# Isotopes of gallium

Natural gallium ($_{31}$Ga) consists of a mixture of two stable isotopes: gallium-69 and gallium-71. Twenty-nine radioisotopes are known, all synthetic, with atomic masses ranging from 60 to 89; along with three nuclear isomers, $^{64m}$Ga, $^{72m}$Ga and $^{74m}$Ga. Most of the isotopes with atomic mass numbers below 69 decay to isotopes of zinc, while most of the isotopes with masses above 71 decay to isotopes of germanium. Among them, the most commercially important radioisotopes are gallium-67 and gallium-68.
Gallium-67 (half-life 3.3 days) is a gamma-emitting isotope (the gamma ray emitted immediately after electron capture) used in standard nuclear medical imaging, in procedures usually referred to as gallium scans. It is usually used as the free ion, Ga$^{3+}$. It is the longest-lived radioisotope of gallium.
The shorter-lived gallium-68 (half-life 68 minutes) is a positron-emitting isotope generated in very small quantities from germanium-68 in gallium-68 generators or in much greater quantities by proton bombardment of $^{68}$Zn in low-energy medical cyclotrons, for use in a small minority of diagnostic PET scans. For this use, it is usually attached as a tracer to a carrier molecule (for example the somatostatin analogue DOTATOC), which gives the resulting radiopharmaceutical a different tissue-uptake specificity from the ionic $^{67}$Ga radioisotope normally used in standard gallium scans.

## List of isotopes

| Nuclide | Z | N | Isotopic mass (Da) | Half-life | Decay mode | Daughter isotope | Spin and parity | Natural abundance (mole fraction) | Natural abundance (mole fraction) |
| Nuclide | Excitation energy | Excitation energy | Excitation energy | Half-life | Decay mode | Daughter isotope | Spin and parity | Normal proportion | Range of variation |
| $^{60}$Ga | 31 | 29 | 59.95750(22)# | 72.4(17) ms | β$^+$ (98.4%) | $^{60}$Zn | (2+) | | |
| $^{60}$Ga | 31 | 29 | 59.95750(22)# | 72.4(17) ms | β$^+$, p (1.6%) | $^{59}$Cu | (2+) | | |
| $^{60}$Ga | 31 | 29 | 59.95750(22)# | 72.4(17) ms | β$^+$, α? (<0.023%) | $^{56}$Ni | (2+) | | |
| $^{61}$Ga | 31 | 30 | 60.949399(41) | 165.9(25) ms | β$^+$ | $^{61}$Zn | 3/2− | | |
| $^{61}$Ga | 31 | 30 | 60.949399(41) | 165.9(25) ms | β$^+$, p? (<0.25%) | $^{60}$Cu | 3/2− | | |
| $^{62}$Ga | 31 | 31 | 61.94418964(68) | 116.122(21) ms | β$^+$ | $^{62}$Zn | 0+ | | |
| $^{63}$Ga | 31 | 32 | 62.9392942(14) | 32.4(5) s | β$^+$ | $^{63}$Zn | 3/2− | | |
| $^{64}$Ga | 31 | 33 | 63.9368404(15) | 2.627(12) min | β$^+$ | $^{64}$Zn | 0(+#) | | |
| $^{64m}$Ga | 42.85(8) keV | 42.85(8) keV | 42.85(8) keV | 21.9(7) μs | IT | $^{64}$Ga | (2+) | | |
| $^{65}$Ga | 31 | 34 | 64.93273442(85) | 15.133(28) min | β$^+$ | $^{65}$Zn | 3/2− | | |
| $^{66}$Ga | 31 | 35 | 65.9315898(12) | 9.304(8) h | β$^+$ | $^{66}$Zn | 0+ | | |
| $^{67}$Ga | 31 | 36 | 66.9282023(13) | 3.2617(4) d | EC | $^{67}$Zn | 3/2− | | |
| $^{68}$Ga | 31 | 37 | 67.9279802(15) | 67.842(16) min | β$^+$ | $^{68}$Zn | 1+ | | |
| $^{69}$Ga | 31 | 38 | 68.9255735(13) | Stable | Stable | Stable | 3/2− | 0.60108(50) | |
| $^{70}$Ga | 31 | 39 | 69.9260219(13) | 21.14(5) min | β$^−$ (99.59%) | $^{70}$Ge | 1+ | | |
| $^{70}$Ga | 31 | 39 | 69.9260219(13) | 21.14(5) min | EC (0.41%) | $^{70}$Zn | 1+ | | |
| $^{71}$Ga | 31 | 40 | 70.92470255(87) | Stable | Stable | Stable | 3/2− | 0.39892(50) | |
| $^{72}$Ga | 31 | 41 | 71.92636745(88) | 14.025(10) h | β$^−$ | $^{72}$Ge | 3− | | |
| $^{72m}$Ga | 119.66(5) keV | 119.66(5) keV | 119.66(5) keV | 39.68(13) ms | IT | $^{72}$Ga | (0+) | | |
| $^{73}$Ga | 31 | 42 | 72.9251747(18) | 4.86(3) h | β$^−$ | $^{73}$Ge | 1/2− | | |
| $^{73m}$Ga | 0.15(9) keV | 0.15(9) keV | 0.15(9) keV | <200 ms | IT? | $^{73}$Ga | 3/2− | | |
| $^{73m}$Ga | 0.15(9) keV | 0.15(9) keV | 0.15(9) keV | <200 ms | β$^−$ | $^{73}$Ge | 3/2− | | |
| $^{74}$Ga | 31 | 43 | 73.9269457(32) | 8.12(12) min | β$^−$ | $^{74}$Ge | (3−) | | |
| $^{74m}$Ga | 59.571(14) keV | 59.571(14) keV | 59.571(14) keV | 9.5(10) s | IT (>75%) | $^{74}$Ga | (0)(+#) | | |
| $^{74m}$Ga | 59.571(14) keV | 59.571(14) keV | 59.571(14) keV | 9.5(10) s | β$^−$? (<25%) | $^{74}$Ge | (0)(+#) | | |
| $^{75}$Ga | 31 | 44 | 74.92650448(72) | 126(2) s | β$^−$ | $^{75}$Ge | 3/2− | | |
| $^{76}$Ga | 31 | 45 | 75.9288276(21) | 30.6(6) s | β$^−$ | $^{76}$Ge | 2− | | |
| $^{77}$Ga | 31 | 46 | 76.9291543(26) | 13.2(2) s | β$^−$ | $^{77m}$Ge (88%) | 3/2− | | |
| $^{77}$Ga | 31 | 46 | 76.9291543(26) | 13.2(2) s | β$^−$ | $^{77}$Ge (12%) | 3/2− | | |
| $^{78}$Ga | 31 | 47 | 77.9316109(11) | 5.09(5) s | β$^−$ | $^{78}$Ge | 2− | | |
| $^{78m}$Ga | 498.9(5) keV | 498.9(5) keV | 498.9(5) keV | 110(3) ns | IT | $^{78}$Ga | | | |
| $^{79}$Ga | 31 | 48 | 78.9328516(13) | 2.848(3) s | β$^−$ (99.911%) | $^{79}$Ge | 3/2− | | |
| $^{79}$Ga | 31 | 48 | 78.9328516(13) | 2.848(3) s | β$^−$, n (0.089%) | $^{78}$Ge | 3/2− | | |
| $^{80}$Ga | 31 | 49 | 79.9364208(31) | 1.9(1) s | β$^−$ (99.14%) | $^{80}$Ge | 6− | | |
| $^{80}$Ga | 31 | 49 | 79.9364208(31) | 1.9(1) s | β$^−$, n (.86%) | $^{79}$Ge | 6− | | |
| $^{80m}$Ga | 22.45(10) keV | 22.45(10) keV | 22.45(10) keV | 1.3(2) s | β$^−$ | $^{80}$Ge | 3− | | |
| $^{80m}$Ga | 22.45(10) keV | 22.45(10) keV | 22.45(10) keV | 1.3(2) s | β$^−$, n? | $^{79}$Ge | 3− | | |
| $^{80m}$Ga | 22.45(10) keV | 22.45(10) keV | 22.45(10) keV | 1.3(2) s | IT | $^{80}$Ga | 3− | | |
| $^{81}$Ga | 31 | 50 | 80.9381338(35) | 1.217(5) s | β$^−$ (87.5%) | $^{81m}$Ge | 5/2− | | |
| $^{81}$Ga | 31 | 50 | 80.9381338(35) | 1.217(5) s | β$^−$, n (12.5%) | $^{80}$Ge | 5/2− | | |
| $^{82}$Ga | 31 | 51 | 81.9431765(26) | 600(2) ms | β$^−$ (78.8%) | $^{82}$Ge | 2− | | |
| $^{82}$Ga | 31 | 51 | 81.9431765(26) | 600(2) ms | β$^−$, n (21.2%) | $^{81}$Ge | 2− | | |
| $^{82}$Ga | 31 | 51 | 81.9431765(26) | 600(2) ms | β$^−$, 2n? | $^{80}$Ge | 2− | | |
| $^{82m}$Ga | 140.7(3) keV | 140.7(3) keV | 140.7(3) keV | 93.5(67) ns | IT | $^{82}$Ga | (4−) | | |
| $^{83}$Ga | 31 | 52 | 82.9471203(28) | 310.0(7) ms | β$^−$, n (85%) | $^{82}$Ge | 5/2−# | | |
| $^{83}$Ga | 31 | 52 | 82.9471203(28) | 310.0(7) ms | β$^−$ (15%) | $^{83}$Ge | 5/2−# | | |
| $^{83}$Ga | 31 | 52 | 82.9471203(28) | 310.0(7) ms | β$^−$, 2n? | $^{81}$Ge | 5/2−# | | |
| $^{84}$Ga | 31 | 53 | 83.952663(32) | 97.6(12) ms | β$^−$ (55%) | $^{84}$Ge | 0−# | | |
| $^{84}$Ga | 31 | 53 | 83.952663(32) | 97.6(12) ms | β$^−$, n (43%) | $^{83}$Ge | 0−# | | |
| $^{84}$Ga | 31 | 53 | 83.952663(32) | 97.6(12) ms | β$^−$, 2n (1.6%) | $^{82}$Ge | 0−# | | |
| $^{85}$Ga | 31 | 54 | 84.957333(40) | 95.3(10) ms | β$^−$, n (77%) | $^{84}$Ge | (5/2−) | | |
| $^{85}$Ga | 31 | 54 | 84.957333(40) | 95.3(10) ms | β$^−$ (22%) | $^{85}$Ge | (5/2−) | | |
| $^{85}$Ga | 31 | 54 | 84.957333(40) | 95.3(10) ms | β$^−$, 2n (1.3%) | $^{83}$Ge | (5/2−) | | |
| $^{86}$Ga | 31 | 55 | 85.96376(43)# | 49(2) ms | β$^−$, n (69%) | $^{85}$Ge | | | |
| $^{86}$Ga | 31 | 55 | 85.96376(43)# | 49(2) ms | β$^−$, 2n (16.2%) | $^{84}$Ge | | | |
| $^{86}$Ga | 31 | 55 | 85.96376(43)# | 49(2) ms | β$^−$ (15%) | $^{86}$Ge | | | |
| $^{87}$Ga | 31 | 56 | 86.96901(54)# | 29(4) ms | β$^−$, n (81%) | $^{86}$Ge | 5/2−# | | |
| $^{87}$Ga | 31 | 56 | 86.96901(54)# | 29(4) ms | β$^−$, 2n (10.2%) | $^{85}$Ge | 5/2−# | | |
| $^{87}$Ga | 31 | 56 | 86.96901(54)# | 29(4) ms | β$^−$ (9%) | $^{87}$Ge | 5/2−# | | |
| $^{88}$Ga | 31 | 57 | 87.97596(54)# | | β$^−$? | $^{88}$Ge | | | |
| $^{88}$Ga | 31 | 57 | 87.97596(54)# | | β$^−$, n? | $^{87}$Ge | | | |
| $^{89}$Ga | 31 | 58 | | | | | | | |
| This table header & footer: view ||||||||||
* ↑ $^m$Ga – Excited nuclear isomer.
* ↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
* ↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
* ↑ Modes of decay: EC:Electron capture IT:Isomeric transition n:Neutron emission p:Proton emission
* ↑ Bold symbol as daughter – Daughter product is stable.
* ↑ ( ) spin value – Indicates spin with weak assignment arguments.
* ↑ # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
* ↑ Deexcitation gamma used in medical imaging
* ↑ Medically useful radioisotope
* ↑ Order of ground state and isomer is uncertain.

## Gallium-67

Gallium-67 ($^{67}$ Ga ) has a half-life of 3.26 days and decays by electron capture and gamma emission (in de-excitation) to stable zinc-67. It is a radiopharmaceutical used in gallium scans (alternatively, the shorter-lived gallium-68 may be used). This gamma-emitting isotope is imaged by gamma camera.

## Gallium-68

Gallium-68 ($^{68}$ Ga ) is a positron emitter with a half-life of 68 minutes, decaying to stable zinc-68. It is a radiopharmaceutical, generated in situ from the electron capture of germanium-68 (half-life 271 days) owing to its short half-life. This positron-emitting isotope can be imaged efficiently by PET scan (see gallium scan); alternatively, the longer-lived gallium-67 may be used. Gallium-68 is only used as a positron emitting tag for a ligand which binds to certain tissues, such as DOTATOC and DOTATATE, which are somatostatin analogues useful for imaging neuroendocrine tumors. Gallium-68 DOTA scans are increasingly replacing octreotide scans (a type of indium-111 scan using octreotide as a somatostatin receptor ligand). The $^{68}$ Ga is bound to a chemical such as DOTATOC and the positrons it emits are imaged by PET-CT scan. Such scans are useful in locating neuroendocrine tumors and pancreatic cancer. Thus, octreotide scanning for NET tumors is being increasingly replaced by gallium-68 DOTATOC scan.