Security & Medical X-Ray Differences

TSA uses x-rays to find security threats hidden in suitcases and cargo. Doctors use medical x-rays to detect health threats, such as cavities, broken bones and cancers. Both applications use comparable technology to find hidden dangers. Yet the machines they use are not exactly the same. Ever wondered why that is?

The exact systems used vary depending on what is being scanned and the information you need to get. This post explores the similarities and differences between medical x-rays and security x-rays, helping you better understand each of these tools’ unique value.


X-rays, discovered by Wilhelm Roentgen, are a form of electromagnetic radiation. On the electromagnetic spectrum, these invisible rays fall between gamma rays and ultra violet light (Figure 1). They penetrate materials human eyes cannot see through. And x-rays have short wavelengths and high frequencies. This means that x-rays emit a generous amount of energy – in this case, radiation.
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Figure 1: An illustration of the electromagnetic spectrum showing comparison between wavelength, frequency and energy. (Image Credit: NASA)

There are two types of radiation: non-ionizing and ionizing. Non-ionizing radiation does not have enough energy to ionize atoms or molecules. Thus there are no adverse health effects associated with it. Ionizing radiation, found in x-rays, has enough energy to remove electrons from their orbit around an atom. Losing electrons in this way causes the atom to become charged or ionized. Because of this, ionizing radiation poses health risks and concerns. The radiation can potentially damage DNA and may increase people’s risk of developing cancer.

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(Figure 2): The electromagnetic spectrum showing ionizing and non-ionizing radiation. (Image Credit: Wikipedia)
Yet when handled and used properly, X-rays have many safe and useful applications. As we will see in the following sections, x-rays are more helpful than harmful when it comes to protecting your health and safety.


In medicine, x-ray imaging exams are valuable tools used for many examinations and procedures. Doctors can non-invasively and painlessly diagnose diseases and prepare for surgeries. X-rays also help medical professionals insert stents, catheters, or other devices into patients. Inserted safely, these tools help treat tumors, blood clots, or other threats to patients’ health.
There are a few types of medical x-rays that use ionizing radiation:
Radiography: A single x-ray image recorded for later evaluation (e.g. dental x-rays).
Fluoroscopy: A continuous x-ray image displayed on a monitor. This allows for real-time monitoring of procedures or passage of contract agents (“dyes”) through the body.
Computed Tomography (CT): A detector moves around the patient’s body recording x-ray images. Computers then reconstruct the individual scans into cross-sectional images (“slices”) showing internal organs and tissues.

During these non-invasive procedures, an x-ray beam passes through the patient’s body. Some of the X-rays are absorbed or scattered by the internal structures (bones, tissues, etc.). Detectors capture any remaining x-ray pattern, and computers process the pattern into images doctor can review. The capabilities and radiation exposures involved in medical x-rays differs depending upon the type of scan used. A visit to the dentist may involve x-rays of your teeth. Dental x-rays are a type of radiography imaging. They allow dentists to see the condition of their patients’ teeth from the crown to the roots. During the scan, x-rays pass through the cheek, gums, and teeth and strike a special x-ray film clamped between the teeth. That film is then processed and analyzed by the dentist for cavities. In some cases, patients wear a lead apron to prevent radiation exposure to other parts of their bodies. However, the amount of radiation exposure from a dental x-ray is so small a lead apron often isn’t necessary.


Figure 3: The Aquilion ONE CT scanner by Toshiba has a rotational speed of up to 0.275 seconds. (Image Credit: Toshiba)

CT scan radiation exposure though can be several hundred times greater than conventional medical x-rays. This is because the detailed slices can only be obtained through longer x-ray exposures. During the procedure, the patient lies on a table that slides into the CT scanner – a large machine with a hole in the center. The x-ray tube and electronic detectors rotate around the patient capturing x-ray images. A separate control room then processes the images and generates detailed slices for doctors to review. Despite the increased radiation exposure, CT scans are often the best method for detecting threats like cancer. Their detailed image slices allow doctors to confirm a tumor’s presence, size, and precise location. Doctors can also determine whether a tumor is affecting or connected to other nearby tissues.

Medical x-rays are a very powerful healthcare tool. They can provide important life-saving information, are non-invasive and also painless. The images produced reveal internal structures hidden by skin and bones. They carry the risk of some radiation exposure, but the potential benefits outweigh those limited risks.


Ever since 9/11, governments around the world have worked to improve air travel security. Visual inspections may be enough when checking small items. Large items though, like luggage and shipping crates, need more thorough searches. X-ray imaging security is ideal for searching items without opening and manually inspecting each one. The tools are quick and reliable, and produce detailed images showing what’s inside each scanned object.
X-ray security scanning isn’t limited to only airports. Scanners can vary in size from parcel scanners to large vehicle and cargo scanners. They serve numerous markets including law enforcement, transportation, critical infrastructure, and the military. Finding the right x-ray security system can be a simple process. The end user simply needs to know what objects they will be scanning and what they are looking for.

There are two (2) common types of x-ray security scanners:
Cabinet x-ray Systems: Contain an x-ray tube installed within a shielded enclosure. The enclosure is made up of a material, usually lead, that prevents most of the x-ray radiation from escaping the cabinet.
Personnel Security Screening Systems: Two types of people screening electronic products used by TSA to screen people at airports are General Use X-Ray Screening Systems & Millimeter Wave Security Screening Systems

Cabinet x-ray systems are very common inside airports, courthouses and at border crossing stations. Some uses for these systems include screening baggage, inspecting trucks crossing borders, and food inspections. Cabinet x-ray systems make it possible to inspect the contents of parcels, boxes and luggage without damaging the contents inside.


Figure 4: Cruise ship passengers line up at a port in Denmark for a routine security screening before boarding the cruise ship. (Image Credit: Astrophysics Inc.)

General use x-ray screening systems deliver low doses of ionizing radiation. These systems are also known as “backscatter” systems because they create images from the small amounts of x-rays that bounce off the screened individual. The reflected x-rays are detected and processed by computers to form an image for operators to review.


Figure 5: A TSA officer screens a woman with a millimeter wave machine at an airport security checkpoint. (Image Credit: Reuters)

Millimeter wave security screening systems use non-ionizing radiation and come in 2 forms. The first are active systems that expose the screened person to small amounts of millimeter wave energy. The second are passive systems that detect naturally occurring millimeter wave emissions from bodies. These machines use radio frequency waves to detect threats and they emit thousands of times less energy than a cell phone.
In today’s world it is not uncommon to screen items and people before allowing them access to a secure area. Airports, courthouses, prisons, and businesses use x-ray screening systems to detect concealed weapons, explosives, and other contraband. They provide security personnel with detailed images and don’t require physical inspections. The radiation emitted from these products is very minimal and does not pose any risk to the screened individual or items.


Medical x-rays and security scanners share many similarities. They both use radiation to non-intrusively detect hidden threats. But there are key differences as well. For example, medical x-rays are considered more dangerous because of their longer exposure times. A patient getting a CT scan receives far more radiation than a traveler passing through airport security. Thus, medical professionals must be trained in safe x-ray scanning procedures.

Medical professionals need x-ray training for another reason – they review every scan themselves. Security x-rays include various automation and inspection features that help operators locate hidden threats. Doctors must diagnose injuries and diseases while reviewing scans with their own 2 eyes.
Security screening doesn’t need that same professional supervision that medical screening does, but when scanning hundreds or thousands of items every day, x-ray security screening must be efficient and quick to process. Automated software within the machines make it possible to scan and detect suspicious materials without lengthy manual inspections.


Figure 6: An example of a medical x-ray in black and white. (Image Credit: Nevit Dilmen/Wikipedia)

In terms of software, the differences are black and white – literally! Medical x-rays produce black and white images for doctors to review. These x-rays only have to penetrate through skin, bone and water, so there is no need for them to show color. Doctors are looking for small threats inside the body, so detailed shades of grey better help them locate these issues.
Security x-rays can be either black and white or in color. The different colors displayed on the x-ray image are determined by the atomic number of the materials scanned. This helps operators differentiate between the types of materials inside a scanned item – metals, liquids, powders, plastics, etc. Security operators can often see all the objects within a scan. Their challenge is determining what it is they’re looking at, and color imaging better helps them do that.

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Figure 7: Luggage is put through an Astrophysics Inc. x-ray scanner. The image assigns colors to scanned objects based on the objects’ atomic numbers. (Image Credit: Astrophysics Inc.)

If you want to learn more about radiation emitting products in both medicine and security, visit the U.S. Food & Drug Administration website. The U.S. Environmental Protection Agency also has materials available to help you learn about radiation in your town. Lastly, be sure to visit the Astrophysics, Inc. blog to read about our products, latest company news and thought-provoking articles on x-ray security technology.

Astrophysics, Inc. makes hidden threats visible. We manufacture leading x-ray security scanners and offer cutting-edge imaging for any application and budget. Operators in over 150 countries use our advanced system features, including 6-Color Imaging and Picture Perfect functionality, to detect threats and contraband hidden within everything from suitcases to cargo containers. Astrophysics, Inc. units adhere to rigorous industry specifications, and we offer TSA- and ECAC-qualified scanners for any security mission. Follow us on Twitter, LinkedIn, Facebook and YouTube for the latest news and x-ray product updates.

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