Dosimetric Analysis of Fast-Forward Breast Radiotherapy Using 3D-Conformal Radiotherapy (3D-CRT) With Deep Inspiratory Breath Hold (DIBH)

Abstract

Introduction and aim Fast-forward radiotherapy (26 Gy in five fractions) has gained widespread acceptance for early-stage breast cancer due to its convenience and efficacy. However, in left-sided cases, there is a risk of radiation-induced cardiac and pulmonary toxicity due to the proximity of the heart and lungs. The voluntary deep inspiration breath-hold (vDIBH) technique increases thoracic volume and heart-chest wall distance, offering a non-invasive method to minimize organ-at-risk exposure. This study aimed to evaluate the dosimetric benefits of 3D-conformal radiotherapy (3D-CRT) combined with voluntary deep inspiration breath hold (vDIBH) in minimizing radiation dose to the heart and lungs during ultra-hypofractionated whole-breast irradiation in patients with left-sided breast cancer. Materials and methods We retrospectively analyzed 28 patients with left-sided breast cancer treated with 3D-CRT under vDIBH, receiving 26 Gy in five fractions. Target volumes and organs at risk (OARs) were contoured on vDIBH CT scans. Treatment planning was performed using tangential fields. Dosimetric parameters for the planning target volume (PTV), heart, ipsilateral lung, contralateral breast, and spinal cord were evaluated using dose-volume histograms (DVHs). Reproducibility of vDIBH was ensured by using in-room lasers, skin tattoos, and cine-mode imaging for intrafraction verification. Results Mean PTV V95% was 97.74±1.74%, with a mean dose of 26.61±0.25 Gy. The mean heart dose was 3.97±0.82 Gy, with V25% at 13.28±3.44%. Ipsilateral lung mean dose (D_mean) was 8.26±0.76 Gy, and V30% was 32.81±2.85%. Contralateral breast V5% was 5.19±7.06%. The spinal cord received a negligible dose (maximum dose {D_max}​​​​ 0.49±0.12 Gy). All patients tolerated vDIBH well, with no delays or treatment interruptions. Conclusion 3D-CRT with vDIBH offers a practical, reproducible, and cost-effective approach for delivering hypofractionated radiotherapy in left-sided breast cancer. It ensures excellent target coverage while significantly reducing radiation dose to critical structures, such as the heart and lungs, supporting its use as a standard practice even in resource-constrained settings.

Keywords: 3d-conformal radiotherapy (3d-crt); cardiac sparing; deep inspiration breath hold (dibh); dosimetric analysis; hypofractionated radiotherapy; left-sided breast cancer; voluntary breath hold.