TABLE 1.

Data on Performance of Generators Based on 220Rn Emanation from Source of 224Ra or 228Th in Equilibrium with Its Daughters

Type of generatorYieldAvailable 212Pb in washoutRadioactivity breakthrough of parent source nuclide
224Ra source62% (56%*)91%0.02%† (0.0004%–0.14%)
228Th source 68%‡87%0.0001%–0.005%

  • ↵* Second-time use of generator (n = 3).

  • ↵† Average of 9.

  • ↵‡ Average of multiple uses of single generator (n = 8).

  • ↵ In 6/8 samples, measured radioactivity was below quantification limit after >2 mo (<0.0015% breakthrough; Supplemental Section 1).