Step-and-shoot mode

A SPECT system consists of one or more scintillation cameras mounted to a gantry that can revolve about a fixed horizontal axis (the axis of rotation) " (Fig. 27.13). SPECT studies are usually acquired over a full 360° arc, although myocardial perfusion studies typically use only data from the 180° arc that minimizes tissue attenuation. SPECT acquisitions are performed with the scintillation camera located at preselected angular locations (step-and-shoot mode), or in a continuous rotation mode. In the step-and-shoot mode, the detector rotates to each angular position and collects data in a preselected frame duration while the detector is motionless. In the continuous-rotation mode, the smdy duration is selected and the rotation speed is adjusted to complete the orbit during this time. Projections are collected as the detector rotates and are binned into 60 to 120 frames over 360°. 

With the advent of MDCT, axial step-and-shoot scanning has remained in use for only few clinical ap-phcations, such as head scanning, high-resolution lung scanning, perfusion CT and interventional applications. A detailed theoretical description to predict the performance of MDCT in step-and-shoot mode has been given (Hsieh 2001). 

Hein I, Taguchi K, Silver M D, Kazarna M, Mori I (2003) Feld-kamp-based cone-beam reconstruction for gantry-tilted helical multislice CT. Med Phys 30 3233-3242 Hsieh J (2001) Investigation of the slice sensitivity profile for step-and-shoot mode multi-slice computed tomography. Med Phys 28 491-500... 

Another technique for phase synchronization is the prospective ECG triggering or step-and-shoot mode technique. This technique is widely used for the quantification of the coronary calcium burden (calcium scor-... 

Fig. 15.1a-d. Dualsource CT coronary angiography in a 49-year-old man with a single episode of atypical chest pain. Scanning was performed with in the step-and-shoot mode (mean heart rate 66 bpm). Curved multiplanar reformations of the right coronary artery (a), left anterior descending artery (b), and the left circmnflex artery. (c,d see next page)... 

Scheffel H, Alkadhi H, Leschka S, et al. (2008) Low-Dose CT Coronary Angiography in the Step-and-Shoot Mode Diagnostic Performance. Heart... 

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