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D Bor

Publications and source records attributed to D Bor.

9 recordsLinked to original sources
PubMed2004

Comparison of effective doses obtained from dose-area product and air kerma measurements in interventional radiology.

In this study, measurements of dose-area product (DAP) and entrance dose were carried out simultaneously in a sample of 162 adult patients who underwent different interventional examinations. Effective doses for each measurement technique were estimated using the conversion factors that have been determined for specific X-ray views in a mathematical phantom. Exposure conditions used in clinical practice never match these theoretical models exactly, and deviations from the assumed standard conditions cause uncertainties in effective dose estimations. Higher effective dose values are found if the air kerma results are used rather than DAP readings, both for patient and Rando phantom studies. Comparison of DAP, fluoroscopy times and skin doses were made with published data. DAP measurement for the effective dose calculation and thermoluminescent dosimeter for the skin dose estimates are found to be the most reliable methods for patient dosimetry.

Adult↗
PubMed2001

The role of spatial configuration in tests of working memory explored with functional neuroimaging.

While the importance of the prefrontal cortex for "higher-order" cognitive functions is largely undisputed, no consensus has been reached regarding the fractionation of functions within this region. Several recent functional neuroimaging studies have suggested that the mid-ventrolateral frontal cortex may play an important role in various aspects of human memory. Thus, similar patterns of activation have been observed in this region during analogous spatial, verbal and visual span tasks. In the present study, however, activation was observed in a more dorsolateral region of the lateral frontal cortex during a modified version of the spatial span task, which differed only in the spatial configuration of the array employed. The results of a supplementary behavioral study, designed to investigate this effect further, suggest that in spatial memory tasks certain stimulus configurations may encourage subjects to adopt mnemonic strategies, which may depend upon dorsolateral, rather than ventrolateral, regions of the frontal cortex. These findings shed further light on the functional relationship between dorsal and ventral regions of the lateral frontal cortex and, more specifically, how the "executive" processes assumed to be dependent upon these regions might contribute to aspects of human memory.

Adult↗
PubMed2000

A neural basis for general intelligence.

Universal positive correlations between different cognitive tests motivate the concept of "general intelligence" or Spearman's g. Here the neural basis for g is investigated by means of positron emission tomography. Spatial, verbal, and perceptuo-motor tasks with high-g involvement are compared with matched low-g control tasks. In contrast to the common view that g reflects a broad sample of major cognitive functions, high-g tasks do not show diffuse recruitment of multiple brain regions. Instead they are associated with selective recruitment of lateral frontal cortex in one or both hemispheres. Despite very different task content in the three high-g-low-g contrasts, lateral frontal recruitment is markedly similar in each case. Many previous experiments have shown these same frontal regions to be recruited by a broad range of different cognitive demands. The results suggest that "general intelligence" derives from a specific frontal system important in the control of diverse forms of behavior.

Adult↗
PubMed2000

A council of elders: creating a multi-voiced dialogue in a community of care.

In an era of 'medical care delivery systems', there is an increasing need for the patient's voice to be heard, for it to be invited, listened to, and taken seriously. This challenge is particularly evident in geriatrics education, a domain of clinical training in which educators and clinicians alike must struggle to overcome adverse attitudes towards the elderly ('ageism'). In this paper we introduce a 'Council of Elders' as an educational innovation in which we invited community elders to function as our 'Senior Faculty', to whom medical residents present their challenging and heartfelt dilemmas in caring for elder patients. In the conversations that ensue, the elders come to function not simply as teachers, but collaborators in a process in which doctors, researchers, and elders together create a community of resources, capable of identifying novel ways to overcome health-related difficulties which might not have been apparent to either group separately. Using the first meeting of the Council as an exemplar, we describe and discuss the special nature of such meetings and also the special preparations required to build a dialogic relationship between participants from very different worlds--different generations, different cultures (including the professional culture and the world of lived experience). Meetings with the council have become a required part of the primary care residency program--a very different kind of 'challenging case conference' in which moral dilemmas can be presented, discussed and reflected upon. It is not so much that elders give good advice in their responses--although they often do--as that they provide life world and value orientation as young residents gain a better sense of the elder's experience and what matters most to them. This project has been particularly worthwhile in addressing the problem of ageism--a way to render visible stereotypes and adverse physician values, with implications for decision-making with the patient, not for the patient.

Aged↗
PubMed2000

Lens of the eye: radiation dose in balloon dacryocystoplasty.

PURPOSE: To evaluate the absorbed radiation dose to the lens of the eye, which is the critical organ in the primary beam during fluoroscopically guided transluminal balloon dilation of the lacrimal drainage system (balloon dacryocystoplasty) for obstructive epiphora and to evaluate the possibility of deterministic radiation effect on the lens. MATERIALS AND METHODS: The radiation dose to the lens of the eye during balloon dacryocystoplasty (which includes pre- and postintervention dacryocystography) was measured in 10 consecutive patients by using thermoluminescent dosimeters on the lids of both eyes as close as possible to the lenses. A C-arm angiographic unit coupled with a digital imaging system was used, with similar exposure and geometric parameters in all cases. RESULTS: The mean radiation dose to the lens of the treated eye was 4.6 mGy +/- 2.2 (dose range, 1.9-9.1 mGy) and to that of the untreated eye was 38.5 mGy +/- 17.5 (dose range, 14.7-67.8 mGy). CONCLUSION: The lens of the untreated eye receives a higher dose than that of the treated eye because of its closer proximity to the x-ray tube in a lateral projection. In the lens, even the highest measured radiation dose (67.8 mGy) still was well below the deterministic threshold for lens opacity and cataract formation.

Adult↗
PubMed1999

Effect of silicone breast implants on myocardial imaging.

The authors investigated the effect of silicone breast implants (SBIs) on thallium-201 myocardial perfusion scintigraphy. Twenty-nine patients with SBIs and 14 control subjects were included in the study. All of the participants underwent a resting thallium-201 myocardial perfusion study. Comparison of the thallium images between patients with SBI and control subjects was done both visually and semiquantitatively. On visual analysis, neither image distortion nor image artifact attributable to the SBIs was noted. Semiquantitative analysis revealed that in patients with SBIs, the uptake values of the anteroseptal, anterolateral, lateroanterior, and lateroinferior myocardial walls was slightly, but significantly, lower than those of control subjects: anteroseptal, 87.7+/-6.0% vs. 92.8+/-5.1%; anterolateral, 88.0+/-5% vs. 92.6+/-4.5%; lateroanterior, 87.4+/-5% vs. 91.4+/-4.7%; and lateroinferior, 86.0+/-6.0% vs. 91.7+/-7.0%. The uptake value of the remaining walls in patients with SBIs were not significantly different than the control subjects. In conclusion, SBIs did cause a significant decrease in uptake values of the myocardial walls, which should be considered during interpretation of the images.

Adult↗
PubMedDate not supplied

Febrile inpatients: house officers' use of blood cultures.

The so-called "fever work-up" is time-consuming and costly. The authors examined the practices of medical house officers in obtaining blood cultures, an important part of this evaluation, as well as the ability of these physicians to predict bacteremia in febrile patients. They studied all 344 medical inpatients who experienced episodes of fever during two 30-day periods, as well as all 50 cases of bacteremia detected during these and two additional 30-day periods. House officers drew blood for culture within one day after the onset of fever in 52% of fever episodes. In 20% of these episodes only one set of cultures (representing one venipuncture) was obtained. House officers estimated the likelihood of bacteremia to be 20% or less in 15 of 40 bacteremic patients. They failed to obtain blood cultures promptly in 10% of bacteremic episodes and in 27% of episodes where the cause of fever was a nonbacteremic bacterial infection. They obtained prompt blood cultures in only a bare majority of febrile episodes, frequently underestimated the likelihood of bacteremia, and inadequately sampled blood for bacteremia. In this study, clinical judgment was not an adequate substitute for routinely obtaining blood cultures for febrile medical inpatients.

Aged↗