Virtual Imaging: versatile detection at low radiation dosage


  • the machine must be versatile, able to detect a wide variety of materials
  • the radiation dose required must be low enough so as not to pose health risks for the individuals being screened

Virtual Imaging says RadPRO SecurPASS meets these criteria. It is able to scan for all kinds of materials, making it suitable for airports, prisons, border crossings, and government buildings. The technology allows security personnel to detect both metallic and non-metallic, organic and inorganic items minimize the need for physical searches; enhance privacy by not revealing skin surface or fine anatomical detail; and do all this while using very low radiation dosage for single inspection.

RadPRO SecurPASS and radiation doses

The growing use of full-body scanners at airports — but also at courts, government buildings, sport events, concerts, and more — has caused concerns about the amount of radiation to which passengers are exposed. The same questions may be directed at RadPRO SecurPASS, which uses X-ray radiation for detection purposes.


A few months ago (“RadPRO SecurPASS from Virtual Imaging,” 16 June 2010 HSNW) we wrote that the patented technology behind its RadPRO SecurPASS meets the low-radiation requirement.

Radiation is measured in microsievert (μSv):

  • μSv = 0.01 mrem, so that 10 μSv = 1 mrem
  • mSv = 1,000 uSv = 100 mrem, so that 100 mSv = 10 rem

The National Council on Radiation Protection and Measurements (NCRP) has been asked by the Food and Drug Administration (FDA) to prepare a report on radiation and safety. NCRP has adopted measurements developed by the American National Standards Institute (ANSI), which has approved a standard for scanning systems using X rays. NCRP and ANSI recommended that the effective dose per scan should be 0.1 μSv or less.


NCRP, for the purpose of radiation protection, recommended that:<

  • There should be two categories of ionizing radiation devices used for scanning humans for security screening purposes, general-use systems and limited-use systems.
  • An effective dose of 0.1 μSv (or less) per scan is the basic criterion for distinguishing between the two categories. Both categories of systems should meet the recommended administrative control for a member of the public of 0.25 mSv (or less) effective dose per year for a single source or set of sources under one control (typically, “under one control” would refer to the use of scanning systems at one or more security checkpoints at a given venue)

General-use systems. General-use systems would be used mostly without regard to the number of individuals scanned or the number of scans per individual in a year, and should adhere to an effective dose of 0.1 μSv or less per scan. These systems would be appropriate for screening all members of the general public passing through a checkpoint, provided that the implementing agency has established the justification for such a screening procedure. The checkpoint in question is generally a security venue, and no attempt would be made (for the purpose of radiation protection) to limit the screening only to a selected portion of those seeking passage.


Limited-use systems. Limited-use systems would be used with discretion in terms of the number of individuals scanned and the number of scans per individual in a year, and would include all ionizing radiation scanning systems that require effective doses per scan greater than 0.1 μSv and less than or equal to 10 μSv per scan. At 10 μSv per scan, an effective dose of 0.25 mSv would be reached after only 25 scans.

These systems include scanning devices that exceed an effective dose of 0.1 μSv per scan, but the scanning device should not exceed 10 μSv per scan. In addition, the total effective dose for any individual should be 0.25 mSv or less in a year from limited-use systems used at a single venue.

The company says that the dose a scanned individual is exposed to when scanned by SecurPASS is less than 0.25 μSv per scan. Here are some effective radiation dosage comparisons. According to the American College of Radiology, the accepted and agreed to exposure that a person would receive from a standard chest X-Ray-AP/LAT is 100 uSv. A person would have to be scanned on the RadPRO SecurPASS System 400 times to equal the dose received from one chest X-Ray study. The radiation dosage one is exposed to by one scan by the SecurePass (I removed LD) is thus similar to the following:

  • 30 minutes of exposure to naturally occurring background radiation in Cornwall in the United Kingdom or Denver, Colorado = 0.25 μSv
  • 4g of Brazil nuts = 0.25 μSv
  • 3 minutes during a commercial flight at 30,000 feet = 0.25 uSv.