First responders deal with an almost unimaginably wide range of hazardous environments, and radiation detection technologies have been developed to better meet the challenges those environments present. Using the right response equipment can save lives; using the wrong equipment can endanger them. Understanding the differences in equipment can improve the odds of a quick and successful response and minimize risk to both responders and those in the vicinity of an event.

A personal radiation detector is a small, pager-like device that measures radiation dose rate. Its main purpose is to alert the wearer to the presence of radiation as quickly as possible. Detectors have very fast response times and include features such as water and dust resistance, intrinsic safety certifications, backlit displays, rugged cases, and resistance to electromagnetic and radio-frequency interference. They are designed for reliability in unknown environments. Most detectors use scintillation crystals to detect gamma or neutron radiation.

The main purpose of a dosimeter is to accurately measure the accumulated radiation dose that the wearer receives while wearing the device. The radiation sensor in a dosimeter is energy-compensated, which translates to a more accurate total dose measurement. Dosimeters come in many forms and use Geiger-Mueller tubes, silicon sensors or films to measure gamma, alpha, beta and neutron radiation doses. Most electronic personal dosimeters measure only gamma radiation because it's the most abundant and most likely type of radiation exposure.

Identifiers are instruments that use the differences in radiation emission energies to determine which radioisotope is present. Identifiers are mainly used to determine an unknown radioactive source or contamination. They are larger than both detectors and dosimeters and come in many form factors. Identifiers typically employ scintillation crystals (CsI or NaI) or semiconductors (CZT or germanium).

Survey meters measure radiation levels using the same radiation sensors employed in detectors and dosimeters. They have a probe that's held in one hand and a meter box held in the other. Each probe is specifically tailored to a particular type of radiation and can measure gamma, neutron, alpha or beta radiation levels.

Selecting the right equipment for your needs can be daunting with all of the available devices and options. Most people only need one or two types of devices that, when used properly, can make their jobs easier and safer. For first responders, response speed, ease of use, rugged design and portability often are as important as accuracy.

The following are suggestions for the type and minimum amounts of equipment needed to successfully detect radioisotopes:

• One personal radiation detector per person.
• One identifier per team (optional).
• One survey meter per team (optional).

Firefighters need fast-responding detectors to alert them to the presence of radioactive material. Each firefighter should wear a pager that is shock-, temperature- and water-resistant; intrinsically safe; and easy to operate while wearing gloves.

A survey meter should be used to determine safe distances from any sources and to ensure that responders have not been contaminated while performing their duties.

Hazmat responders need the most rugged and fastest responding radiation detectors possible to work in unknown hazardous environments. Important features for hazmat response include intrinsic safety; water-, shock- and EMI-resistance; ease of operation while wearing several layers of gloves; and illuminated, easy-to-read displays. Because hazmat responders may be exposed to more significant amounts of radiation, a detector-dosimeter combination instrument is ideal.

Each response team also should use an identifier to identify contamination and unknown sources. A survey meter should be used to determine safe distances from sources and to verify that no one has become contaminated while responding to the incident.

With this in mind, minimum equipment should include:

• One electronic personal dosimeter per person.
• One identifier per vehicle/team (optional).
• One survey meter per department (optional).

Emergency medical services personnel may be exposed to radiation if they are responding to an incident in which people have been contaminated with radioactive material. Because life-threatening conditions must be tended to before decontaminating a victim, EMS personnel may be exposed to radiation or contaminated. They need to be monitored using a dosimeter or a detector-dosimeter combination instrument to ensure they don't receive too high a dose.

Each EMS team or vehicle should use an identifier to determine what type of radioactive contamination is present so that both radioactive and toxic dangers can be identified. A survey meter should be used to ensure that the EMS response vehicle and personnel are not contaminated after an incident.