In the present work, Monte Carlo code MCNPX was used to determine the cellular dosimetric parameter; cellular S-values for frequently used radionuclides in targeted radionuclide therapy including 32 P, 89 Sr, 90 Y, 117m Sn, 153 Sm, 166 Ho, 170 Tm, 177 Lu, 186 Re and 188 Re. We considered the effect of some factors such as cell size, radiation subcellular localization and chemical composition on cellular S-values. The cells were defined as two concentric spheres and the radionuclides were assumed to be uniformly distributed in one of the cell compartments including cell surface (CS), cytoplasm (Cy), and nucleus (N). A comparison between MCNPX results with obtained MIRDcell values was performed. Deviations between MCNPX and MIRDcell were found to be less than ∼15% for selfabsorption, in the cases of S(C←C) and S(N←N) values whereas discrepancies in S-values increased up to ∼22% for C←CS and ∼28% for N←Cy and N←CS. The results showed a significant change with increasing the cell and cell nucleus size. For a given radionuclide, with increasing radii, S-values decreased in all compartments. For a given radius of the cell and nucleus, low energy radionuclides had higher S-values. For all source-target combinations, 153 Sm and 90 Y had the highest and lowest S-values, respectively.

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The conversion of ion beam energy into thermal X-ray radiation by means of stretched cylindrical volumes is discussed. Converting the kinetic energy of heavy ion beam into radiation energy at high efficiency is important for heavy ion fusion. The conversion efficiency between different materials, low-Z and high-Z material, is compared and simulations have been performed by SRIM code. Our results show high-z materials are superior converters. It is found to achieve a high conversion efficiency, a deposition power higher than 10 16 W/cm 2 is required.