Neutron RBE for Primate Spinal Cord Treated with Clinical Regimens

• Published in: Radiation research 1992-02, Vol.129 (2), p.212-217
• Main Authors: Schultheiss, Timothy E., Stephens, L. Clifton, Ang, K. Kian, Jardine, John H., Peters, Lester J.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Biological effects of radiation; Dose response relationship; Dose-Response Relationship, Radiation; Fast Neutrons; Fundamental and applied biological sciences. Psychology; Ionizing radiations; Lesions; Macaca mulatta; Neutrons; Photons; Radiation dosage; Radiation dose response relationship; Radiotherapy; Radiotherapy, High-Energy - adverse effects; Relative Biological Effectiveness; Spinal cord; Spinal cord diseases; Spinal Cord Diseases - etiology; Spinal Cord Injuries - radiotherapy; Tissues, organs and organisms biophysics
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3578159

The RBEs of high-energy neutrons given in 9 or 12 fractions for cervical spinal cord injury in rhesus monkeys was determined using photons at 2.2 Gy per fraction as the reference radiation. Because the dose-response functions were not parallel, the RBE was not constant but rather increased with dose or, equivalently, with the probability of myelopathy. This required the development of a novel method of determining the RBE versus level of response. The RBE is presented as a function of probability of myelopathy from 0.1 to 99%. At a 50% incidence of myelopathy, the RBE (±1 SE) was 5.22 ± 0.15. A difference in the histopathology of lesions induced by photon and neutron treatments was observed.