1. A non-transitory processor readable medium storing code representing instructions to be executed by a processor configured to perform image segmentation, the code comprising code to cause the processor to: receive 3-dimensional image data associated with a target and a background, the target including an anatomic structure, the background including tissue surrounding the anatomic structure; select a 2-dimensional seed image slice from the 3-dimension image data; define a first boundary of the target on the 2-dimensional seed image slice, the first boundary dividing the 2-dimensional seed image slice into a target portion associated with the target and a background portion associated with the background; select a 2-dimensional neighboring image slice from the 3-dimensional image data; generate a deformation field through deformable image registration conducted between the 2-dimensional seed image slice and the 2-dimensional neighboring image slice; and define a second boundary of the target on the 2-dimensional neighboring image slice by applying the deformation field to the first boundary of the target.