A U.S. Multicenter Study of Recorded Occupational Radiation Badge Doses in Nuclear Medicine.

Purpose To summarize occupational badge doses recorded for a sample of U.S. nuclear medicine technologists. Materials and Methods Nine large U.S. medical institutions identified 208 former and current nuclear medicine technologists certified after 1979 and linked these individuals to historic badge dose records maintained by a commercial dosimetry company (Landauer), yielding a total of 2618 annual dose records. The distributions of annual and cumulative occupational doses were described by using summary statistics. Results Between 1992 and 2015, the median annual personal dose equivalent per nuclear medicine technologist was 2.18 mSv (interquartile range [IQR], 1.25-3.47 mSv; mean, 2.69 mSv). Median annual personal dose equivalents remained relatively constant over this period (range, 1.40-3.30 mSv), while maximum values generally increased over time (from 8.00 mSv in 1992 to 13.9 mSv in 2015). The median cumulative personal dose equivalent was 32.9 mSv (IQR, 18.1-65.5 mSv; mean, 51.4 mSv) for 45 technologists who had complete information and remained employed through 2015. Conclusion Occupational radiation doses were well below the established occupational limits and were consistent with those observed for nuclear medicine technologists worldwide and were greater than those observed for nuclear and general medical workers in the United States These results should be informative for radiation monitoring and safety efforts in nuclear medicine departments. © RSNA, 2018 Online supplemental material is available for this article.

Photon energy readings in OSL dosimeter filters: an application to retrospective dose estimation for nuclear medicine workers.

This work investigates the applicability of using data from personal monitoring dosimeters to assess photon energies to which medical workers were exposed. Such determinations would be important for retrospective assessments of organ doses to be used in occupational radiation epidemiology studies, particularly in the absence of work history or other information regarding the energy of the radiation source. Monthly personal dose equivalents and filter ratios under two different metallic filters contained in the Luxel+® dosimeter were collected from Landauer, Inc. from 19 nuclear medicine (NM) technologists employed by three medical institutions, the institution A only performing traditional NM imaging (primarily using 99m Tc) and institutions B and C also performing positron emission tomography (PET, using 18F). Calibration data of the Luxel+® dosimeter for various xray spectra were used to establish ranges of filter ratios from 1.1 to 1.6 for 99m Tc and below 1.1 for 18F. Median filter ratios were 1.33 (Interquartile range (IQR), 0.15) for institution A, 1.08 (IQR, 0.16) for institution B, and 1.08 (IQR, 0.14) for institution C. The distributions of these filter ratios were statistically-significantly different between the institution A only performing traditional NM imaging and institutions B and C also performing PET imaging. In this proof-of-concept study, filter ratios from personal monitoring dosimeters were used to assess differences in photon energies to which NM technologists were exposed. Dosimeters from technologists only performing traditional NM procedures mostly showed Al/Cu filter ratios above 1.2, those likely performing only PET in a particular month had filter ratios below 1.1, and those which showed filter ratios between 1.1 and 1.2 likely came from technologists rotating between traditional NM and PET imaging in the same month. These results suggest that it is possible to distinguish technologists who only worked with higher-energy procedures versus those who only worked with other types of NM procedures.

A qualitative investigation of patients' understanding of carbohydrate in the clinical management of type 2 diabetes.

BACKGROUND: A healthy diet is the cornerstone of type 2 diabetes (T2DM) self-management. Carbohydrate is of particular interest as the nutrient with the greatest direct effect on blood glucose (BG) levels. The present study aimed to explore T2DM patients' understanding of carbohydrate and beliefs around the role of carbohydrate in T2DM management. METHODS: Fifteen semi-structured interviews were conducted with T2DM patients. Interviews were audio-recorded and transcribed, and a deductive thematic approach to analysis was employed using the Framework method. RESULTS: Four significant themes emerged: (i) a naïve conceptual understanding of carbohydrate and sugar-centric specificity to dietary behaviours; (ii) a narrow focus on BG management to the neglect of overall dietary balance; (iii) positive reception of moderate dietary advice focused on portion control from healthcare professionals (HCPs); and (iv) the impact of external moderators of dietary choices, including the influence of significant others, emotional and opportunistic eating and budgetary constraints. CONCLUSIONS: Participants' beliefs and understanding of carbohydrate led to an overemphasis on sugar restriction for blood glucose control to the neglect of their overall dietary balance. Diabetes educators need to place greater emphasis on the role of various types of carbohydrate foods for glycaemic control, as well as on concepts of wider metabolic health, during T2DM dietary education. Participants placed a high level of trust and value on practical, moderate portion control advice from HCPs regarding carbohydrate foods. However, HCPs need to be cognisant of external moderators of behaviour, such as the influence of family and friends, budgetary constraints and environmental eating triggers.

Mortality among medical radiation workers in the United States, 1965-2016.

BACKGROUND: Estimates of radiation risks following prolonged exposures at low doses and low-dose rates are uncertain. Medical radiation workers are a major component of the Million Person Study (MPS) of low-dose health effects. Annual personal dose equivalents, HP(10), for individual workers are available to facilitate dose-response analyses for lung cancer, leukemia, ischemic heart disease (IHD) and other causes of death. MATERIALS AND METHODS: The Landauer, Inc. dosimetry database identified 109,019 medical and associated radiation workers first monitored 1965-1994. Vital status and cause of death were determined through 2016. Mean absorbed doses to red bone marrow (RBM), lung, heart, and other organs were estimated by adjusting the recorded HP(10) for each worker by scaling factors, accounting for exposure geometry, the energy of the incident photon radiation, sex of the worker and whether an apron was worn. There were 4 exposure scenarios: general radiology characterized by low-energy x-ray exposure with no lead apron use, interventional radiologists/cardiologists who wore aprons, nuclear medicine personnel and radiation oncologists exposed to high-energy photon radiation, and other workers. Standardized mortality ratio (SMR) analyses were performed. Cox proportional hazards models were used to estimate organ-specific radiation risks. RESULTS: Overall, 11,433 deaths occurred (SMR 0.60; 95%CI 0.59,0.61), 126 from leukemia other than chronic lymphocytic leukemia (CLL), 850 from lung cancer, and 1654 from IHD. The mean duration of monitoring was 23.7 y. The excess relative rate (ERR) per 100 mGy was estimated as 0.10 (95% CI -0.34, 0.54) for leukemia other than CLL, 0.15 (0.02, 0.27) for lung cancer, and -0.10 (-0.27, 0.06) for IHD. The ERR for lung cancer was 0.16 (0.01, 0.32) among the 55,218 male workers and 0.09 (-0.19, 0.36) among the 53,801 female workers; a difference that was not statistically significant (p-value = 0.23). CONCLUSIONS: Medical radiation workers were at increased risk for lung cancer that was higher among men than women, although this difference was not statistically significant. In contrast, the study of Japanese atomic bomb survivors exposed briefly to radiation in 1945 found females to be nearly 3 times the radiation risk of lung cancer compared with males on a relative scale. For medical workers, there were no statistically significant radiation associations with leukemia excluding CLL, IHD or other specific causes of death. Combining these data with other cohorts within the MPS, such as nuclear power plant workers and nuclear submariners, will enable more precise estimates of radiation risks at relatively low cumulative doses.

Calcaneus Fracture and Posterior Arthroscopic Primary Subtalar Arthrodesis (C-PASTA).

Complex intra-articular calcaneal fractures often resulted in secondary pain and deformity, requiring subsequent subtalar arthrodesis1-3. The literature suggests that primary subtalar arthrodesis in the acute period has good functional results2,3. The literature also demonstrates that posterior arthroscopic subtalar arthrodesis for chronic arthritis has favorable results5. Thus, we propose an approach to treating these difficult intra-articular calcaneal fractures that utilizes a posterior arthroscopic primary subtalar arthrodesis technique-aptly named Calcaneus Fracture and Posterior Arthroscopic Primary Subtalar Arthrodesis (C-PASTA). Description: The procedure begins with the patient in the prone position. The subtalar joint is visualized with a 1.9-mm flexible camera through a standard posterior arthroscopic approach. With the help of the C-arm, position in the subtalar joint space is confirmed. The joint space is debrided with use of a 4-0 shaver and then prepared for arthrodesis arthroscopically with use of an osteotome and a burr. Next, we inject allograft demineralized matrix-based bone putty under direct arthroscopic visualization to fill residual gaps or defects. The arthrodesis is performed under fluoroscopic guidance with use of 2 guidewires followed by 2 to 3 titanium compression screws. The first screw is inserted along the posteromedial calcaneus and into the talar dome medially. The second is placed laterally into the head-neck junction of the talus. The third screw is placed distal to proximal from the plantar anterior process to the talar head. Finally, images are obtained in multiple views to ensure proper screw placement, and the screws are tightened sequentially to ensure equal compression across the joint. Alternatives: Nonoperative treatment of calcaneal fractures includes cast immobilization with non-weight-bearing, although this treatment is typically reserved for nondisplaced, small extra-articular fractures6. Operative treatment of calcaneal fractures includes open reduction and internal fixation, which is traditionally performed via a sinus tarsi approach or extensile lateral approach. Primary subtalar arthrodesis has been utilized primarily for Sanders type-IV fractures6. Rationale: Displaced intra-articular calcaneal fractures are associated with alarmingly high rates of posttraumatic arthritis (30% to 70% within 1 year of injury), and surgical outcomes are inversely proportional to the severity of the fracture pattern, with Sanders III and IV having the worst outcomes1. Treating these most severe fracture patterns with primary open subtalar arthrodesis has shown favorable results in terms of union rates, pain scores, and functional outcomes throughout the literature2,3. However, some authors have reported rates of revision as high as 60%4. Thus, the PASTA procedure has been established, resulting in significantly better time to union, return to work, activities of daily living, and sports activities compared with open techniques5. Thus, given the favorable results of primary open subtalar arthrodesis and the proven results with use of an arthroscopic technique in the non-acute setting, we propose that C-PASTA can serve as an alternative treatment option in the acute setting for patients with Sanders type-III and IV calcaneal fractures. Expected Outcomes: We expect the outcomes of this procedure to mirror those found throughout the literature, which shows favorable results for open primary subtalar arthrodesis1-3. With use of an arthroscopic approach, we expect better time to union, return to work, activities of daily living, and sports activities than if the procedure were performed in an open fashion5. In addition, minimizing soft-tissue damage through an arthroscopic approach may decrease the risk of infection and stimulate postoperative healing, perhaps accounting for the more favorable postoperative recovery period compared with an open procedure. Important Tips: In the arthroscopic approach to the subtalar joint, identify the flexor hallucis longus, making sure to stay lateral to that tendon to remain in the "safe zone."Utilizing the TRIMANO device (Arthrex) to distract the ankle longitudinally in addition to a solid bump placed on the anterior aspect of the ankle allows for optimal subtalar joint visualization.Fish-scaling with an osteotome followed by bone grafting allows for a good fill between cancellous fragments to stimulate an optimal environment for fusion.Divergent screws should be placed and tightened sequentially to ensure equal compression across the joint. Abbreviations and Acronyms: ADL's = activities of daily livingCT = computed tomographySCD = sequential compression deviceAP = anteroposteriorDVT = deep vein thrombosisBID = twice dailyVit = vitamin.

Mortality from leukemia, cancer and heart disease among U.S. nuclear power plant workers, 1957-2011.

BACKGROUND: The aim of the Million Person Study of Low-Dose Health Effects (MPS) is to examine the level of radiation risk for chronic exposures received gradually over time and not acutely as was the case for the Japanese atomic bomb survivors. Nuclear power plant (NPP) workers comprise nearly 15 percent of the MPS. Leukemia, selected cancers, Parkinson's disease, ischemic heart disease (IHD) and other causes of death are evaluated. METHODS AND MATERIAL: The U.S. Nuclear Regulatory Commission's Radiation Exposure Information and Reporting System (REIRS) and the Landauer, Inc. dosimetry databases identified 135,193 NPP workers first monitored 1957-1984. Annual personal dose equivalents [Hp(10)] were available for each worker. Radiation records from all places of employment were sought. Vital status was determined through 2011. Mean absorbed doses to red bone marrow (RBM), esophagus, lung, colon, brain and heart were estimated by adjusting the recorded Hp(10) for each worker by scaling factors, accounting for exposure geometry and energy of the incident gamma radiation. Standardized mortality ratios (SMR) were calculated. Radiation risks were estimated using Cox proportional hazards models. RESULTS: Nearly 50% of workers were employed for more than 20 years. The mean duration of follow-up was 30.2 y. Overall, 29,124 total deaths occurred, 296 from leukemia other than chronic lymphocytic leukemia (CLL), 3382 from lung cancer, 140 from Parkinson's disease and 5410 from IHD. The mean dose to RBM was 37.9 mGy (maximum 1.0 Gy; percent >100 mGy was 9.2%), 43.2 mGy to lung, 43.7 mGy to colon, 33.2 mGy to brain, and 43.9 mGy to heart. The SMRs (95% CI) were 1.06 (0.94; 1.19) for leukemia other than CLL, 1.10 (1.07; 1.14) for lung cancer, 0.90 (0.76; 1.06) for Parkinson's disease, and 0.80 (0.78; 0.82) for IHD. The excess relative risk (ERR) per 100 mGy for leukemia other than CLL was 0.15 (90% CI -0.001; 0.31). For all solid cancers the ERR per 100 mGy (95% CI) was 0.01 (-0.03; 0.05), for lung cancer -0.04 (-0.11; 0.02), for Parkinson's disease 0.24 (-0.02; 0.50), and for IHD -0.01 (-0.06; 0.04). CONCLUSION: Prolonged exposure to radiation increased the risk of leukemia other than CLL among NPP workers. There was little evidence for a radiation association for all solid cancers, lung cancer or ischemic heart disease. Increased precision will be forthcoming as the different cohorts within the MPS are combined, such as industrial radiographers and medical radiation workers who were assembled and evaluated in like manner.

Dosimetry and uncertainty approaches for the million person study of low-dose radiation health effects: overview of the recommendations in NCRP Report No. 178.

PURPOSE: Scientific Committee 6-9 was established by the National Council on Radiation Protection and Measurements (NCRP), charged to provide guidance in the derivation of organ doses and their uncertainty, and produced a report, NCRP Report No. 178, Deriving Organ Doses and their Uncertainty for Epidemiologic Studies with a focus on the Million Person Study of Low-Dose Radiation Health Effects (MPS). This review summarizes the conclusions and recommendations of NCRP Report No. 178, with a concentration on and overview of the dosimetry and uncertainty approaches for the cohorts in the MPS, along with guidelines regarding the essential approaches used to estimate organ doses and their uncertainties (from external and internal sources) within the framework of an epidemiologic study. CONCLUSIONS: The success of the MPS is tied to the validity of the dose reconstruction approaches to provide realistic estimates of organ-specific radiation absorbed doses that are as accurate and precise as possible and to properly evaluate their accompanying uncertainties. The dosimetry aspects for the MPS are challenging in that they address diverse exposure scenarios for diverse occupational groups being studied over a period of up to 70 y. Specific dosimetric reconstruction issues differ among the varied exposed populations that are considered: atomic veterans, U.S. Department of Energy workers exposed to both penetrating radiation and intakes of radionuclides, nuclear power plant workers, medical radiation workers, and industrial radiographers. While a major source of radiation exposure to the study population comes from external gamma- or x-ray sources, for some of the study groups, there is also a meaningful component of radionuclide intakes that requires internal radiation dosimetry assessments.

A million persons, a million dreams: a vision for a national center of radiation epidemiology and biology.

BACKGROUND: Epidemiologic studies of radiation-exposed populations form the basis for human safety standards. They also help shape public health policy and evidence-based health practices by identifying and quantifying health risks of exposure in defined populations. For more than a century, epidemiologists have studied the consequences of radiation exposures, yet the health effects of low levels delivered at a low-dose rate remain equivocal. MATERIALS AND METHODS: The Million Person Study (MPS) of U.S. Radiation Workers and Veterans was designed to examine health effects following chronic exposures in contrast with brief exposures as experienced by the Japanese atomic bomb survivors. Radiation associations for rare cancers, intakes of radionuclides, and differences between men and women are being evaluated, as well as noncancers such as cardiovascular disease and conditions such as dementia and cognitive function. The first international symposium, held November 6, 2020, provided a broad overview of the MPS. Representatives from four U.S. government agencies addressed the importance of this research for their respective missions: U.S. Department of Energy (DOE), the Centers for Disease Control and Prevention (CDC), the U.S. Department of Defense (DOD), and the National Aeronautics and Space Administration (NASA). The major components of the MPS were discussed and recent findings summarized. The importance of radiation dosimetry, an essential feature of each MPS investigation, was emphasized. RESULTS: The seven components of the MPS are DOE workers, nuclear weapons test participants, nuclear power plant workers, industrial radiographers, medical radiation workers, nuclear submariners, other U.S. Navy personnel, and radium dial painters. The MPS cohorts include tens of thousands of workers with elevated intakes of alpha particle emitters for which organ-specific doses are determined. Findings to date for chronic radiation exposure suggest that leukemia risk is lower than after acute exposure; lung cancer risk is much lower and there is little difference in risks between men and women; an increase in ischemic heart disease is yet to be seen; esophageal cancer is frequently elevated but not myelodysplastic syndrome; and Parkinson's disease may be associated with radiation exposure. CONCLUSIONS: The MPS has provided provocative insights into the possible range of health effects following low-level chronic radiation exposure. When the 34 MPS cohorts are completed and combined, a powerful evaluation of radiation-effects will be possible. This final article in the MPS special issue summarizes the findings to date and the possibilities for the future. A National Center for Radiation Epidemiology and Biology is envisioned.

Progression and stop organization reveals conservation of movement organization during dark exploration across rats and mice.

Spatial orientation is a ubiquitous feature of animal behavior. Environmental and self-movement cues are sources of information used to maintain spatial orientation. The literature has typically focused on differences between mice and rats using environmental cues to guide movement. The current study uses the organization of exploratory behavior under dark conditions to investigate species differences in self-movement cue processing. Mouse and rat exploratory behavior was recorded under dark conditions on a circular table without walls. The resulting movements were segmented in progressions (movement ≥ 3 cm/s) and stops (movement < 3 cm/s). Mice exhibited longer travel distances, faster progression peak speeds, and weaker tendency to scale progression peak speeds to Euclidean distances relative to rats. In contrast, similar levels of performance were observed on measures (progression path circuity, change in heading, stability of stopping behavior) sensitive to vestibular pathology. These results are consistent with species differences in a variety of performance variables; however, self-movement cue based spatial orientation did not differentiate between mice and rats. This work establishes a translational foundation for future work investigating the neurobiology of self-movement cue processing using species-unique neuroscience techniques.

Estimating historical radiation doses to a cohort of U.S. radiologic technologists.

Data have been collected and physical and statistical models have been constructed to estimate unknown occupational radiation doses among 90,000 members of the U.S. Radiologic Technologists cohort who responded to a baseline questionnaire during the mid-1980s. Since the availability of radiation dose data differed by calendar period, different models were developed and applied for years worked before 1960, 1960- 1976 and 1977-1984. The dose estimation used available film-badge measurements (approximately 350,000) for individual cohort members, information provided by the technologists on their work history and protection practices, and measurement and other data derived from the literature. The dosimetry model estimates annual and cumulative occupational badge doses (personal dose equivalent) for each technologist for each year worked from 1916 through 1984 as well as absorbed doses to organs and tissues including bone marrow, female breast, thyroid, ovary, testes, lung and skin. Assumptions have been made about critical variables including average energy of X rays, use of protective aprons, position of film badges, and minimum detectable doses. Uncertainty of badge and organ doses was characterized for each year of each technologist's working career. Monte Carlo methods were used to generate estimates of cumulative organ doses for preliminary cancer risk analyses. The models and predictions presented here, while continuing to be modified and improved, represent one of the most comprehensive dose reconstructions undertaken to date for a large cohort of medical radiation workers.

A comprehensive dose reconstruction methodology for former rocketdyne/atomics international radiation workers.

Incomplete radiation exposure histories, inadequate treatment of internally deposited radionuclides, and failure to account for neutron exposures can be important uncertainties in epidemiologic studies of radiation workers. Organ-specific doses from lifetime occupational exposures and radionuclide intakes were estimated for an epidemiologic study of 5,801 Rocketdyne/Atomics International (AI) radiation workers engaged in nuclear technologies between 1948 and 1999. The entire workforce of 46,970 Rocketdyne/AI employees was identified from 35,042 Kardex work histories cards, 26,136 electronic personnel listings, and 14,189 radiation folders containing individual exposure histories. To obtain prior and subsequent occupational exposure information, the roster of all workers was matched against nationwide dosimetry files from the Department of Energy, the Nuclear Regulatory Commission, the Landauer dosimetry company, the U.S. Army, and the U.S. Air Force. Dosimetry files of other worker studies were also accessed. Computation of organ doses from radionuclide intakes was complicated by the diversity of bioassay data collected over a 40-y period (urine and fecal samples, lung counts, whole-body counts, nasal smears, and wound and incident reports) and the variety of radionuclides with documented intake including isotopes of uranium, plutonium, americium, calcium, cesium, cerium, zirconium, thorium, polonium, promethium, iodine, zinc, strontium, and hydrogen (tritium). Over 30,000 individual bioassay measurements, recorded on 11 different bioassay forms, were abstracted. The bioassay data were evaluated using ICRP biokinetic models recommended in current or upcoming ICRP documents (modified for one inhaled material to reflect site-specific information) to estimate annual doses for 16 organs or tissues taking into account time of exposure, type of radionuclide, and excretion patterns. Detailed internal exposure scenarios were developed and annual internal doses were derived on a case-by-case basis for workers with committed equivalent doses indicated by screening criteria to be greater than 10 mSv to the organ with the highest internal dose. Overall, 5,801 workers were monitored for radiation at Rocketdyne/AI: 5,743 for external exposure and 2,232 for internal intakes of radionuclides; 41,169 workers were not monitored for radiation. The mean cumulative external dose based on Rocketdyne/AI records alone was 10.0 mSv, and the dose distribution was highly skewed with most workers experiencing low cumulative doses and only a few with high doses (maximum 500 mSv). Only 45 workers received greater than 200 mSv while employed at Rocketdyne/AI. However, nearly 32% (or 1,833) of the Rocketdyne/AI workers had been monitored for radiation at other nuclear facilities and incorporation of these doses increased the mean dose to 13.5 mSv (maximum 1,005 mSv) and the number of workers with >200 mSv to 69. For a small number of workers (n=292), lung doses from internal radionuclide intakes were relatively high (mean 106 mSv; maximum 3,560 mSv) and increased the overall population mean dose to 19.0 mSv and the number of workers with lung dose>200 mSv to 109. Nearly 10% of the radiation workers (584) were monitored for neutron exposures (mean 1.2 mSv) at Rocketdyne/AI, and another 2% were monitored for neutron exposures elsewhere. Interestingly, 1,477 workers not monitored for radiation at Rocketdyne/AI (3.6%) were found to have worn dosimeters at other nuclear facilities (mean external dose of 2.6 mSv, maximum 188 mSv). Without considering all sources of occupational exposure, an incorrect characterization of worker exposure would have occurred with the potential to bias epidemiologic results. For these pioneering workers in the nuclear industry, 26.5% of their total occupational dose (collective dose) was received at other facilities both prior to and after employment at Rocketdyne/AI. In addition, a small number of workers monitored for internal radionuclides contributed disproportionately to the number of workers with high lung doses. Although nearly 12% of radiation workers had been monitored for neutron exposures during their career, the cumulative dose levels were small in comparison with other external and internal exposure. Risk estimates based on nuclear worker data must be interpreted cautiously if internally deposited radionuclides and occupational doses received elsewhere are not considered.

Confocal fluorescent imaging of tracks from heavy charged particles utilising new Al2O3:C,Mg crystals.

A completely optical, non-destructive imaging of tracks in a fluorescent crystal provides a new way to detect and to assess doses from heavy charged particles and neutrons. The technique combines confocal fluorescent microscopy with a new radiation-sensitive, luminescent material based on aluminium oxide single crystals doped with carbon, magnesium and having aggregate oxygen vacancy defects (Al2O3:C,Mg). Radiation-induced colour centres in the new material have an absorption band at 620 nm and produce fluorescence at 750 nm with a high quantum yield and a short, 75 +/- 5 ns, fluorescence lifetime. Three-dimensional spatial distribution of fluorescent intensity allows one to obtain depth-dose distributions and to discriminate between high- and low-linear energy transfer radiations. Images of single tracks produced by different types of radiation have been obtained. Irradiations with a calibrated 241Am alpha source showed high efficiency for track detection. Thermal neutrons were detected using a nuclear reaction with a 6LiF radiator and production of alpha particles and tritium ions. Fast neutrons were detected using recoil protons produced in a polyethylene radiator installed in front of the crystalline detector. Three-dimensional reconstruction of a recoil proton propagating through the crystal was demonstrated.

A REVIEW OF TWO METHODS USED IN THE USA TO ASSESS HE DURING FLUOROSCOPIC-BASED RADIOLOGY.

Dosemeter results for ∼81 500 people performing fluoroscopic and interventional radiology procedures were examined to identify differences between groups monitored either by using two dosemeters, one placed at the collar above the apron and a second placed under the apron on the torso (EDE1) or by using one single dosemeter placed at the collar above the apron (EDE2). The median annual HE was 0.17 mSv for those monitored using the EDE1 protocol and 0.26 mSv for the group using the EDE2 protocol. The EDE2 method was used most frequently with the EDE1 method preferred for those more highly exposed. Approximately, 22 % of dosemeter results for EDE1 were inconsistent with expected norms based on over and under apron dosemeter relationships.

Neurons in the lateral agranular frontal cortex have divided attention correlates in a simultaneous temporal processing task.

The frontal cortex is an important brain area for divided attention. Lesions of the lateral agranular frontal cortex in rats disrupt divided attention in a simultaneous temporal processing task. In the present study, the activity of lateral agranular neurons was examined while rats performed a simultaneous temporal processing procedure. Rats were trained to time two stimuli (a light and a tone), each associated with a different fixed interval. Simple trials, in which a single stimulus was presented, and compound trials, in which both stimuli were presented simultaneously, occurred randomly in a session. Rats were able to divide attention between the two stimuli, as assessed by the pattern of lever presses. Approximately 50% of lateral agranular neurons responded to at least one phase of the task with four response patterns observed. The activity of type 1 cells (60%) was altered to compound, but not simple, stimuli. Type 2 cells (10%) responded to both types of simple stimuli and to compound stimuli. Type 3 cells (27%) had changes in firing rate to one type of simple stimulus and to compound stimuli. Type 4 cells (3%) responded to one type of simple stimulus, but were unresponsive to all other stimuli. The large proportion of type 1 cells supports the hypothesis that the lateral agranular cortex is important in divided attention. Previous studies have suggested that the lateral agranular cortex in rats is equivalent to the primary motor cortex. If so, the results from the present study provide evidence that the lateral agranular cortex may have some cognitive functions, in addition to being part of the motor system.

Extraction of cloransulam-methyl from soil with subcritical water and supercritical CO2.

Cloransulam-methyl was extracted from soil samples with supercritical CO2, subcritical water and conventional organic solvents. Supercritical CO2 was less efficient than conventional organic solvents; polarity modifiers had no impact on extraction efficiency. Extraction with supercritical CO2 exhibited a strong temperature dependence. Water was as effective as strong organic solvents for the extraction of cloransulam-methyl; however cloransulam-methyl hydrolyzed when extracted at 150 degrees C. Extraction temperature was the most important variable in increasing the efficiency and rate of extraction, while extraction pressure was not a significant variable.

Are people willing and able to pay for health services?

Following a nationwide increase in user fees for health services in Swaziland, this paper analyzes the effect of the fee increase on overall patient use of health services, on which types of services, curative vs preventive, were most affected, and on changes in utilization by higher paying and lower paying groups. Patient attendance data from a 71% sample of government and mission health facilities, suggests that the 'people are willing and able to pay for health services' assertion is not supported by the Swaziland case. Following the fee increase, average attendance decreased at government facilities by 32.4%, increased at mission facilities by 10.2%, leading to a combined decline of approx. 17%. Patient visits designed to protect against childhood diseases, BCG and DPT immunizations, or against dehydration in children, show average attendance declines of -16, -19, and -24%, respectively, while visits for musculoskeletal diseases, a less serious disease, declined 1.2%. The analysis also suggests that up to 34% of the overall decline in attendance was among patients who previously had paid the least for health care with part of this decline likely including fewer multiple visits.

Photolytic degradation of florasulam on soil and in water.

The rate and pathway of degradation in the presence of light for the triazolopyrimidine herbicide florasulam was determined on soil and in aqueous systems. Florasulam was exposed to natural sunlight for up to 32 days; solar irradiance was measured with either chemical actinometers or by radiometry. The quantum yield for direct photodegradation in a sterile, buffered aqueous solution was determined to be 0.096; an analogous quantum yield for the sum of direct and indirect photodegradation on soil was 0.245. The quantum yields were used to estimate half-lives due to photodegradation as a function of season and temperature. Estimated half-lives due to photodegradation in summer at 40 degrees N latitude were 14 days on soil and 36 days in sterile, buffered water. Photodegradation was much faster in a natural water system, with a measured half-life of 3.3 days in summer at 51.5 degrees N latitude, indicating that indirect photolytic processes will be important contributors to photodegradation of florasulam in aqueous environments.

Aerobic metabolism of diclosulam on U.S. and South American soils.

Degradation of the sulfonanilide herbicide diclosulam was studied on nine soils from three countries to determine the rates and products of aerobic metabolism. Diclosulam was applied to four agricultural soils from the United States, three from Argentina, and two from Brazil at a rate of 0.1 ppm, equivalent to approximately twice the maximum field application rate of 52 g of active ingredient/ha. U.S. and Brazilian soils were incubated in the dark at 25 degrees C at 75% 0.3 bar moisture; Argentinean soils were incubated in the dark at 20 degrees C and 45% moisture holding capacity. Samples were analyzed up to one year after treatment. Two-compartment DT(50) and DT(90) values averaged 28 +/- 12 and 190 +/- 91 days, respectively. Three soil metabolites reached levels of >10% of applied in at least one soil and were identified as the 5-hydroxy analogue of diclosulam (5-OH-diclosulam), aminosulfonyl triazolopyrimidine (ASTP), and the 8-chloro-5-hydroxy analogue of diclosulam (8-Cl-diclosulam). The terminal products of diclosulam soil metabolism were mineralization to CO(2) and bound soil residues. Apparent sorption coefficients (K(d)) were determined on a subset of samples by extraction with a 0. 01 M CaCl(2) solution followed by an acidified acetone extraction. Initial sorption coefficients were similar to those obtained in a batch equilibrium study and averaged 1.1 L/kg for the six soils tested. K(d) coefficients for the metabolites, when available, tended to be slightly lower than that for diclosulam. Sorptivity of diclosulam and degradates increased with time.

Nonresonant beat-wave excitation of relativistic plasma waves with constant phase velocity for charged-particle acceleration.

The nonresonant beat-wave excitation of relativistic plasma waves is studied in two-dimensional simulations and experiments. It is shown through simulations that, as opposed to the resonant case, the accelerating electric fields associated with the nonresonant plasmons are always in phase with the beat-pattern of the laser pulse. The excitation of such nonresonant relativistic plasma waves is shown to be possible for plasma densities as high as 14 times the resonant density. The density fluctuations and the fields associated with these waves have significant magnitudes, facts confirmed experimentally using collinear Thomson scattering and electron injection, respectively. The applicability of these results towards eventual phase-locked acceleration of prebunched and externally injected electrons is discussed.

Growth and reproductive performance of ewe lambs fed corn or soybean meal while grazing pasture.

In a 2-yr study a total of 120 Suffolk and Suffolk-cross ewe lambs, approximately 3 mo of age, were assigned within weight strata to one of three treatments: 1) control, pasture only (C), 2) .09 kg soybean meal/(hd.d) (SBM) plus pasture or 3) .45 kg whole shelled corn/(hd.) plus pasture to compare growth and reproductive performance and to determine lamb selectivity of forage quality and type. Each year, supplements were offered from June through the 3rd wk in November. Ewe lambs were managed as one flock on Kentucky bluegrass (Poa pratensis L.) and tall fescue (Festuca arundinacea Schreb.) pastures except for a brief daily supplementation period when all lambs were brought into a corral and sorted into treatment groups for the feeding. Ewe lambs were exposed to fertile rams from October 1 through the 3rd wk of November each year. Growth rates of ewe lambs grazing pasture alone were slower than those of corn-supplemented ewe lambs and were comparable to those of SBM-supplemented ewe lambs, but reproductive performances were similar (P greater than .05). Date of first detected rise in serum concentrations of progesterone and date of first observed estrus and lambing performance were similar (P greater than .05) among treatments for each year. Compared to hand-clipped forage, forage samples collected by esophageally fistulated lambs were higher (P less than .05) in crude protein and lower (P less than .05) in acid detergent fiber each year, indicating that lambs selectively grazed higher-quality forage. These data indicate that neither protein nor energy limited growth or reproductive performance of these ewe lambs.