Bone thickness is measured by subtracting the width of bone marrow from the entire bone width. This is done on a finger, usually, and involves very little radiation exposure. The expensive equipment and the limitation to use on bones like the fingers makes this test of limited use in diagnosing osteoporosis. Single Photon Absorotiometry . This technique is widely used in osteoporosis re search.
Bone density is measured by calculation of the amount of gamma radiation absorbed by bone.
The greater dose absorbed, the greater the bone density. Women have an eight-fold greater chance of developing osteoporosis than men. Women are usually smaller in stature than men and have less bone reserve of calcium. Women also lose the production ability of estrogen when they go through menopause. Men lose calcium from bone, but not at the high rates seen in women.