- Email: [email protected]
Search for persons
European Journal of Radiology 63 (2007) 220–226
Search for persons H. Vogel ∗ Asklepios Klinik St. Georg, Radiology, Lohm¨uhlenstr. 5 20099 Hamburg, Germany Received 3 March 2007; received in revised form 4 March 2007; accepted 5 March 2007
Abstract X-rays and gamma-rays are used to detect hidden persons in vehicles, containers, and railway wagons. They are produced with accelerators, X-ray tubes, cobalt 60 and caesium 137. Fan beams adjusted to a line of digital detectors produce the image. The resolution is sufficient to recognise a human being. The recognition of persons with transmission images is limited by superimposition; backscatter imaging produces clearer images but of one single layer only. The future will bring new applications of search for persons with X-rays. Crimes and terrorist attacks will induce added demand for security, where search with X-rays and gamma-rays will keep its important role or even increase it. © 2007 Published by Elsevier Ireland Ltd. Keywords: Search for persons; Transmission imaging; Backscatter imaging; Imaging with cobalt 60; Imaging with caesium 137
1. Introduction The search for humans serves two goals: detection and protection. Illegal aliens shall be detected and stow-aways shall not perish in their hiding place [1]. Tragedies have become known when citizens of the communist German democratic republic were detected, when fleeing to the west. Some of them were discovered by control units, which produced transmission images of trucks and cars with gamma-rays help of caesium 137 [2,3]. Border controls with gamma- or X-rays are quite common; they have been practised in North America, at the Chunnel between Calais and Dover (when France placed the camp for asylum seekers directly beside the railways to England), in Germany a prison in Hesse tried to implement laundry control with X-rays, because detainees used the laundry boxes for escape [4,5]. 2. Materials and methods The search for persons can be a special case of border control with X-rays. Cars, trucks, railway trains, containers and even ships and helicopters have undergone examination. Different radiation sources have been applied [6–8]: • Accelerators (5 and 10 MeV); units of X-ray therapy, which have been adapted for “control imaging” (Container fluo∗
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.2007.03.038
roscopy in Hamburg and in Rosenheim, Bavaria; producer Smith–Heimann); • X-ray tubes/accelerators (≤1 Mev), developed for vehicle fluoroscopy (USA, Mexico, manufacturer AS&E, Vacis, SAIC); • Cobalt 60, permanent radiator (1.11 MeV, half-life time 5.11 years) for vehicle and container control in China (offered by a Swedish partner of a Chinese company as cheap solution for Europe) and for railway train control at the border of Honduras–Mexico; • Caesium 137, permanent radiator (600 MeV, half-life time 3 years) for vehicle and truck control at the inner German border by the Stasi until 1989. The units are mobile or stationary. They produce fluoroscopic transmission images and backscatter images, or the combination of both at the same time. Backscatter imaging has the advantage that radiation source and detector are placed together on one side only and can thus bypass a vehicle under examination much more inconspicuously than other systems with wide separation of tube and detector. Mobile units are sold in form of a van, which is run by one person (the driver) only. The examples have been contributed by the manufacturers Smith–Heimann, AS&E, Vacis, SAIC and China. The details about the “control imaging” at the inner German border come from the expertise of the Strahlenschutzkommission (commission for X-ray protection), from the reports of the Birthler–Beh¨orde and from the media. Information about projects in Germany was contributed by German officials in
H. Vogel / European Journal of Radiology 63 (2007) 220–226
221
3.1. Autos
Fig. 3.1.1. Transmission image of a jeep. Oblique projection. Seats, wheels, motor and gas tank are visible. A person would be seen. China, radiation source cobalt 60.
Lower Saxony (Genehmigungsbeh¨orde in Niedersachsen) and ¨ in Hamburg [8–12]. by the official control organs (TUV) 3. Results For the hiding, a human being space of at least the person’s size has to be provided. This also determines the minimal resolution of the imaging device: the resolution must be sufficient to visualise details/rooms of such a space and to decide whether a human being could be hiding in there. The possibility to recognise more details, which allow ascertaining a hidden person, is an important advantage. The minimal resolution was realised with the equipment of the Stasi at the inner German border. The radiation source was caesium 137, producing a fan beam adjusted to a line with 110 detectors. The equipment covered a special lane, to which cars were ordered for control. Its resolution allowed identifying zones with higher absorption without showing details; inspection followed. This procedure breached the transit treaty, which limited the control to cases of suspicion; instead, the Stasi claimed that trespassing had to be expected all the time, so everybody could be held suspect.
Fig. 3.1.2.
Fig. 3.1.3.
**
**
The transmission images produced with fluoroscopy show superimposition of many details (Fig. 3.1.1). Humans would be recognised, nevertheless. The equipment from China allows modifying the direction of the fan beam by displacing the radiation source upwards or downwards, so superimposition could be avoided by control fluoroscopy. The second projection, however, is not in right angle to the primary projection [10]. Images produced with backscatter technique appear clearer. Because a human being is large in relation to the automobile’s size, he is clearly visible (Fig. 3.1.2). However, even backscatter imaging does not allow differentiating between a dead or a living person [8]. In backscatter imaging, the fact that the radiation source and the detector are on the same side of the searched car, allows controlling parked cars. This is possible with a van, which transports both (Fig. 3.1.3). This could be an advantage if large numbers of vehicles have to be controlled in short time. 3.2. Trucks When searching for people hidden in a truck one has to have in mind, that a person is smaller in relation to the size of the truck, than in relation to that of a passenger-car. Superimposition can impede recognition. A person who is surrounded by a large empty space is easy to recognise, which is easy to accept, looking at the person on the cargo-space area beside the load in Fig. 3.2.1. Large anatomic details become visible, and even smaller pathologic findings can be recognised in some individual cases [10]. Comparing both techniques one can conclude that the backscatter images show the person more clearly [8], if they are in the right plane (Fig. 3.2.2). The backscatter images even
Coffin or box, living or corpse. Backscatter image.
Control of parked autos with a mobile backscatter unit in a van. In the rear trunk of the first car a person is hiding.
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H. Vogel / European Journal of Radiology 63 (2007) 220–226
Fig. 3.2.1. a and b: Transmission image of the load of a truck. In the box on the left, household and personal effects can be recognised. Beside the box the service engineer is seated holding a painting; he wants to demonstrate that the exposure dose is low and that there is no reason for fear. The enlargement (b) of the person shows a diaphragmatic hernia and opacification of both knees due to water (he is suffering from arthrosis)–which explains why he is seated.
Fig. 3.2.2. ** Bananas and men in a container on a truck. The scout view visualises a hollow space in the front half of the container. The enlargement shows seated men and one person upright bent forward. On the second enlargement, the persons’ vertebral column, the lungs and the heart can be recognised. Backscatter image, North America.
Fig. 3.2.3. ** Human being (arrow) in a hollow space large as a coffin, at the bottom of the charging space at the back of the driver’s cabin. The silhouette of the person can just be imagined. Backscatter image. North Armerica.
H. Vogel / European Journal of Radiology 63 (2007) 220–226
Fig. 3.3.1.
**
223
Transmission imaging combined with backscatter imaging. Stationary unit for trucks and containers.
Fig. 3.3.2. ** Human beings in a container. At the left border of the image, the exhaust pipe of the truck; thereafter, the anterior container wall. In the container, a box with several persons possibly playing cards. Backscatter image. North America.
allow recognition of the persons’ spine and of his heart. The differentiation between a puppet and a human being also becomes possible. Fig. 3.2.3. If the hollow space is small, it may be difficult to discover a single person (Fig. 3.3.4) when filling-up this space.
Comparing transmission images with backscatter images (Fig. 3.3.6), the backscatter image is clearer, and more details can be recognised [8]. The transmission image of a truck has its limits in superimposition. The backscatter image allows recognition of the bananas, but people are also visible. The transmission image just shows a general load, the bananas themselves can-
3.3. Containers Units for transmission imaging for trucks and containers are mostly stationary (Fig. 3.3.1). For the search of human beings in containers, the same is valid as for that in trucks; superimposition limits recognition. Persons in large hollow spaces surrounded by air are easy to recognise (Fig. 3.3.2). High resolution is not obligatory for essential findings. In the container there are several humans, having died from suffocation (Fig. 3.3.3). According to the official loading documents, the cargo had been sent from China to Great Britain. Backscatter imaging with mobile units allows easy control of containers in inconspicuous “casual” passing (Fig. 3.3.4). The control units are widely employed at the southern border of the USA (Fig. 3.3.5).
Fig. 3.3.3. Transmission image with low resolution. Illegal aliens can be seen. They were suffocated trying to enter Great Britain.
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H. Vogel / European Journal of Radiology 63 (2007) 220–226
Fig. 3.3.4.
**
Backscatter imaging of containers with a mobile unit. North America.
not be identified; and only an empty space is recognisable, but its possible content is up for guessing, let alone permit even an estimate of its quantity, here of people in hiding. 3.4. Railway wagons
Fig. 3.3.5. Localisation of mobile and stationary units for control imaging of trucks and containers. Advertisement of AS&E.
Railway wagons are controlled with X-rays and gamma-rays producing transmission images and backscatter images. In an empty wagon and in a large hollow space (between packing cases), people can be discovered easily (Figs. 3.4.1 and 3.4.2). If the wagons were fully loaded, this would be difficult. It is obvious that the backscatter image shows one simple layer only of a limited depth. In Fig. 3.4.2 the anterior wall of the next row of the packing cases is visible, which narrows down the hollow space with the two persons. The opposite wall of the wagon and the interior of the packing cases beside the hollow space cannot be seen. Transmission imaging of railway wagons is performed with a fan beam adjusted to a line of detectors. Normally only a horizontal projection is obtained (Fig. 3.4.3). 3.5. Others Objects like airplanes, helicopters (Fig. 3.5.1) and ships are difficult to be controlled with imaging methods. Transmission imaging poses the problem to place the radiation source on one side and the detector on the other. Stationary units must be voluminous and will be expensive. The passage per hour would be limited. Backscatter imaging with mobile units offer at least sometimes the possibility of (partial) control imaging. 4. Discussion
**
Fig. 3.3.6. Transmission and backscatter image compared. The backscatter image (on top) shows the hollow spaces in the load of bananas. Details can be recognised which are on the side of the spectator (look for the wheels). The persons’ silhouettes and even single bananas are visible. The transmission image (below) shows the hollow spaces. Knowing the backscatter image, the heads of the persons can be imagined, bananas cannot be identified. In the hollow spaces, the number of persons is difficult to guess.
“Control imaging” in search of persons with X-rays and gamma-rays is done for different reasons [1,4,5,7–10,12]. Among them one finds: • Combat against criminality; • Migration accompanying globalisation; • Fight against terror.
H. Vogel / European Journal of Radiology 63 (2007) 220–226
Fig. 3.4.1.
***
225
Railway wagon with illegal aliens. The form of the wagon’s loading spaces indicates design for coal or grain transport. Border Honduras–Mexico.
Fig. 3.4.2. ** Railway wagon. Humans between packing cases. Backscatter image. The wagons part near to the spectator is visualised. The depth of the visualised layer can be guessed, considering the size of the persons and that of the packing cases. The wagon’s opposite wall and the interior of the packing cases cannot be seen.
Special aspects concern: • Prevention of death by suffocation and dehydration of stowaways; • Illegal transport of persons by foreign governments (recent discussion about kidnapping and transport of European citizens by non European countries, the historical well-known case the kidnapping of Rudolph Eichmann by Israel and his transport in diplomatic luggage from South America to Israel). In combat against criminality, the search for persons with X-rays may be a valuable tool: 2002, in Washington D.C and neighbouring states, Lee Boyd Malvo and John Allen Muham-
Fig. 3.4.3. Transmission imaging with cobalt 60. The controlled railway wagons show a funnel form similar to that in Fig. 3.4.1. The train passes slowly with constant speed through a fan beam between a line of detectors on a column (foreground) and the radiation source (in the background).
mad killed several persons in their gardens, at supermarkets and gas stations, one of killers did the shooting while hiding in the car while the other was driving it. The police blocked the roads and controlled the cars in search of the snipers and their weapon. The many traffic blocks and delays caused by this would have been much less severe, had this control been performed with transmission and backscatter imaging in mobile control units. Migration can be taken as part of globalisation; both create fears in parts of the populations of the rich countries. X-rays may help to discover illegal aliens. Politicians act, they try to prevent immigration from Africa into Europe in Africa, and at the country’s borders. Tragedies are frequently reported by the media. “Control imaging” offers the argument that by discovering the stow-aways, their lives can be saved (from death by suffocation and dehydration) and immigration is controlled (and prevented). The media and the public enforce these actions. A recent example is known from France and England: the French placed the illegal aliens’ camp directly beside the tunnel connecting Calais with Dover. They wanted to enforce a change on the British procedures for immigration. The British tried to control the trains and the Chunnel. Transmission imaging of the trains could not prevent attempts of the illegal aliens to enter Britain. After several tragic deaths, the British had to give in and change their procedures. The fight against terror is paramount. X-rays may help to find hidden people. A special aspect concerns the transport of persons (against their wish) across countries borders without seeking consent the authorities of the border states. Well known is the transport of Adolf Eichmann from Argentina to Israel, in diplomatic ¨ luggage in 1960; and in 1999, of the Kurdish leader, Ocalan,
Fig. 3.5.1. ** Helicopter. Backscatter image. The pilot’s seat and the engine block are visible. A hiding person would be discovered.
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H. Vogel / European Journal of Radiology 63 (2007) 220–226
from Nairobi, Africa, to Turkey. Both were made defenceless by narcotics. Here are connections to the persons being transported to secret prisons in foreign countries like the German Khaled al-Masri, who, in 2003, being suspected to cooperate with Al Quaida, was flown by USA agents from Macedonia to Afghanistan for interrogation. These cases are part of a discussion; concerning how a sovereign nation has to deal with this. It is thinkable that automatic controls with X-ray imaging will be imposed at airports and border stations. The former German democratic republic installed transmission-imaging units at 17 out of 27 control stations at the inner German border [2,3]. Diplomatic luggage and diplomatic cars were searched with X-rays, bypassing international conventions. The technology is easy to handle, nobody has to be a specially trained radiologist in order to recognise a human being [7]. Therefore, it is consequent that in the State of Hessen, Germany, prison authorities planned to control outgoing laundry with transmission imaging. Cases with laundry had being recently used for escape by prisoners. The attempt was legally refuted because there was no law justifying exposing persons to X-rays in order to prevent evasion. The argument that only laundry would be exposed was not thought valid enough. ** with friendly permission of AS&E. *** with friendly permission of SAIC. References [1] Brogdon BG, Vogel H. Search of the person. In: Brogdon BG, Vogel HHH, McDowell JD, editors. A radiologic atlas of abuse, torture, terrorism, an inflicted trauma. CRC Press; 2003. p. 301–8.
[2] Eisenfeld B. Einsatz von R¨ontgenstrahler und radioaktiven Stoffen durch das Ministerium f¨ur Staatssicherheit gegen Oppositionelle–Fiktion der Realit¨at? Berlin: Projektgruppe Strahlen; 2000. [3] Halter H. Es gibt kein Entrinnen – u¨ ber die radioaktiven Grenzkrontrollen der DDR. Spiegel 1994;51:176. [4] Roos G. Ministerium f¨ur UUmwel, Forsten und Verbraucherschutz. Mainz Oral communication; 2003. ¨ [5] Kreienfeld H. Technischer Uberwachungsverein Hamburg. Oral Communication; 2005. [6] Hupe O, Ankerhold U (2006). Determination of ambient and personal dose equivalent for personal and cargo security screening. Oxford Journals. Radiation Protection Dosimetry. 12 may 2006. [7] Lotz P. Durchleuchtung an Grenzen. Die Containerdurchleuchtungsanlage am Hamburger Hafen. Hamburg: Diss; 2002. [8] Rothschild PJ. Backscatter techniques – an alternative to body search. In: EU (2003), Radiation Protection Nr. 130 – Medicolegal exposures with ionising radiation without medical indication. Proceedings of the International Symposium. 2002. p. 31–8. [9] Lipoti J. Detection of weapons. In: EU (2003) Radiation Protection Nr. 130–Medicolegal exposures with ionising radiation without medical indication. Proceedings of the International Symposium. 2002. p. 48– 55. [10] Magnusson T. The role of X-rays in drug detection. In: EU (2003), Radiation Protection Nr. 130 – Medicolegal exposures with ionising radiation without medical indication. Proceedings of the International Symposium. 2002. p. 56–8. [11] Strahlenschutzkommission (1995) Stellungnahme der Strahlenschutzkommission: Strahlenrisiko durch ehemalige DDR-Grenzkontrollen mittels Cs-137-Strahlung. Ver¨offentlichungen der Strahlenschutzkommission, Bad. 39 (Verabschiedet in der 129. Sitzung am 17.02. 1995). [12] Rogers K. The use of transmission- based technology in the detection of clandestine entrants. In: EU (2003), Radiation Protection Nr. 130–Medicolegal exposures with ionising radiation without medical indication. Proceedings of the International Symposium. 2002. p. 39– 40.
Search for persons H. Vogel ∗ Asklepios Klinik St. Georg, Radiology, Lohm¨uhlenstr. 5 20099 Hamburg, Germany Received 3 March 2007; received in revised form 4 March 2007; accepted 5 March 2007
Abstract X-rays and gamma-rays are used to detect hidden persons in vehicles, containers, and railway wagons. They are produced with accelerators, X-ray tubes, cobalt 60 and caesium 137. Fan beams adjusted to a line of digital detectors produce the image. The resolution is sufficient to recognise a human being. The recognition of persons with transmission images is limited by superimposition; backscatter imaging produces clearer images but of one single layer only. The future will bring new applications of search for persons with X-rays. Crimes and terrorist attacks will induce added demand for security, where search with X-rays and gamma-rays will keep its important role or even increase it. © 2007 Published by Elsevier Ireland Ltd. Keywords: Search for persons; Transmission imaging; Backscatter imaging; Imaging with cobalt 60; Imaging with caesium 137
1. Introduction The search for humans serves two goals: detection and protection. Illegal aliens shall be detected and stow-aways shall not perish in their hiding place [1]. Tragedies have become known when citizens of the communist German democratic republic were detected, when fleeing to the west. Some of them were discovered by control units, which produced transmission images of trucks and cars with gamma-rays help of caesium 137 [2,3]. Border controls with gamma- or X-rays are quite common; they have been practised in North America, at the Chunnel between Calais and Dover (when France placed the camp for asylum seekers directly beside the railways to England), in Germany a prison in Hesse tried to implement laundry control with X-rays, because detainees used the laundry boxes for escape [4,5]. 2. Materials and methods The search for persons can be a special case of border control with X-rays. Cars, trucks, railway trains, containers and even ships and helicopters have undergone examination. Different radiation sources have been applied [6–8]: • Accelerators (5 and 10 MeV); units of X-ray therapy, which have been adapted for “control imaging” (Container fluo∗
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.2007.03.038
roscopy in Hamburg and in Rosenheim, Bavaria; producer Smith–Heimann); • X-ray tubes/accelerators (≤1 Mev), developed for vehicle fluoroscopy (USA, Mexico, manufacturer AS&E, Vacis, SAIC); • Cobalt 60, permanent radiator (1.11 MeV, half-life time 5.11 years) for vehicle and container control in China (offered by a Swedish partner of a Chinese company as cheap solution for Europe) and for railway train control at the border of Honduras–Mexico; • Caesium 137, permanent radiator (600 MeV, half-life time 3 years) for vehicle and truck control at the inner German border by the Stasi until 1989. The units are mobile or stationary. They produce fluoroscopic transmission images and backscatter images, or the combination of both at the same time. Backscatter imaging has the advantage that radiation source and detector are placed together on one side only and can thus bypass a vehicle under examination much more inconspicuously than other systems with wide separation of tube and detector. Mobile units are sold in form of a van, which is run by one person (the driver) only. The examples have been contributed by the manufacturers Smith–Heimann, AS&E, Vacis, SAIC and China. The details about the “control imaging” at the inner German border come from the expertise of the Strahlenschutzkommission (commission for X-ray protection), from the reports of the Birthler–Beh¨orde and from the media. Information about projects in Germany was contributed by German officials in
H. Vogel / European Journal of Radiology 63 (2007) 220–226
221
3.1. Autos
Fig. 3.1.1. Transmission image of a jeep. Oblique projection. Seats, wheels, motor and gas tank are visible. A person would be seen. China, radiation source cobalt 60.
Lower Saxony (Genehmigungsbeh¨orde in Niedersachsen) and ¨ in Hamburg [8–12]. by the official control organs (TUV) 3. Results For the hiding, a human being space of at least the person’s size has to be provided. This also determines the minimal resolution of the imaging device: the resolution must be sufficient to visualise details/rooms of such a space and to decide whether a human being could be hiding in there. The possibility to recognise more details, which allow ascertaining a hidden person, is an important advantage. The minimal resolution was realised with the equipment of the Stasi at the inner German border. The radiation source was caesium 137, producing a fan beam adjusted to a line with 110 detectors. The equipment covered a special lane, to which cars were ordered for control. Its resolution allowed identifying zones with higher absorption without showing details; inspection followed. This procedure breached the transit treaty, which limited the control to cases of suspicion; instead, the Stasi claimed that trespassing had to be expected all the time, so everybody could be held suspect.
Fig. 3.1.2.
Fig. 3.1.3.
**
**
The transmission images produced with fluoroscopy show superimposition of many details (Fig. 3.1.1). Humans would be recognised, nevertheless. The equipment from China allows modifying the direction of the fan beam by displacing the radiation source upwards or downwards, so superimposition could be avoided by control fluoroscopy. The second projection, however, is not in right angle to the primary projection [10]. Images produced with backscatter technique appear clearer. Because a human being is large in relation to the automobile’s size, he is clearly visible (Fig. 3.1.2). However, even backscatter imaging does not allow differentiating between a dead or a living person [8]. In backscatter imaging, the fact that the radiation source and the detector are on the same side of the searched car, allows controlling parked cars. This is possible with a van, which transports both (Fig. 3.1.3). This could be an advantage if large numbers of vehicles have to be controlled in short time. 3.2. Trucks When searching for people hidden in a truck one has to have in mind, that a person is smaller in relation to the size of the truck, than in relation to that of a passenger-car. Superimposition can impede recognition. A person who is surrounded by a large empty space is easy to recognise, which is easy to accept, looking at the person on the cargo-space area beside the load in Fig. 3.2.1. Large anatomic details become visible, and even smaller pathologic findings can be recognised in some individual cases [10]. Comparing both techniques one can conclude that the backscatter images show the person more clearly [8], if they are in the right plane (Fig. 3.2.2). The backscatter images even
Coffin or box, living or corpse. Backscatter image.
Control of parked autos with a mobile backscatter unit in a van. In the rear trunk of the first car a person is hiding.
222
H. Vogel / European Journal of Radiology 63 (2007) 220–226
Fig. 3.2.1. a and b: Transmission image of the load of a truck. In the box on the left, household and personal effects can be recognised. Beside the box the service engineer is seated holding a painting; he wants to demonstrate that the exposure dose is low and that there is no reason for fear. The enlargement (b) of the person shows a diaphragmatic hernia and opacification of both knees due to water (he is suffering from arthrosis)–which explains why he is seated.
Fig. 3.2.2. ** Bananas and men in a container on a truck. The scout view visualises a hollow space in the front half of the container. The enlargement shows seated men and one person upright bent forward. On the second enlargement, the persons’ vertebral column, the lungs and the heart can be recognised. Backscatter image, North America.
Fig. 3.2.3. ** Human being (arrow) in a hollow space large as a coffin, at the bottom of the charging space at the back of the driver’s cabin. The silhouette of the person can just be imagined. Backscatter image. North Armerica.
H. Vogel / European Journal of Radiology 63 (2007) 220–226
Fig. 3.3.1.
**
223
Transmission imaging combined with backscatter imaging. Stationary unit for trucks and containers.
Fig. 3.3.2. ** Human beings in a container. At the left border of the image, the exhaust pipe of the truck; thereafter, the anterior container wall. In the container, a box with several persons possibly playing cards. Backscatter image. North America.
allow recognition of the persons’ spine and of his heart. The differentiation between a puppet and a human being also becomes possible. Fig. 3.2.3. If the hollow space is small, it may be difficult to discover a single person (Fig. 3.3.4) when filling-up this space.
Comparing transmission images with backscatter images (Fig. 3.3.6), the backscatter image is clearer, and more details can be recognised [8]. The transmission image of a truck has its limits in superimposition. The backscatter image allows recognition of the bananas, but people are also visible. The transmission image just shows a general load, the bananas themselves can-
3.3. Containers Units for transmission imaging for trucks and containers are mostly stationary (Fig. 3.3.1). For the search of human beings in containers, the same is valid as for that in trucks; superimposition limits recognition. Persons in large hollow spaces surrounded by air are easy to recognise (Fig. 3.3.2). High resolution is not obligatory for essential findings. In the container there are several humans, having died from suffocation (Fig. 3.3.3). According to the official loading documents, the cargo had been sent from China to Great Britain. Backscatter imaging with mobile units allows easy control of containers in inconspicuous “casual” passing (Fig. 3.3.4). The control units are widely employed at the southern border of the USA (Fig. 3.3.5).
Fig. 3.3.3. Transmission image with low resolution. Illegal aliens can be seen. They were suffocated trying to enter Great Britain.
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H. Vogel / European Journal of Radiology 63 (2007) 220–226
Fig. 3.3.4.
**
Backscatter imaging of containers with a mobile unit. North America.
not be identified; and only an empty space is recognisable, but its possible content is up for guessing, let alone permit even an estimate of its quantity, here of people in hiding. 3.4. Railway wagons
Fig. 3.3.5. Localisation of mobile and stationary units for control imaging of trucks and containers. Advertisement of AS&E.
Railway wagons are controlled with X-rays and gamma-rays producing transmission images and backscatter images. In an empty wagon and in a large hollow space (between packing cases), people can be discovered easily (Figs. 3.4.1 and 3.4.2). If the wagons were fully loaded, this would be difficult. It is obvious that the backscatter image shows one simple layer only of a limited depth. In Fig. 3.4.2 the anterior wall of the next row of the packing cases is visible, which narrows down the hollow space with the two persons. The opposite wall of the wagon and the interior of the packing cases beside the hollow space cannot be seen. Transmission imaging of railway wagons is performed with a fan beam adjusted to a line of detectors. Normally only a horizontal projection is obtained (Fig. 3.4.3). 3.5. Others Objects like airplanes, helicopters (Fig. 3.5.1) and ships are difficult to be controlled with imaging methods. Transmission imaging poses the problem to place the radiation source on one side and the detector on the other. Stationary units must be voluminous and will be expensive. The passage per hour would be limited. Backscatter imaging with mobile units offer at least sometimes the possibility of (partial) control imaging. 4. Discussion
**
Fig. 3.3.6. Transmission and backscatter image compared. The backscatter image (on top) shows the hollow spaces in the load of bananas. Details can be recognised which are on the side of the spectator (look for the wheels). The persons’ silhouettes and even single bananas are visible. The transmission image (below) shows the hollow spaces. Knowing the backscatter image, the heads of the persons can be imagined, bananas cannot be identified. In the hollow spaces, the number of persons is difficult to guess.
“Control imaging” in search of persons with X-rays and gamma-rays is done for different reasons [1,4,5,7–10,12]. Among them one finds: • Combat against criminality; • Migration accompanying globalisation; • Fight against terror.
H. Vogel / European Journal of Radiology 63 (2007) 220–226
Fig. 3.4.1.
***
225
Railway wagon with illegal aliens. The form of the wagon’s loading spaces indicates design for coal or grain transport. Border Honduras–Mexico.
Fig. 3.4.2. ** Railway wagon. Humans between packing cases. Backscatter image. The wagons part near to the spectator is visualised. The depth of the visualised layer can be guessed, considering the size of the persons and that of the packing cases. The wagon’s opposite wall and the interior of the packing cases cannot be seen.
Special aspects concern: • Prevention of death by suffocation and dehydration of stowaways; • Illegal transport of persons by foreign governments (recent discussion about kidnapping and transport of European citizens by non European countries, the historical well-known case the kidnapping of Rudolph Eichmann by Israel and his transport in diplomatic luggage from South America to Israel). In combat against criminality, the search for persons with X-rays may be a valuable tool: 2002, in Washington D.C and neighbouring states, Lee Boyd Malvo and John Allen Muham-
Fig. 3.4.3. Transmission imaging with cobalt 60. The controlled railway wagons show a funnel form similar to that in Fig. 3.4.1. The train passes slowly with constant speed through a fan beam between a line of detectors on a column (foreground) and the radiation source (in the background).
mad killed several persons in their gardens, at supermarkets and gas stations, one of killers did the shooting while hiding in the car while the other was driving it. The police blocked the roads and controlled the cars in search of the snipers and their weapon. The many traffic blocks and delays caused by this would have been much less severe, had this control been performed with transmission and backscatter imaging in mobile control units. Migration can be taken as part of globalisation; both create fears in parts of the populations of the rich countries. X-rays may help to discover illegal aliens. Politicians act, they try to prevent immigration from Africa into Europe in Africa, and at the country’s borders. Tragedies are frequently reported by the media. “Control imaging” offers the argument that by discovering the stow-aways, their lives can be saved (from death by suffocation and dehydration) and immigration is controlled (and prevented). The media and the public enforce these actions. A recent example is known from France and England: the French placed the illegal aliens’ camp directly beside the tunnel connecting Calais with Dover. They wanted to enforce a change on the British procedures for immigration. The British tried to control the trains and the Chunnel. Transmission imaging of the trains could not prevent attempts of the illegal aliens to enter Britain. After several tragic deaths, the British had to give in and change their procedures. The fight against terror is paramount. X-rays may help to find hidden people. A special aspect concerns the transport of persons (against their wish) across countries borders without seeking consent the authorities of the border states. Well known is the transport of Adolf Eichmann from Argentina to Israel, in diplomatic ¨ luggage in 1960; and in 1999, of the Kurdish leader, Ocalan,
Fig. 3.5.1. ** Helicopter. Backscatter image. The pilot’s seat and the engine block are visible. A hiding person would be discovered.
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from Nairobi, Africa, to Turkey. Both were made defenceless by narcotics. Here are connections to the persons being transported to secret prisons in foreign countries like the German Khaled al-Masri, who, in 2003, being suspected to cooperate with Al Quaida, was flown by USA agents from Macedonia to Afghanistan for interrogation. These cases are part of a discussion; concerning how a sovereign nation has to deal with this. It is thinkable that automatic controls with X-ray imaging will be imposed at airports and border stations. The former German democratic republic installed transmission-imaging units at 17 out of 27 control stations at the inner German border [2,3]. Diplomatic luggage and diplomatic cars were searched with X-rays, bypassing international conventions. The technology is easy to handle, nobody has to be a specially trained radiologist in order to recognise a human being [7]. Therefore, it is consequent that in the State of Hessen, Germany, prison authorities planned to control outgoing laundry with transmission imaging. Cases with laundry had being recently used for escape by prisoners. The attempt was legally refuted because there was no law justifying exposing persons to X-rays in order to prevent evasion. The argument that only laundry would be exposed was not thought valid enough. ** with friendly permission of AS&E. *** with friendly permission of SAIC. References [1] Brogdon BG, Vogel H. Search of the person. In: Brogdon BG, Vogel HHH, McDowell JD, editors. A radiologic atlas of abuse, torture, terrorism, an inflicted trauma. CRC Press; 2003. p. 301–8.
[2] Eisenfeld B. Einsatz von R¨ontgenstrahler und radioaktiven Stoffen durch das Ministerium f¨ur Staatssicherheit gegen Oppositionelle–Fiktion der Realit¨at? Berlin: Projektgruppe Strahlen; 2000. [3] Halter H. Es gibt kein Entrinnen – u¨ ber die radioaktiven Grenzkrontrollen der DDR. Spiegel 1994;51:176. [4] Roos G. Ministerium f¨ur UUmwel, Forsten und Verbraucherschutz. Mainz Oral communication; 2003. ¨ [5] Kreienfeld H. Technischer Uberwachungsverein Hamburg. Oral Communication; 2005. [6] Hupe O, Ankerhold U (2006). Determination of ambient and personal dose equivalent for personal and cargo security screening. Oxford Journals. Radiation Protection Dosimetry. 12 may 2006. [7] Lotz P. Durchleuchtung an Grenzen. Die Containerdurchleuchtungsanlage am Hamburger Hafen. Hamburg: Diss; 2002. [8] Rothschild PJ. Backscatter techniques – an alternative to body search. In: EU (2003), Radiation Protection Nr. 130 – Medicolegal exposures with ionising radiation without medical indication. Proceedings of the International Symposium. 2002. p. 31–8. [9] Lipoti J. Detection of weapons. In: EU (2003) Radiation Protection Nr. 130–Medicolegal exposures with ionising radiation without medical indication. Proceedings of the International Symposium. 2002. p. 48– 55. [10] Magnusson T. The role of X-rays in drug detection. In: EU (2003), Radiation Protection Nr. 130 – Medicolegal exposures with ionising radiation without medical indication. Proceedings of the International Symposium. 2002. p. 56–8. [11] Strahlenschutzkommission (1995) Stellungnahme der Strahlenschutzkommission: Strahlenrisiko durch ehemalige DDR-Grenzkontrollen mittels Cs-137-Strahlung. Ver¨offentlichungen der Strahlenschutzkommission, Bad. 39 (Verabschiedet in der 129. Sitzung am 17.02. 1995). [12] Rogers K. The use of transmission- based technology in the detection of clandestine entrants. In: EU (2003), Radiation Protection Nr. 130–Medicolegal exposures with ionising radiation without medical indication. Proceedings of the International Symposium. 2002. p. 39– 40.