Positron range in PET imaging: non-conventional isotopes.

Area of Science:

• Nuclear Medicine
• Medical Imaging
• Radiochemistry

Background:

• Positron emission tomography (PET) increasingly utilizes longer-lived radionuclides.
• High-energy positrons and gamma rays from these isotopes can degrade PET image quality.
• Understanding positron range distribution is crucial for accurate PET imaging.

Purpose of the Study:

• To investigate the positron range distribution for several long-lived PET isotopes.
• To develop analytic functions to describe these distributions.
• To assess the applicability of existing models to new isotopes.

Main Methods:

• Utilized existing Monte Carlo simulations of positron interactions in water.
• Empirically described probability distributions using analytic displacement functions.
• Derived distributions for isotopes including (22)Na, (89)Zr, (124)I, and (64)Cu.

Main Results:

• Analytic distribution functions previously developed for conventional isotopes were also applicable to non-conventional, long-lived isotopes.
• Parameters for certain isotopes ((120)I, (124)I, (89)Zr, (52)Mn, (64)Cu) were less accurately predicted by mean positron energy alone.
• Both conventional and non-conventional range distributions can be described by simple analytic expressions.

Conclusions:

• Simple analytic expressions can describe positron range distributions for both conventional and long-lived PET isotopes.
• These findings can enhance PET image reconstruction software, improving spatial resolution and quantitative accuracy.
• The study provides a foundation for better utilization of long-lived radionuclides in PET imaging.