1. A system for modeling side effects for lung cancer patients, the system comprising: an input configured to receive lung cancer patient information representing at least lung bullae information of the lung cancer patient; a processor configured to apply a model to the lung cancer patient information, to generate at least a side-effects prediction for the lung cancer patient as a response to radiation therapy, wherein the processor is configured to determine a ratio of the lung bullae to a lung volume, and wherein the model is applied with only said ratio to the side-effects prediction, the side-effects prediction comprising pneumonitis; and a display configured to output the side-effects prediction generated from the model for the lung cancer patient.