Gating threshold value determination for the motion gating of positron emission tomography/computed tomography

Gating technique is a common way to reduce the effect of breathing movement in the imaging of positron emission tomography/computed tomography (PET/CT). Gating threshold value selection will directly affect the quality level of respiratory motion gating. Most methods of gating threshold value selection are implemented by manually determining, which easily leads to an inaccurate gating. Therefore, exploring an effective method of determining the gating threshold value for respiratory motion gating is very important. In this study, a method to automatically determine the threshold value by the slope rate relationship between the adjacent absolute errors of coincidence events was proposed. We use geant 4 application tomographic emission (GATE) software package to simulate realistic PET/CT scanner, and build geometry phantom for respiratory motion simulation. Compared with the manually threshold value determination, the proposed method can make the result of gating correction closer to the real situation. The results prove that the method of automatic determination the threshold value can efficiently and automatically determine the threshold value, and overcome the limitation of the manually threshold value determination.