Sentence:  For most patients, the old-fashioned basal metabolism test is a mild form of torture . . . and four Navy researchers have come to the conclusion that in big medical centers with facilities for handling radioisotopes it should be replaced by the "<WSD>atomic cocktail</WSD>." 
Meaning of the word marked with <WSD> tags:  A drinkable liquid containing a radioactive substance, used in health care either as a diagnostic aid or as a treatment, especially for cancer of the thyroid.