Interaction of positronium with dissolved oxygen in liquids

Abstract

The interaction of positronium with molecular oxygen dissolved in liquids is experimentally investigated. A computer software has been developed for fitting the positron annihilation lifetime spectra using parameters with clear physical meaning.

Prospects and Clinical Perspectives of Total-Body PET Imaging Using Plastic Scintillators

“…The value of sensitivity is given in arbitrary units, however the values in the left and right figures are shown in the same scale. 44 Sc or 82 Rb. The single-layer J-PET prototype with AFOV 5 50 cm weighs only approximately 60 kg.…”

“…37 This may include selection of double, triple and in general multicoincidence events. In particular it enables registration and identification of 2 (e 1 e À / 2g) and 3 photon (e 1 e À / 3g) annihilations, as well as prompt gamma emitted in case of some isotopes referred to as b 1 g emitters, such as for example, 10 C, 14 O, 22 Na, 34 Cl, 44 Sc, 48 V, 52 Mn, 55 Co, 60 Cu, 66 Ga, 69 Ge, 72 As, 76 Br, 82 Rb, 86 Y, 94 Tc, 110 In, 124 I. 44 Some examples of multiphoton events are shown pictorially in the right panel of Fig.…”

“…44 Sc-DOTA-ZHER2:342, 72-CAIX, 55,56 Integrin 59 PSMA, 69 SST2R 64 iv. Can be used in dual analysis with 2 radiotracers "pairs": 124 I-trastuzumab/ 18 F-FDG 70 This unique feature of the aforementioned radionuclides over the standard 2g radionuclides, which emit additional prompt g (eg, 44 Sc, 66 Ga, 82 Rb, 124 I) provides another rationale for the application of the TB-PET concept.…”

“…These radiotracers can be used in the TB-PET simultaneously and complementarily with for example, FDG to shorten the time between dosing of a radiopharmaceutical and a PET scan, which would reduce a diagnostic window, optimize the uptake and clearance of each radiotracer and minimize the risk of radiopharmaceuticals decay. The golden example of a dual tracer analysis application that became possible with TB-PET, is the FDA-approved 82 Rb-Chloride, which when applied concurrently with [ 18 F] fludeoxyglucose (FDG) would enable simultaneous assessment of metabolic rate and perfusion, mainly in the cardiovascular system. 54,76 This would allow to assess coronary arteries' occlusion and myocardium necrotic zone, as a perfusion (oxygen supply) and viability (oxygen consumption) synchronized tests.…”

“…In the body, the mean lifetime of ortho-positronium varies from approximately 1.8 ns in pure water to approximately 4 ns in human skin. 80 Moreover, both formation probability and mean lifetime depend on the concentration of the bio-fluids and bio-active molecules 81,82 and the mean lifetime can be established in the human body with the precision of approximately 20 ps. 29 There are investigations demonstrating differences between normal and cancerous cells with changes of the positronium lifetime during dynamic processes undergoing in model and living biological systems.…”