# Monte Carlo study of the Coincidence Resolving Time of a liquid xenon PET scanner, using Cherenkov radiation

## TL;DR

This study uses Monte Carlo simulations to demonstrate that liquid xenon can enable Cherenkov-based TOF-PET with an intrinsic coincidence resolving time around 10 ps, significantly surpassing current commercial devices.

## Contribution

The paper introduces a novel approach using liquid xenon and Cherenkov radiation to achieve ultra-fast timing in PET scanners, with detailed simulation analysis of performance.

## Key findings

- CRT can be as low as 10 ps with ideal sensors
- Realistic sensors achieve CRT between 30 and 55 ps
- Performance exceeds current commercial PET timing resolutions

## Abstract

In this paper we use detailed Monte Carlo simulations to demonstrate that liquid xenon (LXe) can be used to build a Cherenkov-based TOF-PET, with an intrinsic coincidence resolving time (CRT) in the vicinity of 10 ps. This extraordinary performance is due to three facts: a) the abundant emission of Cherenkov photons by liquid xenon; b) the fact that LXe is transparent to Cherenkov light; and c) the fact that the fastest photons in LXe have wavelengths higher than 300 nm, therefore making it possible to separate the detection of scintillation and Cherenkov light. The CRT in a Cherenkov LXe TOF-PET detector is, therefore, dominated by the resolution (time jitter) introduced by the photosensors and the electronics. However, we show that for sufficiently fast photosensors (e.g, an overall 40 ps jitter, which can be achieved by current micro-channel plate photomultipliers) the overall CRT varies between 30 and 55 ps, depending of the detection efficiency. This is still one order of magnitude better than commercial CRT devices and improves by a factor 3 the best CRT obtained with small laboratory prototypes.