(Saturday, 4/7/2018)
Room: Foyer
Purpose: To investigate if a correlation exists between treated breast volumes and heart doses for left-sided whole breast treatment in photon tangent field-in-field (FinF) and proton pencil beam scanning (PBS) therapy.
Methods: For thirty left-sided breast cancer patients, seventeen patients were treated with FinF modality using free-breathing (FB). The FinF plans were also generated on breath-hold (BH) CTs. Thirteen patients were treated with proton therapy with FB, and the PBS plans were created with one or two enface beams with a single field optimization technique. Volumes of whole breast PTV and heart mean dose were used for analysis.
Results: For the FinF modality treated with FB, when the breast PTVs were larger than 1000 cc, the average value of heart mean dose was 3.6 ± 0.4 Gy, and when the volumes were less than 1000 cc, the average value of heart mean dose was 2.0 ± 0.5 Gy. Differences between the two groups were statistically significant (p* = 0.036). For the FinF treated with BH, the average heart mean doses were 1.6 ± 0.2 and 1.0 ± 0.2 Gy for the PTVs larger and smaller than 1000 cc, respectively (p*=0.0237). For proton PBS, however, there were no differences of heart doses between the two groups (p=0.7). For all patients, the average heart mean doses were 3.0 ± 1.3, 1.3 ± 0.5 and 0.25 ± 0.17 Gy for photon FinF with FB, with BH, and proton PBS, respectively (p*<0.001).
Conclusion: For left-sided whole breast treatment with the photon FinF technique, patients with large breast volumes (> 1000 cc) are more likely to receive higher heart doses than patients with smaller breast volumes. FinF with BH or proton PBS can significantly lower heart doses. For proton treatment, the heart doses were minimal and patients’ breast volumes were not correlated with heart doses.
ePosters
Contact Email
