Radiographic latitude

Radiographic latitude describes the range of exposure or object-thickness variation that an imaging system can represent usefully under a defined technique. It helps explain why one exposure may show useful detail across some thickness changes but not others.

What it means in an examination

Latitude and contrast describe different aspects of an image. A system that can capture a broad exposure range still needs adequate contrast, resolution and signal quality for the inspection task. Avoid treating the ability to display a bright and a dark area as evidence that both areas meet the examination requirements.

Important distinctions

For digital radiography, distinguish captured detector information from display settings. Window and level adjustments change the presentation of recorded data; saturated or inadequately exposed regions may not contain usable information. The approved procedure and its image-quality checks determine whether the examination is acceptable.

Using the term correctly

When discussing a technique, specify the material, thickness range, geometry and imaging system. Keep the exposure and processing records needed to reproduce and review the image. Do not use a generic latitude value from a different system as an acceptance criterion.

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