Carolyn Vachani, RN, MSN OncoLink Nurse Educator at Penn Medicine, responds:
With all kids, you have to bring it to their level, but also ask questions - ask them what they understand, what they want to know and don't over think your answers. Often your first instinct to answer is what they want and let them ask follow up questions. They often understand a lot more than we think and if you are not open with them, their imagination can come up with far worse things than reality.
Here are some resources to help you understand the process and explain it to your child:
We have an article that discusses the steps of radiation that can be helpful. CHOP has a great video for kids about proton therapy, though the procedure is very similar to traditional radiation, so it could be used to explain either modality. A great video for kids from a UK based hospital charity is called One of a Kind.