an implement consisting of a broad blade or scoop attached to a long handle, used for taking up, removing, or throwing loose matter, as earth, snow, or coal. 2. any fairly large contrivance or machine with a broad blade or scoop for taking up or removing loose matter: a steam shovel. 3. a shovelful.
Cone beam computed tomography. Cone beam computed tomography. MeSH. Cone beam computed tomography (or CBCT, also referred to as C-arm CT, cone beam volume CT, or flat panel CT) is a medical imaging technique consisting of X-ray computed tomography where the X-rays are divergent, forming a cone.
CONVEX or POSITIVE lenses will CONVERGE or FOCUS light and can form an IMAGE. CONCAVE or NEGATIVE lenses will DIVERGE (spread out) light rays. You can have mixed lens shapes too: See a demonstration (opens a new window) of what happens to the light path when you combine several convex or concave lenses. Perfectly straight, until something bends it. The straight paths of light are called LIGHT RAYS.