Bone Density Test is also called Dual-Emission X-ray Absorptiometry (DEXA) which uses two different energy levels of X-ray beam to scan the human spine, hip or the whole body to calculate the bone density. Due to the different X-ray absorbability of various regions of bones, one’s bone density can therefore be calculated. Compared to other bone density examinations, DEXA is relatively fast, accurate and the radiation dose to patients is extremely low (it is equivalent to 1/10 of a chest x-ray). DEXA is widely accepted for diagnostic purposes.