SU‐E‐T‐450: How Important Is a Reproducible Breath Hold for DIBH Breast Radiotherapy?

Abstract

Purpose:Deep inspiration breath hold (DIBH) for left‐sided breast cancer has been shown to reduce heart dose. Surface imaging helps to ensure accurate breast positioning, but does not guarantee a reproducible breath hold (BH) at DIBH treatments. We examine the effects of variable BH positions for DIBH treatments.Methods:Twenty‐Five patients with free breathing (FB) and DIBH scans were reviewed. Four plans were created for each patient: 1) FB, 2) DIBH, 3) FB_DIBH – the DIBH plans were copied to the FB images and recalculated (image registration was based on breast tissue), and 4) P_DIBH – a partial BH with the heart shifted midway between the FB and DIBH positions. The FB_DIBH plans give “worst case” scenarios for surface imaging DIBH, where the breast is aligned by surface imaging but the patient is not holding their breath. Students t‐tests were used to compare dose metrics.Results:The DIBH plans gave lower heart dose and comparable breast coverage versus FB in all cases. The FB_DIBH plans showed no significant difference versus FB plans for breast coverage, mean heart dose, or maximum heart dose (p >= 0.10). The mean heart dose differed between FB_DIBH and FB by < 2 Gy for all cases, the maximum heart dose differed by < 2 Gy for 21 cases. The P_DIBH plans showed significantly lower mean heart dose than FB (p = 0.01). The mean heart doses for the P_DIBH plans were < FB for 22 cases, the maximum dose < FB for 18 cases.Conclusions:A DIBH plan delivered to a FB patient set‐up with surface imaging will yield similar dosimetry to a plan created and delivered FB. A DIBH plan delivered with even a partial BH can give reduced heart dose compared to FB techniques when the breast tissue is well aligned.