Multicomponent positronium lifetime modes to nanoporous study of MgO-Al2O3 ceramics

Abstract Positronium (Ps) lifetime imaging is gaining attention to bring out additional biomedical information from positron emission tomography (PET). The lifetime of Ps in vivo can change depending on the physical and chemical environments related to some diseases. Due to the limited sensitivity, Ps lifetime imaging may require merging some voxels for statistical accuracy. This paper presents a method for separating the lifetime components in the voxel to avoid information loss due to averaging. The mathematics for this separation is the inverse Laplace transform (ILT), and the authors examined an iterative numerical ILT algorithm using Tikhonov regularization, namely CONTIN, to discriminate a small lifetime difference due to oxygen saturation. The separability makes it possible to merge voxels without missing critical information on whether they contain abnormally long or short lifetime components. The authors conclude that ILT can compensate for the weaknesses of Ps lifetime imaging and extract the maximum amount of information.

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Temperature dependence of positronium lifetime in cylindrical pores

physica status solidi (c) ◽

10.1002/pssc.200675803 ◽

2007 ◽

Vol 4 (10) ◽

pp. 3814-3818 ◽

Cited By ~ 3

Author(s):

R. Zaleski ◽

J. Goworek ◽

A. Kierys

Keyword(s):

Temperature Dependence ◽

Positronium Lifetime ◽

Cylindrical Pores

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Positronium lifetime in an ellipsoidal free-volume hole of polymers

Journal of Non-Crystalline Solids ◽

10.1016/0022-3093(94)90582-7 ◽

1994 ◽

Vol 172-174 ◽

pp. 806-814 ◽

Cited By ~ 32

Author(s):

Y.C. Jean ◽

H. Shi

Keyword(s):

Free Volume ◽

Positronium Lifetime ◽

Free Volume Hole

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Capillary condensation in porous alumina observed by positronium lifetime spectroscopy

Applied Surface Science ◽

10.1016/j.apsusc.2008.05.285 ◽

2008 ◽

Vol 255 (1) ◽

pp. 194-196 ◽

Cited By ~ 1

Author(s):

Eugeniu Ivanov ◽

Ion Vata ◽

Stefan Toderian ◽

Dorin Dudu ◽

Ion Rusen ◽

...

Keyword(s):

Capillary Condensation ◽

Porous Alumina ◽

Positronium Lifetime

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Positronium lifetime calculation

Physical Review D ◽

10.1103/physrevd.47.5183 ◽

1993 ◽

Vol 47 (11) ◽

pp. 5183-5186 ◽

Cited By ~ 4

Author(s):

A. A. Pivovarov

Keyword(s):

Positronium Lifetime

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Effects of Local Heating and Premelting in the Terminal Part of the e+ Track

Materials Science Forum ◽

10.4028/www.scientific.net/msf.733.15 ◽

2012 ◽

Vol 733 ◽

pp. 15-18 ◽

Cited By ~ 5

Author(s):

Dmitry Zvezhinskiy ◽

Sergey V. Stepanov ◽

Vsevolod Byakov ◽

Bożena Zgardzińska

Keyword(s):

Melting Point ◽

Temperature Dependence ◽

Local Heating ◽

Bulk Temperature ◽

Melting Points ◽

Terminal Part ◽

Slowing Down ◽

Positronium Lifetime ◽

Molten Region

The terminal part of the e+ track (the positron blob) is formed during ionization slowing down and subsequent ion-electron recombinations produced by a positron. It releases up to 1 keV of energy, which is converted into heat within few picoseconds. If a bulk temperature of a medium is below, but close enough to its melting point, some region of a substance may melt, yielding a peculiar temperature dependence of the lifetime (LT) spectra. We have estimated properties of the molten region with a help of macroscopic heat con- duction equation and suggested a model describing temperature dependence of the ortho- positronium lifetime in frozen methanol, ethanol, butanol and water close to their melting points.

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