Locoregional breast radiotherapy including IMN: optimizing the dose distribution using an automated non-coplanar...

Area of Science:

• Radiation Oncology
• Medical Physics
• Oncology

Background:

• Volumetric Modulated Arc Therapy (VMAT) improves target coverage and organ sparing in left-sided breast cancer radiotherapy compared to 3D-CRT.
• Conventional VMAT (cVMAT) can increase radiation doses to contralateral normal tissues.
• Non-coplanar VMAT (ncVMAT) is investigated to address dose escalation in contralateral tissues.

Purpose of the Study:

• To evaluate the efficacy of a novel non-coplanar VMAT (ncVMAT) technique.
• To compare ncVMAT with conventional VMAT (cVMAT) and 3D-CRT for locoregional radiotherapy in left-sided breast cancer.
• To assess the impact of ncVMAT on dose distribution to the target and organs at risk, particularly contralateral tissues.

Main Methods:

• CT scans from 20 patients with left-sided breast cancer were used for treatment planning.
• Three treatment plans were generated: 3D-CRT, cVMAT, and ncVMAT, with a prescription dose of 40.05 Gy.
• ncVMAT incorporated an additional sagittal plane arc alongside the standard axial plane arc used in cVMAT.

Main Results:

• Both VMAT techniques achieved more conformal and homogeneous target doses than 3D-CRT.
• ncVMAT significantly reduced doses to the heart and ipsilateral lung compared to cVMAT and 3D-CRT.
• ncVMAT lowered contralateral breast and lung doses compared to cVMAT, avoiding high doses (>30 Gy) to these areas.

Conclusions:

• ncVMAT offers superior sparing of the heart and ipsilateral lung compared to cVMAT and 3D-CRT.
• The ncVMAT technique effectively reduces radiation dose to contralateral tissues, achieving levels comparable to 3D-CRT for the contralateral breast.
• ncVMAT represents a promising advancement in radiotherapy for left-sided breast cancer, enhancing safety and potentially reducing side effects.