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PubMed2002

The effect of pixel nonlinearity on cathode-ray tube-based visual acuity tests.

BACKGROUND: Pixel nonlinearity of a cathode-ray tube (CRT) display can cause differences between the actual image and the nominal image. One of the discrepancies, the anisotropy of interactions between neighboring pixels on the same raster line and between neighboring raster lines, may have an impact on the CRT-based visual acuity test where small horizontal and vertical gaps are used. We evaluated this impact. METHOD: Two high-quality color CRT monitors were tested. The stimulus target was a black square ring on a white background. White gaps of one stroke width were opened in the middle of the straight sides of the square ring. In a gap width comparison study, the up and down gaps were flanked with a one-pixel band on the left and right side. The pixel value of the bands was varied to determine the luminance that made up and down gaps appear to have the same width as left and right gaps. The comparison was made at 1 and 2 m. In a visual acuity study, horizontal gap (left/right) acuity and vertical gap (up/down) acuity were measured separately at several distances between 8 and 11 m. Similar measurements were made when the monitor was rotated 90 degrees. RESULTS: Gaps with edges that were parallel to raster lines (raster-parallel gaps) appeared wider than gaps with edges that were perpendicular to raster lines (raster-perpendicular gaps). To match the apparent width of the left and right gaps, the two one-pixel bands flanking the up and down gaps required a pixel value that corresponded approximately to a luminance of mid gray, indicating that the apparent width of a four-pixel left or right gap was similar to that of a five-pixel up or down gap. Raster-parallel gaps produced a higher percentage of correct responses than raster-perpendicular gaps in a visual acuity test. When nominal gap widths were equal, left and right gaps produced 10% or more correct responses than up and down gaps at some target sizes, which translated to a two-letter acuity difference. This acuity difference could not be accounted for by uncorrected astigmatism because the anisotropy persisted when the monitor was turned 90 degrees. CONCLUSIONS: Pixel nonlinearity of a CRT-display results in an anisotropy of gap width that can be observed at and above visual acuity size. This anisotropy may introduce uncertainties in the results of CRT-based visual acuity tests where gaps of different orientations are used.

Anisotropy↗
PubMed1999

Detection of caries with conventional digital imaging and tuned aperture computed tomography using CRT monitor and laptop displays.

OBJECTIVE: The purpose of this study was to compare the diagnostic performance of conventional digital images and tuned aperture computed tomography (TACT) slices in caries detection through use of cathode-ray tube monitor and laptop displays. STUDY DESIGN: Forty-two extracted posterior teeth were mounted and imaged with a direct digital radiography system. Conventional digital bitewing projections and TACT slices were acquired. Images were viewed on a high-resolution cathode-ray tube monitor and on an active-matrix laptop display. Eight observers assessed caries status of occlusal and proximal surfaces of the teeth using all combinations of image and display modality. Observers' assessments were compared with the results of histologic examination of tooth sections. Possible differences in receiver operating characteristic curve areas among displays, image modalities, observers, and surfaces were analyzed by means of analysis of variance. RESULTS: There was no statistically significant difference between the diagnostic performances provided by the cathode-ray tube monitor and laptop displays in caries detection (P = .588). In addition, the performances of digital images and TACT slices were not significantly different (P = .843). CONCLUSIONS: Modern active-matrix laptop displays provide diagnostic quality for caries detection comparable to that obtainable with cathode-ray tube monitors.

Analysis of Variance↗
PubMed2002

Influence of room lighting on grey-scale perception with a CRT-and a TFT monitor display.

OBJECTIVES: To determine the influence of ambient lighting on grey-scale perception using a cathode-ray tube (CRT) and a thin film transistor (TFT) computer display. METHODS: A cathode ray tube (Nokia XS 446) and a liquid crystal display (Panasonic LC 50S) were used at reduced room lighting (70 lux) and under conditions recommended for a dental operatory (1000 lux). Twenty-seven observers examined twice a modified SMPTE test pattern [0 to 255; 255 to 0] grey-scale values. The corresponding contrast differences were allocated to four ranges of grey levels (I: 0-63; II: 64-127; III: 128-191; IV: 192-255). The influences of monitor type, grey-scale range and illumination were evaluated by means of repeated measures analysis of variance. RESULTS: Detection of differences in monochromatic intensity was significantly earlier with reduced lighting (P<0.0001). When full ambient lighting was used, the TFT display was superior compared to the CRT monitor in ranges II and III (P<0.0001), whereas no differences could be detected for grey intensities between 0 and 63 (P=0.71) and between 192 and 255 (P=0.36). CONCLUSIONS: Background lighting hampers grey-scale perception on computer displays. In this study of one TFT and one CRT monitor, the TFT in full ambient lighting was associated with earlier detection of grey scale differences than CRT.

Adult↗
PubMed2006

Endoscopic transsphenoidal pituitary surgery with intraoperative magnetic resonance imaging.

OBJECTIVE: The two most recent significant advances in pituitary surgery have been the endonasal endoscopic approach and intraoperative magnetic resonance imaging (IMRI). Each provides improved visualization of intra- and parasellar anatomy with the goal of attaining a complete resection. The combination of the two techniques has not been previously reported in the literature. METHODS: We performed endoscopic, endonasal resection of pituitary macroadenomas in 15 patients using the Polestar N-10 (0.12T) IMRI (Odin Medical Technologies, Inc., Newton, MA). Eleven patients had nonfunctioning tumors, three had acromegaly, and one had a medication-resistant prolactinoma. The effect of the magnetic field on the cathode ray tube screen and the image quality of the IMRI images were assessed. The presence of residual tumor on IMRI was noted and then re-examined with the endoscope. RESULTS: Although the Polestar N-10 is a low Tesla magnet, the IMRI caused significant distortion of the cathode ray tube screen regardless of the viewing angle. This was overcome with the use of a wall-mounted plasma screen. IMRI images were obtained in all cases and were of sufficiently high quality to demonstrate adequate decompression of the optic chiasm and the removal of all suprasellar tumor. In three cases, residual tumor was found with IMRI that was resected endoscopically before the completion of surgery. In four other cases, potential residual tumor was examined endoscopically and found to be normal postoperative change. In eight cases no residual intrasellar tumor was seen on the IMRI. Preresection visual deficits improved in all cases and the insulin-like growth factor levels normalized in two of three cases. There were no delayed cerebrospinal fluid leaks. CONCLUSION: Combining intraoperative endoscopy and IMRI is feasible and distortion of the cathode ray tube screen can be overcome with the use of either a plasma or liquid crystal display screen. Each technology provides complementary information, which can assist the surgeon in safely maximizing the extent of resection. In this small series using a low-field magnet, rates of residual tumor following endoscopic transsphenoidal surgery were less than have been reported following microscope-based transsphenoidal surgery.

Adenoma↗
PubMed2002

Modeling the bidirectional reflectance of emissive displays.

The reflection properties of a display device influence the available contrast and affect the perception of subtle detail. The display reflection characteristics of flat-panel displays (FPDs) are appropriately described by a six-dimensional bidirectional reflectance distribution function (BRDF). I describe a Monte Carlo method for modeling the bidirectional reflectance of multilayer emissive structures used in electronic display devices. I estimate the complete BRDF using a one-dimensional angular distribution function of the luminance. I apply the method to model typical high-performance cathode-ray tube and FPD structures. I find that, for the BRDF signatures of cathode-ray tubes characterized by a specular and a quasi-Lambertian components, the estimated values for the specular and diffuse reflection coefficients agree well with low-resolution experimental measurements conducted with a rotation arm and a collimated probe. I show that emissive FPDs with thin-film organic layers on reflective substrates can exhibit a predominant specular peak broadened by short-range light scattering.

Data Display↗
PubMed2004

Characterizing the "gold standard" image for laparoscopic surgery.

BACKGROUND: The term "gold standard" is often used to describe preferred display devices, frequently without substantiating evidence. A meaningful and objective measure of display quality for endoscopic surgery is required. METHODS: Typical colors from five tissue types were arranged in a striped pattern and displayed on four devices: a medical-grade cathode ray tube monitor, a liquid crystal display, a digital light projection display, and an obsolete cathode ray tube (CRT) monitor. The breadth and color contrast of the stripes were adjusted until the patterns became indiscernible to 12 subjects. The data provide a discernibility threshold. RESULTS: The liquid crystal display (LCD) monitor provided the best image. The medical grade and obsolete CRTs were second and third, respectively, and the projection display provided the most inferior image. CONCLUSIONS: A meaningful and relevant measurement of image display quality for laparoscopic surgery based on the discernibility threshold is provided. Of the devices tested, the LCD is the best in terms of image, although the CRT may be preferred at off-axis viewing angles. The projection system, however, offers compensatory ergonomic advantages.

Benchmarking↗
PubMed1978

A novel rapid scanning microspectrophotometer and its use in measuring rhodopsin photoproduct pathways and kinetics in frog retinas.

A novel rapid scanning microspectrophotometer is described which utilizes a cathode ray tube as a measuring light source. Spectral scanning is accomplished electronically with a sampling time of 600 mus for each waveband. The cathode ray tube emission is chopped electronically into two separate beams, 180 degrees out of phase, resulting in a dual-beam configuration. A lock-in amplifier functions as a coherent detector to recover separately the signals from the two beams. The instrument generates separate voltage outputs, one proportional to the transmittance of a single sample and the other to the difference between two samples. A computer calculates both absorption and difference spectra directly from voltage measurements. A demonstration of the instrument's use to study kinetics of visual pigment photoproducts is presented. Two models of photoproduct sequence and kinetics were examined to determine which better represents the experimental data. The experiments show that environmental factors, such as pH, metabolic and respiratory state, interact in complex ways to determine the pathways and kinetics of photoproducts of rhodopsin in intact vertebrate eyes.

Animals↗
PubMed1977

Computerized hematology: operation of a high-volume hematology laboratory.

Operation of automated hematology testing, on-line to a laboratory-dedicated computer, is described. The computer stores, retrieves and monitors the results of two Model S Sr. Coulter Counters, three Technicon platelet counters, one Electra 600-D, and six leukocyte differential consoles, which are interphased to the computer. All other hematology tests are batch-entered via the keyboard of cathode-ray tubes. The computer generates specimen labels, worksheets, and lists of incomplete tests, monitors all on-line instruments, and performs all the calculations used in the procedures of quality control. Results are available instantaneously on cathod-ray tubes strategically located in patient-related areas throughout the institution. These can be obtained as all of the results for a given day or as cumulative summaries or histogram-type plots of results for a given day.

Autoanalysis↗
PubMed2006

Economic analysis of electronic waste recycling: modeling the cost and revenue of a materials recovery facility in California.

The objectives of this study are to identify the various techniques used for treating electronic waste (e-waste) at material recovery facilities (MRFs) in the state of California and to investigate the costs and revenue drivers for these techniques. The economics of a representative e-waste MRF are evaluated by using technical cost modeling (TCM). MRFs are a critical element in the infrastructure being developed within the e-waste recycling industry. At an MRF, collected e-waste can become marketable output products including resalable systems/components and recyclable materials such as plastics, metals, and glass. TCM has two main constituents, inputs and outputs. Inputs are process-related and economic variables, which are directly specified in each model. Inputs can be divided into two parts: inputs for cost estimation and for revenue estimation. Outputs are the results of modeling and consist of costs and revenues, distributed by unit operation, cost element, and revenue source. The results of the present analysis indicate that the largest cost driver for the operation of the defined California e-waste MRF is the materials cost (37% of total cost), which includes the cost to outsource the recycling of the cathode ray tubes (CRTs) (dollar 0.33/kg); the second largest cost driver is labor cost (28% of total cost without accounting for overhead). The other cost drivers are transportation, building, and equipment costs. The most costly unit operation is cathode ray tube glass recycling, and the next are sorting, collecting, and dismantling. The largest revenue source is the fee charged to the customer; metal recovery is the second largest revenue source.

California↗
PubMed2004

An overview of recycling and treatment of scrap computers.

In order to recover valuable materials and to minimize the adverse effects of hazardous materials contained in scrap computers, a dismantling practice is commonly adopted to treat scrap computers. By using the dismantling process, both useful and hazardous materials can be manually separated and retrieved. On the basis of the properties of the retrieved materials, they can be sent to appropriate facilities for further recycling or treatment. Among the retrieved materials, the treatment of hazardous materials from cathode ray tubes (CRT) and printed circuit boards with integrated circuits have drawn considerable attention, thus implying that the proper treatment of such materials can greatly assure the successful recycling of scrap computers. For this reason, this study reviews the available technologies which can be applied to treat and recycle cathode ray tube components and printed circuit boards with integrated circuits. Actual recycling data from a scrap computer recycling plant located in Taiwan are also introduced. The data show that this recycling plant can recover 94.75 wt. % and 45.99 wt. % of useful materials from the main machines (i.e., CPU, power supplier, fan, IC boards, DVD drive, CD drive, hard disk, soft disk, shell casing, etc.) and monitors of scrap computers, respectively.

Computers↗
PubMed2003

Angular dependence of the luminance and contrast in medical monochrome liquid crystal displays.

Active-matrix liquid crystal displays (AMLCDs) are light-modulating devices that generate images by differentially transmitting a nearly uniform luminous field provided by a backlight. While emissive displays exhibit a quasi-Lambertian emission with almost constant contrast at off-normal viewing, the anisotropy of the electro-optic effect that controls light transmission in AMLCDs causes a pixel luminance that varies, sometimes strongly, with viewing angle. These variations are not identical for all gray levels and can eventually cause grayscale inversions. In this paper, we measured the luminance emission of a monochrome medical AMLCD, a medical cathode-ray tube monitor, and a color desktop AMLCD, using a collimated photopic probe positioned on a manual rotation arm, and a research radiometer with automatic readout. The probe measures luminance with a small acceptance angle and provides optical shielding from emissions at other viewing directions that contaminate the readings. We obtained luminance response curves versus angle in the vertical, horizontal and at 45 degrees diagonal directions. The display systems were calibrated to reflect the DICOM Part 3.14 standard grayscale display function (GDF) when measured using the manufacturer's probe and software tools. We analyzed the measurements at different viewing directions with respect to their departure from the GDF by computing the normalized contrast (deltaL/L) as a function of the DICOM just-noticeable difference index. Although cathode-ray tubes are known to be quasi-Lambertian emitters, the luminance at normal viewing is higher than the luminance observed at large angles. This decrease in luminance is however proportionally similar for all gray levels, resulting in a relatively flat contrast response for all angles. In addition to being more pronounced, the angular variation in AMLCDs does not follow the same profile at different intensities with the subsequent variation in the achieved display contrast. The changes due to off-normal viewing are substantial at large angles in the horizontal and vertical directions, and much worse in the diagonal viewing directions.

Anisotropy↗
PubMed1992

Practices and attitudes about cathode-ray tube-based and film-based image interpretation.

A questionnaire was mailed to 708 practicing radiologists and 348 members of the Society for Computer applications in Radiology (SCAR) in order to evaluate current practices and attitudes regarding the perceived advantages or disadvantages of film- and CRT-based image interpretation. A total of 27% of the 1,056 questionnaires (137 practicing radiologists; 145 SCAR members were returned. Ninety percent of practicing radiologists used film at least 75% of the time. Advantages of film-based reading listed by more than 75% of the respondents included: film reading is faster, and facilitates viewing multiple images. Advantages of CRT-based reading included: access to the entire dynamic range and potential imaging processing. Desirable attributes of existing displays included: adjustable grey scale, magnification, ability to view multiple images, allow quick review, and viewing by several individuals. Valued potential advances included: multiple higher resolution monitors, image processing and multimodality display. Practicing radiologists and computer applications society members had similar attitudes. Film-based reading is still nearly universal, but radiologists are interested in CRT-based reading if such devices have the proper features and become more available.

Attitude of Health Personnel↗