Research Article

Nonrigid Registration of Lung CT Images Based on Tissue Features

Algorithm 1

Structural invariance removing method.
Require: Suppose , are preselected point set. Every point in has a
     corresponding matched point in . The number of , is .
Ensure: Final set of matched feature pairs.
(1)  Let Q be a set of point pairs; , be sets of points.
(2)   ;
(3)  for   to
(4) do   number of points in which have nearest distance to Point
(5)     number of points in which have nearest distance to the point
       which corresponding to Point
(6)   the number of matched pairs between and
(7)  if     then
(8)     Point and its corresponding point
(9)  end if
(10) end for
(11) Return