Comparison of Techniques for Involved-Site Radiation Therapy in Patients with Lower Mediastinal Lymphoma

Abstract Introduction Patients with lower mediastinal lymphoma (LML) benefit dosimetrically from proton therapy (PT) compared with intensity-modulated radiotherapy (IMRT). The added dosimetric benefit of deep-inspiration breath-hold (DIBH) is unknown; therefore, we evaluated IMRT versus PT and free-breathing (FB) versus DIBH among patients with LML. Materials and Methods Twenty-one patients with LML underwent 4-dimensional CT and 3 sequential DIBH scans at simulation. Involved-site radiotherapy (ISRT) target volumes and organ-at-risk contours were developed for both DIBH and FB scans. FB-IMRT, DIBH-IMRT, FB-PT, and DIBH-PT plans were generated for each patient for comparison. Results The median difference in lung volume between the DIBH and FB scans was 1275mL; the average difference in CTV volume was 5.7mL. DIBH-IMRT produced a lower mean lung dose (10.8Gy vs 11.9Gy, p Conclusions Among patients with LML, DIBH (IMRT or PT) improved lung dosimetry over FB but had little impact on MHD. PT (DIBH and FB) significantly reduced lung, heart, esophagus, and non-target body dose compared with DIBH IMRT, potentially reducing the risk of late complications.