Feasibility of a Novel Design of a High Resolution/Sensitivity Animal Pet Scanner Using Thick and Thin Arrangement of Monolithic Scintillators Publisher



Sanaat A¹ ; Ay MR² ; Zaidi H¹
Source: 2019 IEEE Nuclear Science Symposium and Medical Imaging Conference# NSS/MIC 2019 Published:2019

Abstract

With the ever increasing use of transgenic and knockout laboratory animals to model human diseases, the need for high resolution and sensitivity small-animal PET scanners is becoming apparent. The well-established trade-off between spatial resolution and sensitivity is evident during the selection of crystal size. Higher thickness crystals provide a higher sensitivity but degrade the spatial resolution. In this work, we modeled two configurations of a small-animal PET scanner with 10 and 12 monolithic crystals using Monte Carlo simulations. In each configuration, half of the detector blocks have thick crystals (10 mm) whereas the second half has thin crystals (2 mm). This design is based on the Xtrim-PET preclinical scanner where in the first configuration, the block detectors with thick crystals face those with thin crystals and vice versa. In the second configuration, the block detectors with crystals of the same thickness (thick and thin) are arranged face-to-face in the full-ring polygonal geometry of the gantry. In addition, two modes of data acquisition were simulated: stationary and rotating. The gantry has no motion in the stationary mode, whereas the gantry recurrently rotates back and forth over the scan time with the angular step corresponding to half the size of the crystals in the rotating mode. The resolution and sensitivity evaluated using the NEMA NU4-2008 standards. The proposed design enables to achieve sub-millimetric spatial resolution (0.7 mm and 0.6 mm) and high sensitivity (4.3% and 3.1%) at the centre of the FOV for the first and second configurations, respectively. It can be concluded that the proposed design configuration enables to overcome the conventional tradeoff between sensitivity and spatial resolution, while achieving sub-millimetric spatial resolution and high sensitivity. © 2019 IEEE.