ENDTERM Flashcards
What does radiographic quality refer to?
The fidelity with which anatomic structure being examined is imaged on the radiograph.
What are the important characteristics of radiographic quality?
- Spatial resolution
- Contrast resolution
- Noise
- Artifacts
How does spatial resolution improve?
As screen blur decreases, motion blur decreases, and geometric blur decreases.
What is contrast resolution?
The ability to distinguish anatomic structures of similar subject contrast.
What does noise refer to in radiographic imaging?
Random fluctuation in the optical density of the image.
What are the four components of noise?
- Film graininess
- Structure mottle
- Quantum mottle
- Scatter radiation
What is the definition of quantum mottle?
The random nature by which x-rays interact with the image receptor.
What is relative speed in radiography?
A measure of screen speed connected with resolution and noise.
What does the characteristic curve (H&D curve) describe?
The relationship between optical density (OD) and radiation exposure.
What is Dmax?
The maximum density the film is capable of recording.
What is optical density?
The amount of overall blackness produced on the image after processing.
What happens if a radiograph is too light?
There is insufficient density to visualize the structures of the anatomic part.
What is the effect of increasing kilovoltage-peak (kVp) on radiographic density?
It increases the penetration ability of the x-ray beam, resulting in increased density.
What is the 15 percent kVp rule?
A 15 percent increase in kilovoltage causes a doubling of exposure to the film.
What is the effect of milliamperage-seconds (mAs) on radiographic density?
It has a direct proportional relationship with the quantity of x-rays produced.
What is the effect of source-to-image receptor distance (SID) on radiographic density?
The intensity of radiation varies at different distances; increased SID decreases radiographic density.
What is the anode heel effect?
A decrease in intensity at the anode end of the primary beam that affects uniformity of densities produced.
How does the thickness of anatomic parts affect radiographic density?
- Thicker parts decrease radiographic density
- Thinner parts increase radiographic density
What is the relationship between beam restriction and radiographic density?
Restricting the beam reduces the total number of photons available, decreasing overall density.
What factors influence radiographic density?
- Focal spot
- mAs
- kVp
- Anode heel effect
- Distance
- Filtration
- Beam restriction
- Anatomical part
- Grids
- Film/screen system
- Film processing
What does radiographic contrast refer to?
The degree of difference between adjacent densities.
What are the terms used to describe the scale of contrast?
- Long-scale
- Short-scale
What is the relationship between kVp and scale of contrast?
- High kVp produces low contrast (long scale)
- Low kVp produces high contrast (short scale)
What increases radiographic density during film processing?
Increasing developer solution temperature, immersion time, or replenishment rates.
What is the effect of excessive or insufficient tube filtration on radiographic density?
It may affect the radiographic density.
What relationship does kVp have with the scale of contrast?
kVp affects the scale of contrast in radiographic images.
What does high kVp produce in terms of contrast?
Low contrast
High kVp results in less differentiation between shades in the image.
What does low kVp produce in terms of contrast?
High contrast
Low kVp results in greater differentiation between shades in the image.
What is a long scale of contrast associated with?
Low contrast
A long scale indicates a gradual transition between different shades.
What is a short scale of contrast associated with?
High contrast
A short scale indicates a sharp transition between different shades.
What does radiographic contrast consist of?
Total amount of contrast from both subject contrast and film contrast.
What is film contrast?
Difference in optical density (OD) between different areas on the film.
What does subject contrast describe?
Different amounts of exit radiation through different parts of the body.
What is the primary controlling factor for radiographic contrast?
kVp
Ability to image two separate objects and visually distinguish one from the other
Resolution
Ability to image small objects that have high contrast such as bone, soft tissue interference, breast calcification or calcified lung nodules
Spatial Resolution
ability to distinguish anatomic structures of similar subject contrast
Contrast Resolution
Degree of density difference between two areas on a radiograph
Contrast Resolution
unwanted on images
Artifacts
refers to the distribution in size and space of silver halide grains in the emulsion
Film Graininess
similar to film graininess
refers to the phosphor of the radiographic intensifying screen
Structure mottle
Principal contributor to radiographic noise in many radiographic imaging procedures
Quantum Mottle
What reduces quantum mottle?
High mAs, Low kVp, Slower Image Receptors
Interrelated characteristics of radiographic quality
Resolution, Noise, Speed
