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. 2013 Apr 23;40(5):051711. doi: 10.1118/1.4801899

Figure 6.

Figure 6

Dose distributions per field in the transverse plane for a representative patient illustrate the relative insensitivity of the robustly optimized plan (g)–(l) to setup uncertainties compared with the conventional PTV-based optimized plan (a)–(f). Panels (a)–(c) and (g)–(i) show dose distributions in nominal position; whereas the panels (d)–(f) and (j)–(l) show corresponding data with 3 mm superior shift. CTV1: left top big filled area; CTV2: two left small filled area abutting CTV1; CTV3: right filled area disconnected from CTV1. The shift perturbs the dose distribution in the PTV-based plan significantly [e.g., 32 and 27 Gy(RBE) isodose lines]. Field 1 appears to be most sensitive to perturbation presumably because it passes through most complex inhomogeneities. Robust optimization automatically reduces the contribution from this field. Furthermore, robust optimization considerably reduces high dose gradients within each of the three fields.