Subacute Neuropathological Effects of Microplanar Beams of X-Rays from a Synchrotron Wiggler

Microplanar beam radiation therapy has been proposed to treat brain tumors by using a series of rapid exposures to an array of parallel x-ray beams, each beam having uniform microscopic thickness and macroscopic breadth (i.e., microplanar). Thirty-six rats were exposed head-on either to an upright 4...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1995-09, Vol.92 (19), p.8783-8787
Main Authors: Slatkin, D. N., Spanne, P., Dilmanian, F. A., J.-O. Gebbers, Laissue, J. A.
Format: Article
Language:English
Subjects:
Animals
Astrocytes - pathology
Brain
Brain - pathology
Brain - radiation effects
Collimation
Cranial Irradiation - adverse effects
Dose-Response Relationship, Radiation
Female
Irradiation
Light beams
Male
Medical research
Necrosis
Neurons - pathology
Photons
Radiation
Radiation dosage
Radiotherapy
Rats
Rats, Inbred F344
Rats, Sprague-Dawley
Rodents
Stripes
Synchrotrons
Tumors
X-Ray Therapy - adverse effects
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Summary:Microplanar beam radiation therapy has been proposed to treat brain tumors by using a series of rapid exposures to an array of parallel x-ray beams, each beam having uniform microscopic thickness and macroscopic breadth (i.e., microplanar). Thirty-six rats were exposed head-on either to an upright 4-mm-high, 20- or 37-μ m-wide beam or to a horizontal 7-mm-wide, 42-μ m-high beam of mostly 32- to 126-keV, minimally divergent x-rays from the X17 wiggler at the National Synchrotron Light Source at Brookhaven National Laboratory. Parallel slices of the head, separated at either 75 or 200 μ m on center, were exposed sequentially at 310-650 grays (Gy) per second until each skin-entrance absorbed dose reached 312, 625, 1250, 2500, 5000, or 10,000 Gy. The rats were euthanized 2 weeks or 1 month later. Two rats with 10,000-Gy-entrance slices developed brain tissue necrosis. All the other 10,000- and 5000-Gy-entrance slices and some of the 2500- and 1250-Gy-entrance slices showed loss of neuronal and astrocytic nuclei and their perikarya. No other kind of brain damage was evident histologically in any rat with entrance absorbed doses ≤5000 Gy. Brain tissues in and between all the 312- and 625-Gy-entrance slices appeared normal. This unusual resistance to necrosis is central to the rationale of microplanar beam radiation therapy for brain tumors.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.92.19.8783