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PubMed1984

Shielding hospital rooms for brachytherapy patients: design, regulatory and cost/benefit factors.

The current regulations of the U.S. Nuclear Regulatory Commission (NRC) normally require limitation of radiation exposure in any part of unrestricted occupied areas to 2 mrem in any one hour and to 100 mrem in 7 days. To meet these limits when patients are treated therapeutically with radioactive materials, it is advisable to designate specific rooms in a hospital and often necessary to incorporate substantial costly shielding into one or more walls and the room door. Plans have been formulated for shielding existing hospital rooms housing brachytherapy patients receiving 192Ir and 137Cs therapy in order to meet the above NRC requirements for adjacent corridors and rooms. Typical shielding thicknesses required are 4-6 in. of concrete for certain walls and 1/4 in. of lead in the doors. Shielding costs are approx. $6000 per room for one shielded wall and a shielded door. Applying recent estimates of the cancer risk from low-level gamma radiation, the cost of shielding per cancer fatality averted has been estimated to range from $1.8 million to $10.9 million. Cost/benefit comparisons with many other life-saving activities suggest that these costs and the application of the 2 mrem/hr limit which necessitated them are not justified.

Brachytherapy↗
PubMed1986

Effect of partition walls and neighboring buildings on the indoor exposure rate due to cosmic-ray muons.

Numerical calculations were done of the indoor exposure rate due to the cosmic rays. Only muons were considered, and the calculations were done within a two-dimensional framework under the non-scattering approximation. The effects of various structural parameters on the level and the distribution of the exposure rate were studied by a case control method. It was shown that a building's dimensions and the floor thickness were important in all cases. However, the effect of partition walls would become significant only when the partition number is large. The effect of neighboring buildings would be especially important in the lower floors of tall buildings. In such a case, attention is necessary not only to the buildings' internal structures but also to the relationship between that particular building and its neighborhood. The maximum amplitude of the possible variation of the exposure rate due to the change of any single structural parameter would be 30% in ordinary Japanese housing conditions.

Building Codes↗
PubMed1998

Primary shielding barriers for diagnostic x-ray facilities: a new model.

Traditional methods of diagnostic x-ray shielding design assume that the raw primary beam impinges directly on the structural barrier with attenuation by the patient and by the hardware in the x-ray beam (cassette, cassette holder, x-ray table) being ignored. Moreover, primary barrier calculations are done assuming a single, conservatively high value of the operating potential, rather than the lower kVp values more representative of clinical usage. This results in extreme conservatism, which is no longer defensible in light of the lowered dose limit to a member of the general public of 1 mSv y-1, which is equal in magnitude to natural background radiation (excluding radon). A shielding model is developed that accounts for attenuation of the primary beam prior to impinging on the structural barrier and which uses a workload which is distributed over a range of clinically realistic operating potentials. The resulting model is as simple to use as that, assuming a single value of the kVp. Sample calculations are performed and the results compared to those from more traditional shielding calculation methods.

Building Codes↗
PubMed1998

Radon reduction systems in the construction of new houses in Gainesville, Florida.

High radon level exposures increase human risk of lung cancer. The objective of this paper is to present the results of the effectiveness of applying the Enkavent mat method and the suction pit method; as tested by a University of Florida research team; to reduce radon entry in new houses built in the city of Gainesville and the surrounding Alachua County area in Florida. Both of these passive techniques include placement of a barrier under the concrete floor slab right on top of the soil at the new building sites. Passive and active techniques applied in the construction of new houses reduced radon levels to below the minimum requirements of 148 Bq m(-3) (4 pCi L(-1)). The mitigation systems investigated in this research were adopted by the Florida Legislature to become part of the new building construction code in Florida.

Air Pollutants, Radioactive↗
PubMed1999

Radon action level for high-rise buildings.

Radon and its progeny are the major contributors to the natural radiation dose received by human beings. Many countries and radiological authorities have recommended radon action levels to limit the indoor radon concentrations and, hence, the annual doses to the general public. Since the sources of indoor radon and the methods for reducing its concentration are different for different types of buildings, social and economic factors have to be considered when setting the action level. But so far no action levels are specifically recommended for cities that have dwellings and offices all housed in high-rise buildings. In this study, an optimization approach was used to determine an action level for high-rise buildings based on data obtained through previous territory-wide radon surveys. A protection cost of HK$0.044 per unit fresh air change rate per unit volume and a detriment cost of HK$120,000 per person-Sv were used, which gave a minimum total cost at an action level of 200 Bq m(-3). The optimization analyses were repeated for different simulated radon distributions and living environment, which resulted in quite significantly different action levels. Finally, an action level of 200 Bq m(-3) was recommended for existing buildings and 150 Bq m(-3) for newly built buildings.

Building Codes↗
PubMedDate not supplied

Protecting infants in healthcare facilities from abduction: a facility's search for a sound infant security system.

Metropolitan Methodist Hospital, a 279-bed facility, had an electronic infant security system frequently in need of repairs. The vendor became increasingly difficult to locate, and so the decision was made to replace the system. A literature search of vendors and agencies supporting hospitals in the prevention of infant abductions; solicitation of information from facilities experiencing abductions; and onsite tours of facilities were most beneficial in determining a new system. As a result, the facility purchased a state-of-the-art infant security system and agreed to participate as a beta site for mother-baby recognition identification bands, an added security feature not yet on the market. This article describes the process of evaluating and selecting an infant security system in order to reduce the risk of infant abduction.

Building Codes↗
PubMed1996

War zone paediatrics in Rwanda.

Children are particularly vulnerable to injury and death in two types of 20th century conflicts; terrorist attack and civil war. This account describes some first-hand experiences of the aftermath of the Rwandan Civil War of 1994. Events leading to the conflict are described, eye witness accounts of child trauma during the war are recorded and the medical problems (currently ongoing) affecting children are described. Over a period of 3 months from April to June 1994, between half and one million Rwandese, a significant proportion of them women and children, were murdered in brutal hand-to-hand killing, dying from close-quarter gunshot and machete slaughter. Nearly half of the population became refugees in neighbouring countries or displaced persons in their own land. UNAMIR II, the United Nations Emergency Humanitarian Response, grew to some 7000 persons by May 1995. Medical aid was provided by emergency medical contingents from the United Kingdom, Canada and Australia, the latter through its Australian Medical Support Force, providing the definitive emergency medical infrastructure from August 1994. In the consequent post-war civil and social disruption, children suffered from burns, cholera and from motor vehicle trauma. Ongoing landmine blasts continue to affect children and adolescents especially. A new International humanitarian code to build a time-expiry device into landmines and other similar ordinance is urgently required as the post-conflict ongoing disasters in Rwanda, Afghanistan and Cambodia illustrate. Current problems affecting children include an increasing risk of HIV infection, trauma and the special humanitarian needs of thousands of orphans.

Child↗
PubMed1996

The World Trade Center bombing: injury prevention strategies for high-rise building fires.

The WTC disaster provided an opportunity to look for ways to prevent morbidity among occupants of high-rise buildings during fires. This paper first describes the overall morbidity resulting from the explosion and fire, and second, presents the results of a case-control study carried out to identify risk factors for smoke-related morbidity. The main ones include: increased age, presence of a pre-existing cardio-pulmonary condition, entrapment in a lift and prolonged evacuation time. Study results point to the importance of the following safety systems during high-rise building fires: smoke-control systems with separate emergency power sources; lift-cars, lift-car position-monitoring systems, and lift-car communication systems with separate emergency power sources; two-way emergency communication systems on all floors and in stairwells; stairwells with emergency lighting and designed for the rapid egress of crowds; evacuation systems/equipment to assist in the evacuation of vulnerable people (elderly, infirm). Also important are evacuation plans that include regularly scheduled safety training and evacuation drills.

Adolescent↗
PubMed1996

The health effects of earthquakes in the mid-1990s.

This paper gives an overview of the global pattern of casualties in earthquakes which occurred during the 30-month period from 1 September 1993 to 29 February 1996. It also describes some of the behavioural and logistical regularities associated with mortality and morbidity in these events. Of 83 earthquakes studied, there were casualties in 49. Lethal earthquakes occurred in rapid succession in Indonesia, China, Colombia and Iran. In the events studied, a disproportionate number of deaths and injuries occurred during the first six hours of the day and in earthquakes with magnitudes between 6.5 and 7.4. Ratios of death to injury varied markedly (though with some averages close to 1:3), as did the nature and causes of mortality and morbidity and the proportion of serious to slight injuries. As expected on the basis of previous knowledge, few problems were caused by post-earthquake illness and disease. Also, as expected, building collapse was the principal source of casualties: tsunamis, landslides, debris flows and bridge collapses were the main secondary causes. In addition, new findings are presented on the temporal sequence of casualty estimates after seismic disaster. In synthesis, though mortality in earthquakes may have been low in relation to long-term averages, the interval of time studied was probably typical of other periods in which seismic catastrophes were relatively limited in scope.

Building Codes↗
PubMed1987

Use of risk assessment methods in the certification of decontaminated buildings.

Accidental events such as fires, explosions, and leaks often result in large-scale contaminations of buildings with toxic chemicals. After decontamination, the certification for original use requires testing for residual contamination. The two basic kinds of sampling plans in use up to recently both fall short of the required performance. Their deficiencies are analyzed in terms of the scientific questions implicit in both the sampling plan and the subsequent statistical evaluation. A sampling strategy of a new kind is proposed and discussed in the same context. It is motivated by concern for the long-term safety of the building's occupants and is, therefore, based on factors important in risk assessment. Three different sampling plans are derived in the framework of this methodology, two of which have already been used in actual certification proceedings.

Algorithms↗
PubMed2001

Enhancing maximum measurable sound reduction index using sound intensity method and strong receiving room absorption.

The sound intensity method is usually recommended instead of the pressure method in the presence of strong flanking transmission. Especially when small and/or heavy specimens are tested, the flanking often causes problems in laboratories practicing only the pressure method. The purpose of this study was to determine experimentally the difference between the maximum sound reduction indices obtained by the intensity method, RI,max, and by the pressure method, Rmax. In addition, the influence of adding room absorption to the receiving room was studied. The experiments were carried out in an ordinary two-room test laboratory. The exact value of RI,max was estimated by applying a fitting equation to the measured data points. The fitting equation involved the dependence of the pressure-intensity indicator on measured acoustical parameters. In an empty receiving room, the difference between RI,max and Rmax was 4-15 dB, depending on frequency. When the average reverberation time was reduced from 3.5 to 0.6 s, the values of RI,max increased by 2-10 dB compared to the results in the empty room. Thus, it is possible to measure wall structures having 9-22 dB better sound reduction index using the intensity method than with the pressure method. This facilitates the measurements of small and/or heavy specimens in the presence of flanking. Moreover, when new laboratories are designed, the intensity method is an alternative to the pressure method which presupposes expensive isolation structures between the rooms.

Building Codes↗
PubMed1989

Indoor human response to blast sounds that generate rattles.

The two major noise sources that cause environmental problems for the U. S. Army are helicopters and large weapons such as artillery, tanks, and demolition. These large weapons produce blast sounds that contain little energy above 200 Hz and that are particularly troublesome to deal with because they excite rattles in structures. The purpose of this study was to systematically test subjective response to the presence or absence of rattles in otherwise similar blast sound environments. A second purpose of the study was to test if there were structural changes that could reduce annoyance within the indoor blast sound environment. This study was done using a specially constructed test house and highly repeatable shake table to generate the blast sounds. The data clearly show that no commonly used environmental noise measure adequately describes the indoor environment when the blast excites rattles. Although the indoor blast ASEL changes by only about a decibel or so (and the indoor blast CSEL changes by even less), the subjective response changes by up to 13 dB. At low blast levels, the increase in human annoyance response is largest, and this annoyance response offset decreases to about 6 dB when the outside, flat-weighted peak sound-pressure level of the blast increases from 112 to 122 dB.

Acoustics↗