VIRTUS stands for the VIrtual Radiation Training through Ubiety System. Ubiety is "the state of being placed in a definite local relation." Ubiety is foundational to the VIRTUS methodology. Whether through GPS or Bluetooth beacons, VIRTUS determines the relative positioning, or ubiety, of radiation sources and detectors. With this information, detector responses can be simulated..
The Defense Threat Reduction Agency is the Department of Defense agency that provides chemical, biological, radiological, nuclear, and high-explosive (CBRNE) technical advice, assistance, and support to the Secretary of Defense, the Services, and Combatant Commanders. Conceived in the Defense Threat Reduction Agency’s J9 directorate, VIRTUS intends to overcome many of the shortfalls of simulation support to training in general, and radiation training specifically. The Roman solider embodies this ethos with virtus. In Ancient Rome, virtus was a discrete virtue, and it combined the modern concepts of valor, courage, and character. These are values of the United States military and first responders, who comprise the VIRTUS user community.
The best radiation detector training is conducted with real radioactive sources and real detectors. However, regulations on the transport and deployment of radioactive material severely limit the locations in which radiation training can be performed. Plus, military and first responder personnel often do not have unlimited access to the radiation detectors that would be issued during a real-world emergency. The Defense Threat Reduction Agency (DTRA) created the Virtual Radiation Training through Ubiety System (VIRTUS) to provide realistic, low-cost training by leveraging Commercial Off The Shelf (COTS) mobile computation capabilities. VIRTUS is a suite of Android apps, and it can run on most Android phones and tablets.
Simulated dose rates and other measurements are determined based on the Android device's GPS position. Additionally, Bluetooth beacons have been integrated as surrogate radiation sources, facilitating indoor operations and increased accuracy. Nuclear fallout environments are modeled using standard industry codes. The user interfaces and approximations for the physical behaviors of the Mirion Technologies UltraRadiac™ (AN/UDR-13/14/15), the Thermo Scientific RadEye™ PRD-ER, PackEye™, and FLIR Systems IdentiFINDER radiation detectors were incorporated into VIRTUS, and additional detectors are planned.
The Map App allows the user to place point sources on the map by touching the screen. A number of different sources approved by the Department of Energy have been modeled, including special nuclear material, medical patients, and industrial sources. The Map App also includes a "fingerpainted rad-map" capability, which allows the user, by rubbing his or her finger on the screen, to specify regions of elevated radiation emission. The longer the finger is held on a spot, the greater the magnitude of the radiation at that spot will be. The user can then define the radiation emissions to which the colors correspond. The user can also change between linear and logarithmic scaling. These fingerpainted rad-maps can be used to approximate heterogeneous radiation background regions and radioactive plumes.
GPS positioning provides a baseline capability for VIRTUS, but GPS isn't effective indoors. For indoor operations, Bluetooth beacons can be used. The beacons utilize a relatively new Bluetooth standard called Bluetooth Low Energy (BLE), also known as Bluetooth 4.0 and Bluetooth Smart. The BLE standard has been adopted by a number of smartphone and tablet manufacturers. BLE devices require very little energy—a single beacon can have a battery life greater than a month, even with continuous use. Each beacon is about the size of a coin, similar to check sources used in the radiation detector industry. The beacons are set to emit data packets at 10 Hz. Each beacon always emits its signals at the same intensity. A VIRTUS device determines its approximate distance from a given beacon by measuring the strength of the signal received. Like with γ-rays, the RF signal intensity from a beacon drops off according to the squared inverse of the distance. The attenuation properties of RF are different than those of γ-rays, but the behaviors are similar enough for reasonably effective training.
Four radiation detectors have been simulated in VIRTUS. Handheld systems include the Mirion Technologies UltraRadiac™ (AN/UDR-13/14/15) and the Thermo Scientific RadEye™ PRD-ER. These two hip-mounted devices are used by military, first-responder, and industry personnel worldwide. The Thermo Scientific PackEye™ is a backpack system, and the handheld indicator module (left) has been integrated. The PackEye can detect both γ-rays and neutrons, and the two functionalities are simulated in VIRTUS. VIRTUS simulates a hand-held spectrographic system called the FLIR Systems IdentiFINDER. The IdentiFINDER simulation exhibits detection and isotope identification behavior similar to the actual device.