A 2D-spline patient specific model for use in radiation therapy

Modeling of respiratory motion is very important for the efficacy of radiation therapy (RT) which is used in the treatment of cancer in the thorax and the abdomen. Having such a model is a key point to deliver, under breathing induced motion, less dose to the normal healthy tissues and higher dose to the tumor. Many methods have been developed to reduce the respiratory motion induced errors. While 4D CT based methods produce a number of separate frames at different positions in the respiratory cycle, a continuous motion model will be more efficient for radiation therapy. In this paper, we describe an approach based on the creation of a continuous patient specific model that takes into account respiratory signal irregularities and reproduces respiration-induced organ motion. This model has been validated on three patients. Our results show that including both phase and amplitude for the model reconstruction leads to higher accuracy compared to the use of only one of these two parameters.