 This phase II study will investigate the use of palonosetron in the efficacy of prophylaxis or rescue of single or multiple fraction radiation induced nausea and vomiting. This prospective study employs a parallel arm design, allowing for inclusion of patients with pre-existing nausea and vomiting versus no current nausea or vomiting. Eligible patients receiving radiotherapy known to have a low or moderate emetogenic risk will receive every other day dosing of 0.5 mg palonosetron for the length of treatment. Nausea, vomiting, use of rescue medication, and impact on quality of life will be monitored during and after radiation treatment completion. 