If you are doing a lot of work with DICOM, then you can build the vtk-dicom package and use the vtkDICOMReader. It has many more features than the vtkDICOMImageReader that is built into VTK.
For orientation, it has a method GetPatientMatrix() that returns a vtkMatrix4x4. This matrix can be applied to the actor (in your case, a vtkVolume?) with the method SetUserMatrix() to put it into DICOM Patient Coordinates. In this coordinate system, you can point the camera in the direction (0, 1, 0) to get a front view.