<qa>  What is not required if no clinical suspicion or evidence of CNS involvement is found?- Active CNS lymphoma within two weeks of registration. Patients with a history of CNS involvement must have adequate treatment as defined by at least two negative spinal fluid assessments separated by at least one week. Otherwise LP is not required if no clinical suspicion or evidence of CNS involvement. Patients who have received cranial radiation therapy must still be eligible to receive total lymphoid irradiation to 7 Gy. 