The Journal of Korean Society for Radiation Therapy (대한방사선치료학회지)
- Volume 8 Issue 1
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- Pages.75-81
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- 1996
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- 1598-8449(pISSN)
The Measurement of Dose Distribution in the Presence of Air Cavity and Underdosing Effect Result from Lack of Electronic Equilibrium
조사면내 공동의 존재에 따른 선량분포의 변화측정
- Jo, Jeong-Hui (Dept. Radiation Oncology, Yonsei University College of Medicine) ;
- Bang, Dong-Wan (Dept. Radiation Oncology, Yonsei University College of Medicine) ;
- Park, Jae-Il (Dept. Radiation Oncology, Yonsei University College of Medicine)
- Published : 1996.11.01
Abstract
When high energy photon beam is incident upon an air cavity interface the effect of ionization build-up observed . This phenomenon is resulting from the surface layers of the lesions are significant deficiency of electrons reaching the layers because of the replacement, of solid scattering material by the air cavity, that is lack of electronic equilibrium. Measurement have been made in an acrylic phantom with a parallel plate chamber and high energy photon beams, CO-60, 4MV, 6MV and 10MV X-rays have been investigated. The result of our study show that a significant effect was measured and was determined to be very dependent on field size, air cavity dimension and photon energy. The reductions were much larger for 10MV beam, underdosage at the interface was 12, 12.2, 16.9 and