Isotopes of gallium

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Isotopes of gallium  (31Ga)
Main isotopes [1] Decay
Isotope abun­dance half-life (t1/2) mode pro­duct
66Ga synth 9.5 h β+ 66Zn
67Gasynth3.3 d ε 67Zn
68Gasynth1.2 hβ+ 68Zn
69Ga60.1% stable
70Gasynth21 min β 70Ge
ε 70Zn
71Ga39.9%stable
72Gasynth14.1 hβ 72Ge
73Gasynth4.9 hβ 73Ge
Standard atomic weight Ar°(Ga)

Natural gallium (31Ga) 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, 64mGa, 72mGa and 74mGa. 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.

Contents

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, Ga3+. 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 68Zn in low-energy medical cyclotrons, [4] [5] 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 67Ga radioisotope normally used in standard gallium scans.

List of isotopes


Nuclide
[n 1]
Z N Isotopic mass (Da) [6]
[n 2] [n 3]
Half-life [1]
Decay
mode
[1]
[n 4]
Daughter
isotope

[n 5]
Spin and
parity [1]
[n 6] [n 7]
Natural abundance (mole fraction)
Excitation energyNormal proportion [1] Range of variation
59Ga3128
60Ga312959.95750(22)#72.4(17) ms β+ (98.4%)60Zn(2+)
β+, p (1.6%)59Cu
β+, α? (<0.023%)56Ni
61Ga313060.949399(41)165.9(25) msβ+61Zn3/2−
β+, p? (<0.25%)60Cu
62Ga313161.94418964(68)116.122(21) msβ+62Zn0+
63Ga313262.9392942(14)32.4(5) sβ+63Zn3/2−
64Ga313363.9368404(15)2.627(12) minβ+64Zn0(+#)
64mGa42.85(8) keV21.9(7) μsIT64Ga(2+)
65Ga313464.93273442(85)15.133(28) minβ+65Zn3/2−
66Ga313565.9315898(12)9.304(8) hβ+66Zn0+
67Ga [n 8] 313666.9282023(13)3.2617(4) d EC 67Zn3/2−
68Ga [n 9] 313767.9279802(15)67.842(16) minβ+68Zn1+
69Ga313868.9255735(13)Stable3/2−0.60108(50)
70Ga313969.9260219(13)21.14(5) minβ (99.59%)70Ge1+
EC (0.41%)70Zn
71Ga314070.92470255(87)Stable3/2−0.39892(50)
72Ga314171.92636745(88)14.025(10) hβ72Ge3−
72mGa119.66(5) keV39.68(13) ms IT 72Ga(0+)
73Ga314272.9251747(18)4.86(3) hβ73Ge1/2−
73mGa0.15(9) keV<200 msIT?73Ga3/2−
β73Ge
74Ga314373.9269457(32)8.12(12) minβ74Ge(3−)
74mGa59.571(14) keV9.5(10) sIT (>75%)74Ga(0)(+#)
β? (<25%)74Ge
75Ga314474.92650448(72)126(2) sβ75Ge3/2−
76Ga314575.9288276(21)30.6(6) sβ76Ge2−
77Ga314676.9291543(26)13.2(2) sβ77mGe (88%)3/2−
77Ge (12%)
78Ga314777.9316109(11)5.09(5) sβ78Ge2−
78mGa498.9(5) keV110(3) nsIT78Ga
79Ga314878.9328516(13)2.848(3) sβ (99.911%)79Ge3/2−
β, n (0.089%)78Ge
80Ga314979.9364208(31)1.9(1) sβ (99.14%)80Ge6−
β, n (.86%)79Ge
80mGa [n 10] 22.45(10) keV1.3(2) sβ80Ge3−
β, n?79Ge
IT80Ga
81Ga315080.9381338(35)1.217(5) sβ (87.5%)81mGe5/2−
β, n (12.5%)80Ge
82Ga315181.9431765(26)600(2) msβ (78.8%)82Ge2−
β, n (21.2%)81Ge
β, 2n?80Ge
82mGa140.7(3) keV93.5(67) nsIT82Ga(4−)
83Ga315282.9471203(28)310.0(7) msβ, n (85%)82Ge5/2−#
β (15%)83Ge
β, 2n?81Ge
84Ga315383.952663(32)97.6(12) msβ (55%)84Ge0−#
β, n (43%)83Ge
β, 2n (1.6%)82Ge
85Ga315484.957333(40)95.3(10) msβ, n (77%)84Ge(5/2−)
β (22%)85Ge
β, 2n (1.3%)83Ge
86Ga315585.96376(43)#49(2) msβ, n (69%)85Ge
β, 2n (16.2%)84Ge
β (15%)86Ge
87Ga315686.96901(54)#29(4) msβ, n (81%)86Ge5/2−#
β, 2n (10.2%)85Ge
β (9%)87Ge
88Ga [7] 315787.97596(54)#β?88Ge
β, n?87Ge
89Ga [7] 3158
This table header & footer:
  1. mGa  Excited nuclear isomer.
  2. ()  Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
  3. #  Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
  4. Modes of decay:
    EC: Electron capture
    IT: Isomeric transition
    n: Neutron emission
    p: Proton emission
  5. Bold symbol as daughter  Daughter product is stable.
  6. () spin value  Indicates spin with weak assignment arguments.
  7. #  Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
  8. Deexcitation gamma used in medical imaging
  9. Medically useful radioisotope
  10. 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, [8] 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. [9] Thus, octreotide scanning for NET tumors is being increasingly replaced by gallium-68 DOTATOC scan. [10]

See also

Daughter products other than gallium

References

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  8. Chauhan, Aman; El-Khouli, Riham; Waits, Timothy; Agrawal, Rohitashva; Siddiqui, Fariha; Tarter, Zachary; Horn, Millicent; Weiss, Heidi; Oates, Elizabeth; Evers, B. Mark; Anthony, Lowell (2020-08-11). "Post FDA approval analysis of 200 gallium-68 DOTATATE imaging: A retrospective analysis in neuroendocrine tumor patients". Oncotarget. 11 (32): 3061–3068. doi:10.18632/oncotarget.27695. ISSN   1949-2553. PMC   7429177 . PMID   32850010.
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