Journal of Radiation Protection and Research

The Korean Association for Radiation Protection (대한방사선방어학회)
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Characteristics of Dose Distribution at Junctional Area Using the Divergency Cutout Block in the Abutted Field of Photon and Electron Beams

광자선과 전자선의 인접조사에서 선속 퍼짐현상이 고려된 전자선 차폐물을 이용한 접합 조사면의 선량분포 특성

  • Im, In-Chul (Department of Radiological Science, Dongeui University) ;
  • Lee, Jae-Seung (Department of Radiation Oncology, Good Samaritan Hospital)
  • 임인철 (동의대학교 방사선학과) ;
  • 이재승 (선린의료원 방사선종양학과)
  • Received : 2011.08.05
  • Accepted : 2011.08.23
  • Published : 2011.09.30
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Abstract

This study investigated characteristics of dose distribution at junction field of X-ray and electron beams according to the method for fabricating the insert block on the electron cone. Insert block were fabricated to the divergency cutout block and the straight cutout block. For the 6 MV X-ray and 10 MeV nominal energy of electron beam, we was adjacent to the light field of X-ray and electron beam at a surface of matrix chamber and measured to beam profile of abutted field in the 0, 1, 2, 3 cm measurement depth. As a result, characteristics of dose distribution at junction field, straight block was existent that over dose area exceed the give dose more than 5% and under dose area with a rapid change in dose distribution. However, divergency block had remarkably decreased the over dose area caused by the lateral scattering effects of decrease, and being existed uniformity dose distribution in the junction field. Therefore, divergency block were the benefits of radiation dose delivery, in order to applied the clinical, measurement of electron beams according to the fabrication method of the block should be considered carefully.

본 연구는 조사통(electron cone)에 삽입되는 전자선 차폐물의 제작방법에 따른 X-선과 전자선의 인접 조사면의 선량분포 특성을 알아보고자 하였다. 차폐물의 제작은 전자선속 퍼짐현상을 고려한 차폐물(divergency block)과 고려하지 않은 차폐물(straight block)을 구분하여 제작하였다. 6 MV X-선과 10 MeV 전자선을 대상으로 표면에서 X-선과 전자선의 조사면을 인접시키고 측정 깊이 0, 1, 2, 3 cm에서 빔 측면도(beam profile)를 측정하였다. 측정 결과 인접 조사면의 선량분포는 straight block의 경우, 기준 투여선량의 5%를 초과하는 고선량 영역과 인접 조사면에서 급격한 선량분포를 형성하였으나 divergency block의 경우, 측방산란효과가 감소함으로서 고선량 영역이 현저하게 감소하였으며 인접 조사면에서 균일한 선량분포를 보였다. 따라서 전자선속 퍼짐을 고려한 경우 선량학적 이점을 제공하였고 이를 임상에 적용하기 위하여 전자선의 차폐물 제작방법에 따른 선량측정을 신중하게 고려해야 할 것이다.

Keywords

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