This study aimed to investigate the optimal conditions and clinical efficacy of dose expansion techniques using skin flash (SF) and virtual bolus (VB) in intensity-modulated radiotherapy (IMRT) planning for breast cancer. Twenty patients who underwent adjuvant radiotherapy after left breast-conserving surgery were retrospectively analyzed, and dose indices and delivery accuracy were evaluated according to different margin expansion methods and thicknesses. Changes in breast shape during fractionated treatment were assessed using treatment images to determine appropriate margin sizes. Dosimetric comparisons between the Anisotropic Analytical Algorithm (AAA) and Acuros XB (AXB) were conducted using phantom measurements. The AXB algorithm provided more accurate dose calculations in the skin and built-up regions than the AAA algorithm under various conditions. SF achieved better target coverage and organ-at-risk sparing than VB, despite requiring up to 8% more monitor units (MU). However, larger dose margins (≥20 mm) in SF plans resulted in split fields, increased MU, and reduced gamma pass rates, which compromised plan quality. Implementing dose-expansion techniques in breast IMRT can enhance dose coverage and compensate for clinical setup errors. Based on our findings, using the SF technique with a 5–10 mm margin and the AXB algorithm offers an effective balance between target coverage, skin dose accuracy, and treatment efficiency. Individual patient anatomies and setup variability should be carefully considered when selecting margin sizes and planning strategies to achieve optimal outcomes.
Kim et al. (Fri,) studied this question.