Conveners
Technologies for ≤100ps TOFPET resolution: Scintillators
- Paul Rene Michel Lecoq
Technologies for ≤100ps TOFPET resolution: Scintillators
- Etiennette Auffray Hillemanns (CERN)
Technologies for ≤100ps TOFPET resolution: Scintillators
- Rosana Martinez Turtos (Aarhus University (DK))
Technologies for ≤100ps TOFPET resolution: Scintillators
- Paul Rene Michel Lecoq
Nanophotonics - the control of the flow of light on the nanoscale - had immense impact on technology in recent years, with example spanning from solar cells and LEDs to the telecommunication industry.
We will discuss the prospects of nanophotonics for the development of future scintillators.
In particular, I will focus on two recent experiments:
1. At MIT, we observed a ten-fold...
Since many decades scintillating crystals have been used for radiation detectors such as high resolution electromagnetic calorimeters and positron emission tomographs. Significant progress has been made in the field of inorganic scintillators in the understanding of their scintillation properties, radiation hardness and production methods over the last 30 years. In addition many applications...
Ultrafast emission processes are required to further improve the coincidence time resolution (CTR) of time-of-flight PET detectors. Extensive research efforts are underway in trying to generate and detect so-called prompt photons having much faster emission dynamics than conventional scintillation. In this contribution, we provide an analysis on key aspects to better model and understand the...
Time-of-flight positron emission tomography (TOFPET) is currently one of the key directions in medical imaging enabling substantially higher spatial resolution and lower radiation dose for patients. This trend requires new scintillators with faster response and currently results in the substitution of BGO by LYSO:Ce as the scintillator of choice in TOFPETs. The scintillator material represents...
In this contribution we extend the current understanding of the different energy-transfer mechanisms present in state-of-the-art Lu(2−x)YxSi2O5:Ce scintillators. We present results of a photon emission mechanism known as optical stimulated luminescence (OSL), able to efficiently trap a fraction of the energy deposited in the material. OSL competes with the non-radiative energy transfer to...
A semi-monolithic scintillator crystal consists of a monolithic block segmented in only one direction in different pieces called slabs. This approach is intended to combine the benefits of both pixelated and monolithic crystals, which are usually employed in PET detectors, preserving the good timing resolution of pixelated crystals, and the high sensitivity and good spatial resolution of...
Purpose– The coincidence time resolution (CTR) values can be improved by increasing photostatistics, which in the PET detector occurs with a high light yield (LY) of scintillation crystals. The two main contributors to the LY are the intrinsic LY of the scintillation crystal and the light transfer efficiency, which depend on crystal material, dimensions, and wrapping conditions. We report on a...
Scintillating materials suffer degradation while in operation due to defects induced in the process. Lattice defects could severely impact detector efficiency via non-radiative transfer of electron excitation. Like most materials for this kind of applications, there is a strong performance-structure relationship. An understanding of the defect formation process is therefore important in the...
— In order to achieve superior timing for time-of-flight positron emission tomography, combined with high detection efficiency and cost-effectiveness, we probe the applicability of BaF2 in metascintillators driven by timing of cross-luminescence photon production. Building on simulation study of energy sharing and analytic multi-exponential scintillation pulse and sensitivity characteristics,...
There is a desire to continue reducing the time resolution of scintillator based detectors without sacrificing the space resolution to further improve the image resolution of current ToF PET scanners. Unfortunately, we have reached a limit of finding one ideal single crystal candidate that can achieve both aims. Current commercial LSO and LYSO crystal detector can offer time resolution...
In the field of time-of-flight positron emission tomography (PET-TOF), the time resolution of the scintillationbased detector is an essential feature. Recent studies have shown that some materials have fast emissions in the vacuum ultraviolet (VUV) region.
To acquire the fast-rising signals of these emissions, we are using optimized Coincidence Time Resolution (CTR) test boards with two...
The novel concept of metascintllator, topologies consisting of heterogeneous scinitllating and light-guiding materials has been proved to achieve an equivalent CTR of 200ps for BGO-based set and 140ps for LYSO-based set even with an non-optimized configuration. In this work, we evaluate a novel architecture: The principle is to slice a slow scintillator (BGO or LYSO) monolithic in thin slabs,...
Lutetium-based scintillators (LSO, LYSO, LGSO) are commonly used for TOF-PET, representing the better compromise between stopping power, light yield, energy and time resolution. However, the limit in the improvement of time performances of these materials has been reached, and new technologies to break the current boundaries are being investigated. Heterostructured scintillators are gaining...
In recent years the need for ultrafast detection of ionizing radiation is being pushed particularly by high energy physics and medical imaging. It requires detection systems involving scintillating materials able to produce quasiprompt photons. To achieve that, there are several concepts currently being pursued, one of them being exploitation of quantum confinement effect in nanoparticles....
Radiation detection is of outmost importance in fundamental scientific research and applications including medical diagnostics, homeland security, environmental monitoring, and non-destructive inspection in industrial manufacturing. Lead halide perovskites (LHP) are rapidly emerging as high-Z materials for next generation of solution processable scintillators and photoconductors for ionizing...
Nanocrystals like ZnO:Ga or CsPbBr$_3$ were identified as potential scintillators for fast timing applications, including medical imaging techniques such as TOF-PET (time-of-flight positron emission tomography) or TOF-CT (time-of-flight computed tomography). Both feature sub-nanosecond scintillation decays which is a crucial property for this type of application.
However, such materials with...
In the quest for optimized time-of-flight scintillation detectors, an important physical barrier is the statistical variation of photon production, propagation, extraction and detection. While nothing can be done for the isotropic production of scintillation light, we simulate a way to alter propagation and extraction of optical photons from the scintillator, using photonic crystal (PhC) slabs...
II-VI semiconductor nanocrystals (NCs) are known to show very good optical fluorescence quantum yields. As direct band gap semiconductors they also exhibit a fast excitonic emission in the order of a few tens of ns. In addition, because of their reduced size, multiple excitation generation are favoured, resulting in a significantly faster emission which can be attractive for the scintillation...
Colloidal nanocrystals combine the flexibility of solution-processed materials with the enhanced stability of inorganic semiconductors. They are typically composed of heavy-metal chalcogenides and have a high fluorescence quantum efficiency, which makes them suitable for the detection of high-energy photons and subsequent conversion into visible radiation.
In this presentation, I will...
To improve timing coincidence resolution to the time scale of few tens of picoseconds in future generations of TOF-PET, among others, scintillator material producing more light in subnanosecond time scale is needed. Semiconductors with Wannier exciton emission in quantum confinement regime are an option as their radiative lifetimes can be shortened down to subnanosecond time scale thanks to...
