176 Toossi MTB et al. / GZP6-TG43 A B C FIGURE 4. Anisotropy functions of GZP6 60Co (number 3), Ralstron (type 2) 60Co (by Papagiannis et al.4) and microSelec- tron 192Ir (by Karaiskos et al.16) sources: (A) for r=2 cm; (B) for r=5 cm; (C) for r=10 cm. The parameters of the fitted polynomial are as follows: a5=1.00010-6, a4=-5.00010-5, a3=0.0007, a2=-0.0039, a1=-0.01, a0=1.0087. A graphical representation of g(r) values for the GZP6 source is presented in Figure 3 and com- Radiol Oncol 2012; 46(2): 170-178. pared with the corresponding data for the Ralstron (type 2) 60Co source reported by Papagiannis et al.4 and microSelectron 192Ir source reported by Karaiskos et al..16 Table 6 presents the anisotropy function data for GZP6 60Co source number 3. F(r, θ) values of the GZP6, Ralstron and microSelectron sources for dis- tances of 2, 5 and 10 cm are presented in Figure 4 A-C. FIGURE 3. Radial dose function versus radial distance from the source for GZP6 60Co (number 3), Ralstron (type 2) 60Co (by Papagiannis et al.4) and microSelectron 192Ir (by Karaiskos et al.16) sources. TABLE 5. Monte Carlo calculated radial dose functions of GZP6 source number 3 Radial distance r (cm) 4.5 1 1.5 2 2.5 3.5 3 4 5 6 7 8 9 10 12 13 15 20 gL (r) 1.000 0.983 0.976 0.968 0.959 0.950 0.943 0.932 0.921 0.909 0.890 0.876 0.851 0.831 0.785 0.767 0.679 0.539