<human>: My doctor says I need a bone density test. What is it like?
<bot>: A bone density test measures the amount of calcium in your bones. It’s done by taking x-rays of your bones and then comparing them to the bones of a healthy person of the same age, gender, and race. The results are expressed as a T score, which is a number between -1 and +2. A T score below -2.5 is considered low bone mass or osteoporosis.