X-ray Screening Technology Safety Reports
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Overview
TSA’s mission is to keep the traveling public safe and that is done by deploying multiple layers of security, including the best available technology, to detect and disrupt possible attacks before they occur. An important part of this strategy is ensuring that the technology used meets safety standards for all travelers and employees while detecting threat items.
Over the nine years since the agency’s inception, TSA has implemented stringent safety protocols to ensure that technology used at airports to screen people and property is safe for all passengers, as well as the TSA workforce.
In addition to regular maintenance, each individual machine that uses X-ray technology is regularly tested to ensure the radiation emitted falls within the national safety standards. The testing is conducted by manufacturers and/or third party maintenance providers, per the terms of their TSA contracts. Contract requirements mandate that the manufacturer notify TSA and the Food and Drug Administration (FDA) should any equipment appear to emit radiation at levels above the national standard. In the event that a radiation test for any technology were to reveal that the emission was above the standard, the machine would be taken out of service and repaired. The backscatter technology in use at airports is designed to be physically incapable of producing the amount of energy needed to emit radiation above the national standard in a single scan.
In the spirit of transparency, TSA is posting reports for all radiation tests, including the annual TSA-mandated test of every X-ray based technology, on www.tsa.gov as they are completed.
Technology Safety Process
Since TSA’s establishment, stringent safety protocols have been developed and implemented to ensure technology is safe for all passengers. This process begins prior to TSA’s decision to use a new technology and continues throughout the life of each individual unit deployed in airports.
For radiation safety, TSA issues procurement specifications that require all manufacturers to comply with nationally-recognized safety standards to ensure the safety of all passengers – including special populations like children, the elderly, and pregnant women – and operators during equipment usage. That means TSA will not begin to test a new technology or consider deploying it to airports until manufacturers validate the technology’s compliance to the relevant safety standards.
The X-ray based technologies TSA deploys are required to be in compliance with national standards. For a number of systems, TSA has performed additional independent third-party testing to further validate compliance with these safety standards.
Backscatter imaging technology units are required to comply with the national standard and the machines are designed to be physically incapable of producing the amount of energy needed to emit radiation above the standard in a single screening Like the protection a circuit breaker provides to a home, the machines contain safety systems that prevent the production of radiation levels in excess of established limits.
After TSA makes an operational decision to use a technology, manufacturers are then required to perform radiation inspections on each individual unit before it leaves the factory and is shipped to TSA. The manufacturer also must perform a radiation test on each unit once it is installed in the airport.
After installation, TSA requires manufacturers and/or maintenance contractors perform periodic radiation tests in accordance with the applicable standards – this happens at least every 12 months.
Additionally, radiation tests are performed after any maintenance that could impact the X-ray sources, emissions or containment and if the unit is ever relocated from its initial installation position. At any time, TSA employees may also request a radiation test.
By conducting ongoing radiation inspection surveys throughout the useful life of the technology, TSA is going beyond regulatory safety standards to ensure passengers and operators are not being exposed to excessive X-ray radiation doses.
Third Party Testing and Analysis
Independent certified health physicists at the U.S. Army Public Health Command (Provisional) perform radiation surveys and inspections on carry-on luggage and checked baggage systems, as well as personal radiation dosimetry studies on TSA security officers. To date, the results of these studies and inspections reveal that TSA systems comply with all applicable standards for emission limits, and that radiation doses to TSA employees are well below the federal dose limits.
Backscatter technology has also been evaluated by numerous third party health experts including the Food and Drug Administration’s (FDA) Center for Devices and Radiological Health (CDRH), the National Institute of Standards and Technology (NIST), and the Johns Hopkins University Applied Physics Laboratory (APL).
Radiation Testing Review
To verify these safety procedures, TSA recently conducted a review of the reports generated from manufacturer and third party maintenance provider radiation testing. Fifteen airports of varying sizes were selected and the last two years of radiation reports were reviewed for a sample of the X-ray based technologies we use in airports. TSA also reviewed the reports for every backscatter advanced imaging technology unit. The other technologies include multi-view advanced technology X-ray units, explosive detection systems, and single projection X-ray systems. The reports confirm that each piece of technology included in the review operated well-within applicable national safety standards when the testing occurred.
Due to public interest in security technology, and TSA’s commitment to transparency and safety, TSA is posting original reports on www.tsa.gov.
Evaluation of Contractor Testing Procedures
These reports confirm that each piece of technology reviewed meets all national safety standards. However, during TSA’s review of these reports, inaccuracies were identified in contractor reporting that affected the documentation of some of the test results. These inaccuracies included:
- Lack of notation for the latest calibration date for the machine being tested or the most recent calibration date noted had expired on survey meters
- Information missing regarding warning labels and required labels
- Calculation errors not impacting safety
- Missing survey point readings
- Inconsistent responses to survey questions
- No reading of background radiation noted
- Missing other non-measurement related information
TSA took immediate action to hold contractors accountable, including directing the contractors to re-test each backscatter imaging technology unit, as well as re-testing any other unit with an inaccurate report, by the end of March 2011.
Improvement Measures
TSA is taking immediate steps to build on the already robust safety protocols in place in an open and transparent way. Administrator Pistole has directed TSA to commission an independent entity to evaluate these protocols. Additionally, TSA is:
- Requiring re-testing of all backscatter advanced imaging technology units in airports, as well as all technology with inaccurate reports, by the end of March 2011;
- Requiring contractors to re-train personnel involved in conducting and overseeing the radiation survey process;
- Requesting the National Institute for Occupational Safety and Health (NIOSH) re-evaluate TSA’s safety program and update its 2008 report;
- Expanding an existing partnership with the U.S. Army Public Health Command to conduct additional independent radiation surveys and radiation safety compliance audits at airports equipped with X-ray based technologies;
- Increasing TSA oversight on the overall radiation survey and documentation process; and
- Ensuring all appropriate contractual remedies are considered and implemented, as necessary, in the event that radiation inspections are incomplete or delinquent.
To provide additional transparency, reports for all surveys currently being conducted and all future radiation survey reports will be posted on www.tsa.gov after they are completed.
By the Numbers
- One year of naturally occurring background radiation: 300 millirem
- Annual recommended limit to the public of radiation from man-made sources: 100 millirem
- Chest X-ray: 10 millirem
- Flight from New York to Los Angeles: 4 millirem
- One day of natural background: approximately 1 millirem
- Drinking three glasses of water a day for a year: 0.045 millirem
- One backscatter X-ray screening: approximately 0.005 millirem
Source: Radiation dose comparisons from the Health Physics Society (http://hps.org/documents/WholeBodyScanners.pdf
(hps.org)) and other safety experts (http://www.cbsnews.com/2300-204_162-10005685-3.html (cbsnews.com)).
Additional Information
For more information on AIT safety, visit: http://www.tsa.gov/research/reading/index.shtm.
Reports
Click here For U.S. Army Public Health Command surveys of backscatter imaging technology and cabinet X-ray systems.
Click here for surveys of checked and carry-on baggage screening equipment.
Click here for surveys of backscatter imaging technology machines.
Click here for U.S. Army Public Health Command Dosimetry Study.
Due to the nature of these redacted documents they may not be fully Section 508 compliant.
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