針孔式單光子放射電腦斷層掃描系統(SPECT)為生醫影像研究上的重要利器，在實際系統開發建構前，若能以模擬計算獲得系統的取樣完整性與影像品質評估，可有效降低硬體開發試誤的成本。基於此想法，本研究引入七針孔的單光子放射顯微鏡系統來進行模擬上的取樣完整性演算及影像重建品質的分析。 在模擬的演算上，取樣完整性係數(Sampling Completeness Coefficient, SCC)是由圖伊條件(Tuy’s Condition)在電腦斷層掃描系統下所建立，並修改適用於SPECT系統。我們使用此方法評估七針孔單光子放射電腦斷層掃描系統之取樣完整性，包含圓軌跡與螺旋軌跡的掃描，投影至直徑40 mm之閃爍晶石偵測器，來完成取樣完整性之評估。 而影像品質分析上，我們藉由實驗取得之通量模型與寬度模型數據，建立影像系統矩陣(H matrix)，搭配自主建立之假體模型(Phantom)及最大可能性之期望值最大化演算法(MLEM)來進行影像投影與重建，評估在圓軌跡與螺旋軌跡下之影像品質。並由結果的分析可初步驗證，在進行影像系統建立或實際取像前，可以由取樣完整性的分析來評估不同系統設計或不同軌跡繞行下之影像品質，節省系統開發所需的花費與時間。 ;Abstract In this thesis, we use the seven-pinhole single photon emission microscope system (SPEM), which is a version of single photon emission computed tomography (SPECT) system, to simulate the sampling completeness coefficient and analyze the image quality. In order to lessen the development cost, we simulated the system architecture to predict the results and make sure that the system works properly. In the simulation process, the Sampling Completeness Coefficient (SCC) is based on Tuy’s condition in a cone-beam CT system. We utilize it to evaluate the SCC of seven-pinhole single photon emission microscope system when an object is projected with circular and helical orbits onto the scintillator with 40 mm diameter. To acquire high quality images, we need an accurate imaging system matrix, called H matrix, which is established from the flux and width models by using the experimental data. The H matrix is used to forward-project the simulated phantoms and the Maximum Likelihood Expectation Maximization (MLEM) algorithm is used for image reconstruction. The results show that SCC values are consistent with the reconstructed image quality. Therefore, the SCC analysis can be used to evaluate the system architecture, in terms of geometry designs and orbit paths, before building the actual system to lessen the cost and save time.
