Evolution of the Health Canada astronaut biodosimetry program with a view toward international harmonization

Assessment of Radiosensitivity and Biomonitoring of Exposure to Space Radiation

“…The use of cytogenetics assays to assess radiation effects in astronauts during spaceflight, have been applied since the late 1990's (Durante et al 2003;Fedorenko et al 2001;George et al 2004George et al , 2001Obe et al 1997;Testard et al 1996;Yang et al 1997). In general, these studies and more recent ones (Beaton-Green et al 2015;Cucinotta et al 2008;George et al 2010George et al , 2013 have shown that the number of chromosomal aberrations significantly increased during the mission, although there were large interindividual differences, which could not be attributed to the measured dose. This variability could be a consequence of differences in radiation sensitivity, but the experimental uncertainties were so high that the result could also be explained by statistical fluctuations (Durante 2005) because the doses to which the astronauts were exposed were close to the sensitivity thresholds of the assays (Cologne et al 1998).…”

“…As previously mentioned, classical cytogenetic measurements such as dicentrics and chromosomal translocations have been mostly used to detect chromosomal aberrations in peripheral blood lymphocytes of astronauts returning from longterm space missions (Beaton-Green et al 2015;Cucinotta et al 2008;Durante et al 2003;Fedorenko et al 2001;George et al 2001George et al , 2004George et al , 2010George et al , 2013Obe et al 1997;Testard et al 1996;Yang et al 1997). In the next paragraphs, we will review some emerging technologies which might be useful for high-throughput screening of interindividual differences in radiosensitivity.…”

Long-Term Persistence of Increased Number of γH2AX+ Peripheral Blood Lymphocytes in Monkeys Exposed to Negative Factors of Space Flights: Ionizing Radiation and Simulated Hypogravity

“…A similar phenomenon of prolonged persistence of an increased number of peripheral blood lymphocytes with DNA damage is observed in cosmonauts and astronauts. It has been shown that these damaged blood lymphocytes can be found during several months after the flight [3,5]. It should be noted that this phenomenon can be explained not only by long life-span of lymphocytes with non-critical damages, but also by the deceleration of DNA repair processes under conditions of microgravity [9].…”

Monte Carlo Modelling of an Orthovoltage X-ray System Using Multiple Applications in EGSnrc

“…Alternatively, a stable chromosome aberration could be used for an assay, providing a less strict time window in which a sample can be analyzed. One such example is another common biodosimetry assay called translocation analysis using Fluorescent In Situ Hybridization (FISH) assay [5], [8], [15]- [18]. This technique relies on quantifying chromosome translocations, which involve a broken end of a chromosome attaching itself to another chromosome (or sometimes an exchange of broken ends between two chromosomes), resulting in chromosomes that can appear morphologically correct, having only one centromere.…”

“…Reading Output with Filter (1, 2, or 3) Reading Output with no filter (18) Figure 32 shows the percentage difference of the electrometer reading ratios taken in the laboratory and the dose output ratios from the BEAMnrc or SpekPy models. The points are arranged in order of level of filtration or beam hardness, going from lowest to highest.…”