The CLRP TG-43 Parameter Database for Low-Energy Brachytherapy, version 2

H. Safigholi, M. J. P. Chamberland, R. E. P. Taylor, C. H. Allen, M. P. Martinov,

D. W. O. Rogers, and R. M. Thomson


The information contained in this CLRP TG-43 parameter database is provided for research and educational purposes only and must not be directly used for clinical applications, unless explicitly recommended for clinical use by the appropriate professional body (e.g., AAPM).

About the CLRPv2 Database

This is the home of version 2 (v2) of the Carleton Laboratory for Radiotherapy Physics (CLRP) Database of TG-43 brachytherapy dosimetry parameters 1-3. The dosimetry parameters presented here were calculated using the EGSnrc application egs_brachy, a Monte Carlo code for doing rapid brachytherapy dose calculations 4.

On these pages you will find a set of TG-43 dosimetry parameters for most of the brachytherapy sources listed in the Joint AAPM/RPC brachytherapy source registryThe aim of the present work is to create a comprehensive updated database of TG-43 dosimetry parameters using  consistent methods for all sources. These data are made freely available to the public and we hope it will prove to be a valuable resource for the medical physics community.

CLRPv2 includes the TG-43 source information and mean photon energy for 40 low-energy LDR sources (17 103Pd, 22 125I, and 1 131Cs). In the future, it will include source information for HDR sources. The half-lives (τ1/2) of 103Pd, 125I, and 131Cs LDR sources  reported by the BIPM are 16.964(10), 59.388(28) and 9.69(1)  days, respectively 5. The half-lives of 103Pd, 125I, and 131Cs LDR sources reported by TG-43U1S2 6 are 16.991(34), 59.407 (10), and 9.689 (1) days, respectively.  Initial  photon energies and probabilities are sampled from the NNDC  spectra 7 for 103Pd and 131Cs sources. For 125I, the photon spectrum from NCRP Report 58 8 is used since it has been demonstrated that using the NCRP spectrum leads to better agreement with measured spectra for many seeds 9 and is consistent with the spectrum recommended by the BIPM for use by primary standards labs 5Average photon energy of the initial bare spectra used here are 18.89, 28.39 and 27.61 keV for 103Pd, 125I, and 131Cs radionuclides, respectively.  These average enegies include lines below 5 keV. Without those lines the average energies are 20.72, 28.39 and 30.38 keV respectively.

Average photon energies are reported for each source. These are the average energies of photons escaping the surface of the source.

Photon energy spectra calculated using egs_brachy surface count scoring option to get the spectrum on the surface of the source for three representive LDR sources are shown here. The relative counts is the counts per 0.1 keV bin per MeV normalized to 1 count total in the spectrum.

Click images for higher res versions
 103Pd (200) photon energy spectra 
125I (6711) photon energy spectra 


125I (130.002) photon energy spectra


131Cs (CS-1 Rev2) photon energy spectra


The voxel resolutions used with egs_brachy to calculate the TG-43 data are 0.1 mm for r ≤ 1 cm, 0.5 mm for 1 cm < r ≤ 5 cm, 1 mm for  5 cm < r ≤ 10 cm, and 2 mm for  r > 10 cm.

Air-kerma strength per history factors, SKhist, for all CLRPv2 low energy seeds is here Sis scored in vacuo using a scoring voxel located on the transverse axis 10 cm away from the source and size of 2.66×2.66×0.05 cm3 representing the solid angle of the WAFAC detector.

The egs_brachy source models used to create this database will be made available as part of the egs_brachy distribution at

Users of this database may also find other useful information on the CLRP Links page.

Brachytherapy Source Data:

For the current list of sources covered by TG-43 and the Joint AAPM/RPC brachytherapy source registry please visit the RPC website. Listings marked by an asterisk (*) indicate a source that was not on the previous version of the CLRP TG-43 Parameter Database.

125I LDR Seeds:

103Pd LDR Seeds:

131Cs LDR Seeds:


We ask that anyone using data found on this web page to please cite our following report on this dataset published by Medical Physics.

H. Safigholi, M. J. P. Chamberland, R. E. P. Taylor, C. H. Allen, M. P. Martinov, D. W. O. Rogers, and R. M. Thomson, Update of the CLRP TG-43 parameter database for low-energy brachytherapy sources,  Med phys., 47, 4556-4669 (2020)



1. R. E. P. Taylor, D. W. O. Rogers, An EGSnrc Monte Carlo-calculated database of TG-43 parameters, Med. Phys., 35, 4228-4241, 2008
2. R. E. P. Taylor, D. W. O. Rogers, More accurate fitting of 125I and 103Pd radial dose functions, Med. Phys., 35, 4242-4250, 2008
3. H. Safigholi, M. J. P. Chamberland, R. E. P. Taylor, C. H. Allen, M. P. Martinov, D. W. O. Rogers, and R. M. Thomson, Update of the CLRP TG-43 parameter database for low-energy brachytherapy sources,  Med phys., 47, 4556-4669 (2020)
4. M Chamberland, RE Taylor, DWO Rogers, RM Thomson, egs_brachy: a versatile and fast Monte Carlo code for brachytherapy, Phys. Med. Biol., 23, 8214-8231, 2016
5. BIPM,  Monographie BIPM-5:  Table of Radionuclides:  Vol 6,  Technical report, BIPM, Sevres, France:, 2011         
6. M. J. Rivard et al ,  Supplement 2 for the 2004 update of the AAPM Task Group No. 43 Report: Joint recommendations by the AAPM and GEC-ESTRO, Med. Phys., 44 , e297-e338, 2017.
7.Brookhaven National Laboratory, National Nuclear Data Center,
8.NCRP  Report  58, A  Handbook  of  Radioactivity  Measurements  Procedures,   NCRP674Publications, 7910 Woodmont Avenue, Bethesda, MD. 20814 USA (1985)     
9.  M. Rodriguez and D. W. O. Rogers,   On determining dose rate constants spectroscopically,  Med. Phys.40, 011713 (10pp) (2013)


Contact Information:

If you would like to know more about the CLRP TG-43 Database or to report problems, please contact:

David Rogers          E-mail: drogersatphysics [dot] carleton [dot] ca
Rowan Thomson    E-mail: rthomsonatphysics [dot] carleton [dot] ca
These pages were originally set up by Randy Taylor and Marc Chamberland and extensively updated by Habib Safigholi.

Important Note

The previous version of the CLRP TG-43 database (CLRP-TG43v1) is available here for archival purposes.

CLRP TG-43 Parameter Database V2

May 5, 2020. 


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