Image quality grading of dental radiographs

A two-point grading scale is now recommended

Grading the quality of dental X-ray images is an essential step in radiographic interpretation. It involves assessing the technical aspects of the image, such as image clarity, contrast, and detail, to determine its diagnostic value. The grading of dental X-ray image quality helps ensure accurate diagnosis and treatment planning. Here are some key factors considered when grading dental X-ray image quality…

Image Clarity/Sharpness: This refers to the overall sharpness and definition of structures in the X-ray image. A clear and sharp image allows for better visualization of anatomical details and helps identify any abnormalities. Factors that can affect image clarity include the X-ray exposure settings, positioning of the patient and X-ray film/sensor.

Contrast: Contrast refers to the range of gray shades in the X-ray image, which helps differentiate between different structures and tissues. A good contrast provides better visibility of dental structures and pathology. Factors that influence contrast include the X-ray exposure settings and equipment performance, film/sensor type, and image processing techniques.

Density: The density of an X-ray image refers to the overall darkness or lightness of the image. It is important to achieve an optimal density that allows for clear visualization of structures without excessive overexposure or underexposure. Overexposed images appear too dark, while underexposed images appear too light. Proper X-ray exposures settings and film processing (or image processing for digital imaging) are critical in obtaining the desired density.

Image Artifacts: Image artifacts are unwanted irregularities or distortions in the X-ray image that can affect its diagnostic value. Examples include film/sensor artifacts, processing artifacts (in the case of film-based radiography), foreign objects, and patient movement during exposure. The presence of artifacts can hinder the interpretation of the image and may require repeat exposures.

Anatomical Coverage: Anatomical coverage refers to whether the entire area of interest is visible in the X-ray image. Adequate anatomical coverage ensures that all relevant structures are included and can be properly evaluated.

Positioning: Proper positioning of the patient and X-ray film/sensor is crucial to obtain high-quality images. Incorrect positioning can result in distorted or incomplete images that may not provide the necessary diagnostic information.

Grading the quality of dental X-ray images helps ensure that the images meet the necessary standards for accurate diagnosis and treatment planning. In cases where image quality is suboptimal, efforts should be made to identify and address the factors affecting image quality to obtain improved radiographs.

Previously, a three-point grading scale (Excellent, diagnostically acceptable, diagnostically un-acceptable) was recommended by “Guidance Notes for Dental Practitioners on the Safe Use of X-ray Equipment”.  This document was published in 2001 when wet film processing was prevalent, since then with the advent of digital imaging the processing of images has become simpler and so has the recommended grading scale!  The 2020 2^nd edition of the same recommends a three-point scale: either “diagnostically acceptable – A” or “diagnostically not acceptable – N”, with a target of at least 95% of radiographs for digital imaging (90% for film imaging) being diagnostically acceptable.