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Chromosome Aberration in Human Blood Lymphocytes Exposed to Energetic ProtonsDuring space flight, astronauts are exposed to a space radiation consisting of high-energy protons, high charge and energy (HZE) nuclei, as well as secondary particles that are generated when the primary particles penetrate the spacecraft shielding. Secondary particles have a higher LET value than primary protons and therefore expected to have a higher relative biological effectiveness (RBE). To investigate this theory, we exposed human peripheral blood lymphocytes to protons with energies of 250 MeV, 800MeV, 2 GeV, or 2.5 GeV. LET values for these protons ranged from 0.4 to 0.2 keV/micrometer. and doses ranged from 0.2 to 3 Gy. Over this energy the probability of nuclear reaction leading to secondary radiation, and the multiplicity of reaction produces such as neutrons and mesons increases substantially. The effect of aluminum and polyethylene shielding was also assessed using the 2 GeV and 2.5GeV proton beams. After exposure lymphocytes were stimulated to divide and chromosomes were collected from cells in the first G2 and metaphase cell cycle after exposure using a chemical induced premature chromosome condensation (PCC) technique. Dose response data for chromosome damage was analyzed using the fluorescence in situ hybridization (FISH) chromosome painting technique. Selected samples were also analyzed with multicolor FISH (mFISH) and multicolor banding FISH (mBAND) techniques. Data indicates that the dose response for simple-type exchanges is similar for proton and gamma exposure, whereas protons induce higher yields of complex exchanges that are LET dependent. RBE values will be presented for each proton energy, and the effects of shielding and possible cytogenetic signatures of proton exposure will be discussed.
Document ID
Acquisition Source
Johnson Space Center
Document Type
Hada, M.
(NASA Johnson Space Center Houston, TX, United States)
George, Kerry A.
(NASA Johnson Space Center Houston, TX, United States)
Cucinotta, F. A.
(NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2008
Subject Category
Aerospace Medicine
Meeting Information
Meeting: 37th COSPAR Scientific Assembly
Location: Montreal
Country: Canada
Start Date: July 13, 2008
End Date: July 20, 2008
Sponsors: Committee on Space Research
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