Research Projects

Positron Emission Tomography (PET) is a non-invasive imaging modality crucial for early cancer detection, neurological diagnostics, and cardiovascular research. The emergence of Time-of-Flight PET (ToF-PET) has significantly improved image signal-to-noise ratio by using the arrival time difference between coincident annihilation photons. However, even the best commercial scanners today operate with Coincidence Time Resolution (CTR) between 210–400 ps, primarily limited by the intrinsic properties of current scintillators like LSO (ρ = 7.4 g/cm3; τ = 40 ns) and their inability to simultaneously achieve fast timing and high stopping power. Also, current detector architectures are limited to planar geometries composed of mechanically stacked components, which restricts design flexibility. There is a pressing need for next-generation detector modules that combine ultrafast timing, high stopping power, and scalable manufacturing to push the boundaries of PET performance. In addition, improved ToF detectors can be extremely helpful in ToF Particle Identification, n-γ ToF Spectroscopy, security screening, non-destructive testing, etc. Scientific Objectives: This project aims to overcome these fundamental bottlenecks by engineering novel hetero-structured scintillators using a combination of transparent ceramics and fast plastic scintillators fabricated via 3D printing. The broad scientific objectives of the proposal are given below: • To develop hetero-structured scintillator modules that synergistically combine dense ceramics and plastic scintillators. • To achieve a target CTR of ≤100 ps, at least a two- to four-fold improvement over current commercial ToF-PET systems. • To optimize module geometry and composition to maximize both timing performance and gamma detection efficiency. • To demonstrate scalable, indigenous fabrication, supporting the “Make in India” initiative for medical technology. The central hypothesis is that a hetero-structured scintillator, integrating a thin and fast-response plastic layer with a high-density ceramic, can simultaneously deliver ultrafast timing and high gamma-ray stopping power. This architecture is expected to enable CTR values ≤100 ps without significant loss of sensitivity, outperforming monolithic scintillators. Main Experiments: • Growth and polishing of single crystals using a vertical Bridgman setup. • Formulation and 3D-printing of pristine/nanocomposite plastics and ceramics green bodies. • De-binding and sintering of ceramic structures using vacuum-assisted furnaces. • Assembly of heterostructures with different configurations (layered, embedded, or fiber-type). • Optical and scintillation characterization using γ-sources, SiPMs, and digitizers. • Post-irradiation performance monitoring using gamma irradiation chamber and neutron sources. Significance and Impact: If successful, this work will be the first heterostructure scintillator combining all-3D-printed components globally, offering customizable detector blocks that can significantly outperform traditional designs in CTR, spatial resolution, and modularity. The project will have the potential to achieve the following: • Set a new benchmark for ToF detector timing, achieving spatial localization uncertainty of ~15 mm (CTR 100 ps) versus ~60 mm in current systems, with future potential to reach 11 mm (CTR 75 ps). • Enable PET imaging with superior lesion detectability, contrast, and quantitative accuracy, potentially allowing for lower patient dose and faster scans. • Deepen fundamental understanding of scintillation processes in hybrid materials and their integration via additive manufacturing. • Establish a scalable, indigenous technology platform for advanced ToF-PET and other ToF detectors, reducing reliance on imports and fostering domestic innovation. • Provide a blueprint for retrofitting or upgrading existing simple PET systems, with the possibility of enabling ToF capabilities through detector and electronics upgrades.