A. Mark Davies, Holger Pettersson. The who manual of diagnostic imaging. Malta, World Health Organization, 2002.

Modern diagnostic imaging offers a vast spectrum of modalities and techniques, which enables us to study the function and morphology of the human body in details that approaches science fiction. However, it should be noticed that even in the most advanced Imaging Department in the economically privileged parts of the world, 70-80% of all clinically relevant questions may be solved by using the two main cornerstones of diagnostic imaging, which are Radiography (X-ray) and Ultrasonography. It should also be remembered that thousands of hospitals and institutions worldwide do not have the possibilities to perform even these fundamental imaging procedures, for lack of equipment and/or diagnostic imaging skills.