Table 1.

Treatment planning system beam modeling parameters requested via IROC Houston surveys and their range of dose effects (based on the reported spread in values), as previously determined by phantom dose calculations, for a common base Varian linac model equipped with Millennium120 MLC (e.g. Trilogy, 2100iX, etc.) using 6 MV photons [13,20].

TPS Parameter	Estimated Dose Effects
	2.5th Percentile		10th Percentile		90th Percentile		97.5th Percentile
	Parameter Value	Dose Effect (vs. 50th percentile)	Parameter Value	Dose Effect (vs. 50th percentile)	Parameter Value	Dose Effect (vs. 50th percentile)	Parameter Value	Dose Effect (vs. 50th percentile)
Eclipse AAA
Effective Target Spot Size X and Y [mm]	0.0000	0.0%	0.0000	0.0%	0.5000	0.0%	1.0000	0.0%
MLC Transmission Factor	0.0118	−1.1%	0.0134	−0.7%	0.0200	+0.8%	0.0200	+0.8%
Dosimetric Leaf Gap [cm]	0.1000	−3.6%	0.1388	−1.5%	0.2000	+1.2%	0.2300	+2.8%
RayStation
Primary Source X Width and Y Width [cm]	0.05000	0.0%	0.04000	0.0%	0.09700	0.0%	0.12345	0.0%
MLC Transmission	0.0070	−4.0%	0.0070	−4.0%	0.0250	+2.3%	0.0250	+2.3%
Tongue and Groove [cm]	0.0100	+1.1%	0.0100	+1.1%	0.0500	−0.3%	0.0500	−0.3%
Leaf Tip Width [cm]	0.1770	−1.6%	0.1860	−1.4%	0.5000	+1.9%	0.5000	+1.9%
MLC Position Offset [cm]	0.0000	−3.6%	0.0000	−3.6%	0.1160	+6.7%	0.1160	+6.7%
MLC Position Gain	0.0000	0.0%	0.0000	0.0%	0.0150	0.0%	0.0150	0.0%
MLC Position Curvature [1/cm]	0.0000	0.0%	0.0000	0.0%	0.0010	+0.2%	0.0010	+0.2%