MEMS 기술을 이용한 엑스선 영상 센서용 섬광체 패널의 제작 및 특성평가 = Fabrication and Performance evaluation of Pixel-structured scintillators for X-ray image sensors

다국어 초록 (Multilingual Abstract)

The use of X-rays for diagnosis increases in medical practice. The conventional analog-typed X-ray film detectors are rapidly substituted for the digital ones. The introduction of picture archiving and communication systems (PACS) increases demanding digital radiography in many hospital. Digital radiography offers the potential of improved image quality as well as providing opportunities for advances in medical imaging management.
In this study, we have fabricated scintillator panel which convert X-ray into light. Due to the cross-talk in scintillator, the spatial resolution was still limited. The pixel-structured scintillator is fabricated by MEMS technology. The pixel-structured scintillator have been designed and fabricated and the difference of the spatial resolution according to the pixel size has been evaluated. The material of pixel-structured scintillator used silicon and polyethylene. The pixel-structured scintillator of silicon was fabricated by photolithography and deep reactive ion etching (DRIE) process. The pixel-structured scintillator of polyethylene was fabricated by hot embossing. The terbium doped gadolinium oxysulfide (Gd2O2S:Tb) that can be processed at room temperature has been used as a scintillator material. To evaluate their image quality, this study acquired CC (characteristic curve), MTF (modulation transfer function) and DQE (detective quantum efficiency).
This study verifies that the pixel-structured scintillator is effective against the over-spreading of the converted visible light. However, the sensitivity of fabricated scintillator panel is much lower than sensitivity of commercial screen. NNPS and DQE were also much lower than them of commercial screen. Therefore, the next study is needed to find out the method of the sensitivity improvement of scintillator panel.

목차 (Table of Contents)

• 제 1 장 서론 1
• 1.1 연구 배경 1
• 1.2 선행 연구 분석 2
• 1.3 연구 목적 3
• 제 2 장 섬광체 패널 이론적 배경 7
• 2.1 디지털 엑스레이 영상시스템의 검출방식 7
• 2.1.1 직접변환방식(Direct Conversion Method) 7
• 2.1.2 간접변환방식(Indirect Conversion Method) 8
• 2.2 무기 섬광체의 발광메커니즘 8
• 제 3 장 섬광체 패널 제작 공정 및 결과 15
• 3.1 마스크 설계 15
• 3.2 마이크로 픽셀 구조물 제작 16
• 3.2.1 실리콘 마이크로 픽셀 구조물 제작 16
• 3.2.2 니켈 몰드 제작 17
• 3.2.3 PE 마이크로 픽셀 구조물 제작 19
• 3.3 섬광체 도포 21
• 3.4 섬광체 패널 제작 결과 21
• 제 4 장 섬광체 특성 평가 및 결과 49
• 4.1 특성평가 이론 49
• 4.1.1 특성곡선 (Characteristic Curve) 49
• 4.1.2 MTF (Modulation Transfer Function) 49
• 4.1.3 NPS (Noise Power Spectrum) 49
• 4.1.4 DQE (Detective Quantum Efficiency) 50
• 4.2 섬광체 패널의 특성평가 시스템 51
• 4.3 결과 및 고찰 51
• 4.3.1 특성곡선 (Characteristic Curve) 51
• 4.3.2 MTF (Modulation Transfer Function) 52
• 4.3.3 NPS (Noise Power Spectrum) 53
• 4.3.4 DQE (Detective Quantum Efficiency) 53
• 제 5 장 결론 66
• 참 고 문 헌 68
• Abstract 71