1. Review on Ionizing Radiation and Radiation
Monitoring in Low Earth Orbit
“My God, space is radioactive!
- Ernie Ray (1958)
Sample Presentation – Not a finalized document
Modified for Online Distribution
2. Overview
• Ionizing Radiation
• Dose Terminology
• Earth, High Altitude and Space Radiation Sources
• Biological Effects of Radiation
• Regulations and Standards
2
5. • Defined as particles that have sufficient energy to remove an electron
from an atom or molecule (becoming electrically charged) while also
capable of damaging DNA
• Various types of radiation affects the body in different ways
• ALL radiation exposure (no matter how small) has associated health risks
• Linear No-Threshold Model
• X-rays, gamma-rays, neutrons, protons, electrons and heavy ion particles
are examples of ionizing radiation
5
Ionizing Radiation
7. Ionizing Radiation (Cont.)
• Can cause severe cell damage (DNA), leading to various forms of cancer
• Radioactive decay of particles may take the form of:
• Beta (β) particles
• β+ = positron
• β- = electron
• Alpha (α) particles – Charged helium nuclei
• Neutrons
• Radioactive sources may include
• Radon-222: naturally occurring α emitter
• Potassium-40: naturally occurring β emitter
• Cobalt-60: used in medical equipment sterilization – emits 2 high energy γ via β decay
• Neutrons: Secondary particle from charged ions interacting with shielding
7
Gamma-ray (γ) emission
May lead to
X-ray emission
8. • Absorbed Dose (D) is a measure of the energy absorbed per unit mass of
material
• Units of Gray (Gy) or rad
• 1 Gy = 100 rad
• All tissue within a radiation beam (i.e. X-ray) will not absorb the same
amount of radiation dose
8
Radiation:
Dose Terminology – Absorbed Dose
9. • Equivalent Dose (H) relates Radiation Biological Effectiveness (RBE) of
radiation exposure with a Quality Factor (Q)
• Units of Sieverts (Sv) or rem
• 1 Sv = 100 rem
• RBE compares effectiveness of one radiation against gamma radiation
• Value of Q for each radiation type assigned by ICRP 26 and 60
• H = Q * D
9
Radiation:
Dose Terminology – Equivalent Dose
10. Type of Radiation Quality
Factor
(Q)
Absorbed Dose equal to
1 Equivalent Dose unit
(D = H ÷ Q)*
X-ray, Gamma ray, Beta 1 1
Alpha, Multiple-charge Particles,
Fission Fragments, Heavy Particles
20 0.05
Neutrons 10 0.1
High-energy protons 10 0.1
* Absorbed dosein rad equal to 1 rem or in Gy equal to 1 Sv
10
Radiation:
Quality Factor
13. Radiation:
Earth Radiation Sources
• Radon gas emissions produce the largest hazard to radiation exposure
on the ground
• Earth’s atmosphere shields against most cosmic radiation
13 World Nuclear Organization (WNO)
14. Radiation:
High Altitude Exposure
• Jet altitudes ~6.1 km to 18 km
• Exposure from radiation originating from space
• Galactic Cosmic Rays (GCR)
• Solar Particle Events (SPE)
• Annual exposure to flight crews is ~1 to 6 mSv
• GCR and SPE particles interact with atoms in Earth’s atmosphere
creating numerous secondary particles
• Dose from GCR, SPE and secondary particles in correlation to high/low solar
activity
14
15. Radiation:
Neutron Count Rate and Sunspot Number
15
Neutron count rate and sunspotnumber plotted against date. Sunspotnumber per month (indication
of the heliocentric potential); monthly average of the hourly neutron count from the Climax,
Colorado ground-based neutron monitor (Lewis, B. J. et al 2001)
16. Radiation:
High Altitude Environment
17
Typical cursing altitude of jet aircraft
~6.1 – 18 km above the Earth’s surface
6.1 km
18 km
Cosmic Ray
Protons
Neutrons
Pions
Muons
Photons
Electrons + Positrons
• GCR (and SPE) particles interact
with molecules in the atmosphere
(nitrogen, oxygen, etc.) if they are
not shielded by Earth’s magnetic
field.
• Interaction causes a wide range of
secondary particles which contribute
to the dose in high altitudes (as well
as on the ground).
• Effect of GCRs generally much
greater than SPE
400 km
• SPEs much more
frequent during high
solar activity
• Occasionally, an SPE
can cause a significant
dose at high altitudes
Artwork courtesy of Windowsof the Universe
17. Data from National Oceanic and Atmospheric Administration (NOAA)
18
Radiation:
Space Exposure – Solar Cycle
• Period of solar cycle is
11 years
• Magnetic field polarity
reverses between each
cycle
18. Radiation:
Space Exposure – Solar Particle Events (SPE)
• Solar flares and Coronal Mass Ejections (CMEs)
• Statistically, most SPE which impact the Earth are not large events
• Consists mainly of p+, but also contains some ions of higher mass
• Unpredictable. Evaluate SPE as they unfold
• Capable of producing radiation levels lethal hours after an event occurs
19
20. • Radiation that originates from outside the solar system
• Supernova explosions from massive stars
• Solar Cycle dependent
• Highest during Solar Minimum
• Extremely penetrating and biologically damaging
21
Radiation:
Space Exposure – Galactic Cosmic Rays (GCR)
21. Advanced Composition Explorer (ACE) Website
22
Radiation:
Space Exposure – Cosmic Abundances
• Particles include highly
energetic p+ and heavy ion
(HZE) particles
• 90% protons
• 9% alpha (α) particles – 4He
• 1% HZE particles
22. • p+ and e- trapped in Earth magnetic field (Van Allen Radiation Belts)
• Inner Belt mostly protons > 10MeV. Reaches ~7700 km from Earth’s Surface
• Outer Belt mostly electrons < 10MeV. Reaches ~51 500 km from Earth’s Surface
• Exposure a function of altitude, inclination and solar cycle position
• Proton exposure highest at Solar Minimum
• e- penetrate EVA suit, but not spacecraft
23
Radiation:
Trapped Particles
23. SRAG
SRAG
24
Radiation:
Trapped Particles – South Atlantic Anomaly (SAA)
• Region of high radiation exposure
(determined from past missions whose
orbits intersected SAA)
• Result of the offset between Earth’s
geographical and magnetic axes
• Inner Van Allen Belt reaches a
minimum of 200 km above Atlantic
Ocean and South America
24. • Accounts for approximately 10 – 30% of the dose equivalent received by
astronauts onboard spacecraft in LEO
• Extremely penetrating and can cause cellular damage to internal organs
• Canadian-Russian experiments to characterize neutron field in LEO have
been performed since the late 1980’s
25
Space Radiation Environment:
Neutrons
25. 26
Space Radiation Environment:
Neutrons
• Originate from charged particles (SPE, GCR and trapped) interacting
with:
1. Spacecraft (spallation/evaporation neutrons): ~20% of total
neutron dose
2. Earth’s atmosphere (albedo neutrons): ~80% of total neutron dose
27. Inner Van Allen Belt
• p+ > 10 MeV, e- ~ 100 keV
• Altitude ~ 7 700 km
• p+ result of neutron decay
(beta decay)
Outer Van Allen Belt
• e- < 10 MeV
• Altitude ~51 500 km
• Trapped by Earth’s magnetosphere
ISS Orbit
Galactic Cosmic Rays (GCR)
• High-energy p+ (90 %)
• α particles (9%)
• Ionized heavier particles – He to U (1 %)
• Originate from outside Solar System
(Supernovae)
• Highest during Solar Minimum
• 100 MeV < Energy < 10 GeV
Solar Particle Events (SPE)
• High-energy p+, α particles, X-
rays
• Highest during Solar Maximum
• Solar Flares
• Coronal Mass Ejections (CME)
• 10 MeV < Energy < 100 MeV
ISS
Secondary Particles
• Protons, neutrons, X-rays, α-particles,
heavy ions (with sufficient energy)
South Atlantic Anomaly (SAA)
• Intersection of Earth’s Atmosphere with Inner belt
• Increased dose when ISS passes through region
• Attitude ~200 km
Rotational
Axis
Magnetic
Axis
29
Radiation:
Space Environment
11.4
29. • Types of radiation risk include:
• Deterministic (Cell death)
• Radiation sickness
• Nausea
• Skin reddening
• Stochastic (Cell Modification)
• Probability of occurrence in
population a function of dose
• Cancer (leukemia, lung,
thyroid)
• Genetic effects
Radiation:
Biological Effects
31
• Acute effects are not expected to result from exposure to the radiation
environments in space, with the exception of SPE
• Major concern about radiation in space is long term effects, such as cancer
or genetic effects
30. • Risk of acute effects during shuttle or ISS missions is considered to be
minimal
• Increase in cancer risk is the principal concern for astronaut exposure to
space radiation
• Delayed effects (e.g. cancer) can appear months (or years) after exposure. Even the
smallest dose increases the chance of developing this condition
32
Radiation:
Biological Effects (Cont.)
31. • Ionizing radiation causes atoms and molecules to become excited
(ionized). This can cause:
• Free radicals
• Breaking of original chemical bonds (and forming new bonds)
• Damage to molecules that regulate vital cell process (DNA, RNA, proteins)
• Heavy ion particles are more damaging to vital cells
33
Radiation:
Biological Effects (Cont.)
33. • Particles with a higher linear energy transfer (LET) are more effective in
producing biological effects
• HZE
• Low energy p+
• α-particles
• LET is the amount of energy that is released by radioactive material per
unit length
35 Memorial University
Radiation:
Biological Effects (Cont.)
34. Radiation:
Low-level Acute Radiation Exposure Models
36
• No evidence of adverse health effects
at chronic doses below 100 mSv
• Various models to estimate radiation
risk of low-level radiation exposure
• Hypersensitivity – Greater risk at low doses
• Linear No-Threshold – Linear relationship between
radiation exposure and cancer risk
• Threshold – Below certain doses, no cancer risk
• Hormesis – Low doses protective/beneficial
• Known risks represented by data points > 100 mSv
Canadian Nuclear Safety Commission (CNSC)
35. • Acute (rapid) Wholebody Absorbed Dose
– < 25 rad
• insignificant acute changes
– 25 - 50 rad
• temporary oligospermia
– 50 - 100 rad
• mild nausea in 5 - 30% of population
• mild vomiting in 5 - 20% of population
• anorexia in 15 - 50% of population
• slight decreases in lymphocyte, platelet, and
granulocyte counts--no overt symptoms
– 100 - 200 rad
• mild to moderate nausea in 30 - 70% of
population
• mild to moderate vomiting in 20 - 50%
of population
• slight to moderate decreases in
lymphocyte, platelet, and granulocyte
counts
• anorexia in 50 - 90% of population
• mild to moderate fatigue in 30 - 60% of
population
• mild bleeding in 10% of population
• mild to moderate fever/infection in 10-
50% of population
• death in less than 5% of population
Radiation:
Exposure Effects
37
36. • Acute (rapid) Wholebody Absorbed Dose
– 200 - 350 rad (cont.)
• moderate nausea in 70 - 90% of population
• moderate vomiting in 50 - 80% of population
• anorexia in 90 - 100% of population
• moderate diarrhea in ~ 10% of population
• moderate fatigue in 60 - 90% of population
• moderate weakness in 60 - 90% of population
• moderate bleeding in 10 - 50% of population
• moderate infection in 10 - 80% of population
• moderate epilation in 30% of population
• moderate decreases in platelets and granulocytes
• moderate to severe decrease in lymphocytes
• death in 5-50% of population
– > 350 rad
• death to 50% of population in 60 days (LD50/60)
Risk of acute effects during
Shuttle or ISS missions is
considered very minimal!
Radiation:
Exposure Effects (Cont.)
38
37. Type of Exposure
• Limit: Annual Canadian Public
• Limit: Annual Canadian Radiation Worker
• Average annual exposure to natural background
• Average annual occupational exposure (US) (ground)
• Living one year in Kerala, India
• Airline Flight Crew
• Apollo 14 Highest Skin Dose
• Average Shuttle Skin Dose
• STS 82 Highest Skin Dose
• STS-57(473 km, 28.5)
• STS-60(352 km, 57)
• 140 day mission on ISS (400 km, 51.56)
• 1 year in deep space(5 g cm-2
Al shielding)
• 1 year deep space(5 g cm-2
polyethylene shielding)
• Mars mission BFO Dose (GCR+SPE:behind 10 g cm-2
shielding) (3-year)
Radiation:
Levels of Exposure – Based on Occupation
Dose Equivalent
1 mSv/y
20 mSv/y
2.94 mSv/y
2.10 mSv/y
13 mSv/y
1-6 mSv/y
14 mSv
~4.33 mSv
76.3 mSv
19.1 mSv
4 mSv
~60 mSv
1140 mSv
870 mSv
800 to 2000 mSv
Ground
Air
Space
38. Regulations and Standards:
30 Day, Annual and Career Exposure Limits
Exposure
Duration
BFO – 5.0 cm
(Sv)
Eye – 0.3 cm
(Sv)
Skin – 0.01 cm
(Sv)
30 Days 0.25 1.00 1.50
Annual 0.05 2.00 3.00
Career 1.00 4.00 6.00
• 30-Day and annual exposure are for protection against deterministic
effects (short term effects)
• Career limit Stochastic effects (fatal cancer)
40
39. Regulations and Standards:
As Low As Reasonably Achievable (ALARA)
• Involves setting upper limits on the doses received
• Radiation exposures resulting from the practice must be reduced to lowest
levels possible; technological, economic and social issues considered
• Proposed activity that may cause exposure to humans should yield a
sufficient benefit to society to justify the risk
• Understanding and minimizing exposures from space weather events is
an important implementation of ALARA for manned missions
41
41. Radiation Monitoring:
Pre-, In-, and Post-Flight
• Pre-Flight
• Space radiation exposure assessment performed. Ensure exposures are within limits
(ALARA)
• Inter-Vehicular Activity (IVA) – Activities performed while inside ISS
• Extra-Vehicular Activity (EVA) – Activities performed while outside ISS
(Spacewalk)
• Space environment monitoring
43
42. Radiation Monitoring:
Pre-, In-, and Post-Flight
• In-Flight
• Ensure crew limits do not exceed prescribed limits (ALARA)
• Daily support and enhancements
• Post-Flight
• Determine crew exposure and risk
• Biodosimetry analysis
44
43. Est. 1962
ANALYSIS GROUP
J
S
CN
A
S
A
SPACE RADIATION
Radiation Monitoring:
Space Weather – Space Radiation Analysis Group
(SRAG)
• Provides projections for crew exposure
• Maintain comprehensive crew exposure modeling capability
• Radiation instruments to characterize and quantify radiation environment
inside and outside ISS and other spacecraft
• L-4 Months: Complete preliminary EVA exposure analysis
• Forward to Flight Surgeon and Radiation health Officer
• L-5 Weeks: Complete final analysis of EVA exposure from nominal environment
• L-4 Weeks: Report analysis for planned and contingency EVA exposures
45
44. • In-Flight support
• Provide appropriate alerts and warnings
• Daily space weather reviews and forecasts (via telecon)
• Weekly summaries of forecasts (via email)
• Solar forecasters (24/7 support)
• Classifies solar activity in conjunction with SRAG
46
Radiation Monitoring:
Space Weather – National Oceanic and
Atmospheric Association (NOAA)
45. • Receive real-time space environment data from variety of operational
stations, including:
• Satellites
• Geostationary Operational Environmental Satellites (GOES)
• Solar and Heliospheric Observatory (SOHO)
• NOAA/Television Infrared Observation Satellite Program (TIROS)
• Ground stations
• Ground-based solar observations,
• NASA science spacecraft
• United States Air Force (USAF)
47
Radiation Monitoring:
Space Weather – National Oceanic and
Atmospheric Association (NOAA)
46. • Solar classification uses a letter system which ranks solar activity by its
peak X-ray activity
• Letter denotes the order of magnitude of the peak value and the number is
the multiplicative factor
The SEC X-ray Flare Classification
Peak Flux Range (0.1 – 0.8 nm)
Classification SI Unit
(W/m2)
CGS Unit
(erg/cm2/s)
A φ < 10-7 φ < 10-4
B 10-7 ≤ φ < 10-6 10-4 ≤ φ < 10-3
C 10-6 ≤ φ < 10-5 10-3 ≤ φ < 10-2
M 10-5 ≤ φ < 10-4 10-2 ≤ φ < 10-1
X 10-4 ≤ φ 10-1 ≤ φ
48 CSA C1 Radiation Monitoring Plan
Radiation Monitoring:
NOAA – Solar Activity Classification
47. • Geomagnetic storm – temporary disturbance of Earth’s magnetic field
• Two different classes to describe geomagnetic activity
• A-index: 24 hr average level
• K-index: 3 hr interval
• Quantifying disturbances in horizontal component of Earth’s magnetic field
• Derived from maximum fluctuations of horizontal components observed
Category A-Index K-Index
Quiet 00 ≤ A < 08 Usually no K indices > 2
Unsettled 08 ≤ A < 16 Usually no K indices > 3
Active 16 ≤ A < 30 A few K indices of 4
Minor Storm 30 ≤ A < 50 K indices mostly 4 and 5
Major Storm 50 ≤ A < 100 Some K indices 6 or greater
Severe Storm 100 ≤ A Some K indices 7 or greater
49 CSA C1 Radiation Monitoring Plan
Radiation Monitoring:
NOAA – Geomagnetic Activity Classification
48. • X-Ray Flare
• SPE*
• ≥ 10 pfu @ ≥ 10 MeV
• Energetic SPE
• ≥ 1 pfu @ ≥ 100 MeV
• Major Geomagnetic Storm
• AB ≥ 50
• KB = 6
* pfu (proton flux unit)
pfu = particles/sr/cm2/s
• Major X-Ray Flare
• ≥ M5
• Major Integral X-Ray Event
• Flux ≥ 0.3 W/m2
• SPE
• ≥ 10 pfu @ ≥ 10 MeV
• Energetic SPE
• ≥ 1 pfu @ ≥ 100 MeV
• Major Geomagnetic Storm
• AB = 50 – 99
• KB = 6
• Severe Geomagnetic Storm
• AB ≥ 100
• KB ≥ 7
SRAG recall to Mission Control
** Alert product still in development
SRAG remain on console
Radiation Monitoring:
SRAG and NOAA Warning and Alert Criteria
Watches/Warnings Alerts
50
51. • 3-axis unit mounted to mast on S0 truss of ISS
• EV1 – Forward along velocity vector (direction of orbit)
• EV2 – Zenith direction (orthogonal to ISS)
• EV3 – Along anti-velocity vector (opposite to EV1)
• Thresholds of measured charged particles
• Proton ≥ 15 MeV
• Electron ≥ 0.5 MeV
• Records dose and dose rate values
53
Radiation Monitoring:
Extravehicular Charged Particle Directional
Spectrometer (EV-CPDS)
52. • Unit insensitive to neutrons
• Measured particle flux as a function of particle energy, charge and arrival
direction
• Trapped
• Secondary
• GCR
• Data sent directly to mission control
54
Radiation Monitoring:
Extravehicular Charged Particle Directional
Spectrometer (EV-CPDS)
54. • Identical to single axis EV-CPDS unit
• Portable
• Used to conduct shielding effectiveness surveys
• Not suitable for monitoring important low-energy component of EVA
exposures
56
Radiation Monitoring:
Intravehicular (Internal) Charged Particle
Directional Spectrometer (IV-CPDS)
56. • Active system which provides measurements of dose rate and cumulative
dose at 2 or 20 second intervals
• Not suitable for monitoring important low-energy component of EVA
exposures
• Located inside ISS. Moved throughout the station approximately every
month
58
Radiation Monitoring:
Tissue Equivalent Proportional Counter (TEPC)
57. • Time resolved Linear Energy Transfer (LET) spectra
• 0.3 – 1200 keV/m
• Alarm capability when dose rate exceeds 5 mrad/min (50 Gy/min) –
Absorbed dose
• Dose and dose equivalent are stored for future analysis
59
Radiation Monitoring:
Tissue Equivalent Proportional Counter (TEPC)
58. • Thermoluminesent dosimeters (TLDs) placed throughout the ISS
• Dose is determined upon further analysis once the detectors are returned
to Earth
• No record of LET information from charged particles
• Archived measurements are available in
• Absorbed Dose – H2O (mGy)
• Absorbed Dose Rate – H2O (Gy/day)
60
Radiation Area Monitor – SRAG
Radiation Monitoring:
Radiation Area Monitor (RAM) and
NASA Crew Passive Dosimeter (CPD)
59. • Sensitive to neutrons and charged
particles and records particle impact
angles and LET information
• Consists five different passive
radiation sensors
• Designed to measure total
absorbed dose
61
Radiation Monitoring:
European CPD (EuCPD)
CSA C1 Radiation Monitoring Plan
60. •Acquires two sets of data
• Shielded
• Unshielded
• Measurements updated through the SRAG website and can be acquired
for specific dates
62
Radiation Monitoring:
DB-8 Detectors
CSA C1 Radiation Monitoring PlanCSA C1 Radiation Monitoring Plan
61. Protection Against Ionizing Radiation onboard ISS
• During periods of higher radiation activity, it is always best to stay in
high shielded areas to reduce exposure
Higher Shielded areas of ISS
• Service Module aft of treadmill (Panel 339)
• Node 2 crew quarters
• US Lab
Lower Shielded areas of ISS
• Service Module crew sleeping compartments
• Service Module transfer compartment (between FGB and Service Module)
• Pressurized mating adapters
• Air locks
• Window in US Lab (WORF)
63
62. Protection Against Ionizing Radiation:
Module Locations
US Destiny Laboratory
Module (US LAB)
Japanese Experiment
Module (JEM/Kibo)
ESA Columbus
Module (COL)
Russian Zvezda
Service Module
64
65. • Individual responses governed by genetic variability and results in a wide
range of susceptibilities and risks
• A number of tests are performed on the samples including:
• Fluorescent in situ Hybridization (FISH)
• Spectral Karyotyping (SKY)
• Cytokinesis Block Micronucleus (CBMN) Assay
• Dicentric Chromosome Assay
• Protein Profiling
• In addition to the tests listed above, data is also collected from physical
dosimetry devices for comparison.
67
Radiation Monitoring:
Biodosimetry
66. Radiation Monitoring:
Biodosimetry – Fluorescence in situ Hybridization
(FISH)
• An effect of ionizing radiation is when “stable” translocations occur
• Chromosome segments are exchanged, but no genetic information is lost
• These abnormalities are not lethal
• FISH provides a measure of cumulative lifetime dose
• Translocation rates are determined by fluorescently labeling parts of the
genome with part of the segments appearing bi-colored
68
68. Radiation Monitoring:
Biodosimetry – Spectral Karyotyping (SKY)
• Similar to FISH, SKY allows you to visualize all 23 pairs of human
chromosomes at one time
• Differs in the methods it employs to detect and discriminate the different
colour combinations
• Each probe is labeled with a fluorescent molecule that corresponds to the
chromosome to which it is complementary
• Probes complementary to chromosome 1 are labeled yellow, chromosome 2 red, and
so on…
70
69. 71 Health Canada
Health Canada
Radiation Monitoring:
Biodosimetry – Spectral Karyotyping (SKY)
70. Radiation Monitoring:
Biodosimetry – Cytokinesis Block Micronucleus
(CBMN) Assay
• Micronuclei are formed when a complete chromosome or a fragment is
not incorporated into one of the daughter nuclei during cell division
• Proliferating and non-proliferating cells may be distinguished
• Micronuclei are only scored in binucleated cells
• Dose estimation may be correlated to micronucleus frequency
72
72. Radiation Monitoring
Biodosimetry – Dicentric Chromosome Assay
• Dicentric chromosomes form when two segments (from different
chromosomes) fuse, each with a centromere
• These chromosomes are unstable and so these tests only provides a
measure of DNA damage for the lifetime of the circulating lymphocyte
(type of white blood cell)
• Relatively specific to ionizing radiation
• Low energy radiation does not induce dicentrics
74
74. Radiation Monitoring
Biodosimetry – Protein Profiling
• Refers to quantifying the abundance of individual proteins in a sample
• Known as expression levels
• Current research is interested in identifying biomarkers that could be used
to evaluate an individual’s biological response to radiation exposure
76
75. Radiation Monitoring
Biodosimetry – Dose Response Curve
• Aberrations such as dicentric
chromosomes and translocations
are equally likely outcomes of
radiation exposure
• Individual dose estimates
derived by comparing aberration
rates to calibration curves
established by irradiating pre-
flight samples with known
radiation sources
77
Health Canada
77. Non-ionizing Radiation
• Consists of the broadband of electromagnetic radiation having
frequencies less than approximately 3 – 1015 Hz, or expressed in
wavelength 108 – 10-7 m
• Far end of the ultraviolet spectrum (10-15 Hz) is considered ionizing
radiation
• Heat generation is consider the main biological effect of non-ionizing
radiation
79
80. Summary
• Ionizing radiation can cause atoms and molecules to become electrically
charged and damage DNA
• Astronauts are exposed to ionizing radiation on ALL space flights
• Galactic Cosmic Rays (GCR)
• Solar Particle Events (SPE)
• Trapped Particles – Van Allen Radiation Belts
• Secondary Particles
• Low-level radiation exposure follows the Linear No-Threshold Model
• Acute biological effects of space radiation (with the exception of SPE) are
not expected to result from radiation exposure in space.
82
81. Summary
• Radiation exposure can result in an increased risk in cancer (stochastic
effects)
• Those who are exposed to radiation in LEO receive a dose from various
types of radiation sources (neutrons, protons, gamma-rays, etc).
• Ionizing radiation exposure can leave distinct markers in the blood
samples taken from individuals who have been exposed
83
82. Summary
84
• Further studies will be conducted in order to characterize neutron
radiation field during ISS-34/35 during the Radi-N2 study
• The ALARA protocol is followed at ALL TIMES
• Astronauts are asked to wear the their CPDs to monitor their dose at ALL
TIMES
83. 85
Sources
1. B. W. Glickman Consulting.(n.d.).BiomonitoringRadiation Effects in Astronauts in Space: A Canadian Perspective.Victoria, British Columbia,Canada.
2. Emigh, B. (2007, April 27).Radiation ExposureDuringSpace Missions:Briefingfor Canadian Astronauts.Saint-Hubert,QC, Canada.
3. Golightly,M. (1999, June 10). Initial Briefingto Astronauts:Radiation ExposureDuringSpaceMissions.Houston,Texas,United States of America.
4. International SpaceStation Multilateral Medical OperationsPanel (ISS MMOP).(2010). Medical Evaluation Documents (MED) Volume B. International Space
Station Multilateral Medical OperationsPanel (ISS MMOP).
5. Kiefer, J. (n.d.). Radiation Risksto Astronauts.Giessen,Germany.
6. Koontz, S. L., Boeder, P. A., Pankop, C., & Reddell,B. (2005). The IonizingRadiation Environmenton the International Space Station: Performance vs.
Expectations for Avionics and Materials. IEEE , 110-116.
7. Lewis, B. J. (2011,February 11). Aircrew and Spacecrew Radiation Exposure"The Dangers of Getting High". Kingston,Ontario, Canada.
8. Lewis, B. J., Smith, M. B., Ing, H., Andrews, H. R., Machrafi,R.,Tomi, L., et al.(2011). Review of Bubble Detector Respons e Characteristicsand Results from
Space. Radiation Protection Dosimetry , 1-21.
9. Massachusetts Instituteof Technology. (2006). The Radiation Environment in Space. Retrieved November 16, 2011, from http://ocw.mit.edu/courses/nuclear-
engineering/22-01-introduction-to-ionizing-radiation-fall-2006/lecture-notes/space.pdf
10. National Aeronautics and SpaceAdministration.(2005). Man-Systems Integration Standards. Houston.
11. National Aeronautics and SpaceAdministration.(1994). Space Station Ionizing Radiation Design Environment. Houston: National Aeronautics and Space
Administration.
12. National Council on Radiation Protection and Measurements. (1989). Guidance on Radiation Recieved in Space Activities. Bethesda: National Council on
Radiation Protection and Measurements.
13. Ng, K. -H. (2003). Non-IonizingRadiations - Sources,Biological Effects,Emissions and Exposures. International Conference on Non-Ionizing Radiation at UNITEN,
(pp. 1-16). Kuala Lumpur.
14. Smith, M. B., Akatov, Y., Andrews, H. R., Arkhangelsky,V., Chernykh, I. V., Ing, H., et al.(2011).Measurements of the Neutron Dose and Energy Spectrum on
the International SpaceStation DuringExpeditions ISS-16 to ISS-21. Radiation Protection Dosimetry (Submitted for Publication) .
15. SRAG/JSC. (n.d.). Radiation Familiarization.Houston,Texas.
16. Tchistiakova,E., & Tomi, L. (2009). C1 Radiation Monitoring. Saint-Hubert.
17. Tchistiakova,E., & Tomi, L. (2009). Radi-N - Radiation Neutron Study. Saint-Hubert.
18. Wilkins,R.(2011).Biodosimetry Programme: For AstronautRadiation DoseAssessment. Ottawa.
19. Windows to the Universe. (2008, January 23). Cosmic Rays. Retrieved November 1, 2011,from
http://www.windows2universe.org/physical_science/physics/atom_particle/cosmic_rays.html
20. Zapp, N. (n.d.). Space Radiation Operations:Status,Methods and Needs. Houston, Texas, United States of America.
