abstract
- Positron Emission Tomography (PET) is a non-invasive technique to visualize metabolic and physiological processes in vivo. Excellent imaging capabilities such as spatial resolution and count rate performance are essential to achieve accurate information about the observed processes. It is for this purpose that the LabPET scanner, an avalanche photodiode (APD)-based fully digital scanner PET scanner, was initially developed. Two variants of the scanner exist: LabPET4 and LabPET8 with 3.75 and 7.5 cm axial lengths respectively. The range of the transaxial FOV is up to 10 cm therefore it can easily accommodate mice and rats. The aim of this work is to evaluate LabPET4 imaging in several phantoms and small animals. Spatial resolution was determined using a point source and hot spots phantoms. The latter were used to assess recovery coefficients (RC) obtained by taking the ratio of hot spot maximum values compared to the biggest spot maximum value. FBP reconstructed tangential/radial resolution is 1.3/1.4 mm FWHM (2.5/2.4 FWTM) at the field of view center. With an Ultra Micro Hot Spot Phantom, 1 mm spots are clearly resolved. Count rate performance was obtained for mouse-size and rat-size phantoms. For mouse phantom, scatter fraction is 18%, noise equivalent count rate (NEC) peak is 120 kcps at 5.6 mCi and true coincidences peak is 215 kcps at 6.6 mCi. Mice and rats were imaged with Na18F and 18FDG. LabPET4 imaging capabilities achieve state-of-the-art requirements for molecular imaging and therefore can provide excellent quality images.© 2008 American Association of Physicists in Medicine.