Speaker
D. Schaart, TUDelft
Description
There remains huge untapped potential for PET in the research, diagnosis and treatment of oncological, neurological, cardiovascular, infectious, and inflammatory diseases. However, to transform PET into a cost-effective tool for personalized medicine in a wide range of clinical applications, we must reduce the radiation dose (currently 5-25 mSv), scan time (currently > 10 minutes), and costs per patient (currently > 1000 €), all by an order of magnitude, as well as improve the compatibility with other modalities to enable multi-parametric data acquisition. Technologically, this translates into a need for more than 10-fold increased sensitivity, without sacrificing other crucial system parameters such as spatial and energy resolution.
In the US, the $15.5 million Explorer project aims at the world’s first total-body PET/CT scanner with a 2 m long axial length, to demonstrate the clinical value of a ~40-fold improved system sensitivity. While major scientific breakthrough are expected from this project, the system concept is intrinsically expensive as it is based on multiplication of existing detector technology.
A different way to improve effective sensitivity is to push time-of-flight (TOF) resolution to less than ~100 picoseconds, ultimately to ~10 ps. Results achieved by European researchers in recent years make it likely that high-resolution TOF-PET imaging with sub-100 ps time resolution can be demonstrated within the coming years [1-3]. In particular, the so-called monolithic scintillator concept shows how timing information can be extracted optimally from the spatio-temporal distribution of the optical signal produced upon the interaction of a gamma photon inside a transparent material [4,5].
Sub-150 ps timing in combination with near-1 mm spatial resolution has already been demonstrated in a simple, scalable, and cost-effective monolithic scintillator detector based on the widely available scintillator LYSO:Ce and digital silicon photomultipliers. Experimental evidence of the clinical imaging performance of this detector as well as further steps towards sub-100 ps clinical TOF-PET imaging will be discussed at the conference.
**References**
[1] DR Schaart et al, LaBr3:Ce and SiPMs for time-of-flight PET: achieving 100 ps coincidence resolving time, Phys Med Biol 55 (2010) N179
[2] S Seifert et al, A Comprehensive Model to Predict the Timing Resolution of SiPM-Based Scintillation Detectors: Theory and Experimental Validation, Ieee T Nucl Sci 59 (2012) 190
[3] MV Nemallapudi, S Gundacker, P Lecoq, E Auffray, A Ferri, A Gola, C Piemonte, Sub-100 ps coincidence time resolution for positron emission tomography with LSO:Ce codoped with Ca, Phys Med Biol 60 (2015) 4635
[4] S Seifert, G van der Lei, HT van Dam, DR Schaart, First characterization of a digital SiPM based time-of-flight PET detector with 1 mm spatial resolution, Phys Med Biol 58 (2013) 3061
[5] HT van Dam, G Borghi, S Seifert, DR Schaart, Sub-200 ps CRT in monolithic scintillator PET detectors using digital SiPM arrays and maximum likelihood interaction time estimation, Phys Med Biol 58 (2013) 3243
