Human: My doctor says I need to have a bone density scan. What is a bone density scan? Assistant: 
A bone density scan is an imaging test that measures the density of your bones and can help detect osteoporosis, which is a condition where the bones become weak and more likely to break. The scan uses X-rays to measure the amount of calcium in your bones, and then compares this to a normal range. If your bone density falls below the normal range, it could indicate you have osteoporosis.