Abstract 206P
Background
Atrial fibrillation (AF) is awell-documented potential side effect of thoracic radiotherapy (RT). Evidence indicates that the pathological cardiac tissue contributing to AF is often found within the pulmonary veins (PV). Despite this, these vessels are not currently classified as organs at risk in RT planning. This study aimed to evaluate the radiation dose distribution to the PV using three-dimensional conformal radiotherapy (3DCRT) and volumetric modulated arc therapy (VMAT) and to explore the feasibility of sparing the PV.
Methods
Forty patients who had previously undergone 3DCRT for lung cancer were retrospectively re-planned using VMAT with pulmonary vein (PV) sparing. The median prescribed dose was 58.8 Gy [range: 44–66 Gy]. The PV were delineated retrospectively based on M. Walls’ pulmonary vein atlas. VMAT and 3DCRT plans were compared by analyzing mean dose (Dmean), maximum dose (Dmax), V20Gy, V30Gy, V46Gy, V55Gy, and V60Gy. The Wilcoxon signed-rank test was used for statistical analysis, a p value less than 0.05 was considered statistically significant.
Results
Compared with 3DCRT, VMAT significantly reduced mean doses to the right PV including Dmean (31,6 Gy versus 28,4 Gy, p=0,03), V30Gy (40,8 Gy versus 48,4 Gy, p=0.002), V46Gy (34,4 Gy versus 41 Gy, p=0.002), V55Gy (23 Gy versus 31,7 Gy, p=0.02) and V60Gy (15,3 Gy versus 22,5 Gy, p=0.04). Dmax to the right PV and doses to the left PV were not improved in patients treated with VMAT compared with 3DCRT.
Conclusions
VMAT treatment with pulmonary vein (PV) sparing has demonstrated a significant reduction in PV doses compared to the 3DCRT technique. Protecting the PVs may help decrease the risk of atrial fibrillation (AF). Consequently, the PVs should be recognized as organs at risk in thoracic radiotherapy planning, and efforts to spare them should be prioritized.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.