Abstract

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 (D_max), mean ± SD was 110 ± (1.4) and the minimum point dose (D_min), 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 D_max, mean ± SD was 111 ± (5.0) and the D_min, 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.

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