Digital Tomosynthesis

Abstract

The purpose of this chapter is to present a brief description of digital tomosynthesis, a three-dimensional (3D) imaging technique that overcomes the problems of conventional two-dimensional (2D) tomography. The technique involves image acquisition, image reconstruction, and image display and communication. While image acquisition is such that the X-ray tube rotates through a limited angle about the detector which is often stationary, to obtain a number of projection data are taken from different angles. These data are subsequently reconstructed to produce individual slices of the volume of tissue scanned, using algorithms specially developed for tomosynthesis. There are two types of designs for image acquisition in digital tomosynthesis: step-and-shoot system and continuous scan system. While, in the former method, the X-ray tube that moves to every angular position stops, an exposure is taken and the tube then moves to the next angular position; in the latter system, the X-ray tube moves during the scanning of the object. Digital tomosynthesis (DT) is being applied to general radiographic imaging and to digital breast imaging referred to as digital breast tomosynthesis (DBT).

Major imaging system components include the X-ray tube and housing designed to rotate during the data acquisition, collimation and filtration, breast support, breast compression device, and either a full-field indirect flat-panel digital detector {amorphous silicon (a-Si) cesium iodide (CsI)} or a full-field direct flat-panel digital detector (a-Selenium). Furthermore DT is characterized by several parameters such as the sweep angle, sweep direction, patient barrier-object distance, number of projections, and total radiation dose. Additionally an overview of image reconstruction methods of DT, image display and communication, and radiation dose considerations is presented. Finally, this chapter concludes with an outline of synthesized 2D digital mammography (DM) and clinical applications of DT.