Corrections Facility SecurityMove over, Superman

Jan 1, 1999 12:00 PM, Steven W. Smith

Security scanner uses x-ray vision to detect concealed drugs and weapons.Security managers used to have only two options for detecting contraband and weapons concealed under clothing: metal detectors and pat-down searches. X-rays were not used for personnel screening because safety experts and security managers agreed the required radiation exposure was unsafe. A technological break-through from the early 1990s - "back-scatter imaging" - now allows people to be screened with negligible radiation levels.

More than two dozen such systems are currently in use in the United States, with additional systems in Mexico, Argentina and the Middle East. About half of them are used by the California Department of Corrections to screen prison visitors. The U.S. Customs Department recently purchased a system for field trials at an international airport on the East Coast. The x-ray device, called the Secure 1000, is manufactured by Rapiscan Security Products, Hawthorne, Calif., which sells about 30 percent of airport baggage scanners worldwide.

How it worksAbout the size of a kitchen refrigerator, the x-ray body scanner screens people from a distance of 8 inches as they stand motionless for three seconds. A computer-enhanced image of the person's outline and any concealed objects then appears on a monitor. Each three-second scan produces an image of one side of the body. Multiple views, such as front, rear and sides, require people to turn their bodies for additional scans. The monitor is usually in an adjacent room to prevent perpetrators from learning how the system works and to protect people from invasion of privacy.

Unlike medical x-rays that pass through the body, the scanner's x-rays penetrate only a half-inch below the body surface with a narrow beam of low-energy radiation. The scanner then detects the portion that is back-scattered (reflected) and displays that image on the monitor. For instance, the scanner can detect shin bones but not the ribs and internal organs. For cases in which people wear heavy clothing, the system can locate items in pockets, hidden in seams or concealed in clothing. Metal objects appear blue or black in the image, while organic material, such as drugs and explosives, are white or yellow.The system is easy to use. Users need less than an hour of formal instruction to operate the device, followed by several hours of on-the-job training to gain experience in understanding the images.

The x-ray device weighs about 600 pounds and is on casters for mobility. Small enough to fit through standard doorways, the scanner plugs into a standard electrical outlet. Setup usually requires less than two hours.Detection CapabilitiesThe scanner detects both metallic and nonmetallic objects. More sensitive than conventional walk-through metal detectors, it often detects metal objects weighing less than one gram. In a prison or jail, it could find hidden razor blades, handcuff keys or bullets. It can detect metal in unusual forms, such as powders and slurries. "Conventional metal detectors cannot locate these special forms of gold, silver and platinum," says Phil Wascher, vice president of marketing. "The precious metal industry is very interested in the Secure 1000 to reduce employee theft."

Detecting nonmetallic objects hidden under clothing has always been a problem for security, including contraband such as drugs, currency and documents, as well as weapons and explosives used by terrorists. How small a quantity of drugs can the device detect? Wascher says, "For obvious reasons, we don't publicly discuss the minimum detectable quantities."However, the quantity of drugs involved in prison smuggling is typically a few grams, he says. A California prison has made some 27 drug arrests by using the scanner in its visitor reception center. In anti-terrorist activities, the scanner can detect a half pound of plastic explosives, the amount officials believe was used to destroy Pan Am Flight 103 in 1988 as it was flying over Lockerbie, Scotland. A range of other nonmetallic objects also can be detected, from wooden clubs and bone knifes, to guns made of high-tech plastics and ceramics.

Twelve systems have been installed in California prisons in the last 18 months, and an additional six systems have been ordered. "We liked what we found," says Larry Cothran, executive officer of the Technology Transfer Committee. "Introduction of the body scanner into our visitor centers has dramatically reduced the amount of contraband brought in by visitors." While weapons and prohibited items (such as currency) are always important in prison visitor screening, a key focus is on the detection of illicit drugs. We have seen a 70-percent reduction in drug-related offenses inside."

Is It Safe?Each scan produces 3 microRem of radiation. For comparison, medical x-rays typically expose patients to 30,000-300,000 microRem per examination. All people receive about 300 microRem each day from naturally occurring radioactive materials in the air and soil, plus additional exposure from common daily activities, according to Rapiscan officials. For instance, Denver residents get about 600 microRem each day because they live at a high elevation in the Rocky Mountains, and passengers on commercial airliners receive about 500 microRem each hour of flight.

The safety extends to special groups, such as children, pregnant women and people who wear pacemakers, the company says.Some radiation safety experts maintain that x-ray imaging should be restricted to medical applications, regardless of the radiation level. In addition, some states have laws restricting the nonmedical use of x-rays. However, these laws were written at a time when radiation exposures needed to be thousands of times greater. To date, none of the laws have prevented the x-ray body scanner from being used.

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