Dosimetric Study Comparing 3D Conformal Radiotherapy (3D-CRT), Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) in Hypofractionated One-Week Radiotherapy Regimen in Breast Cancer

Abstract

IntroductionRecently, the one-week hypofractionated radiotherapy regimen (26 Gy in 5 fractions) for adjuvant breast radiotherapy has been shown to be non-inferior to other hypofractionated regimens (15-16 fractions). The aim of the present dosimetric study is to compare Intensity Modulated Radiotherapy (IMRT), Volumetric Modulated Arc Therapy (VMAT) and 3D Conformal Radiotherapy (3D-CRT) for a one-week hypofractionated radiotherapy regimen (26 Gy in 5 fractions) for adjuvant breast radiotherapy. MethodsA total of 30 patients with histologically proven invasive carcinoma of the breast after breast conservation surgery (BCS) or modified radical mastectomy (MRM) were considered for in silico planning study. The dose prescription used was 26 Gy in 5 fractions as used in the FAST Forward protocol. Targets were contoured according to standard guidelines. The heart, ipsilateral lung, and contralateral breast were contoured as organs at risk. ResultsPlanning Target Volume (PTV) coverage: For IMRT, VMAT and 3D-CRT, respectively, the volumes that received at least 95% of the prescription dose (V 95 ) were 95.7 ± 2.12, 92.47 ± 3.83, 90.87 ± 5.13; mean PTV doses (D mean ) were 26.1 ± 0.6, 25.7 ± 0.7, and 28 ± 4.39 (3D-CRT has higher D mean compared to other techniques). Maximum PTV doses (D max ) were 28.23 ± 0.72, 28.73 ± 0.64, and 29.8 ± 1.03. IMRT had a better V 95 coverage and conformity index.Organs At Risk (OARs): The volumes that received at least 25% of the prescription dose (V 25 ) of the heart were 3.41 ± 4.7, 1.8 ± 2.02 and 4.3 ± 6.98 in IMRT, VMAT and 3D-CRT, respectively. The volumetric (V 25 ) comparison of heart dose in left-sided breast cancer was significantly different between VMAT and 3D-CRT (p=0.04, Wilcoxon signed-rank test). The volume that received at least 5% of the prescription dose (V 5 ) was less than 25% in the 3D-CRT plan (12.55).

Evaluation of Heart Substructures as a Function of Dose and Radiation-Induced Toxicities in Left-Sided Breast Cancer Radiotherapy

“…Te dosimetric data from our study can be compared with the study conducted on 30 patients by Ahmad et al which compared conformal and modulated plans. Te conclusions that emerged from the study were that low doses remain a dosimetric concern for intensity-modulated techniques suggesting a lower V 5 for conformal plans [8]. Te low dose parameter (V 5 ) for heart in our study showed a smaller value for conformal plans (18.79% 3DCRT, 21.16% IMRT, and 19.89% VMAT) with no statistically signifcant diference between conformal and modulated plans (P > 0.05).…”

“…Others conducted comparative studies between conformal and modulated radiotherapy techniques suggesting that dosimetric advantages depend on the feld geometry: standard tangents, tangential intensity-modulated radiotherapy (IMRT), full arcs volumetric-modulated arc radiotherapy (VMAT), and 2 arcs divided into 2 sections VMAT or multiple arcs (VMAT) [7,8]. For instance, Jin et al evaluated the diference between the tangential wedged-felds technique, two types of IMRT (tangential and 7 felds IMRT) and VMAT.…”

Most Appropriate Radiation Therapy Techniques for The Breast Cancer Treatment: Dosimetric Analysis of Three Different Radiation Therapy Methods

“…In another similar study, Ahmad A. et al compared VMAT, IMRT and 3D CRT with a one-week hypofractionated radiotherapy regime (26 Gy in 5 fractions) for adjuvant breast radiotherapy. Authors concluded that IMRT and VMAT techniques are feasible and can achieve better dosimetric goals for target and OARs though minimizing the area achieving low dose remains to be a dosimetric concern for VMAT[27].…”