step wedge

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step wedge

A quality control device consisting of increasing thicknesses of absorber through which radiographs are taken to determine the amounts of radiation reaching the film.
See also: wedge
Medical Dictionary, © 2009 Farlex and Partners

step wedge

(step wej)
Triangular aluminum device placed over a radiographic film during exposure to determine the penetrating ability of an x-ray beam.
Synonym(s): penetrometer.
Medical Dictionary for the Dental Professions © Farlex 2012
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Caption: Figure 5: Comparison of Gray Values for Thinner Aluminum Step Wedges. D, V, and M indicate the Digora, VistaScan, and Megadixel detectors' values.
Caption: Figure 6: Comparison of Gray Values for Thicker Aluminum Step Wedges. D, V, and M indicate the Digora, VistaScan, and Megadixel detectors' values.
Contrast for the thinner phantom (only the aluminum step wedge) was evaluated according to the contrast-to-noise ratio (CNR), which is defined by the following equation:
The phantom used in the study was an aluminum step wedge and a plate.
Concerning the radiopacity of materials, the International Organization for Standardization has stated that radiopacity is evaluated using the aluminum step wedge technique with a range of 0.5-5.0 mm thickness at 0.5 mm increments at an accuracy of >98% purity and 0.05 mm variation in thickness [17].
(a) Aluminum step wedge with 0.5, 1.0, 1.5, 2.0, 2.5, and 3 mm thickness.
Caption: Figure 7: Comparison of the Contrast-to-Noise Ratio (CNR) for the Thinner Aluminum Step Wedge. (a) Exposure condition with only the aluminum step wedge.
Numerical Evaluation of Image Contrast for Thicker and Thinner Objects among Current Intraoral Digital Imaging Systems

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