Compensators are used to address what kind of patient features?

Compensators are utilized primarily to account for sloping skin surfaces and variations in patient thickness across the target volume. This is especially important in radiation therapy where uniform dose distribution is crucial for effective treatment while minimizing exposure to surrounding healthy tissues.

When a patient's anatomy doesn't have a consistent contour—due to factors like varying thickness of tissues or irregularities in body shape—compensators help to modulate the radiation beam. They can either attenuate or enhance the radiation dose delivered based on the specific geometrical variations. By using compensators, dosimetrists can ensure that the prescribed dose reaches the tumor while protecting the adjacent healthy tissues from excessive radiation.

Other options refer to different considerations in patient treatment. Variance in patient age can affect the choice of treatment, but it is not something that compensators specifically address. Changes in patient positioning and movement during treatment are critical factors that need to be managed, but they fall under different clinical practices and techniques such as immobilization devices or motion management strategies rather than the application of compensators. Therefore, the emphasis on sloping skin surfaces and varying patient thickness accurately reflects the primary function of compensators in medical dosimetry.