本論文利用光學模擬軟體ASAP來模擬單光子放射顯微鏡系統(SPEM)的針孔穿隧效應。單光子放射顯微鏡系統的組成包括高空間解析度的針孔式準直儀、碘化銫閃爍晶體、電子增益電荷耦合元件(EMCCD)和高質量光影像縮倍管(DM Tube)。本論文主要是討論伽瑪射線在通過針孔時所產生的針孔穿隧效應，在非完全通過針孔而進入具有高衰減係數的針孔邊緣時，讓偵測器接收到比實際影像更大的投影點，進而對成像品質造成影響。本實驗用ASAP來模擬這種實際發生的影響，將模擬出的投影影像進行高斯模糊函數擬合進而建立出成像模型。 成像模型包含三種模型，即通量模型、寬度模型和主軸角度模型，並透過投影影像找到的投影重心即可建立出一個影像系統矩陣，用ASAP模擬出的針孔穿隧只要改變幾何參數及衰減係數，即可輕易的變更針孔的數量、位置與材料，來提升針孔設計的多樣性。將解析度假體不同投影角度的投影影像，利用以成像模型建立的影像系統矩陣及序列子集之期望值最大化演算法進行迭代運算，藉由重建出的圖像來評估影像系統的解析度，和建立出這個影像系統矩陣的針孔穿隧模型及成像模型的準確性。 ;This study utilizes the optical simulation software (Advanced Systems Analysis Program, ASAP) to simulate the pinhole tunneling effect in Single Photon Emission Microscope (SPEM). The SPEM system consists of a high spatial resolution pinhole collimator, a cesium iodide scintillation crystal, an Electron-Multiplying Charge-Coupled Device (EMCCD), and a high-quality optical image demagnifier (DM Tube). The main focus of this study is to discuss the pinhole tunneling effect caused by gamma rays passing through the pinhole. When gamma rays partially pass through the pinhole and enter the high-attenuation edge of the pinhole, the detector receives larger projections than the actual images, thus affecting the imaging quality. In this experiment, ASAP is used to simulate this actual effect. The simulated projection images are then fitted into Gaussian blur functions to establish an imaging model. The imaging model consists of three components: the flux model, the width model, and the principal angle model. Additionally, by identifying the projected centroid from the projection images, an imaging system matrix can be established. The pinhole tunneling effect simulated by ASAP allows for easy adjustment of the pinhole′s quantity and position by simply changing the geometric parameters and attenuation coefficients, thereby enhancing the diversity of pinhole design. The projection images of a resolution phantom at different projection angles are reconstructed by using the image system matrix established by the imaging model and the ordered subset expectation maximization algorithm. The reconstructed images are then evaluated to assess the resolution of the imaging system and the accuracy of the pinhole tunneling model and the imaging system matrix.
