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Results for “Photogrammetry”

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At least 217 records · Page 12Linked to original sources

PubMed2006

Ptosis aggravates dysphagia in oculopharyngeal muscular dystrophy.

BACKGROUND: Ptosis and dysphagia are important features in oculopharyngeal muscular dystrophy (OPMD). OBJECTIVE: Retroflexion of the head is a well known compensatory mechanism for ptosis, but generally retroflexion has a negative effect on swallowing. We hypothesised that severity of ptosis is related to degree of retroflexion and that this compensation is responsible for deteriorating dysphagia. METHODS: Nine OPMD patients were examined in the conditions "head position adapted to ptosis" and "head position slightly flexed". Ptosis was quantified by photogrammetry and retroflexion of the head by digital photographs. The severity of dysphagia was measured using visual analogue scales (VAS) and by calculating swallowing volumes and oropharyngeal swallow efficiency (OPSE) based on videofluoroscopy. RESULTS: Statistical analyses show a significant relationship between ptosis and degree of retroflexion. The degree of retroflexion of the head correlated significantly with VAS scores and with the maximum swallowing volume. The slightly flexed head position significantly improved VAS scores as well as swallowing volumes and OPSE. CONCLUSION: In OPMD patients, ptosis significantly correlates with retroflexion of the head, which has a negative effect on swallowing. Subjective and objective reduction of swallowing problems was found when patients were instructed to eat and drink with a slightly flexed head position.

Adult↗

PubMed2005

[Gait analysis in Parkinson's disease and response to dopaminergic treatment].

BACKGROUND AND OBJECTIVE: The objective of this study was to analyze the gait abnormalities in patients with idiopathic Parkinson's disease (PD), and their response to dopaminergic treatment. PATIENTS AND METHOD: 15 patients and 15 healthy age-matched subjects were included for comparison between pathologic and "normal" gait, and 24 PD patients were included to assess the effects of treatment. Gait analysis was achieved with a new 3D-photogrammetry system. RESULTS: Patients had significative lower velocity, stride length, step length and hip and knee ranges when compared with control subjects. There were no differences in cadence, step width and relative times of gait-cycle. There were no differences in the patients' gait variables after administration of a dopaminergic medication. CONCLUSIONS: Gait analysis allows quantification of gait disturbances in patients with PD and the potential effects of treatment. The results of this study suggest a certain degree of "levodopa-resistance" in gait in these patients.

Dopamine Agents↗

PubMed2005

Geomatics for precise 3D breast imaging.

Canadian women have a one in nine chance of developing breast cancer during their lifetime. Mammography is the most common imaging technology used for breast cancer detection in its earliest stages through screening programs. Clusters of microcalcifications are primary indicators of breast cancer; the shape, size and number may be used to determine whether they are malignant or benign. However, overlapping images of calcifications on a mammogram hinder the classification of the shape and size of each calcification and a misdiagnosis may occur resulting in either an unnecessary biopsy being performed or a necessary biopsy not being performed. The introduction of 3D imaging techniques such as standard photogrammetry may increase the confidence of the radiologist when making his/her diagnosis. In this paper, traditional analytical photogrammetric techniques for the 3D mathematical reconstruction of microcalcifications are presented. The techniques are applied to a specially designed and constructed x-ray transparent Plexiglas phantom (control object). The phantom was embedded with 1.0 mm x-ray opaque lead pellets configured to represent overlapping microcalcifications. Control points on the phantom were determined by standard survey methods and hand measurements. X-ray films were obtained using a LORAD M-III mammography machine. The photogrammetric techniques of relative and absolute orientation were applied to the 2D mammographic films to analytically generate a 3D depth map with an overall accuracy of 0.6 mm. A Bundle Adjustment and the Direct Linear Transform were used to confirm the results.

Breast Neoplasms↗

PubMed2006

Sagittal jaw position in relation to body posture in adult humans--a rasterstereographic study.

BACKGROUND: The correlations between the sagittal jaw position and the cranio-cervical inclination are described in literature. Only few studies focus on the sagittal jaw position and the body posture using valid and objective orthopaedic examination methods. The aim of this study was to test the hypothesis that patients with malocclusions reveal significant differences in body posture compared to those without (upper thoracic inclination, kyphotic angle, lordotic angle and lower lumbar inclination). METHODS: Eighty-four healthy adult patients (with a mean age = 25.6 years and ranging from 16.1 to 55.8 years) were examined with informed consent. The orthodontic examination horizontal overjet (distance between upper and lower incisors) was determined by using an orthodontic digital sliding calliper. The subjects were subdivided in respect of the overjet with the following results: 18 revealed a normal overjet (Class I), 38 had an increased overjet (Class II) and 28 had an reversed overjet (Class III). Rasterstereography was used to carry out a three-dimensional back shape analysis. This method is based on photogrammetry. A three-dimensional shape was produced by analysing the distortion of parallel horizontal white light lines projected on the patient's back, followed by mathematical modelling. On the basis of the sagittal profile the upper thoracic inclination, the thoracic angle, the lordotic angle and the pelvic inclination were determined with a reported accuracy of 2.8 degrees and the correlations to the sagittal jaw position were calculated by means of ANOVA, Scheffé and Kruskal-Wallis procedures. RESULTS: Between the different overjet groups, no statistically significant differences or correlations regarding the analysed back shape parameters could be obtained. However, comparing males and females there were statistically significant differences in view of the parameters 'lordotic angle' and 'pelvic inclination'. CONCLUSION: No correlations between overjet and variables of the thoracic, lordotic or the pelvic inclination could be observed.

Adolescent↗

PubMed2005

Microstrain fields for cortical bone in uniaxial tension: optical analysis method.

This study employed an optical strain measurement method, called microdisplacements by machine vision photogrammetry (DISMAP), to measure both the global and local strain fields in microtensile specimens of cortical bone subjected to controlled uniaxial tension. The variation of local maximum principal strains was measured within the gauge region of samples as a function of applied tensile stress during testing. High gradients of local strain appeared around microstructural features in stressed bone even while the global strain for the entire gauge region showed a strong linear correlation with increasing tensile stress (r2 = 0.98, p < 0.0001). The highest local strain around microstructural features in bone was 11.5-79.5 times higher than the global strain.

Animals↗

PubMed2004

Image aberrations in optical three-dimensional measurement systems with fringe projection.

In optical shape measurement systems, systematic errors appear as a result of imaging aberrations of the lens assemblies in the cameras and projectors. A mathematical description of this effect is intended to correct the whole measurement area with a few independent coefficients. We apply the ideas of photogrammetry to one- and two-dimensional fringe projection techniques. We also introduce some new terms for close-range applications and telecentric objectives. Further, an algorithm for distance-dependent corrections is introduced. Also, we describe a new method with which to determine coefficients of aberration with an optimization-based method.

Journal Article↗

PubMed2006

Kinematical analysis of the snatch in elite male junior weightlifters of different weight categories.

The purpose of this study was to analyze the differences in the technical pattern of the snatch in elite junior weightlifters of different weight categories. The sample was a group of 33 men weightlifters from different weight categories. The comparative study included 2 groups, taking into account weight categories. Group A included 17 weightlifters from the lightest categories, 56 and 62 kg; group B included 16 weightlifters from the heaviest categories, 85 and 105 kg. Three-dimensional photogrammetry technique was utilized. Regarding group differences, we can conclude that lifters belonging to heavier categories are more efficient, as they manage to have longer barbell propulsion trajectories, which allows them to exert actions on the barbell for a longer period, especially in the initial lifting phase. They attain greater barbell vertical velocity (p = 0.029), a longer vertical bar trajectory normalized on first pull (p = 0.011), and a greater, although limited, bar height loss on the catch (p = 0.008). Besides, intergroup differences evidence that heavier category lifters observe a different temporal organization of the movement based on a longer first pull (p = 0.000), a shorter transition (p = 0.030), and a longer turnover (p = 0.049). No significant differences were found in the analyzed angular parameters during the first and second pull. We believe the intergroup differences found not to be determining enough to consider a technical model adapted to the characteristics of each body weight category. This confirms that a successful lift is multifactor based and individual dependent. Given its transcendence, this evidence should be taken into account in the technical training of young lifters.

Adolescent↗

PubMed2000

In vivo kinematic comparison of posterior cruciate ligament retention or sacrifice with a mobile bearing total knee arthroplasty.

Video fluoroscopy and computer photogrammetry was used to evaluate 20 knees with posterior cruciate ligament (PCL) retaining and 19 knees with PCL sacrificing total knee arthroplasties (TKAs) with a mobile bearing total condylar prosthesis compared with 10 normal patients. In extension, femorotibial contact was posterior for TKA patients (P<.05) and demonstrated anterior translation from 60 degrees-90 degrees flexion. However, posterior rollback with limited translation was seen from 0 degrees-40 degrees, which may reflect the high congruity of this prosthesis. Fifty percent of meniscal bearing implants demonstrated bearing translation. Kinematics and weight-bearing range of motion were similar with PCL retention or sacrifice.

Aged↗

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↗

PubMed2005

VIRTOPSY--scientific documentation, reconstruction and animation in forensic: individual and real 3D data based geo-metric approach including optical body/object surface and radiological CT/MRI scanning.

Until today, most of the documentation of forensic relevant medical findings is limited to traditional 2D photography, 2D conventional radiographs, sketches and verbal description. There are still some limitations of the classic documentation in forensic science especially if a 3D documentation is necessary. The goal of this paper is to demonstrate new 3D real data based geo-metric technology approaches. This paper present approaches to a 3D geo-metric documentation of injuries on the body surface and internal injuries in the living and deceased cases. Using modern imaging methods such as photogrammetry, optical surface and radiological CT/MRI scanning in combination it could be demonstrated that a real, full 3D data based individual documentation of the body surface and internal structures is possible in a non-invasive and non-destructive manner. Using the data merging/fusing and animation possibilities, it is possible to answer reconstructive questions of the dynamic development of patterned injuries (morphologic imprints) and to evaluate the possibility, that they are matchable or linkable to suspected injury-causing instruments. For the first time, to our knowledge, the method of optical and radiological 3D scanning was used to document the forensic relevant injuries of human body in combination with vehicle damages. By this complementary documentation approach, individual forensic real data based analysis and animation were possible linking body injuries to vehicle deformations or damages. These data allow conclusions to be drawn for automobile accident research, optimization of vehicle safety (pedestrian and passenger) and for further development of crash dummies. Real 3D data based documentation opens a new horizon for scientific reconstruction and animation by bringing added value and a real quality improvement in forensic science.

Accidents, Traffic↗

PubMed2005

[Analysis of gait and movement of upper limbs in muscular dystrophies].

INTRODUCTION: The objective is to analyze gait and upper extremity movement in a sample of healthy individuals and patients with different muscular dystrophies and to determine the relationship of the obtained variables with the pattern of muscular involvement. SUBJECTS AND METHODS: Gait and upper limb movement was analyzed with a three-dimensional photogrammetry system. Convenience sample of 28 healthy volunteers, 40 patients with myotonic dystrophy (MD), 9 patients with facioscapulohumeral dystrophy (FSHD) and 14 patients with limb-girdle muscular dystrophy type 2A (LGMD2A). Spatio-temporal and kinematic variables were analyzed. RESULTS: Patients had lower velocity, cadence and shorter stride duration than healthy subjects. Gait and upper extremity kinematic variables suggested proximal muscular involvement in LGMD2A patients and distal muscular abnormalities in MD patients. The most characteristic finding in FSHD patients was related with dorsiflexor muscles' weakness. Some of the variables were also correlated to the patients' functional stage. CONCLUSIONS: This analysis allows the distinction of kinematic and spatio-temporal patterns of gait and upper extremity movement that correlate with muscular dystrophy's phenotype. The use of this analysis in the clinical setting to assess disease progression or the potential effects of treatments requires further studies.

Adult↗

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↗

PubMed1989

[Dynamic study of the optic papilla].

There are several methods of accurately measuring the contours of the papilla and rim. Of these methods, photogrammetry and its refinements are known to provide reproducible results. Unfortunately, there is a discrepancy between the accuracy of these methods and the biological "background noise". This noise does not allow the precision of these methods to be improved beyond a certain level. This also applies for determination of the color of the papilla. An alternative to this problem is to use the "provocation" test. In this article, we try to show the importance of the dynamic test of the papilla (dynamic provoked circulatory response): measuring the change in pallor of the rim during an artificial increase in the intraocular pressure.

Glaucoma↗

PubMed1989

New methods for quantitative and qualitative facial studies: an overview.

The clinical study of birth defects has traditionally followed the Gestalt approach, with a trend, in recent years, toward more objective delineation. Data collection, however, has been largely restricted to measurements from X-rays and anthropometry. In other fields, new techniques are being applied that capitalize on the use of modern computer technology. One such technique is that of remote sensing, of which photogrammetry is a branch. Cartographers, surveyors and engineers, using specially designed cameras, have applied geometrical techniques to locate points on an object precisely. These techniques, in their long-range application, have become part of our industrial technology and have assumed great importance with the development of satellite-borne surveillance systems. The close-range application of similar techniques has the potential for extremely accurate clinical measurement. We are currently evaluating the application of remote sensing to facial measurement using three conventional 35 mm still cameras. The subject is photographed in front of a carefully measured grid, and digitization is then carried out on 35-mm slides specific landmarks on the cranioface are identified, along with points on the background grid and the four corners of the slide frame, and are registered as xy coordinates by a digitizer. These coordinates are then converted into precise locations in object space. The technique is capable of producing measurements to within 1/100th of an inch. We suggest that remote sensing methods such as this may well be of great value in the study of congenital malformations.

Cephalometry↗

PubMed1989

Facial morphology as determined by anthropometry: keeping it simple.

Anthropometry remains an efficient, noninvasive method for describing craniofacial morphology in spite of the appearance of more sophisticated technologies. The major advantage afforded by anthropometry is its technical simplicity, a fact which makes it a readily available tool for evaluating patients, planning facial surgery, or delineating basic features of craniofacial syndromes. Anthropometry lacks the detail of more powerful technologies, but it is better suited for populational studies because of the availability of comparative, normal databases. The standard z-scores produced by such comparisons lend themselves to multivariate analysis. This type of comparative analysis is not yet possible for computerized tomography, three-dimensional imaging, or photogrammetry. To illustrate the utility of this technique an example is cited from an ongoing study of hypohidrotic ectodermal dysplasia (HED) in which anthropometry reveals details of facial morphology overlooked in previous studies. These include the presence of reduced facial height and a striking reduction in the size of the facial features in spite of the fact that facial widths are comparatively normal. Gene carriers show a similar though nonidentical pattern of defects. Like all morphometric approaches, anthropometry has its limitations. Well-designed protocols minimize these limitations by incorporating multiple facial dimensions in the analysis and by emphasizing careful collection of data with standard instruments and methodology.

Cephalometry↗

PubMed1988

Aqueous humor flow measured with fluorophotometry in timolol-treated primates.

Anterior chamber aqueous humor flow rate was measured in unanesthetized owl monkeys using fluorophotometry and anterior chamber photogrammetry. The mean anterior chamber turnover constant (ko) was 0.01, the mean aqueous humor flow rate was 2.75 microliters min-1, and the mean anterior chamber volume was 317 microliters in 16 eyes of eight monkeys. A significantly lower (11%, P less than 0.002) flow rate was measured in the afternoon compared to flow rates measured in the morning. This diurnal cycle is analogous to the fluctuations in flow in humans and supports the hypothesis that aqueous humor formation in primates is regulated by endogenous mechanisms. To investigate the role of adrenergic mechanisms in regulating flow, the dose-response effect of topical timolol (0.5-100 micrograms) was measured. Five microliters drops were used to minimize systemic absorption. Lower concentrations (0.01% and 0.05%) caused sporadic changes in flow. Topical 0.1% timolol (5 micrograms) significantly decreased aqueous humor flow in the treated eye compared to baseline flow while flow in the contralateral eye was not significantly different from baseline flow. Higher concentrations of timolol (0.5% and 1%) caused a dose-related bilateral decrease in flow. These results indicate that even with small topical volumes systemic absorption of the higher concentrations of timolol occurs. Significant local inhibition of flow occurred following 5 micrograms of topical timolol whereas an equal bilateral decrease in flow occurred following a 100 microgram dose. These results suggest that the standard clinical dose (approximately equal to 100 micrograms) is supramaximal for decreasing aqueous flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗