Exploration of simultaneous dual-isotope imaging with multi-photon modular J-PET scanner
Ermias Yitayew Beyene, Manish Das, Martyna Durak-Kozica, Grzegorz Korcyl, Wiktor Mryka, Szymon Niedźwiecki, Szymon Parzych, Keyvan Tayefi Ardebili, Rafał Walczak, Kamil Wawrowicz, Ewa Stępień, Paweł Moskal
abstract
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 2? 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.
Application of an ultra-high dose rate (FLASH) proton beam for the 3D cancer cell model - a proof of concept
M. Durak-Kozica, E. Stępień, J. Swakoń, P. Moskal
abstract
Ultra-high dose rate (FLASH) proton radiotherapy is a promising treatment method for cancer patients. In our research, we want to compare the FLASH method with a conventional radiation method to show what effect they have on the biochemical structure of the tumour (3D model ? spheroids) and the secretion of extracellular vesicles (EVs) and their cargo. The use of a modern method of creating spheroids will enable us to create conditions that are better able to mimic the tumour microenvironment.
Experimental and analytical procedures for the ToF-SIMS measurement data of membranous structures
M. Skalska, M. Durak-Kozica
abstract
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a powerful analytical technique with great application potential in biomolecular matter research. SIMS measurements performed on biological samples, due to their complex structure and the content of many small and large atomic molecular compounds, suffer very rich and complex mass spectra of particles, which characterise the content and physio-chemical properties of examined samples. The proper description and understanding of features appearing in the spectra and, consequently, the final data confirming or rejecting the hypothesis put forward in the experiment, largely depend on the experimenter?s correct understanding of the technique itself and its limitations, knowledge of the tested material and its appropriate preparation. These issues mean that obtaining the right answer to the questions posed in the research hypothesis requires not only the correct conduct of experiments but also the appropriate processing of post-experimental data. This study aims to demonstrate the impact of various analytical and experimental procedures applied to reach proper conclusions from TOF-SIM measurements. These are different types of data normalization, the selection of a so-called region of interest (ROI), the selection of representative secondary ions and specific quantification methods, including a combination of experimental parameters. All these aspects were checked and discussed based on the results of the analysis of pancreatic ? cells placed in a PBS solution on silicon wafers.
Extracellular vesicles in vascular pathophysiology: beyond their molecular content
E.Ł. Stępień, M. Durak-Kozica, P. Moskal
abstract
Extracellular vesicles (EVs) are released by all cells, both in physiological and pathological conditions. Their molecular charge and composition emerge as possible biomarkers, but EVs may also be considered for other clinical applications. This review discusses the role of other features of EVs, such as their lipid components or composition of glycans that form the EV corona and regulate EV biodistribution and uptake by target cells. The importance of EV electric charge has been discussed as a new insight into EV fate and destination.
Comparison of qNANO results from the isolation of extracellular microvesicles with the theoretical model
M. Durak-Kozica, A. Wróbel, M. Platt, E. Stępień
abstract
Objectives: Extracellular vesicles (EVs) are heterogeneous membrane vesicles in diameter of 30-5000 nm, that transport proteins, non-coding RNAs (miRNAs), lipids and metabolites. Major populations include exosomes, ectosomes and apoptotic bodies. The purpose of this study was to compare the distribution of EVs obtained under different conditions of differential centrifugation, including ultracentrifugation, with the results developed based on a theoretical model. Methods: Immortalized endothelial cell line that expresses h-TERT (human telomerase) was used to release of EVs: microvascular TIME. EVs were isolated from the culture medium at different centrifugation parameters. The size distribution of the EVs was measured using TRPS technology on a qNano instrument. Surface markers were evaluated using flow cytometry. The isolated EV subpopulations were compared with the theoretical model developed by Livshits. Results: EVs isolated from endothelial cells show strong aggregating properties, which was confirmed by TEM, TRPS imaging and flow cytometry. Conclusions: Obtaining pure EV subpopulations is difficult because of the small differences in the diameter of ectosomes and exosomes, and the strong aggregating properties of EVs.
