Interlaced X-Ray Microplanar Beams: A Radiosurgery Approach with Clinical Potential

Interlaced X-Ray Microplanar Beams: A Radiosurgery Approach with Clinical Potential

Studies have shown that x-rays delivered as arrays of parallel microplanar beams (microbeams), 25- to 90-μm thick and spaced 100-300 μm on-center, respectively, spare normal tissues including the central nervous system (CNS) and preferentially damage tumors. However, such thin microbeams can only be...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS Vol. 103; no. 25; pp. 9709 - 9714
Main Authors: Dilmanian, F. Avraham, Zhong, Zhong, Bacarian, Tigran, Benveniste, Helene, Romanelli, Pantaleo, Wang, Ruiliang, Welwart, Jeremy, Yuasa, Tetsuya, Rosen, Eliot M., Anschel, David J.
Format: Journal Article
Language:English
Published: United States National Academy of Sciences 20-06-2006
National Acad Sciences
Subjects:
Animals
Biological Sciences
BRAIN
Brain - surgery
Brain damage
CENTRAL NERVOUS SYSTEM
Dosage
GEOMETRY
IMPLEMENTATION
Irradiation
Laser beams
Magnetic Resonance Imaging
national synchrotron light source
NEOPLASMS
Nervous system
PARTICLE ACCELERATORS
Radiation damage
Radiation therapy
Radiosurgery - methods
RADIOTHERAPY
Rats
Rodents
Side effects
SPINAL CORD
Spinal Cord - surgery
Studies
SURGERY
SYNCHROTRONS
TARGETS
TOLERANCE
Tumors
X-Rays
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Summary:Studies have shown that x-rays delivered as arrays of parallel microplanar beams (microbeams), 25- to 90-μm thick and spaced 100-300 μm on-center, respectively, spare normal tissues including the central nervous system (CNS) and preferentially damage tumors. However, such thin microbeams can only be produced by synchrotron sources and have other practical limitations to clinical implementation. To approach this problem, we first studied CNS tolerance to much thicker beams. Three of four rats whose spinal cords were exposed transaxially to four 400-Gy, 0.68-mm microbeams, spaced 4 mm, and all four rats irradiated to their brains with large, 170-Gy arrays of such beams spaced 1.36 mm, all observed for 7 months, showed no paralysis or behavioral changes. We then used an interlacing geometry in which two such arrays at a 90° angle produced the equivalent of a contiguous beam in the target volume only. By using this approach, we produced 90-, 120-, and 150-Gy 3.4 x 3.4 x 3.4 mm³ exposures in the rat brain. MRIs performed 6 months later revealed focal damage within the target volume at the 120- and 150-Gy doses but no apparent damage elsewhere at 120 Gy. Monte Carlo calculations indicated a 30-μm dose falloff (80-20%) at the edge of the target, which is much less than the 2- to 5-mm value for conventional radiotherapy and radiosurgery. These findings strongly suggest potential application of interlaced microbeams to treat tumors or to ablate nontumorous abnormalities with minimal damage to surrounding normal tissue.
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content type line 23
BNL-78966-2007-JA
DE-AC02-98CH10886
Doe - Office Of Science
dPresent address: University of California, Irvine, CA 92697
iPermanent address: Faculty of Engineering, University of Yamagata, Yamagata, Japan.
Author contributions: F.A.D., Z.Z., H.B., and D.J.A. designed research; F.A.D., Z.Z., T.B., H.B., R.W., J.W., T.Y., and D.J.A. performed research; F.A.D., H.B., P.R., R.W., J.W., E.M.R., and D.J.A. analyzed data; and F.A.D., Z.Z., H.B., P.R., R.W., E.M.R., and D.J.A. wrote the paper.
Communicated by Richard B. Setlow, Brookhaven National Laboratory, Upton, NY, May 2, 2006
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0603567103