Prior to the advent of the 360 Gamma, there was no effective personal protection from gamma radiation. In Chernobyl, first responders wore makeshift lead sheeting for protection. In Fukushima, emergency personnel undertook disaster mitigating activities without any protection from gamma radiation. In order to shield as much of the body as possible, past personal shielding solutions used only thin layers of inherently heavy radiation-attenuating materials. These types of solutions are ineffective in blocking energetic gamma radiation.
Receiving a high dose of gamma radiation over a short period of time may result in Acute Radiation Syndrome (ARS); protracted exposures to gamma radiation may result in malignancies such as leukemia. In the case of high-dose exposure, the survival-limiting factor up to doses of 10 Gy is irreversible bone marrow (BM) damage. Notably, in past radiological catastrophes doses were largely under 10 Gy. Thus, numerous fatalities may be avoided by protecting BM, even in the harshest of scenarios. Remarkably, due to its extraordinary regenerative potential, it is enough to protect only a small fraction of BM to preserve its recuperative function. In fact, only 2.5% of bone marrow must survive after radiation exposure in order to allow survival of the individual. This amazing regenerative capacity of bone marrow is exemplified in transplantation:
In the case of protracted exposure, BM is very susceptible to carcinogenesis. Thus, exposure of large areas of BM to radiation significantly increases the risk of leukemia. Approximately 50% of the of the body’s active BM is contained within the pelvic region. Thus, shielding this region holds great promise for both high dose and protracted exposures. The 360 Gamma is a device that even at extremely high radiation doses is able to protect a critical mass of BM sufficient for hematopoietic reconstitution – thereby preventing lethal ARS.
Equipping responders with this novel device offers dramatic improvements to survivability even under extreme radiological scenarios in which prevention of exposure to high dose radiation fails (see figure below). This device is also effective in reducing the cumulative marrow dose over the lifetime of the wearer, if used while performing tasks with potentially abnormal gamma exposures. As such, it may be used to protect professionals in a variety of occupations ranging from gamma radiography to agricultural sterilization.
Radiation doses to the human body in space result from of prolonged exposure to galactic cosmic rays (GCR) and periodic solar particle events (SPE). SPE are of concern due to their short warning times and high intensities. In 1972, between the Apollo 16 and 17 missions, an SPE capable of delivering high doses occurred. For future manned missions beyond Low Earth Orbit, the necessity for radiation protection increases along with mission duration as both the cumulative doses will increase with time as well as the probability of encountering a significant SPE. In spaceflight, efficient use of mass is crucial, and the development of a radiation shielding strategy, which offers a ratio of protection to mass, is required. The AstroRad personal shield utilizes a strategy which is based on innovative passive shielding worn by astronauts to maximize the solid angle of coverage while selectively protecting those tissues which are most radiosensitive. Some tissues disproportionately influence the effective dose through their high tissue weighting factors, such as bone marrow, stomach, lungs, glandular breast tissue, colon and gonads. Furthermore, focusing protection on tissue resident stem cells within these organs provides even greater benefit as they give rise to a disproportionately large number of daughter cells, so a stem cell with a radiation-induced mutation gives rise to thousands of mutated daughter cells, increasing the likelihood of cancer within that organ exponentially (see below figure). Simultaneously, stem cells possess a high capacity for tissue regeneration post-exposure, which is especially applicable to acute exposures.
Selective protection of these tissues was accomplished by designing the shielding thickness to be inversely related to the thickness and radiodensity of the underlying tissue at each point and point surrounding the targets for protection. Low-Z materials, especially materials with high hydrogen content, exhibit the largest mass stopping power and present low cross-section for generation of secondary radiation including neutrons. Therefore, low-Z materials are used in a vest-like design in order to provide a high ratio of reduction in effective dose to shielding mass. Novel nanomaterials are being investigated for inclusion in the AstroRad, and the design team has developed innovative ergonomic concepts which ensure user comfort and flexibility.
In a tri-national effort between the Israel Space Agency, German Aerospace Center (DLR) and NASA, AstroRad will be examined aboard Orion’s EM-1 lunar mission. The German Aerospace Center (DLR) will contribute their “Matroshka” human models, containing thousands of radiation detectors. “Matroshka” will wear the AstroRad vest alongside a “Matroshka” without a vest. Upon the return of Orion to Earth, teams from NASA, DLR and ISA will perform a comparative analysis on the efficacy of AstroRad.
“Israeli technology in space exploration is known as innovative, resulting from ‘out of the box’ thinking. We are proud to provide this technological breakthrough and become partners of one of the most exciting experiments of mankind in the coming years.” Minister of Science Ofir Akunis on AstroRad.
Additionally, the Israel Space Agency recently signed an agreement with Lockheed Martin Space Systems Company to launch AstroRad to the International Space Station (ISS) in 2019. Astronauts on ISS will wear the vest during their daily routine at the station for the purpose of ergonomic evaluation under the auspices of the US National Laboratory there (CASIS).