RecruitingPhase 2Radiation therapyA Study of Intensity-Modulated Pleural Radiation Therapy (IMPRINT) in People With Thymic Cancer That Has Spread to the Lining of the Lungs and ChestThe researchers are doing this study to find out whether hemithoracic intensity-modulated pleural radiation therapy (IMPRINT) is a safe treatment that causes few or mild side effects in people with pleural metastases from thymic malignancies. The researchers will also look at whether hemithoracic IMPRINT is effective against participants' cancer.