TY - JOUR T1 - Impact of high radioactivity concentrations on PET image quality and quantification accuracy JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1852 LP - 1852 VL - 56 IS - supplement 3 AU - Thomas Andersen AU - Poul-Erik Braad AU - Poul Høilund-Carlsen Y1 - 2015/05/01 UR - http://jnm.snmjournals.org/content/56/supplement_3/1852.abstract N2 - 1852 Objectives PET myocardial perfusion imaging is often performed with high activities of 15O or 82Rb due to their short half-life. Depending on detector technology and implemented dead-time corrections associated dead-time losses can cause artifacts and quantification inaccuracies. In the current work, we present the results of high activity phantom measurements performed on a series of GE PET/CT scanners.Methods Quantitation accuracy and uniformity was determined in a decaying 18 cm high, 20 cm diameter cylindrical phantom initially filled with 1500 MBq 18F. The background and six spherical inserts with volumes ranging from 0.52 to 26.52 ml inside the NEMA/IEC torso phantom were filled with a homogeneous aqueous solution of initially1500 MBq 18F (sphere-to-background ratio of approximately 8). The activity recovery in each lesion was determined on reconstructed images. Measurements were performed on the decaying phantoms using the GE Discovery VCT (DVCT) (BGO-based), GE Discovery RX (DRX) and GE Discovery 690 (D690) (both LYSO-based) systems.Results Quantitation errors calculated from the listmode binning and subsequent averaging of activity concentrations were below 10% at activities of 290 MBq, 621 MBq and 799 MBq on the DVCT, DRX and D690 systems, respectively. At a clinical relevant activity of 400 MBq, the quantification errors were 12.7%, 7.6% and 2.9% for the DVCT, DRX and D690, respectively.Conclusions The quantifications were unaffected except at very high count rates. LYSO crystal-based scanners performed significantly better at high activities in the FOV compared to the BGO-based system in terms of total activity in the phantom, consistent with physical crystal properties. Improved dead-time modeling and faster electronics furthermore improved the image quality and quantification accuracy on the D690 while the DVCT had a 12.7% quantification error suggesting it to be less suitable for myocardial perfusion studies.Research Support None ER -