SPADnet aims to develop a new generation of smart, large area networked image sensors, based on a conventional CMOS fabrication technology (the same as used for microchips or sensors in cellphone cameras, for example), for photon-starved biomedical applications*. SPADnet will build ring-assembly modules for Positron Emission Tomography (PET) medical imaging, and carry out performance tests in a PET system evaluation testbed.
Envisioned PET ring
SPADnet’s prime objective is to develop a scalable photonic component for large format, rare-event imaging. The core of the component will be an array of SPADs (Single-Photon Avalanche Diodes, very sensitive light detectors, capable of detecting and timing a single quantum of light), implemented in a conventional CMOS technology. This will enable the integration in a mainstream technology, capable of volume production, of the single-photon sensing part as well as the related electronics, rather than having to use dedicated fabrication processes. Furthermore, the sensors will be faster and cheaper than existing devices, and compatible with the use in strong magnetic fields, a prerequisite for the integration of PET scanners with MRI machines (a current industry trend).
Single-Photon Avalanche Diode technology
In SPADnet we push the limits of many technologies necessary for the success of the project. The multidisciplinary effort will yield new and highly miniaturized detectors, ultra-fast integrated electronics, high-precision quantitative bioimaging systems, miniaturized optical components, and new signal processing solutions. The consortium we assembled represents Europe's leading Institutions in these fields and decades of experience in industrial and research sensor design and optics.
Just as the MEGAFRAME project (http://www.megaframe.eu/) helped establish European excellence in photon imaging and, we believe, helped inspire new products in the European biomedical imaging industry, we think that SPADnet will help Europe advance firmly in the field of photon-starved imaging and take the lead in new developments in medical, bio- and neuroscience, and other industrial fields that are currently in a period of renewing and growth.
*Photon-starved regime means a regime of extremely low illumination, such as in many medical imaging systems, in particular those using radiotracers ("ordinary" X-ray imaging, including CT imaging, is not necessarily photon starved per se, but might still profit from the proposed developments). In these regimes rare, single (light) bursts are the norm rather than the exception. In the case of PET, the proposed developments will potentially enable better quality images with lower doses of radiotracers. Incidentally, other biophotonic and biomedical applications are also photon starved (e.g. those based on fluorescence lifetime imaging, which can also be tackled by the proposed sensor), and the same is true of applications in areas such as astronomy or particle physics.