RESUMO
PURPOSE: This study was performed for adequate irradating tumor area when 6 MV linear accerelator photon was used to treat the head and neck tumor. The skin surface dose and maximum build-up ragion was measured by using a spoiler which was located between skin surface and collimator. METHODS: A spoiler was made of tissue equivalent materials and the skin surface dose and maximum build-up region was measured varing with field size, thickness of spoiler and interval between skin and collimator. The results of skin surface dose and maximum build-up dose was represented as a build-up ratio and it was compared with dose distribution by using a bolus. RESULTS: The skin surface dose was increased with appling spoiler and decreased by distance of the skin-spoiler separation. The maxium build-up region was 1.5 cm below the skin surface and it was markedly decreased near the skin surface. By using a 1.0-cm thickness spoiler, Dmax moved to 5, 10.2, 12.3, 13.9 and 14.8 mm from the skin surface by separation of the spoiler from the skin 0, 5, 10, 15, 20 cm, respectively. CONCLUSION: The skin surface dose was increased and maximum build-up region was moved to the surface by using a spoiler. Therefore spoiler was useful in treating by high energy photon in the head and neck tumor.