Fig. 12From: Technical opportunities and challenges in developing total-body PET scanners for mice and ratsFundamental spatial resolution versus ring diameter and detector resolution, assuming a 0.102Â mm FWHM positron annihilation point distribution from the 18F label source [155]. The resolutions are worse for larger ring diameters, which is caused by the noncollinearity of the annihilation photons as shown in formula (1) [18]Back to article page