Seret Alain, Flérès David, Firket Olivier, Defrise Michel
Imagerie médicale expérimentale et Centre de Recherche du Cyclotron, Institut de Physique, Université de Liège, Liège 1, Belgium.
Eur J Nucl Med Mol Imaging. 2003 Sep;30(9):1205-10. doi: 10.1007/s00259-003-1213-2. Epub 2003 Jun 17.
This study investigated the feasibility of ordered subsets expectation maximisation (OS-EM) reconstruction of 180 degrees pinhole single-photon emission tomography (SPET) acquired in body contour mode (variable distance between the detector and the axis of rotation for each projection) with or without a tilted detector head. Four non-circular orbits were designed bearing in mind the rotation radius and tilt angle values of previous pinhole SPET acquisitions in patients with circular orbits. The reconstructions were performed using a dedicated OS-EM algorithm. Reconstructed images of line and uniformity phantoms showed that the spatial and uniformity characteristics of the radioactive objects were preserved. In comparison with the circular orbits, the non-circular orbits allowed only a moderate gain (maximum 10%) in resolution. However, body contour pinhole SPET would significantly facilitate the camera set-up and in this way should decrease the camera set-up time, which is an important parameter in patient studies.
本研究调查了在体轮廓模式（每个投影中探测器与旋转轴之间的距离可变）下，有或没有倾斜探测器头的情况下，对180度针孔单光子发射断层扫描（SPET）进行有序子集期望最大化（OS-EM）重建的可行性。考虑到先前在圆形轨道患者中进行针孔SPET采集的旋转半径和倾斜角度值，设计了四个非圆形轨道。使用专用的OS-EM算法进行重建。线和均匀性体模的重建图像表明，放射性物体的空间和均匀性特征得以保留。与圆形轨道相比，非圆形轨道仅能在分辨率上实现适度提高（最大10%）。然而，体轮廓针孔SPET将显著便于相机设置，从而应能减少相机设置时间，这在患者研究中是一个重要参数。
