Abstract. 

Calculation of dosimetry parameters by TG-60 approach for beta sources and TG-43 approach for gamma sources can help to design brachytherapy sources.  In this work, TG-60 dosimetry parameters are calculated for the Sm-153 brachytherapy seed using the Monte Carlo simulation approach.  The continuous beta spectrum of Sm-153 and probability density are applied to simulate the Sm-153 source.  Sm-153 is produced by neutron capture during the 152Sm(n,\( \gamma\))153Sm reaction in reactors.  The Sm-153 radionuclide decays by beta rays followed by gamma-ray emissions with half-life of 1.928 days.  Sm-153 source is simulated in a spherical water phantom to calculate the deposited energy and geometry function in the intended points.  The Sm-153 seed consists of 20% samarium, 30% calcium and 50% silicon, in cylindrical shape with density 1.76gr/cm^3.  The anisotropy function and radial dose function were calculated at 0-4mm radial distances relative to the seed center and polar angles of 0-90 degrees.  The results of this research are compared with the results of Taghdiri et al. ( Iran.  J. Radiat.  Res.  9, 103 (2011)).  The final beta spectrum of Sm-153 is not considered in their work.  Results show significant relative differences even up to 5 times for anisotropy functions at 0.6, 1 and 2mm distances and some angles.  MCNP4C Monte Carlo code is applied in both in the present paper and in the above-mentioned one.