I have a problem statement- to develop an application for processing DICOM images for diagnostic applications from scratch. It includes:

Image processing- model based segmentation and registration (C++)
Visualization- 2D and 3D image visualization (C++)
Graphical User Interface (Python)

Is it feasible to develop this using C++ (for large chunk of image data) and Python for the GUI?
What are the pros and cons of using openCV? 
Which libraries would be suitable for this?
I would say go with VTK, ITK and Qt. Python brings nothing to the table in terms of GUI compared against Qt. VTK/ITK can read DICOM for you and probably also do segmentation and registration as needed.
DICOM image processing, visualization and GUI- C++ and Python