The Impact of XRF-Escape on Energy Resolution of NaI: Tl Scintillation Detectors for Medical Imaging or Gamma-Ray Spectroscopy

The effect of escape of X-ray fluorescence from scintillator elemental components on the detector energy resolution is investigated from a spectroscopic standpoint, for monolithic and pixelated crystals. Along with these, any other emissions in a given region of interest were also considered. In present spectral evaluations a range of ratios between the areas of the peaks (XRFesc) to (XRFesc + photoelectric) has been a priori set from 0-50%, according to literature indications, by 10% steps. At the upper extremes of these ratio values, maximum worsening in energy resolution values just below 40%, just above 10% and just below 10% have been estimated for the interest regions of Tc-99 and F-18e Cs-137, respectively. The inter-crystal XRF-escape is suggested to be considered among the effects producing image blurring in segmented scintillators due to the spread of events between neighbor pixels