Since the attempted bombing of an aeroplane bound for the United States on Christmas Day 2009, several countries have made or are in the process of making a decision about mandatory use of full body scanners at airports. “Full body scanners” or “whole body scanners” can be classified as either “millimetre radio wave” or “backscatter” technologies.

Millimetre radio wave systems scan travellers by bombarding them with radio waves and collecting the reflected radio waves via antennae to generate an image.1 This technology does not use x rays. In contrast, backscatter systems use low intensity x rays to scan the body. The x rays do not penetrate the body but bounce off the skin, and are then captured by detectors to create images. These x rays are useful for detecting objects hidden under clothing and taped on the skin but not for detecting objects hidden inside the body.2 For this, transmission x ray systems are needed.2 The table⇓ lists the doses of radiation produced by backscatter systems and the number of backscatter scans needed to yield …