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Radionuclide Dosimetric Data Sheets
Technetium-99m
Summary data
General
Classification
Isotope: Tc-99m
Atomic number (Z): 43
Mass number (A): 99
Neutron number (N): 56
Radioactive decay
Decay modes: β-, Internal transition
Half-life: 6.015 [h]
Decay constant: 3.2010e-05 [1/s]
Daughters: Tc-99 (100.0%), Ru-99 (0.0037%)
Radioactive daughters: Tc-99
Dosimetric constants
Mean alpha energy: 0.0 [MeV]
Mean electron energy: 0.01618 [MeV]
Mean photon energy: 0.12659 [MeV]
Air kerma rate constant, Γ10: 5.109e-18 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 5.109e-18 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 2.592e-15 [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-:
2.592e-15 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 2.028e-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/Tc-99m 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/Tc-99m 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/Tc-99m 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/Tc-99m Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
7.87678e-06 |
5.497e+00 |
X-ray |
|
1.82141e-02 |
2.135e-02 |
X-ray |
|
1.83344e-02 |
4.059e-02 |
X-ray |
|
1.40511e-01 |
8.906e-01 |
Gamma |
|
2.96081e-05 |
2.466e+00 |
Auger electron |
|
1.06317e-04 |
2.075e-02 |
Auger electron |
|
1.14154e-04 |
7.088e-01 |
Auger electron |
|
2.06128e-04 |
1.084e+00 |
Auger electron |
|
1.74765e-03 |
8.625e-01 |
Conversion electron |
|
2.05392e-03 |
9.032e-02 |
Auger electron |
|
2.17260e-03 |
1.296e-01 |
Conversion electron |
|
2.33269e-03 |
1.407e-02 |
Auger electron |
|
1.54229e-02 |
1.479e-02 |
Auger electron |
|
1.19499e-01 |
8.916e-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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