Table 1.
Radiometals for therapy with their half-life (t1/2), decay characteristics, path length in tissue and reported chelators
| Radiometal | t1/2 | Decay Properties (MeV) | Path Length | Reported Chelator(s) |
|---|---|---|---|---|
| α-emitters | ||||
| 223Ra | 11.4 d | 5.8-7.53 (α) 17ˆ | 46-68 μm 17 | H2macropa 18 |
| 225Ac | 9.9 d | 5.8-8.4 (α) 19ˆˆ | 47-85 μm† 19 | DOTA, H2macropa, Crown 20-26 |
| 227Th | 18.7 d | 6.14 (α) 27 | ‡ | DOTA, Me-3,2-HOPO 28-30 |
| 212Pb* | 10.6 h | 6.05 (α)** 27 | DOTA, TCMC 31,32 | |
| 212Bi | 60.6 min | 6.05 (α, 36%) 27; 0.834 (β-, 64%) 27 | 51-92 μm 3 | 3p-C-DEPA, NETA, DOTA, CHX-A”-DTPA 29,30,33 |
| 213Bi | 45.6 min | 5.87 (α, 2.2%) 19,27; 0.492 (β-, 97.8%) 27 | 48-85 μm 3 | 3p-C-DEPA, NETA, DOTA, CHX-A”-DTPA 29,30,33 |
| β--emitters | ||||
| 177Lu | 6.7 d | 0.497 (β-) 3 | 1.8 mm 3 | DOTA, NETA, CHX-A”-DTPA 30,34-37 |
| 90Y | 2.7 d | 2.28 (β-) 3 | 11.3 mm 3 | DOTA, NETA, CHX-A”-DTPA, DTPA 30,34,38-40 |
| 67Cu | 2.6 d | 0.395 (β-) 41 | 2.1 mm 3 | DOTA, NOTA 42,43 |
| 188Re | 17 h | 2.12 (β-) 3,44 | 10.4 mm 3 | Direct, MAG2-GABA, Trisuccin 45 |
| 64Cu | 12.7 h | 0.573 (β-, 38.4%) 41 | 0.95-1.4 mm 46 | TETA, DOTA, NOTA; p-SCN-Bn-Oxo-DO3A, p-SCN-Bn-Oxo-PCTA 47 |
| Auger Electrons | AE Energy Released/Decay (keV) | |||
| 67Ga | 3.26 d | 6.3 (AE) 48,49 | 0.002-2.1 μm 50 | DFO, NOTA, DOTA, PCTA, p-NH2-Bn-Oxo-DO3A 30 |
| 111In | 2.8 d | 6.8 (AE) 48,49 | 2-500 nm 51 | DOTA, CHX-A”-DTPA, H4octapa, NOTA, DTPA 52 |
| 64Cu | 12.7 h | 2 (AE, 41%) 53 | 126 nm 53 | TETA, DOTA, NOTA; p-SCN-Bn-Oxo-DO3A, p-SCN-Bn-Oxo-PCTA 47 |
ˆ 223Ra yields four high-energy α-particles per disintegration.
ˆˆ 225Ac yields four α-particles per disintegration with energies ranging from 5.8 to 8.4 MeV. Three α-particles are emitted to decay to 213Bi, then one alpha particle is emitted from the two routes of decay to 209Bi.
†The range of α-emissions is defined by the α-emitting daughter isotopes of 225Ac.
‡227Th does not have a defined range of α-emissions due to successive α-emitting daughter isotopes.29
*212Pb is a β- emitter but produces the daughter isotope 212Bi and is often used for targeted α therapy due to the short half-life of 212Bi.
** α energy emitted by 212Bi.
Abbreviations: DOTA, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid; H2macropa, N,N'-bis[(6-carboxy-2-pyridil)methyl]-4,13-diaza-18-crown-6; Crown, 2,2',2'',2'''-(1,10-dioxa-4,7,13,16-tetraazacyclooctadecane-4,7,13,16-tetrayl)tetraacetic acid;Me-3,2-HOPO, 3-hydroxy-N-methyl-2-pyridinone; TCMC, 1,4,7,10-tetraza-1,4,7,10-tetra(2-carbamoylmethyl)cyclododecane; 3p-C-DEPA, 2-[(carboxymethyl)][5-(4-nitrophenyl-1-[4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl]pentan-2-yl)amino]acetic acid; NETA, ({4-[2-(Bis-carboxymethyl-amino_ethyl]-7-carboxymethyl-[1,4,7]triazonan-1-yl}; DTPA, diethylenetriamine pentaacetic acid; CHX-A”-DTPA, cyclohexane-1,2-diamine-pentaacetic acid; TETA, 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid; NOTA, 1,4,7-triazacyclononane-1,4,7-triacetic acid; MAG2-GABA, S-ethoxyethyl mercapto-acetylglycylglycyl aminobutyrate; Trisuccin, N-[tris[2-[(N-hydroxyamino)carbonyl]ethyl]methyl]succinamic acid; p-SCN-Bn-Oxo-DO3A, 1-Oxa-4,7,10-triazacyclododecane-5-S-(4-isothiocyanatobenzyl)-4,7,10-triacetic acid; p-SCN-Bn-Oxo-PCTA, 3,6,9,15-tetraazabicyclo[9.3.1] pentadeca-1(15),11,13-triene-4-S-(4-isothiocyanatobenzyl)-3,6,9-triacetic acid; HBED, N,N'-bis (2-hydroxybenzyl) ethylenediamine-N,N'-diacetic acid; DFO, desferrioxamine; H4octapa, N,N'-bi(6-carboxy-2-pyridylmethyl)ethylenediamine-N,N'-diacetic acid).