Citizen dosimeter may become hot propertyDHS comes up with credit card-sized personal radiation sensor
By Doug Page
Soon, first responders, second responders and regular citizens can reach in their pockets for a credit card-sized dosimeter to gauge exposure to ionizing radiation in the event of a nuclear accident or dirty bomb.
The high-tech device, called the Citizen's Dosimeter, was developed by the Department of Homeland Security to provide a convenient and affordable way to measure the amount of radiation on a person or in a particular area.
"The purpose of personal dosimetry is to avoid potential long-term health effects from radiation exposure," DHS physicist Gladys Klemic told Homeland1.
Klemic said the patented device has a unique combination of features, including a wide sensitivity range (10 mrad — 1,000 rad), the ability to store cumulative dose information, a re-usable field readout capability in a familiar credit card format and low cost.
Most current large-scale radiation worker dosimetry programs require users to return their dosimeters to a laboratory for processing. "This new DHS device would allow users to periodically check their own dose in strategically positioned card readers," Klemic said.
As a homeland security tool, Klemic said, the dosimeter would be applicable in the aftermath of a radiological event such as a dirty bomb in a densely populated urban area.
"It would be appropriate for applications that do not require alarming functions as would be needed to alert on acute doses of high-level radiation and could be used for a large-scale dosimetry program," Klemic said.
Klemic said first responders could use it to complement alarming electronic devices in order to monitor their personal long-term accumulated dose. It would also be applicable for secondary responders who might be working in areas with elevated or residual radiation levels or for members of the public moving through potentially contaminated areas.
"Dose readers combined with interlocking gates could even be designed for access control," she said.
The radiation-sensitive material inside the Citizen's Dosimeter is an optically stimulated luminescence (OSL) material made by Landauer Inc., Glenwood, Ill., which uses the material in its Luxel line of dosimetry devices made for radiation workers.
The OSL material requires filters to achieve the correct dosimetry response across a spectrum of radiation energies. Klemic said DHS found a combination of materials to achieve filtering with a thinner profile than existing devices, making it feasible now to incorporate the dosimeter into a plastic card format.
A final prototype has not yet been built, but a workable blueprint for a wallet-sized card that can detect radiation in real time is now in place, Klemic said.
The next step is to transition the project to industry and academic partners for development of a prototype design of the dosimeter package, and the associated mechanisms required for the reader to access the sensitive element, she said.