[Radiation tolerance dose of the spinal cord following conventionally fractionated irradiation].

409 patients whose spinal cord were irradiated over 30 Gy with conventionally fractionated method were surveyed to study the relation between the dose of spinal cord and the incidence of radiation myelitis. Radiation myelitis was observed in 26 cases including 3 transverse myelitis ones. 5 year incidences of transverse myelitis calculated with life table method were approximately 0% at 40 Gy, 5% at 50 Gy, 10% at 60 Gy and 20% at 70 Gy. The radiation tolerance dose of the spinal cord was considered to be 50 Gy.