When using a divergent block, what is the main purpose?

The primary purpose of using a divergent block is to minimize transmission penumbra. When delivering radiation therapy, achieving precise targeting is crucial to ensure that the maximum dose is delivered to the tumor while minimizing exposure to surrounding healthy tissues. Transmission penumbra refers to the region around the edge of the radiation beam where the dose rapidly changes, which can lead to dose uncertainties at the treatment boundary.

A divergent block is designed to shape the radiation beam by blocking certain angles or paths that the radiation would otherwise travel. By doing so, it effectively reduces the transmission penumbra, ensuring that the dose falls off more sharply at the edges of the treatment area. This allows for a clearer distinction between the treated area and the adjacent healthy tissue, leading to more effective treatment while safeguarding against potential damage to surrounding organs.

Using a divergent block does not inherently enhance the skin dose, reduce scatter significantly, or increase penumbra width. Instead, the emphasis is on the proper delineation of the treatment area to achieve optimal dosimetric outcomes.