bone density

Bone density is a medical term referring to the amount of matter per cubic centimeter of bones. It is measured by a procedure called densitometry, often performed in the radiology or nuclear medicine departments of hospitals or clinics. The measurement is painless and non-invasive and involves minimal radiation exposure. Measurements are most commonly made over the lumbar spine and over the upper part of the hip. The forearm is scanned if either the hip or the lumbar spine can't be.
See more at Wikipedia.org...

Bone density n. A measurement corresponding to the mineral density of bone and used to diagnose osteopenia and osteoporosis. [more]Bone density - Community and Resources

Bone density is the amount of bone tissue in a certain volume of bone. It can be measured using a special x-ray called a quantitative computed tomogram.

[DEN-sih-tee]
A measure of the amount of calcium contained in a certain volume of bone. Calcium gives bones their strength and helps keep them from breaking. Bone density measurements may be used to diagnose osteoporosis, to see how well osteoporosis treatments are working, and to figure out how likely the bones are to break. Also called bone mineral density (BMD) and bone mass.