RTFILM Prelims

Radiographic Dark Room

• Light-tight area for safe handling and processing of radiographic films
• Prevents film fog from light and scattered radiation

Darkroom Concrete Thickness

At least 6 inches to protect film from scattered radiation

Safelight

Special illumination that allows visibility without fogging the film

Film Fog

Unwanted film darkening caused by accidental light or radiation exposure

Film Color (Exposed)

Purple before processing

Film Color (Developed)

Black after processing

Intensifying Screen Function

Converts x-ray photons into visible light

Darkroom Location Requirements

• Near imaging room, away from heat, moisture, and primary beam
• Must be completely light-proof

Viewing Room Adjacency

Darkroom should adjoin the viewing area

Pass Box/Cassette Hatch

• Light-tight and x-ray-proof transfer box
• Only one door can open at a time

Minimum Darkroom Size

• Floor area: 10 m²
• Ceiling height: 2.7–3.3 m

Darkroom Shielding

6-inch solid concrete ≈ 1.62 mm lead equivalence

Primary Beam Safety

X-ray beam must never be directed toward darkroom walls

Darkroom Floor Requirements

• Non-porous, non-slip, chemical-resistant
• Light-colored for better safelight visibility (White or Cream)

Acceptable Floor Materials

Asphalt, porcelain, clay, or plastic tiles (dry rooms)

Wall Protection

Chemical-resistant up to 1.3 m near wet areas

Wall & Ceiling Color

Light, glossy colors to maximize light reflection

Ceiling Requirements

Minimum height 2.7 m, non-flaking paint

Ventilation Purpose

Maintains film quality and staff comfort

Environmental Conditions

• Temperature: 18–20°C

• Humidity: 40–60%

Air Exchange Requirement

5–10 air changes per hour

Single Door Entrance

Usual used door, Lockable from inside with emergency release

Double Door Entrance

Prevents outside light entry

Labyrinth (Maze) Entrance

• Reduces light intensity via multiple reflections

• Should have Height: 2 m, Length: ≥3 m, Width: ≤700 mm

• Easy access, allows fresh air, safe for solo workers

Revolving Door Entrance

Light-proof but slower exit

White Lighting

Used for cleaning, inspection, and maintenance

Safelight

Colored light that minimizes film fogging

Direct Safelight

• Illuminates work surface directly
• Minimum distance: 1.2 m

Indirect Safelight

Light reflected from ceiling for general illumination

Safelight Filter

Gelatin filter used with 25 W bulb

Filter Maintenance

Heat and moisture degrade filters; clean regularly

Safelight Testing Indications

New darkroom, new safelight, suspected fogging

Safelight Test Result

Darker exposed half = unsafe lighting

Automatic Processing Darkroom Equipment

• Automatic processor

• loading bench

• cassette racks

Manual Processing Darkroom Equipment

• Tanks

• sink

• hangers

• dryer

• chemical storage

Loading Bench Dimensions

Length: 2.5 m, Width: 600 mm, Height: 900 mm

Bench Surface

Teak with linoleum; anti-static and easy to clean

Film Hopper

• Stores unexposed films for immediate use
• Must not be opened under white light

Film Hangers

Used to suspend films during manual processing

Types of Hangers

• Channel

• tension

• hanger bars and clips

Darkroom Sink

• Located near processing unit
• Supplies hot and cold water

Film Drier

Uses warm air circulation to dry processed films

Well-Planned Darkroom

• Separation of wet and dry areas
• Organized workflow and clear traffic lanes

Darkroom Electrical Safety

Proper grounding, no trailing cables, pull-cord switches

Radiography

Use of x-rays to produce images on photosensitive material

Radiograph

Recorded x-ray image showing anatomy as light and dark areas

Good Radiograph

Indictors:

• Proper exposure

• positioning

• contrast

• no motion

Radiographer

Professional trained to produce diagnostic radiographs

Image Receptor

Types of Image Receptors

• Film

• solid-state

• image intensifier

Radiographic Film

Permanent image recorder using silver halide crystals

Film Thickness

150 – 300 μm

Emulsion Thickness

3 - 5 μm

Film Base

Provides flexible support

Adhesive Layer

Binds emulsion to base

Emulsion

• Active layer containing silver halide crystals

• Gelatin + silver halide crystals

• 3 - 5 μm

Protective Coating (Overcoat)

Protects emulsion from damage

Silver Halide Function

Records the latent image

Silver Halide Composition

98% AgBr, 2% AgI

Common Crystal Shape

Tabular (flat)

Radiographic Film Base

Polyester plastic with blue tint

Base Density

0.14 OD

Intensifying Screen

• Converts x-ray energy into light to expose film

• Reduce patient dose (+)

• BUT Reduced spatial resolution (-)

PARTS OF THE INTENSIFYING SCREEN

• Screen Base – Structural support

• Reflective Layer – Redirects light to film

• Phosphor Layer – Emits visible light

• Protective Coating – Prevents scratches and static

Common Phosphors

• Calcium tungstate

• Rare earth elements

Spectral Matching

Film sensitivity must match screen light color

Film-Screen Contact

Must be uniform for image sharpness

Wire Mesh Test

Detects poor contact via blurring

Beam Filtration

• Removes low-energy x-rays

• Improves beam quality and patient safety

Best Beam Restrictor

Collimator

Beam Restriction

Limits field size to reduce scatter

Collimator

• Adjustable shutters controlling beam size

• Uses light mirror to indicate field

Protective Apparel

• Lead gowns

• gloves

• goggles for radiation protection