Exhibit Hall | Forum 7
Purpose: For locally advanced, non-small cell lung cancer (NSCLC) patients, recent trials have demonstrated the importance of limiting cardiac dose without sacrificing target coverage or significantly increasing lung dose. To accomplish these goals, a set of novel treatment planning strategies were designed and evaluated.
Methods: Three novel planning strategies were retrospectively implemented for a set of 20 previously treated, locally advanced, NSCLC patients originally prescribed to 60-66Gy that received a mean heart dose (MHD) ≥ 10 Gy. Of the planning strategies, the first was a multi-isocentric arc-based approach (Heart_MI) utilizing two isocenters at least 10cm apart longitudinally. The second was a non-coplanar, arc-based approach (Heart_NCP) that added a set of up to three large couch angles combined with short anterior arcs to a standard arc at a couch angle of 0. The last utilized a hybrid approach (Heart_HYBRID) that implemented the Heart_NCP strategy for 2/3 of treatment fractions and an opposite-opposed planning strategy angled to avoid the heart for the remaining fractions.
Results: Target coverage was maintained, and non-heart organ-at-risk doses were kept within prescribed levels. With respect to cardiac dose reduction, there were statistically significant decreases in Heart V30, V50, and mean dose for the Heart_MI (6.2 vs. 13.1% (p<0.001), 2.3 vs. 3.3% (p=0.01), 9.8 vs. 15.4 Gy (p<0.001), respectively), Heart_NCP (5.8 vs. 13.1% (p<0.001), 2.2 vs. 3.3% (p=0.02), 9.2 vs. 15.4 Gy (p<0.001), respectively), and Heart_HYBRID (5.0 vs. 13.1% (p<0.001), 2.3 vs. 3.3% (p=0.02), 7.9 vs. 15.4 Gy (p<0.001), respectively) strategies.
Conclusion: The Heart_NCP strategy represented the best compromise between cardiac dose reduction and maintaining plan quality metrics. Use of this strategy resulted in mean heart dose reductions of 37.6 + 12.9% (6.2 + 3.4 Gy) relative to original plans and brought mean heart dose below 10 Gy for 16 of 20 patients.
Funding Support, Disclosures, and Conflict of Interest: This work was supported by an Internal Mentored Grant. HFHS holds research agreements with Philips Healthcare and Varian Medical Systems.
Treatment Techniques, Lung, Heart