Journal of the Korean Society of Radiology (한국방사선학회논문지)

The Korean Society of Radiology (한국방사선학회)
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Analysis of Noise Power Spectrum According to Flat-Field Correction in Digital Radiography

디지털 의료영상에서 Flat-Field 보정에 따른 Noise Power Spectrum 분석

  • Lee, Meena (Department of Radiological Science, Catholic University of Daegu) ;
  • Kwon, Soonmu (Department of Radiological Science, Catholic University of Daegu) ;
  • Chon, Kwon Su (Department of Radiological Science, Catholic University of Daegu)
  • 이미나 (대구가톨릭대학교 방사선학과) ;
  • 권순무 (대구가톨릭대학교 방사선학과) ;
  • 천권수 (대구가톨릭대학교 방사선학과)
  • Received : 2013.05.12
  • Accepted : 2013.06.21
  • Published : 2013.06.30
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Abstract

The pixels used in a digital X-ray detector have different sensitivities and offset values. A non-uniform image is consequently obtained. Flat-field correction was introduced to resolve this problem and carried out image preprocessing in a digital imaging system. Nevertheless, the non-uniform images caused by several reasons have been being occasionally acquired. In this study, the non-uniform images acquired in digital imaging systems were applied to flat-field correction, and NPSs were calculated and analyzed with those images before and after correction. It was confirmed that low frequency noise were effectively eliminated.

엑스선 디지털 검출기의 내부 픽셀들은 조금씩 다른 감도와 오프셋 변동을 가지게 되어 불균일한 영상이 얻어진다. 이러한 문제를 해결하기 위해서 flat-field 보정 방법이 개발되었고, 이는 디지털 의료 영상 시스템의 전처리 과정에서 필수적으로 수행된다. 그럼에도 불구하고 여러 가지 이유로 균일하지 않은 영상이 획득되는 경우가 종종 발생한다. 본 연구에서는 디지털 의료 영상 장비에서 획득된 불균일한 영상에 flat-field 보정을 다시 적용시켜 화질이 개선되는 것을 확인하였다. 그리고 객관적인 화질의 평가를 위해 보정 전후의 NPS를 각각 산출하여 비교하였다. 주파수 영역에서 잡음의 변화를 분석한 결과 저주파수 성분의 잡음이 flat-field 보정 후에 크게 제거된 것을 확인할 수 있었다.

Keywords

References

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