AUSHEP 2004 UoW

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AUSHEP 2004 UoW MIDN A SPACECRAFT
MICRODOSIMETRY MISSION   Rosenfeld, A.B.1
Cornelius,I 1., Wroe, A 1., Lerch,M 1.,
Pisacane, V. L..2 Ziegler, J. F.2 Nelson,
M.E.2 Caylor, M.2 Flake, D.2 Heyen,
L.2 Youngborg, E.2 Cucinotta, F.2 Zaider, M.4,
Dicello, J. F.5,2 1University of Wollongong,
Wollongong, Australia 2United States Naval
Academy, Annapolis, MD 3NASA Johnson Space
Center, Houston, TX 4Memorial Sloan-Kettering
Cancer Center, New York, NY 5Johns Hopkins
University School of Medicine, Baltimore, MD
Supported in part from NASA Project RE00203 award
from NASA/National Space Biomedical Research
Institute
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The most critical health risks, those classified
by NASA as ranked as 1(I), are

• ______________________________________________
• Carcinogenesis caused by radiation
• Loss of bone mass or density
• Human Performance Poor psychosocial adaptation
• Clinical Manifestations Trauma or acute medical
  problems
• NASAs Critical Path Roadmap (April, 2003)

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Dicello et al., 2003
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Dicello and Cucinotta, Encyclopedia of Space
Science and Technology, 2002
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Space station astronauts take shelter from solar
radiation
Crew retreats to module with more shields during
unusually severe flares
By Frank D. Roylance, Baltimore Sun Staff
Originally published Nov 11, 2000
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Cucinotta et al
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RELEVANCE OF PRESENT RESEARCH TO DEVELOP A
SPACE-COMPATIBLE SOLID-STATE MICRODOSIMETRY SYSTEM

• Cancer risks from radiation are almost
  universally determined from microdosimetric or
  LET spectra.
• Present methods for obtaining spectra use either
  tissue-equivalent gas proportional counters
  (TEPCs) or plastic track detectors.
• However, plastic track detectors must be
  recovered and processed. The microdosimetric
  tissue-equivalent proportional counters in the
  NASA Space program have been delicate and
  unreliable, and the results have been
  inconsistent.

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OBJECTIVE

• Our goal is to develop a
• rugged,
• compact,
• low-power,
• reliable,
• Solid-state microdosimeter that can measure the
  information needed to obtain dose equivalents in
  the harsh environments in Space.

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• NCRP HAS RECOMMENDED THAT RISKS IN SPACE CONTINUE
  TO BE STATED IN TERMS OF THE
• DOSE EQUIVALENT The product of the physical dose
  and the quality factor for a specific type of
  radiation (Zaider and Dicello, 2003)
• DEQ QF(LTE)D
• or
• DEQ QF(yTE)D
• QF REPRESENTS THE BIOLOGICAL FACTORS
  AFFECTING THE RISK AS DEFINED BY ICRU 40 AND ICRP
  60
• D REPRESENTS THE PHYSICAL FACTORS AFFECTING THE
  RISK.

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• IN OUR CASE, WE MUST DEVELOP A METHOD FOR GOING
  FROM MEASUREMENTS IN SILICON TO RISK IN HUMANS
• DEQ QF(ySi)D
• QF REPRESENTS THE BIOLOGICAL FACTORS AFFECTING
  THE RISK.
• D REPRESENTS THE PHYSICAL FACTORS AFFECTING THE
  RISK.

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Dicello, Wasiolik, and Zaider, IEEE Trans (1991)
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COMPARISONTEPC and Microdosimeter
I. Cornelius, A. B. Rosenfeld, P. D. Bradley,,
and R. L. Maughan, A Computational Technique for
Simulating Ionization Energy Deposition by
Energetic Ions in Complex Targets, IEEE
Transactions On Nuclear Science, Vol. 47, No. 6,
December 2000
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• MidSTAR Spacecraft

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MIDN Locations
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MidSTAR Configuration
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MICRODOSIMETER SENSOR
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IMMEDIATE RESEARCH GOALS

• Ground-based design and development
• Ground-based testing including exposure to
  energetic heavy ions (HZEs) at the Brookhaven
  National Laboratory
• Satellite-based Flight Experiment
• Develop MARS package for NASA Rover mission

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Microdosimetry Experiments and Simulations

• Shielding for spacecraft and satellites needs to
  be developed for extended deployment periods
• Biological Effects to personnel need to be
  minimised whilst also minimising weight
• Shielding can be both theoretically and
  experimentally tested using microdosimetry methods

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Microdosimetry Experiments

• Microdosimetry experiments with the
  microdosimeter at different positions within the
  phantom gives information of spectra of
  secondaries at material boundaries
• This provides information for both shielding and
  biological materials
• Experiments are to be carried out for different
  layered heterogeneous structures at LLUMC in 2005

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Microdosimetry Simulations

• MC simulations once verified provide a powerful
  tool for non destructive testing of shielding
  configurations
• GEANT4 will be used to simulate layered
  biological and shielding materials
• Studies will help further validate GEANT4
  transport algorithms
• Spectra of space radiation will be used for the
  input for this program

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Microdosimetry Simulations
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REMAINING ISSUES

• NEED TO DESIGN AND BUILD A SYSTEM THAT IS SPACE
  QUALIFIED,
• NEED TO REDUCE THE NOISE TO BE ABLE TO MEASURE
  ALL OF THE LOW-ENERGY EVENTS (LOW LET),
• NEED TO REDUCE THE DIMENSIONS OF THE INDIVIDUAL
  CELLS,
• NEED TO DEVELOP METHODS TO GO FROM SPECTRA IN
  SILICON TO DOSE EQUIVALENT IN TISSUE.

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Long-Term Goal

• Determine the risk of cancers for the particles
  in Space, in order to more accurately determine
  the actual biological risk.
• Toward that end, we have been carrying out the
  first comprehensive study of the risks of cancers
  in animal models that can be best extrapolated to
  humans.
• We are concurrently carrying out in-vivo studies
  of pharmaceutical protectants that can be
  administered after exposure to reduce the risks.

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