Mesothelioma is an incurable cancer involving the lining of the lung. Patients usually suffer progressive symptoms of shortness of breath and chest pain, until they ultimately succumb to the disease. While a very small number of patients qualify for aggressive treatment with surgery, chemotherapy and radiation, and enjoy long-term survival, the vast majority of patients have incurable disease. The treatment options currently available, including chemotherapy and radiation treatment, are only modestly effective at alleviating symptoms and improving life expectancy. This trial explores the use of new radiation technology (tomotherapy), to treat mesothelioma more aggressively than has been possible before. Tomotherapy's ability to treat unusual shaped tumours, particularly when they are wrapped around sensitive normal tissues (the lung), enable higher doses of radiation to be used and this may improve its effectiveness. We will treat 17 patients with tomotherapy and assess the breathing, symptoms, and quality of life of the patients before and after treatment