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Nuclear security and radiological preparedness for the olympic games, athens 2004: lessons learned for organizing major public events.

In light of the exceptional circumstances that arose from hosting the Olympic Games in Athens in 2004 and from recent terrorist events internationally, Greece attributes the highest priority to security issues. According to its statutory role, the Greek Atomic Energy Commission is responsible for emergency preparedness and response in case of nuclear and radiological events, and advises the Government on the measures and interventions necessary to protect the public. In this context, the Commission participated in the Nuclear, Radiological, Biological, and Chemical Threat National Emergency Plan, specially developed for the Olympic Games, and coordinated by the Olympic Games Security Division. The objective of this paper is to share the experience gained during the organization of the Olympic Games and to present the nuclear security program implemented prior to, during, and beyond the Games, in order to prevent, detect, assess, and respond to the threat of nuclear terrorism. This program adopted a multi-area coverage of nuclear security, including physical protection of nuclear and radiological facilities, prevention of smuggling of radioactive materials through borders, prevention of dispersion of these materials into the Olympic venues, enhancement of emergency preparedness and response to radiological events, upgrading of the technical infrastructure, establishment of new procedures for assessing the threat and responding to radiological incidents, and training personnel belonging to several organizations involved in the National Emergency Response Plan. Finally, the close cooperation of Greek Authorities with the International Atomic Energy Agency and the U.S. Department of Energy, under the coordination of the Greek Atomic Energy Commission, is also discussed.

Civil Defense↗

The Spanish Protocol for radiological surveillance of metal recycling: a collaboration of government and industry.

The presence of radioactive materials in scrap metal has been detected relatively often in recent years. As a result of an accidental melting of a 137Cs source in a Spanish steel mill (Acerinox) in 1998, the national authorities, the involved private companies, and the main trade unions drafted a protocol for prevention of and responding to such events ("Spanish Protocol"). The Protocol was signed in 1999. The number of subscribing companies is 90. The Protocol is a voluntary agreement defining the radiological surveillance of scrap metal and its products and the duties and rights of the signatories. From the effective date of the Protocol to December 2004, 461 pieces of ferric scrap were detected including sources of radiation and contaminated metal. Four melting incidents have happened in different companies.

Cooperative Behavior↗

The effectiveness of radon remediation in Irish schools.

An advisory reference level of 200 Bq m(-3) and a statutory reference level of 400 Bq m(-3) apply to radon exposure in Irish schools. Following the results of a national survey of radon in Irish schools, several hundred classrooms were identified in which the reference levels were exceeded and a remediation program was put in place. This paper provides an initial analysis of the effectiveness of that remediation program. All remediation techniques proved successful in reducing radon concentrations. Active systems such as radon sumps and fan assisted under-floor ventilation were generally applied in rooms with radon concentrations above 400 Bq m(-3). These proved most effective with average radon reduction factors of 9 to 34 being achieved for radon sumps and 13 to 57 for fan assisted under-floor ventilation. Both of these techniques achieved maximum radon reduction factors in excess of 100. The highest average reduction factors were associated with the highest initial radon concentrations. Passive remediation systems such as wall and window vents were used to increase background ventilation in rooms with radon concentrations below 400 Bq m(-3) and achieved average radon reductions of approximately 55%. Following the installation of active remediation systems, the radon concentration in adjacent rooms, i.e., rooms in which the radon concentration was already below 200 Bq m(-3) and therefore did not require remediation, was further reduced by an average of 25%. The long-term effectiveness of a number of radon sump systems with at least three years operation showed no evidence of fan failures. This study showed an apparent increase in sump effectiveness with time as indicated by an increase in radon reduction factors during this period.

Air Pollutants, Radioactive↗

Radiation protection at an aviation museum.

The U.S. Nuclear Regulatory Commission (U.S. NRC) will soon publish a proposed amendment to its rules that will classify the naturally occurring isotope Ra as "byproduct material" subject to its regulatory control. One of the uses of radium in the first half of the twentieth century was as a source of energy that would make certain consumer products "glow in the dark." In addition to wristwatches and other timepieces, this form of self-luminescence was widely used on aircraft instruments. There have been a number of facilities where large numbers of such instruments were stored and leakage of this isotope occurred. Subsequent decontamination of these areas, including expensive disposal of the radioactive waste, was required. We were asked to evaluate the potential hazards of aircraft and aircraft instruments at a museum in New York City, specifically the decommissioned aircraft carrier USS Intrepid. We present the results of our investigation and discuss the implications as they relate to the proposed new U.S. NRC regulations and compatibility issues with State regulations.

Aviation↗

A generic-tee-plenum mixing system for application to single point aerosol sampling in stacks and ducts.

The ANSI/HPS-N13.1-1999 standard is based on the concept of obtaining a single point representative sample from a location where the velocity and contaminant profiles are relatively uniform. It is difficult to predict the level of mixing in an arbitrary stack or duct without experimental data to meet the ANSI/HPS N13.1-1999 requirements. The goal of this study was to develop experimental data for a range of conditions in "S" (S-shaped configuration) duct systems with different mixing elements and "S" systems having one or two mixing elements. Results were presented in terms of the coefficients of variation (COVs) for velocity, tracer gas, and 10-mum aerodynamic diameter (AD) aerosol particle profiles at different downstream locations for each mixing element. Five mixing elements were tested, including a 90 degrees elbow, a commercial static mixer, a Small-Horizontal Generic-Tee-Plenum (SH-GTP), a Small-Vertical Generic-Tee-Plenum (SV-GTP), and a Large-Horizontal Generic-Tee-Plenum (LH-GTP) system. The COVs for velocity, gas concentration, and aerosol particles for the three GTP systems were all determined to be less than 8%. Tests with two different sizes of GTPs were conducted, and the results showed the performance of the GTPs was relatively unaffected by either size or velocity as reflected by the Reynolds number. The pressure coefficients were 0.59, 0.57, and 0.65, respectively, for the SH-GTP, SV-GTP, and LH-GTP. The pressure drop for the GTPs was approximately twice that of the round elbow, but a factor of 5 less than a Type IV Air Blender. The GTP was developed to provide a sampling location less than 4-duct diameters downstream of a mixing element with low pressure drop condition. The object of the developmental effort was to provide a system that could be employed in new stack; however, the concept of GTPs could also be retrofitted onto existing system applications as well. Results from these tests show that the system performance is well within the ANSI/HPS N13.1-1999 mixing criteria--the COVs for velocity, tracer gas, and 10-microm AD aerosol particles are less than the 20% criteria levels.

Aerosols↗

Radiation exposure in trauma patients.

BACKGROUND: Trauma patients are exposed to a large amount of ionizing radiation. Radiologic examinations may include a multitude of plain films, computed tomography scans, and/or fluoroscopic examination. Previous studies have assessed radiation exposure to staff members at trauma centers, and in pregnant trauma patients. The purpose of the current study is to evaluate the amount of radiation to which trauma patients are exposed in a Level I trauma center. METHODS: The study used a prospective cohort design. All patients for whom a trauma code was activated between the months of September 2004 and July of 2005 were eligible to be enrolled in the study. Upon arrival to the trauma bay, a dosimeter badge, that measures ionizing radiation, was attached to a Velcro bracelet on the wrist of the patient. The badges were removed at the time of discharge from the hospital and analyzed. RESULTS: Data were collected on 224 patients (167 adults, 57 pediatric). The median amount of radiation exposure to all patients equaled 68 MREM (Interquartile range 31-181). A significant increase in the median amount of radiation exposure was found in patients with orthopedic injuries (107 MREM vs. 45 MREM), an Injury Severity Score (ISS) >15 (107 MREM vs. 46 MREM), a length of stay >than 1 week (105 MREM vs. 65 MREM), age >18 (82 MREM vs. 44 MREM), and when >11 radiologic procedures were performed (127 MREM vs. 46 MREM). CONCLUSION: Trauma patients are being exposed to high amounts of radiation. Patients with orthopedic injuries, and those more severely injured, are at an increased risk. Further precautions to limit radiation exposure in this population are needed.

Adult↗

Intracranial interstitial radiation.

Primary malignant brain tumors are fatal, with 90% of patients having these tumors dying within two years following diagnosis. Cranial interstitial radiation therapy, a technique under investigation to control these tumors, involves implantation of radioactive iodine 125 seeds into the tumor bed by stereotaxic technique. The interstitial radiation technique, monitoring of radiation, and nursing care of patients are discussed. Case histories are presented, along with discussion of results attained using this therapy, and its future.

Adult↗

Effects of target fragmentation on evaluation of LET spectra from space radiation in low-earth orbit (LEO) environment: impact on SEU predictions.

Recent improvements in the radiation transport code HZETRN/BRYNTRN and galactic cosmic ray environmental model have provided an opportunity to investigate the effects of target fragmentation on estimates of single event upset (SEU) rates for spacecraft memory devices. Since target fragments are mostly of very low energy, an SEU prediction model has been derived in terms of particle energy rather than linear energy transfer (LET) to account for nonlinear relationship between range and energy. Predictions are made for SEU rates observed on two Shuttle flights, each at low and high inclination orbit. Corrections due to track structure effects are made for both high energy ions with track structure larger than device sensitive volume and for low energy ions with dense track where charge recombination is important. Results indicate contributions from target fragments are relatively important at large shield depths (or any thick structure material) and at low inclination orbit. Consequently, a more consistent set of predictions for upset rates observed in these two flights is reached when compared to an earlier analysis with CREME model. It is also observed that the errors produced by assuming linear relationship in range and energy in the earlier analysis have fortuitously canceled out the errors for not considering target fragmentation and track structure effects.

Aluminum↗

Radiation doses to staff involved in sentinel node operations for breast cancer.

BACKGROUND: The use of radioactive compounds for sentinel node biopsy is now a generally accepted part of the surgical treatment of breast cancer and melanoma, with the risk of radiation exposure to the operating team. The aim of this investigation was to study the levels of this exposure in relation to the permissible radiation dose limits. METHODS: The radiation exposure to the hands and bodies of the operating surgeons (the 'risk persons') was measured by thermoluminescent dosimeters in 79 operations and to the pathologists handling the specimens in 17 cases. Radioactivity and dose rate measurement from tumours and breast specimens were also performed. RESULTS: During an operation the mean skin dose (+/-SD) to the thermoluminescent dosimeters placed at the hand and the abdominal wall were 0.04 +/- 0.04 mSv (79 operations) and 0.01 +/- 0.02 mSv (67 operations) respectively. For the pathologist, the mean hand dose per operation was below the detection limit (17 operations). Correlation between the measured dose rate and the radioactive content of the tumours was 0.998. CONCLUSIONS: The radiation exposure to the staff involved in sentinel node (SN) biopsy for breast cancer using radioactive labelled tracers will be considerably below the permissible limits, even with high numbers of SN biopsy procedures. Pregnant staff members should participate in <100 SN operations.

Body Burden↗

Assessing dental practice quality by evaluating radiology items.

The DEMCAD dental office assessment instrument was developed to evaluate practice quality using Donebedian's quality assessment model of structure, process, and outcome. This previously validated instrument takes about six hours to complete. Subsequent analysis was undertaken to determine whether an abbreviated office assessment based on the evaluation of radiology items was sufficiently sensitive, specific, and practical to be used as a screening instrument for identifying dental offices with very low evaluation scores. Data for this analysis were obtained from 300 volunteer general dental practices evaluated in the field testing of the DEMCAD instrument. The nine radiology structure items predicted very poorly the overall structure scores. However, 13 radiology process items predicted overall process scores quite accurately. Four of the 13 radiology process items (periodontal diagnoses recorded, interdental bone shown on x-rays, caries diagnoses recorded, and current x-rays mounted) produced a combined R2 of .58. These four radiology variables predicted the 10 percent of the dental practices with the lowest overall process score with 87 percent sensitivity and 93 percent specificity. This analysis showed that an abbreviated dental practice process quality assessment using oral radiology items in an audit of patients' records may be feasible as a screening test for dental office assessment.

Alveolar Process↗

Reduction of exposure of newborns and caregivers to very high electromagnetic fields produced by incubators.

The aims of this paper is to measure whether ferromagnetic panels sufficiently reduce the high electromagnetic fields (EMF) to which newborns are exposed in incubators and to which caregivers are exposed when working near the incubators. We measured EMF at mattress level in three neonatal incubators with and without ferromagnetic panels between the electric motor and the mattress. We then measured the EMF at the level of the maximum emission point for caregivers, i.e., near the display panel. The ferromagnetic panels were (a) 5 mm thick iron, (b), (c), (d) respectively, one, two, and three sheets of 0.3 mm thick mu-metal. The weight of iron sheet was 4 g/cm2, and mu-metal 0.2 g/cm2. The use of the ferromagnetic panels significantly reduced the EMF. No significant difference in attenuation was recorded using one, two, or, three sheets of mu-metal, or a single sheet of iron. One, two, and three sheets of mu-metal reduced EMFs by 77%, 82%, and 84.3%, respectively; the reduction with iron was 80%. EMF values measured in incubators were higher than those to which the general population is exposed. The use of ferromagnetic panels significantly reduces the level of EMFs to which neonates and caregivers are exposed.

Caregivers↗

Helical tomotherapy radiation leakage and shielding considerations.

Leakage radiation and room shielding considerations increase significantly for intensity-modulated radiation therapy (IMRT) treatments due to the increased beam-on time to deliver modulated fields. Tomotherapy, with its slice by slice approach to IMRT, further exacerbates this increase. Accordingly, additional shielding is used in tomotherapy machines to reduce unwanted radiation. The competing effects of the high modulation and the enhanced shielding were studied. The overall room leakage radiation levels are presented for the continuous gantry rotations, which are always used during treatments. The measured leakage at 4 m from the isocenter is less than 3 x 10(-4) relative to calibration output. Primary radiation exposure levels were investigated as well. The effect of forward-directed leakage through the beam-collimation system was studied, as this is the leakage dose the patient would receive in the course of a treatment. A 12-min treatment was calculated to produce only 1% patient leakage dose to the periphery region. Longer treatment times might yield less patient dose if the field width selected is correspondingly narrower. A method for estimating the worst-case leakage dose a patient would receive is presented.

Body Burden↗

Patient self-attenuation and technologist dose in positron emission tomography.

Positron emission tomography (PET), with 511-keV radiation and long patient-uptake times, presents unique radiation safety concerns. This two-part study considers aspects of PET radiation safety as they relate to PET suite design, dose to the public, and technologist occupational dose. In the first part of the study, the self-attenuation of radiation by patients' bodies was quantified. The radiation exposure was measured at three positions from 64 patients injected with fluorine-18 fluorodeoxyglucose (FDG) during the uptake period. Compared with an in vitro control used as a point source, a significant decrease in exposure (>40% at 1 m) was observed due to nonuniform distribution of FDG and attenuation within the patients. The attenuation data are consistent with results from simulations [M. E. Phelps, "Comments and Perspectives," J. Nucl. Med. 45, 1601 (2004)] that treat the body as a uniform, water-filled cylinder. As distance is often the principal source of protection for 511-keV radiation, the considerable self-attenuation may allow for more compact PET suites. However, despite high patient self-attenuation, shielding, and standard precautionary measures, PET technologist occupational doses can remain quite high (approximately 12 mSv/year). The second part of this study tracked the daily dose received by PET technologists. Close technologist-patient interaction both during and following FDG administration, as much as 20 min/study, contribute to the high doses and point to the need for a more innovative approach to radiation protection for PET technologists.

Allied Health Personnel↗