A method for measuring the regional bone mineral density (rBMD) in human lumbar vertebral bodies using a series of contiguous computed tomography images, each 1 mm thick, is fully described. The technique has a sample volume of 0.004 cm3, a sample spacing of 0.8 X 0.8 X 1.0 mm, and results in a bone marrow radiation dose of 1.59 to 2.75 rads (0.016-0.028 Gy). The use of physical density (mg/cm3) is introduced and the measurement noise (0.7-1.3%), accuracy (2.7%), and serial precision (0.2%) have been evaluated in vitro using appropriate phantoms. The corresponding percentage errors for accuracy and precision relative to K2HPO4 concentration were 6.9% and 2.0%, respectively. A multiple region density measurement is described and evaluated.