Radiographic Quality – Unit 4

A comprehensive set of question-and-answer flashcards covering image quality, resolution, noise, geometric factors, magnification, shape distortion, focal spot blur, the anode heel effect, and motion, based on Unit 4 lecture notes.

In radiography, what term describes the visible sharpness of the image, including resolution and detail?

Image quality

What two words are commonly used as the opposite of radiographic detail?

Penumbra or blur

What happens to image sharpness when simulated resolution drops from 300 dpi to 10 dpi?

Sharpness decreases because fewer and larger pixels represent the image

What resolution type is the ability to distinguish two separate high-contrast objects such as bone and soft tissue?

Spatial resolution

What resolution type is the ability to differentiate anatomical structures of similar subject contrast?

Contrast resolution

An increase in contrast resolution produces what visible change on the image?

More shades of gray, improving differentiation of similar tissues

Name three common forms of noise that degrade image quality.

Film graininess, structure mottle, and quantum mottle

Which noise results from irregular clumping of silver-halide crystals in the film?

Film graininess

What kind of noise is caused by physical imperfections in intensifying screens?

Structure mottle

Define quantum mottle and state when it is most likely to occur.

Grainy appearance from an uneven x-ray photon flux, especially with short exposure times and fast screens

How does increasing screen/film speed affect noise and radiographic quality?

Noise increases and radiographic quality decreases

List the three primary geometric factors that influence recorded detail.

Magnification, shape distortion, and blur

What type of distortion is a misrepresentation of the true size of the object on a radiograph?

Magnification (size distortion)

Which three distances determine the amount of magnification?

SID (source-to-image distance), SOD (source-to-object distance), and OID (object-to-image distance)

Write the formula for magnification factor using SID and SOD.

MF = SID ⁄ SOD

How do you calculate percent magnification?

(Image size – Object size) ÷ Object size × 100 %

What is the effect of increasing SID on magnification, detail, and penumbra?

Magnification and penumbra decrease; detail increases

Increasing OID changes magnification and detail in what way?

Magnification and penumbra increase; detail decreases

What is another name for SID that uses the word “focus”?

Focus-to-film distance (FFD)

Name the two main types of shape distortion.

Elongation and foreshortening

Shape distortion occurs when which three elements are not properly aligned?

The x-ray tube, the object, and the image receptor

A change in tube or IR angulation typically produces which type of shape distortion?

Elongation

Inclination of the object itself produces which type of distortion?

Foreshortening

How is magnification intentionally increased in macroradiography?

By decreasing SID

What focal spot size is typical for magnification mammography or angiography?

Fractional or microfocus focal spots (0.3 mm or smaller)

How does increasing focal spot size influence focal spot blur and detail?

It increases blur (penumbra) and decreases detail

Does focal spot size affect magnification?

No, focal spot size does not affect magnification

Which device can be used to measure the effective focal spot dimensions?

A pinhole camera

What unit is used in resolution test patterns to express spatial resolution?

Line pairs per millimeter (lp/mm)

Which combination provides the best radiographic detail: focal spot, SID, and OID?

Small focal spot, long SID, short OID

Because of the anode heel effect, which side of the x-ray tube emits higher radiation intensity?

The cathode side

How does decreasing the anode angle affect the heel effect?

A smaller (steeper) angle makes the heel effect more pronounced

Give one clinical example where positioning the thinner anatomy toward the anode side improves exposure uniformity.

Thoracic spine with the head at the anode end (also accepted: chest, femur/hip, or foot)

What is considered the biggest enemy of radiographic quality?

Motion

Name two common methods used to minimize motion blur.

Clear patient instructions, immobilization devices, tape, breath holding, or short exposure times