A prior MDACC study, before the recent phase III multicenter by Steven Frank, showed that protons overall cost less than IMRT if the episode of care includes 90 days of followup.
The initial difference between the modality's upfront cost crosses over around week 7 of H&N chemoRT due to IMRT having more Gtubes, resims, replans, IV hydration and unplanned admissions. This cost was measured in terms of direct medical expenses billed to insurance, not counting any indirect patient costs like time lost from work or decrease in quality adjusted life-years.