  While drastic improvements in CT technology have occurred in the past 25
years, spatial resolution is one area where progress has been limited until
recently. New photon counting CT systems, are capable of much better spatial
resolution than their (energy integrating) predecessors. These improvements
have the potential to improve the evaluation obstructive coronary artery
disease by enabling more accurate delineation between calcified plaque and
coronary vessel lumen. A new set of vessel phantoms has been designed and
manufactured for quantifying this improvement. Comparisons are made between an
existing clinical CT system, a prototype photon counting system, with images
from a micro CT system being used as the gold standard. Scans were made of the
same objects on all three systems. The resulting images were registered and the
luminal cross section areas were compared. Luminal cross-sections near
calcified plaques were reduced due to blooming, but this effect was much less
pronounced in images from the prototype photon counting system as compared to
the images from the clinical CT system.
