Which of the following is a characteristic of a flattening filter?

A flattening filter is an essential component used in radiation therapy to modify the beam profile of a linear accelerator. Its primary function is to create a more uniform dose distribution across the treatment area.

The characteristic that best describes a flattening filter is that it hardens the beam more in the central region compared to the peripheral regions. This means that, as the beam passes through the filter, higher energy photons are preferentially allowed to pass through from the central region, while lower energy photons are attenuated more in that region compared to the edges. The result is a flatter, more uniform beam profile at the isocenter, which helps ensure that the desired dose is delivered effectively to the tumor while minimizing exposure to surrounding healthy tissue.

The other options either misrepresent the function of the flattening filter or provide incorrect information. The flattening filter does not drastically reduce exposure time; its primary function is related to beam profile rather than exposure duration. It also does not eliminate scatter radiation, as scatter can still occur because of tissue interactions within the patient. Finally, while the flattening filter aims to create a uniform intensity distribution across the treatment field, it does so by modifying the beam profile rather than simply increasing intensity equally across the field.