Evolving SPECT-CT technology.

Both hardware and software developments have seen single photon emission computed tomography (SPECT)/X-ray computed tomography (CT) technology grow at a rapid rate. Such growth has been fuelled by the need for clinical applications and has provided inspiration for clinical developments, particularly with the expanding role of theranostics. Developments such as whole-body quantitative reconstructions, digital detectors, and recent multidetector 3D geometry have allowed SPECT to become comparable to PET on a number of fronts, with a particularly powerful role in biodistribution and dosimetry studies for both planning and evaluating radionuclide therapy. Whilst there remain fundamental challenges for SPECT such the limited spatial resolution and sensitivity, the unique opportunity to image long-lived radioisotopes and simultaneous multi-tracer studies, together with easily accessible equipment, makes SPECT/CT a valuable clinical asset. This review discusses developments in SPECT/CT technology and their clinical impact.