Marquette University

Department of Biomedical Engineering


This statement is in regards to the paper by Michael E. Hoppe and Taly Gilat Schmidt on "Estimation of organ and effective dose due to Compton backscatter security scans," published in the June issue of Medical Physics .

Our study on backscatter airport scanners did not quantify the risk of the scanners nor did it draw any conclusions about risk.

The purpose of the study was to estimate, through computer simulations, the radiation dose deposited in organs during backscatter security scans. As stated in the published, peer-reviewed paper, "Access to the machines for measurements and assessments is limited." Therefore our models were based on exposure measurements previously obtained by the Johns Hopkins Applied Physics Laboratory, in a study commissioned by the TSA. This limitation is prominently discussed in our paper.

The overall conclusion of the paper is, "Backscatter security scanners deposit dose in organs beyond the skin. The effective dose is below recommended standards set by the Health Physics Society (HPS) and the American National Standards Institute (ANSI) assuming the system provides a maximum exposure of approximately 4.6 microR at 30 cm.'' The paper concludes by stating, "However, as with all imaging modalities using ionizing radiation, the risk must be weighed against the benefit, both of which must be quantified for backscatter security scans."

We hope that this work will lead to more independent studies on the radiation, safety, and efficacy of these scanners. Our paper also states that, "Public disclosure of the systems' specifications would enable more accurate system modeling." Thus, the published paper is just one step in understanding the performance of these systems.

For more information:

WUWM Lake Effect podcast, CNN article, Chicago Tribune

Statement on Airport Scanners