Radiation tolerance of the cervical spinal cord.

A total of 109 patients were studied after receiving radiation therapy that included a dose to the spinal cord. In addition to irradiation of the primary site, 59 patients received radiation to the lower neck. Transverse myelopathy developed in three patients; all three had been treated with fields to the lower neck. The dose to the spinal cord at the site of junctional fields was thought to be considerably higher because of the beam divergence from multiple fields employed. The authors stress that prolonged fractionation of treatment, fixation of the head during treatment, precise dosimetry, and close surveillance of the patient are important factors in avoiding radiation myelitis. The authors also stress the importance of controlling divergence of multiple beams by employing appropriate shields.