The treatment planning engine empowers radiation treatment decision makers, such as a clinician, to efficiently identify optimal radiation treatment results for a given patient. Specifically, the treatment planning engine generates a set of recommended treatment results based on patient images, patient contours, and prior patient data. A user interface simultaneously displays the patient images and contours with the recommended treatment results. The clinician is able to adjust the contours in the user interface and, in real-time, evaluate the impact on the tumor volume and the toxicity risk to the nearby anatomical structures. With the user interface, the clinician can visualize the relationship between radiation delivery to the contours and the resulting recommended treatment results, allowing the clinician to make informed decisions about certain trade-offs during radiation treatment planning for the patient. The treatment delivery engine generates a radiation treatment plan based on a recommended treatment result selected by the clinician.