dose reduction mechanisms Flashcards
Goals for Oral and Maxillofacial
Radiology
- Reduce radiation exposure
- Maintain a high degree of diagnostic
efficiency
juggling act of oral radiology
●reduce a patient’s radiation exposure
●maintain a high degree of diagnostic efficiency
Dose Reduction Mechanisms
X-ray Tube Head
Patient Protection
Operator Safety
Et cetera
ALARA:
As Low As Reasonably Achievable
Guiding Principle ofRadiation Protection
Since the probability or severity of biological damage increases as the radiation dose increases, it is desirable to avoid receiving even the smallest dose of radiation unnecessarily.
ALADA:
As Low As Diagnostically Acceptable
Guiding Principle of Radiation Protection
* ALADA lowers exposure to patients
* ALADA lowers exposure of all office personnel
mandated dose reduction mechanisms of tube head
- Filtration
- Collimation
purpose of the filter
removal of low E (large wavelenght) photons
* Selectively removes a greater proportion of low keV x-ray photons
* Increases mean energy of the beam
based on? Al filtration needed?
Mandated Minimum Total Filtration
for X-ray Tubes
majority of machines in the 50-70/ 1.5mm range
tube head collumination
mandated on tube side
can be circular or rectangular
* Maximum 2.75” diameter
* (Rectangular preferred)
optional dose reduction mechanisms xray tube options
- Rectangular collimator
- High kV generator/ transformer
- Constant potential (DC) fully rectified
- Increased focal length
rectangular collimination
decreases beam size to size of receptor= decrease in dose
no compromise to diagmostic info if done correctly (alignment)
must learn to have precise placement of both source and receptor
area exposed and beam size
directly related
what can help with rectangular collimnator alignment
ring assemblies like in clinic (XDR?)
can depend on?
_________ dose is reflective
of the specific technique
effective dose is reflective of the specific technique
can depend on receptor and collination
higher kV and dose
will actually reduce the dose, may be due to increased filtration measures (distance and actual filter)
higher kV units are?
larger and heavier