When using bolus, what is the primary effect on the skin dose during radiation treatment?

The primary effect of using bolus in radiation therapy is that it elevates the skin dose. Bolus material is placed on the surface of the skin to bring the radiation dose closer to the surface. This is particularly important in treatments where the target is located near the skin surface, such as in certain types of skin cancers.

When bolus is used, it effectively compensates for any irregularities in the patient's anatomy and allows for a more uniform distribution of the radiation dose, which is especially beneficial for superficial tumors. It decreases the tissue-air ratio, resulting in an increased dose delivered to the skin compared to what would be delivered without bolus. Additionally, the bolus ensures that the highest dose is delivered at the desired depth while protecting deeper tissues from excessive radiation exposure.

Therefore, using bolus not only raises the skin dose but also plays a crucial role in optimizing treatment effectiveness while minimizing damage to underlying healthy tissues.