A Large Volume PET Scanner for Low Dose Applications

A large field-of-view (FOV) LSO PET scanner (Siemens Molecular Imaging) has been investigated for low dose applications. Five panels of dimension 52 cm (axial) times 37 cm (transaxial) comprise 350 detector blocks, each incorporating a 12 times 12 matrix of 4 times 4 times 20 mm³ elements. Emission and transmission data are acquired simultaneously while the panels rotate at 30 rpm. This design, with a spatial resolution of 4.5 mm and a sensitivity of 2.3%, is particularly appropriate for applications where a large FOV (52 cm axial, 70 cm transaxial) and low levels of injected radioactivity are essential. The scanner is ideally suited for translational research using animals as models for human disease. The extended patient port facilitates the imaging of larger animals such as dogs that cannot be imaged with a microPET scanner. The large axial FOV and dynamic data acquisition allows multi-organ kinetics to be followed. Animals with natural occurring tumors can be imaged and response to radiation or chemo-therapy followed. The device is also suitable for assessing the functional status of premature infants, beyond just the basic monitoring of respiration and heart beat. A premature infant can be imaged dynamically without removal from the cradle or incubator in a single bed position after injection of very low levels of ¹⁸F-FDG. This paper will present imaging studies performed with low injected doses, including multi-organ kinetics of both pre-clinical and clinical subjects.