What is the purpose of a flattening filter in radiation therapy?

The purpose of a flattening filter in radiation therapy is primarily to enhance dose uniformity across the treatment field. When radiation beams are generated, they often exhibit a non-uniform intensity distribution, with the highest intensity occurring at the center of the beam. The flattening filter is designed to modify this profile by attenuating the central part of the beam more than the peripheral areas, which allows for a more even distribution of dose across the target area.

Specifically, by using a flattening filter, the intensity of the central region of the beam is reduced, resulting in a flatter dose profile that conforms better to the shape and size of the tumor being treated. This enhanced uniformity is critical in ensuring that cancerous tissues receive an adequate dose while minimizing radiation exposure to surrounding healthy tissues.

In contrast, the other options focus on aspects that are not the primary function of a flattening filter. While it does interact with the energy spectrum, modifying it specifically to enhance uniformity is its more prominent role in clinical settings.