Estimation of organ and effective dose due to Compton backscatter security scans. Med Phys 2012 Jun;39(6):3396-403
Date
07/05/2012Pubmed ID
22755720DOI
10.1118/1.4718680Scopus ID
2-s2.0-84863522496 (requires institutional sign-in at Scopus site) 7 CitationsAbstract
PURPOSE: To estimate organ and effective radiation doses due to backscatter security scanners using Monte Carlo simulations and a voxelized phantom set.
METHODS: Voxelized phantoms of male and female adults and children were used with the GEANT4 toolkit to simulate a backscatter security scan. The backscatter system was modeled based on specifications available in the literature. The simulations modeled a 50 kVp spectrum with 1.0 mm-aluminum-equivalent filtration and a previously measured exposure of approximately 4.6 μR at 30 cm from the source. Photons and secondary interactions were tracked from the source until they reached zero kinetic energy or exited from the simulation's boundaries. The energy deposited in the phantoms' respective organs was tallied and used to calculate total organ dose and total effective dose for frontal, rear, and full scans with subjects located 30 and 75 cm from the source.
RESULTS: For a full screen, all phantoms' total effective doses were below the established 0.25 μSv standard, with an estimated maximum total effective dose of 0.07 μSv for full screen of a male child. The estimated maximum organ dose due to a full screen was 1.03 μGy, deposited in the adipose tissue of the male child phantom when located 30 cm from the source. All organ dose estimates had a coefficient of variation of less than 3% for a frontal scan and less than 11% for a rear scan.
CONCLUSIONS: 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 μR at 30 cm.
Author List
Hoppe ME, Schmidt TGAuthor
Taly Gilat-Schmidt PhD Associate Professor of Biomedical Engineering in the Biomedical Engineering department at Marquette UniversityMESH terms used to index this publication - Major topics in bold
AdultChild
Dose-Response Relationship, Radiation
Female
Humans
Male
Monte Carlo Method
Phantoms, Imaging
Radiation Dosage
Scattering, Radiation
Security Measures
