And also a nice discussion about how US cities that are most likely to be targets are probably to secure to be easy targets. This story should illustrate it.
"Take, for example, an incident involving a Washington lawyer of a certain age who went to his doctor a few months ago for a routine heart checkup. (No, no, despite his profession, a heart was indeed located.)
The exam included a stress test with injection of a radioactive isotope -- most likely technetium or thallium -- which helps illuminate the heart muscle during exercise. The doctor told him he passed.
The elated lawyer says he left work several hours later and was driving along I Street NW between 16th and 17th when a police car with lights flashing zipped up behind him. An officer on a bicycle pulled alongside.
What could this be? Couldn't be speeding, a red light or a stop sign.
"Sir," the officer explained, "you were not pulled over because of a traffic violation. You were pulled over because you are radioactive."