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Radionuclide Dosimetric Data Sheets
Selenium-81m
Summary data
General
Classification
Isotope: Se-81m
Atomic number (Z): 34
Mass number (A): 81
Neutron number (N): 47
Radioactive decay
Decay modes: β-, Internal transition
Half-life: 57.28 [m]
Decay constant: 2.0168e-04 [1/s]
Daughters: Se-81 (99.9%), Br-81 (0.052%)
Radioactive daughters: Se-81
Dosimetric constants
Mean alpha energy: 0.0 [MeV]
Mean electron energy: 0.0871 [MeV]
Mean photon energy: 0.01834 [MeV]
Air kerma rate constant, Γ10: 1.919e-17 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 1.919e-17 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 1.395e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 0.000e+00
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
1.395e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 2.938e-15
[Gy·kg/Bq·s]
Dose point kernels (plot)
Dose point kernel source: Graves, et al. Medical Physics. 2019 Nov.; 46(11):5284-5293.
Note: Bins are spaced every 0.1 mm until a radius of 10 cm, and every 1 mm until a radius of 2 m.
Download tabulated dose point kernel file here: www.mirdsoft.org/products/MIRDspecs/Se-81m DPK.csv
Summary spectra (plot)
Spectra source: ICRP Publication 107: Nuclear Decay Data for Dosimetric Calculations. Ann. ICRP 2008, 38 (3).
Download tabulated summary spectra file here: www.mirdsoft.org/products/MIRDspecs/Se-81m Summary Spectrum.csv
Beta spectra (plot)
Spectra source: ICRP Publication 107: Nuclear Decay Data for Dosimetric Calculations. Ann. ICRP 2008, 38 (3).
Download tabulated beta spectra file here: www.mirdsoft.org/products/MIRDspecs/Se-81m Beta Spectrum.csv
Tabulated data
Summary spectra (table)
Spectra source: ICRP Publication 107: Nuclear Decay Data for Dosimetric Calculations. Ann. ICRP 2008, 38 (3).
Note: Radiations with yield < 0.01 are excluded from the table, but are available in the linked *.csv data.
Download tabulated summary spectra file here: www.mirdsoft.org/products/MIRDspecs/Se-81m Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
1.58632e-05 |
6.418e+00 |
X-ray |
|
1.11378e-02 |
1.201e-01 |
X-ray |
|
1.11804e-02 |
2.322e-01 |
X-ray |
|
1.24492e-02 |
1.622e-02 |
X-ray |
|
1.24553e-02 |
3.165e-02 |
X-ray |
|
1.03010e-01 |
1.299e-01 |
Gamma |
|
3.25101e-05 |
2.966e+00 |
Auger electron |
|
5.44862e-05 |
1.095e+00 |
Auger electron |
|
9.25860e-05 |
1.658e-01 |
Auger electron |
|
1.23695e-03 |
9.567e-01 |
Auger electron |
|
1.31421e-03 |
4.480e-02 |
Auger electron |
|
9.62662e-03 |
2.162e-01 |
Auger electron |
|
1.09573e-02 |
6.373e-02 |
Auger electron |
|
9.03910e-02 |
6.872e-01 |
Conversion electron |
|
1.01369e-01 |
6.040e-02 |
Conversion electron |
|
1.01529e-01 |
4.913e-02 |
Conversion electron |
|
1.01571e-01 |
6.222e-02 |
Conversion electron |
|
1.02846e-01 |
2.759e-02 |
Conversion electron |
Useful Links
Isotope decay characteristics are periodically updated as better measurements can be made - changes that may not be reflected on this page. Please see useful links:
National Nuclear Data Center (NNDC): https://www.nndc.bnl.gov/nudat3/mird/
International Atomic Energy Agency (IAEA) Livechart: https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html
Reference Links
ICRP Report 107: https://www.icrp.org/publication.asp?id=ICRP%20Publication%20107
Graves et al. Dose Point Kernels: https://doi.org/10.1002/mp.13789
MIRD Decay Schemes 2nd Edition: https://sites.snmmi.org/SNMMI-MAIN/iCore/Store/StoreLayouts/Item_Detail.aspx?iProductCode=0-932004-80-6
MIRDsoft MIRDspecs version 20250101 (www.mirdsoft.org)
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