Relative radiotherapic thyroid dose evaluation for different gamma sources and explication of calculation for back scattering factor

In this study, In this study, different phantom materials are utilized to simulate the neck of human body which is used to irradiate the thyroids of human body by Co-60 and Cs-137 gamma radioactive sources. All results on this study is the same narrow-beam geometry. Absorbed dose notion and gamma measurement results are evaluated as part of thyroid dose. The experiments are done four different phantom materials and the results showed that the most thick phantom which is the man have the highest absorbed dose within the scope of relative absorbed dose calculations. It is reached that the absorbed dose is the lowest in the experiments of child neck phantom. In the all studies of ( Co-60 and Cs-137 ) radioactive sources is concluded that the all three phantom materials have the highest absorbed dose respectively water, edging strip, paraffine and cadaver. When this results are compared with density of phantom materials, it is attained that the most intensive material have the highest absorbed dose. The calculations within the scope of child, woman and man simulations is also done for water, paraffine, edging strip and cadaver in regard to Back scattering factor ( BSF) and it is observed that BSF is related to diameter of neck.