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2026-01-22
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Can tissue oxygenation be sensed by positronium?

Developing a method for non-invasive assessment of hypoxia (oxygen deficiency in tissues) is one of the major challenges in medical imaging. This project is motivated by the exciting question of whether it is possible to assess the level of oxygen concentration in tissues by measuring photons from positronium annihilation inside cells. The exotic positronium atom (a bound state of an electron and a positron) is produced in the human body during diagnosis performed by positron emission tomography (PET). This phenomenon has not been used in medicine until now.

Project description

Developing a non-invasive method for assessing hypoxia (oxygen deficiency in tissues) is one of the major challenges in medical imaging. This project is motivated by the exciting question of whether it is possible to assess oxygen concentration in tissues by measuring photons from positronium annihilation inside cells. The exotic positronium atom (a bound state of an electron and a positron) is produced in the human body during positron emission tomography (PET) diagnostics. This phenomenon has not been used in medicine until now. Only last year, under the direction of Prof. Moskal, the first image of positronium properties in the human brain was obtained. This is a pioneering achievement introducing the use of positronium in medicine. The properties of positronium atoms in tissues depend on the size of the intracellular spaces and the concentration of oxygen molecules. Therefore, theoretically, the positronium atom can serve as a biomarker for tissue oxygenation. But is this really the case? Can positronium annihilation after its interaction with oxygen be distinguished from annihilation with electrons from atoms forming the tissue? There is no a priori answer to this question because the number of classical measurable features available from the measurement of annihilation photons is smaller than the number of mechanisms leading to positron annihilation in tissues. This project proposes a fundamentally new hypothesis that tissue oxygenation can be studied by measuring the degree of entanglement of photons resulting from positronium annihilation. Theoretically, photons resulting from positronium annihilation are quantum entangled in polarization and exhibit non-local correlations - inexplicable classically. Quantum entanglement is reflected in the distribution of the relative angle between the polarization planes of the photons (the polarization planes are schematically shown in the picture below). This project hypothesizes that such distributions are sensitive to tissue hypoxia. This leads to the expectation that the degree of entanglement of photons from positronium interacting with dissolved oxygen differs from the case when annihilation occurs by capturing an electron from a molecule forming the tissue. The research planned in this project will provide the first answers to these fundamental questions. The project will be carried out using the unique J-PET tomographic system and the quantum entanglement measurement method invented by Prof. Paweł Moskal. The J-PET tomograph allows imaging of positronium lifetime in humans and detection of polarization of photons from positronium annihilation. To study entanglement, it is necessary to measure many photons simultaneously. The J-PET tomograph built at the Jagiellonian University under the direction of Prof. Moskal is the first multi-photon tomograph in the world. Therefore, the research planned in this project can currently only be conducted at the Jagiellonian University. No other tomograph offers such possibilities.

Quantum entanglement is a fascinating phenomenon that cannot be explained within our classical perception of the world. Quantum entangled photons behave as if one immediately knew what was happening with the other, regardless of how far apart they are. This project will investigate whether quantum entanglement can be used to study tissue oxygenation. If it turns out that it can, we will be one step closer to non-invasive malignancy assessment of tumors based on tomographic images taken with the J-PET scanner.

prototype of the J-PET tomograph
The photo shows a laboratory prototype of the J-PET tomograph with an overlaid diagram showing the annihilation of an electron with a positron and photons with their polarization planes. The J-PET tomograph built at the Faculty of Physics, Astronomy, and Applied Computer Science of the Jagiellonian University is the world's first positron emission tomography device that operates based on plastic detectors. The Jagiellonian PET (J-PET) opens new diagnostic possibilities. J-PET allows not only imaging of the metabolism of selected substances but also the study of positronium atom properties built from an electron and an anti-electron, which are produced in humans in the spaces between atoms during PET diagnostics. The first positronium image in the world was taken with the J-PET tomograph and published in the journal Science Advances 10 (2024) eadp2840.

History of preparations for the ERC project research and future research perspectives

The outline and concept of the research project aimed at studying the quantum entanglement of annihilation photons were described by Prof. Moskal in 2016 in an article published in the journal Acta Physica Polonica B 47 (2016) 509. In 2018, in an article published in the journal European  Physical  Journal  C 78 (2018) 970, Prof. Moskal and the J-PET team, based on computer simulations, demonstrated that the quantum entanglement of annihilation photons can be studied with the J-PET tomograph based on the measurement of the angle distribution between the polarization planes of photons resulting from positronium annihilation produced inside the J-PET tomograph. In 2021, the first three-photon image confirming the possibility of multi-photon imaging with the J-PET tomograph was published in the journal Nature Communications 12 (2021) 5658. In 2024, the results of the first experiment using the ability to determine the polarization plane of annihilation photons with the J-PET tomograph were published in the journal Nature Communications 15 (2024) 78. And this year, the discovery that photons from matter-antimatter annihilation in material are not completely quantum entangled was described in the journal Science Advances 11 (2025) eads3046. This discovery gives hope that the ERC project will succeed. The basic research conducted within the ERC project will form the scientific basis for future clinical research at the developing Center for Theranostics at the Jagiellonian University. Below is a schematic cross-section of the whole-body J-PET tomograph - the world's first quantum PET tomograph being constructed at the Jagiellonian University.

examples of electron-positron annihilation
The diagram shows the patient and several examples of electron-positron annihilation, whose imaging is currently only possible with the Jagiellonian tomograph, making it a unique research device in the world.