Graduation date: 2003

Approved for public release; distribution is unlimited. / Considering the ever-rising threat of terrorist attack and disruption of the economy and of daily activity, the potential strength of a radiological dispersion device must be evaluated. A "dirty bomb" is a weapon in the terrorist arsenal that is highly effective in creating chaos, panic and disruption. All of the immediate deaths caused by a "dirty bomb" are due to blast effects, however the public association with radiation and nuclear devices is one of fear and hyperbole. The individuals and agencies that respond to this type of event will have the greatest impact on the general public. By looking at case studies and potential scenarios or exercises the first responder can appreciate the nature of radiation as well as its impact on response. The goal of this paper is to provide first responders with basic information on nuclear physics and expose relevant issues in responding to a radiological dispersion device. An understandable link between nuclear physics and radiation response does exist. / Ensign, United States Navy

Thesis (M.S. in Applied Physics)--Naval Postgraduate School, June 2004. / Thesis advisor(s): Xavier Maruyama. Includes bibliographical references (p. 71-77, 79-81). Also available online.

The National Council of Radiation Protection and Measurements Report No. 49, originally issued on September 15, 1976, has been the primary design guide for diagnostic x-ray structural shielding in the United States. To further protect the public from various areas of medical radiation exposure, NCRP issued Report 116 in 1987 to decrease the public exposure limits. These new limits used in conjunction with NCRP 49 to determine shielding requirements for diagnostic radiological rooms can be shown to over-shield based on current technologies and protocols. This paper explores the NCRP conservative assumptions that physicists specifying barrier requirements for diagnostic x-ray facilities normally utilize. These evaluated assumptions, which are incorporated in the methodology and attenuation data presented in NCRP Report 49 formulas, include relatively high single kVp's, a "one size fits all" workload default, and the lack of attenuation factors by the patient, the wall, and the film. In essence, an analysis of the conservative nature of NCRP 49 is demonstrated. An example of Primary and Secondary Shielding Methodology utilizing NCRP 49 and NCRP 116 dose limits is provided as well as the cost factors associated with the results. These examples are further evaluated using a Monte Carlo software program. In addition, an analysis of actual current radiographic conditions in an imaging room is performed. This is done to determine first, the actual mA utilized for specific exams; secondly, the actual mA-min weekly workload; and thirdly, the tangible exams performed per week in small and large medical facilities. Based on the information and analysis presented, this paper concludes that the formulas for NCRP 49 and NCRP 116 need to be reexamined. Furthermore, this paper also demonstrates once again that NCRP 49, utilizing NCRP 116 dose limits is extremely conservative. / Graduation date: 2004