TABLE 2.

The Percent Standard Deviation Across the Calculated RBE Values as a Result of Statistically Varying Input Parameters by ± 5%, 10%, 20%, and 40% at the $1-\text{σ}$ Level^a

Parameter	${\alpha }_x$				${\beta }_x$				${\alpha }_0$				$R_n$				$r_d$				$y^{\ast }$
Variation (%)	±5	±10	±20	±40	±5	±10	±20	±40	±5	±10	±20	±40	±5	±10	±20	±40	±5	±10	±20	±40	±5	±10	±20	±40
$\text{σ}$ MKM (%) $\text{σ}$ SMKM (%)	1.7 1.7	3.4 3.5	6.9 7.1	14 14	0.6 0.6	1.1 1.2	2.5 2.6	7.1 7.4	0.7 0.7	1.3 1.4	2.7 2.8	5.3 5.5	0.7 0.7	1.3 1.4	2.9 3.0	9.1 9.5	3.7 3.7	8.1 7.9	19 20	79 62	2.2 2.3	4.4 4.5	8.8 9.1	18 19
Parameter	${\alpha }_x$				${\beta }_x$				${\Sigma }_x$				$z_{F,x}$				${\Sigma }_p$				$z_{F,p}$
Variation (%)	±5	±10	±20	±40	±5	±10	±20	±40	±5	±10	±20	±40	±5	±10	±20	±40	±5	±10	±20	±40	±5	±10	±20	±40
$\text{σ}$ RMF (%)	2.2	4.2	8.8	18	1.4	2.9	5.8	16	5.4	10	25	114	0.0	0.0	0.1	0.1	5.1	10	20	40	0.0	0.1	0.1	0.2
	${\alpha }_x$				${\beta }_x$				$K{E}_i$
Variation (%)	±5	±10	±20	±40	±5	±10	±20	±40	±5	±10	±20	±40
$\text{σ}$ LEM (%)	1.6	3.4	6.7	14	1.8	3.8	7.9	23	0.8	1.9	3.7	9.9

Note. The results are presented for the SOBP region (>0.5 cm from the proximal or distal edge), where the physical dose is normalized to 2 Gy throughout.

^aThe reference parameters are in white, whereas the carbon-specific parameters are shaded in gray. For each input parameter, the variation threshold that approximately represents $1-\text{σ}$ uncertainty (estimated from the spread in literature-reported values) is shaded in yellow.