Biomedical subjects

A Attaelmanan

Publications and source records attributed to A Attaelmanan.

3 recordsLinked to original sources

PubMed2000

Image plate systems differ in physical performance.

OBJECTIVE: The purpose of this study was to compare 2 storage phosphor image plate systems, the Digora and the DenOptix, with respect to physical performance. STUDY DESIGN: The 2 systems were tested both with and without use of their default settings through physical and psychophysical measurements. A homogeneous 10-mm-thick aluminum block, a 10-mm-thick aluminum block with a pattern of holes varying in diameter and depth, and a resolving power target were used as test phantoms. The image plates were exposed at 50 kV and 8 mA with a focus-sensor distance of 30 cm and exposure times ranging from 10 to 3,200 ms. Measurements of large area transfer function, gray level variations, perceptibility, contrast resolution, exposure range, and modulation transfer function were performed. RESULTS: When the two systems were used at their default settings, the DenOptix had a better dose response, a higher contrast index, and a higher modulation transfer function (MTF) than the Digora; however, the DenOptix also had higher noise than the Digora at lower exposures. CONCLUSIONS: When image enhancement algorithms were applied with the Digora system, performance similar to that of the DenOptix could be obtained.

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PubMed2000

Subjective image quality of solid-state and photostimulable phosphor systems for digital intra-oral radiography.

OBJECTIVES: To compare subjectively the image quality of intra-oral radiographs from six digital systems. METHODS: Two generations of two different solid-state detectors; Visualix-1 and -2 (Gendex Dental Systems, Milan, Italy), Computed Dental Radiography (CDR) and CDR Active Pixel Sensor (APS) (Schick Technologies Inc., Long Island City, NY, USA), and two photostimulable phosphor (PSP) systems; Digora (Soredex, Orion Corporation, Helsinki, Finland) and DenOptix (Gendex Dental Systems, Milan, Italy) were compared. Tooth-containing specimens from different areas of dried mandibles were radiographed at exposures between 91-9400 microGy. Images were transferred to a personal computer, displayed in random order and evaluated in their original form and after applying a histogram equalisation algorithm. Eight observers graded subjective image quality using a 5-point scale. RESULTS: Both CDR systems scored highest for image quality but within the narrowest exposure range. The Visualix images received the lowest scores. The PSP systems produced acceptable image quality at both lower and higher exposures than the solid-state systems. Enhanced images were generally considered to be inferior to the original images, except for those produced by the four solid-state systems at very low exposures. CONCLUSIONS: (i) the PSP systems provided a clinically acceptable image quality over a wide exposure range; (ii) the CDR systems had the best image quality but over the narrowest exposure ranges; (iii) the Visualix systems had the lowest image quality; and (iv) histogram equalisation did not generally improve image quality.

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PubMed2000

Digitisation and display of intra-oral films.

AIM: To determine the optimal parameters for the digitisation and display of intra-oral radiographs. MATERIALS AND METHODS: Six intra-oral radiographs (EP size 2 dental film, Eastman Kodak Co., Rochester, NY, USA) were digitised using an Arcus II image scanner (Agfa-Gevaert N. V., Mortsel, Belgium). Each film was digitised at 8 bits, with and without a film mask, using three scanner resolutions (200, 400 and 600 p.p.i.), resulting in six versions of each radiograph. Seven experienced observers were asked to evaluate the quality of the resulting images as they were displayed on a Nokia 445Xi monitor (Nokia Display Products, Helsinki, Finland). Monitor settings were varied by changing the colour palette and screen resolution. RESULTS: Digital images of masked films had a statistically significant (t-test with alpha 2 tail < or = 0.05) higher quality than those scanned without a mask. The best image quality was obtained at a resolution of 400 p.p.i. Display options were optimum with 256 colours and a screen size of 1152 x 864 pixels. CONCLUSIONS: Better results were obtained when intra-oral radiographs were digitised with a mask at a resolution of 200 or 400 p.p.i. and displayed using 256 colours and the largest screen size possible. Further studies are needed to extend these results to other makes and models of scanner and monitor.

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