JRSBRT 4.2, p. 153-161

Physics Investigation
Efficient and accurate stereotactic radiotherapy using flattening filter free beams and HexaPOD robotic tables
Morten Nielsen, Christian R. Hansen, Carsten Brink, Anders S. Bertelsen, Charlotte Kristiansen, Stefan S. Jeppesen and Olfred Hansen

Flattening filter free (FFF) high dose rate beam technique was introduced for brain stereotactic radiosurgery (SRS) and lung Stereotactic Body Radiotherapy (SBRT). Furthermore, a HexaPOD treatment table was introduced for the brain SRS to enable correction of rotational setup errors.

19 filter flattened (FF) and 57 FFF brain SRS treatments, as well as 451 FF and 294 FFF lung SBRT treatments were evaluated to assess differences in intrafractional motion (IFM) between FF and FFF treatments. For brain SRS the accuracy of rotational corrections was assessed as well.

For SRS the treatment time was reduced by 21%, and for SBRT the treatment time was reduced by 25%. However, only for SBRT the IFM was significantly reduced, from 1.9 mm to 1.6 mm. For brain SRS, table correction in 6D greatly improves patient setup precision observed as a reduction in mean residual rotational setup error from 0.3° (SD1.2°) to 0.06° (SD 0.3°).

Keywords: SRS, SBRT, stereotactic, brain, lung, FFF, intrafractional motion, rotations, HexaPOD.