Dual- Energy X-ray Absorptiometry (DEXA)

Last updated: February 8, 2026Reviewed date: February 8, 2026Reading time: 8 min read
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Dual-energy x-ray absorptiometry (DEXA) has sustained a niche for measuring bone mineral density since its approval by the Food and Drug Administration (FDA) for clinical use in 1988. The Bone Mass Measurements act in 1998 solidified its validity in light of other diagnostic modalities such...

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বাংলা রোগী নোট এখনো যোগ করা হয়নি। পোস্ট এডিটরে “RX Bangla Patient Mode” বক্স থেকে সহজ বাংলা সারাংশ যোগ করুন।

এই তথ্য শিক্ষা ও সচেতনতার জন্য। এটি ডাক্তারি পরীক্ষা, রোগ নির্ণয় বা প্রেসক্রিপশনের বিকল্প নয়।

Article Summary

Dual-energy x-ray absorptiometry (DEXA) has sustained a niche for measuring bone mineral density since its approval by the Food and Drug Administration (FDA) for clinical use in 1988. The Bone Mass Measurements act in 1998 solidified its validity in light of other diagnostic modalities such as chemical analysis, direct dissection and ashing, quantitative ultrasonography, and later on against CT/MRI images. DEXA is comparatively inexpensive with...

Key Takeaways

  • This article explains Anatomy and Physiology in simple medical language.
  • This article explains Indications of Dual-energy x-ray absorptiometry (DEXA) in simple medical language.
  • This article explains Contraindications in simple medical language.
  • This article explains Equipment in simple medical language.
Educational health guideWritten for patient understanding and clinical awareness.
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Seek urgent medical care if you notice

These warning signs are general safety guidance. Local emergency numbers and clinical judgment should always come first.

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  • Any symptom that feels urgent, unusual, or unsafe for the patient.
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See a doctor

Book a professional medical evaluation if symptoms persist, worsen, recur often, affect daily activities, or occur in a high-risk patient.

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Dual-energy x-ray absorptiometry (DEXA) has sustained a niche for measuring bone mineral density since its approval by the Food and Drug Administration (FDA) for clinical use in 1988. The Bone Mass Measurements act in 1998 solidified its validity in light of other diagnostic modalities such as chemical analysis, direct dissection and ashing, quantitative ultrasonography, and later on against CT/MRI images. DEXA is comparatively inexpensive with notably shorter scan times and radiation exposure compared to other imaging options, and there is a long-standing consensus regarding guidelines for interpreting DEXA images.

Three-dimensional (3D) C-arm computed tomography is a new and innovative imaging technique. It uses two-dimensional (2D) X-ray projections acquired with a flat-panel detector C-arm angiography system to generate CT-like images. To this end, the C-arm system performs a sweep around the patient, acquiring up to several hundred 2D views. They serve as input for 3D cone-beam reconstruction. Resulting voxel data sets can be visualized either as cross-sectional images or as 3D data sets using different volume rendering techniques. Initially targeted at 3D high-contrast neurovascular applications, 3D C-arm imaging has been continuously improved over the years and is now capable of providing CT-like soft-tissue image quality. In combination with 2D fluoroscopic or radiographic imaging, information provided by 3D C-arm imaging can be valuable for therapy planning, guidance, and outcome assessment all in the interventional suite.

A C-arm with the x-ray source below the supine patient emits photons at two distinct energy levels specific for soft tissue and cortical bone. A collimator is situated between the patient and x-ray source to minimize scatter. The attenuations from these low and high-energy photon emissions are detected above the patient and are combined to create a planar image to assess bone mass per unit volume (g/cm), for example, bone mineral density (BMD). A T-score is a number of standard deviations between the patient’s mean BMD and the mean of the population compared with reference populations matched in gender and race. The Z-score is the number of standard deviations above or below the mean of age-matched controls.

Anatomy and Physiology

Lumbar Spine
  • To flatten the lordosis of the lumbar spine, the patient lays supine with their hips and knees flexed on a supportive cushion. A PA film should display the spine as straight as possible as well as display the visible superior margin of bilateral iliac crests and the central portion of the T12/L5 vertebral body. Bone mineral density measurements are obtained using the L1 through L4 vertebral bodies.
Hip
  • The long axis of the femoral diaphysis is aligned with the scanner as the patient lies supine and a positioning device which internally rotates the femur to elongate the femoral neck on the PA image. If the femur is effectively internally rotated the less trochanter should be barely, if at all, visible. Bone mineral density measurements are obtained using the femoral neck, greater trochanter, Ward’s area, intertrochanteric region, and total hip.
Forearm
  • The patient’s non-dominant arm is placed on the table with the forearm pronated, and the image should demonstrate the distal cortex of the radius/ulna and the diaphysis of each aligned with the long axis of the image. Bone mineral density measurements are obtained using the mid to distal radius and ulna.
Whole Body
  • The patient is placed supine on the table with arms pronated and feet in dorsiflexion. Bone mineral density measurements are obtained using the upper/lower extremities and the head.
Choosing the Site to Scan
  • Two sites are routinely evaluated with DEXA: the lumbar spine and hip.[rx]

Indications of Dual-energy x-ray absorptiometry (DEXA)

All women 65 years and older and men 70 years and older for asymptomatic screening.

Women younger than 65 years old at risk for fracture risk. সহজ বাংলা: হাড় দুর্বল হয়ে ভাঙার ঝুঁকি বেশি।" data-rx-term="osteoporosis" data-rx-definition="Osteoporosis means weak, fragile bones with higher fracture risk. সহজ বাংলা: হাড় দুর্বল হয়ে ভাঙার ঝুঁকি বেশি।">osteoporosis:

  • Estrogen deficiency
  • History of maternal hip fracture before the age of 50
  • Low body mass (less than 127 pounds)
  • History of amenorrhea more than 1 years before the age of 42

Women younger than 65 years old or men younger than 70 years old with the following risk factors:

  • Current cigarette smoker
  • Loss of height
  • Thoracic Kyphosis

Individuals at any age with bone mass osteopenia or fragility fractures on imaging studies

Individuals 50 years and older who develop wrist, hip, spine, or proximal humerus fracture with minimal or no trauma, excluding pathologic fractures. People of any age who develop one or more insufficiency fractures.

Individuals receiving (or expected to receive) glucocorticoid therapy equivalent to > or = to 5mg of prednisone or equivalent per day for > or = 3 months. Individuals beginning or receiving long-term therapy with medications known to affect BMD adversely:

  • Anticonvulsants
  • Androgen deprivation therapy
  • Aromatase inhibitor therapy
  • Chronic heparin

Individuals with an endocrine disorder known to affect BMD adversely

  • Hyperparathyroidism
  • thyroid gland makes too much hormone. সহজ বাংলা: থাইরয়েড হরমোন বেশি।" data-rx-term="hyperthyroidism" data-rx-definition="Hyperthyroidism means the thyroid gland makes too much hormone. সহজ বাংলা: থাইরয়েড হরমোন বেশি।">Hyperthyroidism
  • Cushing’s syndrome

Hypogonadal men 18 years and older and men with surgically or chemotherapeutically induced castration

Individuals with medical conditions that could alter BMD:
  • Chronic renal failure
  • pain, swelling, stiffness, or reduced movement. সহজ বাংলা: জয়েন্টের প্রদাহ।" data-rx-term="arthritis" data-rx-definition="Arthritis means joint inflammation causing pain, swelling, stiffness, or reduced movement. সহজ বাংলা: জয়েন্টের প্রদাহ।">arthritis: Rheumatoid arthritis is an autoimmune joint disease causing infection, or irritation, often causing pain, swelling, heat, or redness. সহজ বাংলা: শরীরের প্রদাহ; ব্যথা, ফোলা বা লালভাব হতে পারে।" data-rx-term="inflammation" data-rx-definition="Inflammation is the body’s response to injury, infection, or irritation, often causing pain, swelling, heat, or redness. সহজ বাংলা: শরীরের প্রদাহ; ব্যথা, ফোলা বা লালভাব হতে পারে।">inflammation, pain, and swelling. সহজ বাংলা: রোগপ্রতিরোধ ব্যবস্থার ভুল আক্রমণে জয়েন্টের প্রদাহ।" data-rx-term="rheumatoid arthritis" data-rx-definition="Rheumatoid arthritis is an autoimmune joint disease causing inflammation, pain, and swelling. সহজ বাংলা: রোগপ্রতিরোধ ব্যবস্থার ভুল আক্রমণে জয়েন্টের প্রদাহ।">Rheumatoid arthritis and other inflammatory arthritides
  • Eating disorders, including anorexia nervosa and bulimia
  • Organ transplantation
  • Prolonged immobilization
  • Conditions associated with secondary fracture risk. সহজ বাংলা: হাড় দুর্বল হয়ে ভাঙার ঝুঁকি বেশি।" data-rx-term="osteoporosis" data-rx-definition="Osteoporosis means weak, fragile bones with higher fracture risk. সহজ বাংলা: হাড় দুর্বল হয়ে ভাঙার ঝুঁকি বেশি।">osteoporosis, such as gastrointestinal malabsorption or malnutrition, sprue, osteomalacia, vitamin D deficiency, endometriosis, acromegaly, chronic alcoholism or established cirrhosis, and multiple myeloma
  • Individuals who have had a gastric bypass for obesity (The accuracy of DEXA in these patients might be affected by obesity)

Individuals considering pharmacologic therapy for fracture risk. সহজ বাংলা: হাড় দুর্বল হয়ে ভাঙার ঝুঁকি বেশি।" data-rx-term="osteoporosis" data-rx-definition="Osteoporosis means weak, fragile bones with higher fracture risk. সহজ বাংলা: হাড় দুর্বল হয়ে ভাঙার ঝুঁকি বেশি।">osteoporosis. Individuals monitored for:

  • Assess the effectiveness of fracture risk. সহজ বাংলা: হাড় দুর্বল হয়ে ভাঙার ঝুঁকি বেশি।" data-rx-term="osteoporosis" data-rx-definition="Osteoporosis means weak, fragile bones with higher fracture risk. সহজ বাংলা: হাড় দুর্বল হয়ে ভাঙার ঝুঁকি বেশি।">osteoporosis drug therapy
  • Follow-up medical conditions associated with abnormal BMD.

Children or adolescents with medical conditions associated with abnormal BMD including but not limited to:

  • Individuals receiving (or expected to receive) glucocorticoid therapy for more than 3 months
  • Individuals receiving radiation or chemotherapy for malignancies
  • Individuals with an endocrine disorder known to adversely affect BMD (e.g., hyperparathyroidism, hyperthyroidism, growth hormone deficiency or Cushing’s syndrome)
  • Individuals with bone dysplasias known to have excessive fracture risk (osteogenesis imperfecta, osteopetrosis) or high bone density
Individuals with medical conditions that could change BMD, for example
  • Chronic renal failure
  • Rheumatoid arthritis and other inflammatory arthritides
  • Eating disorders, including anorexia nervosa and bulimia
  • Organ transplantation
  •  Prolonged immobilization
  •  Conditions associated with secondary osteoporosis, such as gastrointestinal malabsorption, sprue, inflammatory bowel disease, malnutrition, osteomalacia, vitamin D deficiency, acromegaly, cirrhosis, HIV infection, prolonged exposure to fluorides

DEXA may be indicated in the diagnosis, staging, and follow-up of individuals with conditions that result in pathologically increased BMD, such as osteopetrosis or prolonged exposure to fluoride.

DEXA may be indicated as a tool to measure regional and whole-body fat and lean mass (patients with malabsorption, cancer, or eating disorders).

Contraindications

There are no absolute contraindications to performing DEXA.

Possibly of limited value or require modification of the technique or rescheduling of the examination in some situations, including:

  • Recently administered gastrointestinal contrast or radionuclides
  • Pregnancy
  • Severe degenerative changes or fracture deformity in the measurement area
  • Implants, hardware, devices, or other foreign material in the measurement area
  • The patient’s inability to attain correct position and/or remain motionless for the measurement
  • Extremes of high or low body mass index (BMI) which may adversely affect the ability to obtain accurate and precise measurements. Quantitative computed tomography (QCT) may be a desirable alternative in these individuals.
  • Any condition that precludes proper positioning of the patient to be able to obtain accurate BMD values

Equipment

A C-arm with x-ray source allowing for variable photon energy levels, collimator, detector, and associated computer software.

Personnel

Radiologic/nuclear medicine technologist under the supervision of a licensed physician.

Preparation

Pre-Scan Discussion
  • Patients can tolerate laying on back for up to 10 minutes.
  • If the patient is greater than 300 pounds, they will require alternative BMD testing. Different models have different weight restrictions, and the system owner’s manual should be checked.
  • Recent medical imaging with contrast, such as barium or gadolinium, will preclude imaging 2 weeks after contrast was administered
  • Premenopausal patients should be asked whether there is any possibility that they might be pregnant. A pregnancy test may need to be administered before the examination.
  • Calcium tablets should not be taken in the 24 hours before the examination
  • Patients should wear comfortable, loose-fitting clothes with avoidance of metal components such as zippers.
  • If prior DEXA was done, the patient should be instructed to bring results.
  • For body composition studies, patients should be scanned in the morning after a 12-hour overnight fast for consistency.
Examination Day Discussion
  • Confirm they have complied with the recommendations listed above
  • The menopausal status should be re-checked and whether a pregnancy test or question relating to possible pregnancy has been administered
  • Subjects should be dressed in a hospital gown or scrubs, wearing only underpants and, if necessary, thin socks. A thin sheet may be placed over subjects for warmth.
  • All radio-opaque objects should be removed from the scan area.

Technique of Dual-energy x-ray absorptiometry (DEXA)

A licensed radiologist interprets the scans and a T-score is determined to evaluate the standard deviation in the mean from the reference population and patient’s average bone mineral density. The World Health Organization (WHO) defines T-scores as:

  • Greater than or equal to -1.0: normal
  • Less than -1.0 to greater than -2.5: osteopenia
  • Less than or equal to -2.5: osteoporosis
  • Less than or equal to -2.5 plus fragility fracture: severe osteoporosis

Complications

  • No complications considered due to procedure.
  • The radiation dose is comparable to standard background radiation.

References

Doctor visit helper

Prepare before seeing a doctor

A simple rural-patient checklist to help you explain symptoms clearly, ask better questions, and avoid unsafe self-treatment.

Safety note: This is not a prescription or diagnosis. For severe symptoms, pregnancy danger signs, children with serious illness, chest pain, breathing difficulty, stroke-like weakness, or major injury, seek urgent care.

Which doctor may help?

Start with a registered doctor or the nearest qualified health center.

What to tell the doctor

  • Write when the problem started and how it changed.
  • Bring old prescriptions, investigation reports, and current medicines.
  • Write allergies, pregnancy status, diabetes, kidney/liver disease, and major past illnesses.
  • Bring one family member if the patient is weak, elderly, confused, or a child.

Questions to ask

  • What is the most likely cause of my symptoms?
  • Which danger signs mean I should go to hospital quickly?
  • Which tests are necessary now, and which can wait?
  • How should I take medicines safely and what side effects should I watch for?
  • When should I come for follow-up?

Tests to discuss

  • Vital signs: temperature, pulse, blood pressure, oxygen saturation
  • Basic physical examination by a clinician
  • CBC, urine test, blood sugar, or imaging only when clinically needed

Avoid these mistakes

  • Do not use antibiotics, steroid tablets/injections, or strong painkillers without proper medical advice.
  • Do not hide pregnancy, kidney disease, ulcer, allergy, or blood thinner use.
  • Do not delay emergency care when danger signs are present.

Medicine safety and first-aid guide

This section is for patient education only. It does not replace a doctor, pharmacist, or emergency care.

Safe first steps

  • Avoid heavy lifting, sudden bending, and prolonged bed rest.
  • Use comfortable posture and gentle movement as tolerated.
  • Discuss physiotherapy, X-ray, or MRI only when clinically needed.

OTC medicine safety

  • For mild back pain, pain-relief medicine may be discussed with a doctor or pharmacist.
  • Avoid repeated painkiller use if you have kidney disease, stomach ulcer, uncontrolled blood pressure, or are taking blood thinners.

Avoid these mistakes

  • Do not start antibiotics without a proper medical decision.
  • Do not use steroid tablets or injections casually for quick relief.
  • Do not delay emergency care because of home remedies.

Get urgent help if

  • Back pain with leg weakness, numbness around private area, loss of urine/stool control, fever, cancer history, or major injury needs urgent care.
Medicine names, dose, and timing must be decided by a qualified clinician or pharmacist after checking age, pregnancy, allergy, other diseases, and current medicines.

For rural patients and family caregivers

Patient health record and symptom diary

Write your symptoms, medicines already taken, test results, and questions before visiting a doctor. This note stays on your device unless you print or copy it.

Doctor to discuss: Orthopedic / spine specialist, physical medicine doctor, or qualified clinician
Tests to discuss with doctor
  • Neurological examination for leg power, sensation, reflexes, and straight leg raise
  • X-ray only if injury, deformity, long-lasting pain, or doctor suspects bone problem
  • MRI discussion if severe nerve symptoms, weakness, bladder/bowel problem, or persistent symptoms
Questions to ask
  • What is the most likely cause of my symptoms?
  • Which warning signs mean I should go to emergency care?
  • Which tests are really needed now?
  • Which medicines are safe for my age, pregnancy status, allergy, kidney/liver/stomach condition, and current medicines?
  • Is physiotherapy, posture correction, or activity modification needed?

Emergency warning signs such as chest pain, severe breathing difficulty, sudden weakness, confusion, severe dehydration, major injury, or loss of bladder/bowel control need urgent medical care. Do not wait for online information.

Safe pathway to proper treatment

Care roadmap for: Dual- Energy X-ray Absorptiometry (DEXA)

Use this simple roadmap to understand the next safe steps. It is educational and does not replace examination by a doctor.

Go to emergency care if you notice:
  • Severe or rapidly worsening symptoms
  • Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration
Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.
  1. Step 1

    Check danger signs first

    If danger signs are present, seek emergency care and do not wait for online information.

  2. Step 2

    Record the symptom story

    Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.

  3. Step 3

    Visit a qualified clinician

    A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.

  4. Step 4

    Do only useful tests

    Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.

  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips
  • Take a written symptom diary and all previous prescriptions/test reports.
  • Do not hide medicines already taken, even herbal or over-the-counter medicines.
  • Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.

RX Patient Help

Ask a health question safely

Write your symptom story. A health professional or site editor can review it before any answer is prepared. This box is not for emergency care.

Emergency first: Severe chest pain, breathing trouble, unconsciousness, stroke signs, severe injury, heavy bleeding, or rapidly worsening symptoms need urgent local medical care now.

Frequently Asked Questions

Is this article a replacement for a doctor?

No. It is educational content only. Patients should consult a qualified clinician for diagnosis and treatment.

When should I seek urgent care?

Seek urgent care for severe symptoms, rapidly worsening condition, breathing difficulty, severe pain, neurological changes, or any emergency warning sign.

References

Add references, clinical guidelines, textbooks, journal articles, or trusted medical sources here. You can edit this area from the RX Article Professional Blocks panel.

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