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Biomedical subjects

A Mol

Publications and source records attributed to A Mol.

At least 19 recordsLinked to original sources
PubMed2002

Pitfalls in effectiveness research: a comparative analysis of treatment goals and outcome measures in stroke rehabilitation.

PROBLEM: There is a great diversity of movement therapies in stroke rehabilitation, each of which is treated as a more or less independent system. OBJECTIVE: To articulate pitfalls in effectiveness research that has been employed to reduce the number of different forms of treatment. METHODS: The contents of treatment goals and outcome measures in clinical and scientific texts on stroke rehabilitation were analysed and contrasted in order to uncover discrepancies. ISSUES: The main issue is that theory, and conceptualization of therapy play a diminished role in treatment effectiveness research, which may hinder the interpretation of data. The notion that the methodological and statistical tools, if correctly applied, provide researchers with the distance that is thought to be necessary for an objective judgement will be challenged. CONCLUSION: The analyses indicate that although scientifically credible measurement tools may be neutral with regard to the user, they are not necessarily neutral with regard to the therapies being compared in effectiveness research.

Humans↗
PubMed2001

Performance of a new F-speed film for caries detection.

OBJECTIVE: To compare films from three speed groups for the detection of approximal caries. STUDY DESIGN: Insight, Ektaspeed Plus and Ultra-speed (Eastman-Kodak, Rochester, NY, USA) radiographs of the proximal surfaces of 40 extracted posterior teeth were evaluated by six observers. The presence or absence of caries was scored using a 5-point confidence scale. The actual status of each surface was determined from histology of ground sections. Observer responses were evaluated using ROC analysis and areas under the ROC curves (A(Z)) assessed using ANOVA. RESULTS: Ultra-speed film had a mean A(Z) of 0.88, Ektaspeed Plus 0.85, and Insight 0.84. These differences were not statistically significant (P=0.5). Differences between observers were also not statistically significant (P=0.42). CONCLUSIONS: The performance of the new F-speed film was not statistically different from E or D speed for caries detection. This film shows promise as a means of reducing patient dose while maintaining diagnostic quality.

Analysis of Variance↗
PubMed2001

Image-receptor performance: a comparison of Trophy RVG UI sensor and Kodak Ektaspeed Plus film.

UNLABELLED: Objective. This study compares the physical characteristics of the RVG UI sensor (RVG) with Ektaspeed Plus film. STUDY DESIGN: Dose-response curves were generated for film and for each of 6 available RVG modes. An aluminum step-wedge was used to evaluate exposure latitude. Spatial resolution was assessed by using a line-pair test tool. Latitude and resolution were assessed by observers for both modalities. The RVG was further characterized by its modulation transfer function. RESULTS: Exposure latitude was equal for film and RVG in the periodontal mode. Other gray scale modes demonstrated much lower latitude. The average maximum resolution was 15.3 line-pairs per millimeter (lp/mm) for RVG in high-resolution mode, 10.5 lp/mm for RVG in low-resolution mode, and 20 lp/mm for film (P <.0001). Modulation transfer function measurements supported the subjective assessments. CONCLUSIONS: In periodontal mode, the RVG UI sensor demonstrates exposure latitude similar to that of Ektaspeed Plus film. Film images exhibit significantly higher spatial resolution than the RVG images acquired in high-resolution mode.

Analysis of Variance↗
PubMed2001

Characteristics of Kodak Insight, an F-speed intraoral film.

OBJECTIVES: This study reports film speed, contrast, exposure latitude, resolution, and response to processing solution depletion of Kodak Insight intraoral film. METHODS: Densitometric curves were generated by using International Standards Organization protocol. Additional curves were generated for Ultra-speed, Ektaspeed Plus, and Insight films developed in progressively depleted processing solutions. Eight observers viewed images of a resolution test tool for maximum resolution assessment. Images of an aluminum step-wedge were reviewed to determine useful exposure latitude. RESULTS: Insight's sensitivity in fresh automatic processor solutions places it in the F-speed group. An average gradient of 1.8 was found with all film types. Insight provided 93% of the useful exposure latitude of Ektaspeed Plus film. Insight maintained contrast in progressively depleted processing solutions. Like Ektaspeed Plus, Insight was able to resolve at least 20 line-pairs per millimeter. CONCLUSIONS: Under International Standards Organization conditions, Insight required only 77% of the exposure of Ektaspeed Plus film. Insight film provided stable contrast in depleted processing solutions.

Analysis of Variance↗
PubMed2001

Performance of RVGui sensor and Kodak Ektaspeed Plus film for proximal caries detection.

OBJECTIVE: A high-resolution charge-coupled device was used to compare the diagnostic performances obtained with Trophy's new RVGui sensor and Kodak Ektaspeed Plus film with respect to caries detection. STUDY DESIGN: Three acquisition modes of the Trophy RVGui sensor were compared with Kodak Ektaspeed Plus film. Images of the proximal surfaces of 40 extracted posterior teeth were evaluated by 6 observers. The presence or absence of caries was scored by means of a 5-point confidence scale. The actual caries status of each surface was determined through ground-section histology. Responses were evaluated by means of receiver operating characteristic analysis. Areas under receiver operating characteristic curves (A(Z)) were assessed through analysis of variance. RESULTS: The mean A(Z) scores were 0.85 for film, 0.84 for the high-resolution caries mode, and 0.82 for both the low resolution caries mode and the high-resolution periodontal mode. These differences were not statistically significant (P =.70). The differences among observers also were not statistically significant (P =.23). CONCLUSION: The performance of the RVGui sensor in high- and low-resolution modes for proximal caries detection is comparable to that of Ektaspeed Plus film.

Analysis of Variance↗
PubMed2000

What diagnostic devices do: the case of blood sugar measurement.

Diagnostic devices do more than just passively register facts. They intervene in the situations in which they are put to use. The question addressed here is what this general remark may imply in specific cases. To answer this question a specific case is being analysed: that of the blood sugar measurement device that people with diabetes may use to monitor their own blood sugar levels. This device not only allows the patients concerned to better approach normal blood sugar levels, but alters what counts as normal in the first place. Using the device may shift people's attention away from their physical sensations towards the numbers measured, but it may also help them to increase their own physical self-awareness. Self-monitoring finally (something that the devices have made possible) makes patients less dependent on professionals, but it requires them to engage in self-disciplining and binds them to the outcomes of their measurement activities: their own blood sugar levels.

Blood Glucose Self-Monitoring↗
PubMed2000

Image processing tools for dental applications.

Digital image processing has seen a wide variety of applications in dental radiography. Examples of operations from any of the fundamental classes can be found in the literature, and the increasing role of digital technology in dental imaging will promote new developments and clinical applications. Further progress is not limited by a lack of available image processing tools; rather, improvement of our understanding of the various components of diagnostic imaging will facilitate the meaningful use of new imaging technologies in dentistry. Image processing cannot be separated from other aspects of the diagnostic imaging chain. Its diagnostic value fundamentally depends on image acquisition as well as on aspects of vision and cognition. If used properly, image processing can help to improve diagnostic outcomes and provide insight into other aspects of the imaging process that may be limiting the diagnostic yield. Although novelty is still a powerful force driving some scientific endeavors, advances in dental imaging will be based on the purposeful, goal-oriented development and application of new technology. Specifications for useful image processing operations need to be defined with the diagnostic problem in mind as well as the final outcome for the patient.

Humans↗
PubMed1999

Clinical specificity and the non-generalities of science. On innovation strategies for neurological physical therapy.

How to improve clinical practice and, in particular, that of physical therapy? Currently, several strategies are used which all fit the label 'scientification'. These scientific strategies have to make physical therapy's clinical practice more homogeneous. Sometimes this homogenization is thought to be necessary for other strategies of innovation including effectiveness research. But it has also been suggested that more homogeneity in the clinic is already itself an improvement. In this article we comment on these strategies. More specifically, we direct our attention at attempts in physical therapy to establish a uniform, generally adopted scientific language. We argue that these attempts fail to appreciate the specificity of therapeutic work. The effectiveness research that follows is therefore liable to take irrelevant variables into account. We illustrate this argument with examples taken from analyses of diverging therapies for stroke patients.

Activities of Daily Living↗
PubMed1994

Principles and practices of medicine. The co-existence of various anemias.

The medical textbooks in our university library present 'principles' as the basis which underlies medical 'practice'. In this article it is argued that this helps different medical logics to co-exist. The example analyzed is that of anemia in the Netherlands. Currently this is defined pathophysiologically, statistically and clinically. These three definitions are intertwined with different strategies for the creation of normal hemoglobin levels and the detection of patients with anemia. The discrepancies between them, however, do not lead to the controversies that might be expected by those who believe in consistency. Instead, the rhetoric of principles-and-practice helps to bring about peaceful co-existence.

Adult↗
PubMed1994

Regions, networks and fluids: Anaemia and social topology.

This is a paper about the topological presuppositions that frame the performance of social similarity and difference. It argues that 'the social' does not exist as a single spatial type, but rather performs itself in a recursive and topologically heterogeneous manner. Using material drawn from a study of the way in which tropical doctors handle anaemia, it explores three different social topologies. First, there are 'regions' in which objects are clustered together, and boundaries are drawn round each cluster. Second, there are 'networks' in which distance is a function of relations between elements, and difference a matter of relational variety. These two forms of spatiality are often mobilized in social theory. However, we argue that there are other kinds of social space, and here consider the possible character of a third, that of 'fluid spatiality'. In this, places are neither delineated by boundaries, nor linked through stable relations: instead, entities may be similar and dissimilar at different locations within fuid space. In addition, they may transform themselves without creating difference.

Anemia↗
PubMed1993

Radiopacity of posterior composite resins, composite resin luting cements, and glass ionomer lining cements.

The radiopacities of seven posterior composite resins, seven composite resin luting cements, and six glass ionomer lining cements were studied. The purpose was to obtain an indication of radiopacity values of different brands within each of these three groups of materials and to show differences in radiopacities of composite resin inlay materials and their accompanying luting cements. On radiographs, the optical densities of standardized samples were determined and radiopacity values of the materials were expressed in millimeter equivalent aluminum. The composite resins observed displayed higher radiopacities than aluminum. A luting cement and a glass ionomer cement were shown to be less radiopaque than aluminum. Generally the radiopacity of composite resins appeared to be higher than their accompanying luting cements. If materials with substantial differences in radiopacity are used in combined applications for the restorative treatment of teeth, lower radiopacity can interfere with the diagnosis of caries and the detection of gaps near the restoration.

Bicuspid↗
PubMed1993

Locating the periapical region in dental radiographs using digital image analysis.

An algorithm was designed to automatically obtain information on the orientation of roots in dental radiographs aimed at localizing the periapical region. A curve was approximated mathematically by a cubic polynomial to intersect the boundary of the root at its apex. The performance was judged by comparing the location of this intersection with the actual location of the apex as determined by five expert observers. In an experiment with 262 roots of the eight tooth groups, the distance between these two points was less than 1 mm in 67.9% of all cases and less than 2 mm in 88.2%. The performance of the procedure appeared to depend on the tooth group (p < 0.01). The location of the intersection was reproducible within 1 mm in 86.4% of all cases. The reproducibility was, however, not equal for all tooth groups (p < 0.01). The experts were more consistent in localizing the apex than the system was (p < 0.01), although this difference was not confirmed for four of the tooth groups (p > 0.57), and was marginal for two others (0.01 < p < 0.02). It is concluded that the algorithm is promising in its capacity to track a majority of roots down to their apex. It could therefore add important knowledge to imaging procedures aimed at the digital analysis of the periapical region.

Algorithms↗
PubMed1992

Diagnosing periapical bone lesions on radiographs by means of texture analysis.

Trabecular pattern, the radiographic projection of trabecular bone, is a repeated structure that appears in a dental radiograph. Texture analysis, the computer image analysis of repeated patterns, is a technique that can be used to automate the diagnosis of periapical lesions with the detection of the absence of the texture that corresponds to the trabecular bone. The purpose of this study was to determine whether it is feasible to use texture analysis to identify the presence of the trabecular pattern in radiographs and to detect a periapical bone lesion based on a local absence of this pattern. Thirty-two mandibular periapical films, 16 with and 16 without periapical lesions, were used in this study. Texture analysis was carried out on the digital images of these radiographs. In the 16 films with lesions, they were all correctly identified, and no lesions were found in the 16 films without lesions. This result is based on the a prior knowledge of the user about the localization of the disease. Locating periapical regions without user interaction is a goal for future research.

Alveolar Process↗
PubMed1992

The dependence of shrinkage stress reduction on porosity concentration in thin resin layers.

The development of polymerization contraction stress was determined as a function of the surface area of porosity, so that the contribution of voids in resin composite to stress relief could be investigated. Experiments were carried out on 200-microns-thick layers of resin bonded from wall to wall in a restrained condition. The resin samples were divided into three groups: Group A was without porosity, group B contained a small number of pores, and group C contained a large number of pores in comparison with group B. For each group, porosity area, maximal stress, and stress development rate were determined. The mean maximal stress and stress development rate were inversely proportional to the mean porosity surface. These characteristics differed significantly (p less than 0.01) between group A and C. For determination of whether shrinkage stress reduction has to be ascribed to flow from the outer surfaces of the voids or to inhibition of the setting reaction by oxygen in the voids, resin containing only nitrogen bubbles was also tested. The results indicated that both aspects contributed substantially to shrinkage stress relief. Incorporation of pores by the stirring of a luting cement contributes to stress reduction and can therefore be considered as a contribution to the maintenance of marginal integrity.

Analysis of Variance↗
PubMed1992

Application of computer-aided image interpretation to the diagnosis of periapical bone lesions.

An image analysis system was developed for the computer-aided diagnosis of periapical bone lesions in dental radiographs. The system was designed to (1) identify the periapical region, (2) determine the presence of a periapical lesion and (3) estimate the size of the lesion in cases when a lesion had been found. To initiate the procedure, an observer indicates an arbitrary point on the root in a digitized radiograph. From this initial point, the location of the radiographic projection of the apex of the root is automatically computed. Next, the trabecular bone pattern is detected through texture analysis. A local absence of the trabecular bone pattern in the periapical region is marked as a periapical bone lesion. When a lesion has been identified, its size is estimated based on local edge properties. Observer interaction is only allowed to adjust the result of the apex localization procedure if the apex has not correctly been localized. In an experiment with randomly selected radiographs of 111 mandibular roots, the performance of the system was tested against the consensual diagnosis of four expert observers. The sensitivity of the system to identify a lesion was 83.3%, the specificity 75.6% and the diagnostic accuracy 80.2%. The correlation between the size of the lesions as estimated by the system and by the observers was 0.67 (P < 0.01). When the procedure was repeated, the percentage of correctly reproduced lesion sizes by the system was 92.8%. The determination of the presence of a lesion was reproducible in 98.2% of all the cases.

Alveolar Bone Loss↗
PubMed1991

Application of digital image analysis in dental radiography for the description of periapical bone lesions: a preliminary study.

This paper describes an application of digital image analysis for the description of periapical bone lesion in dental radiography. These techniques enable the problem of observer variability to be circumvented, and can eventually be used for the quantitative assessment of bone lesions. Since periapical bone lesions appear radiographically as dark areas compared with their surrounding tissues, an edge-detection method was developed to extract the boundaries between anatomy and pathology. The original data were transformed in such a way that only the outlines remained. The lesion was assumed to be demarcated by a continuous outline, so all the contour points not being part of a continuous outline were excluded. With only limited operator interaction, the lesion contour could be projected successfully onto the original image. The result of this operation was a simplified diagnostic examination process promising a higher degree of objectivity in periapical bone lesion detection. It is concluded that the results encourage further development of image processing techniques suitable for the definitive detection and diagnosis of periapical bone lesions.

Alveolar Bone Loss↗
PubMed1989

Digital image analysis for the diagnosis of periapical bone lesions: a preliminary study.

Digital image analysis techniques enable the problem of examiner variability to be circumvented, and can be used to develop quantitative descriptions of bone lesions. This study investigated a method for describing periapical bone lesions. An edge-detection technique was developed for application to routine periapical radiographs. Most periapical bone lesions appear radiographically as dark areas compared with the surrounding tissues. The digital imaging process resulted in an outline resembling the contour of the image of the lesion present. This contour could be successfully projected on to the original image with only limited operator assistance. Processing of the image resulted in increased definition of the structures present, with considerable noise reduction. The result was a simplified diagnostic examination process that promised a high degree of objectivity in periapical bone lesion detection. It is concluded that the results encourage further development of image processing techniques suitable for the definitive detection and diagnosis of periapical bone lesions.

Image Processing, Computer-Assisted↗