Thallium is a chemical element with the symbol Tl and atomic number 81. It is a soft, silver-gray metal that can be toxic to living organisms. Full definition
In the front yard of his house were tire tracks and leftover evidence of meat poisoned with thallium. (si.com)
If you're stable for 6 years with no other cardiovascular impairments and a normal current thallium stress test, then you can obtain «Standard» rates without a rating. (rootfin.com)
The Canadian study showed a jump in the false positive rate when thallium scans were substituted for Tc - 99m scans during the shortage. (sciencedaily.com)