Radiation therapy
Radiation therapy can also be used in non-malignant conditions, such as the treatment of trigeminal neuralgia, severe thyroid eye disease, pterygium, pigmented villonodular synovitis, and prevention of keloid scar growth, vascular restenosis, and heterotopic ossification.  Doctors limit the use of radiation therapy in non-malignant conditions because they worry about the radiation could start new cancers.