From: Precise activity measurements of medical radionuclides using an ionization chamber: a case study with Terbium-161
Radionuclides
Energy of gamma lines (keV)
Response difference (%)
161Tb
49–75
8.5
137Cs
662
0.23
60Co
1173–1332
0.21
133Ba
276–384
0.42
57Co
122–136
0.6