Total dose incurred by patients and staff from BMD measurement using a new 2D digital bone densitometer

Dual energy X-ray absorptiometry (DXA) is a widely used and precise technique for non-invasive assessment of bone mineral density. The DXA systems have evolved from pencil X-ray beam (single detector) to fan beam (linear array detector) and recently cone beam densitometers (bi-dimensional detector), allowing for an examination to occur without any scanning and with a short acquisition time. The purpose of this study was to evaluate patient and staff dose from a new cone beam densitometer, the DMS Lexxos. Measurements were performed on a DMS Lexxos bone densitometer prototype. An anthropomorphic phantom and thermoluminescent dosimeters were used to evaluate the effective dose. Ionization chambers and electronic personal dosimeters were used to evaluate the staff dose. The effective dose is 8.4 µSv for an anteroposterior spine examination and 4.8 µSv for a femoral neck in standard mode. The averaged scattered dose rate (ambient dose equivalent) at 1 m from the beam is evaluated at 226 µSv/h. Assuming six patients per hour with two views per patient, the time averaged dose rate is evaluated at 2.9 µSv/h. By the personal dosimeter, the staff dose (Hp 10) at 1 m from the beam is evaluated at 0.23 µSv per examination. For one examination, patient and staff dose from this new technology remains low: in the same range as the fan-beam densitometer.