Convert 3D Segmentation to contours along different axis

If I use SlicerRT to export a segmentation to a Dicom RTSS file using , the 2D contours are all along axial slices. Is there a way to export the contours along a perpendicular direction?

For that you will need to use a reference volume differently oriented. Looking at the exporter code the transform does not need to be hardened. Just make sure its Z axis points to the direction perpendicular to the contours you want. Please note that this volume will be exported to DICOM as well.