Affiliations: Department of Imaging Sciences, University of
Rochester Medical Center, Rochester, NY, USA
Note: [] Corresponding author: Weixing Cai, Department of Imaging
Sciences, University of Rochester Medical Center, 601 Elmwood Avenue Box 648,
Rochester, NY, USA. Tel.: +1 585 275 1349; Fax: +1 585 276 0373; E-mail:
weixing_cai@urmc.rochester.edu
Abstract: In flat-panel detector-based cone beam CT breast imaging (CBCTBI)
systems, scattering is an important factor that degrades image quality. It is
not practical to measure the scattering profiles of a breast for all view
angles in a patient study, but it is possible to develop a method to estimate
the scattering profiles based on information acquired from breast phantom
studies. A new scattering correction method is proposed for clinical CBCTBI in
this study. The scattering profiles of three anthropomorphic uncompressed
breast phantoms of different sizes were thoroughly investigated, and the
results indicated that though phantom size differed, the scattering profiles
were mainly determined by local breast diameters, which are the approximate
diameters of coronal slices that are perpendicular to the nipple-to-chestwall
direction. Thus for scattering correction purposes it is possible to establish
a relationship between location breast diameters and local scattering profiles,
namely the fitted smooth curves of scatter-to-primary ratios (SPR) and
normalized scattered radiations (NSR). In clinical CBCTBI studies, after the
local breast diameters are sampled and measured on projection images, the
scattering image for every projection image can be generated based on the
established relationship, and the projection images can be corrected using
either the SPR based method or the NSR based method. Phantom studies and
clinical studies showed that both the SPR and NSR methods are able to correct
cupping artifacts and reduce reconstruction error. The SPR method does not
increase tissue contrast or noise while the NSR method increases both.
Keywords: Cone beam CT, scatter correction, breast imaging
