film

Construction of X-ray Film and Screen

X-ray Film Overview

  • The X-ray film records images exposed to X-rays, functioning similarly to photographic film.

  • Unlike photographic film, it has a light-sensitive emulsion coated on both sides to work with intensifying screens.

Components of X-ray Film

  1. Film Base

    • The base supports the emulsion, needs to be flexible yet strong, withstand geometric distortion, and provide a transparent background.

    • Historically, glass plates, cellulose nitrate, and cellulose triacetate were used before polyester became the standard in the 1960s.

  2. Film Emulsion

    • Composed of gelatin and silver halide crystals, aiding in dispersion of silver halide and penetration of developing solutions.

    • Silver-iodo-bromide grains are the light-sensitive components, primarily consisting of silver bromide.

  3. Adhesive Layer

    • A clear gelatin layer adheres the emulsion to the base as they typically do not adhere naturally.

  4. Protective Layer

    • A thin outer layer (usually gelatin) protects the emulsion from scratches and damage.

Types of X-ray Films

Based on Photosensitive Emulsion Layers

  • Single Coated Films:

    • Emulsion on one side, used with specific single intensifying screens; offers higher image resolution.

  • Double Coated Films:

    • Emulsion on both sides and require less exposure time; generally used for routine purposes.

Based on Use with Intensifying Screens

  1. Screen Films:

    • Require less exposure due to sensitivity to light from screens; commonly used in diagnostic radiography.

  2. Non-Screen Films:

    • Used without screens, requiring more exposure; suitable for detailed imaging of fine tissue changes.

Based on Types of Light Sensitive Emulsion Coating

  1. Blue Light Sensitive Films:

    • Matches with blue light emitting intensifying screens, traditionally used with certain compositions.

  2. Green Light Sensitive Films:

    • Developed for use with screens emitting green light, incorporating specific dyes for sensitivity.

  3. "High Lite" Films:

    • Not sensitive to room light, allowing processing in a yellow-lit room.

Based on Film Speed

  • Film Speed: Refers to the sensitivity of the film to radiation, affecting exposure requirements and image quality.

    • Classified into Standard, Fast, and Ultrafast films, with faster films resulting in grainier images and narrow latitude.

Handling and Storage Care of X-ray Films

  1. Store films in cool (10-20°C) and low humidity (40-60%) environments.

  2. Keep film boxes vertically without pressure and away from heat or water sources.

  3. Load and unload films in a clean, dry environment under safe light.

  4. Handle films carefully; avoid splashing processing solutions.

  5. Discard films post-expiration.

  6. Exposed films should be placed in a dark room immediately to prevent further exposure.

  7. Wet processed films should be dried upright and not touched to avoid marks.