The standard procedure in bone mineral measurements of the lumbar spine with QCT is presented in detail and analyzed with respect to the steps that may influence the accuracy and precision of the measurement. As new technical and methodological approaches, we present an improved implementation of dual energy CT and algorithms for automated determination of the CT slice and the evaluation region of interest. Dual energy methods provide greater accuracy; the automated algorithms relieve the operator of a tedious task and ensure greater precision. With respect to the clinical requirement to determine changes in bone mineral density as reliably and as early as possible, the precision increasing measures are considered more important. They also constitute a new methodological concept in radiology. Dual energy CT is only recommended for basic studies at this time.