Radiation therapy for testicular cancer is external, meaning the radiation is administered by a focused beam from a machine outside the body. The main drawback of this method is that the radiation can also destroy nearby healthy tissue.

A radiation oncologist will determine the exact amount of radiation required to treat the cancer, including the dose and the number of treatments.

External beam radiation therapy is administered in a radiation oncology center by specially trained radiation oncologists, usually on an outpatient basis. Prior to treatment, a therapist will mark the part of the body that is to be treated with a special pen. The radiation is delivered using a device that resembles a normal x-ray machine. The treatment itself is generally painless.

Radiation therapy is particularly effective for treating seminomas.