What term describes an x-ray beam with multiple energy levels?

The term that describes an x-ray beam with multiple energy levels is polyenergetic. In radiography, polyenergetic beams consist of a range of photon energies rather than a single energy value. This characteristic is important because the variety of energies can produce different interactions with matter, affecting image contrast and tissue penetration.

In medical imaging, polyenergetic x-ray beams are more common, as they are generated from various sources, such as x-ray tubes, where the high-speed electrons produce a spectrum of x-ray energies. The different energy levels contribute to the overall effectiveness of the imaging process by allowing certain tissues to be visualized better, enhancing diagnostic quality.

On the other hand, the terms anisotropic and isotropic refer to the directional properties of radiation rather than energy levels. Monoenergetic, on the other hand, describes a beam that contains only one specific energy level, which is not applicable for typical x-ray beams used in clinical practice.