Open-source toolkit for radiation therapy research, an extension of 3D Slicer. Features include DICOM-RT import/export, dose volume histogram, dose accumulation, external beam planning (TPS), structure comparison and morphology, isodose line/surface generation, etc.
DICOM FID (spatial fiducials) support could be added. There are function skeletons for this in the SRO plugin.
A test file: https://pocus.cs.queensu.ca/#item/5ccb307901d4930406c42885