[en] Based on data from a national residential radon survey performed in 18 cities in Canada in the 1970's, an annual effective dose to the Canadian population due to indoor radon exposure was estimated at 0.71 mSv. An updated estimate of radon exposure in Canada has been made using additional indoor radon data from recent surveys in Ontario and Nova Scotia, and in 28 communities of British Columbia and 15 regions of Quebec. The associated annual effective dose to the Canadian population is now estimated to be 1.15 mSv. The percentage of homes in Canada with radon concentrations above the Canadian Radon Guideline of 200 Bq m^-3 is estimated to be about 3.3%. As might be expected, this number varies significantly (from a low of 1% of homes above the Guideline to a high of 19%) from region to region. Because more radon data are included in the current assessment, and the data set covers broader geographical areas, the current assessment better represents the radon exposure in Canada. (authors)

[en] The velvet cathode material of a 4-MeV, electron-beam injector was replaced with a metal cathode and driven by an ArF excimer laser. Time-resolved measurements of photo electron current and effective cathode temperature were made. A streak camera and B (magnetic field) probes were the primary diagnostics for the experiment. The streak camera determined effective cathode temperature in a single spatial dimension. Time-integrated photography was used to observe plasma formation in the cathode region. The results will be used to ascertain the feasibility of long-pulse (75 ns) beam generation for injection into a linear induction accelerator

[en] To be able to respond effectively to any radiological or nuclear emergency, a radiation accident registry is a valuable asset. This type of registry is able to assist responders in preparing for and managing situations during the event and in providing effective follow-up on the long-term health effects of persons exposed. It is especially important to register radiation-exposed people in vulnerable population groups, such as children and pregnant women, to ensure proper long-term health care and protection. As part of its national system of emergency preparedness for response to radiological or nuclear events (Canada) needs to develop a plan for a radiation accident registry. Apart from radiation dose information, this registry should also contain a sub-database of available medical facilities and necessary supplies as well as professionals specialising in radiation treatment and protection. Following the establishment of the registry, it should routinely be tested in training exercises to ensure its readiness for implementation whenever the need might arise. (authors)

[en] Exposure to indoor radon has been determined to be the second leading cause of lung cancer after tobacco smoking. Canadian population risk of radon induced lung cancer was assessed in 2005 with the radon distribution characteristics determined from a radon survey carried out in the late 1970's in 19 cities. In that survey, a grab sampling method was used to measure radon levels. The observed radon concentration in 14 000 Canadian homes surveyed followed a log-normal distribution with a geometric mean (GM) of 11.2 Bq m^-3 and a geometric standard deviation (GSD) of 3.9. Based on the information from that survey, it was estimated that ∼10 % of lung cancers in Canada resulted from indoor radon exposure. To gain a better understanding of radon concentrations in homes across the country, a national residential radon survey was launched in April 2009. In the recent survey, long-term (3 month or longer) indoor radon measurements were made in roughly 14 000 homes in 121 health regions across Canada. The observed radon concentrations follow, as expected, a log-normal distribution with a GM of 41.9 Bq m^-3 and a GSD of 2.8. Based on the more accurate radon distribution characteristics obtained from the recent cross-Canada radon survey, a re-assessment of Canadian population risk for radon induced lung cancer was undertaken. The theoretical estimates show that 16 % of lung cancer deaths among Canadians are attributable to indoor radon exposure. These results strongly suggest the ongoing need for the Canadian National Radon Program. In particular, there is a need for a focus on education and awareness by all levels of government, and in partnership with key stakeholders, to encourage Canadians to take action to reduce the risk from indoor radon exposure. (authors)

[en] To aid in protecting patients from unnecessary exposures and to reduce radiation burdens to the public, a system for tracking a patient's medical exposure history and related radiation doses would be a useful tool. A patient-centred exposure registry, the Patient Exposure Registry (PER), is a mechanism that provides this tracking. This article outlines the objectives of the proposed Canadian PER together with considerations and preliminary design of the registry. Implementation strategy is discussed. The strategy will allow many initiatives progressing in parallel such as backward data mining and forward development in order to make this important registry a reality in the near future. Published by Oxford Univ. Press on behalf of the Canadian Government 2010. (authors)

[en] In order to provide effective monitoring and follow-up on the health effects of individuals accidentally exposed to ionising radiation, a Radiation Accident Registry (RAR) has been designed and constructed as an extension to the existing National Dose Registry (NDR). The RAR has basic functions of recording, monitoring and reporting. This type of registry is able to assist responders in preparing for and managing situations during radiological events and in providing effective follow-up on the long-term health effects of persons exposed to ionising radiation. It is especially important to register radiation-exposed people in vulnerable population groups, such as children and pregnant women, to ensure proper long-term health care and protection. Even though radiation accidents are rare, a registry prepared for such accidents could involve a large population and, in some cases, require lifetime monitoring for individuals. One of the most challenging tasks associated with RAR is the assessment of radiation dose resulting from accidents. In some cases, the assessment of radiation doses to individuals could be a process requiring the involvement of various methods. The development of fast and accurate dose assessment tools will remain a long-term challenge associated with the RAR. To meet this challenge, further research activities in radiation dosimetry for individual monitoring are needed. (authors)

[en] After prolonged exposure to low temperatures (1 and 4 degrees C), human atrial trabeculae show poor recovery of contraction. At somewhat higher temperatures (12 and 20 degrees C), recovery is much better. Although better preservation of adenosine triphosphate and therefore improved contractile recovery might be expected after exposure to lower temperatures, it remained possible that, below a certain temperature, adenosine triphosphate-generating mechanisms could be slowed more than adenosine triphosphate utilization. To investigate this phenomenon further, we followed the time course of metabolic changes in human atrial appendages, harvested during cardiac bypass operations, at 1, 4, 12, and 20 degrees C using high-resolution 31P and 1H nuclear magnetic resonance spectroscopy. The results are quantitated by correlation with data obtained from biochemical assays on quick-frozen tissues. Initial adenosine triphosphate levels in myocytes of human atrial appendages are 3.3 to 4.3 mumol.gm-1 tissue wet weight. At 20 degrees C, adenosine triphosphate disappears after 6 hours; at 12 degrees C, about half the initial adenosine triphosphate is still observable at this time; at 4 degrees C or 1 degree C, the decline is still slower. Only a small contribution toward adenosine triphosphate maintenance comes from creatine phosphate, since creatine phosphate, inorganic phosphate, and total creatine levels in the appendage are low (less than 2 mumol.gm-1 tissue wet weight). Glycolysis is active at all temperatures; the rate of glycolysis correlates positively with increasing temperature. Adenosine triphosphate generated by glycolysis falls just short of demand at all temperatures, but the difference is small at 1 and 4 degrees C

[en] The Dual-Axis Radiographic Hydrodynamics Test (DARHT) facility will employ two 16-MeV, 3-kA Linear Induction Accelerators to produce intense, bremsstrahlung x-ray pulses for flash radiography. Technology demonstration of the key accelerator sub-systems is underway at the DARHT Integrated Test Stand (ITS), which will produce a 6-MeV, 3-kA, 60-ns flattop electron beam. The authors summarize measurements of ITS injector, pulsed-power, and accelerator cell performance. Time-resolved measurements of the electron beam parameters are also presented. These measurements indicate that the DARHT accelerator design is sufficiently advanced to provide the high quality electron beams required for radiography with sub-millimeter spatial resolution

[en] The Dual-Axis Radiographic Hydrodynamics Test (DARHT) facility will employ two 16-MeV, 3-kA Linear Induction Accelerators to produce intense, bremsstrahlung x-ray pulses for flash radiography. Technology demonstration of the key accelerator sub-systems is underway at the DARHT Integrated Test Stand (ITS), which will produce a 6-MeV, 3-kA, 60-ns flattop electron beam. We will summarized measurements of ITS injector, pulsed-power, and accelerator cell performance. Time-resolved measurements of the electron beam parameters will also be presented. These measurements indicate that the DARHT accelerator design is sufficiently advanced to provide the high quality electron beams required for radiography with sub-millimeter spatial resolution

[en] Surface flashover of a carbon fiber velvet cathode generates a discharge from which electrons are relativistically accelerated to γ ranging from 4.9 to 8.8 through a 17.8 cm diode. This discharge is assumed to be a hydrocarbon mixture. The principal objective of these experiments is to quantify the dynamics over the ∼100 ns pulse of the plasma discharge generated on the surface of the velvet cathode and across the anode-cathode (A-K) gap. A qualitative comparison of calculated and measured results is presented, which includes time resolved measurements with a photomultiplier tube and charge-coupled device images. In addition, initial visible spectroscopy measurements will also be presented confirming the ion species are dominated by hydrogen