Traceable point-like Ge/Ga source with a spherically symmetric positron absorber for PET scanners.

A novel traceable point-like Ge/Ga source was developed for calibration of positron emission tomography (PET) scanners. The source was equipped with a spherically symmetric acrylic positron absorber. The physical characteristics of photons emitted from the point-like source were evaluated by Monte Carlo simulation, considering possible geometrical uncertainties. The calibration factor of a clinical PET/CT scanner was evaluated using four manufactured point-like sources as a practical application of the point-like source. The results were consistent with that determined by the conventional cross-calibration method. The traceable point-like Ge/Ga source is expected to be a simple and practical tool for determining the calibration factor and evaluating the physical characteristics of PET scanners.