The effects of correction factors to treatment doses in radiation treatment

The purpose of this study is to determine whether there is an effect and the effect on the rate of the changes of the factors affecting the dose to dose rate of output rate. The measurements were performed in water-equivalent solid phantoms by the using NE Technology brand 2570/1 model electrometer, 0,6 cc farmer type ion chamber and 6, 15, 25 MV photon beams which was obtained in GE brand Saturne 43 linear accelerator in Radiation Onvology Clinic of Dr. Abdurrahman Yurtaslan Oncology Education and Research Hospital when changing environmental conditions such as temperature, preasure at different times. For each energy, efficiency of dose was measured by using four different ion chambers and the factors affecting the efficiency of dose are calculated according to the criteria of TRS No 277. The percentage of the statistical and mathematical error of the factors affecting the dose were detected and determined the contributions of dose. From this study, the following conclusions have been reached : Perturbation and calibration factors change are reflected in the dose at the same rate; dose significantly affected by pressure changes; although a relatively small effect from the changes of the parameters of temperature, polarity and recombination correction factors , the changes of stopping powers of water to air have a negligible effect compared to other parameters.Key Words : Radiation oncology, x-ray treatment, linear accelerator, absorbed dose, correction factor, TRS-277, output dose