How do you use a 4D CT to account for hepatocellular carcinoma tumor motion?  

When planning SBRT cases for primary liver cancers, it is very difficult to see the tumor on the non-contrast 4D scan. How do you use information from the 4D CT to account for movement in your PTV expansion? 



Answer from: Radiation Oncologist at Academic Institution

Answer from: Radiation Oncologist at Community Practice