Sensitivity evaluation of positron emission tomographs

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Positron Emission Tomography (PET)

Background:

• Accurate sensitivity determination is crucial for quantitative analysis in PET imaging.
• Image reconstruction filters can influence quantitative accuracy by affecting scatter fraction estimation.
• The ECAT 933/4-16 scanner is a widely used PET system.

Purpose of the Study:

• To determine the sensitivity of an ECAT 933/4-16 scanner.
• To evaluate the impact of different image reconstruction filters on scanner sensitivity.
• To assess the relationship between reconstruction filters, scatter fraction, and sensitivity.

Main Methods:

• Sensitivity was measured following EEC Concerted Action guidelines.
• PET images were reconstructed using various filters (e.g., Ramp, Shepp, smoothing filters).
• Regions of Interest (ROIs) were analyzed to compare reconstructed counts with phantom activity.

Main Results:

• Uncorrected scanner sensitivity was independent of the reconstruction filters used.
• Sensitivity corrected for scatter fraction showed dependency on the reconstruction filter.
• Non-smoothing filters (Ramp, Shepp) resulted in higher corrected sensitivity due to lower reconstructed scatter fractions.

Conclusions:

• Image reconstruction filter choice significantly impacts scatter fraction correction and thus, corrected PET scanner sensitivity.
• Non-smoothing filters may offer improved quantitative accuracy by minimizing scatter effects.
• Standardized sensitivity measurements should consider the influence of reconstruction algorithms in PET.