Patient doses in bone mineral densitometry.

Procedures were developed to compute effective dose equivalent (H(E)) values for patients undergoing bone mineral densitometry (BMD) measurements such as dual energy X-ray absorptiometry (DEXA) and quantitative computed tomography (QCT). Representative values of H(E) were determined for patients undergoing each type of BMD procedure. Typical DEXA measurements are associated with an H(E) of about 2.5 microSv. For QCT, the values of H(E) are 300 microSv for single energy techniques and 1 mSv for dual energy techniques, respectively. By comparison, a single well collimated abdominal X-ray examination often taken in conjunction with DEXA studies results in an H(E) of about 100 microSv. BMD patient doses are at the lower end of the exposure range encountered in diagnostic radiology. As a result, radiation dose is not a primary factor in choosing the method for BMD determination.