A hybrid calibration method uses a calibration phantom (exterior
reference) scanned simultaneously with the patient, and one or more known
tissues of the subject (interior reference) to create a hybrid
calibration reference that improves the measurement of tissue densities
throughout the body. In addition, the calibration method is used to
quantitatively define boundaries of tissue and organs for more accurate
measurements of lengths, areas and volumes. Another aspect of the
invention uses the calibrated images to quantitatively preset absolute
window/levels for filming and image display, which provides standardized
viewing for diagnostic purposes.