There is considerable uncertainty in the effective dose from Compton backscatter screening systems. The value of 0.1 μSv that Mehta and Smith-Bindman1 used is taken from the limit to effective dose per scan set in the 2002 version of the NS 43.17 standard.2 Because a screening involves 2 scans, the effective dose per screening is 0.2 μSv. In the 2009 revision to NS 43.17, the limit for the effective dose per screening was increased to 0.25 μSv.3 On this basis, the estimates of the number of cases by Mehta and Smith-Bindman1 should be at least 12 per year.
Rez P. Uncertainties in the Dose From Full-Body Airport Screening. Arch Intern Med. 2011;171(12):1129-1130. doi:10.1001/archinternmed.2011.258