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Sample Project: After-the-Fact Dosimetry Device—Unplanned Radiation Exposure

Overview

Electron paramagnetic resonance (EPR) has been used for more than 40 years for measurements of exposure to radiation, including dating applications in fields like geology and archeology. Most importantly, dosimetry has been used retrospectively to assess the exposure to radiation of the victims and survivors of the atomic bombs in Japan and, more recently, the Chernobyl accident. The use of EPR is based on its unique capabilities to measure free radicals.

Teeth have traditionally been used for this type of test because this matrix material (especially that of the enamel) stabilizes the free radicals created during exposure to radiation. The amount of free radicals present in the matrix is therefore proportional to the dose of radiation received.

Traditionally, tests have been conducted by making measurements on teeth that have been shed due to natural causes or treatment, and then concentrating the enamel material to make the measurements using conventional EPR spectrometers. However, with the advent of new EPR techniques that permit the measurements to be made in living subjects, dosimetry measurements can be conducted in vivo, without removal of the teeth. With this advancement, such technology can be used to help deal with the medical consequences of a nuclear catastrophe when a population of people is exposed to an unknown amount of radiation. In such an event, it is important to be able quickly and reliably to triage people into three categories:

Group 1: Low radiation exposure and low risk of becoming sick. It is important to define this group (the largest) to help keep the system clear for those actually in need of medical attention (<~2 Gy).
Group 2: Moderate radiation exposure that carries significant risk but can be treated (~2<~7 Gy).
Group 3: Those who have received a dose of radiation that is probably too high to respond satisfactorily to medical intervention (>~7Gy).

We have been developing a prototype and a set of clinical trials using this technology over the past 15 years. The need for such a capability is indicated by the fact that this development is being supported by grants from NIH and the Department of Defense. The overall orientation of the research is to develop a device that is transportable and readily operated in the field with sufficient speed and accuracy that large numbers of people can be screened by first responders. The current device focuses on making the measurements in the molar teeth (the large teeth in the back of the mouth). Recent developments have indicated that there may be some significant advantages in making the measurements on the back of the incisors (the front teeth).

We are looking for help to develop the technical aspects of this new approach. The current process takes ~15 minutes, uses the molar teeth for analysis, and is largely comprised of setup time. It also is limited by the fact that many people have extensive fillings in their molar teeth, making it difficult to find sites where the enamel can be measured. The time required for the measurements could be drastically reduced and allow for a more rapid triage system in the event of an emergency if there existed a method to create and position the resonator loop on the teeth in the front of the mouth (the incisors). The general feasibility of this approach has been demonstrated, but an effective and practical device to make the measurements needs to be developed. The requirements are both in the development of the hardware to position the loop and also in modeling to determine the optimum configuration of the sensing end of the detector.

Goals

Create device to position the measuring/holding detector (resonator) on the back of the incisor teeth in a way that is rapid, reproducible, and comfortable for the subject.
Create a program that uses finite element analysis to evaluate different configurations of the sensing resonator loop that provides maximum sensitivity and ease of placement.

Deliverables

Design and then carry out finite element analysis to determine the loop shape(s) that gives maximum sensitivity. The potential variables involve the size and shape of the sensing loop, the location of the enamel in the teeth, and the distribution of the electromagnetic field in the loop.
Design and then fabricate a device for reliably positioning the resonator on the back of the incisors.
Define procedures for operation of the device by non-technical, non-trained staff.
Recommend portability related enhancements.

Required Facilities

Our laboratory is considered to be the leading site in the world for the development of in vivo EPR and for in vivo EPR dosimetry. The instruments used for the measurements are made in the laboratory. Several very skilled and experienced engineers and EPR spectroscopists are involved in the overall project. The idea of using the incisors is a new and promising approach, but because of other aspects that are already underway in the research, it is difficult to allocate sufficient time for these developments to be carried out by the existing staff. They will, however, be fully available to provide advice and feedback to the students undertaking this project. Most or all of the measuring devices are in place as well as facilities for testing the developments in vitro and then in volunteers. If the project is successful the students will be making an important contribution towards meeting a significant national need. They would be authors or co-authors in the papers resulting from these developments. There would be the potential for continuing involvement beyond the time of the 190 project for the continuing development of the technique through the grants that support it and/or a small company that is involved in the commercialization of the technique.

On the other hand this would be a challenging task. While an extensive supporting structure is in place, the students would be expected to provide much of the initiative and hard work to make the actual hardware and to develop the software. The project is of central importance to the overall research so there will be a demand and expectation of high quality and diligent work on the project. There would be an ongoing need for the students to become familiar with the principles and practice of the research and to be involved in the discussions of the overall progress and plans of the overall research. That is, they would be expected to be real members of the team!

Knowledge Areas Needed for Project

Fluid mechanics
Solid mechanics
Machine design
Control systems
Electromagnetics
Materials science
Biomedical engineering
Statics and dynamics
Product design
Engineering graphics (CAD/CAM)

Proprietary Information and Confidentiality Requirements

Confidentiality required for sponsor-provided information
Intellectual property ownership rights retained by sponsor
Sponsor accepts responsibility to discuss IP ownership directly with the student project team and project advisor