Inclusion Criteria:

1. Patients must have undergone radical pleurectomy/decortication and will be enrolled after surgery.
2. Patients must have had a CT/PET scan prior to surgery
3. Patients will have baseline pulmonary function tests and a quantitative V/Q scan prior to radiation therapy, and then pulmonary function tests one month and three months after the completion of radiation. To be conservative, we will assume that the ipsilateral lung will be nonfunctional after radiation treatment. Therefore, our inclusion criteria for baseline pulmonary function tests are very similar to those that we require prior to an extrapleural pneumonectomy, and are as follows:
4. FEV1 >/= 30% of predicted postoperative (ppoFEV1) (as if the patient underwent a pneumonectomy) based on the following formula using the quantitative V/Q scan: - Predicted post-resection FEV1 = FEV1 x % perfusion to uninvolved lung from the quantitative V/Q scan report.
5. DLCO > 35% predicted
6. Patients must be able to lie flat for the duration of the treatment planning sessions and treatment.
7. Patients must be adequately recovered from surgery and prepared to begin radiation therapy 18 weeks after pleurectomy/decortication. We anticipate that most patients will be ready for radiation simulation between 8-16 weeks after surgery.
8. Patients who have received induction chemotherapy will be included in the study.
9. **Note that 2- 6 represent standard criteria for the delivery of radiation therapy after pleurectomy/decortication, and are not novel criteria for the purposes of this protocol.
10. Age >/= 18.
11. All women of childbearing potential (A woman of child-bearing potential is a sexually mature woman who has not undergone a hysterectomy or who has not been naturally postmenopausal for at least 12 consecutive months [i.e., who has had menses at any time in the preceding 12 consecutive months]) and male participants must practice effective contraception (abstinence, oral, injectable, or implantable hormonal contraceptive; tubal ligation; intra-uterine device; barrier contraceptive with spermicide; or vasectomized partner) throughout the study.
12. Calculated glomerular filtration rate of 80 mL/min/1.73m^2 with at least 40% of renal contribution from the kidney contralateral to the treated hemithorax, as demonstrated by a pre-radiation renal scan.

Exclusion Criteria:

1. Patients having previous radiation therapy to the low neck, thorax or upper abdomen, unless the previous radiation therapy is clearly out of the current radiation field, as determined by the treating physician
2. Patients with metastatic disease.
3. Patients with any of the following conditions: 1) concomitant malignancies other than squamous cell or basal cell carcinoma of the skin, 2) Carcinoma in situ of the cervix, 3) Uncontrolled acute congestive heart failure defined by New York Heart Association Class III or IV. 4) Patients that have NCCN classified low-risk prostate cancer