CRYSP: a total-body PET based on cryogenic cesium iodide crystals

Area of Science:

• Medical Imaging
• Materials Science
• Detector Physics

Background:

• Total Body PET (TBPET) scanners offer high sensitivity, reducing scan times and radiation doses.
• High costs of current TBPET systems limit widespread clinical adoption.
• Rare-earth scintillators are typically used, contributing to system expense.

Purpose of the Study:

• To investigate pure cesium iodide (CsI) monolithic crystals at cryogenic temperatures as a cost-effective alternative for TBPET detectors.
• To assess the performance of cryogenic CsI for TBPET imaging.

Main Methods:

• Pure CsI crystals were operated at cryogenic temperatures (~100 K).
• Light yield, energy resolution, spatial resolution (including DOI), and timing performance were evaluated.
• Monte Carlo simulations were used to model crystal performance.

Main Results:

• Cryogenic CsI achieved a light yield of ~10^5 photons/MeV.
• Energy resolution below 7% and nanosecond-level coincidence time resolution were demonstrated.
• Millimeter-scale spatial resolution in 3D was predicted via simulations, indicating high-performance PET imaging potential.

Conclusions:

• TBPET scanners using cryogenic CsI monolithic crystals can achieve excellent imaging performance.
• This approach offers significantly reduced detector costs compared to existing systems.
• Broader accessibility and accelerated adoption of TBPET in clinical and research settings are anticipated.