Interest in bone densitometry methods has recently experienced a resurgence within the medical community. Physicians have become more interested than ever before in the diagnosis and treatment of degenerative diseases of bone such as osteoporosis. The public perception of osteoporosis and its prevention has been recently heightened. Because osteoporosis is widespread, especially in women, and leads to an increase in fractures in our population, many re- searchers and clinicians are strongly motivated in their search for more sensi- tive and accurate methods of diagnosis. This book was written for physicians, scientists, engineers, medical phy- sicists, and others desiring an introduction or further understanding of this exciting field. Beginning with the early development of x-ray film methods for assessing bone status, the field has steadily grown throughout the years. Novel and interesting devices have been designed for the measurement of bone mass, bone density, cortical thickness, and other parameters of bone changes. Both qualitative and quantitative bone methods are described. The techniques include imaging devices such as CT and radiography as well as fixed point methods in which bone characteristics of a region of interest are analyzed.