Infographics / Nuclear Medicine

SPECT acquisition geometry (rotating camera)

A gamma camera head with a parallel-hole collimator rotates on a circular orbit around a patient lying on a couch. At each angle it records a one-dimensional planar projection of the tracer distribution over a 180 to 360 degree arc; faint outlines show the same head at other angles. The set of projections is reconstructed into stacked tomographic slices giving a three-dimensional activity map. Notes state that a single head suffices while extra heads add sensitivity, standard tracers with a photopeak energy window are used, and the tracer distribution must stay fixed during the scan.

SPECT acquisition geometry A gamma camera head with a parallel-hole collimator rotates on a circular orbit around a patient lying on a couch. At each angle it records a one-dimensional planar projection of the tracer distribution over a 180 to 360 degree arc; faint outlines show the same head at other angles. The set of projections is reconstructed into stacked tomographic slices giving a three-dimensional activity map. Notes state that a single head suffices while extra heads add sensitivity, standard tracers with a photopeak energy window are used, and the tracer distribution must stay fixed during the scan. SPECT acquisition geometry rotates 180–360° (step-and-shoot or continuous) planar projection (1-D) one view per angle gamma camera head + parallel-hole collimator tracer distribution — must stay fixed during the scan same head, other angles reconstruction back-projection / iterative tomographic slices 3-D activity map One rotating head is enough; adding a 2nd/3rd head raises sensitivity → same counts in ½ or ⅓ the time. Uses standard gamma-camera tracers; an energy window on the photopeak suffices, not monoenergetic emission. SPECT is count-hungry: the whole study needs more total counts than a single static planar image.
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