If the radiation given to patients can’t measure precise, the results that can’t repair may occur.
The purpose of study is to compare percent depth dose (PDD) for PMMA, polystyrene, blood liquid, soft tissue and water using EGSnrc that utilized for Monte Carlo simulation.
BEAMnrc and DOSXYZnrc were utilized to model linac head and measure respectively. Firstly, Linac head geometry was simulated using BEAMnrc. Secondly, phantom doses were measured in DOSXYZnrc for various materials.
When the values examine, it seems that absorptions of blood liquid, soft tissue and water are similar at high photon energy.
We could see that PMMA did not correspond well with other materials. Because density of PMMA is much than other densities, this mismatch can be attributed to density of PMMA.
We have obtained a large gamma index value for PMMA. It was concluded that the PMMA was not good materials equivalence of water. PMMA showed the same properties from surface to maximum dose depth then the difference began to increase throughout the depth.
It was seen that the materials having close density value with each other had almost same PDD. The results have indicated that the water and polystyrene was convenient materials instead of soft tissue and blood liquid. All solid phantoms that are claimed to be equivalent to water should be similarly checked before being used for dosimetry measurements. Still in certain periods, the results obtained from different material must compare with results on water phantom for definite dose distribution on patient.
Anahtar Kelimeler: PMMA, polystyrene, soft tissue, BEAMnrc, XCOM
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