Positioning reproducibility with and without rotational corrections for 2 head and neck immobilization systems, Courneyea et al. 2015. Someone could do that kind of study and only change the immobilization comparison to AlignRT open mask vs. closed mask without AlignRT comparison. I am interested in the realized accuracy of the structures on the edges of PTV before and after treatment, not rotations or couch shifts that has been done. Hope that someone does this in the future.