A comparison of image quality and radiation dose between a cellular grid and a linear grid using a mammography phantom

Abstract

The aim of this study is to establish whether a cellular grid can offer any improvement over a linear grid in terms image quality and radiation dose for a single analogue mammography system.Using a prospective experimental design, a range of exposure factors and Perspex thicknesses were used to simulate conditions found in clinical practice. A Contrast Detail Mammography (CDMAM) test phantom was utilized to produce Image Quality Factor (IQF) and Mean Glandular Dose (MGD) data sets.An identical range of exposure factors/phantom thicknesses were selected for both grids and a direct comparison was made of the calculated IQF and the MGD for each pair of factors.The cellular grid produced a higher IQF for every exposure technique tested, when compared to the linear grid (increase: 1.2% to 35.8%, mean 15.8%, p < 0.005). MGD values with the cellular grid were also minimally increased for the majority of exposure techniques, (increase: −2.4% to 7.9%, mean 3.3%, p < 0.01).In this phantom study, use of the cellular grid resulted in increased IQF with an acceptable increase in MGD under all exposure conditions tested with the largest improvement in IQF seen in the extremes of phantom thickness. This suggests that use of a cellular grid in clinical practice might help improve cancer detection rates, without breaching current radiation dose guidelines for accepted dose levels and be particularly beneficial when examining both very small and very large breasts.