This document discusses dental x-ray image characteristics including visual and geometric properties. Visual characteristics include density, contrast, while geometric characteristics are sharpness, magnification, and distortion. Density represents film darkening and is influenced by exposure factors and object thickness. Contrast is the difference in densities between regions and is influenced by subject contrast and kVp. Sharpness measures detail reproduction and is impacted by focal spot size and distances. Magnification increases with closer subject-film distance. Distortion alters shape and size from the film and teeth relationship or beam alignment. Proper interpretation involves localization, observation, general considerations and correlation of radiographic features.
1. Dental X-ray Image Characteristics Dr. Walid Samir Salem BDS, MS, MHPE lecturer, Oral Surgery Department Member, Dental education unit College of Dentistry, Qassim University
12. Exposure factors (mA, kVp, exposure time). An unnecessary increase in any of these factors results in an increase in film density. Object thickness: the larger the patient’s head, the more x-rays that are needed to produce an ideal film density Object density: determined by type of material (metal, tooth structure, composite, etc.) and by amount of material
13. FilmFog 0 Increased film density from causes other than exposure to the primary x-ray beam (scatter, improper safelighting, improper film storage, expired film) fog
14. 0 II) Contrast The difference in densities (blackness) between various regions on a radiograph
15. 0 High Contrast Short Scale Black and White (Few shades of gray) Best for caries detection
16. 0 Low Contrast Long Scale Many shades of gray Best for periapical or periodontal evaluation
18. Subject contrast 0 Results from varying object densities within patient, this is determined by: thickness, density & composition of the subject
19. 0 kVp Affects energy (penetrating ability) of x-rays. 50 60 70 80 90 100 40
20. Film contrast: 0 It refers to the characteristics of the film that influence the radiographic contrast, it is incorporated into film by manufacturer.
21. FilmFog 0 Film fog makes the whole film darker, making it harder to see the density differences (contrast) fog
22. I) Sharpness Measures how well the details (boundaries/edges) of an object are reproduced on a radiograph. The fuzzy unclear area that surround the image is termed penumbra.
23. Penumbra (pene=almost + umbra= shadow) Def.: Zone of unsharpnessalong the edge of images in a radiograph The larger the penumbra, the less sharp the image will be
30. 0 Film crystal size The faster film contain larger crystal size that produce less image sharpness, and vice versa. Unsharpness occur because the large crystals don’t produce object outline as well as smaller.
38. 0 Ideal Radiograph Image same size as object Image same shape as object Image has good detail Image has good density and contrast
39. 0 Mandibular molar periapical film comes closest to satisfying properties of an ideal radiograph (either paralleling or bisecting)
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41. Radiographic Interpretation basic Dr. Walid Samir Salem BDS, MS, MHPE lecturer, Oral Surgery Department Member, Dental education unit College of Dentistry, Qassim University
47. Interpretation Vs. Diagnosis: Interpretation refers to an explanation of what is viewed on a radiograph while diagnosis refers to the identification of disease by examination or analysis. In other words the interpretation is a step in the diagnosis.
48. Rules of radiographic interpretation The area to be examined must be completely shown at optimal angulations All the boundaries of the area of interest must be shown with normal structures around it. Knowing and familiarity with all normal anatomical landmarks as well as all various pathological conditions that may affect the area of interest. Optimum viewing condition.
55. Image Analysis: The first step in image analysis is to use a systemic approach to identify all the normal anatomy present in an image. Avoid limiting your attention to one particular region of the film.
56. Steps of interpretation Localization. Observation. General consideration. Interpretation. Correlation.
58. How to identify the position of the periapical film? Embossed dot identify right from left and the anatomical land mark to identify the jaw and the area.
62. Observation All shadows, other than the localized shadows of the normal landmarks must be observed. For example: shadows in crowns, cervical area, roots, restorations, size of root canals, periodontal membrane space, periapical area, alveolar crest, foreign bodies, integrity of bone …………
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64. Cervical burnout: usually appears as cervical RL and misinterpreted by caries; this occurs due to less density and more penetration of rays.
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66. Bone Changes in bone may include: 1- Changes in density. 2- Changes in the margin 3- Changes inside the lesion. 4- Effect on surrounding tissues. 5- Changes in structure
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If the viewing area is larger than the film, an opaque mask should be used to eliminate all light from around the periphery of the film.
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