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At least 1,099 records · Page 61Linked to original sources
PubMed1999

Interactive images in the operating room.

Fluoroscopy has made endourology possible, but its two dimensionality and poor tissue contrast limit its applications. Recent advances in computer technology are making it possible for surgeons to interact with three-dimensional CT and MR images. Initial interactive navigation systems tracked the position of surgical instruments on previously acquired images using optical, ultrasonic, or electromagnetic devices. More recently, real-time imaging and instrument tracking have become possible, such as with the open interventional MR scanners. The problems created by patient motion and tissue deformation during manipulation may thereby be overcome.

Diagnostic Imaging↗
PubMed2001

The development of the Ocutech VES-autofocus telescope and a future binocular version.

Conventional optical low-vision devices are hampered by the physical constraints of magnification-shallow depth of field and narrow field of view, and for telescopes, the need to change focus for different distances. These characteristics make low-vision telescopic aids difficult to use, especially at important midrange distances. The Ocutech VES Autofocus bioptic telescope (VES-AF) funded with National Institutes of Health-Small Business Innovation Research and Ontario (Canada) Ministry of Health grants, eliminates the need to manipulate the device to maintain focus. Clinical experience with the VES-AF has shown that autofocus (AF) enhances the acceptance and utilization of telescopic devices. Difficulty ignoring the fellow eye while sighting through the device has been a complaint of users that has undermined device acceptance. Although occlusion is an option to alleviate the diplopia experienced, the development of a binocular version may further enhance the acceptance, adaptation to, and utilization of telescopic devices and may offer wider fields of view as well.

Adult↗
PubMed2000

Rectus abdominis muscle free flap harvest by laparoscopic sheath-sparing technique.

Previous reports of endoscopic rectus abdominis muscle harvest have described techniques that are hampered by the need for anterior rectus sheath division or mechanical devices to maintain the optical cavity. The authors report the first successful clinical case of a laparoscopic sheath-sparing rectus abdominis muscle harvest for free tissue transfer. It offers considerable advantages over the traditional open method and, with the help of an experienced laparoscopic surgeon, it should add little to operative time.

Aged↗
PubMed2006

Structure of phase change materials for data storage.

Phase change materials based on chalcogenide alloys play an important role in optical and electrical memory devices. Both applications rely on the reversible phase transition of these alloys between amorphous and metastable cubic states. However, their atomic arrangements are not yet clear, which results in the unknown phase change mechanism of the utilization. Here using ab initio calculations we have determined the atomic arrangements. The results show that the metastable structure consists of special repeated units possessing rocksalt symmetry, whereas the so-called vacancy positions are highly ordered and layered and just result from the cubic symmetry. Finally, the fast and reversible phase change comes from the intrinsic similarity in the structures of the amorphous and metastable states.

Journal Article↗
PubMed1998

Design of an 18 m spherical-grating monochromator at UVSOR.

An 18 m spherical-grating monochromator with high resolution and high photon flux has been developed at the bending-magnet beamline BL2B2 of the UVSOR facility in the Institute for Molecular Science. The monochromator is designed to cover the energy range 20-200 eV by using three gratings: G1 (2400 lines mm(-1), R = 18 m) at 80-200 eV; G2 (1200 lines mm(-1), R = 18 m) at 40-100 eV; G3 (2400 lines mm(-1), R = 9.25 m) at 20-50 eV. A resolving power of 5000 and a photon flux of more than 10(10) photons s(-1) are expected at a 100 mA ring current. A small including angle of 140 degrees is adopted for G3 and two plane mirrors coated with aluminium are located between G3 and the exit slit as optical filters. These geometrical devices may contribute significantly to the reduction of the high-order lights.

Journal Article↗
PubMed1993

Compressing data volume of left ventricular cineangiograms.

In this paper a method of compressing data volume for left ventricular cineangiograms is proposed. This method enables digital-optical discs to store the cineangiograms with an equivalent recording density to that of HDTV VTR's while preserving the quality of the original image. The data volume of the cineangiograms is compressed by approximating function and storing its coefficients. With this method, each cineangiogram frame is first decomposed into three regions: the inner part, the inner wall, and the background (using a statistical method previously reported by the authors). Each region is then compressed by means of a difference operation and an adaptive approximation with smooth functions. Performance is tested on 20 cases using actual cineangiograms. The specifications were verified for a spatial resolution of 1000 TV lines, a dynamic range of 60 dB, an SNR of 40 dB [pp/rms], volume compression to 7% of the original volume, and 0.19 [second/frame] for decoding on a 1.7 MFLOPS computer.

Algorithms↗
PubMed2005

Interferometric detection in picosecond ultrasonics for nondestructive testing of submicrometric opaque multilayered samples: TiN/AlCu/TiN/Ti/Si.

An experimental investigation of nanometric thin films by a picosecond ultrasonic technique is presented. A photoelastic model is used with an interferometric device, combined with ultrafast optical pump and probe setup, to measure the thicknesses of submicrometric layers made of TiN, Ti, and AlCu deposited on silicon (Si) wafers. The results are in good agreement with ellipsometry measurements showing that the picosecond ultrasonic technique can give accurate results even when the reflectance signal is very low. Additional important results are first, that the adhesion of the TiN surface film is probed by processing both the frequency and the damping of the oscillation of a resonance acoustic mode; and second, the presence of a thin buried TiN layer under an opaque AlCu film is highlighted by the interferometric setup.

Journal Article↗
PubMed1990

Clear ultraviolet blocking lenses for use by PUVA patients.

It is well recognized that patients receiving photochemotherapy (PUVA) need to wear UV-blocking sunglasses on the day of ingestion of 8-methoxypsoralen. For many patients the wearing of tinted sun-glasses causes difficulties because they interfere with colour perception, reduce definition in conditions of low background light and often because they are considered 'cosmetically unacceptable'. In this study the UV-blocking properties of a number of lenses with little or no tint were assessed. The following lenses or lens coatings were found to be suitable for use by PUVA patients: Orcolite UV 400, Orma UVX, Rodenstock Lambda 400, Sola UV Gard 400 and Polaroid polarizing lenses.

Cataract↗
PubMed2006

Facial templates: a new perspective in three dimensions.

PURPOSE: This paper describes the use of adult facial template in gender-specific facial analysis. SUBJECTS AND METHODS: Eighty adults, mean age 24.5, were selected for the study. Laser-scanned images of the subjects were obtained under a reproducible and controlled environment with two Minolta Vivid 900 (Osaka, Japan) optical laser-scanning devices assembled as a stereo-pair. A set of left and right scanned images was taken for each subject and each scan took an average of 2.5 s. These scanned images were processed and merged to form a composite three-dimensional soft tissue reproduction of the subjects using commercially available reverse modelling software. The differences in facial morphology were measured using shell deviation colour maps. The facial template was used to compare differences between males vs. females groups and two subjects with facial disproportions. RESULTS: The difference between the male and female facial templates was 1.28 +/- 1.02 mm. The areas of greatest deviation were at the nasal, zygomatic area and lower jaw line. The results of the surface deviation maps between the templates and subjects with facial disproportion showed that the results could be applied for orthodontic diagnosis. CONCLUSIONS: The construction of the adult facial templates provides an interesting perspective into measuring changes in groups of patients and also acts as a useful template for the comparison of skeletal disproportion.

Adult↗
PubMed1998

Physiological and pathological factors of human breast disease that can influence optical diagnosis.

The 'normal' human female breast is a very complex organ that changes considerably during development, pregnancy and menopause. In addition, it is an excretory organ that, during lactation, discharges various metabolites and certain drugs that can be optically active. Optical diagnosis of breast cancers requires detection of differential concentrations of 1) various absorbers and scatterers or 2) native or exogenous fluorophores to distinguish cancers from surrounding 'normal' and benign breast tissues. The differential concentrations are due to the biology of the cancer cells and the host responses to the cancer growth. For most patients, the cancer will be intermixed with a complex 3-dimensional array of 'normal' breast tissue and benign breast lesions. This complexity will challenge the optical biopsy investigator but, with the recent advances in our understanding of light transport, optical diagnostic techniques and devices can be developed to complement and supplement current breast cancer screening techniques.

Breast↗
PubMed2003

Structural changes in loaded equine tendons can be monitored by a novel spectroscopic technique.

This study aimed to investigate the preferential collagen fibril alignment in unloaded and loaded tendons using elastic scattering spectroscopy. The device consisted of an optical probe, a pulsed light source (320-860 nm), a spectrometer and a PC. Two probes with either 2.75 mm or 300 microm source-detector separations were used to monitor deep and superficial layers, respectively. Equine superficial digital flexor tendons were subjected to ex vivo progressive tensional loading. Seven times more backscattered light was detected parallel rather than perpendicular to the tendon axis with the 2.75 mm separation probe in unloaded tendons. In contrast, using the 300 microm separation probe the plane of maximum backscatter (3-fold greater) was perpendicular to the tendon axis. There was no optical anisotropy in the cross-sectional plane of the tendon (i.e. the transversely cut tendon surface), with no structural anisotropy. During mechanical loading (9-14% strain) backscatter anisotropy increased 8.5- to 18.5-fold along the principal strain axis for 2.75 mm probe separation, but almost disappeared in the perpendicular plane (measured using the 300 microm probe separation). Optical (anisotropy) and mechanical (strain) measurements were highly correlated. We conclude that spatial anisotropy of backscattered light can be used for quantitative monitoring of collagen fibril alignment and tissue reorganization during loading, with the potential for minimally invasive real-time structural monitoring of fibrous tissues in normal, pathological or repairing tissues and in tissue engineering.

Animals↗
PubMed2006

Sensitivity of linear CCD array based film scanners used for film dosimetry.

Film dosimetry is commonly performed by using linear CCD array transmission optical densitometers. However, these devices suffer from a variation in response along the detector array. If not properly corrected for, this nonuniformity may lead to significant overestimations of the measured dose as one approaches regions close to the edges of the scanning region. In this note, we present measurements of the spatial response of an AGFA Arcus II document scanner used for radiochromic film dosimetry. Results and methods presented in this work can be generalized to other CCD based transmission scanners used for film dosimetry employing either radiochromic or radiographic films.

Computer Peripherals↗
PubMed1993

Optical imaging systems--the future of medical record storage.

This paper explains the processes which were undertaken to solve the problem of lack of storage for medical records at Logan Hospital. The paper contains analysis of why optical disk proved to be the most appropriate storage medium, and the system components of an Optical Disk System. A detailed description of how the Optical Imaging System has been structured and the processes which make the Optical Disk System a major part of the hospital's Health Information System is provided. The paper also discusses the much talked about legal side of optical imaging. Lastly the paper explains the future plans of Logan Hospital's Medical Record Storage System.

Hospital Bed Capacity, under 100↗
PubMed2002

Hand-held digital video-camera for eye examination and follow-up.

We developed a hand-held digital colour video-camera for eye examination in primary care. The device weighed 550 g. It featured a charge-coupled device (CCD) and corrective optics. Both colour video and digital still images could be taken. The video-camera was connected to a PC with software for database storage, image processing and telecommunication. We studied 88 normal subjects (38 male, 50 female), aged 7-62 years. It was not necessary to use mydriatic eye drops for pupillary dilation. Satisfactory digital images of the whole face and the anterior eye were obtained. The optic disc and the central part of the ocular fundus could also be recorded. Image quality of the face and the anterior eye were excellent; image quality of the optic disc and macula were good enough for tele-ophthalmology. Further studies are needed to evaluate the usefulness of the equipment in different clinical conditions.

Adolescent↗
PubMed2007

Dual-peak long-period fiber gratings with enhanced refractive index sensitivity by finely tailored mode dispersion that uses the light cladding etching technique.

We have experimentally investigated the mode dispersion property and refractive index sensitivity of dual-peak long-period fiber gratings (LPGs) that were sensitized by hydrofluoric acid (HF) etching. The nature of the coupled cladding modes close to the dispersion turning point makes the dual-peak LPGs ultrasensitive to cladding property, permitting a fine tailoring of the mode dispersion and index sensitivity by the light cladding etching method using HF acid of only 1% concentration. As an implementation of an optical biosensor, the etched device was used to detect the concentration of hemoglobin protein in a sugar solution, showing a sensitivity as high as 20 nm/1%.

Journal Article↗