npsm 새물리 New Physics : Sae Mulli

pISSN 0374-4914 eISSN 2289-0041
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Article

Research Paper

New Phys.: Sae Mulli 2020; 70: 903-907

Published online October 30, 2020 https://doi.org/10.3938/NPSM.70.903

Copyright © New Physics: Sae Mulli.

Development of a Depth Measurement with Two Types of Scintillators

Cheol-Ha BAEK1, Seung-Jae LEE2*

1Department of Radiological Science, Kangwon National University, Samcheok 25949, Korea

2Department of Radiological Science, Dongseo University, Busan 47011, Korea

Correspondence to:sjlee@gdsu.dongseo.ac.kr

Received: August 11, 2020; Revised: August 17, 2020; Accepted: August 17, 2020

Abstract

We have developed a detector that uses two types of scintillators and s photo sensor to measure the depth of interaction. A different type of scintillator was used for each layer, and light generated by interacting with the scintillator was collected using a photo sensor. The energy spectrum of the designed detector was obtained using a DETECT2000 simulation, and the performance of the designed detector was verified through preliminary experiments. As a scintillator, a lutetium oxyorthosilicate (LSO) or a Gadolinium Aluminium Gallium Garnet (GAGG) scintillator was used, and a silicon photomultiplier (SiPM) was used as the photo sensor. In the simulation, the scintillator array was composed of two layers, and a light yield corresponding to gamma ray interactions was generated in each scintillator pixel to obtain a signal to measure the energy spectrum. In the preliminary experiment, the energy spectrum was measured using a single-pixel scintillator, and the result was the photoelectric peak of the GAGG scintillator in the high-energy channel and that of the LSO scintillator in the low-energy channel as in the simulation. Because different photoelectric peaks are formed in the energy spectrum, the positions where the gamma rays and the scintillator interact can be measured, thereby improving the spatial resolution through measurement of the interaction depth.

Keywords: Two types of scintillator, Energy spectrum, SiPM, Depth of interaction, DETECT2000

두 종류의 섬광체와 광센서를 사용하여 반응 깊이를 측정하는 검출기를 개발하였다. 각 층별 서로 다른 종류의 섬광체를 사용하였으며, 섬광체와 상호작용하여 발생된 빛은 광센서를 통해서 획득하였다. DETECT2000 시뮬레이션을 통해 설계한 검출기의 에너지 스펙트럼을 획득하였으며, 기초 실험을 통해 설계한 검출기의 성능을 검증하였다. 섬광체는 Lutetium Oxyorthosilicate (LSO)와 Gadolinium Aluminium Gallium Garnet (GAGG) 섬광체를 사용하였으며, 광센서는 실리콘광전증배관 (Silicon photomultiplier; SiPM)을 사용하였다. 시뮬레이션에서 두 층으로 섬광체 배열을 구성하였으며, 각 섬광체 픽셀에서 감마선 상호작용에 해당하는 빛을 발생시켜 신호를 획득하여 에너지 스펙트럼을 측정하였다. 기초 실험에서는 한 픽셀의 섬광체를 사용하여 에너지 스펙트럼을 측정하였으며, 결과는 시뮬레이션과 동일하게 높은 채널에서 GAGG 섬광체의 광전피크가, 낮은 채널에서 LSO 섬광체의 광전피크가 형성되었다. 에너지 스펙트럼 상에서 서로 다른 광전피크가 형성되므로 이를 구분하여 측정함으로써 감마선과 섬광체가 상호작용한 위치를 측정할 수 있으므로 반응 깊이 측정을 통해 공간분해능의 향상을 이룰 수 있다.

Keywords: 두 종류 섬광체, 에너지 스펙트럼, 실리콘광전증배관, 반응 깊이 측정, DETECT2000

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