Armin Ansari

Educating medical staff about responding to a radiological or nuclear emergency

A growing body of audience research reveals medical personnel in hospitals are unprepared for a large-scale radiological emergency such as a terrorist event involving radioactive or nuclear materials. Also, medical personnel in hospitals lack a basic understanding of radiation principles, as well as diagnostic and treatment guidelines for radiation exposure. Clinicians have indicated that they lack sufficient training on radiological emergency preparedness; they are potentially unwilling to treat patients if those patients are perceived to be radiologically contaminated; and they have major concerns about public panic and overloading of clinical systems. In response to these findings, the Centers for Disease Control and Prevention (CDC) has developed a tool kit for use by hospital medical personnel who may be called on to respond to unintentional or intentional mass-casualty radiological and nuclear events. This tool kit includes clinician fact sheets, a clinician pocket guide, a digital video disc (DVD) of just-in-time basic skills training, a CD-ROM training on mass-casualty management, and a satellite broadcast dealing with medical management of radiological events. CDC training information emphasizes the key role that medical health physicists can play in the education and support of emergency department activities following a radiological or nuclear mass-casualty event.

Using handheld plastic scintillator detectors to triage individuals exposed to a radiological dispersal device

After a radiological dispersal device (RDD) event, people could become internally contaminated by inhaling dispersed radioactive particles. A rapid method to screen individuals who are internally contaminated is desirable. Such initial screening can help in prompt identification of those who are highly contaminated and in prioritising individuals for further and more definitive evaluation such as laboratory testing. The use of handheld plastic scintillators to rapidly screen those exposed to an RDD with gamma-emitting radionuclides was investigated in this study. The Monte Carlo N-Particle transport code was used to model two commercially available plastic scintillation detectors in conjunction with anthropomorphic phantom models to determine the detector response to inhaled radionuclides. Biokinetic models were used to simulate an inhaled radionuclide and its progression through the anthropomorphic phantoms up to 30 d after intake. The objective of the study was to see if internal contamination levels equivalent to 250 mSv committed effective dose equivalent could be detected using these instruments. Five radionuclides were examined: (60)Co, (137)Cs, (192)Ir, (131)I and (241)Am. The results demonstrate that all of the radionuclides except (241)Am could be detected when placing either one of the two plastic scintillator detector systems on the posterior right torso of the contaminated individuals.

Evaluation of internal contamination levels after a radiological dispersal device incident using portal monitors.

Following a radioactive dispersal device (RDD) incident, it may be necessary to evaluate the internal contamination levels of a large number of potentially affected individuals to determine if immediate medical follow-up is necessary. Since the current laboratory capacity to screen for internal contamination is limited, rapid field screening methods can be useful in prioritising individuals. This study evaluated the suitability of a radiation portal monitor for such screening. A model of the portal monitor was created for use with models of six anthropomorphic phantoms in Monte Carlo N-Particle Transport Code Version 5 (MCNP) X-5 Monte Carlo Team (MCNP-A General Monte Carlo N-Particle Transport Code Version 5. LA-CP-03-0245. Vol. 2. Los Alamos National Laboratory, 2004.). The count rates of the portal monitor were simulated for inhalation and ingestion of likely radionuclides from an RDD for each of the phantoms. The time-dependant organ concentrations of the radionuclides were determined using Dose and Risk Calculation Software Eckerman, Leggett, Cristy, Nelson, Ryman, Sjoreen and Ward (Dose and Risk Calculation Software Ver. 8.4. ORNL/TM-2001/190. Oak Ridge National Laboratory, 2006.). Portal monitor count rates corresponding to a committed effective dose E(50) of 10 mSv are reported.

The roles of medical health physicists in a medical radiation emergency

Medical health physicists working in a clinical setting will have a number of key roles in the event of a nuclear or radiological emergency, such as a terrorist attack involving a radiological dispersal device or an improvised nuclear device. Their first responsibility, of course, is to assist hospital administrators and facility managers in developing radiological emergency response plans for their facilities and train staff prior to an emergency. During a hospital’s response to a nuclear or radiological emergency, medical health physicists may be asked to (1) evaluate the level of radiological contamination in or on incoming victims; (2) help the medical staff evaluate and understand the significance to patient and staff of the levels of radioactivity with which they are dealing; (3) orient responding medical staff with principles of dealing with radioactive contaminants; (4) provide guidance to staff on decontamination of patients, facilities, and the vehicles in which patients were transported; and (5) assist local public health authorities in monitoring people who are not injured but who have been or are concerned that they may have been exposed to radioactive materials or radiation as a result of the incident. Medical health physicists may also be called upon to communicate with staff, patients, and the media on radiological issues related to the event. Materials are available from a number of sources to assist in these efforts. The Centers for Disease Control and Prevention (CDC) is developing guidance in the areas of radiological population monitoring, handling contaminated fatalities, and using hospital equipment for emergency monitoring. CDC is also developing training and information materials that may be useful to medical health physicists who are called upon to assist in developing facility response plans or respond to a nuclear or radiological incident. Comments on these materials are encouraged.

Nuclear and radiological emergencies: Building capacity in medical physics to support response

Medical physicists represent a valuable asset at the disposal of a structured and planned response to nuclear or radiological emergencies (NREs), especially in the hospital environment. The recognition of this fact led the International Atomic Energy Agency (IAEA) and the International Organization for Medical Physics (IOMP) to start a fruitful collaboration aiming to improve education and training of medical physicists so that they may support response efforts in case of NREs. Existing shortcomings in specific technical areas were identified through international consultations supported by the IAEA and led to the development of a project aiming at preparing a specific and standardized training package for medical physicists in support to NREs. The Project was funded through extra-budgetary contribution from Japan within the IAEA Nuclear Safety Action Plan. This paper presents the work accomplished through that project and describes the current steps and future direction for enabling medical physicists to better support response to NREs.

Assessing internal contamination after the detonation of a radiological dispersion device using a 2×2-inch sodium iodide detector

The detonation of a radiological dispersion device may result in a situation where individuals inhale radioactive materials and require rapid assessment of internal contamination. The feasibility of using a 2×2-inch sodium-iodide detector to determine the committed effective dose to an individual following acute inhalation of gamma-emitting radionuclides was investigated. Experimental configurations of point sources with a polymethyl methacrylate slab phantom were used to validate Monte Carlo simulations. The validated detector model was used to simulate the responses for four detector positions on six different anthropomorphic phantoms. The nuclides examined included (241)Am, (60)Co, (137)Cs, (131)I and (192)Ir. Biokinetic modelling was employed to determine the distributed activity in the body as a function of post-inhalation time. The simulation and biokinetic data were used to determine time-dependent count-rate values at optimal detector locations on the body for each radionuclide corresponding to a target committed effective dose (E50) value of 250 mSv.

Use of epidemiological data and direct bioassay for prioritization of affected populations in a large-scale radiation emergency.

Following a radiation emergency, evacuated, sheltered or other members of the public would require monitoring for external and/or internal contamination and, if indicated, decontamination. In addition, the potentially-impacted population would be identified for biodosimetry/bioassay or needed medical treatment (chelation therapy, cytokine treatment, etc.) and prioritized for follow-up. Expeditious implementation of these activities presents many challenges, especially when a large population is affected. Furthermore, experience from previous radiation incidents has demonstrated that the number of people seeking monitoring for radioactive contamination (both external and internal) could be much higher than the actual number of contaminated individuals. In the United States, the Department of Health and Human Services is the lead agency to coordinate federal support for population monitoring activities. Population monitoring includes (1) monitoring people for external contamination; (2) monitoring people for internal contamination; (3) population decontamination; (4) collecting epidemiologic data regarding potentially exposed and/or contaminated individuals to prioritize the affected population for limited medical resources; (5) administering available pharmaceuticals for internal decontamination as deemed necessary by appropriate health officials; (6) performing dose reconstruction; and (7) establishing a registry to conduct long-term monitoring of this population for potential long-term health effects. This paper will focus on screening for internal contamination and will describe the use of early epidemiologic data as well as direct bioassay techniques to rapidly identify and prioritize the affected population for further analysis and medical attention.

Validation of Monte Carlo Simulation of a Thyroid Uptake System Using Various Sources and a Slab Phantom

Abstract In the event of a terrorist act involving a radiological agent, internal contamination due to inhalation is a potential health threat. When a large population is potentially impacted, there is need for methodology to serve as an initial screening or triage tool to rapidly identify individuals with significant amounts of internal contamination and to assist in prioritizing collection of large numbers of bioassay samples needed in such an incident. Common handheld radiation detectors and medical devices are tools that can effectively and rapidly screen a large number of people for internal contamination due to gamma-emitting isotopes. This work investigated the use of a common medical device, a thyroid uptake system or thyroid probe, in screening for internal contamination in individuals. The response of a thyroid uptake system in such a situation can be estimated by using a validated Monte Carlo model of the thyroid uptake system and various human phantoms. A computational model of the thyroid uptake system was built using the Los Alamos Particle Transport Code, MCNP Version 5. The validation of this computational model was demonstrated by comparisons to a series of benchmark measurements using the actual device and six isotopes with a range of gamma-ray emission energies.

Proposed “Exposure And Symptom Triage” (EAST) Tool to Assess Radiation Exposure After a Nuclear Detonation

ABSTRACTOne of the biggest medical challenges after the detonation of a nuclear device will be implementing a strategy to assess the severity of radiation exposure among survivors and to triage them appropriately. Those found to be at significant risk for radiation injury can be prioritized to receive potentially lifesaving myeloid cytokines and to be evacuated to other communities with intact health care infrastructure prior to the onset of severe complications of bone marrow suppression. Currently, the most efficient and accessible triage method is the use of sequential complete blood counts to assess lymphocyte depletion kinetics that correlate with estimated whole-body dose radiation exposure. However, even this simple test will likely not be available initially on the scale required to assess the at-risk population. Additional variables such as geographic location of exposure, sheltering, and signs and symptoms may be useful for initial sorting. An interdisciplinary working group composed of federal, state, and local public health experts proposes an Exposure And Symptom Triage (EAST) tool combining estimates of exposure from maps with clinical assessments and single lymphocyte counts if available. The proposed tool may help sort survivors efficiently at assembly centers near the damage and fallout zones and enable rapid prioritization for appropriate treatment and transport. (Disaster Med Public Health Preparedness. 2018; 12: 386-395).

GHSI emergency radionuclide bioassay laboratory network: Summary of a recent exercise

The Global Health Security Initiative (GHSI) established a laboratory network within the GHSI community to develop their collective surge capacity for radionuclide bioassay in response to a radiological or nuclear emergency. A recent exercise was conducted to test the participating laboratories for their capabilities in screening and in vitro assay of biological samples, performing internal dose assessment and providing advice on medical intervention, if necessary, using a urine sample spiked with a single radionuclide, 241Am. The laboratories were required to submit their reports according to the exercise schedule and using pre-formatted templates. Generally, the participating laboratories were found to be capable with respect to rapidly screening samples for radionuclide contamination, measuring the radionuclide in the samples, assessing the intake and radiation dose, and providing advice on medical intervention. However, gaps in bioassay measurement and dose assessment have been identified. The network may take steps to ensure that procedures and practices within this network be harmonised and a follow-up exercise be organised on a larger scale, with potential participation of laboratories from the networks coordinated by the International Atomic Energy Agency and the World Health Organization.