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Vehicles, containers, railway wagons
European Journal of Radiology 63 (2007) 254–262
Vehicles, containers, railway wagons H. Vogel ∗ Asklepios Klinik St. Georg, R¨ontgenabteilung, Lohm¨uhlenstrasse 5, 20099 Hamburg, Germany Received 3 March 2007; received in revised form 4 March 2007; accepted 5 March 2007
Abstract Purpose: Findings shall be shown which have been obtained employing X-rays, accelerator rays and gamma rays for control. Material and method: The observations have been made with transmission imaging, backscatter imaging, and with the combination of transmission with backscatter imaging. The images come from the manufacturers and from personal collections. Results: One has to look for the extra spaces room, which are often hidden and for the objects themselves. Conclusion: Weapons, explosive, cigarettes, drugs and other contraband can be found. The smugglers react to possible controls with X-rays. The controls of the future will combine different technologies. © 2007 Published by Elsevier Ireland Ltd. Keywords: Control with X-rays; Control of vehicles; Control of cars; Control of trucks; Control of containers
1. Introduction Vehicles, containers, and railway trains have large loading spaces. Those of an auto are smaller than those of a truck; this difference induces modifications in the controls. In these spaces goods can be hidden, it is even possible to use them for transport of nuclear bombs. The huge number of border crossing transports is a problem. The manufacturers of control technology name this a problem, which they promise to handle with their equipment. The findings of the search of vehicles, containers and railway wagons are described. 2. Material and method There are different technologies, which are employed like the following: • transmission imaging [1]; • backscatter imaging [2]; • combination of transmission with backscatter imaging. Radiation sources are (Fig. 2.1):
∗
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0720-048X/$ – see front matter © 2007 Published by Elsevier Ireland Ltd. doi:10.1016/j.ejrad.2007.03.041
• accelerators developed for vehicle search; • accelerators for radiotherapy modified to be employed in vehicle search; • radioactive elements like cobalt 60 and caesium 137 [10]; • conventional X-ray tubes. The equipment can be stationary or mobile. Radiotherapy accelerators modified for container search are used in Hamburg and in Rosenheim Bavaria [1,3]. Caesium 137 was used by the Stasi (Staatssicherheit, secret service of the former German Democratic Republic) for vehicle search at the inner German border [4,5,10]; cobalt 60 is employed for railway wagon search at the border Honduras Mexico; Cobalt 60 is employed in China for vehicle control [6]. 3. Results Vehicle search with X-rays is directed to: • • • • • • • •
spaces screened from view; spaces with own perfume (to cover detection by dogs); mimicry; unsuspicious spaces; extra spaces; spaces obscured by superpostition; spaces behind absorbing layers; special cases.
H. Vogel / European Journal of Radiology 63 (2007) 254–262
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Fig. 3.1.2. Drug parcels under the fender above the wheel. Backscatter image. AS&E, with friendly permission.
Fig. 2.1. Truck and container fluoroscopy (transmission imaging) in Hamburg. Two accelerators produce fan beams, vertical to each other. They hit a row of detectors. The truck with the container is drawn with constant speed through the fan beams. Transmission images are produced (similar to the scout view in CT).
Blinds are the door’s carpeting and the fender, which screens from view the space up to the wheel. A double carpet in the car boot or the car boot itself can serve as hiding place. In a truck and in a container, the loading space must be inspected passing via the door. Contraband hidden behind some meters of scrap has a good chance to avoid detection by inspection. The controlling officer has to force his way through a lot of dirt or scrap (Figs. 3.1.2–3.1.6). 3.2. Spaces with own perfume (to cover detection by dogs) Transporting drugs in vehicles, one has to avoid detection by inspection and by sniffing dogs. Therefore, the courier will combine hiding with coverage of odour. Sites that offer these two qualities are the gas tank and the oil sump (Fig. 3.2.1a–d). 3.3. Mimicry
Fig. 3.1.1. Drug packages under the driver’s seat. Transmission image. Spaces screened from view, not accessible for direct inspection.
3.1. Spaces screened from view There are spaces in each vehicle, which are part of the construction and which are not used for storage like the hollow space under the driver’s seat. Some of these spaces are not easy accessible for inspection (Fig. 3.1.1).
Preparing for control with X-rays, the drug couriers can give the drug parcels the form of surrounding goods (mimicry). The adaptation is demanding and the effort has to have a reasonable relation to the possible profit. Mimicry concerns drugs which can be packed in parcels like those of the shipped goods (Fig. 3.3.1). If mimicry is suspected, one has to look for slight differences in form and size; this is valid for transmission and backscatter imaging (Fig. 3.3.2). A load of multiple parcels may raise suspicion. The origin country and the destination of the shipping may raise suspicion too.
Fig. 3.1.3. Dug parcels under the front fender above the front wheel and in the carpeting. Explosives in the gear. Backscatter images.
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3.6. Superposition and distracted attention.
Fig. 3.1.4. Multiple parcels (explosives and others), hidden at different sites. Fertilizer in the trunk. Backscatter image. AS&E, with friendly permission.
More difficult is the detection of stolen cars, when they are disassembled into parts, which are hidden under scrap (Fig. 3.3.3). 3.4. Unsuspicious spaces
Superposition by metal can be used to prevent detection by transmission and backscatter imaging: in Hamburg, an old-timer car passed the customs in a container; it came from Argentina. The petrol tank and the oil sump were empty (Fig. 3.6.1a); the transmission image in horizontal projection was inconclusive. In vertical projection, however, parcels could be seen, which were hidden in the ceiling’s carpeting (Fig. 3.6.1b and c). Superposition of the truck’s back axle made the recognition difficult. In Hamburg, the newspapers reported a similar case, which illustrates the option to prevent detection by distracting the attention: the customs had discovered drugs in an old-timer car; the car was confiscated. The prosecution of the drug dealers being finished, the car was sold by auction. An amateur bought it; fixing it up, he found parcels in the rear trunk’s carpeting. The customs had been content to discover something; the most essential remained undetected due to the first discovery. 3.7. Goods behind absorbing layers.
Spaces, which are unknown, or, whose contents are thought to be unknown to the searching team, are used to hide contraband, even if X-ray control is expected. An example is the refrigerator’s room (Fig. 3.4.1), the hollow space in the container’s double wall (Fig. 3.4.2a) and the reserve wheel (Fig. 3.4.2b).
The manufacturers advertise their products with indicating their efficiency; they indicate that their technology allows detecting items behind metal, in extremis, in a safe with thick walls (Fig. 3.7.1). Increasing the radiation’s energy or/and prolonging the exposure leads to readable images; a further improvement can be obtained by image editing (Figs. 3.7.2 and 3.7.3).
3.5. Extra rooms 3.8. Railway wagons, airports Rooms, created to transport contraband, are often difficult to access and/or hidden behind dividing walls or other rooms filled with goods (Fig. 3.5.1).
A railway wagon is X-rayed with cobalt 60 (Fig. 3.8.1); a transmission image is obtained. The investigation is time con-
Fig. 3.1.5. Cigarettes behind scrap – difficult to inspect. Transmission image.
Fig. 3.1.6. Barrels with alcohol, which was not in the transport declaration. They are hidden behind several mattresses. Transmission image.
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Fig. 3.2.1. Old-timer car, reimported from Argentina to Germany after decades. The overview (a) shows the two old-timer cars in the container. The enlarged section of the second car (b) shows that the gas tank is not empty. Sections of the oil sump and the gas tank (c and d) show parcels; they are too large for cigarette parcels. The hiding place with its proper odour and the place or origin (South America) indicates drugs. Transmission image with 10 MeV produced with accelerators.
suming. The dimensions limit the resolution. The necessary exposure is obtained, when the train slowly passes through the fan beam. Another possibility is the examination with backscatter imaging. A ship, an airplane and a helicopter can be examined too; transmission imaging, however is hardly possible because the investigated object has to be placed between the radiation source and the detector. Backscatter imaging is an alternative, because
detector and radiation source are together at one side of the object. This offers advantages for the control of goods shipped and transported with planes (Fig. 3.8.2). 3.9. Transmission and backscatter imaging Transmission imaging needs the radiation source on the side of the investigated object opposite to the detector. Backscatter
Fig. 3.3.1. Drug parcels in form of lemons in a container with a load of lemons. Comparing the load’s parcels, the three rows in the middle show a slight difference in form, size and absorption. The custom in Hamburg followed the container and identified a group of drug merchants. The expeditor probably expected the control with X-rays and tried to avoid detection by mimicry (imitation of form, size and absorption of the surrounding’s objects. Transmission imaging with accelerators.
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Fig. 3.3.2. Drug parcels hidden among similar parcels. Transmission imaging (left) and backscatter imaging (right). The backscatter image shows the drug parcels (circle) and the surrounding parcels. The transmission image hardly allows differentiating. AS&E, with friendly permission.
4. Discussion Vehicle search will develop. The future will employ new methods with new tools, like pattern recognition and stepwise approach. Search of vehicles will play its part in preventing terrorist attacks with explosive devices of important dimensions and proliferation of arms. 4.1. Present
Fig. 3.3.3. Stolen cars, disassembled into parts, hidden under scrap. Transmission imaging.
imaging has the advantage that this is not necessary, detector and radiation source have to be on the same side; they can be installed in a car (Figs. 3.9.1 and 3.9.2). Backscatter imaging visualizes items near the tube. The opposite side has to be examined by a second scan. The transmission image shows everything in superposition; backscatter imaging only a part, backscatter images have therefore some similarity with photos (Fig. 3.9.3).
Today millions and millions of goods are transported in containers, trucks and railway wagons. Few of them are inspected; even fewer are searched with X-rays. The controls are sporadic. The control units are stationary or mobile [1,2,5–7]. The producers advertise their equipment, insisting that controls can be performed in seconds at any place at any time with little manpower. Radiation is produced with accelerators, cobalt 60 or caesium 137; accelerators are faster than those with radioactive substances. Transmission images are produced with fan beams or pencil beams, backscatter images with pencil beams. There are technologies combining transmission and backscatter imaging. Backscatter imaging uses the scatter radiation coming from the surface of an object. The images are similar to photos, they show details which are difficult to recognize on transmission images due to disturbing superposition; however,
Fig. 3.4.1. Cigarette packages around the refrigerating aggregate in the container’s front wall. Overview and enlarged section. Transmission imaging with accelerators.
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Fig. 3.4.2. Cigarettes in the container’s double wall; parcels in red (a). The limit to the empty space is above the back wheel. Cigarettes in the reserve wheel (b). Transmission imaging with accelerators.
Fig. 3.5.1. Extra room filled with cocaine parcels between the back wall of the driver’s cabin and the front wall of the loading room. Backscatter image. AS&E, with friendly permission.
objects at the side of the container opposite to the observer are not visualized. 4.2. Future In the future new tasks and new technologies will meet each other. A terrorist attack with an explosive device hidden in a
Fig. 3.7.1. Test image to demonstrate the possibilities of the equipment. Bicycle spokes can be seen (arrow), Behind 12 cm of steel a detail is visualized (arrow. “Shaped energy”, combination of transmission and backscatter imaging). AS&E, with friendly permission.
container could be the trigger. The device could be conventional or nuclear; it could be combined with radioactive material (dirty bomb), bacteria (B-weapon) or toxic gas (C-weapons). The manufacturers describe this scenario. If the attack gets the attention of the media (and the public) this would mean a boost for search technologies with X-rays.
Fig. 3.6.1. a–c Old-timer car, imported from South America. The petrol tank is empty. In the vertical projection the car is superimposed by the truck’s back axles (b). Detailed analysis reveals parcels (c); they were found in the ceiling’s carpeting. Transmission imaging.
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Fig. 3.7.2. Differences of resolution of contrast and details. Truck with a load. The transmission image with ordinary values visualizes the barrels filled with liquids; they become transparent and hidden items become visible.
4.3. Algorithms
Fig. 3.7.3. Tank truck. In the load parcels are visualized (circles). Transmission imaging. AS&E, with friendly permission.
There would be new demands towards the existing technologies, which would induce new concepts. Search of large vehicles performed in seconds would be among them; this would be too much for a human before a screen, computerized analysis of the images will be developed.
Some specifications of future pattern recognition software can be predicted. Spaces normally empty would be checked of being empty. The petrol tank and the oil pit would be checked of being empty, and of containing liquid or parcels (drugs). Goods in large numbers would be checked for differences of size, form, absorption - an example is the own observation of drug parcels in the form of lemons. Scrap could be searched for parts of stolen cars. Extra rooms would raise suspicion; this will be valid too for rooms lacking insight due to superposition or to absorbing layers. The object will be analyzed. The search will concern the: • • • •
form of a parcel, weapon or bottle with spirit; nature (liquid, recognized by waves); animals living or dead or parts of (protected animals); objects which are forbidden to be transported;
Fig. 3.8.1. Car transport, grain hopper, covered gondola, b: train transmission imaging with cobalt 60. SAIC, with friendly permission.
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Fig. 3.8.2. Goods to be transported by plane. Backscatter image. AS&E, with friendly permission.
4.4. Stepwise analysis/prosecution
Fig. 3.9.1. Transmission imaging. Mobile unit. Truck with extension arm for the detector. AS&E, with friendly permission.
• • • •
explosive devices; arms; rockets or parts of rockets; nuclear arms, part of nuclear arms, equipment of nuclear technology.
Normal controls have to be differentiated from objectorientated search. Normal controls are meant as prophylaxis; illegal transports shall not occur (because they will be detected). This will be different, if a nuclear explosive device is searched; the same could be valid for rockets against passenger airplanes and their parts. Normal control must not disturb the ordinary traffic. A nuclear danger will be different. A normal control ought not to be expensive. Therefore, a stepwise proceeding will be practised. If the first image allows to identify everything or to exclude anything forbidden, the control can be finished; if not inspection and/or a second search with X-ray (producing and image in a different projection) may follow, spectroscopy to identify substances without taking hand of them could be used. 4.5. Laws/distracted attention
The computer may have advantages because a human could have more difficulties identifying something, which he/she had never seen before. On the contrary, self-learning (improving) software will be part of the search technology.
Those who transport react to the search with X-rays. Their own observations are one proof (drug parcels in form of lemons, stolen cars put into parts hidden under scrap). They will use whatever they can to avoid detection; that can be lawless. In Germany, it is forbidden to irradiate food, which is done elsewhere to kill bacteria for conservation; therefore loads with food will not be searched with X-rays [8,9]. Probably psychology will be employed too. The officers having discovered something could
Fig. 3.9.2. Transmission imaging combined with backscatter imaging. AS&E, with friendly permission.
Fig. 3.9.3. Transmission (above) and backscatter imaging (below). On the transmission image the goods can hardly be recognized, superposition limits the identification. The backscatter image shows the goods; there is no superposition. The visualized layer is near the observer. AS&E, with friendly permission.
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be tempted not to look for something else; the consequence would be to offer something small for passing something of value. References [1] Lotz P. Durchleuchtung an Grenzen. Die Containerdurchleuchtungsanlage am Hamburger Hafen. Hamburg: Diss; 2002. [2] Rothschild PJ. Backscatter techniques – an alternative to body search. In: EU (2003), radiation protection Nr. 130 – medico-legal exposures with ionising radiation without medical indication. Proceedings of the international symposium. 2002. p. 31–8 (ISBN 92-894-6890-4). [3] Roos G. Ministerium f¨ur Umwel Forsten und Verbraucherschutz. Mainz: Oral communication; 2003. [4] Halter H.Es gibt kein Entrinnen – u¨ ber die radioaktiven Grenzkrontrollen der DDR, 51. Spiegel; 1994. p. 176. [5] Eisenfeld, et al. Einsatz von R¨ontgenstrahler und radioaktiven Stoffen durch das Ministerium f¨ur Staatssicherheit gegen Oppositionelle – Fiktion der Realit¨at? Berlin: Projektgruppe Strahlen; 2000.
[6] Magnusson T. The role of X-rays in drug detection. In: EU (2003), radiation protection Nr. 130 – medico-legal exposures with ionising, radiation without medical indication. Proceedings of the international symposium. 2002. p. 56–8. [7] Detection of weapons. In: EU (2003) radiation protection Nr. 130 – medico-legal exposures with ionising radiation without medical indication. Proceedings of the international symposium. 2002. p. 48–55 (ISBN 92-894-6890-4). [8] EU. Radiation protection. In: EU (2003), Nr. 130 – medico-legal exposures with ionising radiation without medical indication. Proceedings of the international symposium. 2003. p. 39–40 (ISBN 92-894-6890-4). [9] Rogers K. The use of transmission- based technology in the detection of, clandestine entrants. In: EU (2003), radiation protection Nr. 130 – medico-legal exposures with ionising, radiation without medical indication. Proceedings of the international symposium. 2002. p. 39–40 (ISBN 92-84-6890-4). [10] Strahlenschutzkommission. Stellungnahme der Strahlenschutzkommission: Strahlenrisiko durch ehemalige DDR-Grenzkontrollen mittels Cs-137-Strahlung. Ver¨offentlichungen der Strahlenschutzkommission, Bad. 39; 1995 (Verabschiedet in der 129. Sitzung am 17.02.1995).
Vehicles, containers, railway wagons H. Vogel ∗ Asklepios Klinik St. Georg, R¨ontgenabteilung, Lohm¨uhlenstrasse 5, 20099 Hamburg, Germany Received 3 March 2007; received in revised form 4 March 2007; accepted 5 March 2007
Abstract Purpose: Findings shall be shown which have been obtained employing X-rays, accelerator rays and gamma rays for control. Material and method: The observations have been made with transmission imaging, backscatter imaging, and with the combination of transmission with backscatter imaging. The images come from the manufacturers and from personal collections. Results: One has to look for the extra spaces room, which are often hidden and for the objects themselves. Conclusion: Weapons, explosive, cigarettes, drugs and other contraband can be found. The smugglers react to possible controls with X-rays. The controls of the future will combine different technologies. © 2007 Published by Elsevier Ireland Ltd. Keywords: Control with X-rays; Control of vehicles; Control of cars; Control of trucks; Control of containers
1. Introduction Vehicles, containers, and railway trains have large loading spaces. Those of an auto are smaller than those of a truck; this difference induces modifications in the controls. In these spaces goods can be hidden, it is even possible to use them for transport of nuclear bombs. The huge number of border crossing transports is a problem. The manufacturers of control technology name this a problem, which they promise to handle with their equipment. The findings of the search of vehicles, containers and railway wagons are described. 2. Material and method There are different technologies, which are employed like the following: • transmission imaging [1]; • backscatter imaging [2]; • combination of transmission with backscatter imaging. Radiation sources are (Fig. 2.1):
∗
Tel.: +49 40 181885 2318; fax: +49 40 181885 4192. E-mail address: [email protected].
0720-048X/$ – see front matter © 2007 Published by Elsevier Ireland Ltd. doi:10.1016/j.ejrad.2007.03.041
• accelerators developed for vehicle search; • accelerators for radiotherapy modified to be employed in vehicle search; • radioactive elements like cobalt 60 and caesium 137 [10]; • conventional X-ray tubes. The equipment can be stationary or mobile. Radiotherapy accelerators modified for container search are used in Hamburg and in Rosenheim Bavaria [1,3]. Caesium 137 was used by the Stasi (Staatssicherheit, secret service of the former German Democratic Republic) for vehicle search at the inner German border [4,5,10]; cobalt 60 is employed for railway wagon search at the border Honduras Mexico; Cobalt 60 is employed in China for vehicle control [6]. 3. Results Vehicle search with X-rays is directed to: • • • • • • • •
spaces screened from view; spaces with own perfume (to cover detection by dogs); mimicry; unsuspicious spaces; extra spaces; spaces obscured by superpostition; spaces behind absorbing layers; special cases.
H. Vogel / European Journal of Radiology 63 (2007) 254–262
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Fig. 3.1.2. Drug parcels under the fender above the wheel. Backscatter image. AS&E, with friendly permission.
Fig. 2.1. Truck and container fluoroscopy (transmission imaging) in Hamburg. Two accelerators produce fan beams, vertical to each other. They hit a row of detectors. The truck with the container is drawn with constant speed through the fan beams. Transmission images are produced (similar to the scout view in CT).
Blinds are the door’s carpeting and the fender, which screens from view the space up to the wheel. A double carpet in the car boot or the car boot itself can serve as hiding place. In a truck and in a container, the loading space must be inspected passing via the door. Contraband hidden behind some meters of scrap has a good chance to avoid detection by inspection. The controlling officer has to force his way through a lot of dirt or scrap (Figs. 3.1.2–3.1.6). 3.2. Spaces with own perfume (to cover detection by dogs) Transporting drugs in vehicles, one has to avoid detection by inspection and by sniffing dogs. Therefore, the courier will combine hiding with coverage of odour. Sites that offer these two qualities are the gas tank and the oil sump (Fig. 3.2.1a–d). 3.3. Mimicry
Fig. 3.1.1. Drug packages under the driver’s seat. Transmission image. Spaces screened from view, not accessible for direct inspection.
3.1. Spaces screened from view There are spaces in each vehicle, which are part of the construction and which are not used for storage like the hollow space under the driver’s seat. Some of these spaces are not easy accessible for inspection (Fig. 3.1.1).
Preparing for control with X-rays, the drug couriers can give the drug parcels the form of surrounding goods (mimicry). The adaptation is demanding and the effort has to have a reasonable relation to the possible profit. Mimicry concerns drugs which can be packed in parcels like those of the shipped goods (Fig. 3.3.1). If mimicry is suspected, one has to look for slight differences in form and size; this is valid for transmission and backscatter imaging (Fig. 3.3.2). A load of multiple parcels may raise suspicion. The origin country and the destination of the shipping may raise suspicion too.
Fig. 3.1.3. Dug parcels under the front fender above the front wheel and in the carpeting. Explosives in the gear. Backscatter images.
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3.6. Superposition and distracted attention.
Fig. 3.1.4. Multiple parcels (explosives and others), hidden at different sites. Fertilizer in the trunk. Backscatter image. AS&E, with friendly permission.
More difficult is the detection of stolen cars, when they are disassembled into parts, which are hidden under scrap (Fig. 3.3.3). 3.4. Unsuspicious spaces
Superposition by metal can be used to prevent detection by transmission and backscatter imaging: in Hamburg, an old-timer car passed the customs in a container; it came from Argentina. The petrol tank and the oil sump were empty (Fig. 3.6.1a); the transmission image in horizontal projection was inconclusive. In vertical projection, however, parcels could be seen, which were hidden in the ceiling’s carpeting (Fig. 3.6.1b and c). Superposition of the truck’s back axle made the recognition difficult. In Hamburg, the newspapers reported a similar case, which illustrates the option to prevent detection by distracting the attention: the customs had discovered drugs in an old-timer car; the car was confiscated. The prosecution of the drug dealers being finished, the car was sold by auction. An amateur bought it; fixing it up, he found parcels in the rear trunk’s carpeting. The customs had been content to discover something; the most essential remained undetected due to the first discovery. 3.7. Goods behind absorbing layers.
Spaces, which are unknown, or, whose contents are thought to be unknown to the searching team, are used to hide contraband, even if X-ray control is expected. An example is the refrigerator’s room (Fig. 3.4.1), the hollow space in the container’s double wall (Fig. 3.4.2a) and the reserve wheel (Fig. 3.4.2b).
The manufacturers advertise their products with indicating their efficiency; they indicate that their technology allows detecting items behind metal, in extremis, in a safe with thick walls (Fig. 3.7.1). Increasing the radiation’s energy or/and prolonging the exposure leads to readable images; a further improvement can be obtained by image editing (Figs. 3.7.2 and 3.7.3).
3.5. Extra rooms 3.8. Railway wagons, airports Rooms, created to transport contraband, are often difficult to access and/or hidden behind dividing walls or other rooms filled with goods (Fig. 3.5.1).
A railway wagon is X-rayed with cobalt 60 (Fig. 3.8.1); a transmission image is obtained. The investigation is time con-
Fig. 3.1.5. Cigarettes behind scrap – difficult to inspect. Transmission image.
Fig. 3.1.6. Barrels with alcohol, which was not in the transport declaration. They are hidden behind several mattresses. Transmission image.
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Fig. 3.2.1. Old-timer car, reimported from Argentina to Germany after decades. The overview (a) shows the two old-timer cars in the container. The enlarged section of the second car (b) shows that the gas tank is not empty. Sections of the oil sump and the gas tank (c and d) show parcels; they are too large for cigarette parcels. The hiding place with its proper odour and the place or origin (South America) indicates drugs. Transmission image with 10 MeV produced with accelerators.
suming. The dimensions limit the resolution. The necessary exposure is obtained, when the train slowly passes through the fan beam. Another possibility is the examination with backscatter imaging. A ship, an airplane and a helicopter can be examined too; transmission imaging, however is hardly possible because the investigated object has to be placed between the radiation source and the detector. Backscatter imaging is an alternative, because
detector and radiation source are together at one side of the object. This offers advantages for the control of goods shipped and transported with planes (Fig. 3.8.2). 3.9. Transmission and backscatter imaging Transmission imaging needs the radiation source on the side of the investigated object opposite to the detector. Backscatter
Fig. 3.3.1. Drug parcels in form of lemons in a container with a load of lemons. Comparing the load’s parcels, the three rows in the middle show a slight difference in form, size and absorption. The custom in Hamburg followed the container and identified a group of drug merchants. The expeditor probably expected the control with X-rays and tried to avoid detection by mimicry (imitation of form, size and absorption of the surrounding’s objects. Transmission imaging with accelerators.
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Fig. 3.3.2. Drug parcels hidden among similar parcels. Transmission imaging (left) and backscatter imaging (right). The backscatter image shows the drug parcels (circle) and the surrounding parcels. The transmission image hardly allows differentiating. AS&E, with friendly permission.
4. Discussion Vehicle search will develop. The future will employ new methods with new tools, like pattern recognition and stepwise approach. Search of vehicles will play its part in preventing terrorist attacks with explosive devices of important dimensions and proliferation of arms. 4.1. Present
Fig. 3.3.3. Stolen cars, disassembled into parts, hidden under scrap. Transmission imaging.
imaging has the advantage that this is not necessary, detector and radiation source have to be on the same side; they can be installed in a car (Figs. 3.9.1 and 3.9.2). Backscatter imaging visualizes items near the tube. The opposite side has to be examined by a second scan. The transmission image shows everything in superposition; backscatter imaging only a part, backscatter images have therefore some similarity with photos (Fig. 3.9.3).
Today millions and millions of goods are transported in containers, trucks and railway wagons. Few of them are inspected; even fewer are searched with X-rays. The controls are sporadic. The control units are stationary or mobile [1,2,5–7]. The producers advertise their equipment, insisting that controls can be performed in seconds at any place at any time with little manpower. Radiation is produced with accelerators, cobalt 60 or caesium 137; accelerators are faster than those with radioactive substances. Transmission images are produced with fan beams or pencil beams, backscatter images with pencil beams. There are technologies combining transmission and backscatter imaging. Backscatter imaging uses the scatter radiation coming from the surface of an object. The images are similar to photos, they show details which are difficult to recognize on transmission images due to disturbing superposition; however,
Fig. 3.4.1. Cigarette packages around the refrigerating aggregate in the container’s front wall. Overview and enlarged section. Transmission imaging with accelerators.
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Fig. 3.4.2. Cigarettes in the container’s double wall; parcels in red (a). The limit to the empty space is above the back wheel. Cigarettes in the reserve wheel (b). Transmission imaging with accelerators.
Fig. 3.5.1. Extra room filled with cocaine parcels between the back wall of the driver’s cabin and the front wall of the loading room. Backscatter image. AS&E, with friendly permission.
objects at the side of the container opposite to the observer are not visualized. 4.2. Future In the future new tasks and new technologies will meet each other. A terrorist attack with an explosive device hidden in a
Fig. 3.7.1. Test image to demonstrate the possibilities of the equipment. Bicycle spokes can be seen (arrow), Behind 12 cm of steel a detail is visualized (arrow. “Shaped energy”, combination of transmission and backscatter imaging). AS&E, with friendly permission.
container could be the trigger. The device could be conventional or nuclear; it could be combined with radioactive material (dirty bomb), bacteria (B-weapon) or toxic gas (C-weapons). The manufacturers describe this scenario. If the attack gets the attention of the media (and the public) this would mean a boost for search technologies with X-rays.
Fig. 3.6.1. a–c Old-timer car, imported from South America. The petrol tank is empty. In the vertical projection the car is superimposed by the truck’s back axles (b). Detailed analysis reveals parcels (c); they were found in the ceiling’s carpeting. Transmission imaging.
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Fig. 3.7.2. Differences of resolution of contrast and details. Truck with a load. The transmission image with ordinary values visualizes the barrels filled with liquids; they become transparent and hidden items become visible.
4.3. Algorithms
Fig. 3.7.3. Tank truck. In the load parcels are visualized (circles). Transmission imaging. AS&E, with friendly permission.
There would be new demands towards the existing technologies, which would induce new concepts. Search of large vehicles performed in seconds would be among them; this would be too much for a human before a screen, computerized analysis of the images will be developed.
Some specifications of future pattern recognition software can be predicted. Spaces normally empty would be checked of being empty. The petrol tank and the oil pit would be checked of being empty, and of containing liquid or parcels (drugs). Goods in large numbers would be checked for differences of size, form, absorption - an example is the own observation of drug parcels in the form of lemons. Scrap could be searched for parts of stolen cars. Extra rooms would raise suspicion; this will be valid too for rooms lacking insight due to superposition or to absorbing layers. The object will be analyzed. The search will concern the: • • • •
form of a parcel, weapon or bottle with spirit; nature (liquid, recognized by waves); animals living or dead or parts of (protected animals); objects which are forbidden to be transported;
Fig. 3.8.1. Car transport, grain hopper, covered gondola, b: train transmission imaging with cobalt 60. SAIC, with friendly permission.
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Fig. 3.8.2. Goods to be transported by plane. Backscatter image. AS&E, with friendly permission.
4.4. Stepwise analysis/prosecution
Fig. 3.9.1. Transmission imaging. Mobile unit. Truck with extension arm for the detector. AS&E, with friendly permission.
• • • •
explosive devices; arms; rockets or parts of rockets; nuclear arms, part of nuclear arms, equipment of nuclear technology.
Normal controls have to be differentiated from objectorientated search. Normal controls are meant as prophylaxis; illegal transports shall not occur (because they will be detected). This will be different, if a nuclear explosive device is searched; the same could be valid for rockets against passenger airplanes and their parts. Normal control must not disturb the ordinary traffic. A nuclear danger will be different. A normal control ought not to be expensive. Therefore, a stepwise proceeding will be practised. If the first image allows to identify everything or to exclude anything forbidden, the control can be finished; if not inspection and/or a second search with X-ray (producing and image in a different projection) may follow, spectroscopy to identify substances without taking hand of them could be used. 4.5. Laws/distracted attention
The computer may have advantages because a human could have more difficulties identifying something, which he/she had never seen before. On the contrary, self-learning (improving) software will be part of the search technology.
Those who transport react to the search with X-rays. Their own observations are one proof (drug parcels in form of lemons, stolen cars put into parts hidden under scrap). They will use whatever they can to avoid detection; that can be lawless. In Germany, it is forbidden to irradiate food, which is done elsewhere to kill bacteria for conservation; therefore loads with food will not be searched with X-rays [8,9]. Probably psychology will be employed too. The officers having discovered something could
Fig. 3.9.2. Transmission imaging combined with backscatter imaging. AS&E, with friendly permission.
Fig. 3.9.3. Transmission (above) and backscatter imaging (below). On the transmission image the goods can hardly be recognized, superposition limits the identification. The backscatter image shows the goods; there is no superposition. The visualized layer is near the observer. AS&E, with friendly permission.
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be tempted not to look for something else; the consequence would be to offer something small for passing something of value. References [1] Lotz P. Durchleuchtung an Grenzen. Die Containerdurchleuchtungsanlage am Hamburger Hafen. Hamburg: Diss; 2002. [2] Rothschild PJ. Backscatter techniques – an alternative to body search. In: EU (2003), radiation protection Nr. 130 – medico-legal exposures with ionising radiation without medical indication. Proceedings of the international symposium. 2002. p. 31–8 (ISBN 92-894-6890-4). [3] Roos G. Ministerium f¨ur Umwel Forsten und Verbraucherschutz. Mainz: Oral communication; 2003. [4] Halter H.Es gibt kein Entrinnen – u¨ ber die radioaktiven Grenzkrontrollen der DDR, 51. Spiegel; 1994. p. 176. [5] Eisenfeld, et al. Einsatz von R¨ontgenstrahler und radioaktiven Stoffen durch das Ministerium f¨ur Staatssicherheit gegen Oppositionelle – Fiktion der Realit¨at? Berlin: Projektgruppe Strahlen; 2000.
[6] Magnusson T. The role of X-rays in drug detection. In: EU (2003), radiation protection Nr. 130 – medico-legal exposures with ionising, radiation without medical indication. Proceedings of the international symposium. 2002. p. 56–8. [7] Detection of weapons. In: EU (2003) radiation protection Nr. 130 – medico-legal exposures with ionising radiation without medical indication. Proceedings of the international symposium. 2002. p. 48–55 (ISBN 92-894-6890-4). [8] EU. Radiation protection. In: EU (2003), Nr. 130 – medico-legal exposures with ionising radiation without medical indication. Proceedings of the international symposium. 2003. p. 39–40 (ISBN 92-894-6890-4). [9] Rogers K. The use of transmission- based technology in the detection of, clandestine entrants. In: EU (2003), radiation protection Nr. 130 – medico-legal exposures with ionising, radiation without medical indication. Proceedings of the international symposium. 2002. p. 39–40 (ISBN 92-84-6890-4). [10] Strahlenschutzkommission. Stellungnahme der Strahlenschutzkommission: Strahlenrisiko durch ehemalige DDR-Grenzkontrollen mittels Cs-137-Strahlung. Ver¨offentlichungen der Strahlenschutzkommission, Bad. 39; 1995 (Verabschiedet in der 129. Sitzung am 17.02.1995).