使用廣義等效均勻劑量(gEUD)為優化基礎的劑量體積目標之雙邊乳癌強度調控放射治療計劃

Purpose: To compare the planning performance between dose-volume-based IMRT plans (DV-based IMRT plan, (DV-plan) ) and DV-plan with generalized equivalent uniform dose (gEUD) optimization (DV-gEUD-based IMRT plan, (DV-gEUD-plan) ) on bilateral breast cancer (BBC).Materials and Methods: Six consecutive BBC patients (staged: T2-T4) were planed using the planning system of the Pinnacle^3 (version 8.0 m, Philips, Fitchburg, WI) to compare the performance of DV-and DV-gEUD plans. The plan was delivered on a Varian 21 EX Linac (Varian Medical Systems, Milpitas, CA) equipped with a 120-leaf multileaf collimator. The prescribed doses were 50.4 Gy/28 fractions to the planned target volume (PTV). The dosimetric parameters used included the conformity index (CI), homogeneity index (HI) and tumor control probability (TCP) for the PTV; and V(subscript 20Gy) and V(subscript 30Gy) for the total lung and heart, respectively; and mean dose, normal tissue complication probability (NTCP) for the both OARs. The planning delivery accuracy was checked.Results: Both techniques fulfilled the objectives on target coverage. A comparable CI and HI of the PTV were observed on both plans. For the OARs, a significantly superior normal tissue sparing was observed in DV-gEUD-plan. The DV-gEUD-plan has smaller mean dose of lung and heart, V(subscript 20Gy) of lung, and V(subscript 30Gy) of heart (p＜0.05) with respect to the DV-plan. Both plans presented a high QA pass rate (＞95.5%) of the T(subscript 3mm. 3%) criterion.Conclusions: A better plan (DV-gEUD-plan) can be obtained through a combination of DV-and gEUD-based objective function, This hybrid approach can reduce the number of trial and error in DV-plan processing while retaining a better dose distribution which gEUD-plan can provide.