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This patient education pageprovides general informationconcerning the radiologic sci-ences. The ASRT suggests thatyou consult your physician forspecific information concern-ing your imaging exam andmedical condition. Health careprofessionals may reproduce thesepages for noncommercial educa-tional purposes. Reproduction forother reasons is subject to ASRTapproval.

For more information,contact the American Societyof Radiologic Technologists,15000 Central Ave. SE,Albuquerque, NM87123-3909,or visit us online atUJWW. asrt. arg.

PATIENT PAGE

Bone DensitometryBone densitometry is a type of imaging

examination that measures your bone min-eral density,which is a sign of bone strength.Bones that are not very dense become brit-tle and weak and are more likely to break. Anumber of conditions cause a loss of bonemass, such as osteoporosis, some inheriteddiseases or treatments for chronic diseases.Because postmenopausal women are athigher risk for osteoporosis, the NationalOsteoporosis Foundation recommends thatwomen older than 65 undergo a bone den-sitometry test every 2 years.

Several imaging techniques can be usedto measure bone density, including ultra-sound and computed tomography, but the

most com-monmethodis dual-energyx-rayabsorp-tiometry, orDXA.DXA,pronounced"dexa,' usesx-raystoanalyze theamount ofbone yourskeleton has.

During aDXAscan,density mea-surementsare taken of

bones at specific areas of your body.Thosemeasurements then are compared to a data-base of "normal" individuals of your sameage, sex and race. The results showwhetheryou have lost bone density.

The measurements also help determinethe presence of osteoporosis and can beused to estimate your risk of bone fracture.If you are being treated for bone loss, afollow-up DXA scan can show if the thera-py is working.

Patient PreparationBefore your examination, a radiographer

willexplain the procedure to you and answerany questions you might have. A radiogra-pher, also known as a radiologic technolo-gist, is a skilled medical professional who has

RADIOLOGIC TECHNOLOGY March/April 2007, Vol. 78/No. 4

DXA scan. Image courtesy GE Medical Systems/Lunar,Milwaukee, Wis.

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received specialized education in the areasof radiation protection, patient care, radia-tion exposure, radiographic positioning andradiographic procedures.

The radiographer will ask you severalquestions about your medical history. It ishelpful to have a list of current medicationsand dosages you are taking. The radiogra-pher also may ask you if you are on hor-mone replacement therapy or you have hadrecent medical imaging examinations suchas an upper GI selies.

Usually, you will be allowed to remainin your street clothes during the examina-tion, although some facilities may requireyou to put on a hospital gown. Avoidwearing clothing with metal zippers,buckles, buttons or other metallic objectsbecause they can affect the bone densitymeasurement. It is a good idea to wear acomfortable, 2-piece outfit such as a sweatsuit because for many measurements youwill be lying on your back on an examina-tion table.

During the ExaminationThe radiologic technologist willposi-

tion you on a padded table and ask you toremain as still as possible during the test.The technologist then willuse the DXAequipment to scan one or more areas ofbone - usually the lower back, hip, wrist orforearm. The DXA exam does not hurt, andyou will not feel anything when the x-rayspass through your body. The exam takesabout 15 to 20 minutes.

Postexamination InformationThe DXA scanner computes a numerical

reading of bone strength, called aT-score,that is used to compare your bone densitywith established values.

Your physician will receive a report ofthe DXA findings. He or she then willadvise you of the results and discuss whatfurther procedures, if any, are needed.If you have low bone density, you may beadvised to take calcium supplements orother medication. Your physician also mayrecommend that you participate in somekind of weight-bearing exercise, such aswalking, to strengthen your bones. •

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