Radiation Oncology Journal
- 제9권2호
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- Pages.333-336
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- 1991
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- 2234-1900(pISSN)
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- 2234-3156(eISSN)
6MV 방사선의 물리학적 Penumbra
The Physical Penumbra of the 6MV X-ray
- Cho Moon-June (Department of Radiology, College of Medicine and Cancer Research Institute, Chungnam National University) ;
- Kang Wee-Saing (Department of Therapeutic Radiology, College of Medicine, Seoul National University)
- 발행 : 1991.12.01
초록
충남대학교병원 치료방사선과내 설치되어 있는 6MV선형가속기를 이용하여 음영을 측정하여 다음과 같은 결과를 얻었다. 1) 조사면 크기가 커질수록 음영폭은 중가하였으며 10x10 Cm 이상의 조사면에서는 계산한 음영폭보다 측정치가 대개 크게 나타났다. 조사면이 커질수록 이 차이는 더욱 증가하였다. 2) 깊이가 증가하면 음영폭도 증가하였다. 3)
High energy Photon beam has a sharp beam margin due to a less side scatter and the other things. But there still remains a penumbra where the dose changes rapidly in the region near the edge of a radiation beam, although it is short in width. It is suggested that the width of the penumbra depends on the source size, distance from source to diaphragm, source to skin distance, and depth in tissue. However, it is also supposed that the other factors influence the penumbra width. In this paper, we investigate changes of the physical penumbra widths according to various field sizes and depths, by using the three dimensional dosimetry system. As a result, we found that as field size and depth increase, the physical penumbra width also increases.