Researchers
have recently started applying direct beta-particle imaging to
in vivo small animal and radiopharmaceutical studies [3] and
[4]. One particular caveat in using PET instrumentation in
plant imaging is extremely small thickness of the leaf as an
annihilation medium for emitted positrons. For positron
energies around 1MeV (as in case of C-11), about 1 mm of
water equivalent material is required for positron conversion,
so most of the positrons would not annihilate inside the leaf,
therefore limiting both sensitivity and spatial resolution of the
imaging system. In this work we made an attempt of
determining whether direct imaging of positrons could be
beneficial in plant biology studies. We compared performance
of direct positron detector with a planar PET system and
explored benefits and limitations of use of direct beta imaging.