Impact of visual feedback on dose-volume histograms for organs at risk in postoperative radiotherapy with deep inspiration breath-holding for patients treated with breast-conserving therapy: a planning study.

Background: We evaluated the effectiveness of visual feedback (VF) on radiotherapy with deep inspiration breath-holding (DIBH), and reviewed the dose for organs at risk (OARs).
Methods: Respiratory motions during DIBH for 15 s were monitored during planning computed tomography (CT)-scanning and simulation for 40 patients after breast-conserving surgery from June 2007 to February 2008. For 22 of 40 patients, a goggle-type liquid crystal display monitor was used for VF. The opposing tangential field was planned. The prescribed dose was 50.0 Gy in 25 fractions.
Results: The mean differences of the chest wall respiratory movement in DIBH between planning CT-scanning and simulation were 4.7 ± 2.6 mm for the patients without VF and 1.0 ± 0.9 mm for those with VF (p < 0.01). The mean chest wall excursion as a whole in DIBH using VF (2.0 ± 1.0 mm) was smaller than in those without VF (4.1 ± 2.4 mm) (p < 0.01). According to reproducibility and stability parameters, 4 mm was added as a posterior margin to the clinical target volume for RT with VF, and 10 mm for those without VF. The mean heart doses were 1.3 ± 0.5 Gy with VF and 2.4 ± 1.1 Gy without VF (p < 0.01). Mean dose and max dose of right breast were significantly reduced in procedures with VF use vs. in those without VF (p < 0.01 and < 0.01, respectively).
Conclusions: VF increases the accuracy of postoperative radiotherapy with DIBH, and also helps reduce the dose for OARs.