Does radiation therapy make me radioactive?

Yes/no: Most commonly used radiation is external beam radiation. This is a high energy x-ray or protons typically and this does not make you radioactive. Sometimes we plant radioactive seeds inside the patient or inject radioactive substance or pills are taken orally. This form of radiation can make one radioactive for a short period of time.

Generally Not: Assuming you mean external beam radiation therapy, there is no safety concerns for radioactivity.

Generally NO: Most people are treated with external radiation. This leaves no residual radiation in the body, it's like having an x-ray. Once the machine is off, there is no more radiation. Some people are treated with permanent radioactive implants. These then stay in the body and give off radiation for a while. You wouldn't be radioactive, but radiation could be detected coming from you for a while.