DEXA is an acronym for Dual Energy Absortiometry. This painless test measures bone mineral density in patients at risk for osteoporosis by directing low doses of x-ray energy from two different sources toward the patient's bone. Each x-ray beam has a distinct energy peak or signature. Tissue absorbs one of the beams and the bone absorbs the other energy beam. Then the scanner can read the different levels of absorption and uses special software to measure the bone mineral density, which is an indicator of bone strength.
The hip and spine are the usual areas for the scan but fingers, hands, forearms or even the foot provide suitable readings as well. To perform the scan, the patient lies down on a table. Below the table is an x-ray generator and above the table is an imaging device. The imaging device passes over an area of the body and generates an image on a monitor.
Images of the spine require the patient to elevate her legs by resting both legs on a support pad. This position causes the pelvis and lower spine to flatten, allowing for a clearer image. Images of the hip involve placing the patient's foot in a brace or holder and rotating the foot inward. In both cases, it is necessary to lie still while the image is generating.
There is minimal preparation for this test which is usually performed on an outpatient basis. Patients should wear loose, comfortable clothing and refrain from taking calcium supplements for 24 to 48 hours. Avoid wearing jewelry or other metals and tell the technician about any back or hip injuries you may have had in the past. You will complete a questionnaire that will help determine your risk for osteoporosis and should let the technician know if you have had recent CT scans or x-rays involving barium. Although the radiation exposure is minimal, it is important to let the physician know if there is any possibility that you are pregnant.
The DEXA scan is a useful tool for assessing bone strength and, when used with other tools such as patient history and scan comparisons, helps predict a patient's risk for fracture. Once the test is completed, a radiologist will analyze the images and send a report to your physician. Your physician will consider the DEXA results along with your family and personal medical history and discuss the results with you.
Tags: bone mineral, bone mineral density, bone strength, imaging device, mineral density
