178 Toossi MTB et al. / GZP6-TG43 Dose distributions from the superimposition method The dose distributions for the GZP6 source No. 1, 2 and 5 which was obtained by MC simulations of the sources and the superimposition method de- scribed are presented in the Figure 5. The dose con- tours of 1, 2, 5, 10, 15 and 20 Gy were plotted. As it can be observed the dose distributions obtained by the two methods for the sources 1, 2 and 5 are equal. The superimposition algorithm developed in this study is able to produce dose distributions for the GZP6 sources No. 1, 2 and 5 from the dose dis- tribution of the source No. 3. The algorithm is also applicable for other bracytherapy units in which an arrangement of sources is used in the treatment process. These results may provide comprehen- sive dosimetric information that could be clinically more applicable for dose calculations around dif- ferent implants by superimposition method. 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