Does radiotherapy make me radioactive?

External radiotherapy, where radiation is produced by a machine outside the body and then aimed at the tumor, does not make you radioactive.

Brachytherapy or internal radiotherapy is a type of radiotherapy in which radioactive material sealed in needles, seeds, wires, or catheters is placed directly into or near a tumor. They give an intense radiation dose to the tumor and its immediate surroundings. While radioactive material in your body is still active, you are indeed slightly radioactive. Some restrictions might be imposed on who visits you when you get this therapy as an inpatient treatment. If you receive brachytherapy as an outpatient treatment, you will have the radioactive material in your body for a longer time. Because, the dose of radiation is lower it cannot reach the surface of the body. All this can be carefully explained by the staff treating you.

If you receive radioisotopes in pills or by shots as a form of radiotherapy, some radioactive sources are going to be excreted through body fluids like urine, sweat or saliva. This kind of radiotherapy is usually administered in an inpatient setting but it can be done in an outpatient setting as well. In the latter case, you will receive counseling from the staff in charge of your treatment.