What is the energy resolution range for energy window calibration in PET?

In positron emission tomography (PET), the energy resolution range for energy window calibration is crucial for optimizing the detection of gamma photons emitted from positron annihilation events. During this process, the energy calibration helps to define the energy windows that will be used to discriminate true photon events from scatter and random coincidences.

The correct energy resolution range of 425-600 keV is designed to encompass the typical energy levels of the coincident gamma rays detected in PET imaging, particularly considering the annihilation photons which have an energy of 511 keV. This range allows for effective detection of the photons while minimizing background noise and ensuring that accurate imaging is achieved. Acquiring data within this specific energy window helps to improve image quality by filtering out lower energy interactions that do not correspond to the expected photon energies from positron annihilation.

In comparison, the other ranges do not adequately encompass the optimal region for photon detection and calibration within the context of PET imaging. The calibration needs not only to accommodate the main photon energy but also to provide a degree of margin for variations in detected photon energies, thus ensuring optimal performance of the PET system.