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Radionuclide Dosimetric Data Sheets
Thorium-228
Summary data
General
Classification
Isotope: Th-228
Atomic number (Z): 90
Mass number (A): 228
Neutron number (N): 138
Radioactive decay
Decay modes: α
Half-life: 1.912 [y]
Decay constant: 1.1490e-08 [1/s]
Daughters: Ra-224 (100.0%)
Radioactive daughters: Ra-224
Dosimetric constants
Mean alpha energy: 5.4955 [MeV]
Mean electron energy: 0.02101 [MeV]
Mean photon energy: 0.0036 [MeV]
Air kerma rate constant, Γ10: 2.817e-18 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 2.817e-18 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 8.838e-13 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 8.805e-13
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
3.366e-15 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 5.768e-16
[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/Th-228 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/Th-228 Summary 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/Th-228 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
7.12322e-05 |
2.780e+00 |
X-ray |
|
2.89247e-03 |
1.415e-02 |
X-ray |
|
1.23447e-02 |
2.916e-02 |
X-ray |
|
1.53013e-02 |
3.877e-02 |
X-ray |
|
8.43730e-02 |
1.220e-02 |
Gamma |
|
2.57928e-05 |
7.637e-01 |
Auger electron |
|
1.20879e-04 |
7.735e-01 |
Auger electron |
|
1.81417e-04 |
4.410e-01 |
Auger electron |
|
4.75906e-04 |
1.112e-01 |
Auger electron |
|
2.11564e-03 |
1.391e-02 |
Auger electron |
|
2.22754e-03 |
2.440e-01 |
Auger electron |
|
2.60262e-03 |
3.938e-02 |
Auger electron |
|
9.56022e-03 |
6.606e-02 |
Auger electron |
|
1.24985e-02 |
3.209e-02 |
Auger electron |
|
6.58130e-02 |
1.072e-01 |
Conversion electron |
|
6.89170e-02 |
8.276e-02 |
Conversion electron |
|
8.05993e-02 |
5.283e-02 |
Conversion electron |
|
8.43730e-02 |
1.784e-02 |
Conversion electron |
|
5.34032e+00 |
2.718e-01 |
Alpha |
|
5.42321e+00 |
7.214e-01 |
Alpha |
|
9.54249e-02 |
2.718e-01 |
Alpha recoil |
|
9.69061e-02 |
7.214e-01 |
Alpha recoil |
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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