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.