Tilted.

Simultaneous integrated boost plans are appealing when treating the prostate and pelvic nodes. But when you are also targeting positive nodes with separate boost volumes, how accurately are you hitting all those different volumes? This study found that lymph node target displacement was significantly higher with prostate fiducial alignment than with pelvic bone alignment. When using prostate-based IGRT alignment, they estimated that at least 3-5mm (except 8-9mm superior/posterior) margins is necessary to simultaneously cover lymph node boost targets. | Wu, Adv Radiat Oncol 2022