Figure 4: The effect of air cavities on the dose distributions and plan parameters between MC (thin lines) and PB (thick lines). (a) 95, 70, 30% isodose lines and an EUD difference of 13% for case number 1, and (b) 95, 50, 20% isodose lines and an EUD difference of 14% for case number 7. The air cavities are part of the PTV.