Experimental determination of the Task Group-43 dosimetric parameters of the new I25.S17plus 125I brachytherapy source



      To present experimental dosimetry results for the new IsoSeed I25.S17plus 125I brachytherapy source, in fulfillment of the American Association of Physicists in Medicine recommendation for, at least one, experimental dosimetry characterization of new low-energy seeds before their clinical implementation.

      Methods and Materials

      A batch of 100 LiF thermoluminescent dosimeter (TLD)-100 microcubes was used for the experimental determination of the dose-rate constant, radial dose, and anisotropy functions, in irradiations performed using two Solid Water phantoms. Monte Carlo (MC) simulations were used to determine appropriate correction factors that account for the use of Solid Water as a phantom material instead of liquid water and for the different energy response of the TLD dosimeters in the experimental 125I photon energies relative to the 6 MV x-ray photon beam used for the TLD calibration. Measurements were performed for four I25.S17plus seeds; one with direct traceability of air-kerma strength calibration to National Institute of Standards and Technology and three with secondary National Institute of Standards and Technology traceability.


      A mean dose-rate constant, Λ, of 0.956 ± 0.043 cGy h−1 U−1 was experimentally determined for the I25.S17plus source, which agrees within uncertainties with the MC result of 0.925 ± 0.013 cGy h−1 U−1 calculated independently for the same seed model in a previous study. Agreement was also observed between the measured and the MC-calculated radial dose and anisotropy function values.


      Experimental dosimetry results for the I25.S17plus 125I source verify corresponding independent MC results in the form of Task Group-43 dosimetry parameters. The latter are found in agreement within uncertainties with sources of similar design incorporating a silver marker, such as the Oncura OncoSeed Model 6711.


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        • Hedtjärn H.
        • Carlsson G.A.
        • Williamson J.F.
        Monte Carlo-aided dosimetry of the Symmetra model I25.S06 125I, interstitial brachytherapy seed.
        Med Phys. 2000; 27: 1076-1085
        • Patel N.S.
        • Chiu-Tsao S.-T.
        • Williamson J.F.
        • et al.
        Thermoluminescent dosimetry of the SymmetraTM 125I model I25.S06 interstitial brachytherapy seed.
        Med Phys. 2001; 28: 1761-1769
        • Lymperopoulou G.
        • Papagiannis P.
        • Sakelliou L.
        • et al.
        Monte Carlo and thermoluminescence dosimetry of the new IsoSeed model I25.S17 125I interstitial brachytherapy seed.
        Med Phys. 2005; 32: 3313-3317
        • Rivard M.J.
        • Coursey B.M.
        • DeWerd L.A.
        • et al.
        Update of AAPM Task Group No. 43 Report: A revised AAPM protocol for brachytherapy dose calculations.
        Med Phys. 2004; 31: 633-673
        • Pantelis E.
        • Papagiannis P.
        • Anagnostopoulos G.
        • et al.
        New 125I brachytherapy source IsoSeed I25.S17plus: Monte Carlo dosimetry simulation and comparison to sources of similar design.
        J Contemp Brachytherapy. 2013; 5: 240-249
        • Constantinou C.
        A solid water phantom material for radiotherapy x-ray and γ-ray beam calibrations.
        Med Phys. 1982; 9: 436-441
        • Williamson J.F.
        • Coursey B.M.
        • DeWerd L.A.
        • et al.
        Guidance to users of Nycomed Amersham and North American Scientific, Inc., I-125 interstitial sources: Dosimetry and calibration changes: Recommendations of the American Association of Physicists in Medicine Radiation Therapy Committee Ad Hoc Subcommittee.
        Med Phys. 1999; 26: 570-573
        • Anagnostopoulos G.
        • Baltas D.
        • Karaiskos P.
        • et al.
        Thermoluminescent dosimetry of the selectSeed 125I interstitial brachytherapy seed.
        Med Phys. 2002; 29: 709-716
        • Meigooni A.S.
        Instrumentation and dosimeter-size artifacts in quantitative thermoluminescence dosimetry of low-dose fields.
        Med Phys. 1995; 22: 555-561
        • Kennedy R.M.
        • Davis S.D.
        • Micka J.A.
        • et al.
        Experimental and Monte Carlo determination of the TG-43 dosimetric parameters for the model 9011 THINSeedTM brachytherapy source.
        Med Phys. 2010; 37: 1681-1688
        • Luxton G.
        Comparison of radiation dosimetry in water and in solid phantom materials for I-125 and Pd-103 brachytherapy sources: EGS4 Monte Carlo study.
        Med Phys. 1999; 21: 631-641
        • Rogers D.W.O.
        General characteristics of radiation dosimeters and a terminology to describe them.
        in: Rogers D.W.O. Cygler J.E. Clinical dosimetry measurements in radiotherapy. Medical Physics Publishing, Madison, WI2009: 137-145
        • Nath R.
        • Anderson L.L.
        • Luxton G.
        • et al.
        Dosimetry of interstitial brachytherapy sources: Recommendations of the AAPM Radiation Therapy Committee Tasks Group No. 43.
        Med Phys. 1995; 22: 209-234
      1. Goorly T, James M, Booth T, et al. Initial MCNP6 Release Overview—MCNP6 version 1.0. Available at: Accessed May 9, 2014.

        • Hubbell J.H.
        • Seltzer S.M.
        Tables of x-ray mass attenuation coefficients and mass energy absoprtion coefficients (version 1.4).
        National Institute of Standards and Technology, Gaithersburg, MD2004 ([Online] Available at:) (Accessed 30-Mar-2014)
        • Sheikh-Bagheri D.
        • Rogers D.W.O.
        Monte Carlo calculation of nine megavoltage photon beam spectra using the BEAM code.
        Med Phys. 2002; 29: 391-402
        • Rasmussen B.
        • Davis S.
        • Micka J.
        • et al.
        SU-GG-T-292: The response of LiF:Mg,Ti thermoluminescent dosimeters to low-energy photons.
        Med Phys. 2008; 35: 2792
        • Hranitzky C.
        • Stadtmann H.
        • Olko P.
        Determination of LiF:Mg,Ti and LiF:Mg,Cu,P TL efficiency for X-rays and their application to Monte Carlo simulations of dosemeter response.
        Radiat Prot Dosimetry. 2006; 119: 483-486
        • Nunn A.A.
        • Davis S.D.
        • Micka J.A.
        • et al.
        LiF:Mg,Ti TLD response as a function of photon energy for moderately filtered x-ray spectra in the range of 20–250 kVp relative to 60Co.
        Med Phys. 2008; 35: 1859-1869
        • Davis S.D.
        • Ross C.K.
        • Mobit P.N.
        • et al.
        The response of lif thermoluminescence dosemeters to photon beams in the energy range from 30 kV x rays to 60Co gamma rays.
        Radiat Prot Dosimetry. 2003; 106: 33-43
        • Tedgren A.C.
        • Hedman A.
        • Grindborg J.E.
        • et al.
        Response of LiF:Mg,Ti thermoluminescent dosimeters at photon energies relevant to the dosimetry of brachytherapy (<1 MeV).
        Med Phys. 2011; 38: 5539-5550
        • Andreo P.
        • Burns D.T.
        • Hohlfeld K.
        • et al.
        Absorbed dose determination in external beam radiotherapy.
        International Atomic Energy Agency (IAEA), Vienna, Austria2000 (Technical Report Series No. 398)
        • Meigooni A.S.
        • Awan S.B.
        • Thompson N.S.
        • et al.
        Updated Solid WaterTM to water conversion factors for 125I and 103Pd brachytherapy sources.
        Med Phys. 2006; 33: 3988-3992
        • Williamson J.F.
        Comparison of measured and calculated dose rates in water near I-125 and Ir-192 seeds.
        Med Phys. 1991; 18: 776-786
        • Andreo P.
        • Burns D.T.
        • Salvat F.
        On the uncertainties of photon mass energy-absorption coefficients and their ratios for radiation dosimetry.
        Phys Med Biol. 2012; 57: 2117-2136
        • Chen Z.
        • Bongiorni P.
        • Nath R.
        Experimental characterization of the dosimetric properties of a newly designed I-Seed model AgX100 125I interstitial brachytherapy source.
        Brachytherapy. 2012; 11: 476-482
        • Tailor R.
        • Tolani N.
        • Ibbott G.S.
        Thermoluminescence dosimetry measurements of brachytherapy sources in liquid water.
        Med Phys. 2008; 35: 4063-4069
        • Papagiannis P.
        • Sakelliou L.
        • Anagnostopoulos G.
        • et al.
        On the dose rate constant of the selectSeed 125I interstitial brachytherapy seed.
        Med Phys. 2006; 33: 1522-1523
        • Popescu C.C.
        • Wise J.
        • Sowards K.
        • et al.
        Dosimetric characteristics of the Pharma SeedTM model BT-125-I source.
        Med Phys. 2000; 27: 2174-2181
        • Dolan J.
        • Li Z.
        • Williamson J.F.
        Monte Carlo and experimental dosimetry of an 125I brachytherapy seed.
        Med Phys. 2006; 33: 4675-4684