# PET imaging resolution

Hi, my lecturer said that in PET imaging, the image resolution is superior when the E(max) of the positrons is lower. Why should this be?
Thanks

gleem
A lower positron energy would mean that the positron would not travel as far from the site of origination before it annihilated. i.e., remaining in the area where the radioisotope was accumulating.

BobP
A lower positron energy would mean that the positron would not travel as far from the site of origination before it annihilated. i.e., remaining in the area where the radioisotope was accumulating.
Seems so obvious now you say it! thanks so much

Dale
Mentor
2020 Award
There is also a second order effect. The higher the positron energy the more the paths of the two photons deviate from a single straight line

BobP
There is also a second order effect. The higher the positron energy the more the paths of the two photons deviate from a single straight line
Thank you