Breast CT

In the 1990s, various flat panel detectors were developed and used to construct digital x-ray systems for general radiography as well as mammography applications. The availability of these detectors facilitated research and development of cone beam computed tomography (CBCT) techniques in academic institutions. With these techniques, a cone shaped beam, like those used in radiography, fluoroscopy or mammography, is used to rotate around and scan the patient. One of these efforts was aimed to implement dedicated breast CT using the pendant geometry, with which the patient lies prone on the table with one of her breasts protruding downward through an opening and scanned by a CBCT system underneath the table. The use of CBCT techniques for dedicated BCT was first proposed independently by Boone et al. (2001) at the University of California at Davis and Ning et al. (2002) at the University of Rochester (O’Connell et al. 2010, Lindfors et al. 2008, Ning et al. 2007, Boone et al. 2006, Chen and Ning 2002, Boone et al. 2001). The former constructed the first patient imager for clinical evaluation. The latter led to the first effort to commercialize the BCT technology. Patient studies conducted to date have shown that BCT images are superior to mammography in detecting and visualizing breast anatomy and soft tissue masses but are more limited in imaging small microcalcifications. A third group at the Duke University has recently constructed a patient imager with a specially designed quasimonoenergetic x-ray source to improve the image quality (McKinley et al. 2005, Tornai et al. 2005). Two other groups, one at the University of Massachusetts and the other at The University of Texas MD Anderson Cancer Center, have constructed bench top experimental systems to image mastectomy breast specimens in an effort to investigate the imaging properties of BCT (O’Conner et al. 2008, Lai et al. 2007, O’Conner et at. 2007, Yang et al. 2007). The latter has also proposed and investigated the use of a collimated x-ray beam to scan a preselected volume-of-interest to allow smaller microcalcifications or other details to be seen without increasing the integral breast dose (Chen et al. 2009, Lai et al. 2009, Chen et al. 2008). To enhance the visibility of cancer tissue, BCT with contrast injection has been explored and investigated (Prionas et al. 2010). Research groups in USA as well as Europe have also begun to develop and investigate improved BCT techniques in an effort to bring BCT into practical use (Russo et al. 2010, Russo et al. 2010, Kyriakou et al. 2008, Ning et al. 2006, von Smekal et al. 2004).