Continuous bed motion on clinical scanner: design, data correction, and reconstruction

With the addition of variable bed speed capabilities, continuous bed motion (CBM) becomes an acquisition generalization for axial sensitivity modeling and therefore a flexible tool in axial local image quality adjustment. In this paper, we describe the principles behind CBM mode planning and its influence on image reconstruction. The data correction method underwent the most changes compared to the commonly used step and shoot (S&S) mode. The CBM normalization array accommodates for activity decay, dead time correction, and the fact that various detector pairs acquire the same data for different durations. The normalization array is computed by simulating the movement of an object through the scanner, assisted by the monitoring of basic scanner acquisition parameters such as the singles rate. The sensitivity, which is the number of counts acquired per image plane, is an intrinsic part of normalization computing. Basic equations to estimate acquisition time at matched sensitivity between single speed CBM and S&S mode are presented. The CBM feature was implemented on a Siemens clinical scanner and initial studies of phantoms and patients are presented. The equivalence of single speed CBM and S&S image quality is demonstrated.