What is the Origin of Dual X-Ray Absorptiometry?

The technique was developed in the late 1980s, representing a technological evolution from earlier single-photon and dual-photon absorptiometry methods. The name precisely describes the method, utilizing two distinct energy beams of X-rays. Its origin is a fusion of medical physics and diagnostic radiology, driven by the need for a precise, reproducible method to quantify bone loss. DXA rapidly became a central tool in endocrinology and geriatric medicine for skeletal assessment.

What is the Mechanism of Dual X-Ray Absorptiometry?

The DXA scanner directs two X-ray beams, each with a different energy level, through the region of interest, typically the lumbar spine or proximal femur. Bone and soft tissues differentially absorb these two beams based on their density. Sophisticated computer algorithms then analyze the ratio of photon absorption for each beam, allowing for the precise subtraction of soft tissue effects from the total signal. This calculation yields a highly accurate measurement of BMD in grams per square centimeter, which is then used to generate clinically relevant T-scores and Z-scores.

Dual X-Ray Absorptiometry

Meaning

Dual X-Ray Absorptiometry, widely known by its acronym DXA or DEXA, is a specialized, low-dose radiographic technology used in clinical practice to accurately measure bone mineral density (BMD) and quantify body composition. This non-invasive diagnostic procedure is considered the gold standard for assessing skeletal health, diagnosing osteoporosis, and monitoring therapeutic responses to bone-sparing medications. The resulting quantitative data is crucial for physicians in accurately calculating a patient’s absolute risk of fracture.