In vivo EPR for dosimetry

Abstract

As a result of terrorism, accident, or war, populations potentially can be exposed to doses of ionizing radiation that could cause direct clinical effects within days or weeks. There is a critical need to determine the magnitude of the exposure to individuals so that those with significant risk have appropriate procedures initiated immediately, while those without a significant probability of acute effects can be reassured and removed from the need for further consideration in the medical/emergency system. In many of the plausible scenarios there is an urgent need to make the determination very soon after the event and while the subject is still present. In vivo EPR measurements of radiation-induced changes in the enamel of teeth is a method, perhaps the only such method, which can differentiate among doses sufficiently for classifying individuals into categories for treatment with sufficient accuracy to facilitate decisions on medical treatment. In its current state, the in vivo EPR dosimeter can provide estimates of absorbed dose with an error approximately +/- 50 cGy over the range of interest for acute biological effects of radiation, assuming repeated measurements of the tooth in the mouth of the subject. The time required for acquisition, the lower limit, and the precision are expected to improve, with improvements in the resonator and the algorithm for acquiring and calculating the dose. The magnet system that is currently used, while potentially deployable, is somewhat large and heavy, requiring that it be mounted on a small truck or trailer. Several smaller magnets, including an intraoral magnet are under development, which would extend the ease of use of this technique.

Retrospective and emergency dosimetry in response to radiological incidents and nuclear mass-casualty events: A review

“…∼2 Gy (or a range 0.5-10 Gy) for emergency dosimetry and much lower levels of dose for retrospective dosimetry. Other similar but slightly different definitions may be used elsewhere (e.g., Swartz et al, 2007 andAinsbury et al, 2011).…”

“…While molar, pre-molar and canine teeth are all potential targets for in vivo dosimetry, practical developments have focused on incisors. Developments in both technique and equipment have been described in several summary documents (e.g., Swartz et al, 2007and Sirota et al, 2013Ivannikov et al, 2016;Guo et al, 2016 andSchreiber et al, 2016). Demidenko et al (2007) examined the standard error induced by state-of-the-art in vivo (in 2007) measurements using ex vivo irradiated teeth placed in the mouth of a volunteer in a gap in the dentition.…”

“…Ex vivo X-band dosimetry has developed sufficiently to the point that a typical minimum measureable dose (MMD) as low as 100 mGy can be achieved (e.g., Wieser, 2012), with claims of MMD lower still in some cases Schauer, 2001 andKhvostunov et al, 2015). In vivo L-band dosimetry can produce sensitivities of around a few hundred mGy to 1 Gy (e.g., Swartz et al, 2007).…”

Biodosimetry versus physical dosimetry for emergency dose assessment following large-scale radiological exposures

“…The material examined can be biological in origin (e.g. teeth, fingernails; Swartz et al, 2007;Trompier et al, 2014) or physical (e.g. components from personal electronics, clothing, etc.…”

A microwave resonator for limiting depth sensitivity for electron paramagnetic resonance spectroscopy of surfaces

“…The EPR signal has been found to be proportional to radiation dosage. [8][9][10] Three body tissues contain the protein keratin: fingernail, toenails, and hair. This work focuses on the fingernails and toenails.…”