BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Invited talk: A statistical reconstruction algorithm for positroni um lifetime imaging using time-of-flight positron emission tomography DTSTART;VALUE=DATE-TIME:20220711T122000Z DTEND;VALUE=DATE-TIME:20220711T124000Z DTSTAMP;VALUE=DATE-TIME:20261008T195223Z UID:indico-contribution-41-658@indico.koza.if.uj.edu.pl DESCRIPTION:Speakers: Hsin-Hsiung Bill Huang\; University of Central Flor ida\, USA ()\nAs an emerging technology\, positronium lifetime imaging (PL I) using time-of-flight (TOF) positron emission tomography (PET) provides supplemental information reflecting the microenvironment surrounding the t issue\, in addition to the radiotracer activities from PET scan. However\, due to the finite coincidence resolving time (CRT)\, typically on the ord er of 200 – 600 ps\, reconstruction of the lifetime image from PLI list- mode events has yet to be fully developed. \n Previous studies have estab lished the feasibility of positronium lifetime imaging using TOF PET scann ers that have superior CRT to allow precise localization of each event in space [Moskal 2019\, Shibuya 2020]. Currently\, no practical TOF PET scann ers have the needed CRT and therefore the studies consider only well-separ ated sources that can be resolved by systems having a finite CRT. The exis ting positronium imaging method [Qi 2022] considers the marginal likelihoo d of the lifetime parameter given the radiotracer activity parameter and a pplies a surrogate function to estimate the lifetime parameter. In contras t\, our proposed method directly models the lifetime and activity paramete rs and estimates them jointly. Our method overcomes all these challenges a nd produces quantitatively correct lifetime images beyond the resolution l imit of the system CRT.\n We address the problem of reconstructing the li fetime image from TOF PET data with finite CRT. We present a statistical r econstruction framework that maximizes the likelihood of observed PLI even ts\, each comprising the following observable attributes: the detector re ceiving the prompt gamma\, the detector pair receiving the annihilation pa ir\, the time difference between the detection of prompt gamma and annihil ation pair\, and the time difference between the two photons within the an nihilation. In our study\, our simulation data include the flight time of the photons before detection and our method does not require having sub-1 00 ps TOF resolution for accurate localization of each detected event. We have verified our method using PLI events generated by the Monte-Carlo si mulation.\n\nhttps://indico.koza.if.uj.edu.pl/event/7/contributions/658/ LOCATION:Collegium Maius URL:https://indico.koza.if.uj.edu.pl/event/7/contributions/658/ END:VEVENT BEGIN:VEVENT SUMMARY:Current progress\, challenges and frontiers for Ps-based oncology nanodiagnostics DTSTART;VALUE=DATE-TIME:20220711T134000Z DTEND;VALUE=DATE-TIME:20220711T140000Z DTSTAMP;VALUE=DATE-TIME:20261008T195223Z UID:indico-contribution-41-660@indico.koza.if.uj.edu.pl DESCRIPTION:Speakers: Bożena Zgardzińska\; Maria Curie-Sklodowska Univer sity\, Poland ()\nPublication agreement (CC BY 4.0) Yes\nPrimary authors\ nBożena Zgardzińska (Institute of Physics\, Maria Curie-Sklodowska Unive rsity) Dr Jerzy Mielko (Department of Surgical Oncology\, Medical Universi ty of Lublin) Ms Katarzyna Gęca (Department of Surgical Oncology\, Medica l University of Lublin) Marek Gorgol (Maria Curie-Sklodowska University\, Institute of Physics\, Department of Nuclear Methods\, Pl. M. Curie-Sklodo wskiej 1\, 20-031 Lublin\, Poland) Radek Zaleski (Maria Curie-Skłodowska University) Magdalena Goździuk (Maria Curie- Sklodowska University) Boże na Jasińska (Institute of Physics\, Maria Curie Sklodowska University) Dr Stephenson Owusu (Radiation Research Laboratory\, University of Notre Dam e) Dr Gustaw Chołubek (Diagnostic Techniques Unit\, Faculty of Health Sci ences\, Medical University of Lublin) Mr Konrad Wysogląd (Institute of Ph ysics\, Maria Curie-Sklodowska University) Katsiaryna Yankova\nPresentatio n Materials\nThere are no materials yet.\n\nhttps://indico.koza.if.uj.edu. pl/event/7/contributions/660/ LOCATION:Collegium Maius URL:https://indico.koza.if.uj.edu.pl/event/7/contributions/660/ END:VEVENT BEGIN:VEVENT SUMMARY:Study of positronium in normal and cancer cells DTSTART;VALUE=DATE-TIME:20220711T132000Z DTEND;VALUE=DATE-TIME:20220711T134000Z DTSTAMP;VALUE=DATE-TIME:20261008T195223Z UID:indico-contribution-41-659@indico.koza.if.uj.edu.pl DESCRIPTION:Speakers: Ewelina Kubicz-Staszkiewicz\; Jagiellonian Universit y\, Poland ()\nhttps://indico.koza.if.uj.edu.pl/event/7/contributions/659/ LOCATION:Collegium Maius URL:https://indico.koza.if.uj.edu.pl/event/7/contributions/659/ END:VEVENT BEGIN:VEVENT SUMMARY:Multiphoton time-of-flight MLEM reconstruction for the positronium imaging in J-PET DTSTART;VALUE=DATE-TIME:20220711T130000Z DTEND;VALUE=DATE-TIME:20220711T132000Z DTSTAMP;VALUE=DATE-TIME:20261008T195223Z UID:indico-contribution-41-657@indico.koza.if.uj.edu.pl DESCRIPTION:Speakers: Roman Shopa\; National Centre for Nuclear Research\, Poland ()\nWe modify the positronium imaging method for the Jagiellonian PET (J-PET) scanners\, using the simulated data for the decays of a metast able ortho-positronium (o-Ps) based on the pick-off and conversion process es resulting in two 511-keV annihilation photons [1\, 2]. An analytical mo del\, embedded into the time-of-flight maximum likelihood expectation maxi misation (TOF MLEM) reconstruction algorithm\, is introduced for the asses sment of the multiphoton detector response and the estimation of the o-Ps mean lifetime.\nThe detection probabilities of the J-PET system matrix are calculated for the coincident events each constituted by two annihilation and one deexcitation photons. TOF information is used for the iterative M LEM run and the estimation of a time difference between the annihilation a nd the positron emission\, the distribution of which is built for each vox el. The latter is updated in event-by-event way using the weights for the ultimate MLEM iteration.\nEmploying the Geant4 software [3]\, we simulated the experiments with four point-like sources put into two existing J-PET prototypes\, each corresponding to a tissue of a different o-Ps lifetime\, with total activity 1.1 MBq for the injected 22Na [2\, 4]. The decay mode l was restricted to include only the decays into back-to-back photons\, im plying the exponentially modified Gaussian shape for the aforementioned ti me difference histograms.\nUtilising TOF MLEM allowed to reduce the noise and significantly improve the spatial resolution of the positronium imagin g\, compared to the earlier studies [1\, 2]. The o-Ps mean lifetimes\, cal culated as a result of fitting the histograms exhibited a good consistency with the simulation setup. The reconstruction algorithm uses the advanced resolution model that accounts for both the geometrical factors and the d etector blur of the J-PET\, and can as well be extended to include attenua tion correction or other contributions\, as well as for the o-Ps decay int o three photons.\n\n[1] P. Moskal et al. “Performance assessment of the 2γ positronium imaging with the total-body PET scanners\,” EJNMMI Phys. \, vol. 7\, no. 44\, pp. 1\, Jun. 2020.\n[2] P. Moskal et al.\, “Positro nium imaging with the novel multiphoton PET scanner\,” Sci. Adv.\, vol. 7\, no. 42\, pp. 1\, Oct. 2021.\n[3] S. Agostinelli et al.\, “Geant4 – A Simulation Toolkit\,” Nucl. Instrum. Meth. A\, vol. 506\, no. 1\, pp. 250\, Jul. 2003.\n[4] P. Moskal et al.\, “Simulating NEMA characteristi cs of the modular total-body J-PET scanner – an economic total-body PET from plastic scintillators\,” Phys. Med. Biol.\, vol. 66\, no. 17\, pp. 175015\, Sep. 2021.\n\nhttps://indico.koza.if.uj.edu.pl/event/7/contributi ons/657/ LOCATION:Collegium Maius URL:https://indico.koza.if.uj.edu.pl/event/7/contributions/657/ END:VEVENT BEGIN:VEVENT SUMMARY:Invited talk: Positron Annihilation Spectroscopy of oxygen content tissue-equivalent samples DTSTART;VALUE=DATE-TIME:20220711T124000Z DTEND;VALUE=DATE-TIME:20220711T130000Z DTSTAMP;VALUE=DATE-TIME:20261008T195223Z UID:indico-contribution-41-582@indico.koza.if.uj.edu.pl DESCRIPTION:Speakers: Ali Biganeh\; Nuclear Science and Technology Researc h Institute\, Iran ()\nPositron Annihilation Spectroscopy (PAS) has numero us applications in material science such as studies of structural defects\ , free volumes\, porous materials\, and their chemical environments. In re cent years\, the applications of this technique in chemical processes\, ra diobiology\, and medicine have been the subject of research by many resear chers [1\, 2]. PAS includes Coincidence Doppler Broadening Spectroscopy (C DBS) of annihilation radiation to determine the momentum of the electrons involved in the annihilation process and Positron Annihilation Lifetime Sp ectroscopy (PALS) for the investigation of the mechanism behind the positr onium annihilation in the sample. In this paper\, the possible application of the PALS technique for the characterization of healthy and cancer tiss ues is evaluated. The purpose of the experimental part of this work is to investigate the sensitivity of the PALS technique to the oxygen concentrat ion in tissue-equivalent samples.\nThe accepted hypothesis for this resear ch is that the concentration of oxygen in cancer tissues is less than in h ealthy tissues due to the massive cell proliferation [3]. To conduct the e xperiments\, the PALS spectrometer based on digital signal processing has been designed\, commissioned\, and optimized in the NSTRI positron lab. Th is spectrometer makes it possible to record the time difference of events with a channel width of 10 ps and the timing resolution of 173 ps using th e plastic scintillation detectors. To determine the sensitivity of the tec hnique to the presence of the polar groups including carbon-oxygen boundin g\, 4 polymer samples were measured using PALS and CDBS techniques\, and t he correlation between the parameters was clarified. The results of this i nvestigation confirmed that the position and height of the peak in the Orb ital Electron Momentum Spectrum (OEMS) obtained in the Doppler experiment and the component of the positronium lifetime in the PALS technique are bo th sensitive to the presence of oxygen in the content [4]. To determine th e PALS parameters related to the amount of oxygen\, 6 tissue-equivalent po lymers with different concentrations of oxygen were selected. The positron lifetime spectra in these samples were measured using the developed digit al PALS spectrometer and the results were analyzed using LT-10 software. T he results of this experiment confirmed that in general\, as the oxygen co ncentration in the sample increases\, due to the quenching role of oxygen atoms in the formation of the positronium atoms\, the I_3 and τ_3 paramet ers decrease significantly. However\, in the samples with a difference of about 4% in the oxygen concentration\, the behavior analysis of the positr onium lifetime and its intensity requires a systematic study of the effect of density\, porosity\, crystallinity\, and the bond type in the polymer samples. The results of this work apply to the development of a tumor imag ing system based on the PALS technique.\nReferences\n[1] Moskal\, Paweł\, and Ewa Stępień. "Positronium as a biomarker of hypoxia." Bio-Algorithm s and Med-Systems (2021).‏\n[2] Stepanov\, P. S.\, et al. "Interaction o f positronium with dissolved oxygen in liquids." Physical Chemistry Chemic al Physics 22.9 (2020): 5123-5131.‏\n[3] Brahimi-Horn\, M. Christiane\, Johanna Chiche\, and Jacques Pouysségur. "Hypoxia and cancer." Journal of molecular medicine 85.12 (2007): 1301-1307.‏\n[4] Zare\, Mahshid\, et a l. "Experimental investigation of the oxygen sensing ability of positron a nnihilation spectroscopy for tumor imaging." Radiation Physics and Enginee ring (2022).‏\n\nhttps://indico.koza.if.uj.edu.pl/event/7/contributions/ 582/ LOCATION:Collegium Maius URL:https://indico.koza.if.uj.edu.pl/event/7/contributions/582/ END:VEVENT BEGIN:VEVENT SUMMARY:First clinical positronium imaging of patients DTSTART;VALUE=DATE-TIME:20220711T120000Z DTEND;VALUE=DATE-TIME:20220711T122000Z DTSTAMP;VALUE=DATE-TIME:20261008T195223Z UID:indico-contribution-41-581@indico.koza.if.uj.edu.pl DESCRIPTION:Speakers: Pawel Moskal\; Jagiellonian University\, Poland ()\n https://indico.koza.if.uj.edu.pl/event/7/contributions/581/ LOCATION:Collegium Maius URL:https://indico.koza.if.uj.edu.pl/event/7/contributions/581/ END:VEVENT END:VCALENDAR