I am sad to inform you that you have no future as a supervillain.
With a radiation source like this even a dust sized particle, if ingested or inhaled, is enough to cause excruciating death. Anything that turns the capsule into a powder and releases it into the air near a large group of people or into a water source or even a public pool could cause mass fatalities.
Mass fatalities, no. Source: I have worked in Chernobyl.
But anyway that's a way better suggestion because you can split one source into a vast multitude of opportunities to slit into someone's pillow. So excruciating death it is.
With a radiation source like this even a dust sized particle, if ingested or inhaled, is enough to cause excruciating death. Anything that turns the capsule into a powder and releases it into the air near a large group of people or into a water source or even a public pool could cause mass fatalities.