The modular J-PET scanner, comprising 24 compact and versatile modules, each consisting of 13 plastic strips with four SiPM detectors at the ends, represents a powerful tool for clinical applications in nuclear medical imaging. This study presents preliminary results from the exploration of simultaneous dual-isotope imaging using the modular J-PET system. Our approach involved two isotopes: 68Ge, characterized by a ringlike shape, and 22Na, exhibiting a point-like shape. The imaging was based on double-coincidence and triple-coincidence events. In the double coincidence case, both isotopes contributed comparably, whereas in the triple coincidence case 22Na dominated due to the prompt gamma being emitted with 100% of positron emissions, unlike 68Ga, where the prompt gamma was emitted in only 1.3% of cases after positron emission. In this work we present direct 2γ images determined for two-signal events and images for three-signal events, with two signals from annihilation photons and one from a prompt gamma. These results showcase the preliminary findings from simultaneous dual-isotope imaging of 68Ga and 22Na isotopes using the modular J-PET scanner, which will be presented and discussed.

Objective: Positron emission tomography (PET) is a widely used medical imaging technique that allows for non-invasive imaging of metabolic processes. However, traditional PET scanners rely on costly inorganic scintillators that limit their accessibility, especially in light of emerging long axial field-of-view devices. The modular J-PET scanner, an innovative alternative, uses 50-cm-long plastic scintillator strips, offering a cost-effective and modular solution. In this study we develop and assess the PET data correction techniques required for quantitative image reconstruction. Methods: We present methods for attenuation correction, random coincidence correction using the delayed time window (DTW) technique and scatter correction based on Monte Carlo simulations. Phantom studies using the NEMA IQ phantom were performed to qualitatively evaluate these corrections. Results: The results demonstrate that our implemented corrections for attenuation and random and scattered coincidences successfully improve the uniformity of tracer distribution in homogenous volumes and significantly reduce undesired activity in cold regions. Despite limitations in sensitivity and axial resolution, the applied correction techniques effectively enhance image quality, providing promising results for future applications. Conclusions: These findings highlight the potential of the modular J-PET system to offer affordable PET imaging and to pave the way for a total-body PET scanner based on plastic scintillators. Future work will focus on quantitative validation and the implementation of these corrections for human subject imaging.

The application of PET scanners to proton-beam-therapy monitoring is a promising solution to obtain the range of the beam and hence the positions of a Bragg peak – maximum dose deposition point. A proton beam induces nuclear reactions in the tissue, leading to the production of isotopes that emit β+ radiation. This enables the imaging of the density distribution of β+ isotopes produced in the body, allowing the reconstruction of the proton beam range. Moreover, PET detectors may open the possibility for in-beam monitoring, which would offer an opportunity to verify the range during irradiation. PET detectors may also allow positronium imaging, which would be the indicator of the tissue conditions. However, the image of annihilation points does not represent the range of the proton beam. There are several factors influencing the translation from annihilation points to obtain the Bragg peak position. One of them is the kinetic energy of the positron. This energy corresponds to some range of the positron within the tissue. In this manuscript we estimate positron energy and its range and discuss its influence on proton therapy monitoring.

The $\mathsf{\mu }$PPET [mu($\mathsf{\mu }$)on Probe with J-PET] project aims to investigate the “Muon Puzzle” seen in cosmic ray air showers. This puzzle arises from the observation of a significantly larger number of muons on Earth’s surface than that predicted by the current theoretical models. The investigated hypothesis is based on recently observed asymmetries in the parameters for the strong interaction cross-section and trajectory of an outgoing particle due to projectile–target polarization. The measurements require detailed information about muons at the ground level, including their track and charge distributions. To achieve this, the two PET scanners developed at the Jagiellonian University in Krakow (Poland), the J-PET detectors, will be employed, taking advantage of their well-known resolution and convenient location for detecting muons that reach long depths in the atmosphere. One station will be used as a muon tracker, while the second will reconstruct the core of the air shower. In parallel, the existing hadronic interaction models will be modified and fine-tuned based on the experimental results. In this work, we present the conceptualization and preliminary designs of $\mathsf{\mu }$PPET.