All You Need to Know about X-Ray Inspection of Food

Over the last 20 years, food processors have become increasingly reliant on X-ray inspection equipment to identify physical contaminants in production. This is unsurprising, as X-ray inspection equipment has become more sensitive, less expensive, and more reliable. X-ray systems can also be extremely user-friendly.

Nevertheless, some food manufacturers still worry about the safety of X-ray technology—for both the equipment's operators and the food products it inspects.

Ultimately, X-ray inspection of both packaged and bulk food products is known to be very safe. No documented evidence exists to suggest there are adverse health effects of X-rays on those operating equipment, the food products that pass through the equipment, or those who consume the inspected products.

To understand why this is the case, join Thermo Scientific to investigate how modern X-ray inspection equipment works and to rectify any misunderstandings linked to this widely used technology.

X-Ray Technology is Everywhere

Many items used or consumed daily such as food, beverages, medicine, and cosmetics – are inspected using X-ray systems at some point during the manufacturing process, meaning everyone is exposed to products that have been irradiated. The U.S. Food and Drug Administration states no known adverse effects from utilizing products irradiated by such “cabinet-type” X-ray systems.

Food X-ray inspection systems also do not utilize radioactive materials to generate X-ray images, which could be unsafe. Instead, they depend on tubes that electrically produce the X-ray beam. The beam is directed at the object under inspection, while a digital detector on the other side of that object generates an image for analysis.

Unlike using a radioactive source, this system's benefits include the fact that the X-ray energy immediately stops when the tube is switched off.

That being said, food X-ray systems produce ionizing radiation making it important to understand what levels are considered safe, which regulations are applicable, which safety devices are used to meet these regulations, and what can be done during manufacturing and installation to ensure safety across the board.

Everyone is Exposed to Radiation

Everyone is exposed to naturally occurring background radiation. Natural radiation makes up around 50% of the 620 millirems (mrems) of radiation an average person experiences each year, says the United States Nuclear Regulatory Commission. The International Commission on Radiological Protection additionally says that people can absorb 5,000 mrems per year (8X the natural dose) before radiation becomes a health risk.

While food X-ray systems produce radiation during normal use, a worker at the control panel of an X-ray food inspection machine is unlikely to receive any radiation from the machine thanks to shielding.

These machines produce 0.1 mrems per hour or less, and such emissions are usually at the inlet or outlet where workers are not present. Multiplying 0.1 mrems per hour over a 40-hour work week by a 50-week work year would mean that a worker may be exposed to 200 additional mrems each year in the worst-case scenario—significantly under the maximum exposure threshold.

To put X-ray exposure during food production into perspective, below is the average amount of radiation typically received from some common life experiences.

The Trend Toward Lower X-Ray Power and Emissions

Since food X-ray systems were introduced several decades ago, technological improvements have greatly lowered the X-ray power required to inspect food items. Tubes are more efficient, while detectors are more sensitive. This means there is also less X-ray “scatter” inside machines, making protecting workers from radiation leakage easier.

While X-ray equipment from 10 years ago operated in the 300 to 500-watt range, equipment on today’s market generates the same or superior performance from 70 to 150 watts – a 70% reduction in power and emissions. As new detector technology emerges, the power necessary for inspecting food is thought to reduce even more.

Ensuring X-Ray Equipment is Safe

Countries worldwide have regulatory standards to ensure X-ray safety. These regulations ensure that X-ray tools are usable by technicians and operators in all possible conditions. Thermo Scientific^™ X-ray inspection machines are always certified to these standards before selling and installing systems in these regions. Examples of key regulations by country are displayed below.

Source: Thermo Fisher Scientific – Production Process & Analytics

Some of Thermo Fisher Scientific's most critical design and manufacturing guidelines are derived from these regulations.

• A maximum of 1.0 microsievert of radiation can leave the system at a minimum distance of 5 cm from the machine. Note the U.S. FDA limit is 5 microsieverts (.5 Mrem/hr) at 5 cm; the UK IRR 1999 is 1 microsievert at 10 cm, so this test is a worst-case scenario combination of the two standards.
• Interior shielding is utilized from materials like stainless steel and lead to comply with the radiation leakage standard.
• Multiple layers of radiation-blocking curtains are placed where products enter and exit the system.
• Access panels demand a tool to open and feature an electronic interlock. When a panel is opened for cleaning or maintenance, the X-ray source and conveyor switch off immediately.
• When a conveyor belt is stopped to resolve a jam or to address some other production problem, the X-ray should immediately switch off.
• If a problem is identified, an X-ray lockout key switch is included to ensure the system cannot be switched on before repair.
• Warning signs are applied to the in-feed and out-feed apertures to prevent operators from reaching into the machine while the X-rays are underway.
• A warning light tower is included and shows when the X-ray source is switched on. If the warning light becomes non-functional, the system will not permit the X-ray source to be switched on.
• Country-specific labeling in the local language is applied to the machine as needed.
• Every machine is tested for radiation after manufacturing and before shipment. Additional testing is carried out on the customer side when installed.
• All radiation survey records are kept on file at Thermo Fisher Scientific.

Image Credit: Thermo Fisher Scientific – Production Process & Analytics

Thermo Scientific^™ X-ray radiation meter. Image Credit: Thermo Fisher Scientific – Production Process & Analytics

Local Regulations and Best Practices

Although Thermo Fisher Scientific strives to do everything possible to design, build, and install systems according to high safety standards, clients may wish to do other things to comply with local regulations or to ensure employee safety.

For example, some U.S. states and other countries demand annual radiation surveys. Registering X-ray equipment with the appropriate local authority may also be necessary by letting them know the installation location and date. In the United States, the unit’s placement is additionally registered with the Food and Drug Administration. Local governing bodies can also audit equipment performance whenever they feel it to be necessary.

Customers can buy X-ray meters, perform their own X-ray surveys, and record the results. Alternatively, service professionals from Thermo Fisher Scientific can carry out and document a periodic survey on customers’ behalf. Custom designs are available for food processors who desire the extra assurance of additional shielding (or are worried about specific operator risks).

Lastly, Thermo Fisher Scientific’s employees who manufacture X-ray machines always wear a dosimeter for enhanced safety. This device assesses exposure to ionizing radiation. As radiation is not visible or smelled, a dosimeter ensures the equipment always functions properly. Dosimeters can also be ordered and utilized by workers at food production facilities as an additional layer of precaution.

Image Credit: Thermo Fisher Scientific – Production Process & Analytics

Thermo Fisher Installation Safety Checklist

When Thermo Fisher Scientific’s field service technicians install an X-ray inspection system, they will also carry out an on-site radiation survey and record the results. They additionally review the following topics with customers and provide help and answers when required.

Source: Thermo Fisher Scientific – Production Process & Analytics

During installation a service technician should verify the following:
	The facility or company has a radiation safety officer
	There is a plan or process to do radiation surveys at specified time intervals
	Employees have an understanding/knowledge of radiation safety
	Signage is installed properly on and near X-ray equipment
	Emergency medical procedures are posted in the area and are understood
	If dosimeters are requested, employees are wearing them
	Equipment is registered with the state, province, or other local authority

Source: Thermo Fisher Scientific – Production Process & Analytics

Typical registration documentation requirements include:
	Equipment type, model, and specification as a cabinet device per FDA CFR 21 1020.40
	Maximum X-ray voltage and current
	Number of X-ray tubes
	Building location

Conclusion

X-ray inspection of food products has proven safe. Protocols exist to ensure that equipment performs safely after being commissioned and that safe operation can be confirmed at any time to meet plant or regulatory standards.

X-ray inspection improves detection for numerous food applications and is easier to utilize than metal detection technology.

This information has been sourced, reviewed and adapted from materials provided by Thermo Fisher Scientific – Production Process & Analytics.

For more information on this source, please visit Thermo Fisher Scientific – Production Process & Analytics.