4D CBCT and Intrafractional Imaging for the Determination of the Most Representative 4D Simulation Planning Technique for Lung SBRT Technique Patients

Inclusion Criteria: * Age ≥ 18 years. * Ability to provide informed written consent in either English or Spanish. * Patients with cancer or presumed cancer involving the lung (primary or secondary) planned to undergo lung SBRT technique or IMRT technique with an SBRT setup in 10 or fewer fractions. Exclusion Criteria: * Current pregnancy, as this is a contraindication to receiving radiation therapy. * Patients to be treated to multiple targets concurrently. * Any condition or history as evidenced by patient record and/or self-report that, in the opinion of the investigator, would interfere with adherence to the prescribed pattern of radiation therapy. * Poor lung function, as judged by the prescribing radiation oncologist, sufficiently limiting to make the patient not a candidate for 4D imaging (for example major differences between the 4D and free-breathing CT scan).