Journal of radiological science and technology (대한방사선기술학회지:방사선기술과학)

Korean Society of Radiological Science (대한방사선과학회)
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Comparison of Horizontal and Vertical Noise Power Spectrum in Measurements by Using Various Electronic Portal Imaging Devices in Radiation Therapy

방사선치료 시 전자포털 영상장치를 이용한 잡음전력스펙트럼 수평 및 수직 측정비교

  • Kim, Ki-Won (Department of Radiology, Kyung Hee University Hospital at Gang-dong) ;
  • Choi, Kwan-Woo (Department of Radiology, Asan Medical Center) ;
  • Jeong, Hoi-Woun (Department of Radiological Technology, Baekseok Culture University) ;
  • Jang, Seo-Goo (Department of Medical Science, Soonchunhyang University) ;
  • Kwon, Kyung-Tae (Department of Radiological Technology, Dongnam Health University) ;
  • Son, Soon-Yong (Department of Radiological Technology, Wonkwang Health Science University) ;
  • Son, Jin-Hyun (Department of Radiological Technology, Shingu University) ;
  • Min, Jung-Whan (Department of Radiological Technology, Shingu University)
  • 김기원 (강동경희대병원 영상의학과) ;
  • 최관우 (서울아산병원 영상의학과) ;
  • 정회원 (백석문화대학교 방사선과) ;
  • 장서구 (순천향대학교 의과학과) ;
  • 권경태 (동남보건대학교 방사선과) ;
  • 손순룡 (원광보건대학교 방사선과) ;
  • 손진현 (신구대학교 방사선과) ;
  • 민정환 (신구대학교 방사선과)
  • Received : 2016.04.30
  • Accepted : 2016.06.23
  • Published : 2016.06.30
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Abstract

The quality assurance (QA) is very important for diagnostic field and radiation therapy field to evaluate the characteristic of devices. The purpose of this study was to compare different NPS methodologies results which are measuring NPS with regard to horizontal and vertical directions by using megavoltage X-ray energies. The NPS evaluation methods were applied to the International Electro-technical Commission standard (IEC 62220-1). The electronic portal imaging devices (EPID) devices such as Siemens BEAMVIEW$^{PLUS}$, Elekta iViewGT and Varian Clinac$^R$ iX aS1000 were used. NPS data were expressed by corresponding each frequency about average of noise value corresponding the each frequency, and NPS were evaluated quantitatively by totaling up the noise values of average frequency which are on horizontal and vertical directions. In NPS results for Elekta iViewGT, NPS of horizontal and vertical by using 4 methods were indicated the difference of 3~5% between horizontal and vertical direction. In the results of Siemens BEAMVIEW$^{PLUS}$ and Varian Clinac$^R$ iX aS1000, the NPS of horizontal and vertical direction were indicated the difference of 15% when averaging the whole values. This study were evaluated the NPS of each devices by totaling up the noise values of average frequency which are on horizontal and vertical directions suggesting the quantitative evaluation method using the data.

영상화 품질향상은 방사선 치료영역과 진단영역의 영상화 검사와 같이 quality assurance (QA) 장비들의 특성평가에 매우 중요한 요소이다. 본 연구의 목적은 치료장비의 megavoltage X-ray 에너지를 사용하여 측정방법에 있어서 NPS에 대한 수평, 수직적인 방법에 대한 측정결과를 비교 평가하는 것이다. 잡음전력스펙트럼 평가 방법들은 국제 전기 규격 international electro-technical commission (IEC 62220-1) 기준을 사용하여 치료 영역에 적용되었다. 사용한 전자포털 영상장치(electronic portal imaging device, EPID)는 Siemens BEAMVIEW$^{PLUS}$, Elekta iViewGT 그리고 Varian Clinac$^R$ iX aS1000이었다. 데이터들로부터 각각의 주파수 값에 대응하는 노이즈 값들의 평균에 대해서, 각각의 주파수 별로 대응해서 표현하였으며, 수평 수직되어있는 주파수별 평균값의 노이즈값을 합산해서 정량적으로 장비마다 비교 평가하였다. 결과값은 Elekta iView에서 4가지 방법론에 의한 가로방향에서의 horizontal측정된 NPS값과 vertical 세로방향에서의 측정치는 비슷한 경향성에 따라서 horizontal과 vertical값은 3~5%정도의 차이가 있었으며, Siemens BEAMVIEW$^{PLUS}$, Varian Clinac$^R$ iX aS1000에서 horizontal측정된 NPS값과 vertical 측정된 NPS값은 편차의 차이가 전체값의 평균으로 했을 시 horizontal과 vertical값은 15%정도의 차이가 나타남을 보였다. 본 연구에서는 수평 수직되어있는 주파수별 평균값의 노이즈값을 합산해서 정량적으로 장비마다 비교 평가하였으며, 정량적인 평가방안을 제시하였다는 점을 둘 수 있다.

Keywords

References

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