6MV 광자선에서 공동에 의한 조직 선량변동에 관한 연구

The Study of Tissue Dose Perturbation by Air Cavity with 6MV Photon Beam

Purpose : To determine the perturbation effect in the tissue downstream from surface layers of lesions located in the air/tumor-tissue interface of larynx using 6MV photon beam. Materials and Methods : Thermoluminescent dosimeters(TLDs). were embedded at 3 measurement location in slab no.7 of a humanoid phantom and exposed to forward and backward direction using various field sizes(4X4cm²-15X15cm²). Results : At the air/tissue interface forward dose perturbation factor(FDPF) is about 1.085 with 4X4cm², 1.05 with 7X7cm², 1.048 with 10X10cm² and 0.99 with 4X4cm², 0.981 with 7X7cm², 0.956 with 10X10cm² and 0.97 with 15X15cm². Conclusion : FDPF is greater as field size is smaller. And FDPF is smaller as the distance is further from the air/tissue interface.