In this paper we propose a new framework to simultaneously
segment and register lung and tumor in serial CT
data. Our method assumes nonrigid transformation on lung
deformation and rigid structure on the tumor. We use the BSpline-
based nonrigid transformation to model the lung deformation
while imposing rigid transformation on the tumor
to preserve the volume and the shape of the tumor. In particular,
we set the control points within the tumor to form a
control mesh and thus assume the tumor region follows the
same rigid transformation as the control mesh. For segmentation,
we apply a 2D graph-cut algorithm on the 3D lung
and tumor datasets. By iteratively performing segmentation
and registration, our method achieves highly accurate
segmentation and registration on serial CT data. Finally,
since our method eliminates the possible volume variations
of the tumor during registration, we can further estimate
accurately the tumor growth, an important evidence in lung
cancer diagnosis. Initial experiments on five sets of patients¡¯
serial CT data show that our method is robust and
reliable.
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