. 2020 Mar 9;21(4):42–50. doi: 10.1002/acm2.12844

TABLE 3.

Comparison of the dosimetric parameters for nasopharyngeal tumor cases with RBE = 1.1 (equal to the treatment plan) and the variable RBE.

Case	Tissue	Dosimetric parameter	PTV‐based opt. (cGy [RBE])			Robust opt. (cGy [RBE])
Case	Tissue	Dosimetric parameter	RBE = 1.1	Variable RBE	$Δ D_{99}, Δ D_{max}$ [%]	RBE = 1.1	Variable RBE	$Δ D_{99}, Δ D_{max}$ [%]
CaseA	CTV	D ₉₉	7220	7534/6987	4.4/−3.3	7223	7510/6980	4.0/−3.4
		D _98,worst	–	–		7040	–
	PTV	D ₉₅	7236	–		–	–
	Brainstem	D _max	3893	4947	15.2	4029	4675	9.0
	Spinal cord	D _max	4199	5593	19.5	4199	4947	10.5
CaseB	CTV	D ₉₉	7215	7531/6994	4.4/−3.1	7211	7585/7052	5.2/−2.2
		D _98,worst	–	–		7042	–
	PTV	D ₉₅	7232	–		–	–
	Brainstem	D _max	4505	5967	20.5	4573	5355	11.4
	Spinal cord	D _max	2907	3893	13.8	2805	3417	8.6
CaseC	CTV	D ₉₉	7198	7504/6960	4.3/−3.3	7221	7589/7028	5.2/−2.7
		D _98,worst	–	–		7039	‐
	PTV	D ₉₅	7215	–		–	–
	Brainstem	D _max	4845	6001	16.2	4845	5797	13.3
	Spinal cord	D _max	3553	4743	16.7	3281	4233	13.3
CaseD	CTV	D ₉₉	7225	7531/7055	4.3/−2.4	7225	7463/6953	3.3/−3.8
		D _98,worst	–	–		7157	–
	PTV	D ₉₅	7191	–	16.7	–	–	13.3
	Brainstem	D _max	3859	5015	16.2	3689	4675	13.8
	Spinal cord	D _max	3077	4199	15.7	3043	3995	13.3

As for the dosimetric parameters for the CTV calculated with the variable RBE, the results of ${(α / β)}_{x} = 3$ and ${(α / β)}_{x} = 12$ are shown in the left and right sides in the same cell, respectively. Values of the dosimetric parameters are rounded to the nearest 0.1 cGy.

CTV, clinical target volume; PTV, planning target volume; RBE, relative biological effectiveness.