The Effects of Fractionated Doses of Fast Neutrons or Photons on the Canine Cervical Spinal Cord

The cervical spinal cords of 36 young adult male beagles were irradiated with fast neutrons with a mean energy of 15 MeV in four fractions/week/5 weeks to total doses of 1167, 1750, 2625, or 3938 rad. Nineteen beagles received 3500, 5250, or 7875 rad of photons in like manner. Sensory evoked respons...

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Bibliographic Details
Published in:Radiation research 1981-10, Vol.88 (1), p.165-179
Main Authors: Zook, Bernard C., Bradley, Eileen W., Casarett, George W., Fisher, Mary Phyllis, Rogers, Charles C.
Format: Article
Language:English
Subjects:
Animals
Cerebrospinal fluid
Cerebrospinal Fluid Proteins - analysis
Dogs
Dose-Response Relationship, Radiation
Elementary Particles
Erythrocyte Count
Evoked Potentials
Fast Neutrons
Hemorrhage
Irradiation
Male
Neoplasms, Radiation-Induced
Neutrons
Paralysis - etiology
Photons
Radiation dosage
Radiotherapy
Relative Biological Effectiveness
Spinal cord
Spinal Cord - radiation effects
Spinal Cord Neoplasms - etiology
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Summary:The cervical spinal cords of 36 young adult male beagles were irradiated with fast neutrons with a mean energy of 15 MeV in four fractions/week/5 weeks to total doses of 1167, 1750, 2625, or 3938 rad. Nineteen beagles received 3500, 5250, or 7875 rad of photons in like manner. Sensory evoked responses recorded before and periodically after irradiations remained stable on 22 test and 6 control dogs. The cerebrospinal fluid contained excess protein and erythrocytes often before and always after the onset of neurological symptoms. All dogs in the 3938-rad neutron, 6/9 dogs in the 2625-rad neutron, and 4/6 dogs in the 7875-rad photon groups developed cervical muscular spasms, incoordination, and progressive paralysis and were euthanatized. The relative biological effectiveness of fast neutrons as measured by the onset of neurological signs is approximately 3 (7875 photons/2625 neutrons) and is less than 4.5 (7875 photons/1750 neutrons). Gross pathological findings included hemorrhages, softening, and poliomyelomalacia, especially of the dorsal horns. Two dogs developed neoplasms in the irradiated field 1065 and 1470 days following neutron irradiation.
ISSN:0033-7587
1938-5404
DOI:10.2307/3575761