Physical Half-Lives and Qualitative Comparison of Common Radioiodine Isotopes for Imaging in Theranostics
| Property | 124I | 131I |
| Physical half-life (h) | 100.22 | 192.50 |
| Radiation | β+, ε | β−, γ |
| Availability | Limited | Common |
| Cost | Expensive | Low |
| Imaging system | PET/CT | SPECT/CT |
| System sensitivity (cps/Bq) | High | Low |
| Quantification (attenuation, scatter) | Good | Limited |
| Image quality | High | Low |
| Clinical spatial resolution (mm) | 6–8 | 14–17 |
| Late imaging (≥96 h) | Yes | Yes |
| “Stunning effect” | ? (No) | High |