Radionuclides used in positron emission tomography (PET) typically possess short physical half-lives, T_1/2 (e.g., T_1/2 of ¹⁵O = 2.03 min, ⁶²Cu = 9.67 min, ¹³N = 9.96 min, ¹¹C = 20.4 min, ⁶⁸Ga = 67.7 min, ¹⁸F = 109.8 min, ⁶⁴Cu = 12.7 h). As a result, these radionuclides usually are produced using particle acceleration techniques (e.g., cyclotrons) or from generators, and then are processed into the final PET drug product in close proximity to the site where the PET procedure will be conducted.