Radiation therapist Jean Etienne holds a range compensator, which shapes the depth to which the proton beam enters a patient's body to target a tumor. Rebecca Davis/NPR hide caption

itoggle caption Rebecca Davis/NPR

This illustration shows a device made by MammoSite used to deliver targeted doses of radiation as part of brachytherapy. Courtesy Radiological Society of North America hide caption

itoggle caption Courtesy Radiological Society of North America