Application of MCNP4C in Ru-106 eye plaques dosimetry and its compared with Experimental method

Bckground and There are a number of radioactive sources for brachytherapy in various shapes and sizes. Ru- 106 (Ruthenium، 106) ophthalmic plaque have been used for many years in treatment of uveal melanoma. The plaques consist of a thin film of 106 Ru، a β emitter encapsulated in pure silver. The principle purpose of the present work was to evaluate dose distribution along central axis and two sides axis of eyes plaques. Calibration of eye plaques was performed with use of Monte Carlo code (MCNP4C) and experimental measurement. The absolute dose was measured at centre and two sides axis of the Ru-106 eye applicators a (PMMA) spherical phantom with a radius of 12mm and height of 28 mm was constructed. To verify experimental measurements، simulation with applicators، TLD and eye phantom was utilized using MCNP4C code a P41. 8GHZ personal computer. The run time of MCNP4C for each eye plaque was 4200 min and the * f8 tally and cut off of energy was used. Simulated and practical dose distribution of six different types of eye plaques CCA، CCB، CGD، CCY، COB and CIA in the eye phantom were studied. The absolute and relative depth dose along the symmetry axis and two sides axes of the applicators were also evaluated from the surface to about 9 mm distance with less statistical uncertainty than that proposed by NIST and Bebig. The results are fully well comparable to producers proposed data as shown in the curves and graphs. Precision Monte Carlo comparison of the dose distributions applicators listed and absolute dose distribution of practical method show that these plaques were useful to treat uveal melanoma using Monte Carlo method in radiotherapy.