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

Authors


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.

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