Optimization of gamma radiation detectors for medical imaging. Time-of-flight positron emission tomography

Introduction
Innovative functional imaging technologies are contributing to the CEA's ‘Medicine for the Future’ priority. Positron emission tomography (PET) is a nuclear medical imaging technique widely used in oncology and neurobiology. The decay of the radioactive tracer emits positrons, which annihilate into two photons of 511 keV. These photons are detected in coincidence and used to reconstruct the distribution of tracer activity in the patient's body.
We're proposing you to contribute to the development of an ambitious, patented technology: ClearMind. The first prototype is in our laboratories. This gamma photon detector uses a monolithic scintillating crystal of high density and atomic number, in which Cherenkov and scintillation photons are produced. These optical photons are converted into electrons by a photoelectric layer and multiplied in a MicroChannel plate. The induced electrical signals are amplified by gigahertz amplifiers and digitized by SAMPIC fast acquisition modules. The opposite side of the crystal will be fitted with a matrix of silicon photomultiplier (SiPM).
Today we have our first prototype, and we are preparing two more.

The proposed work
You will work in an advanced instrumentation laboratory in a particle physics environment .
The first step will be to optimize the "components" of ClearMind detectors, in order to achieve nominal performance. We'll be working on scintillating crystals, optical interfaces, photoelectric layers and associated fast photodetectors (MCP-PMT and SiPM), and readout electronics.
We will then characterize the performance of the prototype detectors on our measurement benches, which are under continuous development. The data acquired will be interpreted using in-house analysis software written in C++ and/or Python.
Finally, we will compare the physical behavior of our detectors to Monté-Carlo simulation software (Geant4/Gate).
A particular effort will be devoted to the development of ultra-fast scintillating crystals in the context of a European collaboration.

Supervision
The successful candidate will work under the joint supervision of Dominique Yvon and Viatcheslav Sharyy (DRF/IRFU & BIOMAPS). The CaLIPSO group at IRFU & BIOMAPS specializes in the development and characterization of innovative PET detectors, including detailed detector simulation. As part of the project, we are working closely with IJCLabs in Orsay, which is developing our readout and acquisition electronics, CEA/DM2S, which is working in particular on trusted AI algorithms, CPPM in Marseille, which is evaluating our detectors under PET imaging acquisition conditions, and UMR BIOMAPS (CEA/SHFJ), working on image calculation algorithms.

Requirements
Knowledge of the physics of particle-matter interaction, radioactivity and the principles of particle detectors is essential. A strong interest in instrumentation and laboratory work is recommended. Basic programming skills, e.g. C++, Gate/Geant4 physics simulation software, are important.

Skills acquired
Good knowledge of state-of-the-art particle detector and positron emission tomography technologies. Simulation principles and techniques for particle-matter interaction and detection systems. Analysis of complex data.

Contact
Dominique Yvon, dominique.yvon@cea.fr
Viatcheslav Sharyy, viatcheslav.sharyy@cea.fr