Dear Castor users:
I am currently simulating with GATE an IQ phantom using two scanners. One scanner has a 4x larger axial FOV than the other. While the image from the smaller scanner (A) is correct, the larger scanner (B) results in a non-uniform background, particularly around the central spheres, it can be seen in the attached images.
Please, if someone has managed to do it and can help me, I would appreciate it.
Best Regards!
Miriam
Hello Miriam,
Have you applied Normalization in CASToR recon? It is introduced to correct artifacts caused by the nonuniformity of sensitivity. If you do not apply normalization, ring & star artifacts may appear.
Best,
Xin
Hello Xin!
Thank you very much for your answer. In fact no, I did not apply the normalization in the CASToR recon. I have been reading about how to introduce the normalization factors but it is still not clear to me.
Please, if anyone has managed to perform a normalization correction from a GATE simulation and can give me some guidance on what steps I have to follow, I would appreciate it.
Best Regards!
Miriam
Hi Miriam,
You can follow the methods of normalization as introduced in " Pepin, Audrey et al. “Normalization of Monte Carlo PET data using GATE.” 2011 IEEE Nuclear Science Symposium Conference Record (2011): 4196-4200."
You will find details about normalization factor calculation in the article. When you have normalization factors for each LOR, you can provide a normalization data file into CASToR recon.
Best!
Xin