Integrative Risk Models Toolkit
The following software is available for download by authorized users. To request the software, please contact the JSC Technology Transfer and Commercialization Office (TTO) at email@example.com.
The space radiation environment, particularly solar particle events (SPEs), poses the risk of acute radiation sickness (ARS) to humans; and organ doses from SPE exposure may reach critical levels during EVAs or within lightly shielded spacecraft. NASA has developed an organ dose projection model using the BRYNTRN with SUMDOSE computer codes, and a probabilistic model of Acute Radiation Risk (ARR). The risk projection models of organ doses and ARR take the output from BRYNTRN as an input to their calculations. With a graphical user interface (GUI) to handle input and output for BRYNTRN, the response models can be connected easily and correctly to BRYNTRN in a user-friendly way. A GUI for the Acute Radiation Risk and BRYNTRN Organ Dose (ARRBOD) v1.0 considered the prodromal syndrome and included several historical SPE spectra. ARRBOD v2.0 assesses the resultant early radiation risks from the blood forming organs (BFO) dose by using four biomathematical ARS models of lymphocytes depression, granulocytes modulation, fatigue and weakness syndrome, and upper gastrointestinal distress. The ARRBOD GUI is intended for mission planners, radiation shield designers, space operations in the mission operations directorate (MOD), and space biophysics researchers.
The GCR Event-based Risk Model (GERM) code is a stochastic model of space radiation transport being developed for new risk assessment approaches. The GERM code was built on the QMSFRG (quantum multiple scattering fragmentation) model and atomic interaction models used in HZETRN (high-charge and high-energy transport). Descriptions of particle track include the radial dose distribution and frequency of energy deposition in DNA volumes. Dose response models for cell survival and mutation, and Harderian gland tumors in mice described for mono-energetic or mixed particle fields behind shielding. The GERMcode is in excellent agreement with the NASA Space Radiation Laboratory (NSRL) and other laboratory physics measurements of fragmentation cross sections, particle fluence distributions, and the Bragg depth-dose curve. The GERMcode provides scientists participating in NSRL experiments: data interpretation of their experiments; the ability to model the beam line, shielding of samples and sample holders; and estimates of basic physical and biological outputs of experiments. The GERMcode will be the main tool to develop new time dependentstochastic descriptions of biological responses of interest for space radiation protection and Hadron therapy.
The NASA Radiation Track Image v3.0 (NasaRTI v3.0) has a compendium of codes and functions to model the effects of the high-charge high-energy (HZE) ion components of the galactic cosmic rays, which present unique challenges to biological systems in comparison to terrestrial forms of radiations. The GUI operates a deoxyribonucleic acid (DNA) breakage model to visualize and analyze the impact of chromatin domains and DNA loops on clustering of DNA damage from X-rays, protons, and HZE ions. The model of DNA breakage includes a stochastic process of DNA double-strand break (DSB) formation and is based on the averaged radiation track profile and a polymer model of DNA packed in the cell nucleus. Additionally, the NasaRTI provides a function to analyze patterns of DNA damage foci, especially from high-LET particles, which have characteristic streak-like patterns. To improve comparisons with the manual count of foci, the package includes a segmentation algorithm, for counting objects (including simple and co-localized DNA damage foci) in experimental images. In the NasaRTI v3.0, we include a radiated tissue model to provide an analysis tool of radiobiological data on tissue level.
RITRACKS is a Monte-Carlo code for the simulation of heavy ion and d-ray tracks in biomolecules using accurate ionization and excitation cross sections for liquid water. RITRACKS provides detailed information on energy deposition and production of radiolytic oxidative species, that damage cellular components, in targets and voxels of different sizes at the micro or nano scale. RITRACKS provides a useful evaluation tool over the charge and energy range of interest for space radiation protection and Hadron therapy studies. It also provides the visualization capability of the microscopic 3-D tracks. RITRACKS will provide stochastic track descriptions of the whole genome by improving the radiation chemistry algorithms of other species and including various biological targets.
To guide medical personnel in making clinical decisions for effective medical management and treatment of exposed individuals in a radiology/nuclear disaster event, biological markers that reflect radiation induced changes may be employed to assess the extent of radiation injury. Among these markers, the most widely used are peripheral blood cell counts. The HemoDose tools are built upon solid physiological and pathophysiological understanding of mammalian hematopoietic systems, and rigorous coarse-grained bio-mathematical modeling and validation. Using single or serial counts of granulocyte, lymphocyte, leukocyte, or platelet after exposure, these tools can estimate absorbed doses of adult victims very rapidly and accurately. Patient data in historical accidents are utilized as examples to demonstrate the capabilities of these tools as a rapid point-of-care diagnostic or centralized high-throughput assay system in a large scale radiological disaster scenario. Unlike previous dose prediction algorithms, the HemoDose tools establish robust correlations between the absorbed doses and victim's various types of blood cell counts not only in the early time window (1 or 2 days), but also in very late phase (up to 4 weeks) after exposure.
HZETRN2015 is the latest update of the HZETRN deterministic space radiation transport code. HZETRN2015 contains new algorithms and options for calculating three dimensional transport in user-defined combinatorial or ray-trace geometry. More computationally efficient bi-directional transport algorithms, similar to those found in HZETRN2010, may also be used to perform transport through multilayer slabs, or users can opt to create an interpolation database for various thicknesses within one to three user-defined material layers using a straight-ahead transport algorithm, similar to HZETRN2005. Transport calculations may be executed for Galactic Cosmic Ray (GCR), Solar Particle Event (SPE), Low Earth Orbit (LEO), and user-defined environment boundary conditions. Neutrons, protons, and light ions are transported for SPE and LEO boundary conditions, while for GCR boundary conditions, heavy ions, pions, muons, electrons, positrons, and photons are also transported.
Online Tools and Models
The following online tools and models are available for authorized users. To request a username and password to access these tools, please contact the JSC Technology Transfer and Commercialization Office (TTO) at firstname.lastname@example.org.
Solar Particle Events (SPEs) occur quite often over the approximately 11-year solar cycle, but are highly episodic and almost unpredictable. They represent a major threat to crews of space exploration missions. During such events, the flux of protons with energy greater than 10 MeV may increase over background by 4 to 5 orders of magnitude for a period of several hours to a few days. The hazards of exposure to these large doses have to be evaluated in the context of the high competing risks of vehicle or life support system failures. In addition to the risk of cancer and other late effects such as the neuronal and heart disease risks and cataracts, the appraisal of Acute Radiation Sickness (ARS) assumes prime importance because it can impair the performance capabilities of crew members and thereby threaten mission success. In this ARRBOD web server, the Baryon transport (BRYNTRN) code is used to transport primary SPE protons and their nuclear reaction products through various media for the estimation of organ doses. The radiation shielding by body tissue at specific organ sites was accounted for by using ray tracing in the human phantom models of the Computerized Anatomical Male (CAM) and the Computerized Anatomical Female (CAF), and the resultant early radiation risks were assessed for the blood forming organs (BFO) dose by using the four biomathematical ARS models, which include lymphocytes depression, granulocytes modulation, fatigue and weakness syndrome, and upper gastrointestinal distress. The flow charts of BRYNTRN Organ Dose calculation and Acute Radiation Risk calculation provide an overview of the functions of this web server.
Exposure to solar particle events (SPE) and galactic cosmic rays (GCR) poses cancer risks to astronauts. The NASA Johnson Space Center Space Radiation Program Element (JSC-SRPE) has developed cancer risk projection code and has evaluated the level of uncertainty that exists for each of the factors (parameters) that are used in the model. The model originated from recommendations of the National Council on Radiation Protection and Measurements (NCRP, 1997; 2000) with revisions from the latest analysis of human radio-epidemiology data. NASA-defined radiation quality factors are formulated with probability distribution functions (PDFs) to represent uncertainties in leukemia and solid cancer risk estimates. The model was reviewed by the National Research Council (NRC) in 2012. Monte-Carlo propagation of uncertainties from different sources is described with PDFs. Models of the space environment and the BRYNTRN and the HZETRN are used to determine organ exposures behind spacecraft shielding. The purpose of the NASA Space Cancer Risk (NSCR) web server is to provide seamless integration of input and output manipulations, which are required for operation of the sub-modules--BRYNTRN, SUMSHIELD, and the Cancer probabilistic response models. The main applications envisioned are International Space Station (ISS) missions, and planning for future exploration missions to the moon, near earth objects (NEO), or Mars. In addition, cancer risk estimates for medical diagnostic and aviation radiation exposures are evaluated using similar methods.
This tool is discussed in detail in the following TP-2013-217375.
The On-Line Tool for the Assessment of Radiation in Space (OLTARIS,) is a web-based set of tools and models that allows engineers and scientists to assess the effects of space radiation on spacecraft, habitats, rovers, and spacesuits. The site is intended to be a design tool for those studying the effects of space radiation for current and future missions as well as a research tool for those developing advanced material and shielding concepts. The tools and models are built around the HZETRN2010 radiation transport code and are primarily focused on human and electronic-related responses.
The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a NASA physics-based prototype operational model for predicting aircraft radiation exposure from galactic and solar cosmic rays. NAIRAS predictions are currently streaming live from the project's public website. The NAIRAS model provides data-driven, global, real-time predictions of atmospheric ionizing radiation exposure rates on a geographic 1x1 degree latitude and longitude grid from the surface of the Earth to 100 km with a vertical resolution of 1 km. The real-time, global predictions are updated every hour. Physics-based models are utilized within NAIRAS to transport cosmic rays through three distinct material media: the heliosphere, Earth's magnetosphere, and the neutral atmosphere. The physics-based models are input-driven by real-time measurement data. An initial validation of the NAIRAS model has been conducted by comparing with reference aircraft radiation measurement data and with recent aircraft measurements provided by the German Aerospace Corporation. Further validation studies will be performed via the NASA Radiation Dosimetry Experiment (RaD-X) balloon flight mission, which is scheduled to launch in 2015. The Automated Radiation Measurements for Aviation Safety (ARMAS) project, led by Space Environment Technologies, is developing the technology to improve the NAIRAS model with real-time aircraft radiation measurements using data assimilation methods.
After the events of September 11, 2001 and recent events at the Fukushima reactors in Japan, there is an increasing concern of the occurrence of nuclear and radiological terrorism or accidents that may result in large casualty in densely populated areas. To guide medical personnel in their clinical decisions for effective medical management and treatment of the exposed individuals, biological markers are usually applied to examine the radiation induced changes at different biological levels. Among these the peripheral blood cell counts are widely used to assess the extent of radiation induced injury. This is due to the fact that hematopoietic system is the most vulnerable part of the human body to radiation damage. Particularly, the lymphocyte, granulocyte, and platelet cells are the most radiosensitive of the blood elements, and monitoring their changes after exposure is regarded as the most practical and best laboratory test to estimate radiation dose. The HemoDose web tools are built upon solid physiological and pathophysiological understanding of mammalian hematopoietic systems, and rigorous coarse-grained bio-mathematical modeling and validation. Using single or serial granulocyte, lymphocyte, leukocyte, or platelet counts after exposure, these tools can estimate absorbed doses of adult victims very rapidly and accurately. Some patient data in historical accidents are utilized as examples to demonstrate the capabilities of these tools as a rapid point-of-care diagnostic or centralized high-throughput assay system in a large scale radiological disaster scenario. Unlike previous dose prediction algorithms, the HemoDose web tools establish robust correlations between the absorbed doses and victim's various types of blood cell counts not only in the early time window (1 or 2 days), but also in very late phase (up to 4 weeks) after exposure.
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