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We present results of simulations on the influence of photon propagation and the Cherenkov effect on the time resolution of LSO:Ce scintillators. The influence of the scintillator length on the coincidence time resolution is shown. Furthermore, the impact of the depth of interaction on the time resolution, the light output and the arrival time distribution at the photon detector is simulated and it is shown how these information can be used for time walk correction.
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In this contribution we present a new concept of the large acceptance detector systems based on organic scintillators which may allow for simultaneous diagnostic of large fraction of the human body. Novelty of the concept lies in employing large blocks of polymer scintillators instead of crystals as detectors of annihilation quanta, and in using predominantly the timing of signals instead of their amplitudes.
The aim of this work is to show the potential capabilities of monolithic crystals coupled to large SiPM arrays, to be considered as detector blocks for PET scanners enabling Time Of Flight (TOF) capabilities. Monolithic blocks allow one to decode the 3D photon impact position. This approach, along with TOF information, can be of high interest in clinical Positron emission tomography (PET) applications where a typical ring configuration is used. In this manuscript, we evaluate an ASIC- based readout for digitizing all signals coming from analog photosensors. Validation results with one-to-one coupling resulted in a Coincidence Time Resolution (CTR) of 202 ps FWHM. Providing timing resolution when using detectors based on monolithic crystals is however challenging. The wide distribution of scintillation light on the photosensors causes a poor SNR, which makes the system sensible to false triggering and to time walk errors. In this direction, we present a calibration method, designed to correct all recorded timestamps and also to compensate variations in time-paths among all channels. Thereafter, a CTR improvement nearing 45% is observed for all measurements. Moreover, we show a novel approach that describes the use of averaging methods to assign a single timestamp to each gamma impact. This approach results in a further improvement of the CTR in the range of 100 ps FWHM, reaching a time resolution of 585 ps FWHM when using a large 50x50x10 mm3 LYSO scintillator coupled to an 8x8 SiPM (6x6 mm2) array. These pilot studies show detector capabilities regarding TOF information when using monolithic scintillators.
The Jagiellonian Positron Emission Tomograph (J-PET) is the first PET built from plastic scintillators. J-PET prototype consists of 192 detection modules arranged axially in three layers forming a cylindrical diagnostic chamber with the inner diameter of 85 cm and the axial field-of-view of 50 cm. An axial arrangement of long strips of plastic scintillators, their small light attenuation, superior timing properties, and relative ease of the increase of the axial field-of-view opens promising perspectives for the cost effective construction of the whole-body PET scanner, as well as construction of MR and CT compatible PET inserts. Present status of the development of the J-PET tomograph will be presented and discussed.
Pixelated PET systems produce higher count rates as they integrate several detecting channels per detector module. An increased data flow from the detectors posses higher needs on the bandwidth requirements. We aim to optimize the bandwidth usage efficiency by filtering on the fly the detected events with non valid energies. PET systems with a SiPM-ASIC readout scheme are being extensively used to get enhanced images on Time-Of-Flight PET scanners. These kind of digital readout systems are specially interesting for the application of on-line processing techniques given the ease of access to each detected event digital information. This study purses the analysis of on-line processing techniques on the DAQ front-end level (on-detector electronics) for pixelated PET systems with SiPM-ASIC readout. In particular, we worked with a tunable on-line energy discriminating stage. For the optimization of its hardwired internal limits we analyzed the system energy space. We explored different solutions dependent or not on the systems energy calibration. Results obtained through the different filt
The upgrade of the current BESIII Endcap TOF (ETOF) is carried out with the Multi-gap Resistive Plate Chamber (MRPC) technology. The installation of the new ETOF has been finished in October 2015. The first results of the MRPCs commissioning at BESIII are reported in this paper.
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