TABLE III.

Comparison of the total score and subscores for individual anatomic structures for the worst-case dose distributions for the PTV-based and robustly optimized plans. The subscores for the target (CTV/GTV) are calculated using Eq. 3a, while the subscores for the OARs are calculated using Eq. 3b. The total score is the sum of the subscore of the targets and OARs. The scores represent deviation from the individual constraints. If a dose constraint is met, the subs-score would be zero. Values of subscores depend on the values of the penalty parameters and on the number of points in the structure. Therefore, it is meaningful to compare subscores for different optimization methods only for the same structure. The penalty terms p and the dose constraints to the target and OARs are listed in Table TABLE IV..

Lung	Total	GTV	CTV	Heart	Cord	Esophagus	Normal lung
PTV-based solution	5.58 × 106	9.45 × 105	2.18 × 106	4.39 × 105	1.29 × 106	4.67 × 105	2.61 × 105
Robust optimization	3.86 × 106	6.47 × 105	1.83 × 106	3.60 × 105	4.15 × 105	3.77 × 105	2.27 × 105

Base-of-skull	Total	CTV	Optical chiasm	Brain-CTV	Brainstem	R temporal lobe	L temporal lobe	Whole brain
PTV-based solution	8.72 × 106	2.35 × 106	1.10 × 106	3.01 × 105	2.84 × 106	1.46 × 106	1.55 × 105	5.14 × 105
Robust optimization solution	7.21 × 106	2.16 × 106	1.16 × 106	2.59 × 105	1.90 × 106	1.18 × 106	1.06 × 105	4.47 × 105

Prostate	Total	CTV	Bladder	Rectum	Femoral heads
PTV-based solution	1.53 × 106	9.04 × 105	9.79 × 104	1.67 × 105	3.61 × 105
Robust optimization	1.07 × 106	5.04 × 105	8.76 × 104	1.57 × 105	3.23 × 105