Influence Of Exposure Factors On X-ray Film Flashcards
What does the altering of kv affect
- Quality
- Intensity
Effects of Quality
- Influences the ability of x-ray photons to penetrate matter
- Influences the radiation dose of the patient
- It influences radiographic contrast
- Influences differential attenuation
Effects of Intensity
- Increase in kv increases the intensity of beam emitted from the peak tube
Focal spot
Point source of electrons
Types of focal spot
- fine focus
- Broad focus
When is fine focus likely selected
- Is selected when geometric factors are likely to limit image quality
- When dealing with small body parts eg fingers
Broad focus
- permits higher tube loading and is used for examination of bigger body parts
Filtration
- absorbs low energy x-rays inside the tube
Types of filtration
- inherent filtration
- Added filtration
FFD
distance from the x-ray tube to the image receptor
Intensity
An expression of rate of flow of radiation energy per unit area of cross section of the beam.
Relationship between intensity and FFD
- an inverse relationship exists, for instance, a doubled ffd will result in decrease in intensity by 1/4
Importance of collimation
- it reduces the amount of scattered radiation
- It reduces the area covered by the primary beam
- It reduces the volume of patient tissue radiated
Sec radiation grid
Is a device that is placed on top of the image receptor to absorb scatter radiation while allowing the rest to pass through.
The speed of an intensifying screen
- is the measure of the luminance that results from a specified exposure to x-rays.
What does the speed of intensifying screen depend on
- they depend on quantum detection efficiency
- Conversion efficiency
What is intensification factor
A quantity that indicates the speeds of different screens
Manipulation of exposure factors depend on?
- Body decubitus of patients
- Pathology of patients
- Badly injured patients
- Pregnant women
