The CIRS Model 010 & 011A Breast Phantoms contain targets that are engineered to test the threshold of the new generation of mammography machines. Model 010 phantoms are available in 4, 5 and 6 cm thickness, with specified glandular tissue compositions. Model 011A is 4.5 cm thick and simulates an average glandular tissue composition. Both phantoms include a removable 0.5 cm adipose tissue equivalent layer. The Model 010 & 011A were designed to test the performance of any mammographic system. Objects within the phantoms simulate calcifications, fibrous calcifications in ducts and tumor masses. Test objects within the phantoms range in size from those that should be visible on any system to objects that will be difficult to resolve on the best mammographic systems. CIRS resin material mimics the photon attenuation coefficients of a range of breast tissues. Average elemental composition of the human breast being mimicked is based on the individual elemental composition of adipose and glandular tissue reported by Hammerstein. Attenuation coefficients are calculated by using the ¡°mixture rule¡± and the Photon Mass Attenuation and Energy Absorption Coefficient Table of J.H. Hubbell.The methodology and design of these phantoms was developed by Dr. Panos Fatouros and his associates at the Medical College of Virginia.