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Showing 2 results for 137cs
M.b. Tavakoli, D. Shahbazi-Gahrouei, M. Hosseinpour,
Volume 5, Issue 3 (12-2007)
Abstract
Background: For an effective treatment planning in brachytherapy, it is necessary to know the accurate source dosimetric information such as air kerma strength, exposure rate constant, dose rate constant and redial dose distribution. The usual method to determine these factors is thermo luminescent dosimeter (TLD) dosimetry. Nowadays, another more accurate method is known to be the Monte Carlo simulation, and it is widely used in determining of brachytherapy sources dosimetric factors. The aim of the present study has been determine to dose distribution of 137Cs sources configuration used in interacavitary low dose rate (LDR) Selectron brachytherapy by Monte Carlo simulation method. Materials and Methods: Simulation has been performed for 137Cs stainless-steel encapsulated source in 2.5 mm in diameter of Selectron system. Six different combinations of 137Cs sources were simulated and each combination was put into different applicator. The Monte Carlo MCNP4C code was used for simulation. The number of history was taken 1 million for the calculation of air kerma strength and exposure rate constant and 0.1 million for calculating dose rate constant and redials dose distribution. Results: Maximum air kerma strength was obtained for the combination with fourteen active sources and found to be 919.3 |µ|Gym2h-1 while its minimum value was 133.9 µ|Gym2h-1 for the case with two active sources. Maximum and minimum dose rate constant of 4.3 cGyh-1mCi-1 and 2.1 cGyh-1mCi-1 were obtained for the combination with eight and fourteen active sources, respectively. Conclusion: The results indicated that the Monte Carlo simulation method may be useful to determine dosimetric characteristics of brachytherapy sources.
Dr. V. Changizi, Z. Jafarpoor, M. Naseri,
Volume 8, Issue 2 (9-2010)
Abstract
Background: The sources of radioactivity in the
environment have natural, terrestrial and extraterrestrial,
and anthropogenic origins. Plants may get radioactive
nuclides in two ways: (i) by the deposition of
radioactive fallout, (ii) by absorption from the soil.
Materials and Methods: The Concentrations of the
natural radionuclides (226Ra, 228Ra, 40K) and the
artificial radionuclide (137Cs) in leek and parsley in
Tehran province-Iran were determined using HPGe.
Also the effective dose due to the ingestion of such
vegetables by the population of Tehran province was
studied. Results: The average value of radionuclide
concentrations in parsley samples were measured
177.69 ± 12.47 mBq kg-1 fresh for 226Ra 349.62 ±
28.42 mBq kg-1 fresh for 228Ra 187364.6 mBq kg-1 fresh
for 40K. The average value of radionuclide concentrations
in leek samples were measured 94.31 ± 6.46
mBq kg-1 fresh for 226Ra 207.47 ± 19.46 mBq kg-1 fresh
for 228Ra 174555 ± 1704.21 mBq kg-1 fresh for 40K.
The concentrations of 137Cs in most of Parsley and
Leek samples were below the minimum detectable
activity (MDA). Conclusion: The Average 226Ra and
228Ra activities in 29 leek and parsley samples were
about 2.63 and 6.78 times the reference values,
respectively. The annual effective dose resulting from
the studied radionuclides for the adult population in
Tehran province were found to be safe in comparison
with normal background areas. Iran. J. Radiat. Res.,
2010 8 (2): 103-110
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