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Design of DOI Detector Module for PET through the Light Spread Distribution

빛 분포를 통한 양전자방출단층촬영기기의 반응 깊이 측정 검출기 모듈 개발

  • Lee, Seung-Jae (Department of Radiological Science, Dongseo University) ;
  • Baek, Cheol-Ha (Department of Radiological Science, Kangwon National University)
  • 이승재 (동서대학교 방사선학과) ;
  • 백철하 (강원대학교 보건과학대학 방사선학과)
  • Received : 2018.09.05
  • Accepted : 2018.10.31
  • Published : 2018.10.31

Abstract

A depth of interaction(DOI) detector module using a block scintillator and a pixellated scintillator was designed, and layer discrimination ability was calculated using DETECT2000. The block scintillator was used to improve the sensitivity and the spatial resolution was improved by measuring the DOI. The DOI was measured by analyzing the signal characteristics of each channel of the changed distribution of light. The detector module was composed to the block scintillator in the top layer and the pixellated scintillator in the bottom layer, which changes the distribution of light generated from a scintillator interacting with a gamma ray. In the flood image, the top layer was able to acquire the image at the position similar to the position of the bottom layer because the bottom layer consist of the pixellated scintillator. By using the Anger algorithm, the 16 channel signal was reduced to 4 channels to facilitate the analysis of the signal characteristics. The layer discrimination was measured using a simple algorithm and the accuracy was about 84% for each layer. When this detector module is used in preclinical PET, the spatial resolution at the outside of the field of view can be improved by measuring the DOI.

블록형 섬광체와 픽셀형 섬광체를 이용한 반응 깊이 측정 검출기를 설계하였으며, 층 구분 능력을 DETECT2000을 사용하여 측정하였다. 블록형 섬광체를 사용하여 민감도를 향상했으며, 반응 깊이를 측정함으로써 공간분해능을 향상했다. 위층은 블록형으로 아래층은 픽셀형 섬광체를 위치시켜 감마선과 반응한 섬광체에서 발생한 빛의 분포를 변화시켰으며, 변화된 빛의 분포의 채널별 신호 특성 분석을 통해 반응 깊이를 측정하였다. 아래층을 픽셀형 섬광체로 구성하여 평면 영상 획득 시 위층의 블록형 섬광체에서도 픽셀형 섬광체의 위치와 비슷한 곳에서 영상을 획득할 수 있었다. 앵거 알고리듬을 사용하여 16채널의 신호를 4개의 채널로 감소시켜, 신호 특성 분석을 용이하게 하였으며, 층 구분은 간단한 알고리듬을 사용하여 측정하였고 층별 약 84%의 측정 정확도를 보였다. 본 검출기를 전임상용 PET에서 사용할 경우 반응 깊이 측정을 통해 검출 시야 외곽에서의 공간분해능을 향상할 수 있을 것이다.

Keywords

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