Dosimetric comparison of three different radiotherapy techniques (3DCRT, ECOMP & VMAT) for breast irradiation

Background: The aim of this study was to compare the treatment plans of three techniques namely three-dimensional conformal radiotherapy (3DCRT), Electronic tissue compensator (ECOMP) based planning and Volumetric Modulated Arc Therapy (VMAT). Material and Methods: The planning goal was set to cover 95% of the planning target volume with 95% prescription dose for the dose plan of 40 Gy in 16 fractions. Treatment techniques with improved dose homogeneity, optimum skin dose, lung dose (V20Gy) and contralateral breast dose were used as the criteria to select the optimized treatment plan. The treatment planning time and the number of monitor units (MU) required to execute the plan were also taken into consideration. Result: PTV coverage (V95%) for the patient of ca-right breast and the ca-left breast was superior in VMAT plans. Ipsilateral lung (V5Gy %) showed significant dose reduction in ECOMP plans compared to 3DCRT and VMAT plans. Similarly, for the heart and contralateral lung, the mean doses were least in ECOMP plans. Dose homogeneity Index (HI) and Dose conformity Index (CI) was better in ECOMP plans compared to 3DCRT, but VMAT plans were superior to both the other techniques. The skin surface dose was less in VMAT plan. Conclusion: VMAT has high CI as well as HI but at the cost of higher OAR doses (lung and heart) and large treatment planning time. For a busy center, ECOMP can be a good choice of treatment technique which can optimize the OAR doses and treatment planning time but for dose homogeneity and conformity, VMAT is superior to others.