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.
