Setup and characterisation according to NEMA NU 4 of the pheno PET scanner, a PET system dedicated for plant sciences.

The pheno PET system is a plant dedicated Positron Emission Tomography (PET) scanner consisting of fully digital photo multipliers with lutetium-yttrium oxyorthosilicate crystals and located inside a custom climate chamber. Here, we present the setup of pheno PET, its data processing and image reconstruction together with the performance according to the NEMA standard for small animal PET systems. The spatial resolution for a 22 Na point source at a radial distance of 5mm to the center of the Field-of-View (FOV) is 1.45mm, 0.82mm and 1.88mm with Filtered Back Projection in radial, tangential and axial direction, respectively. A hot rod phantom with 18 F gives a spatial resolution of up to 1.6mm. The peak noise-equivalent count rates are 550kcps@35.08MBq, 308kcps@33MBq and 45kcps@40.60MBq for the mouse, rat and monkey size scatter phantoms, respectively. The scatter fractions for these phantoms are 12.63%, 22.64% and 55.90%. We observe a peak sensitivity of up to 3.6% and a total sensitivity of up to S A,tot =2.17%. For the NEMA image quality phantom we observe a uniformity of %STD=4.22% with Ordinary Poisson Maximum Likelihood Expectation-Maximization with 52 iterations. Here, recovery coefficients of 0.12, 0.64, 0.89, 0.93 and 0.91 for 1mm, 2mm, 3mm, 4mm and 5mm rods are obtained and spill-over ratios of 0.08 and 0.14 for the water-filled and air-filled inserts, respectively. The pheno PET and its laboratory are now in routine operation for the administration of [ 11 C]CO 2 and non-invasive measurement of transport and allocation of 11 C-labelled photoassimilates in plants.