What is the correct placement distance for a missing tissue compensator from the skin?

The correct placement distance for a missing tissue compensator from the skin is at least 15 cm. This distance is important because the compensator is used to ensure that the dose distribution of radiation therapy remains uniform, particularly when treating areas where there is a change in tissue density, such as in the presence of a tumor or after surgical resection.

When the compensator is properly placed at least 15 cm from the skin surface, it allows for adequate buildup of radiation energy to achieve the desired dose to the target tissues while minimizing the radiation exposure to the surrounding healthy tissues. This optimal distance helps to account for scatter and provides a more accurate representation of the treatment plan, enhancing the effectiveness of the radiation therapy.

Greater distances, such as those mentioned in other options, could result in insufficient buildup of radiation, potentially leading to underdosage of the target area or increased exposure to surrounding normal tissues. Thus, maintaining this distance is crucial for achieving a balanced and effective treatment outcome.