Method for task-based evaluation of clinical FFDM and DBT systems using an anthropomorphic breast phantom
Because breast phantoms are central for evaluating 2D and 3D breast imaging systems, it is important to develop anthropomorphic, realistic phantoms that can be used in task-based assessment. The current phantoms available for use with full field digital mammography (FFDM) and digital breast tomosynthesis (DBT) are uniform or have otherwise unrealistic background texture. However, this work presents a task-based methodology for evaluating FFDM and DBT systems using two components: An anthropomorphic breast phantom created through inkjet printing and realistic pathological inserts with two types of microcalcifications (MCs). To create the phantom, a virtual breast was first modeled, then digitally compressed to a 4 cm thickness. To realize the phantom, virtual model was printed with an inkjet printer in a slice-by-slice fashion using iohexol-doped ink. The MC inserts were created using two types of materials. One set of MCs were made using calcium hydroxyapatite (HA) powder, and the other was made from sodalime coated glass (SLG) microspheres. The composite phantom plus two types of inserts was imaged on two commercially available FFDM/DBT systems: The GE Senographe Essential and the Hologic Selenia Dimensions. For the acquisitions, the automatic exposure control was used to determine a typical mammographic beam based on the phantom thickness. In addition, a similar a similar average glandular dose was used for both systems. A four alternative forced choice (4AFC) study was conducted to demonstrate the utility of the methodology and to evaluate the systems. Results of the 4AFC study showed higher detection of calcs for DBT versus FFDM on the GE system, but the reverse on the Hologic system. In this work, a breast phantom as created from inexpensive and easily accessible materials. This methodology is promising for the objective evaluation of task performance for 2D and 3D breast imaging systems.
