Low-dose CT scanning for quantitative spinal mineral analysis.

The effect of x-ray exposure on the precision of quantitative CT bone mineral measurements was determined using excised vertebrae and phantoms. Specimens were scanned at 80 kVp with exposures ranging from 23 to 380 mAs using the UCSF/GE research scanner, a modified GE CT/T 7800. Dose was measured using thermoluminescent dosimeters. A patient exposure of 100 mrem (10(-3) Sv) was judged adequate to provide useful quantitative vertebral mineral measurements with this scanner.