The present disclosure provides systems, methods, and computer-readable storage media for detecting an anatomical region of interest for radiotherapy planning. Embodiments of the present disclosure may identify a plurality of objects in a medical image and select a subset of the objects by applying a morphology filter to the plurality of objects. The morphology filter may determine a morphological feature associated with each of the plurality of objects and exclude at least one object from the subset when the morphological feature of the at least one object exceeds a predetermined threshold. Embodiments of the present disclosure may also classify the objects in the subset into one of a predetermined set of shapes and detect the anatomical region of interest based on the classified objects in the subset.