In the last years, there has been a growing interest in the use of Compton cameras for nuclear medicine applications due to their high detection efficiency and their ability to simultaneously detect multi energy gamma-ray emitting radioisotopes. Even if several prototypes have been built [Tashima 2022], the high-performance requirements in terms of energy, time and spatial resolution for clinical medical applications have not yet been met. These imaging devices need to be further investigated and optimized to reach the clinical standards for which accurate Monte Carlo simulations are required. To this end, the Compton camera module (CCMod, [Etxebeste 2020]) developed within GATE/Geant4 [Sarrut 2021] Monte Carlo simulation toolkit will be employed. This module facilitates the investigation of CC systems and the comparison between different prototypes in an environment that allows to simulate realistically medical applications The quality of the image generally reconstructed by means of iterative reconstruction (CoReSi software in CREATIS [Maxim 2016]) is the final endpoint. A preliminary comparison of a CC prototype (CLaRyS prototype) and a commercial gamma camera (collimated camera) has been recently performed with promising results for an energy range comprised between 140 and 511 keV.
Objectives of the master internship
The first objective of this internship consists in completing this preliminary study to quantify the gain on Compton cameras in terms of e.g. acquisition time for a given image quality. Then, the student will optimize the design of a Compton camera for an energy range comprised between 140 and 511 keV, with special interest in assessing the ability to estimate the 3D distribution of Technetium-99m (99mTc) which is the most widely used radiotracer for diagnostics. To this end, different geometric configurations such as single-layer and multi-layer systems will be studied based on different detector technologies considering recent advances on instrumentation. In particular, CZT semiconductor detector technology will be investigated within a collaboration with experts in gamma-ray imaging of CEA-LETI that have already developed Compton cameras [Montémont 2016] based on this technology for environmental radiation monitoring.
Tasks of the master internship.
- Finalize the comparison of the CLaRyS CC prototype with a commercial gamma camera
- Model Compton camera prototypes based on recent advances on instrumentation
- Simulate Compton camera acquisitions based on different configurations, single and multi-layer systems
- Compare performance of different detector technologies with simple source distributions
- Evaluate reconstructed image quality with a single and multiple Compton camera prototypes rotating around the subject of study
- Assess the ability of different selected prototypes to image the distribution of 99mTc in a realistic situation
The student will work in a multidisciplinary team composed of researchers in inverse problems, tomography, imaging for radio-therapy and Monte Carlo simulations of CREATIS and IP2I laboratories.
- Medical physics, computer sciences, image processing
- Technical skills: Python is required, experience with GATE would be an asset
[Etxebeste 2020] Etxebeste, A., Dauvergne, D., Fontana, M., Létang, J. M., Llosá, G., Munoz, E., … Sarrut, D. (2020). CCMod: a GATE module for Compton camera imaging simulation. Physics in Medicine and Biology, 65(5), 055004. https://doi.org/10.1088/1361-6560/ab6529
[Maxim 2016] Maxim, V., Lojacono, X., Hilaire, E., Krimmer, J., Testa, E., Dauvergne, D., Magnin I & Prost, R. (2015). Probabilistic models and numerical calculation of system matrix and sensitivity in list-mode MLEM 3D reconstruction of Compton camera images. Physics in Medicine & Biology, 61(1), 243. https://doi.org/10.1088/0031-9155/61/1/243
[Montémont 2016] G. Montémont, O. Monnet, S. Stanchina, M. M. Bernard, Loick Verger. Recent Improvements to HiSPECT Imaging Module. IEEE Nuclear Science Symposium (NSS/MIC'16), Oct 2016, Strasbourg, France. ⟨hal-01445856⟩
[Sarrut 2021] Sarrut D, et al. (2021) Advanced Monte Carlo simulations of emission tomography imaging systems with GATE. Physics in Medicine and Biology, 66(10). doi: 10.1088/1361-6560/abf276
[Tashima 2022] Tashima, H., & Yamaya, T. (2022). Compton imaging for medical applications. Radiological Physics and Technology, 15(3). https://doi.org/10.1007/s12194-022-00666-2