الفهرس 
General IntroductionOnly 14 pages are availabe for public view
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Abstract
This study has carried out on some physical properties of photon beams with nominal energies 6 and 10 MV, which produced by the medical linear accelerator that existed in the Minia Oncology Center, Ministry of Health and population, and used for the cancer patients radiotherapy. This study has dealt with the errors estimation that can be occurred in the assessment of the radiotherapeutic dose for the patients which may arise from the linear accelerator, such as the isocenter of the mechanical movements and its coincidence with the light and radiation fields.
Also, the errors that resulted from the geometry of the radiation beam virtual source focus and the way to measure its energy.
In addition, there are errors produced from the dosimetry tools that available in our center when used in the linear accelerator calibration and radiation dosimetry. And was observed from the results that these errors can give a wrong estimation in the radiotherapeutic dose calculation, where these errors are classified as systematic and random errors.
In general, the results pointed to the importance of the correcting these errors and take into account the correction factors which concluded from the various physical situations that have been studied in this thesis when calculating the radiotherapeutic dose. The purpose from that is to reduce the value of the uncertainty factor of the radiotherapeutic dose according to the recommendations of all international dosimetry protocols.
This study has defined recommendations that it can be used in the increase of the radiotherapeutic dose calculation accuracy for the cancer patients via applying this study as a quality assurance protocol for the radiotherapeutic dose given for the patients.