Isotopes of gallium

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.

Isotopes of gallium (₃₁Ga)

Main isotopes[1] Decay abun­dance half-life (t1/2) mode pro­duct 66Ga synth 9.5 h β+ 66Zn 67Ga synth 3.3 d ε 67Zn 68Ga synth 1.2 h β+ 68Zn 69Ga 60.1% stable 70Ga synth 21 min β− 70Ge ε 70Zn 71Ga 39.9% stable 72Ga synth 14.1 h β− 72Ge 73Ga synth 4.9 h β− 73Ge
Standard atomic weight Ar°(Ga)
	69.723±0.001[2] 69.723±0.001 (abridged)[3]
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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 energy							Normal proportion[1]	Range of variation
60Ga	31	29	59.95750(22)#	72.4(17) ms	β+ (98.4%)	60Zn	(2+)
					β+, p (1.6%)	59Cu
					β+, α? (<0.023%)	56Ni
61Ga	31	30	60.949399(41)	165.9(25) ms	β+	61Zn	3/2−
					β+, p? (<0.25%)	60Cu
62Ga	31	31	61.94418964(68)	116.122(21) ms	β+	62Zn	0+
63Ga	31	32	62.9392942(14)	32.4(5) s	β+	63Zn	3/2−
64Ga	31	33	63.9368404(15)	2.627(12) min	β+	64Zn	0(+#)
64mGa	42.85(8) keV			21.9(7) μs	IT	64Ga	(2+)
65Ga	31	34	64.93273442(85)	15.133(28) min	β+	65Zn	3/2−
66Ga	31	35	65.9315898(12)	9.304(8) h	β+	66Zn	0+
67Ga[n 8]	31	36	66.9282023(13)	3.2617(4) d	EC	67Zn	3/2−
68Ga[n 9]	31	37	67.9279802(15)	67.842(16) min	β+	68Zn	1+
69Ga	31	38	68.9255735(13)	Stable			3/2−	0.60108(50)
70Ga	31	39	69.9260219(13)	21.14(5) min	β− (99.59%)	70Ge	1+
					EC (0.41%)	70Zn
71Ga	31	40	70.92470255(87)	Stable			3/2−	0.39892(50)
72Ga	31	41	71.92636745(88)	14.025(10) h	β−	72Ge	3−
72mGa	119.66(5) keV			39.68(13) ms	IT	72Ga	(0+)
73Ga	31	42	72.9251747(18)	4.86(3) h	β−	73Ge	1/2−
73mGa	0.15(9) keV			<200 ms	IT?	73Ga	3/2−
					β−	73Ge
74Ga	31	43	73.9269457(32)	8.12(12) min	β−	74Ge	(3−)
74mGa	59.571(14) keV			9.5(10) s	IT (>75%)	74Ga	(0)(+#)
					β−? (<25%)	74Ge
75Ga	31	44	74.92650448(72)	126(2) s	β−	75Ge	3/2−
76Ga	31	45	75.9288276(21)	30.6(6) s	β−	76Ge	2−
77Ga	31	46	76.9291543(26)	13.2(2) s	β−	77mGe (88%)	3/2−
						77Ge (12%)
78Ga	31	47	77.9316109(11)	5.09(5) s	β−	78Ge	2−
78mGa	498.9(5) keV			110(3) ns	IT	78Ga
79Ga	31	48	78.9328516(13)	2.848(3) s	β− (99.911%)	79Ge	3/2−
					β−, n (0.089%)	78Ge
80Ga	31	49	79.9364208(31)	1.9(1) s	β− (99.14%)	80Ge	6−
					β−, n (.86%)	79Ge
80mGa[n 10]	22.45(10) keV			1.3(2) s	β−	80Ge	3−
					β−, n?	79Ge
					IT	80Ga
81Ga	31	50	80.9381338(35)	1.217(5) s	β− (87.5%)	81mGe	5/2−
					β−, n (12.5%)	80Ge
82Ga	31	51	81.9431765(26)	600(2) ms	β− (78.8%)	82Ge	2−
					β−, n (21.2%)	81Ge
					β−, 2n?	80Ge
82mGa	140.7(3) keV			93.5(67) ns	IT	82Ga	(4−)
83Ga	31	52	82.9471203(28)	310.0(7) ms	β−, n (85%)	82Ge	5/2−#
					β− (15%)	83Ge
					β−, 2n?	81Ge
84Ga	31	53	83.952663(32)	97.6(12) ms	β− (55%)	84Ge	0−#
					β−, n (43%)	83Ge
					β−, 2n (1.6%)	82Ge
85Ga	31	54	84.957333(40)	95.3(10) ms	β−, n (77%)	84Ge	(5/2−)
					β− (22%)	85Ge
					β−, 2n (1.3%)	83Ge
86Ga	31	55	85.96376(43)#	49(2) ms	β−, n (69%)	85Ge
					β−, 2n (16.2%)	84Ge
					β− (15%)	86Ge
87Ga	31	56	86.96901(54)#	29(4) ms	β−, n (81%)	86Ge	5/2−#
					β−, 2n (10.2%)	85Ge
					β− (9%)	87Ge
88Ga[7]	31	57	87.97596(54)#		β−?	88Ge
					β−, n?	87Ge
89Ga[7]	31	58
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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

• Isotopes of germanium
• Isotopes of zinc
• Isotopes of copper
• Isotopes of nickel