The impact of tumor geometrical changes on IMPT treatment plans

Radiation therapy treatment is often delivered in a fractionated manner over a period of time. A previous approach to treatment planning involves solving a single planning problem before the start of the treatment and delivering an equally divided daily dose to accomplish the total dose. However, this static delivery approach has a big flaw due to many aspects of uncertainty involving radiation therapy. One common such uncertainty for many lung cancer patients is the reduction in tumor volume during the course of the treatment. The specific goal of this study is to evaluate the potential for lung adaptive proton therapy to adjust the treatment plan in response to these changes in order to reduce normal tissue doses. Dose volume statistics are compared between non-adaptive and adaptive treatment plans.