Calibration of PALS System with CRM Materials for Biomedical Studies
K. Kubat, Ł. Kapłon, P. Moskal, E. Stępień
abstract
Objective and method: Positron annihilation lifetime spectroscopy (PALS) is a powerful technique in material science that allows the investigation of the properties and behavior of positrons in various materials. PALS can be used to investigate solid structures at the nanometer scale and enable the use of positronium properties as an additional diagnostic parameter. Here we present results from calibration of the PALS system with certificated reference materials (CRM).
Materials: Source of 22Na covered with layer of Kapton film, and after that parafilm from both sides was used in all experiments. Certified materials of No_5602-a (polycarbonate) and No_5601-a (fused silica) were used to ascertain if parameters were correctly identified.
Results: In an experiment three lifetime components were correctly identified. All of those components will always be present in the data in further experiments on biological samples. Lifetime components consist of: 196 ps for annihilations in AI an aluminium cover of the chamber, 386 ps for annihilations in thesource and in the Kapton foil, 463 ps for reactions with parafilm.
Conclusions: These parameters will be further used to correctly identify positron lifetimes in biological samples. Recently, a new method for imaging of positronium properties was invented and the first in-vivo images of positronium lifetime in humans were demonstrated with the multi-photon J-PET scanner. In order to correlate the positronium properties in tissue with the medically useful parameters, and to translate positronium imaging to clinics, comprehensive research of positronium properties in biological samples is needed.
Positronium image of the human brain in vivo
P. Moskal, J. Baran, S. Bass, J. Choiński, N. Chug, C. Curceanu, E. Czerwiński, M. Dadgar, M. Das, K. Dulski, K.V. Eliyan, K. Fronczewska, A. Gajos, K. Kacprzak, M. Kajetanowicz, T. Kaplanoglu, Ł. Kapłon, K. Klimaszewski, M. Kobylecka, G. Korcyl, T. Kozik, W. Krzemień, K. Kubat, D. Kumar, J. Kunikowska, J. Mączewska, W. Migdał, G. Moskal, W. Mryka, S. Niedźwiecki, S. Parzych, E. Perez del Rio, L. Raczyński, S. Sharma, Shivani, R.Y. Shopa, M. Silarski, M. Skurzok, F. Tayefi, K. Tayefi, P. Tanty, W. Wiślicki, L. Królicki, E. Ł. Stępień
abstract
Positronium is abundantly produced within the molecular voids of a patient?s body during positron emission tomography (PET). Its properties dynamically respond to the submolecular architecture of the tissue and the partial pressure of oxygen. Current PET systems record only two annihilation photons and cannot provide information about the positronium lifetime. This study presents the in vivo images of positronium lifetime in a human, for a patient with a glioblastoma brain tumor, by using the dedicated Jagiellonian PET system enabling simultaneous detection of annihilation photons and prompt gamma emitted by a radionuclide. The prompt gamma provides information on the time of positronium formation. The photons from positronium annihilation are used to reconstruct the place and time of its decay. In the presented case study, the determined positron and positronium lifetimes in glioblastoma cells are shorter than those in salivary glands and those in healthy brain tissues, indicating that positronium imaging could be used to diagnose disease in vivo.
