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Radionuclide Dosimetric Data Sheets
Iodine-120m
Summary data
General
Classification
Isotope: I-120m
Atomic number (Z): 53
Mass number (A): 120
Neutron number (N): 67
Radioactive decay
Decay modes: β+, Electron capture
Half-life: 53.0 [m]
Decay constant: 2.1797e-04 [1/s]
Daughters: Te-120 (100.0%)
Radioactive daughters: None
Dosimetric constants
Mean alpha energy: 0.0 [MeV]
Mean electron energy: 0.90697 [MeV]
Mean photon energy: 3.52483 [MeV]
Air kerma rate constant, Γ10: 1.007e-16 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 1.275e-16 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 1.453e-13 [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-:
1.453e-13 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 5.647e-13
[Gy·kg/Bq·s]
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-120m 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-120m 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-120m Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
1.36107e-05 |
4.144e+00 |
X-ray |
|
3.75695e-03 |
1.096e-02 |
X-ray |
|
2.71868e-02 |
6.991e-02 |
X-ray |
|
2.74652e-02 |
1.301e-01 |
X-ray |
|
3.09378e-02 |
1.198e-02 |
X-ray |
|
3.09901e-02 |
2.324e-02 |
X-ray |
|
4.25700e-01 |
2.800e-02 |
Gamma |
|
4.77900e-01 |
1.200e-02 |
Gamma |
|
4.85100e-01 |
1.200e-02 |
Gamma |
|
5.11000e-01 |
1.383e+00 |
Annihilation photon |
|
5.60400e-01 |
1.000e+00 |
Gamma |
|
6.01100e-01 |
8.700e-01 |
Gamma |
|
6.14700e-01 |
3.100e-02 |
Gamma |
|
6.14700e-01 |
6.400e-01 |
Gamma |
|
6.41100e-01 |
1.500e-02 |
Gamma |
|
6.54500e-01 |
2.100e-02 |
Gamma |
|
7.03900e-01 |
1.900e-02 |
Gamma |
|
8.74700e-01 |
1.000e-02 |
Gamma |
|
8.81800e-01 |
2.200e-02 |
Gamma |
|
9.21300e-01 |
4.300e-02 |
Gamma |
|
1.03150e+00 |
1.500e-02 |
Gamma |
|
1.03990e+00 |
6.500e-02 |
Gamma |
|
1.05920e+00 |
5.100e-02 |
Gamma |
|
1.15800e+00 |
2.700e-02 |
Gamma |
|
1.19730e+00 |
2.300e-02 |
Gamma |
|
1.26130e+00 |
1.700e-02 |
Gamma |
|
1.33460e+00 |
4.400e-02 |
Gamma |
|
1.34590e+00 |
1.890e-01 |
Gamma |
|
1.40500e+00 |
9.300e-02 |
Gamma |
|
1.44110e+00 |
1.300e-02 |
Gamma |
|
1.52300e+00 |
1.050e-02 |
Gamma |
|
1.85140e+00 |
1.600e-02 |
Gamma |
|
1.86830e+00 |
3.800e-02 |
Gamma |
|
1.92280e+00 |
2.000e-02 |
Gamma |
|
1.98820e+00 |
2.300e-02 |
Gamma |
|
2.30540e+00 |
2.000e-02 |
Gamma |
|
2.56060e+00 |
3.700e-02 |
Gamma |
|
2.86430e+00 |
2.300e-02 |
Gamma |
|
3.10510e+00 |
2.100e-02 |
Gamma |
|
8.02418e-01 |
1.267e-01 |
Positron |
|
1.22457e+00 |
3.553e-02 |
Positron |
|
1.42275e+00 |
5.253e-01 |
Positron |
|
2.29233e-05 |
2.025e+00 |
Auger electron |
|
2.49267e-05 |
6.762e-01 |
Auger electron |
|
1.21039e-04 |
2.329e-01 |
Auger electron |
|
2.95093e-04 |
4.296e-02 |
Auger electron |
|
4.49467e-04 |
5.214e-01 |
Auger electron |
|
5.41108e-04 |
2.009e-02 |
Auger electron |
|
3.08422e-03 |
2.048e-01 |
Auger electron |
|
3.67827e-03 |
5.799e-02 |
Auger electron |
|
2.26653e-02 |
2.259e-02 |
Auger 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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