A doctor places a core into the helmet of a Gamma Knife device used for radiation therapy. Gamma Knife devices use Cobalt-60 as a radiation source.
Image Credit: University of South Carolina Gamma Knife Center
For decades, Cobalt-60 has been used for radiation treatments used against various cancers. In the image above, you can see a doctor fitting a helmet used in a device that uses Cobalt-60 as a radiation source.
Such devices ionize cancerous tissue with concentrated beams of radiation, leading to the death of cancer cells. Outside of the careful oversight of physicists and doctors, however, Cobalt-60 can be incredibly dangerous. For example, experts expect the two thieves in the recent case to suffer from radiation sickness or possibly die due to their exposure.