I am a radiology tech, and can help with the radiation question. As far as I know, a DEXA scan is the gold standard for bone density measurements, I found some information about it and copied it below for you. I've never heard of it being diagnosed with any other method.
Basically, when it comes to radiation, what you need to do is weigh the risks of the procedure vs. the benefits you will get from it. A DEXA scan will give you an accurate measurement of your bone density, and will allow doctors to help you with appropriate treatments if needed. Without it, there's no way to tell and you could be losing time in which you could have had treatments. You get radiation every day from your surroundings, cosmic radiation from the sun and outer space, radon gas from the ground, etc. So medical radiation is really only a small percentage of any radiation you receive in your lifetime--you get more radiation from flying than you do from an xray. DEXA uses a very low dose of radiation, less than regular xrays, and way less than a CT for example. There has also never been a
proven link between radiation and cancer.
What are the benefits vs. risks?
Benefits
•DXA bone densitometry is a simple, quick and noninvasive procedure.
•No anesthesia is required.
•The amount of radiation used is extremely small—less than one-tenth the dose of a standard chest x-ray, and less than a day's exposure to natural radiation.
•DXA bone density testing is the most accurate method available for the diagnosis of osteoporosis and is also considered an accurate estimator of fracture risk.
•DXA equipment is widely available making DXA bone densitometry testing convenient for patients and physicians alike.
•No radiation remains in a patient's body after an x-ray examination.
•X-rays usually have no side effects in the diagnostic range.
Risks
•There is always a slight chance of cancer from excessive exposure to radiation. However, the benefit of an accurate diagnosis far outweighs the risk.
•Women should always inform their physician or x-ray technologist if there is any possibility that they are pregnant. See the Safety page (
www.RadiologyInfo.org/en/safety/) for more information about pregnancy and x-rays.
•The effective radiation dose for this procedure varies. See the Safety page (
www.RadiologyInfo.org/en/safety/) for more information about radiation dose.
•No complications are expected with the DXA procedure.
A Word About Minimizing Radiation Exposure
Special care is taken during x-ray examinations to use the lowest radiation dose possible while producing the best images for evaluation. National and international radiology protection councils continually review and update the technique standards used by radiology professionals.
State-of-the-art x-ray systems have tightly controlled x-ray beams with significant filtration and dose control methods to minimize stray or scatter radiation. This ensures that those parts of a patient's body not being imaged receive minimal radiation exposure.
From
http://www.radiologyinfo.org/en/info.cfm?pg=dexa