures with precision the density of mineral substances in human bones, based on the mechanism that when the rays with different amount of energy pass through parenchyma and bone, their exponential damping will decline in different degree, resulting in a faded image of energy. It can determine the bone density in any part of human body, offering an objective judgment and basis for the early mass survey and the curative effect of prevention and cure in regard with the osteoporosis. Currently, all densitometers in our country are single-photon densitometers. They use single photon as their signal source. The shortages in this kind of device: difficult to position and not accurate. Dual photon or dual energy densitometer can overcome these shortages. It has been widely used in many developed countries for its advanced characteristics of accurate, short time, low does and middle price.