Analytical study of performance in a 3D PET scanner.

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Biomedical Engineering

Background:

• Positron Emission Tomography (PET) systems with high spatial resolution often have low ring sensitivity.
• Multi-ring PET systems can improve sensitivity by removing interslice collimators, but this increases scatter and accidental event rates.

Purpose of the Study:

• To evaluate the performance of a small animal PET scanner (10 cm diameter) with and without interplane collimators.
• To compare volumetric versus multi-slice configurations for small animal imaging.

Main Methods:

• Analytical evaluation of incident event rates for singles and coincidences (true, scatter, accidental).
• Performance assessment based on true/single ratio, scatter fraction, accidental fraction, image contrast, and noise effective sensitivity.
• Evaluation across various source sizes and activities.

Main Results:

• Removing collimators increased scatter fraction by 3-fold and accidental fraction significantly for larger sources.
• Image contrast was inferior in the volumetric configuration due to higher scatter and accidental rates.
• Noise effective sensitivity significantly improved in the volumetric configuration, especially for small, central sources.

Conclusions:

• The volumetric configuration, despite higher scatter and accidental rates, is more advantageous for small animal PET imaging.
• The gain in sensitivity in the volumetric configuration outweighs the loss in accuracy.
• This configuration is particularly beneficial for imaging small laboratory animals.