Table 2. The alignment accuracy of four hidden target tests are presented for the first two beamline setups and two different CT datasets.

The distance of the ballbearing to the beam isocentre was captured via radiochromic film in the Y and Z axes. Measurement uncertainties (as described in Section 2.4.1) are shown for each axis; the two errors are combined in quadrature to give the total uncertainty in the 2D measurement.

	Distance to isocentre (mm)
Configuration	Y (±0.050)	Z (±0.050)	2D (±0.071)
Beamline setup 1, CT dataset 1	0.820	0.017	0.820
Beamline setup 1, CT dataset 2	0.393	0.008	0.394
Beamline setup 2, CT dataset 1	0.773	0.145	0.825
Beamline setup 2, CT dataset 2	1.022	0.161	1.071