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.

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