Comparison of VMAT, Field in Field, Inverse IMRT, and Helical Tomotherapy Planning in Bilateral Synchronous Breast Cancer: A Case Study

This study aims to compare the technical feasibility and benefits of four different planning techniques, VMAT, helical tomotherapy, IMRT and Field in Field, for synchronous bilateral breast cancer patients. In this study, two patients with early bilateral breast cancer after breast conservation surgery were planned for radiotherapy. Three different treatment planning techniques were generated for each patient on the Eclipse treatment planning system, and both patients were planned on the Tomotherapy planning system. For planning target volumes (PTVs), the mean doses, values of D2, D98, conformity index and homogeneity index were reported. For the organs at risk, the analysis included the mean dose and VXGy, depending on the organs (lungs, heart). In all techniques used in this study, there was no difference in D98% tPTV, while the lowest D2% was seen in HT plans. HT was the best in conformity and homogeneity index. For Pat#1 and Pat#2, the mean dose (Dmean) to total lungs were 10.8;10.5, 11;13,5, 10.3;10 and 12.2;14.5 Gy for FinF, IMRT, HT and VMAT, respectively and the mean dose to the heart was 5.6, 5.7, 7.9 and 6.8Gy (Pat#1); 4.6, 8, 8.4 and 6.3Gy (Pat#2), respectively. Heart volume at high doses (V25Gy, V30Gy) was approximately 80% lower for HT and 90% lower for VMAT than for FinF. The highest total motor unit value (14555 MUs) was seen in HT plans. Among the SBBC radiotherapy treatment plans, the HT plans improved the PTV dose coverage and dose homogeneity with improved sparing of lungs and heart.