A 67-year-old woman suffers from back and hip

pain. Physical examination reveals that she has a slightly stooped posture and

is slightly shorter than she was a few years ago. The patient is most likely

suffering from osteoporosis, which particularly affects postmenopausal women.

To confirm this, a bone density measurement, called densitometry, is performed

using X-rays. What should the measured bone density be to confirm osteoporosis?