Exam 1- Radiographic Density & Contrast

What is radiographic dentisty?

How light or dark the image appears

What is radiopacity?

the ability to stop the passage of x-rays

What is radiopaque?

Shows white on the film. Ex: enamel, bone, metal

What is Radiolucency?

Characteristic of materials that allow x-rays to penetrate

What is Radiolucent?

black or dark areas (ex. pulp, sinus)

What is an incident X-ray?

X-rays that strike the object

What is X-ray absorption / attenuation / blockage?

X-rays stopped or reduced by the object

What is transmitted x-ray?

X-rays that pass through the object and reach the receptor

What is a light blocking substance?

Radiopaque areas block viewing light → appear light

What is an incident viewing light?

Light shining from the view box or monitor

What is light absorption/attenuation?

Dark areas absorb light

What is transmitted light?

Light passing through radiolucent areas

What is reflected light?

light that bounces off an object

What are the radio density values mean? (1-3)

1 = very light

Higher numbers = darker image

What is radiographic contrast?

Difference between light and dark areas

What is high contrast?

Few shades of gray

Mostly black & white

Good for detecting caries

What is low contrast?

Many shades of gray

Better detail

Good for evaluating bone & pathology

What is a short contrast scale?

High contrast

Few grays

What is a long contrast scale?

Low contrast

Many grays

What factors effect the contrast?

Subject Contrast, Differential Absorption, Chemical Composition, Object Thickness, Object Density, Beam Energy (kVp), Scatter Radiation

What is subject contrast?

Differences within the patient's tissues

What is differential absorption?

Different tissues absorb X-rays at different rates

What is chemical compositon?

High atomic number → more radiopaque

What is object thickness?

Thicker objects absorb more X-rays

What is object density?

Denser objects appear lighter

What is beam energy in reference to kVp?

High kVp → low contrast (many grays)

Low kVp → high contrast (black & white)

What is scatter radiation?

Increases fog

Reduces contrast