Greetings,
As presented in [1], the NEMA NU 4 standard is not perfect. Here, I discuss about the recommendation of [1] for PET spatial resolution. Currently, the NEMA standard proposes to use a point source that is reconstructed with FBP to evaluate a PET system spatial resolution. While using FBP circumvents the ‘iterative dependence’ of spatial resolution, it has one big flaw: it is hard to implement a good one and you will probably never use it again since you need iterative reconstruction for better noise control.
A Hot-Spot phantom offers a good qualitative alternative since we can simply use our eye to define when a sector is resolved. However, it is observer dependent. The solution proposed in [1] is based Hot-Spot resolvability on the Rayleigh Criterion. (Is it optimal for PET imaging? Good question, but I do not have the answer!)
Me and one of my colleagues have implemented an interpretation of that proposal for our use and it is now available on GitHub, see [2]. You give to the script image(s) (e.g. in CASToR format) and a configuration file that describes the sectors/spots of the image(s) and, voilà, you get an analysis of the sector resolvability. (Well, it is not that easy but it should be not that bad.) The ReadMe should be enough to give an idea on how to use it and if there are any problems, do not hesitate to create an issue!
Note that we offer our interpretation of that proposal and that this proposal is only this: a proposal. A good one I believe, but it is not something that was validated by a big committee or equivalent.
In the hope that it saves time for at least one of you!
Best,
Maxime Toussaint
[1] Hallen, P., Schug, D. & Schulz, V. “Comments on the NEMA NU 4-2008 Standard on Performance Measurement of Small Animal Positron Emission Tomographs.”, EJNMMI Phys. 7, 12 (2020). Comments on the NEMA NU 4-2008 Standard on Performance Measurement of Small Animal Positron Emission Tomographs | EJNMMI Physics | Full Text
[2] GitHub - MaxTousss/PetSpatialResolvability