QA/QC Tests

219 Topic 2

Dark Room

A lightproof space designed for developing x-ray films into visible diagnostic images using chemical solutions or an automatic processor.

Latensification

An increase in sensitivity, by as much as 2-8 times, in film that has already been exposed to light or ionizing radiation compared to unexposed film.

Film Sensitivities

Film can be affected by excess heat, humidity, static electricity, pressure, and chemical fumes.

OSHA Classification

The Occupational Safety and Health Administration classifies a darkroom as a laboratory.

Minimum Darkroom Guidelines

The space should be clean, well-ventilated, well-organized, a non-smoking zone, and static-free.

Ventilation Functions

Prevents the build-up of heat and humidity and removes excessive fumes from processing solutions that may sensitize film emulsions.

Ventilation Placement

A ventilator duct should be placed near the floor, in either the lower portion of the entrance door or the wall.

Humidity Range

The proper range is 30% to 60% of relative humidity.

Psychrometer

A device used to monitor humidity in the darkroom.

Static Electricity

Proper humidity minimizes the induction of static electricity.

Temperature Range

Should be maintained between 65° to 75°F (18° to 24°C).

Processing Fumes

Considered toxic, corrosive, and potentially carcinogenic.

OSHA PEL for Acetic Acid

25 mg/m³ (10 parts per million [ppm]).

OSHA PEL for Ammonium Thiosulfate

35 mg/m³ (as ammonia) (50 ppm).

OSHA PEL for Hydroquinone

2 mg/m³ (0.44 ppm).

OSHA PEL for Phenol

19 mg/m³ (5 ppm).

OSHA PEL for Sulfur Dioxide

13 mg/m³ (5 ppm).

OSHA PEL for Glutaraldehyde

0.7 mg/m³ (0.2 ppm).

OSHA PEL for Silver

0.01 mg/m³.

Darkroom Disease

A condition where radiographers or darkroom technicians have hypersensitivity to darkroom chemicals.

Darkroom Disease Symptoms

Hives, severe fatigue, and impairment of the immune system.

Indications of Proper Ventilation

Humidity and temperature are within range and chemical exposure is well below PEL.

Drainage Capacity

Drains must handle 2.5 times the maximum outflow of the processor when all drains are open.

Darkroom Walls

Should use enamel or epoxy paints in pastel and light colors with a matte finish and have shielding equivalent to adjacent radiation areas.

Storage Methodology

Uses a "first in, first out" methodology with separate areas for chemicals and films.

Film Storage Position

Films must be stored in an upright position.

Passbox

A film transfer system that prohibits white light from entering.

Static Reduction Methods

Grounding countertops/mats, proper film handling, wearing natural fibers like cotton, and regular screen cleaning with antistatic cleaner.

Darkroom Lighting Types

Consists of overhead lights and safelights.

Overhead Lighting

Standard white light necessary for cleaning, maintenance, and emergencies.

Overhead Light Standards

Standard fluorescent fixtures with 2-4 48-inch tubes per 8 square feet, interlocked with the film bin.

Safelight

A light source emitting wavelengths to which particular films are not sensitive, placed 3-4 feet from work areas.

Average-sized Darkroom Safelight

Fixture with a 7.5W or 15W bulb covered by a filter like Kodak Wratten 6B or Kodak Mor-Lite.

Large Darkroom Safelight

Sodium vapor lamp mounted at least 6 feet above counters for bright conditions.

Blue-Violet-Sensitive Film

Sensitive to blue, indigo, and violet; normally uses an amber-colored safelight.

Orthochromatic Film

Mainly sensitive to the green spectrum plus blue-violet; uses red or magenta dye and filters like Kodak GBX or Kodak 2.

Panchromatic Film

Sensitive to all visible colors; uses a dark green filter like Kodak Number 7.

Light and Leakage Testing

Includes safelight testing and darkroom light leakage testing.

Safelight Unsafe Conditions

Caused by cracks/pinholes in filters, wrong bulb wattage, or sodium vapor lamp doors open too far.

Safelight Testing Frequency

Done semiannually or more frequently if problems are discovered.

Filter Replacement Schedule

Annually if turned on 24/7 or every 2 years if on 12/7.

Penetrometer Procedure

Involves exposing a fresh film at a 40-inch SID with 70 kVp and 5 mAs to achieve an OD of approximately 1.

Maximum Acceptable Safelight Fog

Less than 0.05 Optical Density units for dual-emulsion films.

Sensitometer Procedure Limits

Maximum density difference should not exceed 0.05 OD for dual-emulsion or 0.02 OD for single-emulsion films.

Leakage Testing Procedure

Turn on outside lights, turn off darkroom lights, adapt for 5 minutes, and check for white light leaks.

Processor Area Check

Inspect countertops for objects, dampness, and sharp edges to prevent artifacts.

Film Storage Conditions

Temperature between 55-75°F (14-24°C) and humidity between 30-60%.

Chemical Storage Conditions

Well-ventilated area, temperature between 40-85°F (5-30°C), not exceeding 70°F for extended periods.

Intensifying Screen Development

Thomas Alva Edison developed IS in 1896; Michael Pupin first used the film/screen combination a year later.

Luminescence

Light emission from phosphor crystals energized by x-rays.

Fluorescence

Light emitted within 10⁻⁸ seconds after crystals are exposed.

Phosphorescence

Light emitted sometime after 10⁻⁸ seconds after crystals are exposed.

Intensifying Screen Speed

The amount of light emitted by the screen for a given amount of x-ray exposure.

Intensification Factor (IF)

Exposure without screen divided by exposure with screen.

Relative Speed

Most common designation method for screen speed, typically a multiple of 100.

New mAs Formula

(Old mAs × Old Relative Speed) / New Relative Speed.

Screen Speed Names

Range from Ultrahigh/Hi-plus (300) to Ultradetail (25).

Speed Uniformity Standard

Optical density readings should not vary by more than ±0.05.

Spectral Matching

Requirement that intensifying screen phosphors (blue or green) match the color sensitivity of the film