Guide to X-Ray Inspection

Yes X-ray inspection systems are perfectly safe if you follow the intended use. The X5 X-ray series feature radiation protection to ensure that emissions are kept below 1 μSv/hour during operation. By their very nature, X-ray systems used for food inspection are safe and emissions are significantly less than many naturally occurring radiation sources such as medical X-rays, Radon gas, Gamma decay in rocks, cosmic rays and even the Sun. The world’s average “background” rate of radiation is around 2.7 mSv/yr. Working a 40 hour week for 48 weeks per year next to a LOMA X-Ray system equates to 0.78mSv/yr less. A transatlantic flight for 8 hours provides a much higher dose of radiation than a Loma X-ray inspection system. You can read more information about are X-rays safe for food production here.

As with any food inspection system, it depends on the application, where you want to inspect within the production process, the size of your product and what foreign contaminants you are looking to detect. Loma’s X5 X-ray systems are available for a wide range of applications including bulk, packaged, loose and pumped products, for different industries. As an example: If you are looking at a solution within primary processing making sausages, to try and get the best detection of contaminants (such as bone), and to remove waste before it goes through other costly processes, it would be worth considering an X5 Pipeline to be used near the beginning of the process.

When installing an X-ray inspection system into a factory for the first time there are varying requirements depending on your location, but one of our representatives can talk you through the easy processes. For the relevant information in your area please contact your local Loma office or distributor. Below is an example based on the United Kingdom.

• Your X-ray system will need to be registered with the Local Health and Safety Executive prior to use.  (Details on your local health and safety executive can be found here)
• You will need to consult and appoint a Radiation Protection Adviser (RPA) prior to turning the machine on. Organisations who offer this service in the UK include Radman Associates or Public
• Health England (PHE).  
• Your RPA will work with you to do the following:
• Draw up your local rules (what you can and can’t do onsite relating to your application and equipment)
• Complete a Risk Assessment
• Train your appointed Radiation Protection Supervisors RPS (An RPS must be present at all times whilst the X-rays are running)
• This process will take around 28 days, depending on the availability of your chosen RPA.  Once the system is up and running, you are required to carry out radiation tests at regular intervals outlined by your RPA.

Just like metal detection, there are two types of calibration associated with X-ray systems. Firstly in order to maintain designated Codes of Practice or HACCP protocols, X-ray systems should be calibrated once a year to normalize the detector and make sure the system is working correctly. Secondly an X-ray system will need to be calibrated for every new product so that the system can ‘learn the product’ and set up limits to achieve the best contaminant detection size possible. Once a product has been learnt once, it can then be recalled at the click of a button with no need to relearn unless there is a change in the product or if an error occurs.

Although both X-ray inspection and metal detection are used to check for contaminants within food and pharmaceutical products, the technologies have different capabilities and advantages. Each technology will be important for different reasons depending on the application and situation. Metal detectors are principally used when only detection of metal contaminants is required, which is why they tend to be the cheaper option and as technology has moved on over the years the contaminant sizes that can be achieved are very good. Alternatively X-ray inspection systems offer the ability to not only detect for all metals, but also other contaminants such as bone, ceramic, glass and dense plastics. X-ray inspection is also capable of checking the product integrity – making sure the product is complete and free of defects. It is also worth noting X-ray inspection systems can typically reliably see smaller contaminants in harder to inspect products compared with a metal detector.

Yes, Loma’s X-ray systems have been designed to be easy to use to allow anyone with good health to operate the machine following basic training received when the system is first commissioned. It is recommended that pregnant women should NOT work in an area where an X-ray system is in operation. Just like metal detection, in order to have a deeper understanding of the system and its full capabilities pre-designed training courses are available at all levels including engineer and Subject Matter Experts (SME). It is worth noting that a Radiation Protection Supervisor (RPS) is always required to be present within your factory when the X-rays are running – for more details please see the question below.

X-ray is very versatile at finding different contaminants, but with plastic it depends on its characteristic and the type of product you are trying to inspect it within. The orientation of the plastic within the product impacts the ease of detection, for example if the plastic contaminant is in a horizontal orientation it will absorb fewer X-rays due to its density (thickness) and will not be detected. As a rule of thumb, if it floats, an X-ray system will not be able to detect that contaminant. This is the same for most makes and models of X-ray Inspection systems used within food production.

Yes, Loma’s X-ray inspection systems come with software built in, called X-weigh, which converts product density into weight which is great for certain applications such as yogurts and ready meals. For example if you are weighing a product that has two compartments a checkweigher will check the total weight, where a X-weigh will check each compartment separately providing both an individual and overall weight. This will let you know if there is too much of one component, which could be caused by an issue with a portioning machine, resulting in an inferior product. X-weigh does not conform with weights and measures so a checkweigher would be required to do the total overall weight check.

Stainless steel has a specific gravity of 7.7

Ferrous materials have a specific gravity of around 8.0

Non Ferrous (Brass or copper) materials have a specific gravity of around 8.8

From a Metal Detector point of view Ferrous, Non Ferrous and Stainless Steel have become standard test materials because of the different response they develop in a Metal Detector. Conversely, detectability of materials in X-ray systems are proportional to the specific gravity increase relative to the product; as can be seen all three materials are very close in density. Since Stainless Steel is both the lowest density of the above three materials and the most abundant in factories, it is generally accepted that this is the one test piece worthwhile testing. However, it is always a responsibility for any producer using a CCP to ensure that likely contaminants have been identified via HACCP risk assessment, so this should be additionally considered when selecting the contaminants used to challenge the CCP. Additionally, any specific customer requirements or supermarket specifications should be considered.

Note: Specific Gravity is defined as density normalised to water @ 1.0

LOMA's image processing software is designed to adapt to differences in product density, while maximizing sensitivity. This overcomes the problems associated with conventional systems.

X-ray inspection systems can detect more contaminants than Metal Detection systems, however there are a few limitations including:

• Low-density plastics
• Thin glass, such as fluorescent tubes
• Low-density stones
• Insects
• Wood
• Hair
• Cardboard
• Paper

All LOMA machines comply with national emission and safety regulations. When the machine is first installed a documented examination takes place. However, for peace of mind, a periodic examination is advised. As this is a relatively simple process it can be done each day without the need to stop the production line.

No, All of our systems meet the safety ratings of less than 1 µSv/h.

LOMA X-ray inspection systems are designed to operate continuously at speeds in excess of 600ppm or 90m/min (300ft/min).

Early X-Ray systems had reliability problems and were expensive. However, the involvement of mainstream inspection specialists like LOMA ensures that new-generation x-ray systems are as robust and reliable as conventional metal detectors with and excellent ROI.

In terms of contaminant detection, X-ray systems will detect lower levels of contaminants. They can also detect a wide range of non-metallic contaminants including ceramic, bone, glass, stone and dens plastics. X-Ray Inspection systems can also check for product intermarry to see missing or damaged products.

No, LOMA X-ray Inspection systems are designed to be as easy to use as a Metal Detector.  Training is provided upon commissioning and additional onsite training can be arranged if required. (Please click here for more details)

No, the dosage a food product can be subjected to is governed by controls. LOMA X-ray inspection systems operate at around one millionth of the current limit.

Loma’s range of X-ray inspection systems are easy to use with intuitive full colour touchscreens and icon-driven menus as well as offering fast inspection and product set up, automatically optimising the systems for each product type allowing you to learn and switch within minutes.

X-ray systems also offer the ability to detect bone, glass, ceramic or stone and dense plastics whilst also checking for product integrity, making it the complete solution in contaminant detection.

Metal detection and X-ray inspection offer different capabilities – to assess which you should choose, you should carry out a Hazard Analysis and Critical Control Points audit. If the audit determines that metal is likely to be the only contaminant found, then a metal detector is likely to be the most cost-effective solution, however, if other issues such as packaging and product effect are raised by the audit then it is recommended you perform a full product test to establish the most suitable technology.

If, the audit determines that metal and other contaminants such as glass, mineral stone, calcified bone or high-density plastics and rubber are likely to be encountered, then X-ray is the only suitable solution. In many cases, there’s only one suitable solution. However, there may be occasions when it could be helpful to install both metal detection and X-ray inspection systems on the same production line.