正子斷層造影對於長時間觀測放射性藥物在生物體內的分佈並準確定量是很有潛力的，然而長時間觀測對於目前臨床上主要使用的核種F-18是不利的，因F-18的半衰期只有110分鐘。I-124對於長時間的生物分佈追蹤是有利的，因為I-124的半衰期為4.2天，然而由於複雜的衰變，造成定量上的困難。雖然目前有許多修正法已提出，但仍然沒有一簡單、快速且能應用於不同情況的修正方法。
本篇提出一新的修正法-射束擋塊法，這是在受測體周圍擺放材料為鎢的射束擋塊，只會對主射束造成衰減，對於非真實事件的影響很小，因此非真實事件可利用有於沒有射束擋塊的掃描求得。
蒙地卡羅模擬圓柱形假體與zubal假體並比較射束擋塊法與文獻提出的方法(DLC+BG+SSS)，可發現重建影像不論在對比、正規化標準差與平均回復係數，都是射束擋塊法較好。
因為非相關隨機事件可用延遲通符時間修正，本篇額外計算了延遲同符時間修正加射束擋塊法的影像評估指標，發現此法對於非真實事件的估計能更加準確，然而在影像評估指標上的改進有限。
本篇提出一簡單且快速的修正法期望能有效修正非真實事件在正子造影中的影響。

Positron emission tomography (PET) is potential for accurate quantification and following up long-term biological process. However the most common used radionuclide F-18 in clinic, which have short half life about 110 min, is not proper for long-term observation the biodistribution in subjects. I-124 is a proper candidate for this purpose because of the longer half-life. Quantification is difficult because of the complex decay scheme. Although there are many correction methods have been proposed, there still not a simple, quick method to correct the non-true events simultaneously.
Here we propose a new method, the beam stopper correction method, to correct the non-true events caused by I-124. The principle of this method is to assume the primary events are blocked by the stoppers, while the non-true events are not blocked by the stoppers. To fulfill these conditions, we need to choose the diameter of stoppers as small as possible, and the stopper should be put close to the subjects.
Comparison the beam stopper method and traditional method(delayed window approach + background subtraction + single scatter simulation simulation) with the cylinder and Zubal phantom, finding the beam stopper method have better results in different image quality indices. These could be seen in the text.
Because of the DLC has a good estimation in non-correlated random events, combining the beam stopper method and DLC to correct the non-true events. This method will good in estimate the non-true events fraction, but for the other image quality indices are almost the same for beam stopper method only.
A new method is proposed to correct the non-true events for I-124 in PET.

目錄
中文摘要 Ⅰ
英文摘要 Ⅱ
誌謝 Ⅲ
目錄 Ⅴ
圖目錄 Ⅸ
表目錄 XI

第一章 緒論 1
1.1基本概念 1
1.1.1前言 1
1.1.2正子斷層造影基本原理 2
1.1.3正子射源 3
1.1.4 同符事件 5
1.2實驗動機、目的與架構 7
1.2.1實驗動機 7
1.2.2 實驗目的 8
1.2.3論文架構 9
第二章 文獻回顧 10
2.1非真實事件修正法 10
2.1.1非相關隨機事件修正法 10
2.1.2背景修正 (background correction) 11
2.1.3散射事件修正法 14
第三章 材料與方法 16
3.1射束擋塊非真實事件修正法 16
3.1.1原理 16
3.1.2 操作流程 20
3.2模擬實驗 21
3.2.1 蒙地卡羅模擬 21
3.2 影像重建與分析 24
3.2.1 影像重建 24
3.2.2 影響分析 24
3.3非真實事件正弦圖分析 26
3.3.1 非真實事件分率 26
3.3.2 均方誤差 26
3.4延遲時間同符修正+射束擋塊法 26
第四章 研究結果 27
4.1射束擋塊穿透率 27
4.2假體 27
4.2.1非真實事件正弦圖 27
4.2.2重建影像 28
4.2.3量化分析 31
4.2.4非真實事件正弦圖 31
4.3 ZUBAL假體 33
4.3.1非真實事件正弦圖 33
4.3.2重建影像 34
4.3.3量化分析 37
4.3.4非真實事件正弦圖 37
4.4延遲時間同符修正+射束擋塊法的結果 39
4.4.1假體 39
4.4.2 zubal假體 39
第五章 討論 40
5.1 射束擋塊裝置 40
5.2 延遲時間同符修正法+背景扣除+單次散射模擬修正法 40
5.3重建影像結果 40
5.4 活度的選擇 41
5.5 124I附屬加馬射線造成的非真實事件分佈 41
5.6射束擋塊法與延遲時間同符修正+射束擋塊法的結果比較 42
第六章 結論 43
第七章 參考文獻 44

圖目錄
圖1.1 正弦圖形成示意圖 2
圖1.2 124I的衰變圖 5
圖1.3 真實事件與散射事件示意圖 6
圖1.4 同符事件示意圖 7
圖2.1背景扣除示意圖 13
圖2.2為散射示意圖 15
圖3.1射束擋塊非真實事件修正法示意圖 17
圖3.2 空氣掃描橫切面示意圖 18
圖3.3 內差求得非真實事件的示意圖 19
圖3.4 射束擋塊非真實事件修正法流程圖 20
圖3.5 SIMGATE模擬流程圖 22
圖3.6 假體示意圖 23
圖3.7 ZUBAL假體示意圖 24
圖4.1 模擬得到的穿透率分佈 27
圖4.2正弦圖230°位置非真實事件與總訊號的水平剖面圖 28
圖4.3不同修正法重建影像結果。 29
圖4.4 重建影像的水平剖面圖 30
圖4.5重建影像的垂直剖面圖 30
圖4.6 非真實事件正弦圖 32
圖4.7 非真實事件正弦圖水平剖面圖 33
圖4.8正弦圖230°位置非真實事件與總訊號的水平剖面圖 34
圖4.9不同修正法重建影像結果 35
圖4.10重建影像的水平剖面圖 36
圖4.11為重建影像的垂直剖面圖 36
圖4.12非真實事件正弦圖 38
圖4.13非真實事件正弦圖水平剖面圖 39

表目錄
表1.1 不純正子核種 5
表3.1 模擬機型-SIEMENS ECAT EXACT HR+-參數 23
表4.1 重建影像量化結果 31
表4.2 重建影像量化結果 37

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