Which of the following describes a typical use of bolus material in radiation therapy?

Bolus material plays a crucial role in radiation therapy, primarily by adapting the dose distribution of the radiation beam. When used in treatment, bolus is applied to the skin surface or over the area being treated to bring the dose closer to the surface. This is particularly important in cases where the target tumor is located just underneath the skin, as it enhances the dose delivered to that specific area while reducing the dose to underlying tissues.

By modifying the path of the radiation beam, bolus ensures that the prescribed dose is delivered effectively to the treatment area, which is essential for maximizing treatment efficacy while minimizing side effects to surrounding healthy tissue. The material used for bolus can be made of various substances that help achieve this objective by providing a certain thickness that can be adjusted based on individual patient needs.

Other options, while related to patient care in radiation therapy, do not capture the primary intended function of bolus material. For example, improving imaging contrast pertains to techniques in imaging rather than treatment delivery, supporting the patient relates to comfort and positioning rather than treatment accuracy, and creating a tighter fit for the treatment area may refer more to the patient positioning and immobilization devices rather than the specific application of bolus in modifying radiation dose distribution.