The general X-ray film can be taken to observe the sparseness and regularity of the bone trabeculae within the bone, and also to observe the thickness and density of the bone cortex to infer the bone density, but it cannot make a qualitative and quantitative diagnosis directly. If the bone trabeculae are arranged closely and regularly, there is no problem with the density of bone. If the trabeculae are sparsely arranged, or even disorganized or missing, it often indicates insufficient bone density. When observing the bone cortex, if the cortex is thicker and the density is higher, it can be presumed that the bone density is not a problem. If the bone cortex is seen to be thinner and less dense, it can be indirectly presumed that there may be bone loss. Formal observation of bone density is now taken by dual-energy X-ray absorption method, thus making qualitative and quantitative examination.