Radiography Flashcards
How are you radiographic images obtained?
All about absorption of radiation by different radiographic tissues
What are the pros of using radiography for imaging?
Excellent for bone and gas
Okay for soft tissues
Good for large scale/ gross structure
What are the cons of using radiography
Radiation risk
What are radiolucent substructures?
Tissues are radiolucent and most waves pass all the way through
Low density things such as gases
Appear black on radiograph
What are radiopaque structures?
Most of the x rays are absorbed
Very dense tissue such as bone or metal
Appears white on radiograph
Why are some things on the radiograph black
X rays have been penetrated through the body and not been absorbed
Why are some things white on an radiograph
X rays have been absorbed by the body
What are X rays
For, of electromagnetic radiation, transverse waves
Short wavelength, so high frequency
Why are X rays dangerous
Due to high energy they can cause ionisation which can damage tissues
How can you make using radiography safer?
ALARP (As low as reasonably practicable):
Dose
Personnel
Times
Big distance
Use shielding
Don’t hold animal if possible
Use vertical beam if possible
How are x rays produced
Interaction of electrons with an atom
Cathode generates electrons, and then hit and interacts with the anode
What is the quality of the beam
Penetrating power
What is the intensity of the beam
Amount of radiation
What does increasing kV do
Increase electron acceleration
More x rays are produced
X rays have more energy, so increased penetrating power
What does changing current (mA do)
Increases tube current, so number of electrons, so greater number of x rays produced
Energy of x ray is unchanged
How does computed radiography work?
Phosphor plate held in cassette
When x rays strike plate, electrons are energised to form an invisible latent image (trapped energy)
Cassette is placed into reader and plate removed
Plate scanned by laser and trapped energy released as visible light
How does direct digital radiography work?
X rays stimulate sensor panel that sends electronic signals directly to computer
Image can be manipulated and stored as before
What is the mneumonic to remember when using radiography
Pink (position)
Camels (centring)
Collect (collimation)
Extra (exposure)
Large (labelling)
Apples (artefacts_
What is important when positioning for a radiograph?
Position part of interest as close to image- receptor as possible
Part of interest should be parallel to image receptor
What is centring when using radiography?
Centre the primary beam over the area of interest
How should you collimate a beam
To minimum size necessary
How can you limit scattered radiation?
Good collimation
Low kV
