DEXA Scan for Bone Density

DEXA scanning is the most frequently used and accurate method of determining bone mineral density.The bone mineral density information can be used to diagnose or assess osteoporosis and predict the risk of bone fractures. The term DEXA is an acronym which refers to Dual Energy X-ray Absorptiometry. It is often referred to as a DXA scan, bone densitometry, or simply bone density test.

A DEXA scan works by utilizing a very low level of x-rays.Two x-ray beams with different energy levels (one high and one low) are aimed at the patient’s bones. After making allowance for the soft tissue absorption of the x-rays the bone mineral density (BMD) can be determined by the amount of radiation absorbed by the bone. The actual radiation dose of the DEXA scan is very minimal and is equivalent to approximately 1/10 that of a standard chest x-ray.

The equipment will produce a report that will be interpreted by the physician.The scan report will compare the patients BMD with that of a younger normal patient and produce a score (T-score) that will give an indication of the bone mineral density.

Basically, a higher bone mineral density means that the bone is itself is denser. A higher density bone is stronger and less likely to break. Conversely, a lower BMD score indicates a weaker bone and an increased likelihood of fracture. It is important for the patient to understand that a low BMD only predicts an increased risk of fracture, and not a fracture itself.

DEXA scanning is usually done on the hips and the spine. Although osteoporosis involves the entire body, measurements taken at one site can predict the BMD of other sites as well. For patients that have had spine or hip surgery an alternative site will be chosen.

The actual scan itself takes about 20 minutes and is a very simple procedure for the patient.  The patient is advised to wear loose clothing with no buttons or zippers. The only preparation required is to refrain from taking calcium supplements for 24 – 48 hours prior to the exam.

The National Osteoporosis Foundation recommends bone density scanning for women age 65 and older and men over the age of 70. Osteoporosis is a disease which causes bones to become brittle and weak. In most cases low levels of calcium and other minerals within the bones are the major contributing factor.  Fractures are the most common and serious side effect from osteoporosis.

A DEXA Scan will indicate the presence of osteoporosis and hopefully help in reducing the likelihood of bone fractures.