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Guide to X-Ray Inspection

LOMA SYSTEMS® offers this guide to X-Ray Inspection to assist food,packaging and pharmaceutical companies in understanding this remarkable technology and establishing an effective inspection program.

Why X-ray Inspection

Brand recognition and HACCP programs are becoming increasingly important in the food,packaging industries. Today, consumers and retailers alike are better informed and more focused on purchasing quality products. A contamination issue can have an impact on the brand image and the long-term success of a business.

HACCP programs can help prevent contamination, provided the proper technology and processes are in place. LOMA SYSTEMS is committed to providing the online contaminant detection systems required of many HACCP programs to protect your brand image and help your company win more business in the future.

There are three key reasons for investing in x-ray inspection:

  • The business benefits from more dynamic inspection performance and greater confidence in achieving compliance
  • Technical and marketing advantages are better than metal detection because x-ray systems can detect non-metallic contaminants
  • Operational advantages lend maximum inspection performance at high line speeds with reliability and online simplicity

Business Case

Protecting consumers, brand image, integrity while ensuring quality and compliance represents a significant cost to your business. With LOMA® X-Ray Inspection systems, you can improve quality and reduce overall compliance costs. You also have the opportunity to increase market share and revenue.

  • Ensure compliance with HACCP and retailer quality standards
  • Accurately demonstrate due diligence
  • Reduce recall costs
  • Avoid litigation
  • Increase your market share through customer confidence
  • Improve customer satisfaction and retention
  • Help you win new business where quality and compliance with the latest codes of practice is a key customer requirement

Technical Advantages

LOMA X-Ray Inspection systems detect metal contaminants better than metal detectors and detect non-metallic contaminants, as well as missing, underweight or broken products.

  • Metal detection is not affected by foil or metallic packaging
  • Excellent stainless steel detection
  • Immune to environmental effects
  • Detects non-metallic components such as glass, stone, calcified bone, plastics, rubber, ceramic, cement, pvc, etc.
  • Identifies missing product, low fill and broken product

Operational Advantages

LOMA X-Ray Inspection systems ensure 100% confidence in compliance, without stopping the production line. The systems are simple to use and support high production line speeds.

  • Production line speeds in excess of 600 packs per minute or 90m/min (300 ft/min)
  • Dynamic analysis maximizes performance and virtually eliminates false rejects
  • High speed computer maximizes throughput
  • Simple touch screen Windows interface designed for ease of use
  • Minimal training and product learn requirement
  • Increased operational flexibility with minimal set-up and changeover times
  • Ability to deal with product density variations and inspect randomly, produced products on a production run

X-Ray Inspection Performance (detection capability)

X-ray systems can detect the following non-exhaustive list of contaminants:

  • Metal
  • Non-ferrous metals in foil, including stainless steel
  • Glass
  • Bone (alcified)
  • PVC plastic
  • TFE (Teflon) plastic
  • Ceramic or concrete
  • Flavor/sugar clumps
  • Missing product


In most food-based products x-ray systems cannot detect the following materials:

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


X-ray systems are particularly suitable for quality control in the following sectors:

  • Ready Meals
  • Prepared foods
  • Meat 
  • Bakery Products
  • Cereals
  • Dairy foods
  • Confectionery
  • Vegetables
  • Fruit
  • Cosmetics


Global Food Inspection Capability

  • LOMA SYSTEMS is a world leader in the manufacture of metal detectors, checkweighers and x-ray inspection systems
  • 95% of LOMA’s x-ray inspection systems are sold to the food and packaging industries
  • LOMA has more than 30 years of experience in food and packaging industry inspection
  • LOMA X-Ray Inspection systems are used by 35 / 40 of the world’s largest food companies
  • LOMA X-Ray Inspection systems are installed in over 100 countries around the world

Advanced Technology

  • Utilize the same design concepts that make our metal detectors the choice of the world's largest food companies
  • Highly sensitive to both metallic and non-metallic contaminants
  • Features advanced image processing
  • Incorporates sophisticated sensor technology and detection software

Comprehensive Support

  • LOMA's international service and support network offers high-quality service and rapid response anywhere in the world
  • Remote diagnostics are available via a modem connection
  • Dedicated x-ray specialists provide guidance to help you meet compliance requirements
  • We offer a systems integration service to help you link x-ray inspection systems, processing equipment and management information systems into a single integrated solution
  • A range of flexible support packages can be tailored to your operating requirements, reducing downtime and ensuring systems operate at maximum efficiency

Principles of X-ray inspection

How X-rays Inspection Systems Work

An x-ray inspection system has three main components: a device to generate x-rays, a sensor to detect contaminants and a high-speed computer to process sensor data


X-rays are generated by a special glass tube that is cooled. When high voltage is applied to that tube, electrons are generated. The electrons then strike a target which emits a stream of x-rays that are focused and reduced to a fan beam. The fan beam passes through the product before entering a sensor. The sensor then converts the x-ray signal into a form where it can be passed to a computer for processing and detection.


  • X-ray systems detect contaminants by density difference
  • As an x-ray penetrates a product, it loses some of its energy
  • A dense area such as a contaminant will reduce the energy even further
  • As the x-ray exits the product, it reaches the sensor - an array of photo-diodes that precisely measure the x-ray energy that reaches them
  • The sensor converts the energy signal into a grey-scale image
  • A high-speed computer scans the sensor at thousands of times per second and stores the individual signals
  • It compares them to a dynamic value that delivers the maximum level of sensitivity and minimum level of false readings
  • A contaminant is highlighted as a darker shade of grey than the product
  • Effective x-ray inspection depends on the sophistication of data analysis

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.

There are some extra requirements needed to install an X-ray inspection system on your food production line which can vary as different states/provinces may have slightly different requirements. First, you will need to ensure your X-ray inspection system is registered with your Department of Health or Office of Emergency Management (for example) prior to using the system. Next, it is the responsibility of the End-User of the x-ray inspection system to ensure proper safety and compliance training (21CFR 1020.40 for Cabinet X-ray systems) is provided to their staff in accordance to state or provincial regulatory agencies. Loma Systems has developed a training course, given by one of our trained Radiation Safety Officers (RSO) to help guide you in the process and show best practices when it comes to registration and training of your operators.

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.