Dual energy X-ray absorptiometry is a special form of X-ray that is used specifically to measure bone loss. It compares the results of two X-ray scans at different energy levels to determine the bone mass of the subject. Early uses of X-ray equipment to measure bone density were inadequate, typically only showing when the percentage of bone loss had already reached 30 to 40%. The first potential replacements were single photon and dual photon absorptiometry. However these technologies were replaced by DEXA when it was introduced in 1986 because DEXA was faster, more precise, and minimized radiation exposure to both the subject and the operator.
DEXA (dual-energy x-ray absorptiometry), Also known as Bone Densitometry, Overview
How DEXA Works
The DEXA test basically uses X-rays to measure bone density. However, instead of a single frequency or energy level, two pulses, one high energy and one lower energy are used. The higher energy pulse maps the bone structure, while the lower energy measures the soft tissue. A computer calculates the difference and produces a result that accurately shows the bone density and bone loss.
Medical Uses of DEXA
The primary use of the DEXA test is to measure for loss of bone mass or density. It is used to detect and aid in treatment of osteoporosis and osteopenia. DEXA imaging can also be used to measure body fat and lean body mass. Your doctor may recommend the test based on age, patient or family history, or after fractures or other injuries. Other types of imaging tests do not provide near the same accuracy for this specific use.
Potential Hazards of Using DEXA
DEXA imaging uses X-rays which include a very low level of risk of cancer. The risk is higher in very young children or during pregnancy. In general the medical benefits far outweigh the risks. The process is also painless.
Crown Valley Imaging located in Orange County has two imaging centers in Mission Viejo and Newport Beach where you can have DEXA exams performed by qualified technologists at the Mission Viejo office. Images are read and interpreted by Board Certified Neuroradiologists and Board Certified Musculoskeletal Radiologists and reports are generated within 24-48 business hours.