b. Straight Central Ray. A straight central ray forms a 90 degree angle with the film. A
straight CR may be vertical perpendicular (VP) or horizontal perpendicular (HP).
straight central ray: forms a 90 degree angle with the film.
Figure 3-49. This straight CR is vertical perpendicular.
c. Angled Central Ray. Alternatively, the central ray may be angled rather than straight.
If the central ray is angled, then it forms an angle of less than 90 degrees with the film.
angled central ray: central ray that forms an angle of less than 90 degrees with the
(1) Angled CR, cephalic. If the angled CR is cephalic, it means that the CR
is angled up toward the head, as in figure 3-50 below.
Figure 3-50. Angled CR, cephalic.