High-resolution 4 D pre-clinical SPECT / CT imaging of technetium transport within a heterogeneous porous media

11 A dynamic 99m Tc tracer experiment was performed to investigate the capabilities of combined 12 pre-clinical single photon emission computed tomography (SPECT) and x-ray computed 13 tomography (CT) for investigating transport in a heterogeneous porous medium. The experiment 14 was conducted by continuously injecting a 99m Tc solution into a column packed with 8 layers 15 (i.e., soil, silica gel, and 0.2-4 mm glass beads). Within the imaging results it was possible to 16 correlate observed features with objects as small as 2 mm for the SPECT and 0.2 mm for the CT. 17 Page 1 of 27 ACS Paragon Plus Environment Environmental Science & Technology