섬광 픽셀의 깊이 방향에 따른 빛 분포 변화 분석을 통한 반응 깊이 측정 검출기 설계 = Design of DOI Detector Through Analysis of Light Distribution Change According to the Depth Direction of the Scintillation Pixel

다국어 초록 (Multilingual Abstract)

A detector for measuring the interaction depth was designed to improve the spatial resolution of a positron-emission tomography (PET) for small animals. The detector composed of a scintillation pixel array was designed and performance-evaluated in accordance with DETECT2000. The interaction depth was measured by analyzing the light distribution change in the photosensor according to the depth direction of the scintillation pixel interacting with gamma rays. The scintillation pixel of the designed detector was composed of a 4 × 4 array with a size of 3 mm × 3 mm and two layers of 5 mm and 15 mm in the depth direction. Various lights generated by interaction with gamma rays were generated by varying the height of the scintillation pixel to obtain light distribution in the photosensor and determine the layer interacting with gamma rays. A lookup table was prepared with the average and standard deviation of the signals obtained from each photosensor. The light at the new location was acquired from the photosensor, and the interaction depth was measured through comparison and analysis with the lookup table using maximum likelihood position estimation. Results showed an accuracy of 89.2%. Given the excellent spatial resolution to apply this detector to the PET for small animals, images with improved performance can be obtained.

국문 초록 (Abstract)

소동물용 양전자방출단층촬영기기의 공간분해능 향상을 위해 반응 깊이를 측정하는 검출기를 설계하였다. 섬광 픽셀 배열로 이루어진 검출기에서 감마선과 상호작용한 섬광 픽셀의 깊이 방향에 따른 광센서에서의 빛 분포 변화를 분석하여 반응 깊이를 측정하기위해, DETECT2000을 통해 설계하고 성능을 평가하였다. 설계한 검출기의 섬광 픽셀은 3 mm × 3 mm의 크기에 깊이 방향으로 5 mm, 15 mm 두 층으로 4 × 4 배열로 구성하였다. 감마선과 상호작용한 층을 판별하기 위해 섬광 픽셀의 높이에 따라 감마선과 상호작용하여 발생된 빛을 발생시켜 광센서에서의 분포를 획득하였으며, 각 광센서에서 획득한 신호의 평균과 표준편차로 순람표를 작성하였다. 새로운 위치에서 발생된 빛을 광센서에서 획득하여, 최대우도함수를 통해 순람표와 비교·분석을 통해 반응 깊이를 측정하였다. 측정 결과 89.2%의 우수한 정확도를 보였다. 본 검출기를 소동물용 양전자방출단층촬영기기에 적용할 경우 우수한 공간분해능을 달성하여, 보다 향상된 영상을 획득할 수 있을 것이다.

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