Physics of Radiography Flashcards
Properties of X-rays
- Invisible
- Painless
- Latent effect
- Cumulative effect
Somatic Effect
-Minor to severe skin burns
-Cataracts in the eye
-Servere internal organ and blood damage
Carcinogenic Effect
Changes in the tissues can be maligant and develop into diseases
Genetic Effects
-Damage genetic material in reproductive organs, causing genetic mutation
Where are x-rays produced?
Tube head
Anode
Positive, made of tungsetn
Cathode
Negative, made from tungsten
What if the kV is too high?
The x-ray will appear very dark, with a loss of contrastr
Factors affecting kV include;
- Species
-Weight - Tissue density
- Tissue atomic number
What does milliamperage (mA) refer to?
Number of electrons produced at cathode
Greater mA
The blacker the film (overexposed)
Lower mA
The lighter the film (underexposed)
Factors effecting mA
- Tissue
- Thickness
- Density
What will happen if the patient is exposed to primary beam for longer?
More photons will be released from the x-ray, thus more photon-tissue interacrtions there will be.
What os the Film Focal Distance (FFD)?
Distance between focal spot and surface of the xray film
Absorption of x-ray- Bones
SG- High
Atomic Number- High
Colour- White
Absorption of X-rays- Water/muscle
SG- Medium/high
Atomic number- High
Colour-Grey
Absorption of X-rays- Fat
SG- Low/medium
Atomic Number- Low
Colour- Grey
Absorption of X-rays- Air
SG- Low
Atomic Number- lOW
coLOUR- Black
How to reduce scatter radiation?
- Grids
- Collimation
- Reduce tissue thickness
- Reduce kV
