Tuesday, May 21, 2013

1305.4261 (C. Lang et al.)

Sub-millimeter nuclear medical imaging with reduced dose application in
positron emission tomography using beta-gamma coincidences

C. Lang, D. Habs, K. Parodi, P. G. Thirolf
Positron emission tomography (PET) permits a functional understanding of the underlying causes of many diseases. Modern whole-body PET systems reach a spatial resolution of 2-6 mm (FWHM). A limitation of this technique occurs from the thermalization and diffusion of the positron before its annihilation, typically within the mm range. We present a nuclear medical imaging technique, able to reach sub-millimeter spatial resolution in 3 dimensions with a reduced effective dose application compared to conventional PET. This 'gamma-PET' technique draws on specific medical isotopes, simultaneously emitting an additional photon accompanying the beta^+ decay. Exploiting the triple coincidence between the positron annihilation and the third photon, it is possible to separate the reconstructed 'true' events from background. In order to characterize the potential of this technique, MC simulations and image reconstructions have been performed. The achievable spatial resolution has been found to reach ca. 0.4 mm (FWHM) in each direction for the visualization of a 22Na point source. Starting with a source activity of only 1.48 MBq for 89Zr, corresponding to ca. 130 - 270 times less compared to a conventional PET examination using 18F-FDG, about 40 intersections (sufficient for a reliable image reconstruction of a point source) can be identified after a typical examination time of 900 seconds. This results in a strongly reduced effective dose of, e.g., 0.785 mSv for 89Zr-cmAb-U36, compared to the applied effective dose in a typical human PET examination with 18F-FDG of about 7.5 mSv. Increasing the applied effective dose to 7.5 mSv, the examination time will be reduced to 94 s for only 14.2 MBq of 89Zr-cmAb-U36. The reduced effective dose, or, the reduced examination time, surpass the performance of a conventional PET device by more than one order of magnitude.
View original: http://arxiv.org/abs/1305.4261

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