The BRAchytherapy PHYsics Quality Assurance System (BRAPHYQS) working group of GEC-ESTRO was originally created under the ESQUIRE Project funded by the European Commission (Grant Agreement S12.322029 (2001CVG2-005) and SPC.2002480). The ESQUIRE Project ended in December 2003. The BRAPHYQS working group was in charge of Task 6 of the ESQUIRE project. One of the outputs was the publication of the ESTRO Booklet number 8 "A Practical Guide To Quality Control Of Brachytherapy Equipment". BRAPHYQS is supported by ESTRO and receives sponsorship from industry for its meetings. Since then BRAPHYQS works on different working packages in brachytherapy physics. Results are published in peer-reviewed journals. Typically two working meetings per year are organized to support the project work. Some of the working packages have involvement of other societies as AAPM or ABG.

BRAPHYQS has been involved in:


  • AAPM/ESTRO/ABG WGBDCA: Model-based-dose-calculation algorithm working group (Chair: Javier Vijande).
  • AAPM/ESTRO TG-236: Recommendations on 3D Image-based Treatment Planning, Dosimetry and Quality Management for Intracavitary Brachytherapy (Chair: Yongbok Kim).
  • AAPM/ESTRO TG-253: Surface Brachytherapy (Co-chairs: Regina K Fulkerson and José Pérez-Calatayud)
  • AAPM/ESTRO TG-267: Biophysical models and tools for the planning and evaluation of selected brachytherapy modalities (Chair: Zhe (Jay) Chen).
    • AAPM/ESTRO TG-317:  Catheter, Needle, and Applicator Tracking Technology in Brachytherapy (Chairs Luc Beaulieu, Adam Cunha)
    • EMPIR: (Primary standards and Traceable measurement methods for x-ray emitting electronic brachytherapy and IORT devices)


  • Euramet Research Project (SRT-h14): Metrology for Radiotherapy in Complex Radiation Fields.
  • AAPM/ESTRO HEBD WG: Working group on High Energy Brachytherapy Dosimetry working group (Chair: José Pérez-Calatayud. Finalised summer 2012).
  • AAPM/ESTRO/ABG/ABS TG-186: Model-based Dose Calculation Techniques in Brachytherapy: Status and Clinical Requirements for Implementation Beyond AAPM TG-43 (Chair Luc Beaulieu. Finalised September 2012).
  • Euramet T2.J06 project (as Guest): Increasing cancer treatment efficacy using 3D brachytherapy (Finalised summer 2012).
  • AAPM/ESTRO TG-192: Image-Guided Robotic Brachytherapy (Chair: Tarun Podder).
  • AAPM/ESTRO TG-167: Recommendations on Dosimetry Requirements for Investigational Sources for Interstitial Brachytherapy (Chair: Ravinder Nath)
  • AAPM/ESTRO TG-U1S2: Unit No.25 Supplement 2 to the 2004 update of the AAPM TG-43 Report: A joint report of the AAPM and GEC-ESTRO (Chair: Mark J. Rivard) see also Erratum.

Purpose and background

To address the limited availability of radiation shielding data for brachytherapy as well as some disparity in existing data, Monte Carlo simulation was used to generate radiation transmission data for 60Co, 137Cs, 198Au, 192Ir, 169Yb, 170Tm, 131Cs, 125I and 103Pd photons through concrete, stainless steel, lead, as well as lead glass and barite concrete. This data can be easily and accurately used for shielding design purposes using the values of a three-parameter empirical fit that are also provided for every radionuclide-material combination. This work is extensively described in a paper published in Medical Physics (2008) [1], including details of the MC simulation as well as a comparison with previous results in the literature [2-5].In addition to the material published in this paper, the present web pages can be and will be further updated to include information on other brachytherapy radionuclides and other shielding materials aiming at providing a useful and comprehensive set of data for brachytherapy facility shielding.

Monte Carlo code

The GEANT4 code v.7 was employed for MC simulations in this work using the EPDL97 cross section libraries. The MCNPX code v. 2.4.0 was also used in simulations for selected radionuclide-material combinations as an independent check. Results of the two codes were found in close agreement and results presented here correspond to the GEANT4 simulations.

Monte Carlo geometry

The simulation geometry is shown on this page and comprised an air filled box of x×y×z  = 5×5×3 m3dimensions with the source of a chosen radionuclide centred on the yz plane at x=0 and a barrier of given material and thickness ∆x positioned with its distal surface to the source at x=1 m. The same geometry was used for all radionuclide-shielding material combinations with photons emitted isotropically in a 2π solid angle towards the barrier to simulate broad beam conditions in a realistic geometry. Transmission was scored 30 cm behind the barrier which is consistent with the practise of NCRP Reports [5, 6]. The percentage elemental composition and density of all materials are presented in Table I of the original work.


Source description

Bare point sources were simulated for each of the radionuclides studied in this work. The emitted photon spectrum of the radionuclides was taken by NuDat 2.4, excluding photon lines of energy lower than 10 keV that would be strongly absorbed by the core and encapsulation of real source designs. It must be noted that bremsstrahlung production due to the beta emissions of 170Tm was not taken into account. This latter decision was taken as no construction details of a source containing 170Tm were known to the authors. For a real source design with 170Tm this calculation should be repeated.

Presentation of the data

Results are shown in the form of tables with the numerical data of each combination of radionuclide and shielding material.

These tables include the thickness of the shielding material, the transmission factor, the estimated uncertainty and the outcome of a 3-parameter fitted model of each combination.

A graphical presentation in four decades of the transmission factor is directly available for each combination of radionuclide and shielding material, obtained by selection of the desired combination.

Fitting procedure

The three-parameter model introduced by Archer et al (1983) [7] to facilitate diagnostic x-ray shielding calculations was used to describe transmission results of this study. The equation of this model has the form:

where stands for transmission, is the thickness of the shielding barrier (denoted by ∆in the description of the simulation geometry in the previous section) and α, β, γ are constant terms to be determined by the fit and depend on photon energy as well as the barrier material. The barrier thickness to achieve a given transmission can be calculated by solving this equation for which yields:

At large barrier thickness, x, transmission tends to exp(-αx) according to the first equation and α is the slope of the transmission curve beyond the depth where the relative directional and energy photon distributions are almost independent of thickness. Here, equilibrium HVL and TVL values, HVLe and TVLe, can be calculated as ln2/α and ln10/α, respectively.


Click on the materials to find transmission data for all radionuclides:


The work described in this paper was performed within the framework of the GEC-ESTRO working group BRAPHYQS working group  (BRAchytherapy PHYsics Quality assurance System) physicists’ network. BRAPHYQS members are deeply acknowledged for their contributions to the discussions on this topic. Companies supporting the meetings of BRAPHYQS are acknowledged for their financial support: Oncura, Varian, and Nucletron.


For a more complete list >>>

  1. P. Papagiannis, D. Baltas, D. Granero, J. Pérez-Calatayud, J. Gimeno, F. Ballester, J. L. M. Venselaar. “Radiation transmission data for radionuclides and materials relevant to brachytherapy facility shielding”. Med. Phys. Vol. 35 (11), November 2008 4898-4906

  2. NCRP (National Council on Radiological Protection and Measurements) 1976. “Structural Shielding Design and Evaluation for Medical Use of X Rays and Gamma Rays of up to 10 MeV”. NCRP Report No. 49 (Washington, DC: NCRP).

  3. D. Delacroix, J. P. Guerre, P. Leblanc, and C. Hickman. “Radionuclide and Radiation Protection Data Handbook”. Rad. Prot. Dos. 98, 1–168 (2002).

  4. IAEA (International Atomic Energy Agency) 2006. “Radiation Protection in the Design of Radiotherapy Facilities”. Safety Reports Series No. 47 (Vienna: IAEA).

  5. NCRP (National Council on Radiological Protection and Measurements) (2005). “Structural shielding design and evaluation for megavoltage X- and gamma-ray radiotherapy facilities”. NCRP Report No. 151 (Washington, DC: NCRP).

  6. NCRP (National Council on Radiological Protection and Measurements) 2007. “Management of Radionuclide Therapy Patients”. NCRP Report No. 155 (Washington, 360 DC: NCRP).

  7. B.J. Archer, J.I. Thornby, and S.C. Bushong. “Diagnostic x-ray shielding design based on an empirical model of photon attenuation”. Health Phys. 44, 507–517 (1983).

A database of TG-43 dosimetry parameters of brachytherapy seeds/sources is stored at the Joint AAPM/IROC Houston Registry of Brachytherapy Sources webpage. All sources in this registry have direct or indirect traceability to the air-kerma strength standards maintained by accredited calibrations laboratories.

On the European side a TG-43 dosimetry parameter database for brachytherapy sources is maintained by BRAPHYQS in close cooperation with the University of Valencia. The AAPM/IROC and BRAPHYQS databases are streamlined and continuously updated when consensus data is available.  

The consensus dosimetry parameters presented in both databases have been obtained from TG-43, TG-43U1, TG-43U1-Errata, TG-43U1S1, TG-43U1S1-Errata, TG-43U1S2, TG-43U1S2-Errata, and HEBD reports. The links below redirect to spreadsheets in MS excel format with the consensus datasets. In addition, QA tables in Cartesian coordinates have been added to each source consistent with the TG-43 datasets.

If you have questions or comments, please contact us.

Spreadsheets with dosimetry parameters:


Other non-official databases:

Low energy photon sources

The institutes offering calibration services for Europe for 125I and 103Pd seeds as of July 2019 can be found here.

High energy photon sources

Work in progress

Introduction of new model-based dose calculation algorithms (MBDCAs) capable of accounting for tissue and applicator heterogeneities in brachytherapy has been a major development in brachytherapy treatment planning in recent years. The AAPM TG-186 working group recommends commissioning MBDCA in routine clinical practice by exploring different clinical scenarios and evaluating them against Monte Carlo simulations and/or experiments. To facilitate this task in a clinical environment, the GEC-ESTRO, AAPM, and the ABG formed in 2011 the Working Group on dose calculation algorithms in brachytherapy (WGDCAB). This working group is linked to BRAPHYQS by several members being part of both groups. Together with the IROC-Houston Quality Assurance Center, a MBDCA Test Case Registry containing all the necessary data has been established.

  • Jose Perez-Calatayud, Facundo Ballester, Åsa Carlsson Tedgren, Alex Rijnders, Mark J. Rivard, Michael Andrássy, Yury Niatsetski, Thorsten Schneide, Frank-André Siebert.
    GEC-ESTRO ACROP recommendations on calibration and traceability of LE-LDR photon-emitting brachytherapy sources at the hospital level. Radiotherapy and Oncology 135 (2019) 120–129.
  • Peter Hoskin, Jack Venselaar, GEC ESTRO BRAPHYQS Group, GEC ESTRO PROBATE Group.
    Prostate brachytherapy in Europe: growth, practice and guidelines. Radiotherapy and Oncology 83 (2007) 1–2
  • Zourari K, Peppa V, Ballester F, Siebert FA, Papagiannis P (2014).  
    Brachytherapy structural shielding calculations using Monte Carlo generated, monoenergetic data. Med Phys (2012) 41 (2014), 043901; doi:10.1016/j.ejmp.2015.05.010
  • Murray L, Henry A, Hoskin P, Siebert FA, Venselaar J on behalf of the PROBATE group of the GEC ESTRO.  
    Second primary cancers after radiation for prostate cancer: A systematic review of the clinical data and impact of treatment technique. Radiother Oncol 110:213-28 (2014). doi:10.1016/j.radonc.2013.12.012
  • Pujades M del C, Granero D, Vijande J, Ballester F, Perez-Calatayud J, Papagiannis P, Siebert FA  
    Air-kerma evaluation at the maze entrance of HDR brachytherapy facilities. J. Radiol. Prot. 34 (2014) 741–753. 
  • Kirisits C, Rivard MJ, Baltas D, Ballester F, De Brabandere M, van der Laarse R, Niatsetski Y, Papagiannis P, Paulsen Hellebust T, Perez-Calatayud J, Tanderup K, Venselaar JLM, Siebert FA.
    Review of clinical brachytherapy uncertainties: Analysis guidelines of GEC-ESTRO and the AAPM. Radiother Oncol, (accepted for publication in 08.11.13) doi:10.1016/j.radonc.2013.11.00
  • Salembier C, Rijnders A, Henry A, Niehoff P, Siebert FA, Hoskin P.
    Prospective multi-center dosimetry study of low-dose Iodine-125 prostate brachytherapy performed after transurethral resection. Journal of Contemporary Brachytherapy 2013;5,2:63-6
  • Murray L, Henry A, Hoskin P, Siebert FA, Venselaar J on behalf of the BRAPHYQS/PROBATE group of the GEC ESTRO.
    Second primary cancers after radiation for prostate cancer: A review of data from planning studies.Radiation Oncology 2013, 8:172. The publication fee for this paper was sponsored by Varian Medical Systems doi:  10.1186/1748-717X-8-172
  • Hoskin PJ, Colombo A, Henry A, Niehoff P, Paulsen Hellebust T, Siebert FA, Kovacs G.
    GEC/ESTRO recommendations on high dose rate afterloading brachytherapy for localised prostate cancer: An update: Radiother Oncol (2013) 2013 Jul 19. S1538-4721(13)00298-5
  • De Brabandere M, Al-Qaisieh B, De Wever L, Haustermans K, Kirisits C, Moerland MA, Oyen R, Rijnders A, Van den Heuvel F, Siebert FA.  
    CT and MRI based seed localization in post-implant evaluation of permanent prostate brachytherapy. Brachytherapy 13 (2013) S1538-4721
  • Siebert, FA, Venselaar J, Hellebust-Paulsen T, Papagiannis P, Rijnders A, Kirisits C, Rivard M.  
    Dose-to-water calibration from the end-user perspective. Metrologia 49 (2012) S249–S252
  • Perez-Calatayud J, Ballester F, Das RK, DeWerd LA, Ibbott GS, Meigooni AS, Ouhib Z, Rivard MJ, Sloboda RS, Williamson JF.  
    Dose calculation for photon-emitting brachytherapy sources with average energy higher than 50 keV: Report of the AAPM and ESTRO. Med Phys 39 (2012) 2904-2929 report with consensus datasets
  • De Brabandere M, Haustermans K, Van den Heuvel F, Hoskin P, Siebert FA.  
    Prostate post-implant dosimetry: interobserver variability in seed localization, contouring, and fusion. Radiother Oncol 104 (2012) 192–198
  • DeWerd LA, Ibbott GS, Meigooni AS, Mitch MG, Rivard MJ, Stump KE, Thomadsen BR, Venselaar JLM. 
    A dosimetric uncertainty analysis for photon-emitting brachytherapy sources: Report of AAPM Task Group No. 138 and GEC-ESTRO. Med Phys38 (2011) 782-801
  • Papagiannis P, Baltas D, Granero D, Pérez-Calatayud J, Gimeno J, Ballester F, Venselaar JLM.  
    Radiation transmission data for radionuclides and materials relevant to brachytherapy facility shielding. Med Phys 35 (2008) 4898-4906
  • Siebert FA, De Brabandere M, Kirisits C, Kovács G, Venselaar J.  
    Phantom Investigations on CT Seed Imaging for Interstitial Brachytherapy. Radiother Oncol 85 (2007) 316-323
  • Roué A, Venselaar JLM, Ferreira IH, Bridier A, Van Dam J.  
    Development of a TLD mailed system for remote dosimetry audit for 192Ir HDR and PDR sources. Radiother Oncol 83 (2007) 86-93
  • Kirisits C, Siebert FA, Baltas D, De Brabandere D, Paulsen Hellebust T, Berger D, Venselaar J.  
    Accuracy of volume and DVH parameters determined with different brachytherapy treatment planning systems. Radiother Oncol 84 (2007) 290-297
  • Roué A, Ferreira IH, Van Dam J, Svensson H, Venselaar JLM.  
    The EQUAL-ESTRO audit on geometric reconstruction techniques in brachytherapy. Radiother Oncol 78 (2006) 78-83

BRAPHYQS is supported by ESTRO and receives sponsorship from industry for its meetings.

The following companies support the BRAPHYQS working group regularly:

 Eckert & Ziegler Bebig GmbH


Nucletron, an Elekta company


Varian Medical Systems

BRAPHYQS consists of a core group of physics experts in brachytherapy. Depending on the running working package topics external experts are invited to participate in specific projects. Therefore, the list of participants changes from time to time (Including the TG43 members and consultants).

For an up-to-date list of the BRAPHYQS core group please contact the group co-ordinator: Frank-André Siebert

Frank-André Siebert, DE (Chair)

Dimos Baltas, DE

Marisol De Brabandere, BE

Taran Hellebust, NO

Christian Kirisits, AT

Panagiotis Papagiannis, GR

José Pérez-Calatayud, ES

Alex Rijnders, BE

Mark Rivard, USA

Kari Tanderup, DK

Åsa Carlsson Tedgren, S 

Frank Verhaegen, NL

            Javier Vijande, ES

            Jacob Johansen, DK