DISEASE CHARACTERISTICS: Histologically confirmed stage I, IE, or non-bulky II or IIE non-Hodgkin's lymphoma of one of the following subtypes: Diffuse large B-cell Mantle cell High grade B-cell, Burkitt's or Burkitt like Anaplastic large cell (B-cell phenotype only) Lymphoma must express CD20 All disease must be encompassable in a single radiation port (including any resected disease) Must have at least 1 of the following adverse prognostic features: Non-bulky stage II or non-bulky stage IIE disease Over 60 years of age Zubrod performance status of 2 Elevated serum LDH A new classification scheme for adult non-Hodgkin's lymphoma has been adopted by PDQ. The terminology of "indolent" or "aggressive" lymphoma will replace the former terminology of "low", "intermediate", or "high" grade lymphoma. However, this protocol uses the former terminology.