NB: If there is a possibility that the patient might be pregnant the DEXA Department must be made aware of this as soon as possible and when applicable, in advance of the appointment.
Only adults are scanned, patients under 18 must be referred to Southampton General Hospital.
DEXA/Bone Density scans are used solely for the purpose of diagnosing osteoporosis. This occurs when the body loses too much bone, resulting in the bone becoming weak and prone to fracture. This tends to be predominantly a problem in older women, but can also affect men and younger people with certain diseases such as anorexia, or some drug therapies such as hormone suppressants or steroids. Over a lifetime 50% of women and 20% of men will be diagnosed with osteoporosis.
The scan is painless, non-invasive and very safe. Although X-rays are used, the level of radiation is very small, roughly equivalent to the amount received taking a transatlantic flight.
The areas scanned are usually the lumbar spine and one of the hips, as these are the areas that have the highest rate of osteoporotic fractures. The patient lies on the table and the scanner moves very slowly over the patient. The patient is not enclosed in the scanner, so patients with claustrophobia have no need for concern. All patients are asked to remove all metal from their clothing, including bra clips and zips, as the scanner cannot distinguish between metal and bone and the results would be futile, requiring a repeat scan. The whole process takes approximately 20 minutes.
The resulting images are very "grainy" and quite unsuitable for conventional diagnosis due to the low level of radiation used to produce them. Using these images a computer algorithm calculates the patient's T-score. A score of between 1 and -1 is in the normal range, between -1 and -2.5 indicates reduced bone density and is called osteopenia, whilst scores below -2.5 are classified as osteoporosis.
Early diagnosis is crucial as drug treatment can be very effective and prevents subsequent loss of mobility and pain. If left untreated the result can be multiple fractures. All patients over 50 with a low trauma fracture should be scanned, as well as those on hormone suppressants and steroids.
