With helical MDCT, a volume of tissue is imaged to capture a texture of the trabecular bone at skeletal sites such as the spine and the hip. The advantage is that a full data set is obtained, providing important information about bone structure. However, HR CT is associated with a considerably higher radiation dose compared with the X-ray examinations commonly used in routine clinical practice for the estimation of bone status. Indeed, compared with the 0.06 to 0.3 mSv patient effective dose associated with QCT applied to 2D slices in the lumbar spine, studies show that protocols used to examine vertebral microstructure using HR MDCT provide an effective dose of about 3 mSv [45, 46]. This dose is similar to that delivered to the patient from 3D QCT of the hip (Table 3).