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

The primary purpose of a flattening filter in radiation therapy is to ensure uniform dose distribution across the treatment field. When high-energy radiation beams are generated, they often have a non-uniform intensity distribution, with the center of the beam being much stronger than the edges. The flattening filter is designed to reshape this intensity profile, thereby ensuring that the dose delivered to the tumor is consistent and uniformly distributed across the entirety of the target area. This uniformity is critical for achieving effective treatment while minimizing the risk of underdosing some areas and overdosing others, which could lead to suboptimal outcomes or increased toxicity.

The other options do not correctly represent the main function of the flattening filter. While absorption and intensity modifications are important aspects of radiation therapy, they are not the primary purposes of the flattening filter itself. Additionally, minimizing side effects is an overall goal of radiation therapy but is achieved through various means beyond just the action of a flattening filter.