Dental X-ray Image Characteristics

radiolucent

Radiographic Density & Contrast

• Dark/black areas on a radiograph (e.g., air spaces, caries).

radiopaque

Radiographic Density & Contrast

• Light/white areas on a radiograph (e.g., enamel, dentin, bone).

Milliamperage (mA), Kilovoltage (kVp), Exposure time

exposure factors of density

Thickness, density, film fog

subject factors of density

higher density (darker image)

Effect of kVp on Density

• higher kVp =

lower density (lighter image)

Effect of kVp on Density

• lower kVp =

film contrast

Contrast (Difference in degrees of blackness)

• Film quality and processing

subject. contrast

Contrast (Difference in degrees of blackness)

• Object thickness, density, and composition

short-scale contrast

Effect of kVp on Contrast

• Only black & white (low kVp)

long-scale contrast

Effect of kVp on Contrast

• Many shades of gray (high kVp)

penumbra

Sharpness (Detail, resolution, or definition)

• Unclear, blurred edges of an image.

focal spot size, film composition, movement

factors affecting sharpness

higher sharpness

factors affecting sharpness

• lower focal spot

higher sharpness

factors affecting sharpness

• lower crystal size

higher sharpness

factors affecting sharpness

• lower movement

target film distance

Magnification (Enlargement of image)

• xray source to film

object film distance

Magnification (Enlargement of image)

• tooth to film

less magnification

longer PID =

less magnification

closer placement =

parallel

Distortion (Change in shape or size)

• Object-Film Alignment: Must be —; misalignment causes distortion.

perpendicular

Distortion (Change in shape or size)

• X-ray Beam Angulation: Must be — to the tooth and film to maintain accuracy.