The 40K activity of one gram of potassium.
Watson
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D002138:Calibration; D006801:Humans; D019047:Phantoms, Imaging; D011188:Potassium / Q000032:analysis* / Q000737:chemistry; D011197:Potassium Radioisotopes / Q000032:analysis*
D011197:Potassium Radioisotopes; D011188:Potassium