It takes a particularly cowardly or unhinged type of person to send a package that will explode on opening and sprays nails in the face of the recipient or cuts their fingers. Unfortunately letterbombs are posted, explosive packages are delivered, letters are lined with razor blades and people are injured, or worse. Terrorists and lunatics do exist and some will feel justified in spiking an innocuous looking package with explosives or threatening people with a loaded gun in response to some perceived slight, or in protest. They may belong to a subversive political faction or just be an angry ex-employee, either way they will do their utmost to attain their goal. This self belief renders them extremely dangerous and willing to resort to underhand tactics desixgned to both disguise their intentions and ensure their success. Hence the need to properly secure sites which are vulnerable to attacks.

If the electronic scanner or x-ray screener is easy to use and rapidly processes all items passed through them, delays are insignificant and security should be assured. However, by definition, the detector must be able to detect and if it is not durable and reliable, the unthinkable could happen, and the user's company could be splashed across the front pages of the daily newspapers for all the wrong reasons. There is no room for error with these potentially life saving devices, so it is imperative the correct system for the job is installed.

Types of mailscanners

There are two main types of detection systems capable of discovering the contents of a packages or automatic 'electronic' scanners and and x-ray machines. Electronic scanners such as the SCANMAIL 10K are capable of distinguishing between potentially hazardous and harmless matters and can be programmed to operate at increased sensitivity in times of high security alerts. An x-ray machine will give an image of any item passed through it and advanced machines such as the SCANMAX COLORSCAN range offer zoom and colour highlighting for definition of suspect areas. Well designed, installed and operated units will almost certainly stop the criminals from achieving their aim, although how they actually work, and what they are capable of sensing, differs.

 

Types of x-ray scanner

There are two types of x-ray machine in use in mailrooms: cabinet machines and conveyor units. The former is suitable for screening letter, mailtrays and packages whilst the latter is found in organisations with a large mailing operations. Both units enable the operator to view the contents of a package on a screen and advanced systems are capable of highlighting suspicious areas.

Cabinet x-ray systems are an accurate means of discovering the contents of an envelop or parcel. Cabinet machines operate by shooting electrons across a glass tube at a Tungsten target contained in a vacuum chamber. When the electrons hit the target, light heat and x-ray s are generated. The x-rays travel down into the mail chamber, and penetrate anything contained in there. The number of x-rays to penetrate the contents of the chamber, without being absorbed by its contents, depends on the density and thickness of individual objects. Those x-rays that are not absorbed travel on to a fluorescent screen which converts them into visible radiation. Depending on the quantity of x-rays to hit the screen, an image of 'shadows' is produced. The system builds of a picture of the objects based on their density and is capable of differentiating between cardboard or fabrics (which absorb very few x-rays), aluminium and porcelain (more x-rays are absorbed) and steel and lead (all x-rays are absorbed).

For mailrooms needing to process a large quantity of mail and parcels as efficiently as possible means that heaving box after box into a cabinet would be an awkward and time consuming process. As such, an alternative system is available. Conveyor units begin to scan items after it passes through the lead curtains at the access point of the x-ray tube and breaks a light beam. Whilst in the tube, the baggage passes under a strip of diodes which repeatedly scan along a thin line until an image of the contents of the baggage is built up. Just prior to exiting the tube, another light beam is broken and the x-ray s are switched off. The mail then carries on through the egress lead curtains. One downside of using a conveyor system is that it requires 2 people to operate it effectively. One person is responsible for loading the mail on and off the conveyor belt whilst the second person operates the controls and examines the onscreen x-ray images.

Both these systems offer the user a high level of security as they enable any package to be scanned before it is opened . X-ray systems can range from small portable units suitable for checking suspicious packages found remote from a large fixed system (normally outdoors), though table top scanners suitable for letters and small parcels, up to large conveyor scanners found at building entrances and in large busy postrooms. The x-ray image on most modern systems such as the SCANMAX range can be viewed on a PC monitor, a CCTV monitor, or a hard copy print.

Safety

There are many myths surrounding x-ray systems, almost all of which are unfounded. The modern x-ray unit is a safe security option that offers unrivaled protection against all manner of nasty surprises. These units are leadlined to a thickness required by the British Standards and contain safety features designed to ensure that the system cannot operate unless all doors a locked. LEDs and visual PC alarms also act as safety backups. In the unlikely event of someone placing a hand in the x-ray unit while it is in operation or a child jumping on the conveyor belt at an airport, emergency stop buttons automatically shut down the system.

In any case, the level of x-rays used in these detection systems is low and again, is fixed by regulations. In fact, it is so low that any dose of radiation received by a member of staff working with these units would not register on a dose meter. The dose rate on the outer surface of the unit is less than on microsievert, - according to the National Radiological Protection Board, this is equivalent to one tenth the dose which would be incurred by flying from the UK to Spain.

Aside from the system itself it is very important to ensure that anyone operating the machines is aware of the safety precautions, and follows them at all times. The user must employ a Radiation Protection Supervisor to oversee the running of the system and ensure that all health and safety procedures are followed. If they are, and the correct option is installed, the user will benefit through the added security an x-ray system provides.

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