Two-detector, asymmetric cone-beam helical SPECT

Whole-body SPECT (single photon emission computed tomography) with a helical scanning orbit is proposed to replace whole-body planar imaging. In order to correct for attenuation and avoid truncation of projection data, the use of asymmetric cone-beam imaging geometries for simultaneous transmission and emission data acquisition is being investigated. At least two detectors are required in order to provide sufficient cone-beam data. If two detectors are used, they must have opposite geometries, and the data sufficiency condition for the cone-beam geometry is such that when a detector rotates “π plus fan-angle”, it should shift axially by a, where a is the detector size projected on the axis of rotation. By using Beacon^TM method, transmission and emission imaging geometries can be different. Various helix pitch requirements are derived here for many imaging geometries and for many detector configurations