J-PET analysis framework for the prototype TOF-PET detector

Novel TOF-PET scanner solutions demand, apart from the state of the art detectors, software for fast processing of the gathered data, monitoring of the whole scanner and reconstruction of the PET image. In this article we present an analysis framework for the novel STRIP-PET scanner developed by the J-PET collaboration in the Institute of Physics of the Jagiellonian University. This software is based on the ROOT package used in many particle physics experiments.Comment: 4 pages, 2 figure

Sensitivity of discrete symmetry tests in the positronium system with the J-PET detector

Study of certain angular correlations in the three-photon annihilations of the triplet state of positronium, the electron–positron bound state, may be used as a probe of potential CP and CPT-violating effects in the leptonic sector. We present the perspectives of CP and CPT tests using this process recorded with a novel detection system for photons in the positron annihilation energy range, the Jagiellonian Positron Emission Tomography (J-PET). We demonstrate the capability of this system to register three-photon annihilations with an unprecedented range of kinematical configurations and to measure the CPT-odd correlation between positronium spin and annihilation plane orientation with a precision improved by at least an order of magnitude with respect to present results. We also discuss the means to control and reduce detector asymmetries in order to allow J-PET to set the first measurement of the correlation between positronium spin and momentum of the most energetic annihilation photon which has never been studied to dat

Time of flight measurements based on FPGA using a breast dedicated PET

In this work the implementation of a Time-to-Digital Converter (TDC) using a Nutt delay line FPGA-based and applied on a Positron Emission Tomography (PET) device is going to be presented in order to check the system’s suitability for Time of Flight (TOF) measurements. In recent years, FPGAs have shown great advantages for precise time measurements in PET. The architecture employed for these measurements is described in detail. The system developed was tested on a dedicated breast PET prototype, composed of LYSO crystals and Positive Sensitive Photomultipliers (PSPMTs). Two distinct experiments were carried out for this purpose. In the first test, system linearity was evaluated in order to calibrate the time measurements, providing a linearity error of less than 2% and an average time resolution of 1.4 ns FWHM. The second set of measurements tested system resolution, resulting in a FWHM as good as 1.35 ns. The results suggest that the coincidence window for the current PET can be reduced in order to minimize the random events and thus, achieve better image qualityAguilar, A.; García Olcina, R.; Martos, J.; Soret, J.; Torres-Pais, J.; Benlloch Baviera, JM.; González Martínez, AJ.... (2014). Time of flight measurements based on FPGA using a breast dedicated PET. Journal of Instrumentation. 9:0-8. doi:10.1088/1748-0221/9/05/C05012S08

Database and data structure for the novel TOF-PET detector developed for J-PET project

The complexity of the hardware and the amount of data collected during the PET imaging process require application of modern methods of efficient data organization and processing. In this article we will discuss the data structures and the flow of collected data from the novel TOF-PET medical scanner which is being developed at the Jagiellonian University. The developed data format reflects: registration process of the gamma quanta emitted from positron-electron annihilation, Front-End Electronic (FEE) structure and required input information for the image reconstruction. In addition, the system database fulfills possible demands of the evolving J-PET project.Comment: 6 p, 3 figs, based on talk given at Symposium on Positron Emission Tomography, Sept. 19-22, 2013, Jagiellonian University, Krak\'ow PL, submitted to Bio-Algorithms and Med-System

Trilateration-based reconstruction of ortho-positronium decays into three photons with the J-PET detector

This work reports on a new reconstruction algorithm allowing to reconstruct the decays of ortho-positronium atoms into three photons using the places and times of photons recorded in the detector. The method is based on trilateration and allows for a simultaneous reconstruction of both location and time of the decay. Results of resolution tests of the new reconstruction in the J-PET detector based on Monte Carlo simulations are presented, which yield a spatial resolution at the level of 2 cm (FWHM) for X and Y and at the level of 1 cm (FWHM) for Z available with the present resolution of J-PET after application of a kinematic fit. Prospects of employment of this method for studying angular correlations of photons in decays of polarized ortho-positronia for the needs of tests of CP and CPT discrete symmetries are also discussed. The new reconstruction method allows for discrimination of background from random three-photon coincidences as well as for application of a novel method for determination of the linear polarization of ortho-positronium atoms, which is also introduced in this work.Comment: 18 pages, 5 figures. Accepted for publication in Nuclear Instrumentation and Methods in Physics Research

Time resolution of the plastic scintillator strips with matrix photomultiplier readout for J-PET tomograph

Recent tests of a single module of the Jagiellonian Positron Emission Tomography system (J-PET) consisting of 30 cm long plastic scintillator strips have proven its applicability for the detection of annihilation quanta (0.511 MeV) with a coincidence resolving time (CRT) of 0.266 ns. The achieved resolution is almost by a factor of two better with respect to the current TOF-PET detectors and it can still be improved since, as it is shown in this article, the intrinsic limit of time resolution for the determination of time of the interaction of 0.511 MeV gamma quanta in plastic scintillators is much lower. As the major point of the article, a method allowing to record timestamps of several photons, at two ends of the scintillator strip, by means of matrix of silicon photomultipliers (SiPM) is introduced. As a result of simulations, conducted with the number of SiPM varying from 4 to 42, it is shown that the improvement of timing resolution saturates with the growing number of photomultipliers, and that the 2 x 5 configuration at two ends allowing to read twenty timestamps, constitutes an optimal solution. The conducted simulations accounted for the emission time distribution, photon transport and absorption inside the scintillator, as well as quantum efficiency and transit time spread of photosensors, and were checked based on the experimental results. Application of the 2 x 5 matrix of SiPM allows for achieving the coincidence resolving time in positron emission tomography of $\approx$ 0.170 ns for 15 cm axial field-of-view (AFOV) and $\approx$ 0.365 ns for 100 cm AFOV. The results open perspectives for construction of a cost-effective TOF-PET scanner with significantly better TOF resolution and larger AFOV with respect to the current TOF-PET modalities.Comment: To be published in Phys. Med. Biol. (26 pages, 17 figures