Hi @RachelG the bolus is used to act as an extra layer of skin to trick the radiation (I won’t bore you with the physics) This means that your actual skin surface will receive a higher dose. It is usually used for chest wall treatments where the skin was involved or the margins weren’t clear. It can also be used to bring dose out of the lung if there is not enough tissue.
If your Centre offers the mepitel film I would ask if you can have it as it may help lessen your skin reaction, otherwise just ensure you moisturise at least 3 times per day with a recommended cream. The therapists and nurses will keep an eye on your skin (as they do for any patient) sometimes the bolus is alternate days or for the first half of treatment or will be taken off if your skin reaction does get quite bad.
Hope that helps, any more questions feel free to ask xx