Thulium-170

Isotope of thulium

Thulium-170, 170TmGeneral

Symbol| 170Tm
Names| Thulium-170, 170Tm, Tm-170
Protons (Z)| 69
Neutrons (N)| 101
Nuclide data
Natural abundance| Synthetic
Half-life (t1/2)| 128.6±0.3 d[1]
Isotope mass| 169.935807093(785)[1] Da
Spin| 1−[1]
Binding energy| 1377937.45±0.73[1] keV
Decay products| 170Yb
170Er
Decay modes
Decay mode| Decay energy (MeV)
β−| 0.8838, 0.9686[2]
EC| 0.2341, 0.3122[2]
Isotopes of thulium
Complete table of nuclides

Thulium-170 (170Tm or Tm-170) is a radioactive isotope of thulium proposed for use in radiotherapy and in radioisotope thermoelectric generators.

## Properties[edit]

Thulium-170 has a binding energy of 8105.5144(43) keV per nucleon and a half-life of 128.6±0.3 d. It decays by β− decay to 170Yb about 99.869% of the time, and by electron capture to 170Er about 0.131% of the time.[1] About 18.1% of β− decays populate a narrow excited state of 170Yb at 84.25474(8) keV (t1/2 = 1.61 ± 0.02 ns), and this is the main X-ray emission from 170Tm; lower bands are also produced through X-ray fluorescence at 7.42, 51.354, 52.389, 59.159, 59.383, and 60.962 keV.[2][3]

The ground state of thulium-170 has a spin of 1−. The charge radius is 5.2303(36) fm, the magnetic moment is 0.2458(17) μN, and the electric quadrupole moment is 0.72(5) e⋅b.[4]

## Proposed applications[edit]

As a rare-earth element, thulium-170 can be used as the pure metal or thulium hydride, but most commonly thulium oxide due to the refractory properties of that compound.[5][6] The isotope can be prepared in a medium-strength reactor by neutron irradiation of natural thulium, which has a high neutron capture cross section of 103 barns.[3][6]

### Medicine[edit]

In 1953, the Atomic Energy Research Establishment introduced thulium-170 as a candidate for radiography in medical and steelmaking contexts,[7] but this was deemed unsuitable due to the predominant high-energy bremsstrahlung radiation, poor results on thin specimens, and long exposure times.[8] However, 170Tm has been proposed for radiotherapy because the isotope is simple to prepare into a biocompatible form, and the low-energy radiation can selectively irradiate diseased tissue without causing collateral damage.[3][9]

### Radiothermal generator[edit]

As the oxide (Tm2O3), thulium-170 has been proposed as a radiothermal source due to it being safer, cheaper, and more environmentally friendly than commonly used isotopes such as plutonium-238.[10][11] The heat output from a 170Tm source is initially much greater than from a 238Pu source relative to mass, but it declines rapidly due to its shorter half-life.[6]

## References[edit]

1. ^ a b c d e Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
2. ^ a b c d "NuDat 3". www.nndc.bnl.gov.
3. ^ a b c d Polyak, Andras; Das, Tapas; Chakraborty, Sudipta; Kiraly, Reka; Dabasi, Gabriella; Joba, Robert Peter; Jakab, Csaba; Thuroczy, Julianna; Postenyi, Zita; Haasz, Veronika; Janoki, Gergely; Janoki, Gyozo A.; Pillai, Maroor R.A.; Balogh, Lajos (October 2014). "Thulium-170-Labeled Microparticles for Local Radiotherapy: Preliminary Studies". Cancer Biotherapy and Radiopharmaceuticals. 29 (8): 330–338. doi:10.1089/cbr.2014.1680. ISSN 1084-9785. PMID 25226213 - via Academia.edu.
4. ^ Mertzimekis, Theo J. "NUMOR | Nuclear Moments and Radii | University of Athens | since 2007". magneticmoments.info. Retrieved 12 November 2023.
5. ^ a b Walter, C.E.; Van Konynenburg, R.; VanSant, J.H. (6 September 1990). "Thulium-170 heat source". doi:10.2172/10156110. OSTI 10156110.
6. ^ a b c d Dustin, J. Seth; Borrelli, R.A. (December 2021). "Assessment of alternative radionuclides for use in a radioisotope thermoelectric generator". Nuclear Engineering and Design. 385: 111475. doi:10.1016/j.nucengdes.2021.111475. S2CID 240476644.
7. ^ Hilbish, Theodore F. (November 1954). "Developments in diagnostic radiology". Public Health Reports. 69 (11): 1017–1027. doi:10.2307/4588947. ISSN 0094-6214. JSTOR 4588947. PMC 2024396. PMID 13215708.
8. ^ a b Halmshaw, Ronald (1995). Industrial radiology: theory and practice (2. ed.). London: Chapman & Hall. pp. 59–60. ISBN 0412627809.
9. ^ a b Vats, Kusum; Das, Tapas; Sarma, Haladhar D.; Banerjee, Sharmila; Pillai, M.r.a. (December 2013). "Radiolabeling, Stability Studies, and Pharmacokinetic Evaluation of Thulium-170-Labeled Acyclic and Cyclic Polyaminopolyphosphonic Acids" (PDF). Cancer Biotherapy and Radiopharmaceuticals. 28 (10): 737–745. doi:10.1089/cbr.2013.1475. ISSN 1084-9785. PMID 23931111. Archived from the original (PDF) on 2023-11-12.
10. ^ a b Walter, C. E. (1 July 1991). "Infrastructure for thulium-170 isotope power systems for autonomous underwater vehicle fleets". Lawrence Livermore National Lab., CA (United States). OSTI 5491258.
11. ^ Alderman, Carol J. (1993). "Thulium heat sources for space power application". AIP Conference Proceedings. Vol. 271\. pp. 1085–1091. doi:10.1063/1.43194.

Lighter:
thulium-169 | Thulium-170 is an
isotope of thulium | Heavier:
thulium-171

|
|

Decay product of:
— | Decay chain
of thulium-170  | Decays to:
erbium-170
ytterbium-170