HEARTS Trial for Thoracic Cancers

Inclusion Criteria: * Age \> 18 years at the time of consent. * Dosimetric eligibility criteria met using endpoints from QUANTEC (\>10% of heart receives \> 25 Gy) as determined through rapid auto-planning * Participants with histologically or cytologically proven AJCC, 8th edition including: * Stage IIB, IIIA, IIIB, IIIC, or IV non-operable non-small cell lung cancer * Limited stage small cell lung cancer, once daily treatment (excluding twice per day fractionation schemes). Stage I-III N0-2 disease esophageal/esophagogastric cancer * Stage II or III thymoma/thymic carcinoma * Other cancers in the thoracic region that meet the dosimetric and other clinical trial criteria, for example lymphoma sarcoma. * Participants must have a course of daily fractionated RT planned of at least 15 treatment fractions, typically ranging from 1.8 to 4 Gy/fraction Exclusion Criteria: * Definitive clinical or radiologic evidence of metastatic disease with life expectancy \<12 months * Prior thoracic radiotherapy significantly overlapping the heart region * Contraindications to MRI * Severe, active co-morbidity defined as follows: New York Heart Association Functional Classification III/IV are not eligible.