Development and production of a prototype iodine contrast phantom for CEDEM.

ABSTRACT

Phantoms containing iodine details with clinically relevant iodine concentrations are required to systematically study dose requirements, for quality assurance and optimizing exposure parameters and protocols for contrast enhanced dual energy mammography (CEDEM) applications. Most such phantoms use liquid iodine solutions, challenging the user with air inclusions, evaporation or the necessity for changing the iodine concentration through refilling. A prototype phantom with an array of sintered solid iodine-containing platelets with iodine area weights of 0, 0.25, 0.5, 1, 1.5 and 2 mg cm(-2) is described. Disks containing various iodine concentrations were produced using polymer sintering of Iopamidol embedded into a polystyrene/graphite matrix. Iopamidol-containing platelets with a diameter of 0.5 cm and thickness of 550 µm forming an array with gradually increasing iodine area weight, were embedded in PMMA to allow statistical analysis of contrast and contrast-to-noise ratio (CNR). The homogeneity of the plates was tested and images of the phantom were acquired to assess the iodine area density progression and to evaluate phantom accuracy. The phantom was imaged on a mammography system applying low and high energy spectra as used for CEDEM. The disks show good homogeneity. Uncertainties in absolute iodine area weight were estimated ±5%. The iodine CNR showed a linear correlation with R(2) > 0.99. Polymer powder sintering works well for producing stable iodine contrast phantoms without the necessity to handle liquid iodine solutions. Thus, it is a promising approach to construct phantoms not only for CEDEM but also angiography or other contrast enhanced methods with iodine details for quality control or research purposes and optimization.