ABSTRACT

Projection imaging refers to the acquisition of a twodimensional image of the patient’s three-dimensional anatomy. Projection imaging delivers a great deal of information compression, because anatomy that spans the entire thickness of the patient is presented in one image. A single chest radiograph can reveal important diagnostic information concerning the lungs, the spine, the ribs, and the heart, because the radiographic shadows of these structures are superimposed on the image. Of course, a disadvantage is that, by using just one radiograph, the position along the trajectory of the X-ray beam of a specific radiographic shadow, such as that of a pulmonary nodule, is not known.