What effect does the use of bolus in treatment planning typically have?

The use of bolus in treatment planning is primarily designed to bring the homogenous dose distribution closer to the surface of the patient's skin. When bolus material is placed on the skin, it effectively eliminates the skin-sparing effect that occurs with high-energy photon beams. This is crucial in scenarios where the clinician aims to ensure that the prescribed dose reaches the target volume, particularly in cases where the tumor is located near the surface of the skin.

By removing the skin-sparing effect, the bolus increases the dose that the skin receives, thus facilitating the delivery of a therapeutic dose to the tumor while ensuring adequate exposure to the superficial layers of tissue. This is especially important in the treatment of skin cancers or in areas where dose escalation is necessary.

Other options may suggest benefits or effects of bolus that are not aligned with its primary physiological impact in treatment planning. Thus, the primary understanding is that bolus increases the skin dose by minimizing the inherent sparing effect that high-energy beams would otherwise provide.