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At least 55 records · Page 3Linked to original sources
PubMed1975

A transverse loading system applied to a modified Harrington instrumentation.

Observations using standard Harrington Instrumentation revealed that while maximal distractive forces are applied it is possible to produce further correction of spinal deformity by applying a lateral force. Modifications to the standard Harrington Instrumentation by applying a transverse loading system have been made in order to produce this added correction. The transverse load is applied as nearly as possible in the same plane as the bearing points of hooks, i.e., below the axis of the rods. Transverse loading helps to reduce the distance from the apex of the curve to the midline, thereby producing a more stable spine as well as providing additional support on the convex side. The system is ideal for flexible curves with little kyphosis. Photogrammetry reveals that there was no significant rotation occurring after the application of the transverse load. To date, Instrumentation has been used in 10 patients with success.

Adolescent↗
PubMed1992

The computer synthesis of expressive faces.

This paper presents a methodology for the computer synthesis of realistic faces capable of expressive articulations. A sophisticated three-dimensional model of the human face is developed that incorporates a physical model of facial tissue with an anatomical model of facial muscles. The tissue and muscle models are generic, in that their structures are independent of specific facial geometries. To synthesize specific faces, these models are automatically mapped onto geometrically accurate polygonal facial representations constructed by photogrammetry of stereo facial images or by non-uniform meshing of detailed facial topographies acquired by using range sensors. The methodology offers superior realism by utilizing physical modelling to emulate complex tissue deformations in response to coordinated facial muscle activity. To provide realistic muscle actions to the face model, a performance driven animation technique is developed which estimates the dynamic contractions of a performer's facial muscles from video imagery.

Computer Graphics↗
PubMed1976

The effect of oral physiotherapy on dilantin gingival hyperplasia.

Gingival hyperplasia was studied in 13 boys with epilepsy living in a state hospital. Boys were selected on the basis of having gingival hyperplasia, having all teeth between cuspids (upper and lower), having no occlusal abnormality and being cooperative. After gingivectomy, regrowth of gingiva was compared around lateral incisors on one side of the mouth having operator-assisted oral hygiene with that around lateral incisors on the other side of the mouth without operator-assisted oral hygiene. Regrowth of tissue was documented by precise photogrammetry. Oral hygiene, gingival inflammation and crevicular fluid were monitored. Less inflammation, less crevicular fluid and less regrowth of gingival tissues occurred around teeth subjected to good oral hygiene. Precise periodic photographic documentation of the clinical status of patients during studies such as this is considered very valuable.

Adolescent↗
PubMedDate not supplied

The PAR Technology Corneal Topography System.

BACKGROUND: Computer-assisted videokeratography has emerged as a useful clinical and research tool. All of the currently available commercial units utilize a modified placido disk image and require a smooth reflective surface. The PAR Technology Corneal Topography System (PAR CTS) is a prototype of a new computer-assisted corneal imaging device. The system produces a true topographic map (elevation map) by analyzing a projected grid on the corneal surface, as opposed to a placido disk reflection, and utilizes the technique of raster photogrammetry to define elevation points on the corneal surface. Because the system defines elevation points, not curvature, mathematical modeling is easily accomplished. Current software displays include a true topographic map, a spherical subtraction map in both relative and absolute scales, and a meridian analysis that is adapted to display refractive photoablative surgery. METHODS: We evaluated the accuracy of this device by analyzing three calibrated test spheres (55.76, 42.21, and 33.55 diopters). The test spheres were steel balls coated with a thin white silicone polyester coating that was necessary for grid projection. The test spheres were measured by a Taylor-Hobson contact profilometer possessing submicron accuracy. To determine the reproducibility of the system, three investigators measured three noncalibrated balls (20 mm, 18 mm, and 12 mm). The optical system was purposely decentered and refocused after each reading. RESULTS: Utilizing the CTS custom optics, system accuracy at the 8-millimeter test area was 0.03 (SD 0.03), 0.00, (SD 0.02), and 0.07 (SD 0.01) D respectively. Smaller diameter test areas resulted in a predicted loss of accuracy. Maximum intraobserver variability was 0.09, 0.06, and 0.11 D respectively, and maximum interobserver variability measured 0.18, 0.12, and 0.16 D. CONCLUSIONS: These data demonstrate that the PAR CTS is both highly accurate and reproducible in determining topography of spheres that approximate the curvature of the human cornea.

Algorithms↗
PubMedDate not supplied

Wear measurements in clinical studies of composite resin restorations in the posterior region: a review.

During the last twenty years, wear-evaluation methods have changed, with newer techniques developed to determine the extent of loss of material in posterior composite resin restorations functioning in the mouth. These included: direct clinical evaluation; marginal evaluation on models; heights of exposed cavity walls; volumetric assessment of impressions; profilometry and artificial or natural references; section measurements; coordinate measuring device, contact and noncontact scanning; measuring microscope; photogrammetry; moiré topography; laser interferometry; scanning electron microscopy; and optical scanning. A laser scanning technique appears to hold great potential in clinical research.

Bicuspid↗
PubMed1990

Breast form changes resulting from a certain brassière.

Eleven adult female subjects aged 22-39 years wore a certain brassière for 3 months while anthropometry and moiré fringe photographs on the anterior trunk were taken regularly once a week. After the 3 months, the brassière was not worn for another 3 months. Then the measurements and photogrammetry were repeated for comparison using superimposed moiré configurations. The results are summarized as follows. Regardless of slim or obese trunk, subjects with pendent breasts showed the highest degree of breast form "correction" from wearing the brassière. In all subjects, after 3 months of brassière constraint, the underbust circumference was smaller but the chest circumference became enlarged, the distance between the right and left nipples became wider, and the breasts tended to hang down. This change was more marked in obese subjects with pendent breasts. And when this type of subject wore a "well-fitted" brassière for a long time, her breast form became developed; that is, her breasts hung down more.

Adaptation, Physiological↗
PubMed1990

[The spread of the backspray under different working conditions].

The use of high- and highest-speed preparation instruments and the therefore required intensive spray cooling results not only in more efficient working possibilities but also in an increased infection hazard, especially for the dentist and his assistance caused by the spray rebound. Simulated preparations were carried out on different tooth surfaces at different positions of the patient with or without exhaust under clinical conditions to objectify the space spreading of the spray rebound. The arrangement of the equipment has been objectified by photogrammetry so that the measurement data could be clearly classified. The use of the spraying mist exhaust reduces the spray rebound between 50 and 65%.

Aerosols↗
PubMed1978

Multiple-slit illumination of the optic disc.

A modification to a photo slit-lamp illuminator adds detail to the human optic disc surface by projecting onto it a pattern of fine parallel lines. These stripes curve as they traverse the disc, and its surface contour is revealed. Application of this technique may improve the reliability of methods used to quantitate disc topography.

Evaluation Studies as Topic↗
PubMed1978

Classification of human cataracts.

A stereoscopic system of lens photography was developed and was applied in the classification of different forms of cataract. Lenses, after surgical extraction, can be classified by a technician, independent of ophthalmological collaboration. This system meets the needs of the laboratory scientist and has been adopted by the Cooperative Cataract Research Group.

Cataract↗
PubMed1979

Optic disc parameters and onset of glaucomatous field loss. I. Methods and progressive changes in disc morphology.

Serial stereoscopic fundus photographs taken in known relationship to the onset of glaucomatous visual field loss on 12 eyes were intermixed with those from 206 age- and race-matched controls and analyzed in randomized masked fashion. Progressive changes in the size, shape, or contour of the disc, and a newly described parameter, thickness of the nerve fiber layer as it crosses the disc rim, were readily apparent by the time of onset of glaucomatous field loss in all but two abnormal eyes (one case). In the latter instance, direct comparison of stereophotos indicated progressive pallor of the remaining disc tissue. Serial stereophotographs appear superior to fundus drawings for anticipating glaucomatous field loss.

Glaucoma↗
PubMed1979

Optic disc parameters and onset of glaucomatous field loss. II. Static screening criteria.

Stereoscopic fundus photographs of 17 abnormal eyes, taken in known temporal relationship to the onset of glaucomatous visual field loss, and 206 eyes of age- and race-matched controls were examined in randomized masked fashion. Width of the narrowest remaining disc rim, size of the vertical and horizontal physical cups, contour of the temporal and nasal slopes (vertical ovalness), and a newly described parameter, thickness of the nerve fiber layer as it crosses the disc rim, were all useful for distinguishing patients with impending or established visual field loss. None, however, was as effective as defects in the nerve fiber layer, the only parameter displaying sufficient promise as a clinical screening tool to warrant initiation of large-scale prospective evaluation.

Glaucoma↗
PubMed1979

Contour analysis in plastic and reconstructive surgery.

Three-dimensional measurements of living objects may be made using various biostereometric techniques. Moire topography provides one-step contour line maps. It is a potential low-cost adjuvant to current photographic and cephalometric techniques for documentation of surface deformities. A relatively simple apparatus may be used with instant-processing film to produce immediate contour maps superimposed on the object image on the film. There is significant qualitative information highlighted by the fine resolution of the system. This immediate had data may be quantitatively analyzed by hand with ruler and/or caliper. In the future, off-line quantitative analysis may be made by computer. Geometric constraints of the system and examples of use of the technique are provided. Emphasis is placed on facial asymmetries that are difficult to analyze from plain photographs and inaccessible to data analysis from lateral cephalometric roentgenographs.

Adolescent↗
PubMed1990

Variability of measurements of cranial growth in the rabbit.

This study concerns techniques used in experimental cranial growth research: roentgen cephalometry, roentgen stereophotogrammetry, and gross measurements (osteometry). A comparison of the precision of these methods has not been found in the literature. Computation of technical errors is fundamental to the sound evaluation of registered findings, and such a presentation must be obligatory in all biometric reports. We compared the measurement error of roentgen cephalometric and osteometric data with that obtained by roentgen stereophotogrammetry (RSA). RSA demonstrates a superior replicability, and this technique gives possibilities for kinematic and volumetric determinations simultaneously with distance evaluation. Roentgen cephalometry has the advantage of enabling distance and angular measurements between any well-defined skeletal points or lines. This technique, preferably after implantation of bone markers, is a reliable alternative, but optimal results necessitates calculations of the magnification factor for each bone segment involved. Direct osteometry does not contribute additional information, but problems of image magnification are omitted. Preferably, one individual should perform all measurements regardless of the method used. Growth rates and values calculated by one technique cannot be directly transformed to some other approach. In all probability, assessments of distance changes would gain substantially by using one technical approach consistently throughout actual age intervals. The least variable measurements of sutural growth are made for sutures growing primarily in one plane and with substantial growth rates. One must realize that differences among studies may be due to the limitations of, in particular, the cephalometric and osteometric techniques.

Animals↗
PubMed1991

Photogrammetric evaluation in clinical genetics: theoretical considerations and experimental results.

As newer mathematical approaches are applied to the field of clinical genetics accurate methods of craniofacial measurement are increasingly necessary. If photogrammetric techniques are to be used certain theoretical and practical issues must be taken into account. Errors due to projection are particularly important, but systematic and random errors must also be considered. We discuss theoretical aspects of projection errors along with experimental measurements. Systematic errors in excess of 20% were found during simulations of typical clinical conditions, although smaller errors were obtained using techniques practical in a clinical setting. Photogrammetric measurements are potentially valuable in the field of clinical genetics but must be used cautiously.

Cephalometry↗
PubMed1979

Morphology of the atrioventricular node, bundle and proximal bundle branches: a study employing computerized reconstruction.

The morphology of the human atrioventricular node, atrioventricular bundle and bundle branches is described. A block of tissue bounded by the ostium of the coronary sinus, the pars membranacea, the septal leaflet of the tricuspid valve and the atrial and ventricular septa is removed. The block is then sectioned serially from the right endocardial surface in the frontal plane of the heart. Sectioning in this way produces fewer sections than from techniques previously described. Outlines of the atrioventricular node, atrioventricular bundle and proximal bundle branches are digitally registered and stored in a computer. Three dimensional reconstructions of the structures are then generated by computer and displayed on an oscilloscope so that the entire three dimensional image can be rotated in any plane. Stereoscopic image pairs are produced to assist perception of the shape of the atrioventricular node, bundle and branching patterns of the bundles. This technique is unique in that it describes a method from which a relatively small number of histologic sections are generated permitting not only a complete histologic examination, but also a study of the morphology of the area.

Adult↗
PubMed1992

Formation of secretory granules in the Golgi apparatus of prolactin cells in the rat pituitary gland: a stereoscopic study.

The mode of secretory granule formation in prolactin cells was analyzed in thin or thick sections of pituitary glands from non-lactating or lactating female as well as from male rats. In all these animals, the Golgi apparatus of prolacting cells consists of a continuous twisted ribbon-like structure that branches and anastomoses to form a hollow sphere located in the juxtanuclear area. The early signs of secretory granule formation are observed along the trans-aspect of the Golgi ribbon where progranules appear as focal distensions simultaneously occurring anywhere in the last trans thiamine pyrophosphatase (TPPase)-containing Golgi element. In the transmost Golgi saccule, such dilatations usually contain several nodular masses of electron opaque material which are separated from each other and from the saccular membrane by a less intensely stained material. While this transmost saccule becomes more fenestrated, its focal polynodular distensions seemingly yield polynodular tubular progranules which are initially closely apposed and usually parallel to the trans face of the Golgi ribbon. Subsequently, these progranules, which frequently show small membranous tubules or tubular networks attached to them, are seen some distance from the Golgi stacks and progressively transform into the more compact polymorphous granules characteristic of prolactin cells. These observations suggest that the polynodular tubular progranules arise by fragmentation of portions of the trans-Golgi elements rather than by fusion of small uninodular granules budding from the edges of a trans-Golgi saccule. Once the progranules have been liberated, the rest of the transmost Golgi element appears to break down into small residual networks, tubules, and vesicles. Thus, in prolactin cells as in other glandular cells, the whole transmost Golgi element would fragment during formation of prosecretory granules.

Animals↗
PubMed1990

The three-dimensional tracking pattern of the human patella.

A study was undertaken to provide data on the three-dimensional tracking pattern of the patella, relative to the femur, in human knee-joint specimens. For this purpose, a highly accurate roentgen stereophotogrammetric analysis (RSA) method was applied. The three-dimensional motion patterns of the tibia and the patella were measured and represented in terms of three translations and three rotations each, during knee flexion in neutral (unloaded), endorotated, and exorotated pathways. We found that the patella displays complex but consistent three-dimensional motion patterns during flexion, which include flexion rotation, medial rotation, wavering tilt, and a lateral shift relative to the femur. The motion patterns are very much affected by tibial rotations accompanying flexion.

Humans↗