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Radionuclide Dosimetric Data Sheets
Indium-121m
Summary data
General
Classification
Isotope: In-121m
Atomic number (Z): 49
Mass number (A): 121
Neutron number (N): 72
Radioactive decay
Decay modes: β-, Internal transition
Half-life: 3.88 [m]
Decay constant: 2.9774e-03 [1/s]
Daughters: Sn-121 (98.8%), In-121 (1.2%)
Radioactive daughters: Sn-121, In-121
Dosimetric constants
Mean alpha energy: 0.0 [MeV]
Mean electron energy: 1.52876 [MeV]
Mean photon energy: 0.06346 [MeV]
Air kerma rate constant, Γ10: 4.893e-18 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 4.893e-18 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 2.449e-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-:
2.449e-13 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 1.017e-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/In-121m 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/In-121m 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/In-121m 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/In-121m Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
8.12533e-06 |
1.012e-01 |
X-ray |
|
1.08542e-05 |
6.811e+00 |
X-ray |
|
3.43219e-03 |
1.516e-02 |
X-ray |
|
2.50232e-02 |
1.068e-01 |
X-ray |
|
2.52572e-02 |
1.998e-01 |
X-ray |
|
2.84307e-02 |
1.802e-02 |
X-ray |
|
2.84736e-02 |
3.499e-02 |
X-ray |
|
6.01000e-02 |
2.016e-01 |
Gamma |
|
1.04120e+00 |
1.109e-02 |
Gamma |
|
1.04824e+00 |
1.992e-02 |
Beta |
|
1.53536e+00 |
6.971e-01 |
Beta |
|
1.56372e+00 |
2.589e-01 |
Beta |
|
8.85919e-06 |
5.019e-02 |
Auger electron |
|
1.13303e-05 |
3.368e+00 |
Auger electron |
|
3.03730e-05 |
1.157e+00 |
Auger electron |
|
3.35243e-05 |
1.765e-02 |
Auger electron |
|
1.24040e-04 |
3.730e-01 |
Auger electron |
|
2.69839e-04 |
6.530e-02 |
Auger electron |
|
3.70901e-04 |
1.240e-02 |
Auger electron |
|
3.96189e-04 |
8.452e-01 |
Auger electron |
|
4.69765e-04 |
1.924e-02 |
Auger electron |
|
2.84762e-03 |
3.339e-01 |
Auger electron |
|
3.36428e-03 |
8.604e-02 |
Auger electron |
|
2.09334e-02 |
4.026e-02 |
Auger electron |
|
2.44171e-02 |
1.714e-02 |
Auger electron |
|
3.09160e-02 |
4.302e-01 |
Conversion electron |
|
5.56597e-02 |
5.078e-02 |
Conversion electron |
|
5.93897e-02 |
1.096e-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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