Study the Factors Affecting the Quality Assurance of Superficial RadiotherapyX-RayMachine

The aim of this study was to analyze factors influencing the quality assurance of superficial radiotherapy X-ray machine such as dose output reproducibility, linearity, kV accuracy, time accuracy. Moreover the entrance skin dose for hand, face and nose using Perspex phantom was measured. We measured these factors and entrance skin doses using Unidose master connected with 0.2 cc soft X-Ray Chamber type 23342, which was placed above a Perspex phantom inside the chosen field size of used applicator on the couch. The reproducibility of dose output was 0.17 %, the kilo voltage accuracy percentage and time accuracy percentage were ranged from.38 to 0.87 % and -0.96 to 3.4 % respectively. Linearity of radiotherapy X-ray machine was 0.02 which lower than the tolerance limit of the American Association of physicist in Medicine reference value, the limit specified in the academic literature and international publications. The relative error for entrance skin dose equals 3 %. The entrance skin doses for face, nose and hand were 56.68 0.307, 241.2 2.15 and 60.52 0.104 mGy respectively. The tests for the quality assurance of superficial radiotherapy X-ray machine was compared and assessed with the international tolerance.