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Optical properties of flexible fiber-optic endoscopes, requirements to them and methods of their testing are under consideration in this article. This results of the research performed became the basis for developing a State USSR Standards entitled "Medical endoscopic instruments with fiber optics. General technical requirements."
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A method for the measurement of light transmission is described. It makes use of an illuminator, a photometer to which a measuring and a reference photocell are connected, a bifurcated light guide and four special holders, two for the photocells and two for the branches of the light guide. The reference photocell gives the values of the first intensity while the measuring photocell, covered by the sample to be examined, gives the values of the second intensity. By just switching from one photocell to the other, without moving the sample it is possible to verify the values of both the first and the second intensity and consequently insure more precise measurements.
Three instruments for making in-vivo light transmission measurements are described. They consist of a special holder for the photocell to be connected to the photometer, a fiber optic light guide to be connected to the illuminator, and the instrument itself which holds them together in a way so that the beam of light impinges directly on the photocell. A graded ruler, along with a vernier, make it possible to measure the thickness of the tissue as well.
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1. The changes introduced in a photographic camera in order to obtain endoscopic pictures in a 35 mm format and consequently increasing the size of the image up to 22 mm are described. 2. The details of the photographic technique used are listed. 3. This technique is presented for comparison with the conventional technique.
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BACKGROUND: The transient but substantial alterations in the biliary system during pregnancy increase the risk of cholecystitis, choledocholithiasis, and pancreatitis. Traditionally, these disorders are managed conservatively or with operative cholecystectomy. Recent advances in fiber-optic technology allow endoscopy to be used as a safe, effective, and definitive treatment alternative for pancreaticobiliary disease in pregnancy. CASES: Three gravid women with cholelithiasis, acute cholecystitis, and/or gallstone pancreatitis were treated endoscopically with stone extraction and experienced rapid resolution of symptoms and successful pregnancy outcomes. CONCLUSION: Aggressive endoscopic intervention for biliary disorders in pregnancy appears to decrease morbidity, mortality, and costs. Endoscopy offers a safer, more effective treatment alternative to prolonged medical management and traditional surgical intervention during pregnancy. Because biliary abnormalities resolve rapidly in the postpartum period, it is unlikely these women will need subsequent treatment.
Optical coherence tomography (OCT) is a novel technique for two and three-dimensional imaging of tissues at a histological level. The technique is based on optical technology and commercially available fiber-optic components that may be adapted for use in conventional endoscopes or intravascular catheters. OCT is a non-invasive technique, which does not utilize ionizing radiation, and it may within a few seconds provide in vivo images ("optical biopsies") of tissues in cases where excisional biopsy is hazardous or impossible, or when repeated examinations are required. OCT has numerous potential clinical applications, and the technique is currently used in ophthalmology, where it may improve diagnosis and therapeutic control of various eye diseases. Detection and characterization of skin tumors and other dermatological diseases is another area where OCT has tremendous clinical potential. In the field of cardiology, intravascular OCT may be capable to contribute to early diagnosis of vulnerable atherosclerotic lesions. The OCT technique is also being developed in other clinical areas and is expected to become integrated in a range of clinical situations in the future.
We demonstrate the feasibility of using Drop-on-Demand microjet printing technology for fabricating imaging sensors by reproducibly printing an array of photo-polymerizable sensing elements, containing a pH sensitive indicator, on the surface of an optical fiber image guide. The reproducibility of the microjet printing process is excellent for microdot (i.e. micrometer-sized polymer) sensor diameter (92.2+/-2.2 microm), height (35.0+/-1.0 microm), and roundness (0.00072+/-0.00023). pH sensors were evaluated in terms of pH sensing ability (< or =2% sensor variation), response time, and hysteresis using a custom fluorescence imaging system. In addition, the microjet technique has distinct advantages over other fabrication methods, which are discussed in detail.
Fifty-five patients with symptomatic bladder outlet obstruction were treated with laser ablation of the prostate using right-angle fibers to deliver Nd:YAG laser energy. Dosimetry ranged between 60 and 80 W power in a noncontact mode to achieve both coagulation and vaporization of adenomatous prostate tissue. Most patients were followed for > 1 year. Efficacy of treatment was assessed with American Urological Association (AUA) symptom scores, uroflow studies, need for revision procedures, and catheterization. Perioperative morbidity and complications demonstrate results comparable to published statistics for transurethral resection of the prostate (TURP). Because patients with glands larger than 40 cm3 showed more postoperative symptoms of irritation and obstruction, 18 patients had visual laser ablation of the prostate (VLAP) alone and 37 patients were treated with a limited TURP, or TURPETTE, which includes removal of the coagulated tissue immediately after lasing to facilitate earlier voiding with minimal bleeding. The evolution of this combined technique in those patients with larger glands encourages more rapid urinary flow by providing an immediate channel, reducing acute swelling, and shortening the duration of necrotic slough. Eighty-six percent of patients voided with improved flow and reduced AUA symptom score. Fourteen percent required a revision procedure due to obstruction or bleeding. Modification in surgical technique and improved optical characteristics of fiber technology will determine the future of laser application to prostate surgery.
Fiber optic probes are a key element for biomedical spectroscopic sensing. We review the use of fiber optic probes for optical spectroscopy, focusing on applications in turbid media, such as tissue. The design of probes for reflectance, polarized reflectance, fluorescence, and Raman spectroscopy is illustrated. We cover universal design principles as well as technologies for beam deflecting and reshaping.
A magneto-optical data storage system utilizing single-mode fiber is capable of providing high signal-to-noise ratio (SNR) recording if laser noise sources are properly managed. In particular, mode partition noise (MPN) associated with use of a Fabry-Perot laser diode can be a significant problem in a fiber-based system. The various mechanisms leading to MPN as well as to laser phase noise are discussed in the context of a system constructed with polarization-maintaining fiber. The primary noise mechanisms include spurious fiber-endface reflections and errors in the quarter-wave plate on the recording head. An understanding of these effects is essential for fabrication of a fiber-based recording system with suitable SNR performance.
Biosensor technology has a great potential to meet the need for sensitive and nearly real-time microbial detection from foods. An antibody-based fiber-optic biosensor to detect low levels of Listeria monocytogenes cells following an enrichment step was developed. The principle of the sensor is a sandwich immunoassay where a rabbit polyclonal antibody was first immobilized on polystyrene fiber waveguides through a biotin-streptavidin reaction to capture Listeria cells on the fiber. Capture of cells on the fibers was confirmed by scanning electron microscopy. A cyanine 5-labeled murine monoclonal antibody, C11E9, was used to generate a specific fluorescent signal, which was acquired by launching a 635-nm laser light from an Analyte 2000 and collected by a photodetector at 670 to 710 nm. This immunosensor was specific for L. monocytogenes and showed a significantly higher signal strength than for other Listeria species or other microorganisms, including Escherichia coli, Enterococcus faecalis, Salmonella enterica, Lactobacillus plantarum, Carnobacterium gallinarum, Hafnia alvei, Corynebacterium glutamicum, Enterobacter aerogenes, Pseudomonas aeruginosa, and Serratia marcescens, in pure or in mixed-culture setup. Fiber-optic results could be obtained within 2.5 h of sampling. The sensitivity threshold was about 4.3 x 10(3) CFU/ml for a pure culture of L. monocytogenes grown at 37 degrees C. When L. monocytogenes was mixed with lactic acid bacteria or grown at 10 degrees C with 3.5% NaCl, the detection threshold was 4.1 x 10(4) or 2.8 x 10(7) CFU/ml, respectively. In less than 24 h, this method could detect L. monocytogenes in hot dog or bologna naturally contaminated or artificially inoculated with 10 to 1,000 CFU/g after enrichment in buffered Listeria enrichment broth.