Trigger-Based Adaptive Planning to Reduce Bowel Dose in Patients Receiving Radiotherapy for Anal Cancer

Abstract

Dmean for heart, 2.9 Gy vs. 1.9 Gy (P < 0.001); Dmean, V20 and V30 for LAD, 12.6 Gy vs. 15.4 Gy (P < 0.001), 23.0% vs. 33.3% (P = 0.0049) and 2.0% vs. 24.7% (P < 0.001); Dmean, V20 and V30 for mLAD, 16.0 Gy vs. 21.1 Gy (P = 0.0014), 29.9% vs. 51.4% (P = 0.0040) and 0.5% vs. 31.1% (P < 0.001), respectively. The Dmean, V5 and V20 for the lungs and the Dmean for contralateral breast were significantly reduced in the 3D-CRT + EB plans (P < 0.001, for all). The doses to the LAD and mLAD tended to be higher in lateral cohort (upper outer and lower outer quadrants of breast) than in medial cohort (upper inner and lower inner quadrants of breast), while these doses were significantly reduced by the SIB-VMAT. Conclusion: Although 3D-CRT + EB technique can reduce the mean dose to the heart, the doses to LAD and mLAD can be significantly decreased by SIB-VMAT, which could be a benchmark for selecting the most appropriate irradiation technique in the patients with a potential risk of RICAD.