- Patients with a pleural effusion, which is a transudate, cytologically negative and non-bloody, are eligible if the radiation oncologist feels the tumor can be encompassed within a reasonable field of radiotherapy. Patients with exudative, bloody, or cytologically malignant effusions are not eligible; if a pleural effusion can be seen on the chest computed tomography (CT) but not on chest x-ray (CXR) and is too small to tap, the patient will be eligible; a pleural effusion appearing only after a thoracotomy or other invasive thoracic procedure was attempted will not make a patient ineligible