Abstract # 2829 Optimizing the Cardiac and Pulmonary Dose: A Comparison of IMRT Photon and 3-D Proton Treatment Planning for Distal Esophageal Cancer

Presenter: Crowley, Elizabeth

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Eight patients with distal esophageal/GE junction cancer were identified. The clinical tumor volume (CTV) receiving the initial 45 Gy was defined by the CT‐based gross tumor volume (GTV) with a 3‐5 cm cranial‐caudal and a 1‐2 cm radial expansion. A cone down boost of 5.4 Gy was added to the GTV plus a customized margin yielding a final dose of 50.4 Gy. For photon IMRT plans, planning tumor volume (PTV) expansions were individualized based on 4D‐CT. For proton plans, residual motion was assessed with 4D‐CT to determine the dosimetric “smearing” necessary to account for the changing tissue heterogeneity (lung vs. soft tissue) due to diaphragmatic excursion. The treatment planning goals were, in order of priority: 1) spinal cord max dose < 45 Gy; 2) > 95% of the PTV covered by the prescription isodose line; 3) lung dose restricted to a combined V20 < 30% and a mean lung dose of 20 Gy; 4) heart dose restricted to V40 < 20%; and 5) global hot spot of less than 15%.