Radiation risk predictions for Space Station Freedom orbits

Risk assessment calculations are presented for the preliminary proposed solar minimum and solar maximum orbits for Space Station Freedom (SSF). Integral linear energy transfer (LET) fluence spectra are calculated for the trapped proton and GCR environments. Organ dose calculations are discussed using the computerized anatomical man model. The cellular track model of Katz is applied to calculate cell survival, transformation, and mutation rates for various aluminum shields. Comparisons between relative biological effectiveness (RBE) and quality factor (QF) values for SSF orbits are made

How Space Radiation Risk from Galactic Cosmic Rays at the International Space Station Relates to Nuclear Cross Sections

Space radiation risk to astronauts is a major obstacle for long term human space explorations. Space radiation transport codes have thus been developed to evaluate radiation effects at the International Space Station (ISS) and in missions to the Moon or Mars. We study how nuclear fragmentation processes in such radiation transport affect predictions on the radiation risk from galactic cosmic rays. Taking into account effects of the geomagnetic field on the cosmic ray spectra, we investigate the effects of fragmentation cross sections at different energies on the radiation risk (represented by dose-equivalent) from galactic cosmic rays behind typical spacecraft materials. These results tell us how the radiation risk at the ISS is related to nuclear cross sections at different energies, and consequently how to most efficiently reduce the physical uncertainty in our predictions on the radiation risk at the ISS

Radiation Risk Projections for Space Travel

Space travelers are exposed to solar and galactic cosmic rays comprised of protons and heavy ions moving with velocities close to the speed of light. Cosmic ray heavy ions are known to produce more severe types of biomolecular damage in comparison to terrestrial forms of radiation, however the relationship between such damage and disease has not been fully elucidated. On Earth, we are protected from cosmic rays by atmospheric and magnetic shielding, and only the remnants of cosmic rays in the form of ground level muons and other secondary radiations are present. Because human epidemiology data is lacking for cosmic rays, risk projection must rely on theoretical understanding and data from experimental models exposed to space radiation using charged particle accelerators to simulate space radiation. Although the risks of cancer and other late effects from cosmic rays are currently believed to present a severe challenge to space travel, this challenge is centered on our lack of confidence in risk projections methodologies. We review biophysics and radiobiology data on the effects of the cosmic ray heavy ions, and the current methods used to project radiation risks . Cancer risk projections are described as a product of many biological and physical factors, each of which has a differential range of uncertainty due to lack of data and knowledge. Risk projections for space travel are described using Monte-Carlo sampling from subjective error di stributions that represent the lack of knowledge in each factor that contributes to the projection model in order to quantify the overall uncertainty in risk projections. This analysis is applied to space mi ssion scenarios including lunar colony, deep space outpost, and a Mars mission. Results suggest that the number of days in space where cancer mortality risks can be assured at a 95% confidence level to be below the maximum acceptable risk for radi ation workers on Earth or the International Space Station is only on the order of 100-200 days. Approaches to reduce these unceI1ainties and mitigate risks are described

Biological Bases of Space Radiation Risk

In this session, Session JP4, the discussion focuses on the following topics: Hematopoiesis Dynamics in Irradiated Mammals, Mathematical Modeling; Estimating Health Risks in Space from Galactic Cosmic Rays; Failure of Heavy Ions to Affect Physiological Integrity of the Corneal Endothelial Monolayer; Application of an Unbiased Two-Gel CDNA Library Screening Method to Expression Monitoring of Genes in Irradiated Versus Control Cells; Detection of Radiation-Induced DNA Strand Breaks in Mammalian Cells By Enzymatic Post-Labeling; Evaluation of Bleomycin-Induced Chromosome Aberrations Under Microgravity Conditions in Human Lymphocytes, Using "Fish" Techniques; Technical Description of the Space Exposure Biology Assembly Seba on ISS; and Cytogenetic Research in Biological Dosimetry

DNA Damage Signals and Space Radiation Risk

Space radiation is comprised of high-energy and charge (HZE) nuclei and protons. The initial DNA damage from HZE nuclei is qualitatively different from X-rays or gamma rays due to the clustering of damage sites which increases their complexity. Clustering of DNA damage occurs on several scales. First there is clustering of single strand breaks (SSB), double strand breaks (DSB), and base damage within a few to several hundred base pairs (bp). A second form of damage clustering occurs on the scale of a few kbp where several DSB?s may be induced by single HZE nuclei. These forms of damage clusters do not occur at low to moderate doses of X-rays or gamma rays thus presenting new challenges to DNA repair systems. We review current knowledge of differences that occur in DNA repair pathways for different types of radiation and possible relationships to mutations, chromosomal aberrations and cancer risks

Impact of Allura Clarity technology on radiation dose exposure during left atrial appendage closure

Background: To evaluate the impact of the Clarity IQ technology on reducing radiation risk in patients undergoing cardiac interventional radiology (IR) procedures. Material/Methods: Phantom studies were performed with two angiographic systems, FD10 Allura Xper and FD10 Allura Clarity. In the study, we performed left atrial appendage closure. Dosimetric measurements were performed with thermoluminescent dosimeters (TLD) placed inside a CIRS anthropomorphic phantom. Radiation risk was estimated based on the TLD readings and expressed as the dose absorbed by particular organs. The Mann-Whitney U test was carried out to test for significance of differences in the absorbed radiation doses between the techniques. Results: During left atrial appendage closure, the estimated dose absorbed by particular organs was lower in the case of the FD10 Allura Clarity system in comparison to the Allura Xper. In this procedure, dose reduction for particular organs ranged between 49-86%. Conclusions: Application of the FD10 Allura Clarity system resulted in a significant dose reduction, thereby leading to a significant decrease in radiation risk for patients undergoing IR procedures

Awareness of Theatre Team to Radiation Risk From C-Arm During Surgical Procedures: A Case Study of University of Calabar Teaching Hospital in Nigeria

Purpose: This study aims to assess the awareness of the theatre team to radiation risk from C-arm as well as their adherence to radiation protection or safety measures in the study Centre. Methods: A non-experimental descriptive design was adopted for this study and a well-structured 27 item questionnaire was distributed to 52 members of the surgical theatre: Surgeons, Anesthesiologists, Theatre nurses and Radiographers in the selected hospital. Of this sample, 49 respondents returned their questionnaires. Results. Results from this study reveal a high level (83.67%) of knowledge of radiation risk from C-arm. A greater percentage of the respondents have an average level of knowledge of radiation protection or safety measures: Surgeons (58.8%), Anesthesiologists (50%), and Theatre Nurses (33.3%). Of this percentage on awareness, only 41.1% of Surgeons, 30% of Anesthesiologists, 16.6% of theatre Nurses adhere to these radiation protection/safety measures. This study further reveals a low level of awareness and use of radiation monitoring devices: Surgeons (29.4%), Anesthesiologists (10%), and Theatre Nurses (8.3%). Also, the study shows that the surgical team spends long periods during surgical procedures: 4 hours (24.48%), 6 hours (20.4%), 12 hours (6.12%), thus increasing their susceptibility to radiation effects. The study further affirms that a lesser percentage of the respondents (44.89%) knew the safest positioning of the radiation-emitting tube, meaning that a greater percentage of the respondents don’t know the safest position to take during beam-on periods. Conclusion: This study shows a high level of knowledge of radiation risk, an average level of awareness to radiation protection/safety measures and a poor level adherence of these measures by the theater team

The relationship between geographical region and perceptions of radiation risk after the Fukushima accident: The mediational role of knowledge

Since the Fukushima accident, radiation risk perception has been of public concern. Factors related to regional differences in radiation risk perception and the role that knowledge of radiation effects plays are still not clearly understood. Here, we first assessed the validity of the Lindell radiation risk perception scale by comparing it with the mortality rate of traffic accidents. We then investigated the relationship between the perceptions and both the geographical regions and the knowledge of genetic effects and, further, verified the mediating role of knowledge in the perception. The sample comprised 832 participants who responded to an online questionnaire in August 2018, from Tokyo and Fukushima. There was a significant association between the Lindell scale and the perceived magnitude of genetic risk relative to traffic accident mortality. Knowledge of genetic effects after the atomic bombs was associated with perceptions of lower genetic risks. The relationship between geographical region and risk perception was mediated by knowledge. However, approximately 40% of those who had knowledge still perceived a high risk, indicating that perception is not governed by knowledge alone. In addition to efforts to share knowledge, it is important to interactively communicate regarding risk to alleviate the anxiety felt by individuals

Local DRLs and automated risk estimation in paediatric interventional cardiology

Introduction : Cardiac catheterization procedures result in high radiation doses and often multiple procedures are necessary for congenital heart disease patients. However, diagnostic reference levels (DRL) remain scarce. Our first goal was finding the optimal DRL parameter and determining appropriate DRLs. The second goal was to calculate organ doses (OD), effective doses (ED) and lifetime attributable risks (LAR) per procedure and to provide conversion factors based on dose area product (DAP). Materials and methods : DRLs are calculated for each procedure type, as the 75th percentile of the cumulative value per procedure from the corresponding parameter. All irradiation events in the DICOM Structured Reports were automatically processed and simulated using PCXMC, resulting in OD, ED and LAR. Using a Kruskal Wallis H test and subsequent pairwise comparisons, differences in median values of the DRL parameter between procedure types were assessed. Results : Linear regression showed a strong correlation and narrow confidence interval between DAP and product of body weight and fluoroscopy time (BWxFT), even when all procedures (diagnostic and interventional) are combined. Only 15% of the pairwise comparisons were statistically significant for DAP normalized to BWxFT (DAP(BWxFT)). The latter pairs contained less frequent procedure types with significant outliers. For DAP normalized to BW (DAP(BW)), 38% of the pairwise comparisons showed statistically significant differences. Conversion factors from DAP(BW) to OD and ED were reported for various weight groups, due to the higher correlation between DAP(BW) and both OD and ED than between DAP and both OD and ED. Conclusions : The P75 of DAP(BWxFT) for all procedures combined serves as an appropriate DRL value. This facilitates local DRL determination in smaller paediatric centres, which often have insufficient data to produce appropriate DRLs for different procedure types. Conversion factors are more reliable starting from DAP(BW) instead of DAP and should be used according to the appropriate BW group