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Radionuclide Dosimetric Data Sheets
Iodine-131
Summary data
General
Classification
Isotope: I-131
Atomic number (Z): 53
Mass number (A): 131
Neutron number (N): 78
Radioactive decay
Decay modes: β-
Half-life: 8.021 [d]
Decay constant: 1.0002e-06 [1/s]
Daughters: Xe-131m (1.18%), Xe-131 (98.8%)
Radioactive daughters: Xe-131m
Dosimetric constants
Mean alpha energy: 0.0 [MeV]
Mean electron energy: 0.19184 [MeV]
Mean photon energy: 0.38275 [MeV]
Air kerma rate constant, Γ10: 1.452e-17 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 1.452e-17 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 3.074e-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-:
3.074e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 6.132e-14
[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/I-131 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/I-131 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/I-131 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/I-131 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
1.66175e-05 |
7.627e-01 |
X-ray |
|
2.94521e-02 |
1.401e-02 |
X-ray |
|
2.97812e-02 |
2.594e-02 |
X-ray |
|
8.01850e-02 |
2.623e-02 |
Gamma |
|
2.84305e-01 |
6.136e-02 |
Gamma |
|
3.64489e-01 |
8.170e-01 |
Gamma |
|
6.36989e-01 |
7.173e-02 |
Gamma |
|
7.22911e-01 |
1.773e-02 |
Gamma |
|
6.93474e-02 |
2.091e-02 |
Beta |
|
9.65904e-02 |
7.237e-02 |
Beta |
|
1.91529e-01 |
8.950e-01 |
Beta |
|
2.61504e-05 |
1.187e-01 |
Auger electron |
|
3.62367e-05 |
3.628e-01 |
Auger electron |
|
1.23806e-04 |
4.455e-02 |
Auger electron |
|
5.05029e-04 |
9.966e-02 |
Auger electron |
|
3.32402e-03 |
3.930e-02 |
Auger electron |
|
4.00104e-03 |
1.166e-02 |
Auger electron |
|
4.56290e-02 |
3.553e-02 |
Conversion electron |
|
3.29933e-01 |
1.563e-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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