Description of PET and types of PET

Uses Beta decay which emits a positron which annihilates with an electron.

http://tech.snmjournals.org/cgi/content-nw/full/29/1/4/F1

Detector surrounds the emission site and emitted photons are received by each side of the detector.
The location of each annihilation is inferred from a line integral.
This is done using many annihilations to produce an estimated shape of the positron rich area.


PEPT Positron Emission Particle Tracking
Able to track a tracer particle with velocity up to 2m/s.
Can locate particle to within 5mm 250 times each second.
Uses a detector on each side of the sample and can follow the tracer on rails.
tracer particle roughly 1mm diameter.

though promising for its ability to track particles, the use seems limited to rolling drum flow and twin screw extruders.

SPECT Single Photon Emission Computational Tomography
Used to give true 3D images presented as cross sections
Can make use of multiple energy windows to dual tracer imaging. (more than 2?) imaging multiple radionuclides.


References:

Np.ph.bham.ac.uk, (2015). Positron Imaging Centre. [online] Available at: http://www.np.ph.bham.ac.uk/pic/pept [Accessed 12 Nov. 2015].
Rahmim, A. and Zaidi, H. (2008). PET versus SPECT: strengths, limitations and challenges. Nuclear Medicine Communications, 29(3), pp.193-207.