How do you control for organ motion when treating pancreatic cancer?

Typically I use a forced breath hold to essentially eliminate motion so that setup variation is all that we have to deal with after delineating a tumor on CT.

Options for managing respiratory motion include gating, abdominal compression, “ABC” (active breathing control), “DIBH” (deep inspiration breath hold) and others. I’m not aware of literature comparing the relative strengths and weaknesses of these approaches, particularly in pancreatic cancer.

My practice is to use a 4D CT to identify tumor motion at the time of simulation, thereby defining an “ITV” (internal target volume), which accounts for motion. Although there are extreme cases with over 2 cm of motion in maximal dimension, I find that motion is more typically in the range of 7-8 mm for pancreatic tumors. I account for this motion by defining a PTV as an expansion of the ITV, but I do not make an effort to control for organ motion. Un...