A Dual-Energy X-ray Absorptiometry (DEXA) scan is a quick, non-invasive imaging procedure used primarily to assess bone health. The test works by passing a very low dose of X-ray beams through the body to measure bone mineral density (BMD). This measurement is the standard for diagnosing osteoporosis, a condition characterized by weakened, fragile bones. A DEXA scan can also track the effectiveness of treatments aimed at slowing bone loss over time.
The Total Appointment Duration
Patients should plan for a total visit time ranging from 20 to 45 minutes. Although the actual scanning process is brief, the appointment duration accounts for necessary preparation and administrative steps. The core scan, where the imaging device passes over the body, typically takes only 5 to 15 minutes.
The majority of the appointment time is dedicated to preparation tasks, including checking in, completing paperwork, and changing into a hospital gown if required. Precise patient positioning is crucial for accurate results. For a standard central DEXA scan, the technologist carefully positions the patient on a padded table to ensure the hip and lower spine are correctly aligned for the beam. After the scan, time is needed for the patient to change back into their clothing and wrap up the visit.
Factors Influencing Scan Length
The duration of the scanning phase depends on several technical and patient-specific variables. The most significant factor is the specific anatomical site being examined. A standard central DEXA scan focuses on the hip and lumbar spine, which is the most common protocol and generally takes 10 to 15 minutes.
Scanning an additional site, like the forearm, will extend the time if the hip or spine cannot be accurately measured. A whole-body DEXA scan, often performed for body composition analysis, is a more complex procedure that takes longer than targeted bone density assessment. The generation and model of the DEXA machine also play a role, with newer equipment often completing the scans more quickly. Patient size can also influence the time needed for the scan. Proper positioning is essential for obtaining a clear image, and this process can take longer for patients who are larger or have difficulty lying still.
Preparation and Post-Scan Procedures
Patients must follow preparation guidelines to ensure the accuracy of the bone density measurement. Patients are asked to wear loose, comfortable clothing that does not contain metal, such as zippers or snaps. All metal jewelry and objects, including belts and coins, must be removed before the exam, as they interfere with the low-dose X-ray beam.
A specific dietary restriction involves calcium supplements, which should not be taken for at least 24 hours prior to the DEXA scan. Additionally, any recent medical imaging procedure that used contrast material, such as a barium exam or certain CT scans, requires a waiting period of 10 to 14 days. This waiting period is necessary because the contrast agents can interfere with the bone density readings.
Once the scan is complete, the images are analyzed by a radiologist or another trained physician. The results are reported using standardized metrics, primarily the T-score and the Z-score, which compare the patient’s bone density to established norms. The T-score compares the patient’s BMD to that of a healthy young adult, while the Z-score compares it to people of the same age, size, and gender. The radiologist sends a detailed report to the ordering or primary care physician, who then discusses the results and any necessary treatment plan with the patient.