Computer users carrying laptop computers and digital media aboard aircraft are frequently concerned about possible deleterious effects of airport x-ray baggage scanning devices. Such concern is intensified by the warning "Magnetic Material--Do Not X-RAY" stamped on software packages arriving by mail.
A simple experiment consisting of exposing 3½" floppy disks to various x-ray techniques was therefore undertaken to test the effects of radiation on digital media.
Methods and Materials
Thirteen identical 3½" floppy disks were formatted and loaded with
several small files including text, graphics, and applications. All
disks and programs were verified to be error-free prior to the
experiment.
The first disk was exposed to two minutes of fluoroscopy and three "spot film" exposures, with technique as might be used during a gastrointestinal (GI) study. This sequence of radiation was chosen to simulate multiple passages through a typical airport x-ray unit used for scanning hand-carried baggage.
Seven disks were radiographed in our Radiology Department according to the techniques given in Table 1. The energy of the x-rays (kv) and exposures (mas) were therefore different for each disk but comparable to what a patient might expect to receive during routine diagnostic studies. An additional disk was exposed for 30 minutes to gamma rays from a syringe containing 20 mci 99m-Technetium pertechnetate.
Two disks placed inside carry-on baggage were radiographed twice by an airport x-ray scanner prior to a domestic flight. No special precautions were taken. One disk, carried inside a shirt pocket, passed through a metal detector twice without incident.
The final disk served as a control.
Results
Without exception, each disk was verified to be free of error
following x-radiation and all programs performed flawlessly regardless of
the x-ray source or the technique used. The disks passing through the
metal detector was also unchanged.
Disks were re-checked one year later to exclude the possibility of accelerated deterioration.
Discussion
The simple experiment described here suggests that with occasional
x-ray exposures that one may encounter in U.S. airports and in diagnostic
Radiology departments, there is no discernible short or long term effect
on floppy disks or their data. Although portable computers were not
tested here, we would note that a desktop computer used in our Nuclear
Medicine "hot lab" has functioned without problem for more than five
years.
Our findings would tend to support the written claim of EG&G Astrophysics Research Corporation, Long Beach, California, a supplier of x-ray scanner units and metal detectors, that:
They proceed to cite the American Society for Testing and Materials (ASTM) in their Standard F792-88 which states in paragraph 7.11:
Conclusion
At the present time, there is no evidence that domestic airport x-
ray scanners used to examine carry-on baggage causes damage to digital
media. An interesting article by Bud Sadler entitled "X-Rays Ate My
Data: An Airport Security Myth" (Portable Computer Review, Vol.2(2),
1988, pp. 8-12) may be read for further information.
The present study did not include the possibility of higher radiation exposures that may be in effect at some European and Asian airports. We also acknowledge the possibility that removable media such as Syquest (TM) or Bernoulli (TM) disks may be better models for hard drives in current portable computers, but the functioning of large quantities of data on them would be more difficult to verify. Finally, we did not directly consider mechanical stability or magnetic fields from scanner units and other electronic equipment, although these variables were certainly present in those disks carried through the airport.
Perhaps the best recommendation is the one regarding frequent and multiple back-ups of important files. Although, carrying data on a CD ROM might address many of the issues discussed in this study, it would not avoid the possibility of loss or theft which may be more serious threats.
Archived ("backed-up") data which can be quickly accessed from home or office via courier, modem, Internet, or Intranet give piece of mind not otherwise easily obtainable.
July, 1996
| Kilovolts (kv) | Milliampere-seconds (mas) | Diagnostic Study |
|---|---|---|
| 100 | 5 | Chest x-ray |
| 70 | 40 | Pelvis |
| 70 | 8 | Pelvis (Table) |
Michael Tobin, M.D., Ph.D.
Department of Radiology
Metropolitan Hospital Center
1901 First Avenue
New York, NY 10029
Perry Gerrard
Department of Radiology
Maimonides Medical Center
4802 Tenth Avenue
Brooklyn, New York 11219