A homemade phantom for image quality evaluation in contrast enhanced spectral mammography (CESM)

Abstract

The aim of the study is to assess the feasibility of a homemade phantom for image quality evaluation in Contrast Enhanced Spectral Mammography (CESM). The phantom was composed by a PMMA slab with holes of different diameters (10, 5 and 2.5 mm) and thicknesses (5, 4, 3 and 2 mm) filled with diluted iodine contrast medium, resulting in concentrations of 1.9, 1.5, 1.1 and 0.7 mg/cm2 (±0.2 mg/cm2 ), similar to the clinical concentrations. Furthermore, we added tissue-equivalent slabs with anatomical background and we simulated 3 different configurations equivalent to 32, 60 and 90 mm breast thicknesses. Image acquisitions were performed on a Hologic 3Dimensions mammography system using AEC clinical parameters. The acquisitions included a low energy exposure followed by an high energy one, and the resulting processed images were a subtraction of the 2 acquired images. For each configuration, the CNR on the low, high and subtracted images were calculated. The results showed that CNR values measured on the processed subtracted images were much higher respect to the CNR measured on the “for processing” low and high energy images. Furthermore, as expected, an increase in CNR for increasing iodine concentration was verified on the processed images, but not always on raw images that contained anatomical background. Preliminary results showed that the phantom is suitable for image quality evaluation in CESM but further studies with different acquisition parameters and on different mammography systems are necessary to assess the repeatability and the consistency of the measurements.