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Transmission Dose Measurement of Gamma-ray Using Tungsten Shield

텅스텐 차폐체의 감마선 투과선량 측정

  • Received : 2018.05.29
  • Accepted : 2018.09.07
  • Published : 2018.09.30

Abstract

This study was conducted to investigate the penetration dose and shielding rates of tungsten shields used in apron material by changing the type of source used in the nuclear medicine department, thickness of shielding material and distance between the source and detector. For the experiment, the source, shield, and detector were arranged in a straight line and measured with an inspector at a height of 100 cm. The highest shielding effect of tungsten was measured for $^{201}Tl$, while $^{123}I$ showed a higher shielding effect than $^{99m}Tc$. For the sources used in the experiment, the penetration dose decreased with distance and the shielding rate was measured with thicker thickness. However, the shielding rate of $^{13}1I$ and $^{18}F$ sources was found to be lower than when there was no shielding at 0.25 mmPb shield. Therefore, even if the radiation shielding effect of tungsten is high, considering the characteristics according to the type of source and the thickness of the shielding material, it may be helpful to reduce the exposure.

본 연구는 Apron의 재질로 이용되고 있는 텅스텐 차폐체를 핵의학과에서 사용하는 선원의 종류와 차폐체의 두께, 선원부터 검출기 사이의 거리를 변화시켜 차폐체에 투과시킨 후 투과선량과 차폐율을 알아보고자 하였다. 실험을 위해서 선원과 차폐체와 검출기를 일직선으로 배치하고 높이 100 cm 지점에서 Inspector로 측정하였다. 그 결과 텅스텐에 차폐효과가 가장 높은 선원은 $^{201}Tl$ 선원으로 측정되었고, $^{123}I$ 선원이 $^{99m}Tc$ 선원보다 차폐효과가 높게 나타났다. 실험에 사용한 선원과 검출기 사이의 거리는 멀어질수록 투과선량은 작아졌고, 텅스텐 차폐체의 두께는 두꺼울수록 차폐율은 높게 측정되었다. 하지만 $^{131}I$$^{18}F$ 선원에서는 0.25 mmPb의 차폐체를 사용했을 경우 차폐체가 없을 경우 보다 차폐율이 감소하는 것을 확인하였다. 따라서 $^{13}1I$$^{18}F$ 선원을 사용할 경우에는 방사선 차폐효과가 높은 텅스텐일지라도 선원의 종류에 따른 특성과 차폐체의 두께를 고려하여 사용하길 권장하고, 실험 결과를 참고하여 사용한다면 피폭 저 감화방안에 도움을 줄 수 있을 것으로 생각된다.

Keywords

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