Optimizing Bomb Squad X-Ray Systems for Incidental Human Exposures
C Hill1*, I Rutel2, F Cain3, (1) ,,,(2) University of Oklahoma Health Science Center, Oklahoma City, OK, (3) Edmond Police Department, Edmond, OKSU-E-I-105 Sunday 3:00:00 PM - 6:00:00 PM Room: Exhibit Hall
Purpose: A current terrorist tactic involves strapping an explosive device to a live victim. Technicians wishing to x-ray the device need to use appropriate exposures to create clear images while mitigating incidental health problems for the live victim. This project involves characterizing and optimizing a popular radiographic system in the explosive investigation community, both for general use and, more specifically, for generating x-rays with a human subject in the beam path. This project seeks to minimize the dose to a victim incidentally located in the beam path, while maximizing image quality, thereby allowing appropriate image evaluation to neutralize the explosive threat.
Methods: Image quality and dose optimization begins with characterization of the x-ray source. The source in this study is an XRS-3, a portable device developed by Golden Engineering, which nominally produces a 270 kVp beam. Characterization of the beam involves verifying the actual kVp, as well as determining the average energy of the beam with various amounts of filtration added to the beam path. The kVp was verified using a noninvasive technique, utilizing the measurement of the dose attenuation through lead and then modeling the energy dependent attenuation curve of the lead using specific mass attenuation coefficients and parameters suggested by Joseph (Joseph, P.M., Med. Phys. Vol. 2, July/Aug 1975; 201-207) in order to calculate the kVp through linear regression.
Results: The average energy of an unfiltered beam was 52 keV, and increases through adding various combinations of Cu and brass filters to a maximum value of 121 keV with 3 mm copper + 3 mm brass filtration. The calculated kVp was 290 kV.
Conclusions: The average energies using filtration fall within the diagnostic range. The kVp fits well within the manufacturer's specifications of 15% deviation. Optimization can be accomplished with these parameters.