PET Imaging Resolution: Lower E(max) for Superior Image Resolution

[BobP]

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]

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