Question

Discuss and describe the factors affecting spatial resolution (SR) in multiple ring PET systems

Answer 1

You must be aware of PET, it stands for positron emission tomography and the fundamental limits or the factors affecting spatial resolution(SR) have been understood for many years.

Before heading toward the factors, let me shed some light on the above two.

It is possible to have an SR certainly in a detector to be of few millimeters as it is determined by crystal cross-section while a full PET scanner is made as a cylindrical assembly of block detectors in a ring structure.

For a PET image quality, Spatial Resolution plays an important role. There are various factors affecting spatial resolution in multiple ring PET systems.

• The first is the Positron path : Based on its initial energy ,the positron travels some distance from decay to the points of annihilation
• The second is Non-Collinearity : This affects the SR as annihilation photons are not emitted exactly with 180 degrees apart.This limit is not reducible
• The third is the Detector : The smaller the detectors , the better will be the spatial resolution.The main issue is due to the radial thickness of the detectors.

Other factors are:

• Decoding errors
• Crystal Penetration
• Reconstruction algorithm

The actual size of the detector element mostly plays an important role in determining a resolution.The current high-performance PET scanners have multiple rings of detectors.