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Spatial Resolution and Angular Alignment Tolerance in Radiometric Analysis of Alveolar Bone Change
Author(s) -
Shrout Michael K.,
Weaver John,
Potter Brad J.,
Hildebolt Charles F.
Publication year - 1996
Publication title -
journal of periodontology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.036
H-Index - 156
eISSN - 1943-3670
pISSN - 0022-3492
DOI - 10.1902/jop.1996.67.1.41
Subject(s) - image resolution , pixel , radiography , resolution (logic) , histogram , optics , dental alveolus , materials science , nuclear medicine , physics , medicine , dentistry , artificial intelligence , computer science , image (mathematics) , radiology
T his pilot study was undertaken to determine the effect of x‐ray beam alignment and spatial resolution on quantification of alveolar bone using radiometric techniques. Six (6) dry mandibles were radiographed at 70 kVp, 10 mA, 0.6 seconds using D‐speed film, with a bone chip (2.64, 4.10, or 6.07 mg) present or absent at 7 x‐ray beam alignments (0°, 2° horizontal, 2° vertical, 4° horizontal, 4° vertical, 6° horizontal, 6° vertical). This resulted in 28 radiographs per mandible. Radiographs were digitized using 50‐ and 200‐μm pixel spatial resolution. Image gray levels were standardized using a simple look‐up table shift. Regions of interest (ROIs) were positioned on the alveolar bone where the bone chips had been placed. Cumulative percent histograms (CPH) were calculated for those ROIs. Regression analysis was used to evaluate the relationships between CPH changes and bone chip size as x‐ray beam angulation and spatial resolution was varied. The resulting R 2 values for angulation ranges of 0° to 1.4°, 1.5° to 2.4°, and 2.5° to 5.5° were: 0.983, 0.941, 0.891 for 50‐μm pixel images and 0.869, 0.909, and 0.774 for 200‐μm pixel images. We conclude that 50‐μm pixel spatial resolution is apparently superior to 200‐μm pixel images if radiometric data is to be evaluated. With 50‐μm pixel spatial resolution, alignment variations up to 5° may be acceptable in clinical studies, depending on the magnitude of bone change that is to be detected. J Periodontol 1996;67:41–45 .