Reducing radiation dose Flashcards
What are the principles of reducing radiation dose
Justification & Optimisation
How does justification impact radiation dose
Only taking x-ray if it is likely to affect patient’s dental management, there must be benefit to receiving this x-ray
How is radiation dose made ALARP
- Rectangular collimation
- Beam aiming device
- Long fsd
- Restrict irradiated areas where possible
- Film speed (at least E speed, F is faster)
- Quality assurance
- Image evaluation
What are deterministic effects
the severity of the effect is related to the amount of exposure and only occurs after a certain threshold is exceeded
What are stochastic effects
the risk of the effect is related to the amount of exposure
What xray has highest radiation dose
CBCT (highest)
Panoramic
Maxillary occlusal
PA/Bitewing (lowest)
What is the effect of radiation
Ionising radiation can disrupt structural organic molecules and cells of building elements of our bdoy and the DNA in the cell nucleus
What does the biological effect of radiation depend on
o type of radiation
o amound of radiation/dose
o time over which dose is received
o type of tissue irradiated
What is equivilant dose
o takes into account radio-biological effectiveness of different types of radiation
o equivalent dose = absorbed dose x radiation weighting factor
o radiation weighting factor for x-rays is 1
What is effective dose
o takes into account radiosensitivity of different types of tissues
o some body parts are more sensitive to radiation than others
o this allows for different investigations irradiating different parts of the body to be compared by converting all doses to an equivalent whole body dose
o uses a tissue weighting factor
Panoramic anatomy
