Bomb detector technology tops X-ray's
effectiveness
By Stephan Ohr
EE Times
(01/07/99, 5:35 p.m. EDT)
PEABODY, Mass. — Beyond crowded cabins, lost luggage and the
possibility of getting bumped even with confirmed reservations, the nagging
fear at the back of every air traveler's mind is sabotage. The X-ray
machines at today's airports can't find everything. Plastic explosives tucked
into a portable tape player are what brought down Pan Am Flight 103 over
Lockerbie, Scotland, 10 years ago.
"The FAA estimates that of the half-billion bags scanned each year, there
might be one — God forbid — with a bomb in it," said data-acquisition
guru Bernard M. Gordon, president of Analogic Systems, based here. The
company is about to roll out a bomb-detection system that makes clever
use of DSP technology to go beyond the capabilities of conventional
X-rays.
The eXaminer 3DX 6000 generates three-dimensional images of the
contents of airline luggage and carry-on bags. It takes a 360° X-ray, with
both high- and low-energy beams, calculates the relative density of objects
and materials, and then presents this information (with printouts) as a 3-D,
color-coded picture to a security-system operator. Thus, both metallic and
non-metallic bomb materials and triggers — ordinarily obscured by tape
cassette recorders, radios and other consumer gadgets — can be revealed.
In addition to explosives, the system can be used to detect drugs and other
illegal contraband.
Having won FAA approval for its system in November, Analogic says it is
ready to begin field trials this spring with selected airlines. The 3DX 6000,
put together under contract to Lockheed spinout L-3 Communications
(New York), is designed to scan 500 bags per hour. That's roughly one
every 6 seconds, Gordon confirmed — literally the equivalent of finding a
needle in a haystack.
The new entry — only the second computer-aided tomography (CT)
system to gain FAA certification for airport security — represents some of
the most sophisticated data-acquisition and DSP analysis available,
according to Analogic. (The other CT system to win the FAA's nod is from
InVision Technologies in San Jose, Calif. It uses embedded computers
from both Analogic and archrival Mercury Computer.)
"Conventional X-ray machines cannot reliably detect such bombs because
explosive material can be molded into various shapes and disguised as
commonly packed travel items which do not provoke the attention of the
X-ray operator. Such explosives also do not set off metal detectors," wrote
security-industry analyst Mark Hayes in a report crafted late last year for
Security 2001, an investment analysts' conference.
That's where the Analogic system steps up to bat. In operation, the scanner
circles an object 360°, capturing 24 helical slices, each 22 ms in duration.
(There are actually two slices captured in that interval: one high energy, the
other a lower-value radiation.) A total of 6,048 detectors — in 24 rows of
252 — pick up the energy penetrating the bag. This energy is amplified and
converted to digital format with 16-bit A/D converters sampling at 2
ksamples per second.
This generates roughly 12 million samples/s (6,000 channels x 2,000
samples per channel per second), said Gordon. At 16 bits per sample, that
means the data-acquisition system is generating a 200-Mbit/s data stream.
This stream travels to image-processing cards designed by Analogic's Sky
Computers subsidiary (Chelmsford, Mass.). Each of these cards — the
Shamrock models in the system approved by the FAA, and the newer
Excaliburs in the systems that will go into production — packs six Sharc
DSPs from Analog Devices Inc. and six custom DSPs. Each card
produces roughly 15 Gflops of DSP processing power. Two Sky pack
VME-based computers, each with four Excalibur cards, will be used in the
L-3 Communications bomb-detection system.
A single bag is actually scanned about 720 times in the six seconds it's
inside the 3DX 6000 examiner, according to Peter Harris, president of
International Security Systems Corp., a newly formed Analogic subsidiary.
The 100-kV X-ray probe rotates at 90 rpm around the bag.
The data capture must be fairly inclusive, even for the brief interval the bag
is in the scanner. But repeating the scans hundreds of times yields a fairly
revealing image. It would enable a trained operator to find, for example,
3.5 ounces of the plastic explosive Semtex hidden behind a radio.
Wake-up call
Though lengthy investigations have ruled out sabotage as the cause, it was
the explosion of TWA flight 800 over Long Island, N.Y. in July 1996 that
spurred demands for upgraded security, according to analyst Hayes. At the
time of the Lockerbie bombing in December 1988, he said, the FAA
standards were so stringent that no systems were able to meet them under
realistic airport operating conditions.
But the loss of Flight 800 was a wake-up call on the need for a coherent
plan for explosives detection. The White House Commission on Aviation
Safety and Security, headed by Vice President Al Gore, released a report
on the subject in September 1996. A month later Congress enacted
legislation that resulted in $144 million allocated for explosive-detection
systems and other advanced security equipment by air carriers and airport
authorities.
"Security in airports has become a more serious concern over the past
several years," a Mercury spokesman said. Since 1996, "there's been a
fairly impressive increase in the number of [detection] systems," he said.
With 20 InVision systems already operating, "The FAA purchased 67
explosives-detection systems from InVision last summer for installation [at
U.S. airline operations] in the United States, the U.K., France, Israel,
Japan, Malaysia, Saudi Arabia, Hong Kong, Taiwan, Belgium, the
Netherlands and the Philippines," he said.
And in July the FAA contracted for eight more systems, representing close
to $1 million in revenue for Mercury (Chelmsford, Mass.). "The technology
is similar to the MRI technology that both we and Analogic are deeply
involved in," the Mercury spokesman said.
According to Curt Disibio, chief financial officer of InVision, there was no
bomb-detection technology 10 years ago at the time of the Pan Am
disaster. But the shock waves from Lockerbie led "a number of companies
to initiate development to solve the problem. The collective industry — that
is, people trying to find bombs with technology — has gone from probably
$50 million three to four years ago to $150 million to $250 million today,
certified and noncertified," he said.
Market saturation is less than 5 percent, said Disibio, noting that the Gore
commission recommended spending $100 million a year for five years in
this area.
The size of the explosive- and substance-detection market depends on the
costs of the installed systems. They can run anywhere from $50,000 for a
retrofit of existing X-ray equipment to $600,000 for a high-end system,
said analyst Hayes. With 3,000 bomb-scanning systems in use around the
world — 1,400 of them in the United States — this represents a market
that could be as small as $250 million or as large as $1.8 billion.
However, most of the new CT systems for bomb scanning will cost in the
neighborhood of $200,000 to $250,000. "Several hundred thousand,"
conceded Harris of International Security Systems.
Analogic Corp. is listed in Security 2001 as major supplier to the
detection-equipment manufacturers, a group that includes American
Science & Engineering, Barringer Technologies, InVision, Magal Security
Systems, OSI Systems, Thermedics Detection and Vivid Technologies.
The two care-abouts in this industry, said Harris, are throughput and
minimization of false alarms. That forces a trade-off, he said, between
examining everything exhaustively and generating false alarms because of
ambiguous readings.
Analogic, along with its Sky subsidiary, manufactures CT, ultrasound and
magnetic resonance imaging systems for OEM customers. The $295 million
company possesses long-term expertise in data acquisition and DSP-based
imaging. |
