Dosimetric Effect on Breast Cancer Patients Treated with Volumetric-Modulated Arc Therapy: Single Institutional Experience

Objective: To examine the dosimetric effect of Breast Cancer (BC) patients Receiving Radiotherapy (RT) with Volumetric-Modulated Arc Therapy (VMAT). Methodology: This retrospective study enrolled 53 BC women, treated with VMAT between Oct 2013 and Nov 2018. The fractionation was within 40 Gray-50 Gray (Gy) in 15-25 fractions. Dosimetric parameters, Homogeneity Index (HI), Conformity Index (CI), Mean Heart Dose (MHD), and doses to the Ipsilateral Lung (IPL) and Mean Contralateral Breast (MCB) were analyzed. Results: Dosimetric results for 50 Gy/25 Fx showed, D98% (mean ? standard deviation) was 47.5? 0.8 Gy, PTV D2% was 53 +/- 0.4 Gy, and D50% was 51 +/- 0.3 Gy. The maximum point dose (Dmax), mean +/- SD was 110 +/- (1.4) and the minimum point dose (Dmin), was 72 +/- (9.1). The HI and CI were 0.11 +/- 0.02 and 0.1 +/- 0.07. The average MHD was 10.6 +/- 3.3 Gy, and the MCB dose 4.5 +/- 1.4 Gy, IPL V20Gy 31.5 +/- 4.7%. For hypofractionated dose, D98% (mean dose +/- SD) was 41 +/- 1.6 Gy, PTV D2% was 45 +/- 01.9 Gy and, D50 was 43 +/- 1.8 Gy. The Dmax, mean +/- SD was 111 +/- (5.0) and the Dmin, mean +/- SD was 75 +/- (11). The HI and CI were 0.1 +/- 0.02, and 0.1 +/- 0.34. The average MHD was 10.5 +/- 3.55 Gy, MCB 3.7 +/- 1.4 G, IPL V20 Gy 31.5 +/- 4.7%. Conclusion: VMAT is favorable with complex patient anatomy or when the internal mammary region is included.