Accuracy of Setup in Deep-inspiration Breath-hold Irradiation Following Left Mastectomy Using Surface Imaging Guidance

Objective: To evaluate the setup accuracy of surface-guided postmastectomy radiotherapy (PMRT) under deep inspiration breath hold (DIBH).

Methods: Fourteen patients with left-sided breast cancer who underwent PMRT under DIBH were enrolled in this study. The setup error was defined as the difference in the position of clinical target volume between the planning computed tomography (CT) and the cone-beam CT acquired after surface-guided setup.

Results: The mean±standard deviation of setup error was 0.2±2.1 mm, -0.1±3.5 mm, and 0.4±2.1 mm in the anterior-posterior, superior-inferior, and right-left directions, respectively, and -0.1±0.8°, 0.5±0.9°, and 0.9±1.0° in the Yaw, Roll, and Pitch angles.

Conclusions: The setup accuracy of PMRT under DIBH using a surface-guided system was within 5 mm in 82% of all treatment fractions.