A tissue equivalent phantom series for mammography dosimetry

Abstract

A breast tissue equivalent series (BRTES) of phantoms are manufactured to mimic both the attenuation and density of the range of glandular and adipose tissue compositions encountered in mammography. The BRTES simulates breast tissues across the range of 20 to 70 % glandularity and can be assembled in a variety of thicknesses to represent a compressed breast thickness corresponding to glandularity to simulate various patient demographics. The fabrication techniques are presented and physical properties of the completed series of phantoms are described. The BRTES phantoms provide a dosimetry comparison with commonly used phantoms, including the ACR accreditation phantom and BR12, a 50% glandularity tissue equivalent material. The comparison shows that the mean glandular dose is a strong function of compressed breast thickness and tissue composition. Patient doses measured using phototimed exposures with the BRTES phantoms can be a factor of two greater than, or less than, the doses predicted using conventional phantoms.