Abstract
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.