Table 2.

Mean (±1SD) gamma pass rate difference between the original EPID dose image resolution of 0.255 mm (left columns) and 1mm resolution (right column) for lung SABR VMAT plans delivered with different collimator, MLCFS and MLCShift variations. Each plan consisted of two Arcs (Arc1 and Arc2). A lower gamma pass rate number indicates greater sensitivity to the introduced‐variation.

Variation type/magnitude		Gamma pass rate (%, mean ± SD) EPID original image resolution of (0.255 mm)				Gamma pass rate (%, mean ± SD) EPID image resolution of (1 mm)
		3%/3 mm	2%/2 mm	2%/1 mm	1%/1 mm	3%/3 mm	2%/2 mm	2%/1 mm	1%/1 mm
Collimator (degree)
+1°	Arc1	100.0 ± 0.0	100.0 ± 0.0	99.98 ± 0.0	99.66 ± 0.0	99.50 ± 0.0	97.37 ± 0.0	94.27 ± 0.0	88.51 ± 0.0
	Arc2	100.0 ± 0.0	100.0 ± 0.0	100.0 ± 0.0	99.67 ± 0.0	99.64 ± 0.0	97.67 ± 0.0	88.88 ± 0.0	83.80 ± 0.0
+5°	Arc1	100.0 ± 0.0	99.87 ± 0.1	93.27 ± 3.0	90.73 ± 2.4	99.64 ± 0.3	97.67 ± 2.0	88.88 ± 6.8	83.80 ± 8.6
	Arc2	100.0 ± 0.0	99.90 ± 0.1	92.65 ± 2.5	90.85 ± 2.3	99.48 ± 0.1	95.67 ± 1.9	85.83 ± 6.2	81.47 ± 7.7
−2°	Arc1	100.0 ± 0.0	100.0 ± 0.0	99.42 ± 0.0	98.88 ± 0.0	99.64 ± 0.0	96.32 ± 0.0	89.21 ± 0.0	83.87 ± 0.0
	Arc2	100.0 ± 0.0	100.0 ± 0.0	99.34 ± 0.0	98.65 ± 0.0	99.64 ± 0.0	96.47 ± 0.0	89.16 ± 0.0	83.61 ± 0.0
−5°	Arc1	100.0 ± 0.0	98.82 ± 1.3	89.85 ± 1.3	87.17 ± 2.3	99.31 ± 0.2	92.43 ± 1.1	79.64 ± 1.6	73.98 ± 3.5
	Arc2	100.0 ± 0.0	99.08 ± 1.3	89.75 ± 3.7	87.40 ± 4.6	99.28 ± 0.4	92.91 ± 1.6	79.63 ± 4.2	73.95 ± 6.3
MLCFS (mm)
+1	Arc1	100.0 ± 0.0	100.0 ± 0.0	96.77 ± 0.9	92.51 ± 1.8	99.47 ± 0.3	96.90 ± 0.8	77.32 ± 3.2	73.85 ± 4.3
	Arc2	100.0 ± 0.0	100.0 ± 0.0	98.13 ± 0.9	93.83 ± 1.7	99.68 ± 0.2	97.43 ± 0.9	77.62 ± 3.6	74.43 ± 4.4
+2	Arc1	100.0 ± 0.0	97.95 ± 0.0	79.02 ± 0.0	76.18 ± 0.0	99.32 ± 0.0	85.82 ± 0.0	74.12 ± 0.0	70.70 ± 0.0
	Arc2	99.96 ± 0.0	98.81 ± 0.0	78.41 ± 0.0	74.30 ± 0.0	99.99 ± 0.0	86.85 ± 0.0	73.74 ± 0.0	68.76 ± 0.0
+5	Arc1	81.36 ± 0.0	68.76 ± 0.0	64.05 ± 0.0	60.61 ± 0.0	78.08 ± 0.0	67.12 ± 0.0	63.70 ± 0.0	59.87 ± 0.0
	Arc2	79.12 ± 0.0	67.73 ± 0.0	64.52 ± 0.0	61.33 ± 0.0	75.77 ± 0.0	67.15 ± 0.0	63.84 ± 0.0	59.36 ± 0.0
−1	Arc1	100.0 ± 0.0	100.0 ± 0.1	96.39 ± 1.2	92.47 ± 1.9	99.33 ± 0.5	96.55 ± 1.2	77.71 ± 3.6	73.63 ± 3.6
	Arc2	100.0 ± 0.0	99.92 ± 0.2	96.14 ± 3.0	92.84 ± 2.9	99.62 ± 0.2	97.09 ± 1.0	77.92 ± 4.0	74.32 ± 4.1
−2	Arc1	100.0 ± 0.0	96.36 ± 0.0	79.75 ± 0.0	75.10 ± 0.0	99.53 ± 0.0	84.24 ± 0.0	75.71 ± 0.0	69.64 ± 0.0
	Arc2	100.0 ± 0.0	96.62 ± 0.0	78.67 ± 0.0	73.98 ± 0.0	95.56 ± 0.0	84.56 ± 0.0	72.50 ± 0.0	66.73 ± 0.0
MLC shift (mm)
+1	Arc1	100.0 ± 0.0	100.0 ± 0.0	95.07 ± 4.3	91.13 ± 5.4	99.46 ± 0.4	96.64 ± 1.1	77.97 ± 3.6	74.62 ± 4.0
	Arc2	100.0 ± 0.0	100.0 ± 0.0	96.94 ± 0.7	91.83 ± 2.5	99.75 ± 0.2	97.54 ± 0.9	78.54 ± 3.9	75.52 ± 4.3
+2	Arc1	100.0 ± 0.0	98.39 ± 0.0	73.63 ± 0.0	69.23 ± 0.0	99.61 ± 0.0	82.64 ± 0.0	69.06 ± 0.0	64.21 ± 0.0
	Arc2	100.0 ± 0.0	99.21 ± 0.0	75.86 ± 0.0	70.08 ± 0.0	99.43 ± 0.0	85.14 ± 0.0	69.32 ± 0.0	63.25 ± 0.0
+5	Arc1	78.64 ± 0.0	69.26 ± 0.0	64.90 ± 0.0	62.71 ± 0.0	75.92 ± 0.0	67.99 ± 0.0	64.79 ± 0.0	62.09 ± 0.0
	Arc2	77.09 ± 0.0	67.79 ± 0.0	64.21 ± 0.0	60.75 ± 0.0	74.64 ± 0.0	67.18 ± 0.0	63.89 ± 0.0	60.09 ± 0.0
−1	Arc1	100.0 ± 0.0	100.0 ± 0.0	97.50 ± 3.6	94.70 ± 5.0	99.43 ± 0.0	96.33 ± 0.6	78.51 ± 3.2	74.83 ± 4.4
	Arc2	100.0 ± 0.0	100.0 ± 0.0	97.36 ± 1.8	92.19 ± 1.7	99.66 ± 0.2	97.34 ± 1.0	78.72 ± 4.4	75.67 ± 4.9
−2	Arc1	100.0 ± 0.0	94.70 ± 3.5	74.87 ± 2.0	70.72 ± 2.8	99.69 ± 0.0	82.13 ± 1.0	71.50 ± 2.8	67.50 ± 3.6
	Arc2	100.0 ± 0.0	94.20 ± 3.2	75.90 ± 0.9	72.26 ± 1.6	99.58 ± 0.4	82.41 ± 1.0	72.37 ± 1.8	67.46 ± 3.5