"Dual energy X-ray absorptiometry (DEXA) is a painless and quick test to detect bone loss. This test, which uses a very low-dose radiation X-ray, is so accurate that it is considered the “gold standard” of all the available bone mineral density tests. Even if you have bone loss of less than 2%, DEXA can detect it.

DEXA uses radiation of less than 1/20th of a standard chest X-ray to establish the bone density of the spine, hip or wrist. A computer translates your bone mineral density into a number that can be compared to the peak bone density for your gender, height and weight. It can also be compared to DEXA tests done later to determine the rate of bone loss.

Osteoporosis, a disease that reduces the strength of your bones causing them to become brittle, lighter and considerably more prone to fractures, affects more than 20 million women and 5 million men in the United States. It used to be that osteoporosis went undiagnosed, progressing silently over the years, until a fracture occurred. With the development of DEXA, early diagnosis is possible and fractures associated with this disease can be prevented. Early diagnosis with the use of DEXA and other bone density tests have given physicians new tools not only to identify, but to treat and overcome osteoporosis."

https://www.chifranciscan.org/health-care-services/diagnostic-imaging-radiology-services/dexa-bone-density-scan.html