A measure of the amount of minerals (mostly calcium and phosphorous) contained in a certain volume of bone. Bone mineral density measurements are used to diagnose osteoporosis (a condition marked by decreased bone mass), to see how well osteoporosis treatments are working, and to predict how likely the bones are to break. Low bone mineral density can occur in patients treated for cancer. A bone mineral density scan is an imaging test that measures bone density (the amount of bone mineral contained in a certain volume of bone) by passing x-rays with two different energy levels through the bone through an area of the body such as the hip, hand, or foot for signs of mineral loss and bone thinning. It is used to diagnose osteoporosis (decrease in bone mass and density). Also called DEXA scan, BMD scan, dual energy x-ray absorptiometric scan, dual x-ray absorptiometry, DXA, and DEXA.