Cesium is a trace mineral. I have no idea if it helps TS. It would be difficult to find it as a separate supplement; there are only a couple of places online I think. A trace mineral complex would have it.
I've read that it is used for cancer. I don't know if it has many other uses than that. I can't remember the name of one company that makes it. Its something pharmacologica or something pharma___. Sounded like a foreign name.
Its expensive though. It would cost at least $60 for a bottle.