Flying Spot Scanner Research Articles

Molecular imaging and validation of margins in surgically excised nonmelanoma skin cancer specimens.

In an effort to increase the efficiency and cure rate of nonmelanoma skin cancer (NMSC) excisions, we have developed a point-of-care method of imaging and evaluation of skin cancer margins. We evaluate the skin surgical specimens using a smart, near-infrared probe (6qcNIR) that fluoresces in the presence of cathepsin proteases overexpressed in NMSC. Imaging is done with an inverted, flying-spot fluorescence scanner that reduces scatter, giving a 70% improved step response as compared to a conventional imaging system. We develop a scheme for careful comparison of fluorescent signals to histological annotation, which involves image segmentation, fiducial-based registration, and nonrigid free-form deformation on fluorescence images, corresponding color images, "bread-loafed" tissue images, hematoxylin and eosin (H&E)-stained slides, and pathological annotations. From epidermal landmarks, spatial accuracy in the bulk of the sample is , which when extrapolated with a linear stretch model, suggests an error at the margin of , within clinical reporting standards. Cancer annotations on H&E slides are transformed and superimposed on the fluorescence images to generate the final results. Using this methodology, fluorescence cancer signals are generally found to correspond spatially with histological annotations. This method will allow us to accurately analyze molecular probes for imaging skin cancer margins.

On the system stability and calibration of the image plate/scanner system for plasma diagnosis at the National Ignition Facility.

At the National Ignition Facility (NIF), storage phosphor image plates (IP) are used extensively for recording x-rays, charged particles, and neutrons. For x-ray imaging and spectroscopy, absolute and relative calibrations are important for extracting plasma information from the diagnostics. We use Fuji MS, SR, and TR image plates that have been cut to fit custom diagnostic envelopes. The image plates are scanned on a General Electric FLA 7000 IP flying spot scanner. Calibrations for sensitivity, spatial scale, and temperature dependent fade are applied. During a set of recent calibrations, we noticed large shifts in the absolute calibration of the image plate system. The possible source of these shifts is discussed. We discuss scanner stability and a method for calibration. We discuss the fade and temperature effects of the image plates and how this correction is applied within the NIF environment. We also compare our NIF GE FLA 7000 IP scanner with a new General Electric Amersham Typhoon IP scanner.

Stimulated emission depletion microscopy with a supercontinuum source and fluorescence lifetime imaging

We demonstrate stimulated emission depletion (STED) microscopy implemented in a laser scanning confocal microscope using excitation light derived from supercontinuum generation in a microstructured optical fiber. Images with resolution improvement beyond the far-field diffraction limit in both the lateral and axial directions were acquired by scanning overlapped excitation and depletion beams in two dimensions using the flying spot scanner of a commercially available laser scanning confocal microscope. The spatial properties of the depletion beam were controlled holographically using a programmable spatial light modulator, which can rapidly change between different STED imaging modes and also compensate for aberrations in the optical path. STED fluorescence lifetime imaging microscopy is demonstrated through the use of time-correlated single photon counting.

Nephrotoxicity of Bence-Jones proteins: interference in renal epithelial cell acidification.

The aim of the present study was to evaluate the acidification of the endosome-lysosome system of renal epithelial cells after endocytosis of two human immunoglobulin lambda light chains (Bence-Jones proteins, BJP) obtained from patients with multiple myeloma. Renal epithelial cell handling of two BJP (neutral and acidic BJP) was evaluated by rhodamine fluorescence. Renal cells (MDCK) were maintained in culture and, when confluent, were incubated with rhodamine-labeled BJP for different periods of time. Photos were obtained with a fluorescence microscope (Axiolab-Zeiss). Labeling density was determined on slides with a densitometer (Shimadzu Dual-Wavelength Flying-Spot Scanner CS9000). Endocytosis of neutral and acidic BJP was correlated with acidic intracellular compartment distribution using acridine orange labeling. We compared the pattern of distribution after incubation of native neutral and acidic BJP and after complete deglycosylation of BJP by periodate oxidation. The subsequent alteration of pI converted neutral BJP to acidic BJP. There was a significant accumulation of neutral BJP in endocytic structures, reduced lysosomal acidification, and a diffuse pattern of acidification. This pattern was reversed after total deglycosylation and subsequent alteration of the pI to an acidic BJP. We conclude that the physicochemical characteristics of BJP interfere with intracellular acidification, possibly explaining the strong nephrotoxicity of neutral BJP. Lysosomal acidification is fundamental for adequate protein processing and catabolism.

TLC of some free amino acids from sanguine plasma.

This research presents the results obtained from analysis by thin layer chromatography (TLC) of some free amino acids from sanguine plasma samples in the different degree progress in maladies: diabetes, renal syndrome and hepatic cirrhosis. The chromatograms were evaluated with a Shimadzu CS-9000 dual-wavelength flying-spot scanner. Better results were obtained in the case of hepatic cirrhosis.

Fast and noninvasive fluorescence imaging of biological tissues in vivo using a flying-spot scanner.

We have developed a flying-spot scanner (FSS), for fluorescence imaging of tissues in vivo. The FSS is based on the principles of single-pixel illumination and detection via a raster scanning technique. The principal components of the scanner are a laser light source, a pair of horizontal and vertical scanning mirrors to deflect the laser light in these respective directions on the tissue surface, and a photo multiplier tube (PMT) detector. This paper characterizes the performance of the FSS for fluorescence imaging of tissues in vivo. First, a signal-to-noise ratio (SNR) analysis is presented. This is followed by characterization of the experimental SNR, linearity and spatial resolution of the FSS. Finally, the feasibility of tissue fluorescence imaging is demonstrated using an animal model. In summary, the performance of the FSS is comparable to that of fluorescence-imaging systems based on multipixel illumination and detection. The primary advantage of the FSS is the order-of-magnitude reduction in the cost of the light source and detector. However, the primary disadvantage of the FSS its significantly slower frame rate (1 Hz). In applications where high frame rates are not critical, the FSS will represent a low-cost alternative to multichannel fluorescence imaging-systems.

Automated multiple development thin layer chromatography of some plant extracts

The separation of ten plant extracts using automated multiple development thin-layer chromatography (AMD-TLC) is described. Alcoholic extracts were obtained from Cinchona succirubra, Aesculus hippocastanum, Berberis vulgaris, Artemisia abrotanum, Carduus marianus, Thuja occidentalis, Baptisia tinctoria, Paulinia cupana, Lycopus europaeus and Echinacea angustifolia. The separation was performed on silica plates (Sil G-50 UV 254 (Macherey—Nagel), 10 × 20 cm). AMD was achieved in 25 steps using methanol, ethyl acetate, toluene, 1,2-dichloroethane, 25% ammonia solution and anhydrous formic acid as modifiers. The chromatograms were evaluated with a Shimadzu CS-9000 dual-wavelength flying-spot scanner. Better separations were obtained using AMD than isocratic elution.

Texture analysis of histological images of giant cell tumor of bone

To gain an objective evaluation of histological sections of giant cell tumors of bone (GCT) and osteosarcomas, microscopic pictures were taken and their grey-tone image measured, using a flying spot scanner and computer. Various values of eight parameters expressing certain characteristical brightness distribution patterns were computed, and comparatively examined among the three groups of benign GCT, malignant GCT and osteosarcoma. As a result, some parameters could facilitate differentiation between the histological images of these bone tumors. Especially, "angular second moment (ASM)", "Contrast" and "Coefficient of variation (COV)" were useful even for discrimination between malignant and benign GCT. After factor analysis of the values of these parameters, scores of each factor for a number of histological scene images were plotted on a 2-dimensional factor plane. On this plane, which was considered to be a histological feature plane, cases of benign GCT were separated from those of osteosarcoma. Cases of malignant GCT were distributed between the two groups. These results suggest that this method could be valuable for computer evaluation of histological images of benign GCT and osteosarcomas.

Fluorometric analysis of uranium(VI) by means of extraction and flying spot scanner

A fluorometric method for the determination of ng amounts of uranium has been developed. Instead of using the conventional solid fluorescent photometry with pellets, the uranium fluorescence in a spot of the trioctylphosphine oxide-benzene extract on a TLC plate is continuously monitored by means of a flying spot scanner. The proposed method may be usefully applied to small amounts of inorganic and biological samples, because it excludes the pellet preparation and is therefore able to analyze more samples per unit of time than the conventional method. The interferences by coexisting elements as encountered in the conventional method are eliminated by preceding extraction.

A scanning photon microscope for non-destructive observations of crystal defect and interface trap distributions in silicon wafers

A sophisticated flying spot scanner in which 2 kHz AC surface photovoltages induced in a Si wafer due to the chopped irradiation of a photon beam 0.4 mm in diameter are non-destructively measured through a 25 mu m air gap between the wafer surface and a transparent electrode is developed. Photovoltage distributions on a wafer 50 to 150 mm in diameter are measured in 5 min, and displayed as a 512*480 pixel black and white image. With the use of near infrared (peaking at 896 and 1076 nm) and blue (peaking at 448 nm) photon sources (cathode ray tubes), it is possible to measure crystal defect distribution in the bulk and interface trap distribution at the wafer surface separately. The apparatus is successfully applied to observations of swirl patterns and radiation damage induced by an electron beam in thermally oxidised p-type Si wafers.

Double-beam flying spot scanner for two-dimensional polyacrylamide gel electrophoresis

The construction of a double-beam photometer in which the light source is a cathode ray oscilloscope is described. The light spot from the oscilloscope was focused and reduced in size at the gel plane to give a diameter of <0.15 mm and make it possible to scan over a 50 × 59mm rectangle; using reduced spatial resolution (spot <0.2 mm) the area scanned becomes 70 × 90 mm. The light from the CRT was divided into two beams; one was directed through the transparent object to a photomultiplier and the other to a reference photomultiplier. The signals from these two detectors were converted to the logarithm of the ratio by a logging amplifier to give a direct measure of absorbance. Positioning of the spot, control of light intensity, and measurement of absorbance were carried out through an interface to a 16-bit computer. The relationship between measured and actual absorbance was linear over the range of absorbance 0 to 2, which could be raised to 1 to 3 by placing a neutral filter in the reference beam. The system generated an image containing 256 × 256 pixels in about 5 min, the scanning speed was determined by the persistence time of the P4 phosphor on the cathode ray tube, and faster scans can be made using A6 phosphor.

Scophony Spatial Light Modulator

An alternative to the conventional flying-spot scanner architecture is the Scophony scanner. The Scophony scanner uses the same optical elements as the more familiar flying-spot scanner: a rotating polygon mirror, an acousto-optic (A/O) modulator, and a laser light source. The flying-spot scanner is designed to construct its image a pixel at a time; no more than one pixel is illuminated at any given instant. The Scophony scanner is designed to image a broad swath of the A/0 modulator's acoustic pulses onto the photoreceptor. Many pixels are illuminated at any given instant in the Scophony scanner. The result is a scanner with a coherent imaging response. This coherent response implies that the phase of the modulator's electronic drive signal for a given pixel profoundly influences the formation of the neighboring pixels at the scanner image plane. This coherent response enables electronic manipulation of the video drive signal to have significant impact on the optical imaging performance of the scanner. In this paper, two electronic manipulation schemes are pro-posed for doubling the resolution of the Scophony scanner, one scheme for analog video signals and one scheme for binary digital video signals. Each scheme gives superior contrast ratio performance when compared with the flying-spot scanner.

Minority-carrier lifetime mapping in silicon using a microprocessor-controlled flying-spot scanner

An automatic flying-spot scanner with fast data acquisition is described, which is used for the characterisation of semiconductor samples. The measurement system can be used for the visualisation of resistivity and lifetime inhomogeneities across a semiconductor sample, information about surface conditions (mainly surface-recombination velocity) and for the measurement of minority-carrier lifetime in discrete lateral points resulting in lifetime maps of the sample. The technique described utilises the photocurrent collected at a reverse biased rectifying junction at the rear side of the sample. The authors present measurements of lifetime in silicon p+n-junctions. The lifetime distributions are visualised as maps of the absolute lifetime values against position and as computed blackness-modulated maps. The latter type of map provides an easier analysis of the measurement than the former. Necessary surface precautions are also discussed.

Intravenous left ventriculography utilizing digital subtraction technique.

To detect the left ventricular boundary in the intravenous ventriculography, we used a subtraction technique for background suppression. Images containing contrast medium and reference mask images were transferred to a computer through a flying spot scanner and stored on the digital disc. Stored reference mask images were subtracted from the digitized contrast images. The resulting images were then electronically enhanced to extract the left ventricular (LV) image. The LV boundary was delineated with an algorithm we have developed and the volume of the LV cavity was calculated automatically. The validity of this method was compared with data obtained from conventional left ventriculogram (LVG). In 11 patients, values for end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF) calculated from the intravenous LVG were correlated closely with those from the conventional LVG (128 +/- 38 (SD) vs 133 +/- 39 ml, r = 0.95; 50 +/- 28 vs 53 +/- 30 ml, r = 0.98; 63 +/- 10 vs 62 +/- 12%, r = 0.96, respectively). Nine patients with valvular regurgitation were followed up serially after valve replacement. EDV index fell significantly after corrective surgery (145 +/- 50 to 81 +/- 33 ml/m2, p less than 0.02), whereas, EF was affected variably depending upon the preoperative state (58 +/- 13 to 61 +/- 11%, not significant). Thus, this method is less invasive than conventional LVG and has successfully allowed for sequential determination of ventricular function on an outpatient basis.

A μp-controlled flying-spot scanner with an intelligent A/D-converter unit

A flying-spot scanning technique is useful for the measurement and mapping of inhomogeneities in semiconductor parameters such as minority carrier lifetime, resistivity, and surface-recombination velocity. This paper describes a system based on a 16-bit microprocessor and an intelligent 12-bit A/D-acquisition unit for automatic control and data processing of the measurement. The processor controls the scanning equipment while the intelligent A/D unit supervises the measurement by means of a single-chip microcomputer analyzing feedback signals from the scanner. Therefore, real-time data processing is achieved which significantly enhances the applicability of the flying-spot scanning technique.

A 70-mm Film Laser Telecine for High-Definition Television

This paper details a new telecine for use in high-definition television. The telecine incorporates a laser flying spot scanner, and was designed to use 70-mm motion-picture film to obtain better picture quality. An outline of principles is presented, as well as the features, configurations, and characteristics of the new laser telecine.

Interactive Flying Spot Image Scanner For Direct Matching Of Photographic Film Pictures And Digital Images

This paper deals with an interactive flying spot scanner connected to a digital picture processing system. Its structure is discussed. One of the characteristics is analyzed in detail: the possibility of proceeding to interactive geometrical deformations with a programmable scanning system. A type of deformation was selected, and the principle of its implementation is outlined. The procedure which enables the execution of a geometric matching of a topographic map and a Landsat digital image is given as an application example. The main advantages of this method are pointed out.

From picosecond pulses to lens design

The research interests within the Optics Section of Imperial College are diverse, from laser physics, ultrashort light pulses, uv lasers and nonlinear optics to lens design, optical instrumentation, image processing, electron optics, holography and coherent optics. A specific example is the project in which transparencies of LANDSAT pictures in four wavebands are scanned with a flying spot scanner and the resulting video signals are mixed to produce a false colour composite.

Observation of p-n Junctions with a Flying-Spot Scanner Using a Chopped Photon Beam

A flying-spot scanner that employs a chopped photon beam emitted from a cathode ray tube is reported. The photon beam scanns a planar p-n junction put on a metal electrode through a In2O3-coated transparent electrode and a 15 µm-thick mylar spacer. The ac photovoltage is picked up with electrodes through a condensor formed by the spacer. The photovoltage signal modulates brightness of another cathode ray tube to form a scanning image. Mean wavelength and chopping frequency of the photon beam are 507 nm and 2 kHz. Scanning image analysis is done using photocurrent density equations based on a step-like junction model. Three kinds of junctions, a solar cell, a partly-deep junction and a non-uniformly ion implanted one, have been evaluated to show the validity of the present method.

Photography as a technique for studying visual range

A technique is described that uses black and white and color photography to study visual range, and the effects of clouds and haze on a scene. Black and white film is used for quantitative measurement of visual range. Film density measurements are digitized using a flying spot scanner to assure that the measurement, analysis and interpretation are reproducible and accurate. The density wedges and the negatives are digitized. The procedure and an example are presented. Color film is used to qualify the black and white measurements. The techniques applied in analysis and some results of the field measurement program are presented.