Patterns of intrafractional motion and uncertainties of treatment setup reference systems in accelerated partial breast irradiation for right- and left-sided breast cancer

It appears that the fiducial markers placed in the seroma cavity exhibit side dependent directional intrafractional motion, although additional data may be needed to further validate the conclusion. The bony anatomy-based treatment setup improves the accuracy over laser-tattoo. But it is inadequate to rely on bony anatomy to assess intrafractional target motion in both magnitude and direction.