A novel TOF-PET detector based on plastic scintillators

The Jagiellonian-PET (J-PET) collaboration is developing a novel TOF-PET tomography scanner based mainly on the timing of signals instead of their amplitudes for the reconstruction of Lines-of-Response, therefore a very precise time resolution is one of the main challenges of the project. The novelty of the concept lies in employing long strips of plastic scintillators instead of crystals as detectors of the annihilation quanta. The diagnostic chamber consists of plastic scintillator strips readout by pairs of photomultipliers arranged axially around a cylindrical surface. To take advantage of the superior timing properties of plastic scintillators, the signals are sampled in the voltage domain with an accuracy of 20 ps by novel ultra-fast electronics, and the data are collected by the FPGA-based trigger-less data acquisition system. The hit-position and hit-time are reconstructed by the dedicated reconstruction methods based on the compressing sensing theory and a library of synchronized model signals. The solutions are subject of sixteen patent applications. So far, a time-of-flight resolution of 125 ps (σ) was achieved for a double-strip prototype with 30 cm field-of-view (FOV). It is by more than a factor of two better than the TOF resolution achievable in current TOF-PET modalities and at the same time, the FOV of 30 cm long prototype is significantly larger with respect to typical commercial PET devices. The axial geometry gives unique possibilities of combining J-PET with Computed Tomography or with Magnetic Resonance Imaging, allowing to perform the simultaneous scan of the patient with both methods.