A two-step approach for image segmentation during the treatment planning process is disclosed. In a first step, an automatic segmentation method can be used to generate a first, provisional segmentation. The first, provisional segmentation may be generated using fast, but less accurate segmentation methods. The first provisional segmentation may be used to generate a default treatment plan for approval. Once the default treatment plan is approved, a more robust, second image segmentation may be performed. The second segmentation may be used to design patient-specific devices that can be used to deliver the patient-specific medical treatment.
