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Organ Dose Measurement Using the Phantom Torso (Torso)
02.06.09

Overview | Description | Applications | Operations | Results | Publications | Images

Experiment/Payload Overview

Brief Summary

Organ Dose Measurement Using the Phantom Torso (Torso) measured the amount of radiation that a human received during an extended space flight. The measurements were taken using an anatomical model of a male head and torso that contains different types of radiation sensors. This experiment is important for future human long-duration space exploration.

Principal Investigator

  • Gautam D. Badhwar, Ph.D., Johnson Space Center, Houston, TX

    • Co-Investigator(s)/Collaborator(s)

  • Francis Cucinotta, Ph.D., Johnson Space Center, Houston, TX

    • Payload Developer

    Johnson Space Center, Human Research Program, Houston, TX

    Sponsoring Agency

    National Aeronautics and Space Administration (NASA)

    Expeditions Assigned

    |2|

    Previous ISS Missions

    Information Pending

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    Experiment/Payload Description

    Research Summary

    • This experiment uses a synthetic human torso, embedded with over 300 strategically placed dosimeters (radiation sensors), to determine the levels of cosmic radiation absorbed by specific organs in the human body during space flight.


    • Two types of sensors are used:
      • passive sensors will quantify the total amount of radiation absorbed in various body parts throughout the entire flight.

      • active sensors will give real time data describing how much radiation is absorbed at varying times during ISS orbit.


    • Real time data will focus on the brain, thyroid, colon, and stomach.

    Description

    One of the most critical risks to humans in space is radiation exposure. Outside the protection of Earth's atmosphere, space crews are exposed to a wide range of particles, including neutrons, that are not normally a threat on Earth. Exposure to radiation found in low Earth orbit (LEO) and beyond can cause cataracts, cancer, damage to reproductive organs and the nervous system, and changes in heredity.

    The Organ Dose Measurement Using the Phantom Torso (Torso) employed a model human head and torso (Rando phantom), imbedded with over 350 detectors (thermo-luminescent detectors) and five silicon diode detectors, over five depths to measure absorbed dose to specific organs during shuttle flight. A tissue equivalent proportional detector and a charged particle directional spectrometer were placed within 1.5-feet of the torso during these ISS measurements. This was the first NASA experiment to simulate doses at discrete locations within the body.

    The tissue equivalent proportional counter (TEPC) consists of a spectrometer and cylindrical detector with which to measure external radiation doses. The TEPC measures radiation dose and dose equivalent in complex radiation fields (fields containing a mixture of particle types). The charged particle directional spectrometer (CPDS) measures particle energy and direction inside ISS. Both the TEPC and the CPDS remained within 1 - 1.5 feet (30.48 - 45.72 cm) of Torso during its operation on station.

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    Applications

    Space Applications

    The Torso experiment will help scientists more accurately predict the radiation exposure astronauts will experience inside their bodies, especially to critical blood-forming organs. No previous experiment has had the capacity to measure radiation doses in multiple, discrete locations in the body. By performing this experiment on board the International Space Station, scientists also will learn how long human beings can remain in space before the body absorbs dangerous levels of radiation. The experiment may lead to protective procedures to safely prolong human exposure to radiation.

    Earth Applications

    There are benefits on Earth, as well. This experiment is teaching scientists more about the use of embedded devices for data collection and how to monitor real-time data. This could prove beneficial to radiation monitoring of commercial airline crews and military flight crews.

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    Operations

    Operational Requirements

    The crew was only required to transfer and activate the Torso and equipment, check its status every 7 to 10-days, download data (using the Human Research Facility - 1 laptop) every 7 to-10 days, and to change the battery every 20-days. At the completion of the experiment, the crew disassembled the Torso for its return on STS-105.

    Operational Protocols

    The crew set up the Torso in the U.S. Destiny Laboratory and activated all the associated hardware. Once activated, the Torso, CPDS, and TEPC collected data continuously, without crew intervention. Data downloads were sent to the Telescience Center at Johnson Space Center for distribution to the investigators.

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    Results/More Information

    Organ Dose Measurement Using the Phantom Torso (Torso) results were combined with results from various experiments on previous missions to validate NASA's organ dose database for astronauts. Preliminary results suggest that organ dose and dose equivalent can be projected to a +/- 25 percent accuracy using a combination of dosimetry and radiation transport models. This accuracy envelope is greatly improved relative to the current accuracy of organ specific cancer risk projections, estimated at +/- 500 percent. Further analyses and incorporation of these radiation results into operational planning for exploration is ongoing.

    Overall, the dose rates measured in Torso were in good general agreement with other measured values and with the models used to predict these values. The largest differences observed between measured data and the simulations were 15 percent. In addition, a model which considers orbital altitude, attitude, and solar cycle emissions agreed within 25 percent of the measured data. It was determined that the majority of radiation energy deposited in human tissues (about 80 percent) was due to galactic cosmic radiation. This is due to spacecraft material providing effective attenuation of the protons trapped in the Earth's magnetic field. The data indicated an average radiation quality factor (a measurement of how damaging a type of radiation is to tissue) of 2.6 and that the quality factors do not appreciably change with depth in the body. Finally, this experiment indicated that the contribution to both skin and organ doses from secondary neutrons is not negligible (Expedition 2 Postflight Report).

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    Related Web Sites
  • Life Sciences Data Archive
  • Science @ NASA
  • NASA Fact Sheet
  • International Space Station Medical Project

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    Publications

    Results Publications

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      Related Publications
      • Badhwar GD, O'Neill PM. Response of silicon-based linear energy transfer spectrometers: implication for radiation risk assessment in space flights. Nuclear Instruments & Methods in Physics Research. Section A. ;466(3):464-474. 2001
      • Badhwar GD. Shuttle radiation dose measurements in the international space station orbits. Radiation Research. ;157(1):69-75. 2002
      • Badhwar GD, Atwell W, Badavi FF, Yang TC, Cleghorn TF. Space radiation absorbed dose distribution in a human phantom. Radiation Research. ;157(1):76-91. 2002
      • Badhwar GD, Robbins DE, Gibbons F, Braby LA. Response of a tissue equivalent proportional counter to neutrons. Radiation Measurements. ;35(6):551-556. 2002
      • Wilson JW, Shinn JL, Tripathi RK, Singleterry RC, Clowdsley MS, Thibeault SA, Cheatwood FM, Schimmerling W, Cucinotta FA, Badhwar GD, Noor AK, Kim MY, Badavi FF, Heinbockel JH, Miller J, Zeitlin C, Heilbronn L. Issues in deep space radiation protection. Acta Astronautica. ;49(3-10):289-312. 2001
      • Kolomenskii AV, Kuznetsox VG, Laiko IA, Bengin VV, Shurshakov VA. The model of radiation sheilding of the service module of the International Space Station. Aviakosm Ekolog Med. ;35(6):39-43. 2001
      • Berger T, Hajek M, Schoner W, Fugger M, Vana N, Noll M, Ebner R, Akatov Y, Shurshakov V, Arkhangelsky V. Measurement of the depth distribution of average LET and absorbed dose inside a water-filled phantom on board space station Mir. Physica Medica. ;17 Suppl 1:128-130. 2001
      • Wilson JW, Cucinotta FA, Kim MH, Schimmerling W. Optimized shielding for space radiation protection. Physica Medica. ;17 Suppl 1:67-71. 2001
      • Edwards AA. RBE of radiations in space and the implications for space travel. Physica Medica. ;17 Suppl 1:147-152. 2001

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      Images

      imageNASA Image: ISS002E5952 - Image of the Torso on ISS during Expedition 2.
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      imageTorso is an anatomical model of a torso and head containing more than 300 radiation sensors. Image courtesy of NASA.
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      Information Provided and Updated by the ISS Program Scientist's Office
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